10Petrofsky-vol5no4 12/19/05 7:20 PM Page 553 for ... · The side benefit of resistance train-ing...

The Journal of Applied Research • Vol. 5, No. 4, 2005 553

A Bidirectional Resistance Devicefor Increasing the Strength andTone in Upper Body Core Musclesand Chest Girth

Jerrold Petrofsky, PhD*Michael Laymon, DPTSc†Maria Cuneo, MPT*Jennifer Hill, BS†Amy Morris, BS†Russell Dial, MPT*Ashley K. Pawley*

*Department of Physical Therapy, Loma Linda University, Loma Linda, California†Department of Physical Therapy, Azusa Pacific University, Azusa, California

extend an exercise device 5 days perweek for a period of 1 month. At thebeginning and end of the study, musclestrength, muscle tone, and girth weremeasured on the chest and back with atensionometer and by a measuring tape.Ultrasound was used to measure musclethickness on the chest and back.

In the control group, there was nosignificant difference in the first andsecond measurements. In the experi-mental group, strength of the shoulderhorizontal adductors increased from23.0 ± 6.3 to 29.1 ± 8.5 kg. Shoulder hor-izontal abductors, in a similar manner,increased from 24.3 ± 9.1 to 31.4 ± 9.4kg. Associated with that increase wasan increase in chest firmness from 0.89± .29 kg to depress the chest to 1.16 ±0.29 kg. Back firmness improved by 0.35± 0.11 kg. Optical measurements of thechest wall showed an upward lifting ofthe breasts from the beginning to theend of the exercise period. In inches,initial chest girth was 36.4 (92.5 cm),

KEY WO R D S : e x e r c i s e, t o n e, e x e r t i o n ,t r a i n i n g

ABSTRACTConsiderable muscle weakness in theupper body is associated with the agingprocess. This can lead to upper andlower back strain and significant shoul-der disabilities. A new type of portableexercise device was tested for strength-ening and toning core muscles in theupper body such as the pectoralis major,pectoralis minor, and upper back exten-sor muscles, as well as scapular retrac-tors. Two groups of subjects wereexamined using single-blinded, random-ized study design. The control group(n=32) was examined twice to assess thereliability of the measurements; they didnot exercise. Twenty-nine subjects par-ticipated in a 1-month exercise programinvolving 5 minutes of flexion/extensionand horizontal abduction/adductionexercise using the arms to compress and

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Vol. 5, No. 4, 2005 •The Journal of Applied Research • Vol. 5, No. 4, 2005

increasing to 37.2 inches (94.5 cm) aftertraining. Muscle thickness increased by0.26 ± 0.12 cm on the chest and 0.05 ±0.12 cm on the back. Correspondingly,overall bust circumference increased by1.95 ± 0.8 cm measured 6 cm below theaxilla. The results showed that only 5minutes of exercise per day on a resist-ance trainer can cause dramatic effectson core muscle strength, firmness, girth,and toning of the upper body.

INTRODUCTIONStrength training involving resistanceexercise can have dramatic effects onpreventing the loss of muscle strengthand increasing muscle tone both inyounger and older adults.1 With resist-ance exercise, muscles respond withindays showing an increase in both toneand muscle strength.2 These types ofexercise not only have a general benefitof increasing muscle strength ande n d u r a n c e, but can also increase oxida-tion of lipids, reduce body weight, r e d u c elow-density lipoprotein cholesterol in theb l o o d , and reduce fasting glucose.3 - 5Lifting weights slowly against a heavyl o a d , called isokinetic exercise, e v e nwhen conducted for short periods oft i m e, can cause muscle enzymes to shiftto glycolysis and increase the productionof actin and myosin in muscle.6 - 9 Th i sallows the muscle to build strength andincrease its ability to work with low-oxy-gen tension.1 0 High-intensity resistanceexercise is more effective than low-inten-sity resistance exercise to build isometricstrength and increase the cross-sectionalarea of muscle even when exercise isonly accomplished for as little as 2w e e k s.1 1 While a single protocol is effec-t i v e, multiple protocols are more effec-tive in building muscle strength.1 2

The side benefit of resistance train-ing is in the ability to prevent injury.13 Itis also effective for patients with chronicheart failure in reducing some symp-toms.14 Imbalances in upper body

strength around the rotator cuff, whichcan cause injury and pain, are easilyreduced with resistance exercise.15

Proper strength training in the uppercore muscles, such as the back muscles,can also be effective as an alternative tosurgery in reducing back pain as peopleage.16 Upper body conditioning is alsoimportant in the treatment of reducedmobility at the shoulder17 and prevent-ing upper body osteoporosis.18 Thus, forwomen, there are positive benefits intotal health of the upper body caused byphysical activity.19 Upper body exercisehas been considered good at reducingobesity.20 More importantly, it has beenshown to reduce the risk of breast can-cer.21-24 Upper body exercise canimprove dynamic stability.25 It is usefuleven after mastectomy and breast recon-struction.26 Thus, weight-bearing pro-grams not only reduce the decline inmuscle strength27 but also have signifi-cant medical benefits. Such cosmeticbenefits of physical training can alsohave a dramatic effect on the well beingof adults and reduce depression.28

One significant problem in womenthat is often overlooked is that as agingprogresses, muscle weakness in the chestcauses the breasts to sag. This in turncan create a lever arm that causes backand neck muscle strain and soreness.This has been a major problem inwomen. Rather than simply examiningstrength and endurance with exercise,the present investigation targeted anincrease in chest firmness, musclestrength, girth, and body contours in theupper body in women before and after a1-month upper body exercise program.

SUBJECTSThere were two groups of subjects. Onegroup was composed of 32 women whoserved as controls. The other group, theexercise group, was made up of 29women in the age range of 22 to 48years old. All subjects were free of car-



diovascular disease and orthopedicinjuries to the shoulders that would pre-vent them from participating in an exer-cise program. The subjects wererandomly assigned to the control or theactive group. The total number of sub-jects was sufficient to provide reliableresults by statistical power analysis. Allexperiment procedures were approvedby the Human Review Committee atAzusa Pacific University and all subjectssigned a statement of informed consentshowing their agreement to participatein these studies. Table 1 shows the gen-eral characteristics of the subjects.

METHODSIsometric StrengthIsometric strength was measured on amodified exercise device consisting of a

tube 85 cm long and 4 cm in diameterwith strain gauges mounted in the center(Figure 1). The tube was held at chestlevel with one end in each hand, andforce was measured during horizontaladduction and abduction of the shoul-ders. The shoulders were flexed to 90ºduring all measurements. Strength wasmeasured on two occasions as 3-secondmaximum efforts with 1 minute betweencontractions. The average of the two wasused for the maximum strength.

Measurement of Muscle ThicknessMuscle thickness was measured with aTitan two-dimensional ultrasound sys-tem manufactured by Sonosite, Inc(Bothel, WA). The device provided aweak ultrasound signal at a frequency of10 million Hz. The ultrasound signal

Table 1. General Characteristics of Subjects (Group means)

Age (y) Height (cm) Weight (kg)Subjects 28.7 ± 8 163.3 ± 7.3 66.1 ±11.1Controls 27.5 ± 7.2 165.8 ± 9.1 69.26 ± 11.2

Figure 1. Upper body exercises modified for measuring strength.


Vol. 5, No. 4, 2005 • The Journal of Applied Research556

reflected from the muscles below theprobe created a two-dimensional pictureto measure the thickness of muscle. Atypical picture is shown in Figure 2. Theprobe was placed at an angle of 90o

with respect to the skin and used tomeasure the muscle thickness of thepectoralis and rhomboid muscles at thesame location as the chest wall firmnessmeasurements as described in the nextsection. For the rhomboid muscles, thearms were folded under the chin toplace the muscle in a good anatomicalposition for measurement.

Firmness of MusclesTo analyze the resting tone of muscles inthe chest and upper back, a tensionome-ter was used. The tensionometer consist-ed of a load cell, which was linear withan accuracy of ± 0.1% in a range of ± 5kg (Omegadyne Corp., Stanford, CTmodel lc-23-205). The output of the loadcell was amplified with a strain gageamplifier with a gain of 5000. This out-put was then filtered to allow band passfrom DC to 20 Hz. The analog outputwas digitized with a 16-bit A/D convert-er by a Biopac MP100 system (BiopacInc., Goleta, CA). The digitized datawere then calibrated and analyzed at alater time. The load cell was connectedto a flat post of 1 cm in length. The postwas then extended through 3 differentpieces of plexiglass that laid on the sur-

face of the skin (Figure 3). This allowedthe tensionometer to depress the skin by2.5, 4.6, and 8.0 mm below the load cell.With these three depths, a graph wascalculated for each subject showing therelationship between pressure and depthover each underlying muscle, with themuscle relaxed.

Exercise DeviceThe exercise device consisted of a pole4.0 cm in diameter and 85 cm long. Thedevice was manufactured by Savvier LP(Carlsbad, CA) and called theBustmaster. The opposite ends of thepole had compression fittings consistingof O-rings such that by compressing theends of the pole, air pressure was devel-oped in the center. Since compressed airwould not allow much movement at theopposite ends of the pole, a pressurerelease valve was in the center of thepole. When the pole was compressed, byregulating the airflow, resistance wasregulated for compression and extensionof the pole (providing bidirectionalresistance). In practice, to push theopposite ends of the pole completelytogether took approximately 3 secondswith 3 seconds to extend the pole.Compressed, the pole was 52 cm long.

GirthGirth was measured by a tensionometerapplying 3 g of tension around the chest.Girth was measured just under the axillaand at 2, 4, and 6 cm below the axilla.

Photographic Measurements of BodyThicknessTo see the contour of the upper body, aphotograph of the frontal, back, andsagittal view of each subject was taken.A grid was projected from a photo-graphic projector with spacing of 0.5 cmbetween the grid lines. The lines werered on a black background and thelights were turned off. Pictures werethen captured. The camera was at a set

Figure 2. Typical ultrasound picture.



distance from the subject and a set lenswas used. A calibration was performedeach day with a measuring scale thatwas flat and could be rotated horizontal-ly and vertically by 22.5˚ and 45˚ to cali-brate perspective.

Compliance and ExerciseCompliance was measured each day byan exercise log. Subjects also logged theworkload used in the machine. Theworkload could be set to 6 differentstages and subjects were encouraged toincrease the workload as they could tol-erate an increase during training.

PROCEDURESAll measurements were taken by techni-cians that were blinded, ie, the techni-cians did not know which subjects werein each group, thus providing a single-blinded, randomized study design.Baseline strength, girth, tissue density,and digital photo measurements of thecontrol subjects were made on two dif-

ferent occasions as a measure of therepeatability of the measurements (noexercise was performed between themeasurements). In the exercise group,after the same measurements, subjectsexercised for 1 month. They exercised 5times per week, 5 minutes per day for aperiod of 1 month. Control measure-ments involved measurement of musclethickness over the pectoralis musclesand the rhomboids bilaterally. For thepectoralis muscles, measurements weremade in the second rib interspace halfway between the sternum and the mid-clavicular line bilaterally. With the rhom-boid muscles, measurements were made3 cm above the inferior angle midway tothe spinal column bilaterally. Musclefirmness was measured at the same loca-tions, at three depths so that a graphcould be plotted relating pressure versusdepth at each of the four locations.Digital photographs were also taken asdescribed under the Methods section toestablish thickness of the chest and

Figure 3. Muscle firmness measuring device.

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anatomical position of the chest andback muscles. Girth measurements werealso made as described under methods,and muscle strength was also tested.

Two series of exercises were accom-plished during the month that werecalled sequences A and B. These werealternated daily (Figure 4). Each seriesrequired approximately 5 minutes toperform. For exercise sequence A, fivedifferent exercises were accomplishedwith 20 contractions (flexion/extensionor horizontal abduction/adduction) ofeach exercise each day. The first exerciseinvolved holding one arm above theother with the arms extended and theelbows locked. The shoulder muscleswere then flexed and extended againstthe exercise device (Figure 4). In thesecond exercise in sequence A, the exer-cise was repeated, but with the armsreversed. In the third exercise insequence A, the arms were extended,and the shoulders were at an angle of90o. The shoulders were then horizontal-ly adducted and abducted. In the fourthexercise in sequence A, the elbows werekept extended and the shoulders flexedsuch that the arms were at an angle of130o with reference to the long axis ofthe body. The shoulders were then hori-

zontally adducted and abducted for theexercise. Finally, for the fifth exercise inthis series, the arms were lowered to anangle of 45o with the elbows extendedand the shoulders were horizontallyadducted and abducted.

Exercise sequence B also involvedfive exercises. In the first exercise, t h eelbows were extended with the armsextended such that one arm was 10o l o w e rthan the other arm. One arm, in effectt h e n , was at an angle of 70o and the otherat 120o at the shoulder and the exercisemachine was compressed and extended.In the second exercise, the arms werereversed and the exercise was repeated.In the third exercise in the series, t h eelbows were bent at an angle of 90o a n dthe shoulders also bent at 90o with refer-ence to the body. Horizontal adductionand abduction were then accomplished atthe shoulder. In the fourth exercise in thes e r i e s, the elbows were extended, but theright arm was kept at the side with theleft arm extending far enough forward tohold the exercise machine, and themachine was compressed and extended.The last exercise involved the same exer-cise but with reversal of the arms. Th eexercise load was increased each week toachieve training.

Figure 4. Subject during exercise.



RESULTSFor the control subjects, there was nosignificant difference in the pre and postmeasurements of strength, girth, muscle

thickness, or chest dimensions by digitalanalysis. For example, Figure 5 showsthe graphic relationship between depthand pressure for the pectoralis major

Figure 5. Firmness was measured as depression depth of the pectoralis major (A) and rhomboidmuscles (B) versus tension to depress the chest or back wall. Data are shown before and afterthe control period.



and rhomboid muscles. Data for thegroup ± SD is shown before and afterthe control period. There was no signifi-cant difference between the data beforeand after the control period (P>0.05).The same was true for the girth meas-urements for the upper part of the body.As shown in Figure 6, while there weredifferences in the girth measurementsbefore and after the control period, theywere not significant (P>0.05). Anotherexample is the digital body curvaturemeasurements (Figure 7). The measure-ments went from cephalic to caudal, andthe body contours are shown. There wasno significant difference before andafter the control period (P>0.05).Strength was not significantly different(P>0.05).

For the experimental group, thecompliance of the subjects is shown inFigure 8. Compliance was on a 5-pointscale. The subjects were instructed towork out 5 days per week. A score of 3would indicate that they worked out 3days in that week. Some subjects

worked out 6 days per week and, there-fore, their compliance score was above5. As can be seen in this figure, compli-ance was 5.24 for the first week, 4.88 forthe second week, 5.0 for the third week,and 5.12 for the fourth week. This gavean average compliance of 5.06.

Subjects were also instructed toincrease the workload each week as theycould tolerate the increased workload.The increase in the workload is rated in1 to 6 since the device allowed work tobe increased in 6 steps, with 6 being theheaviest. Figure 8B shows the increasein workload that, after the 4 weeks, hadincreased by 251%.

Given the high compliance and theincrease in load, it was not surprisingthat strength increased for abductionand adduction. When comparing thestrength for shoulder horizontal abduc-tion and adduction before and after the1-month training period, subjectsshowed a significant increase in musclestrength in the 1-month training period(P<0.01), with an average increase in

Figure 6. Girth measured before and after the control period.



strength from 23.0 ± 6.3 to 29.1 ± 8.5 kgfor horizontal abduction and 24.3 ± 9.1to 31.4 ± 9.4 kg for horizontal adduction(Figure 9A).

By using two-dimensional ultrasound,the muscle thickness of the pectoralismajor and rhomboid muscles were meas-ured (Figure 9B). The average musclethickness increased from 0.87 to 1.12 cmfor the average of the left and right sideof the body for the pectoralis major mus-cles and, while the increase was smallerfor the rhomboid muscles, for both groupsthe increase was significant (P< 0 . 0 1 ) .

This increase in muscle thicknessand strength increased the firmness ofthe chest wall. Although subjects werefully resting during the measurements,when relating displacement distance totension with a tensionometer describedunder the Methods section, the curveshowed a significant increase. As shownin Figure 10A, for the pectoralis majormuscles bilaterally on both sides of thechest, and Figure 10B for the rhomboids,there was a nonlinear increase in forceassociated with depression of the chest

wall. After 1 month of training, muscletone increased at the three differentmeasuring depths as shown in each ofthe respective panels of this figure in theupper lines. These increases in resistanceto depression at the three differentmeasuring distances were all significant(P<0.01). For the greatest compressionof the chest wall, firmness increased by32% for the pectoralis major musclesand 24.5% for the rhomboid muscles.

Obviously, if muscle thicknessincreases, so should the girth of thebody. The changes in girth are shown inFigure 11. As can be seen in this figure,there was an increase in girth of thechest by 1.95 ± 0.8 cm. The same wastrue for the distal measurements (Figure12). The average increase in girth fromthe digitized picture measurements was11.1%. In inches, initial chest girth was36.4 (92.5 cm), increasing to 37.2 inches(94.9 cm) after training. Furthermore,firming in the upper body caused thebreast line to rise (measured from digi-tal measurements is the distance fromthe acromion to the nipple), an average

Figure 7. Digital measurement of chest size before and after control period.



of 0.45 ± 0.22 cm (Figure 13), (P<0.01).

DISCUSSIONThere is long-standing evidence thatexercise programs, even in geriatricpatients, are beneficial to increase bal-ance, strength, and reduce the incidenceof falls.29 Exercise not only increases

muscle strength, but there is evidencethat it improves the integrity of sensorynerve fibers in the skin and may con-tribute to whole body stability.30 Buteven in younger individuals, exercise canreduce the incidence of back injuries,even in athletes.31

With resistance exercise, it is not

Figure 8. Compliance of the subjects for the exercise by the week is shown in panel A com-pared to the weekly average workload for the daily workouts in panel B.



uncommon to see strength increasewithin days along with an increase inmuscle tone.2 To increase strength fur-ther, some have been tempted to useanabolic steroids.32 The nonsteroidalroute involves isokinetic exercise, a typeof exercise involving lifting weightsslowly against heavy loads.6-9 Strength

training is especially important in peoplewho get repetitive injuries. Poor upperbody strength and balance, especially inthe back and rotator cuff muscles canlead to their injuries.15 With a high inci-dence of upper back injury in women,33

upper body training is increasinglyimportant. This is made more important

Figure 9. Muscle strength of the subjects before and after the training period (A) and musclethickness by ultrasound before and after training for the pectoralis and rhomboid muscles (B).

B

Muscle Strength



in women due to higher weight of thebreast placing stress on the upper backand neck muscles.34-36 This can be trueeven in power lifters.37 When coupledwith a higher incidence of osteoporosisin the spine in women (vertebral osteo-porosis), this provides simply anotherpredisposing factor to injuries.38

In the present investigation, exercise

was only conducted for 5 minutes a daywith 5 different exercises for a group ofwomen involved in an exercise-testingprogram. The results of the experiment,however, show that even 5 minutes ofexercise a day significantly increasesupper body strength. This translated toan increase in chest firmness measure-ments, girth, and the thickness of the

Figure 10. Firmness of the chest and back shown as compression force versus depth for the pec-toralis (pecs) (A) and rhomboid muscles (B).



muscle layer above the pectoralis majorand rhomboid muscles. Since imbalancesaround the rotator cuff have commonlybeen causal to injury,1 5 this type of exer-cise should reduce injury incidence inindividuals engaging in such an exercisep r o g r a m . The wide range of motioninvolving horizontal abduction, h o r i z o n t a la d d u c t i o n , e x t e n s i o n , and flexion associat-ed with these exercises may also providetreatment for mobility at the shoulder.Mobility exercises to the shoulder havebeen shown to reduce osteoporosis.1 8Th u s, for women there are positive bene-fits of increasing mobility at the shoul-d e r1 7 and other benefits of exerciseincluding increases of muscle blood flow.F u r t h e r m o r e, exercise has been shown toreduce the risk of breast cancer.2 1 - 2 4

Another benefit of the exercise pro-gram examined here was in lifting thebreast line. One common complaint ofwomen is sagging breasts as they age.With large breasts, surgical interventionor wearing prosthetic appliances is com-mon to alleviate pain and back injury.39

In one study, Mizgala and Mackenzie39

showed that in cases of 75 bilateralbreast reductions, patients reported bet-ter posture and relief of lower back painas the result of surgical intervention andreducing the size of their breasts. In alllikelihood, strengthening the upper bodymuscles may have had a similar effect incompensating for the load of largebreasts against the upper body as seenhere. Another common complaint ofwomen is neck pain as well as back pain,and shoulder grooving.40 Exercise inter-vention was not tried in these studies tostrengthen the neck, back, and chestmuscles to compensate for the weight ofsagging breasts and thus alleviate manyof the symptoms. Christensen16 foundthat exercise can be just as effective assurgery in reducing back pain as peopleage. It would be reasonable, then, thatexercise intervention may also preventmany of the large number of surgeriesperformed on women with large breasts.

Finally, for women with smallbreasts, the increased firmness and con-touring of the chest would have goodbenefits medically in terms of stability of

Figure 11. Chest girth before and after the 1-month period at the axilla and at 2, 4, and 6 cmbelow the axilla.



the chest wall, and also psychologically,for a better outlook about theirphysique. Self-esteem becomes an

important issue for women, and upperbody exercise can dramatically improveself-esteem.28

Figure 12. Thickness of body from photographic measurements before and after a 1-month exer-cise program.

Figure 13. The change in distance from the shoulder to the breasts in the subjects before andafter the exercise training.



In summary, given the small timecommitment and effort of exercise atonly 5 minutes per day, there are goodbenefits for such a device. Compliancefor 30-minute exercise programs is poordue to the time commitment. Here, 5minutes is a time that anyone can sparebut with dramatic results in terms ofesteem and lifestyle that are a testamentto the benefit of the exercise. The resultshere show strength increased and mus-cle thickness increased, this caused girthand firmness to increase and the con-tours of the body on photo image toincrease as well.

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