Energy System

SPS311 – Physical Conditioning

Mohd Fadzil b. Hj Kamarudin

UiTM

Essential Terminology ENERGY – Defined as the ability or capacity to

perform work. (e.g. mechanical, chemical, electromagnetic, heat, & nuclear energy).

BIOENERGETICS – The flow of energy in a biological system. Primarily with the conversion of food Large carbohydrate, protein, & fat molecules, which

contain chemical energy – into biologically usable form of energy.

Release the energy necessary to perform work, such as muscular activity.

Essential Terminology CATABOLISM – The breakdown of large

molecules into smaller molecules associated with the release of energy.

ANABOLISM – The synthesis of larger molecules from smaller molecules can be accomplish using the energy released from catabolic reactions.

ENDERGONIC REACTIONS – Require energy & include anabolic processes & the contraction of muscle.

Essential Terminology EXERGONIC REACTION – Energy releasing

reaction & are generally catabolic.

METABOLISM – The total of all: Catabolic/exergonic & anabolic/endergonic reactions in a

biological system.

ADENOSINE TRIPHOSPHATE (ATP) – Energy derived from catabolic/exergonic reactions is used to drive anabolic/endergonic reactions, through as intermediate molecule. ATP allows the transfer of energy from exergonic to

endergonic reactions. Without an adequate supply of ATP, muscular activity &

muscle growth would not be possible.

Essential Terminology ATP is composed of

AdenineNitrogen-containing base; riboseFive-carbon sugar (collectively called adenosine)3 phosphate (Pi) groups

Essential Terminology

ADENOSINE ENERGYP

iENERGY ENERGYPi Pi

The structure of an ATP molecule, showing the high-energy phosphate bonds.

ADENOSINEP

i

P

i

P

i

ADENOSINE P

i

P

i

P

i

ENERGY

ATPase

(ATP)

(ADP)

When the third phosphate on the ATP molecule is separated from adenosine by the action of ATPase, energy is released.

Biological Energy Systems 3 main energy systems

Phosphagen system (anaerobic system: absence of O2 molecule).

○ Primarily for short-term, high-intensity activities.○ E.g. resistance training, sprinting, power lifting.○ Phosphagen system cannot supply energy for

continuous, long-duration activities.○ ATP & creatine phosphate are stored in muscle in

small amounts.○ Type II (fast-twitch) muscle fibers.

Biological Energy Systems

3 main energy systemsGlycolysis system, of which there are two

types: fast glycolysis (anaerobic) & slow gylcolysis (aerobic).

Glycolysis is the breakdown of carbohydrate – either glycogen stored in the muscle or glucose delivered in the blood.

During fast glycolysis, pyruvate is converted to lactic acid, providing energy (ATP) at a fast rate compared with slow glycolysis, in which pyruvate is transported to the mitochondria for use in the oxidative system.

Biological Energy Systems3 main energy systems

The Oxidative (Aerobic) System Primarily source of ATP at rest & during low-

intensity activities & uses primarily carbohydrates & fats as substrates.

At rest approximately 70% of the ATP produced is derived from fats & 30% from carbohydrate.

During high-intensity aerobic exercise, almost 100% of the energy is derived from carbohydrate.

During prolonged, submaximal, steady state work, gradual shift from carbohydrate back to fats & protein as energy substrates.

Effect of Event Duration on Primary Energy System Used

Duration of Event Intensity of Event Primary Energy System(s)

0-6sec6-30sec

Very intenseIntense

Phosphagen Phosphagen & fast glycolysis

30sec-2min2-3min

HeavyModerate

Fast glycolysisFast glycolysis & Oxidative System

>3min Light Oxidative System

Aerobic Endurance Exercise Training

Physiological Adaptations to Aerobic Endurance Training Respiratory system

Enhanced oxygen exchange in the lungsImproved blood flow throughout the lungsDecreased submaximal respiratory rateDecreased submaximal pulmonary

ventilation

Physiological Adaptations to Aerobic Endurance Training Cardiovascular system

Increased cardiac outputIncreased blood volume, red blood cell

number, and hemoglobin concentrationEnhanced blood flow to skeletal muscleReduced submaximal heart rateImprove thermoregulation

Physiological Adaptations to Aerobic Endurance Training Musculoskeletal system

Increased mitochondrial size and densityIncreased oxidative enzyme concentrationsIncreased myoglobin concentrationIncreased capillarization in muscle Increased arteriovenous oxygen difference

Factors Related to Aerobic Endurance Performance Maximal Aerobic Power

Lactate threshold

Exercise economy

Fuel utilization

Fiber type characteristic

Maximal Aerobic Power High maximal aerobic power

(VO2max) is necessary for success in aerobic endurance events.

Aerobic endurance training programs should be designed to improve VO2max

Lactate Threshold

Lactate threshold – the speed of movement or percentage of VO2max at which a specific blood lactate concentration is observed or where blood lactate concentration begins to increase above resting levels.

Exercise economy

A measure of the energy cost of activity at a given exercise velocity.

Athletes with a high exercise economy expend less energy during exercise to maintain a given exercise velocity.E.g. during cycling, exercise economy can

be affected by body mass size, cycling velocity, and aerodynamic positioning.

Fuel utilization Prolonged aerobic endurance exercise at a high

intensity requires a large energy expenditure. At high exercise intensities (>70% VO2max), there is

greater reliance on carbohydrate than on fat as a fuel source.

However, In trained aerobic endurance athletes, the contribution to energy

production from fat at any given intensity is greater than in less-trained athletes.

Ability to use more fat as a fuel source is a result of the adaptations of the physiological system to training.

Fiber Type Characteristic

Type I muscle fibers are predominant in elite aerobic endurance athletes has been well established.

Type I fibers have a high mitochondrial density and oxidative enzyme capacity allowing for the majority of energy production to come from aerobic metabolism.

Aerobic endurance Training Program Design Variables Exercise mode

Training frequency

Exercise duration

Training intensity

Exercise mode Exercise mode refers to the specific activity performed

by the athlete:Cycling, running, swimming, rowing, and so on.

Athlete should select activities that mimic the movement pattern employed in competition as closely as possible.

The more specific the training mode is to the sport, the greater the improvement in performance.

Training Frequency Training frequency refers to the number of training sessions

conducted per day or per week.

Training sessions will depend on an interaction of exercise intensity and duration the status of the athlete the specific sport season.

Appropriate training frequency is important for the aerobic endurance athlete, as too much training may increase the risk of injury, illness, or overtraining.

Conversely, too little training will not result in positive adaptations to the various systems of the body.

Exercise Duration Exercise duration refers to the length of time

the training session is conducted.

The duration of a training session is often influenced by the exercise intensity: The longer the exercise duration, the lower the exercise

intensity.○ E.g. exercise conducted at an intensity above the maximal lactate

steady state (85% of VO2max) will have a relatively short duration(20-30 min) because the accumulation of lactate within the muscle will contribute to fatigue.

○ Conversely, exercise that is performed at a much lower intensity (70% of VO2max) may be performed for several hours before the athlete experiences fatigue.

Training Intensity Central to causing training adaptations in the body is

the interaction of training intensity and duration.

Generally - high intensity, shorter the exercise duration.

Adaptations in the body are specific to the intensity, or effort expended during a training session.

High-intensity aerobic exercise increases cardiovascular and respiratory function and allows fro improved oxygen delivery to the working muscle.

Type of Aerobic Endurance Training Programs

Training Type Frequency / week

Duration intensity

Long, slow distance (LSD)

1-2 Race distance or longer (30-120 min)

70% of VO2max

Pace / tempo 1-2 20-30 min At the lactate threshold; at or slightly above race

pace

Interval 1-2 3-5 min (with a work : rest ratios of

1:1)

Close to VO2max

Repetition 1 30-90 s(with a work : rest ratio of 1: 5

Greater than VO2max

Farklek 1 20-60 min Varies between LSD and pace/tempo training

intensities


Sample LSD Training Program for a Marathon Runner

Sunday Monday Tuesday Wednesday

Thursday

Friday Saturday

Rest day 45-minFartlek

run

60-minLSD run

45-minInterval run

60-min run at

race pace over hills

& flats

45-min repetition

run

120-minLSD run


Sample pace/Tempo Training Program for a 50-km Cyclist


Thursday

Friday Saturday

Rest day 60-min LSD ride

30-minPace / tempo

ride

45-minFartlek ride

45-min easy ride

30-min pace / tempo

ride

90-min LSD ride


Sample Interval Training Program for a 10-km Runner


Thursday

Friday Saturday

Rest day 10 reps of 0.5-

km intervals at race pace

with a 1:1 W:R

ratio

10-km easy run

45-minLSD run

5 reps of 1-km

intervals at race pace with a

1:1 W:R ratio

45-min LSD run

45-min Fartlek run on

flat course

Energy System

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