Cardiff School of Sport

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Daniel Ismail St20000585

SES

The effects of traditional strength and blood flow restriction training versus a

combination of both on measures of strength, hypertrophy and power in elite

athletes.

Dr Rhodri Lloyd

CARDIFF METROPOLITAN UNIVERSITY

PrifysgolFetropolitanCaerdydd

CARDIFF SCHOOL OF SPORT

DEGREE OF BACHELOR OF SCIENCE (HONOURS)

SPORT AND EXERCISE SCIENCE

2013-4

THE EFFECTS OF TRADITIONAL STRENGTH AND BLOOD

FLOW RESTRICTION TRAINING VERSUS A COMBINATION OF

BOTH ON MEASURES OF STRENGTH, HYPERTROPHY AND

POWER IN ELITE ATHLETES.

(SCRAM)

Daniel A Ismail

St20000585

THE EFFECTS OF TRADITIONAL STRENGTH AND BLOOD FLOW RESTRICTION

TRAINING VERSUS A COMBINATION OF BOTH ON MEASURES OF STRENGTH,

HYPERTROPHY AND POWER IN ELITE ATHLETES.

Cardiff Metropolitan University

PrifysgolFetropolitanCaerdydd

Certificate of student

By submitting this document, I certify that the whole of this work is the result of my

individual effort, that all quotations from books and journals have been acknowledged, and

that the word count given below is a true and accurate record of the words contained

(omitting contents pages, acknowledgements, indices, tables, figures, plates, reference list

and appendices).

Word count: 11.287

Name: Daniel

Date: Ismail

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The University owns the right to reprint all or part of this document

TABLE OF CONTENTS

CONTENT PAGE NUMBER

CHAPTER I: INTORDUCTION 22

CHAPTER II: LITERATURE REVIEW 25

2.1 Mechanisms of BFR

2.2 BFR and clinical populations 27

2.3 BFR and healthy untrained populations 28

2.4 BFR versus TST 30

2.5 BFR and athletic populations 31

CHAPTER III: METHODOLOGY 37

3.1 Experimental design 38

3.2 Participants 38

3.3 Height and body mass 39

3.4 Measurements of hypertrophy 39

3.5 Measurements of strength 39

3.6 Measurements of power 40

3.7 Training protocol 40

3.8 Blood flow restriction 41

3.9 Rating of Perceived Exertion (RPE)

and Rating of Perceived Sensation (RPS) 41

3.10 Statistical Analysis 42

CHAPTER IIII: RESULTS 43

4.1 Changes in thigh girth 44

4.2 Changes in 1RM strength 45

4.3 Changes in countermovement jump height 45

4.4 Training variable effect size in TST, BFR and

TST-BFR groups 46

4.5 RPE and RPS scores 46

CHAPTER V: DISCUSSION 47

5.1 Main findings 48

5.2 BFRT intervention 48

5.3 TST intervention 49

5.4 TST-BFR intervention 50

5.5 Comparison of training intervention 52

5.6 BFR effects on RPE and RPS 53

5.7 Practical implications 54

CHAPTER VI: CONCLUSION 57

6.1 Main finding of the study 58

6.2 Limitations of the study 58

6.3 Future directions for research 59

CHAPTER VII: REFERENCES 60

CHAPTER VIII: APPENDICES

A1. Ethics form A1

A2. BFR session plan A2

A3. A visual analogue to measure athletes A3

rate of perceived sensation

LIST OF TABLES

PAGE NUMBER

TABLE 1 44

Physical characteristics

TABLE 2 44

Pre- and post-test data of strength,

power and girth measures by training intervention

TABLE 3 46

Effect size on pre- to post-test training variables

LIST OF FIGURES

PAGE NUMBER

FIGURE 1 41

Visual analog of RPE and RPS

FIGURE 2 42

A schematic representation of the studies experimental design

i

ACKNOWLEDGEMENT

First of all I would like to thank my tutor and supervisor Dr Rhodri Lloyd for his help and

support. I have fully appreciated his knowledge and guidance throughout this entire

process which has been invaluable. Secondly, I would like to thank Dr Jeremy Loenneke

who inspired me to research the subject area. Furthermore, I would also like to thank the

athletes who took a lot of time out of their very important commonwealth training schedule

to participate in the study. Finally, I would like to thank Jamie Thomas and Nick Jones for

providing assistance throughout the data collection process.

ii

ABSTRACT

The purpose of this study was to investigate the effectiveness of varying training

interventions and exposures, over a 7 week period on elite athletes. The effects of

traditional strength training (TST, 80% of one repetition maximum [1RM], 4d/week), blood

flow restriction (BFR, 30% 1RM, 2d/week), combined TST and BFR (TST-BFR, TST

4d/week and BFR 2d/week) were analysed on measures of hypertrophy, strength and

power. Twenty seven elite athletes were randomly divided into the three training

interventions (TST n=9, BFR n=8 and TST-BFR n=10) in a test, re-test experimental

design. The increased thigh girth circumference and 1RM leg press strength in TST

(1.6cm/2.6% and 20kg/6%), BFR (2.1cm/3.7% and 21.2kg/6.6%) and TST-BFR

(3.2cm/5.1% and 39.9kg/11.7%) were all significant (p< 0.01) with a strong effect size for

each group (η2s> .800). Countermovement jump did not change significantly (p> 0.05) in

any of the aforementioned training interventions. The results suggest that BFRT could

provide supplementary benefits to TST in improving muscular hypertrophy and strength

when the two training modalities are combined in elite athletes. Furthermore, data

presented in the study suggests that BFRT can provide athletes with quick time course

adaptations in muscular hypertrophy and strength. Key words: muscle hypertrophy,

muscle strength, power, sport performance, resistance exercise, strength training,

ischemia, blood flow restriction, vascular occlusion, KAATSU, exertion, perception, elite

athletes.

22

CHAPTER I

INTRODUCTION

23

CHAPTER 1

INTRODUCTION

The appropriate application of a given training stimulus can cause positive skeletal muscle

adaptations (Schoenfeld, 2013). Central to the notion of physiological adaptation are

principles which manipulate frequency, overload and progression (Karabulut et al., 2007).

It is widely accepted that in order to elicit physiological adaptations the intensity exposure

must be manipulated to dictate the nature of a said given adaptation

(Raymond et al., 2013). A resulting factor in the dictation of exercise intensity causes

adaptations of musculature hypertrophy, strength, power and has been regarded as the

most influential factor in the prescription of training (de Salles, 2009). However, research

analysing transient intramuscular ischemic methods, such as blood flow restriction (BFR)

have used intensities between 20-50% of one repetition maximum (1RM) to elicit similar

adaptations to high mechanical loading intensities which exceed 80% 1RM. A growing

body of literature has supported the positive effects BFR has on physiological adaptations

(Pope et al., 2013), skeletal morphology and function (Loenneke et al., 2012). The

significantly low mechanical loading applied to BFR training (BFRT) challenges the notion

of training intensity being the most influential factor in achieving physiological adaptations

of musculature size and strength. Training intensities between 20-50% 1RM is seen as

optimal during BFRT which is contrary to prescriptions of optimal dynamic strength training

often being quantified as a function in excess of 80% 1RM (Wernbom et al., 2008).

The BFRT intervention has been in the literature since it was developed in the 1960’s

(Yamanaka et al., 2012). However, recently the training modality has been viewed as an

alternative to conventional heavy resistance training methods for eliciting a similar strength

and hypertrophic augmentation (Weatherholt et al., 2013). The BFR method restricts the

most proximal area of the limb which under certain pressures encourages arterial blood

flow to the exercising muscle, whilst occluding venous return invokes blood pooling

(Fahs et al., 2012). A substantial amount of work has focused on the methodological

applications of BFRT (Fahs et al., 2012; Loenneke et al., 2010; Loenneke et al., 2011a;

Loenneke et al., 2013). Published studies have assessed intensity ranges between 20-

50% 1RM (Abe et al., 2005; Cook et al., 2007; Wernbom et al., 2006), training frequencies

ranging from two days a week to twice daily (Abe et al., 2005a; Abe et al., 2005b; Clark et

al., 2011; Karabulut et al., 2011), restriction pressures ranging between 100-300 mmHg

24

(Abe et al., 2005a; Fujita et al., 2007; Fry et al., 2010; Takarada et al. 2000b; Wernbom et

al., 2006) and varying combinations of sets and repetitions (Abe et al., 2005a; Abe et al.,

2005b; Cook et al., 2007; Clark et al., 2011; Karabulut et al., 2010; Wernbom et al., 2006).

However, the optimal combination of treatment exposures is yet to be fully determined. To

date, there is no optimal approach to train under BFR despite varying researchers

suggesting guidelines (Fahs et al., 2012; Loenneke et al., 2011a; Loenneke et al., 2013).

Research into BFR has applied the training modality to varying populations such as

rehabilitating individuals, elderly, and untrained populations (Lejkowski et al., 2011;

Patterson et al., 2011; Ishii et al., 2005). Despite BFR literature being under researched as

a whole, research analysing elite populations training in combination with BFR is poorly

understood. However, as developments into BFR research progress, comparisons have

been conducted comparing BFRT to TST. The progression in research provided the scope

of the present study. The scope was to investigate the impacts combining both training

modalities would have on performance measures in an elite population. Therefore a

test- re-test experimental design was applied to the present study where TST, BFRT and

TST-BFR groups were tested on measures of muscle hypertrophy, strength and power.

The hypothesis of the present study was that all training interventions would have a

significant effect on changes in muscle hypertrophy and strength. However, power

determinants were only hypothesised to improve in the TST and TST-BFR groups.

Furthermore, it was hypothesised that the combination of TST and BFR would be an

effective training intervention elite athletes can implement into their training program.

Additionally, it was hypothesised that BFRT would be an effective short term stimulus

which elite athletes can utilise in order to achieve quick time course adaptations in

muscular hypertrophy and strength.

25

CHAPTER II

LITERATURE REVIEW

26

CHAPTER 2

LITERATURE REVIEW

Despite research providing evidence of increased mCSA between varying intensities of

1RM under BFR, it is unclear to what intensity elicits optimal increases in mCSA and

strength. Studies assessing BFR in combination with varying intensities include body

weight (Ishii et al., 2005; Yokokawa et al., 2008; Sumide et al., 2009), 20% 1RM

(Takarada et al., 2004; Takano et al., 2005; Yasuda et al., 2005; Nakajima et al., 2011;

Karabulut et al., 2011; Laurention et al., 2011; Yamanaka et al., 2012), 30% 1RM (Sata et

al., 2005; Madarame et al., 2008; Yasuda et al., 2010; Yasuda et al., 2011a; Yasuda et

al., 2011b) and 50% 1RM (Takarada et al., 2000; Takarada et al., 2002; Moore et al.,

2004). Therefore, intensity would appear to be an integral training variable to consider

when prescribing BFRT.

2.1 BFR mechanisms

Furthermore, when BFR is applied within a training intervention, there are many

mechanisms which cause a variety of physiological responses. Blood pooling during BFR

exposure causes a fluid shift induced through muscle cell swelling (Loenneke et al., 2012),

where as taking the occlusive stimulus off causes reactive hyperemia. Reactive hyperemia

occurs as a consequence of Raynaud’s phenomenon (Bakst et al., 2008). The

phenomenon transpires when there is a transient increase in blood flow following

ischemia due to the lack of oxygen availability and the build up of metabolites

(Cooke et al., 2005). Furthermore, ischemic reperfusion to the previously restricted muscle

is caused following the removal of an occlusive stimulus (Horiuchi et al., 2012).

The cell swelling response is caused by vasodilation and restoration of blood flow which

causes the pressure gradient needed to force the fluid shift from extracellular to

intracellular space (Loenneke et al., 2012b). The reperfusion of blood flow has been

suggested to stimulate positive effects on arterial compliance which is thought to be a

result of arterial sheer stress (Patterson and Ferguson, 2010). This is an important for long

term chronic adaptations, especially for athletes engaging in BFRT. Blood pooling and

reactive hyperemia alters the nature of local hepatocytes to become more anabolic

(Cermak et al., 2008). Muscle cell swelling has been postulated to cause the activation of

mTORC1 and MAPK signalling pathways when exercise is combined with BFR

27

(Thiebaud et al., 2014). Furthermore, the swelling of local hepatocytes induces the

capability to inhibit catabolism; this would inherently alter the protein balance towards

anabolism (Loenneke et al., 2012b).

Conversely, it has been postulated that cell swelling could be caused by inflammation or

muscle damage (Yasuda et al., 2010). However, data has been generated to suggest that

acute BFRT causes no change in muscle damage and oxidative stress markers (Abe et

al., 2005 Abe et al., 2006; Fujita et al., 2008). Therefore, quick time course adaptations in

musculature hypertrophy, following a period of BFRT is due to structural adaptations as

opposed to a result of muscle cell swelling driven by inflammation or muscle

trauma. Moreover, muscle cell swelling appears to be central to BFRT mediated

adaptations which coalesce with varying physiological mechanisms to generate a greater

hypertrophic potential following BFRT (Loenneke et al., 2012b).

Additionally, it has been documented that other factors influence this foundational

mechanism other than muscle trauma and inflammation. Such factors include BFR

causing hypoxic mediated conditions which augments an increased production of

intracellular metabolites (Pope et al., 2013). Intracellular metabolites, however small in

quantity, create an increased osmotic gradient which transiently influences muscle cell

volume (Loenneke et al., 2012b). There is also data to support an increased stimulation of

muscle protein synthesis (MPS) through the phosphorylation of downstream targets of the

mechanistic target of rapamycin (mTOR) pathway (Fujita et al., 2007; Fry et al., 2010;

Gundermann et al., 2012). A study conducted by Fujita et al. (2007) found that BFRT

marked a threefold increase in phosphorylation of ribosomal protein S6 kinase beta-1

(S6K1) which is a regulator of translation initiation and elongation (Hackney et al., 2012).

The findings of Fujita et al. (2007) are supportive of the data provided by Fry et al. (2010)

and Gundermann et al. (2012) because S6K1 is a downstream target of the mTORC1

pathway and therefore a net gain in protein synthesis would be evident once this pathway

is stimulated. Conversely, BFR studies have shown that in terms of factors influencing

protein degradation, such as mRNA transcripts (associated with proteolitic pathways) have

been shown to be downregulated further than that of control groups exercising at 20%

1RM without BFR (Manini et al., 2011). Consequently, a reduction in catabolic

mechanisms post exercise results in a net loss in the ratio between protein synthesis and

degradation. Additionally, comparing heavy resistance exercise to BFRT, a study

conducted by Kraemer et al. (1990) assessed the effects heavy resistance exercise would

28

have on plasma concentrations of GH and found a 100-fold increase. Conversely,

Takarada et al. (2000a) also examined the same effect but after the investigation of a BFR

intervention, the researchers found a 290-fold increase in plasma concentrations of GH.

However, the extent of how influential these systemic hormones are, in regards to the

anabolic response, is unclear (West et al., 2010). Additional mechanisms thought to be

responsible for the physiological adaptations from BFRT are the proliferation of muscle

cells as a consequence of reactive oxygen species (ROS) activation (Shimokawa., 2013).

It has been shown that in hypoxic conditions there is an increase in xanthine oxidase

activation occurring within the muscle (Korthius et al., 1985) which exposes reperfusion

and signal transduction of muscle growth from the activation of ROS (Takarada et al.,

2000a). Furthermore, studies such as Manini et al., (2011) and Laurentino et al., (2012)

have found evidence to suggest that BFR suppresses messenger ribonucleic

acid (mRNA) expression of genes which is supported by findings in a study conducted by

Nielson et al., (2012) who also found evidence that myogenic stem cells were augmented

when exercise was combined with BFR.

2.2 BFR and clinical populations

It is therefore clear why BFR and its positive adaptations have attracted a variety of

populations. Conversely, the concept of applying an occlusive stimulus (i.e. knee wraps or

pneumatic cuff) to restrict blood flow can be uncomfortable for a variety of populations

such as individuals going through rehabilitation. However, those concerning themselves

with rehabilitation and applying the training modality from a clinical standpoint have

specifically exploited the effectiveness of BFRT due to the low load alternative

(Lejkowski et al., 2011). Therefore, high intensity methods and the contraindications which

expose rehabilitating patients are avoided (Wernbom et al., 2009). Research and varying

case studies have examined patients after a variety of injuries such as anterior cruciate

ligament reconstruction (Lejkowski et al., 2011; Ohta et al., 2003; Tarakeda et al. 2000)

and osteochondral fractures (Loenneke et al., 2013). Data from the literature has provided

evidence, specifically from a case study conducted by Loenneke et al. (2012) that BFR

exposure can aid in the prevention of muscle atrophy.

29

Muscle atrophy and disuse atrophy is a common occurrence during post-surgical

rehabilitation and the outcome often leads to the inability to fully recover and therefore

increasing the risk of re-injury (Mendias et al., 2013). The case study by

Loenneke et al. (2012) provided evidence that not only was muscle atrophy avoided but

muscle mass was maintained with bone formation occurring just after 2d/week of 6 week

leg BFRT. The evidence provided is by no means conclusive with only one subject being

analysed during the case study. Furthermore, the formation and healing rate of bone

documentation cannot be said to have occurred as a result of BFRT. However,

researchers investigating the correlation between bone markers and BFRT have provided

data to suggest there is a positive correlation after the training exposure (Beekley et al.,

2005; Bemben et al., 2007; Karabulut et al., 2011). Nevertheless, a study conducted by

Kim et al. (2012) provided evidence that high intensity training was more effective than

BFRT in terms of eliciting a greater response in bone formation but as previously stated

there are contraindications with this training modality and rehabilitation. However, similar

findings are yet to be established within athletic populations. Moreover, combining BFR

and rehabilitation has proven to be a beneficial supplement and is evident in the literature

when applying the training exposure to elderly populations.

There is a substantial amount of research assessing BFR application towards the elderly

population due to the population’s incapability of sustaining the necessary mechanical

stress required to achieve muscular failure (Loenneke et al., 2011b). Studies which have

used elderly populations combining BFR with walking include (Abe et al., 2006; Iida et al.,

2011; Ozaki et al., 2011a; Ozaki et al., 2011b) and combining BFR with resistance training

(Yokokawa et al., 2008; Patterson et al., 2011; Karabulut et al., 2010; Karabulut et al.,

2011; Gualano et al., 2010). The data presented from the accumulated studies have

provided evidence to suggest that BFR can positively influence hypertrophy and

specifically strength adaptations within elderly participants. The studies range from

samples of 1-44 men and women aged 64.5 ± 10.5, training under BFR between

frequencies of 3 days a week over 4 weeks and 3 days a week over 12 weeks. Post

training interventions strength increases improved by 17.4% ± 3%, training consisted of

either 3 sets of 15 reps which was separated by 20s rest or 3 sets of 10 reps being

separated by 30srest. The data therefore concludes that BFR can be applied to this

particular population over TST methods where elderly populations maybe prone to

orthopaedic injuries (Pollock et al., 1991 and Roth et al., 2000). However, data increases

30

in the region of 17.4% in strength are unlikely to be found when analysing highly trained

athletic individuals.

2.3 BFR and healthy untrained populations

Conversely, research analysing healthy individuals engaging in intensities as low as 20%

1RM in combination with BFRT have accumulated data in the region of 3.0-20.3%

increases in muscle cross-sectional area (mCSA) (Ishii et al., 2005 and Takarada et al.,

2000). The range in data signifies the lowest and highest significant changes of mCSA

within the current literature. However, the method of training exposure is very contrasting

between the studies and therefore is reflected in the results. The significance of such

findings in terms of achieving the maximum potential of adaptations within a population

means that 3% in mCSA would be of less significance to a novice/elderly/rehabilitating

population in comparison to elite athletes who are already highly trained.

The training prescription administered by Ishii et al. (2005) recorded a 3% mCSA change

in thigh hypertrophy. The method contained 6 exercises, 2 body weight compound leg

exercises, squat and lunges within a circuit of 11 participants who trained 3/week over 8

weeks under BFR exposure. The BFR method, administered very low pressures (80-120

mmHg) resulting in venous return unlikely being occluded when compared to previous

pressure which have used (160-240 mmHg) during BFR of the thigh (Yasuda et al., 2005;

Takarada et al., 2004; Abe et al., 2006). Inadequate pressures combined with an

insufficient total volume of BFR leg exercise (1 or 2 sets with a total of 20-30 repetitions)

would be viewed by many BFR practitioners as a hindrance to substantial mCSA

development. It is likely that the volume was too low to produce a substantial accumulation

of metabolites which is seen to be an influential component to the adaptation process in

BFRT (Loenneke et al., 2012a). The BFR pressure applied in combination with a lack of

volume in BFR leg exercises would be the main factors in the minor increase of mCSA.

In comparison, Tarakeda et al. (2000a) administered a more effective protocol for

developing a more potent hypertrophic response. The study analysed 11 participants who

trained 2d/week over 16 weeks under an application of localised BFR which was more

concentrated to just the subdominant bicep when compared to the Ishii et al. (2005) study.

The training prescription contained 5 sets of 17.66 ± 1.5 repetitions which is a considerably

large volume when compared to the training prescription by Ishii et al. (2005). The

repetition range by Takarada et al. (2000a) was an average of completed set repetitions

31

which suggests the participants trained to failure. Training to failure is thought to be an

essential component in the prescription of achieving optimal strength and mCSA

adaptations when exposing participants to BFRT (Yamanaka et al., 2012). The training

volume over a significantly longer period combined with a high BFR pressure resulted in a

20.3% increase in muscle hypertrophy. Despite obvious differentiation between the two

muscle groups (thigh versus bicep), the data between the two studies is still very much

contrasting. The two methods contained a control group which either did no training or

were administered the same intensity without BFR. The control groups in both studies

achieved no significant change, concluding that the BFR exposure was the primary cause

of hypertrophy. The data presented from Takarada et al. (2000a) compared BFR at 30-

40% 1RM and compared the intensity exposure (30-40% 1RM) without occlusion.

2.4 BFR versus TST

There are varying definitions of TST and can be defined as a modality which involves

exercises that isolate specific muscles in order to increase strength more effectively and is

often quantified in excess of 70% 1RM (McGill et al., 2009; Alcaraz et al., 2011). The study

conducted by Takarada et al. (2000a) documented an 18.4% increase in bicep brachii

mCSA in the TST group. However, the BFR group increased their mCSA by 20.3%, so

therefore this study along with others within the literature comparing BFRT to TST, are

suggestive of the novel prospect that BFRT elicits similar to greater adaptations when

compared to TST.

Another study which has researched the difference between BFRT and TST was

conducted by Cook et al. (2012) who concluded that there was a high level of activation of

the higher threshold motor units (HTMU) when training under BFR which was similar to

that of TST methods. The researchers found that high mechanical loading (70% of peak

dynamic torque (PDT)) produced greater muscle activity than BFRT (20% PDT) before

and after 8 recreationally active male participants underwent testing. However, despite

BFRT demonstrating lower levels of muscle activation than TST methods; there were

comparable torque decrements between the groups. Conversely, the participants weren’t

resistance trained. Therefore, unlike elite athletes, accessing HTMU would be substantially

harder for untrained individuals (Walker et al., 2009).

32

The result of BFRT causes metabolite accumulation which leads to the recruitment of

HTMU (Loenneke et al., 2011b); consequently there is enhanced endocrine activity as a

result of HTMU augmentation (Abe et al., 2005; Madarame et al., 2008; Reeves et al.,

2006; Tarakeda et al., 2000a). It is recognized that HTMU’s have the greatest potential for

structural musculature morphology (Wagner, 1996). Many studies have researched BFR

and electromyography (EMG) (Hotta et al., 2011; Wernbom et al., 2009; Yasuda et al.,

2012; Manimmanakorn et al., 2013).

Manimmanakorn et al. (2013) assessed EMG activity and speculated that BFRT caused a

shift in the recruitment pattern from type I to type II motor units during exercise.

Furthermore this shift is possibly due to the stimulation of groups 3 and 5 afferents (Hayes

et al., 2009). Consequently, the stimulation results in the suppression of the alpha motor

neuron which innervates type 1 muscle fibers (Yasuda et al., 2010b). The study by

Manimmanakorn et al (2013) suggested that this was caused due to a decrease in the

concentration of oxygen in the BFR limb. Therefore, it can be suggested that the increase

in strength found in the BFRT group can be attributed to HTMU inauguration of the already

trained agonist muscles (Hakkinen et al., 1983). Despite the majority of data

demonstrating similar to greater adaptations found in BFRT compared to TST, the

samples used within the literature aren’t highly trained individuals and are certainly not

from an elite population.

2.5 BFR and athletic populations

Elite populations are significantly harder to study in comparison to other populations. A

major area in the BFR literature which needs to be addressed is whether BFR can

specifically aid hypertrophy, strength and power development in elite athletes (Yamanaka

et al., 2012). Firstly it is important to assess the characteristics elite athletes’ desire and to

establish whether such characteristics have been developed already within the BFR

literature. There is evidence of studies using highly resistance trained individuals and

athletes but there are no definitions indicting an elite status of samples used. The present

study defines the term of elite individual status as athletes who have competed nationally

or internationally in the past 3 years and are currently training under a national governing

body.

33

It is clear that BFR greatly increases musculature hypertrophy and strength. Researchers

within the BFR literature suggest that the modality has an accelerated time course of

adaptation compared to TST (Cook et al., 2013). However, muscular power is less

studied. A study which has focused on just neuromuscular adaptations was conducted by

Moore et al. (2004) who studied the effects BFRT at 50% 1RM over 8 weeks would have

on untrained men who trained 2d/week. The data presented found a 22% increase in

dynamic strength as well as a 51% increase in post activation potentiation (PAP), PAP is

the result of musculature activation prior to an activity which produces increased levels of

force generation (Esformes et al., 2011).

Force development and BFRT has undergone very little research. However, the current

research has suggested that neural adaptations of strength are not conclusive enough to

improve jump height performance (More et al., 2004). Such conclusions have also been

drawn by Abe et al. (2005) who conducted a study considering the influence the effects

BFRT would have on track and field college athletes but found no improvements in jump

height after twice daily BFR exposure sessions over a period of 8 days. The study

examined athletes who incorporated the training into their traditional sprint and jump

training. However, a major limitation was that the athletes trained for a period of only 8

days which can be argued that a training study on such a time would not allow for

developments in power adaptations. Converselt, the researchers documented a 10%

increase in 1-RM leg press strength and estimated an increase in skeletal muscle-bone

CSA of (4-5%). Despite combining BFR with traditional sprint, jump training and not

conventional TST, the findings provide an insight into the effects BFR has on highly trained

individuals. This at the time was a novel finding as these individuals are part of a

population which do not readily obtain structural determinants easily (Hakkinen et al.,

1987).

The findings found by Abe et al. (2005) were also found in a study conducted by

Madarame et al. (2011) who conducted a 10 week training study. The study prescribed

horizontal BFR squats 2d/week to examine whether this had an impact on jump

performance but again failed to record any significant changes in increased jump height.

This study examined untrained participants with no indication of the participants having

any previous squat experience. However, the experimental design augmented a 19.3%

and 8.3 increase in 1RM strength and mCSA. This study reflects the majority of research

indicating increases in mCSA being the main adaptation, this lends itself to max force

34

production which suggests that BFRT may be less effective in terms of developing neural

drive. Neural drive is associated with max rate-of-force development which is indicative of

the research conducted within rehabilitation settings where movements tend to be

performed in a more slow and controlled manner.

Recently a study conducted by Cook et al. (2013) examined 20 semi-professional rugby

athletes on measures of strength, power and salivary hormonal parameters over a 3 week

period. Athletes trained 3d/week during pre-season and participated in 5 sets of 5

repetitions bench press, leg squat, and pull-ups at 70% 1RM. The BFR group wore

occlusive cuffs around their proximal thighs only, whereas the control did the same training

intervention in a crossover design but without an occlusive stimulus. Once the training

exposure had been completed, the BFR versus control groups were compared and it was

found that improvements in squat (7.8 ± 2.1 vs 4.3 ± 1.4 kg), bench press (5.4 ± 2.6 vs 3.3

± 1.4 kg), leg power (168 ± 105 vs 68 ± 50 W), salivary testosterone (ES 0.84-0.61) and

cortisol responses (ES 0.65-0.20) were all greater in the BFR group. Despite greater

results in the BFR group compared to the control the data provided is not compelling. If the

results were more equivocal then BFRT would be a valuable stimulus during in season

training when combined at intensities (70% 1RM) used in TST. However, the data is not

suggestive of BFR being augmented with high loaded TST.

The results of Cook et al. (2013) demonstrate that despite lower body BFR, the group also

achieved greater bench press 1RM strength compared to the control group. This study

therefore is suggestive that a mechanism of a systemic origin assisted in the increase in

upper body strength. Systemic mechanisms were also postulated in a study conducted by

Yasuda et al. (2010a) who looked at how non-restricted trunk muscles are affected by

multi-joint BFRT. The study included 10 participants in total, 5 of which underwent training

twice daily, 6d/week for 2 weeks. The BFR group performed bench press at 30% 1RM with

training consisting of 4 sets with repetitions equating to 75 in total. The study was a test-

re-test experimental design with bench press 1RM strength, triceps brachii and pectoralis

major muscle thickness being assessed pre- and post-intervention. The training

intervention resulted in a significant increase in 1RM bench press strength in the BFR

group (6%) but not in the control (-2%). Muscle thickness in the triceps and pectoralis

major increased by 8% and 16% in the BFR group but not in the control group (-1% and

2%). The researchers suggest that the cause of non-restricted pectoralis major muscle

hypertrophy observed in the non BFR chest muscle, was caused due to acute increases in

35

endogenous anabolic hormones such as growth hormone and insulin growth factor-1 (IGF-

1). These suggestions derive from studies conducted by Abe et al. 2006 and Reeves et al.

2006.

Human growth hormone secretion is largely associated with exercise intensity and is

modulated in greatest amounts during high intensity exercise (Kraemer et al., 2002).

Conversely, BFR has been shown that the secretion of human growth hormone is equal to

or even greater than that produced during TST which exceeds 70% non-restricted 1RM

(Sato et al., 2005 and Reeves et al., 2006). However, despite consistent reports of

increased levels of modulating growth hormone concentrations within the BFR literature,

the direct role growth hormone plays, in regards to muscle morphology is equivocal (Cook

et al., 2013). Contrary, It is better understood that exercise induced growth hormone

production stimulates IGF-1 which directly impacts MPS and therefore impacting the rate

of muscle morphology (Borst et al., 2001).

The work by Yasuda et al. (2010a) used few participants who were not resistance trained.

However, there are studies which have assessed the application of BFR towards an

athletic population (Abe et al., 2005; Takarada et al., 2002; Wernbom et al., 2009; Cook et

al., 2012; Manimmanakorn et al., 2013). Conversely only two studies have claimed to have

studied an elite population and such studies were conducted by Takarada et al. (2002) and

Yamanaka et al. (2012). The study by Takarada et al. (2002) investigated 17 highly trained

athletes who had over 5 years resistance training. The study included an 8 week training

intervention where ‘elite’ rugby players participated in knee extensor muscle exercises at

50% 1RM with BFR (n=6), 50% 1RM with no BFR (n=6) and a control group which did no

training (n=5). The results concluded that when averaged over all velocities, the strength

increases of isometric torque after the training intervention were 14.3%, and 3.2% in the

BFR and non-BFR groups. The increase in mCSA reported in the BFR group increased by

12.3%, whereas no results were reported for the non-BFR group. Despite low numbers of

participants in each group the results provide evidence that BFR causes marked increases

of mCSA and strength in ‘elite’ athletes. However, there is no definition of elite or to what

level the rugby players played at so therefore, it is hard to determine the actual level of the

participants, albeit highly trained.

36

Conversely, a study driven by Yamanaka et al. (2012) studied National Collegiate Athletic

Association Division IA football players on determinants of muscular strength and

hypertrophy. The participants (n=32) were separated into BFR (n=16), non-BFR (n=16)

and trained 3d/week for 4 weeks. The intervention consisted of both groups, with or

without BFR doing 1 set of 30 repetitions on bench press and squat at 20% 1RM, followed

by 3 sets of 20 repetitions at 20% 1RM. The participants trained in their regular strength

off-season training program which preceded the experimental interventions. The

researchers found that the BFR intervention was effective for improving hypertrophy and

strength during off-season conditioning. The results concluded that the average 1RM

bench press increased by 7.0% in the BFR training group, which was significantly greater

than the 3.2% increase in the non-BFR group. A significant difference was also seen in

squat 1RM strength with the BFR group increasing on average 8.0% compared to 4.9%

increase in the non-BFR group. However, in terms of hypertrophy only chest girth

increased, whereas arm and thigh girths did not. Furthermore, the experimental

interventions of BFR and non-BFR were carried out straight after the athlete’s regular

strength off-season training program. Combing BFRT straight after a TST session may not

be the most optimal approach in terms of developing hypertrophy and strength

adaptations. It is important to recognise that there is a finite amount from which a muscle

can adapt to a given training stimulus (Atherton and Smith, 2012).

The method administered by Yamanaka et al., 2012) did not have athletes train to

exhaustion or failure. This could be the cause of no significant differences in arm and thigh

girths after 4 weeks of exposure. Another factor influencing no significant change could be

that the amount of BFRT exposures was insufficient. Conversely, the study analysed an

athletic population on measures of strength and hypertrophy. This provided the scope of

the present study of combining BFR-TST on measures of hypertrophy, strength, power

and whether the combination of the two training interventions can cause positive outcomes

on these determinants within an elite population.

37

CHAPTER III

METHOD

38

CHAPTER 3

METHOD

3.1 Experimental design

A total of 27 participants underwent a short term (7 week) training intervention where

participants were randomly assigned into 3 groups, a TST group (10), BFR group (8), and

a combined TST-BFR (9) group. The groups were designed to examine which training

intervention would be most effective in developing the greatest functional muscle

adaptations in elite athletes. To examine the possible training induced structural and

neural changes, tests of anthropometry, vertical jump and 1RM tests were performed

before and after training. Two groups were exposed to a BFR (BFR + TST-BFR) stimulus

and performed leg press exercise at an intensity of 30% 1RM. The TST group were not

exposed to BFR exposure and participated in their strength training method which was

prescribed at an intensity of 80% 1RM and was very much orientated around strength

adaptations. The same strength protocol was prescribed to the TST-BFR group, where

they were also exposed to TST at (80% 1RM) which was administered by the athlete’s

strength and conditioning coach. In order to supplement BFR with the TST protocol the

TST-BFR group supplemented BFR 2d/week with their current TST training program. The

TST and TST-BFR group engaged in the TST protocol 4d/week in a pre-competitive

strength phase during the study. To ensure methodological validity, each athlete was

assigned a consistent time to train by the strength and conditioning staff throughout the

intervention period. The athletes who engaged in TST in both TST-BFR and TST groups

were prescribed pre-competition strength training due to athletes competing in the

commonwealth games. The study simulated the training environment where athletes

prepared for a competition which in essence was post testing and therefore the study had

strong ecological validity.

3.2 Participants

Thirty male (n=23) and female (n=4) elite athletes, [age 24 (5) year; height, 175 (6.8) cm;

body mass, 73.2 (6.8) kg] volunteered to participate in this study. All athletes were of an

elite status, competing at national, international level and were currently training under a

national governing body. The inclusion criteria also required participants to have had

experience in resistance training for over a minimum of 5 years. The participants were

39

randomly assigned into 3 groups: BFR (n=8), TST (n=9) and TST-BFR (n=10). Participants

gave written consent to participate in the training study and were informed of the risks

associated with the type of training. The consent was approved by the Ethics Committee of

Cardiff Metropolitan University.

3.3 Height and body mass

The body mass index was calculated by dividing body mass (kg) by the square height

(m).The measurement of body mass was conducted so to the nearest 0.1 kg using a

Digital Scales (SECA- Model 770 Vogel &Halke, Hamburg, Germany). Participants wore

light workout clothing with no footwear during the data collection. Height was measured

using a stadiometer (Holtain Fixed Stadiometer, Holtain LTD, Crosswell, Crymych, Pembs,

UK) to the nearest 0.1 cm (Louman et al., 1998).

3.4 Measurements of hypertrophy

Measures of hypertrophy were assessed using anthropometric tape which measured thigh

girth circumference. Thigh girth was measured in centimetres and to the nearest 0.1cm

around both legs. Thigh girth was measured in the plane orthogonal to the long axis of the

thigh (Gobbo et al., 2012). A line was made from the superior edge of the patella to the

inguinal crease and a mark was made at the midpoint of this measure. The anthropometric

tape was then placed perpendicular to the long axis of the thigh around the point the mark

was made (Louman et al., 1998).

3.5 Measurements of strength

Maximum dynamic leg press 1RM strength was measured prior to testing. Participants

were allowed to warm up with a low load where 10-12 repetitions could be achieved

comfortably. After a 2 minute rest the load was increased to an estimated 80% prediction

of participant 1RM. Once a lift was completed successfully or when the participant used

correct form and completed the entire lift in a controlled manner without assistance the

load was increased by 5% until the participant failed to lift through the entire range of

motion. A safety mechanism was in place between the participant and weight to ensure

safety. Between sets a set period of 2–3 minutes of rest were given to the participants to

ensure an adequate level of recovery was met (Abe et al., 2000).

40

3.6 Measurements of power

Counter movement jump height was collected using a jump mat (Smart jump, Fusion

Sport, Brisbane, Australia) which assessed the levels of explosive muscular power during

pre, post testing and therefore the nature of adaptations during the training intervention.

Participants in all groups performed a counter movement jump 3 times with a 1 minute

period of rest in between each jump. The highest jump achieved was used in the data

analysis process.

3.7 Training protocol

One week prior to training participants engaged in an orientation session where force plate

data, anthropometric measurements and isotonic 1RM strength tests were carried out for

all subjects. Participants who were randomly assigned to either BFR or TST-BFR were

made to become familiarised with training equipment. BFR and TST-BFR groups became

accustom to exercising under BFR, whilst experiencing the pressures used to restrict

blood flow.

Participants performed 4 sets of dynamic bilateral leg press at 30% 1RM under BFR and

were conformed to the guidelines set by Fahs et al. (2012). After the completion of

individual sets participants were given 90’s of rest before proceeding onto subsequent sets

and each session lasted between 15-20 minutes with time under BFR being between 8-10

minutes. A constant and controlled method was used throughout the prescribed training

with intensity set at 30% of predetermined 1RM and volume consisting of 75 repetitions, 1st

set (30 reps), followed by a further 3 sets (15 reps). Once participants had finished the

final set, the occlusive stimulus was maintained for a period of 2 minutes before the cuffs

were removed, this was followed by an active cool down. The aim of the protocol was for

participants to fail at the upper limit of the rep range, if the participant completed the

session without failure then verbal feedback would enable for adequate loading during the

next session.

Repetitions consisted of all participants following the same protocol, initiating the

movement began with a deep breath and held during the descent phase until a depth

where the greater trochanter of the femur was lowered to an equal level to the knee and

therefore parallel to the leg press plate (McGuigan and Wincester, 2008). As soon as the

required depth had been reached the investigator delivered verbal feedback to the

41

participant and once received the accent phase began with a maximal and forceful

movement was initiated in order to engage the high end motor units (Gullich et al., 1996;

Young et al., 1993). Participants engaged in training with at least 24 hours in between

sessions.

3.8 Blood flow restriction

During the orientation session, one week before training, the TST and TST-BFR groups

were trained to wear an occlusive stimulus (Manual Blood Pressure Monitor, Yamasu,

Tokyo, Japan) at the most proximal portion of the upper legs. The blood pressure devise

was inflated between 120-200 mmHg (Fahs et al., 2011) depending on limb

circumference. The participants were told that the pressure should be tight but not at all

painful and it should be the build-up of metabolites causing the pain and not the blood

pressure devise itself, this resulted in a varied range in the pressures applied. Once an

appropriate pressure was found this pressure was maintained throughout the entire

session. Due to the nature of the devise, during working sets the pressure would deviate

by roughly 5%. However, during inter-set rest times the occlusive cuff was pumped to the

desired pressure.

3.9 Rating of Perceived Exertion (RPE) and Rating of Perceived Sensation (RPS)

During the training protocol, after all 3 groups (BFR, TST, TST-BFR) performed each

subsequent set; RPE was assessed with a customised Borg scale. The customised Borg

RPE scale provides greater validity as colour, emoticon, verbal cues are used and

previous studies have shown this method to be more effective than other RPE measures

(Bijur et al., 2001 and Bulloch et al., 2009). The method used is comparable to Borg’s RPE

original method (Borg, 1998), however the participants were asked to look at a customised

chart and point on the scale instead of calling out a number.

RPS unlike RPE, was conducted after each set. The participants were asked to rate the

sensations of pressure, burning, aching, and pins/needles in their legs and surrounding

areas of the BFR devise. This method was devised by Weatherholt et al. (2013) and used

a modified Borg CR-10 pain scale with the addition of colour and emoticons which has

been found to be most effective by individuals engaging in BFR.

42

Figure 2. A visual analog developed by Weatherholt et al. (2013) to analyse athlete rate of

perceived exertion and rate of perceived sensation. The scale was utilised throughout the

data collection process to assess the BFR and TST-BFR group RPE and RPS.

3.10 Statistical Analysis

The statistical process of analysing the data and training variables was analysed using

statistical software (IBM SPSS 20; IBM Corp, New York, Armonk).The three training

interventions were analysed by an ANOVA, followed by post hoc testing using Bonferroni’s

method and the statistical significance was set at an alpha value of (p<0.05). Cohen’s

effect size was used to determine the magnitude of the partial eta-squared values (η2s).

43

Figure 2.Schematic representation of the studies experimental design.

44

CHAPTER IIII

RESULTS

45

Variable

Pre Post Pre Post Pre Post

Height (cm) 173.9 ± 5.3 173.7 ± 5.8 177.4 ± 6.8 177.2 ± 5.4 173.7 ± 6.7 173.9 ± 6.8

Weight (kg) 72.8 ± 7.1 173.7 ± 5.9 74.1 ± 6.4 74.5 ±7.4 72.9 ± 6.3 73.2 ± 5.9

Note: Values are mean with standard deviation (SD).

TST BFR TST-BFR

Table 1. Physical characteristics

Variable TST BFR TST-BFR

Pre Post Pre Post Pre Post

59.2 ± 3.2 60.6 ± 3.4* 54.4 ± 4.9 56.5 ± 5.1* 58.9 ± 1.8 61.9 ± 1.9*

59.3 ± 3.5 61.1 ± 3.7* 55.0 ± 5.0 57.1 ± 5.2* 59.2 ± 2.4 62.5 ± 2.4*

38.7 ± 10.0 39.9 ±10.1 39.3 ± 6.6 39.8 ± 6.3 34.2 ± 4.1 35.9 ± 4.3

317.2 ± 54.5 337.2 ± 57.7* 99.0 ± 57.7 320.2 ± 61.8* 302.0 ± 83.0 341.9 ± 94.5*

Note: Values are mean with standard deviation (SD). * Signifcant difference (p < 0.05).

mCSA [Left] (cm)

mCSA (Right] (cm)

1RM Leg press (kg)

Countermovement jump (cm)

Table 2. pre- and post-test data of strength, power and girth measures by training intervention.

CHAPTER 4

RESULTS

There was no significant difference (p> 0.05) in height or weight in any of the training

interventions (Table. 1).

4.1 Changes in thigh girth

The mCSA [left] and mCSA [right] increased significantly (p< 0.01) in the TST group

(Table. 2).The significant change was seen between pre- and post-test where the TST

group increased mCSA [left] by (1.4cm/2.3%) and mCSA [right] by 1.8cm/2.9%). The BFR

group increased mCSA [left] and mCSA [right] by (2.1cm/3.7%), respectively. The

increased change in thigh girth in the BFR group was of significance (p< 0.01). The

TST-BFR group also had a significant increase (p< 0.01) in mCSA [left] and mCSA right].

The mCSA [left] increased significantly by (3.0cm/4.8%) and mCSA [right] by

(3.3cm/5.2%), respectively.

The within subject test for mCSA [left] indicated that irrespective of group, the main effect

for time was significant (F1,2 = 49.4, p< 0.01). The main effect for mCSA [right] was also

significant (F1,2 = 39.1, p< 0.01). The change in performance, over time per group

indicated that the group*time interaction was significant (p< 0.01) for mCSA [left] and

46

[right]. Post hoc analysis using the Bonferroni test demonstrated that the mCSA [left] from

pre- to post-test was significantly different (p< 0.05) between TST and BFR intervention.

The BFR and TST-BFR intervention was also significantly different (p< 0.05). The TST and

TST-BFR groups demonstrated no significant difference (p> 0.05) between the two

training interventions. The mCSA [right] post hoc analysis using the Bonferroni test

indicated no significant difference (p> 0.05) between, TST, BFR and TST-BFR groups.

4.2 Changes in 1RM strength

The 1RM strength improved significantly (p< 0.01) in the TST group (Table. 2). The

significant increase was seen between pre- and post-testing where the TST group

increased 1RM strength by (20kg / 6.0%). The BFR group also improved 1RM strength

significantly (p< 0.05) and increased 1RM strength by (21.2kg/6.6%). The combined

TST-BFR group increased 1RM strength by (39.9kg/11.7%) and was significantly different

(p< 0.05) between pre- and post-testing.

The within subject test for 1RM strength demonstrated that irrespective of group, the main

effect for time was significant (F1,2 = 17.7, p< 0.01). The change in performance, over time

per group indicated that the group*time interaction was significant (p< 0.01) for 1RM

strength. Post hoc analysis using the Bonferroni test demonstrated that 1RM from pre- to

post-test was not significantly different (p> 0.05) between TST and BFR intervention. The

BFR and TST-BFR intervention was not significantly different (p> 0.05). The TST and

TST-BFR groups also indicated no significant difference (p> 0.05) between the two

training interventions.

4.3 Changes in countermovement jump height

The CMJ height improved in the TST group between pre- and post-testing by

(1.2cm/3.0%). However, this was achieved with no significance (p> 0.05) (Table. 2). The

BFR group increased CMJ height by (0.5cm/1.2%). However, the increase in height had

no significant value (p> 0.05). The TST-BFR group also had no significant difference

between pre- and post-testing with increases of (1.7cm/4.7%). The within subject test for

CMJ height indicated that irrespective of group, the main effect for time was not significant

(F1,2 = 0.1, p> 0.05). The change in performance, over time per group indicated that the

group*time interaction was not significant (p> 0.05) for 1RM strength.

47

4.4 Training variable effect size in TST, BFR and TST-BFR groups

The effect size as seen in (Table. 3) demonstrates the magnitude in effects size the

training interventions had on training variables. The mCSA [left] signified a large effect size

(η2s> .8) for groups TST, BFR and TST-BFR. The mCSA [right] for groups TST, BFR, and

TST-BFR had a large effect size for all groups (η2s > .8). The effect size for 1RM strength

also showed a large effect size (η2s> .8) for groups TST, BFR and TST-BFR. The BFR

and TST-BFR demonstrated low effect sizes for CMJ height (η2s < .2) with the TST group

showing a moderate effect size (η2s > .2).

4.5 RPE and RPS scores

The RPE scores for BFR and TST-BFR groups were not significantly different (p< 0.05).

The mean RPE scores for the BFR and TST-BFR group during the warm up was (8.1 and

8.8), respectively. The first set (30 repetitions) generated RPE scores (for BFR and TST-

BFR (12.5 and 11.9). The RPE after the second set (15 repetitions) provided scores of

(14.8 and 15.6) for the BFR and TST-BFR groups. The third set (15 repetitions) collated

scores for the BFR and TST-BFR group of (17.4 and 17.0). The final set (15 repetitions)

generated RPE scores of (18.7 and 18.3) in the BFR and TST-BFR groups. The means

were averaged over each of the 14 BFRT exposures. The RPS data seen in (Appendix. 2)

demonstrates the mean recordings of all subjects who participated in the BFR and TST-

BFR groups, respectively. The average BFR session RPS did not increase significantly

throughout the training interventions. However, the athletes did experience a somewhat

strong pressure and aching sensation throughout the BFR exposures. Burning was also a

moderate sensation experienced with a somewhat very weak experience of pins/ needles.

Variable

TST BFR TST-BFR

mCSA [Left] (cm) .862 .923 .964

mCSA [Right] (cm) .895 .912 .964

Countermovement jump (cm) .021 .004 .033

1RM Leg press (kg) .738 .717 .907

Note: Results generated by Partial eta Squared (η2s).

Table 3. Effect size on pre- to post-test training variables.

Effect size (η2s)

48

CHAPTER V

DISCUSSION

49

CHAPTER 5

DISCUSSION

5.1 Main findings

The purpose of the present study was to examine the effectiveness 7 weeks of varying

training interventions would have on muscular hypertrophy, strength and power in elite

athletes. Furthermore, due to the difference in group training exposures, a secondary

question postulated the effects a dose type response would have on the three

performance measures. Training exposures were administered to the TST group (28),

BFR (14) and TST-BFR (42). The results of the present study support the original

hypothesis that all training interventions would have a significant effect on changes in

muscle hypertrophy and strength. However, the present study does not support the

hypothesis that the TST and TST-BFR training interventions would improve power.

Furthermore, data from the present study supports the integration of BFRT into a TST

program. Combining TST and BFRT was an effective intervention in providing significant

increases in muscular hypertrophy and strength. Additionally, it was hypothesised that

BFRT would be an effective short term stimulus which elite athletes could utilise to achieve

significant developments in muscular hypertrophy and strength. This hypothesis of BFRT

providing elite athletes with quick time course adaptations was evident in the present

study.

5.2 BFRT intervention

The present study can be considered novel in the respect that all athletes were of an elite

status compared to previous studies which have investigated BFRT (Abe et al., 2005; Abe

et al., 2006; Cook et al., 2007; Fujita et al., 2007; Madarame et al., 2008; Reeves et al.,

2006; Takarada et al., 2000; Yasuda et al., 2006). However, despite an elite training

status, the BFR group (30-50% 1RM) significantly increased (p< 0.01) mCSA

(2.1cm/3.7%) and a concomitant increase (p< 0.01) in 1RM strength (21.2kg/6.6%). The

significant changes observed are relatively high considering the athletes were of an elite

training status and would have already obtained a high degree of musculature hypertrophy

and strength. The increase would not have been achieved at intensities as low as 30-50%

1RM without BFR (Yamanaka et al., 2012). It can therefore be suggested that BFRT can

indeed be an effective stimulus for elite athletes. However, it is important to consider the

varying training exposures the athletes were prescribed BFRT over the 7 weeks. The BFR

50

group were exposed to just 14 sessions which is a small dose of training but caused a

significant increase in mCSA and strength.

Administering minimal training exposures and achieving significant changes in muscle

adaptation enables athletes to become exposed to an accelerated super-compensatory

training intervention (Abe et al., 2005). Decreasing the time athletes achieve the

super-compensatory phase of training is accelerated when the training exposure elicits

minimal fatigue and recovery (Mitsumune et al., 2013). The athletes were given an

effective training stimulus whilst obtaining sufficient rest in-between training sessions

(Kraemer, 2000). Minimal fatigue and recovery is evident in the BFR literature (Abe et al.

2005), despite early literature suggesting inflammation and muscle damage is a product of

BFRT which causes acute increases in cell swelling (Yasuda et al., 2010). Additionally, the

aforementioned mechanism as previously mentioned in the study can be influenced by

other factors other than muscle trauma and inflammation. During the present study, the

nature of BFRT would have caused hypoxic conditions, distal to the occlusive stimulus.

The hypoxic environment within the exercising muscles would have increased the levels of

intracellular metabolites (Colgan et al., 2012). Intracellular metabolites would have created

an increased osmotic gradient which would have transiently increased muscle cell volume,

signalling an anabolic response (Loenneke et al., 2012b).

The present study utilised the method of prolonging BFR after BFR. This was done to fully

exploit the reactive hyperemia response and increase the extent of metabolite

accumulation. However, it is important to note that despite increasing the reactive

hyperemia mechanism, hepatocytes have a finite ability to increase in cell volume

(Calloe et al., 2005). Therefore, prolonging BFR may not have increased an anabolic

response further than removing the occlusive stimulus immediately post exercise.

However, reactive hyperemia induced muscle cell swelling during BFRT has been

postulated to cause the activation of mTORC1, MAPK signalling pathways (Thiebaud et

al., 2014) and inhibit catabolic mechanisms; this would inherently alter the protein balance

towards anabolism (Loenneke et al., 2012b) causing muscle hypertrophy in the BFR

group. Mechanisms such as cell swelling have been suggested to be influential to BFR

induced adaptations within a short period of training exposure (Thiebaud et al., 2014).

Providing an effective stimulus with minimal exposure to training could potentially aid

athletes becoming exposed to overtraining.

51

Overtraining is a serious issue for many athletes, with many seasonal competitors

generally avoiding high intensity strength interventions during competitive periods to

circumvent overtraining (Abe et al., 2005). Therefore, BFRT could be a beneficial stimulus

to athletes who have to tolerate high levels of training intensity with heavy loading during

competitive periods. Recovery time is directly correlated to the likelihood of overtraining

(Kellman, 2010). However, BFR causes less muscle damage than TST, whilst obtaining

comparable physiological adaptations (Takarada et al., 2000). Consequently, it can be

suggested that the present study demonstrated an effective stimulus which elite athletes

can implement through their training program on days where a psychological break and

recovery from high intensity TST is needed. In addition, It has been suggested that TST

would not have readily caused a marked increase in musculature size and strength in

athletes in such a short time scale compared to BFR (Abe et al., 2005; Hakkinen et al.,

1987; Takarada et al., 2002; Yamanaka et al., 2012).

5.3 TST intervention

Conversely, the TST group did in fact achieve similar results to that of the BFR group

despite suggestions otherwise. The TST group significantly increased (p< 0.01) mCSA

(1.6cm/2.6%) and strength (p< 0.01) (20kg/6.0%). However, it would be misleading to

state that this was achieved similarly to the BFR group. The TST group participated in

twice as many training sessions as the BFR group (28 vs 14). Therefore, it can be

suggested that in terms of achieving increased mCSA and strength that comparable, if not

greater levels of physiological adaptations can be achieved with half the training

exposures when doing BFRT compared to TST. This also points towards BFRT having a

quicker time course to adaptation compared to TST. Quicker time course to adaptation

observed in BFRT compared to TST could be due to increased levels in endogenous

hormones observed in BFR research compared to TST. Plasma concentrations of GH

after TST have been found to increase by a 100-fold (Kraemer et al., 1990) compared to a

290-fold increase after BFRT (Takarada et al., 2000a). The greater endogenous response

observed in BFRT could possibly have caused the greater effect size observed in the BFR

group in the present study.

However, that does not suggest that over longer periods, BFRT would be more effective at

producing increased mCSA and strength further than TST. More research is needed to

better understand BFRT and warrants further exploration. Research into BFRT is

continuously emerging with awareness of the training protocol ever increasing throughout

52

scientific research, orthopaedics and the fitness industry. This has steered a section of the

research to explore the next progression of comparing BFRT to TST. Therefore, this study

took this progression a step further. The present study not only compared but also

contrasted the effects of BFRT and TST to see whether BFR can be supplemented with

TST.

5.4 TST-BFR intervention

The data presented from this study demonstrates that 7 weeks of TST-BFR caused a

significant (p< 0.01) increase in mCSA (3.2cm/5.1%) and strength (39.9kg/11.7%). The

data presented suggests that TST can in fact be combined with BFR effectively. Moreover,

it can be suggested that if an athlete does BFRT on its own, TST on its own or

supplements both interventions together then that athlete can expect to see an increase in

mCSA and strength. Additionally, that athlete may get a greater effect by combining

TST-BFR. However, in the construct of a competitive season, if an athlete can achieve a

significant improvement in strength and mCSA from just 14 sessions vs 42, the difference

in effect size increase in strength by 21.2kg or an increase in strength by 39.9kg comes

down to whether an additional 18.7kg improvement in the mean is worth a further 28

sessions.

Conversely, an athlete can never be too strong in terms of desiring the greatest strength

adaptations. In that regard the data demonstrates a greater significant increase in strength

from the TST-BFR group. However, whilst the data has not shown a significant

improvement (p> 0.05) in power, the TST training was a strength orientated mesocycle.

There is a compelling amount of data to suggest that strength is correlated to increased

levels of power (Aagaard et al., 2002; Baker et al., 2001; Cormie et al., 2010).

Furthermore, it could be that the athletes who participated in the TST-BFR group could

well achieve a greater carry over effect when transferring over to a power phase in their

training program. This can be suggested because the athletes built up more strength,

which could lead to an experience in a delayed training effect for rate of force

development. Additionally, because the training program was geared around strength,

then strength was the specific adaptation. The specific adaptations imposed demands

principle (SAID) states that a muscle will adapt to the imposed demands (Bandy and

Saunders, 2001). Furthermore, the TST-BFR group were prescribed more training

exposure than the other groups. Despite increased exposure, it is important to note that

53

because of the relationship between strength and power, a knock on effect in the next

mesocycle block could elicit greater enhancements in power.

There was a significant difference (p< 0.01) in mCSA between pre and post testing.

However, there are limitations to the procedures of obtaining mCSA. Anthropometric tape

was used so therefore the increased measure of thigh girth does not give an insight of the

composition of the change. The increase in mCSA only demonstrates an insight to

structural changes because there was no significant difference (p> 0.05) in power

development. However, it can be suggested that increased mCSA was evident due to

architectural as opposed to neural changes. Architectural changes can only be assumed

because in the present study there was no mechanical assessment of pennation angle,

muscle size or tendon size and therefore architectural change can only be suggested.

Similarly, it can be suggested that adaptive neural changes were not a product of any of

the prescribed training interventions. This can be suggested because there was no

significant improvement in power, which is suggestive in terms of rate coding, motor unit

recruitment and firing frequency that these neural components did not necessarily come

into effect.

5.5 Comparison of training intervention

The data presented demonstrates that all three interventions significantly increased

(p< 0.01) mCSA and strength. However, a compelling amount of data suggests that a

change in strength as a result of TST is due to neural adaptations (Arazi et al., 2013;

Schoenfeld, 2010; Zarezadeh-Mehrizi et al., 2013). Conversely, it can be suggested that

the predominant change as a result of BFRT is due to structural changes. However, it is

unclear what the underpinning physiological adaptations that BFRT elicits (Loenneke et

al., 2011b).

In the present study it can be suggested that BFR and TST produced architectural muscle

changes due to the significant increases (p< 0.01) in mCSA. However, it cannot be

suggested that either TST or BFR group developed any neural adaptations due to no

significant difference (p> 0.05) in power. However, there is a compelling amount of data

suggesting TST provides neural adaptations (Arazi et al., 2013). Conversely, there is

evidence to suggest that marked increases in mCSA and strength seen in BFRT, despite

low level of force generation, is due to HTMU’s becoming exposed during training

(Yasuda et al., 2004). It is evident from the present study that both modalities can be

54

utilised together as part of an effective training program. The TST-BFR group despite

greater exposures demonstrated the greatest results in terms of increases in strength and

mCSA. It can be suggested that a combination of neural and structural adaptations would

be augmented during a combined training intervention despite the present study

suggesting otherwise. Conversely, combining both approaches would be viewed as

optimal as it can be suggested that an athlete would obtain both structural and neural

adaptations, whilst achieving a large mCSA and strength effect.

5.6 BFR effects on RPE and RPS

It is apparent that from the range of SD of subject RPE (Figure. 3), athlete perception and

tolerance is diverse with many athletes achieving ratings similar to untrained subjects in

previous studies (Hollander et al., 2010; Wernbom et al., 2006; Wernbom et al., 2009;

Weatherholt et al., 2013). Therefore, from this data it can be concluded that the RPE from

BFRT is not different between populations and not dependant on training status. However,

it should be noted that during the present study the load was progressively increased to

ensure that repetition ranges were attained and achieved with maximal effort. When

comparing protocols where athletes trained at a constant BFRT intensity throughout

training compared to protocols where there was a linear progression of 1RM training

intensity it is apparent that linear progression of percentage 1RM is more desirable as it

ensures training until failure (Moore et al., 2004; Takarada et al., 2000b; Takarada et al.,

2002; Takarada et al., 2004). There is evidence to suggest that when BFR percentage

1RM is maintained, decreases in RPE ratings are seen and this is due to improvements in

metabolic adaptations such as increased concentrations of myoglobin and increased

mitochondrial activity that occur with hypoxic training (Manimmanakorn et al., 2013).

However, as seen in the present study, athlete endeavour was continuously challenged

which reflects the constant high RPE documentation and this was not a novel method

used in the present study (Karabulut et al., 2010; Karabulut et al., 2011). Furthermore,

another reason for the progression was due to the validity of the 1RM test. During pre- test

1RM tests, it is not certain that the results were a true reflection of athlete’s absolute 1RM.

The present study based the research around practical applications which athletes could

use. Furthermore, the application of an occlusive stimulus in the present study appeared to

achieve a desirable BFR pressure based on RPE and RPS scores. However, it has been

suggested that BFRT would be limited and would not appeal to highly motivated athletes

(Wernbom et al., 2008). Moreover, exercise intensity has been shown that exceeding

55

comfort zones during exercise results in poor adherence (Williams et al., 2008).

Conversely athletes constantly push through their comfort zones in training sessions

(Almagro et al., 2010) and despite high RPE scores the RPS ratings would suggest that

athletes coped well with the occlusive stimulus with no real factor apart from pressure

causing too much of a concern. The present study demonstrated an effective way for

athletes and coaches to track perceptual effort and pain which is in conjunction with

Hollander et al. (2010). Furthermore, this study recruited a sample size which was greater

than the majority of that seen in the BFR literature (Abe et al., 2005; Abe et al., 2006;

Fujita et al., 2007; Madarame et al., 2008; Reeves et al., 2006; Sakamaki et al., 2008;

Sato et al., 2005; Takano et al., 2005; Takarada et al., 2000; Yasuda et al., 2006) and

therefore can be considered as being high in validity.

5.7 Practical implications

It can be suggested that if an athlete does BFRT on its own, TST on its own or

supplements both interventions together then that athlete can expect to see an increase in

mCSA and strength. Additionally, a greater effect can be achieved by combining

TST-BFR. However, utilising the approach from the present study needs to be done with

caution as different training exposures were used. Therefore, in the construct of a

competitive season, if an athlete can achieve a significant improvement in strength and

mCSA from just 14 sessions vs 42, the difference in effect size increase in strength by

21.2kg or an increase in strength by 39.9kg comes down to whether an additional 18.7kg

improvement in the mean is worth a further 28 sessions.

Moreover, due to the time course of adaptations suggested in BFRT and adaptations in

mCSA and strength being achieved quicker than TST, it could be argued that vascular

angiogenesis may not occur on such a short time scale. Therefore, if an athlete was to use

BFRT in isolation then TST or TST-BFR should be resumed to elicit vascular adaptations.

Additionally, despite no study suggesting this method, it is well documented that TST

increases angiogenesis (formation of new blood vessels) (Gavin et al., 2007).

Furthermore, the adaptations obtained in mCSA and strength from just 14 sessions of

BFRT can provide athletes with an effective stimulus that can be utilised when coming

back from a long period of no training or injury. This study has provided data to suggest

that only 14 exposures can provide a large effect on increases in mCSA and strength with

low mechanical stress.

56

The present study demonstrated an effective stimulus which athletes can implement

through their training program. Furthermore, it can be suggested that BFRT could be used

on days where a recovery from high intensity TST or perhaps a psychological break from

TST is needed. Additionally, the present study demonstrated an effective way for athletes

and coaches to track perceptual effort and pain which is in conjunction with Hollander et al.

(2010).

57

CHAPTER VI

CONCLUSION

58

CHAPTER 6

CONCLUSION

6.1 Main findings

In conclusion, training induced increases in thigh girth and 1RM dynamic strength can be

achieved significantly when training under a TST, BFR and combined TST-BFR

intervention. The results in the present study suggest that 14 BFRT exposures over a

period of 7 weeks can significantly improve musculature hypertrophy and strength in elite

athletes. Acknowledging the differences in exposures, athletes can achieve similar

musculature adaptations when combining exercise with BFR in comparison to TST but

with half the training exposures. This is a valuable stimulus athletes can accentuate and

utilise during a competitive season. Furthermore, BFR and TST can be combined

effectively to enhance performance measures without a said given loss in performance.

However, with such an increase in performance measures, it is achieved at the cost of

significantly more training exposures. The combined training intervention would have

initiated a neural, hormonal and metabolic influence in achieving the aforementioned

adaptations (Takarada et al., 2002). In order to get a greater perspective of which

intervention is more effective in improving performance measures, an equal amount of

training exposures need to be prescribed. However, the reason the present study did not

do this was because the focal point of the research was directed towards athlete’s

performance levels versus a dose type response in training exposures. Furthermore, the

training modes were successful in improving mCSA and strength. However, the same is

not true for power. It can be suggested that there was no significant improvement in power

due to insufficient training stimulus or a lack of power-orientated exercise selection.

6.2 Limitations of the study

A limitation of the present study is that obtaining the mCSA and strength performance

measures was obtained using a 1RM leg press machine and anthropometric tape. Utilising

these methods can only give an insight and not a true reflection of the changes that have

occurred physiologically. Additionally, another limitation is that body composition was not

assessed and therefore differentiation during thigh girth measurement cannot be said to

have been due to increased muscle morphology. Furthermore, the exposures

administered to the groups were different which doesn’t allow the question to which

intervention is more effective to be answered. However, this method was an important

59

area to research in terms of developing an effective training system. This system provides

an insight athletes can use and implement into their training programs to develop the

greatest training stimulus. Another limitation to the present study is that the occlusive cuff

was not a purpose built devise to provide BFR. However, the cuff provided an effective

method for controlling pressure and provided an effective stimulus for eliciting adaptations

in mCSA and strength.

6.3 Future directions for research

Future research should focus on the effectiveness BFRT has during different stages of an

athlete’s periodization program. Such periods include, pre-season, de-loading and

recovery periods. Furthermore, research should investigate whether the combination of

TST-BFR has a delayed carry-over effect on developments of power as this was an area

not evident in the present study. Moreover, research should focus on developing a follow

up study to analyse whether adaptations achieved as a result of BFRT are sustained after

a washout period. This should be conducted on BFRT in isolation or during a combined

intervention as done in the present study. The effect BFRT has on arterial sheer stress is

poorly understood and research should focus on the vascular adaptations of the training

modality. Studying vascular adaptations in combination with BFRT would provide an

insight into whether BFRT adaptations can be sustained. Moreover, the mechanisms

behind the adaptations caused by BFRT are under researched and needs further

investigating. A longitudinal study should assess the long term implications of chronic

BFRT training over a prolonged period, assessing the safety and adaptations the

intervention elicits.

60

CHAPTER VII

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61

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CHAPTER VIII

APPENDICES

A1

ppendix 1. Ethics status

A2

CHAPTER 8

APPENDICES

Appendix 2. BFR session plan.

A3

Appendix 2. A visual analogue to measure athlete’s rate of perceived sensation.

Weatherholt et al. (2011)