Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Chapter 11

Individual Differences and Measurement of Energy Capacities


Specificity

• High O2 max in one event doesn’t ensure a high O2

max in another event.

• High Aerobic High Anaerobic Power

• High Anaerobic High Aerobic Power

VV


Generality

• High aerobic power usually indicates above-average power in related activities.


Overview of Energy-Transfer Capacity During Exercise


Anaerobic Energy Transfer: Evaluation of Immediate Energy Systems

• Power tests: used to measure brief maximal capacity

– Tests generally < 6 seconds

• Power is calculated as

Power = force × distance

time


Power Is Expressed in Watts

1 watt = 0.73756 ft-lbs · s-1

1 watt = 0.01433 kCal · min-1

1 watt = 0.0013 hp

1 watt = 6.12 kg · m · min-1


Stair Sprinting Power Tests

• Time to sprint up 6 steps, 3 at a time, is determined

Power = kg body wt × distance in meters

time in seconds



Jumping-Power Tests

• Sergeant jump test– Low correlation with scores and actual

ATP-PCr energy transfer

• Standing broad jump



Interrelationships Among Power Performance Tests

• Power is highly task specific.

• The usefulness of a test increases when it mimics sport performance.


Evaluation of Immediate Energy System: Physiologic Tests

• Physiologic biochemical measures evaluate– Size of intramuscular ATP-PCr pool– Depletion rate of ATP and PCr in all-out

short-duration exercise

– O2 deficit calculated from initial phase of exercise O2 consumption curve

– Alactic portion of recovery O2 consumption


Evaluation of the Short-Term Energy System

• After a few seconds of work, glycolysis generates increasingly more energy for ATP resynthesis.

• As the rate of glycolysis increases, lactate accumulates.

• Blood lactate levels provide the most common indicator of glycolytic activity.


Anaerobic Power Performance and Capacity Tests

• Performances that substantially activate short-term energy systems require maximum exercise for up to 3 minutes.

– Influences• Age • Skill• Gender • Motivation• Body size


Tests that Most Closely Mimic the Sport’s Performance

Are the Best!

• Some good, commonly used tests include– Katch test– Wingate test

• Both give measures of peak power and anaerobic capacity.




Gender Differences

• Males generally score better than females.• Difference in gender occur even in children and

adolescents despite corrections for lean body mass.

• Evidence suggests a biologic difference in anaerobic exercise between genders.


Maximally Accumulated O2 Deficit

• Determination of MAOD provides another indirect measure of anaerobic capacity.

• MAOD is determined using the linear exercise intensity_O2 consumption relationship.

• Data is collected from several submaximal treadmill trials.

• Correlates positively with other tests


Biologic Indicators for Anaerobic Power

• Blood lactate levels

• Glycogen depletion



Individual Differences in Anaerobic Energy-Transfer Capacity

• Factors contributing to differences include

– Previous training– Capacity to buffer acid metabolites– Motivation


Effects of Training

• Anaerobically trained individuals have– Greater lactate-generating capabilities– Greater depletion of muscle glycogen


Buffering of Acid Metabolites

• Training fails to increase alkaline reserve.

• Ingestion of sodium bicarbonate may increase buffering capacity and improve performance.


Motivation

• Individuals willing to tolerate pain or exhibit mental toughness are able to generate more lactate and experience greater glycogen depletion.


Aerobic Energy: The Long-Term Energy System

• Maximal oxygen capacity plays a large role in determining endurance performance.

• Attaining a high O2 max requires integration of pulmonary, CV, and neuromuscular function.

• O2 max is a fundamental measure of physiologic functional capacity for exercise.

V

V


Assessment of Maximal O2 Consumption

• Considerable research has been done to develop standardized tests to assess aerobic power and provide norms related to– Age– Gender– Body size– Training state


Criteria for Maximal O2 Consumption

• A leveling off in O2 consumption despite an increase in exercise intensity generally assures

O2max has been reached.

• Controversy regarding precise criteria remains.

• O2peak = highest value of oxygen consumption measured during graded test exercise

V

V


Maximal O2 Consumption Tests

• O2max is determined using exercise that activate the body’s large muscle groups– Treadmill

– Bench stepping

– Stationary cycling

• Test usually consists of graded exercise with much prodding to reach O2max or O2peak.

V V

V


Test Comparisons

• Two popular protocols are available.– Continuous– Discontinuous


Factors that Affect Max O2

Consumption• Mode of exercise

• Heredity

• State of training

• Gender

• Body size and composition

• Age


Mode of Exercise

• Influences muscle mass activated

• Treadmill usually > cycling

• Bench stepping similar to treadmill scores

• Arm cranking only ~ 70% treadmill values

• Specificity and skill are very influential in many modes.


Heredity

• Most physical fitness characteristics demonstrate high heritability.

• Research shows that up to 93% of difference in O2max is due to heredity.V


State of Training

• 5 − 20% variation in scores seen as fitness levels of individuals changed at time of testing


Gender

• Women achieve scores on average 15 − 30% lower than men.

• Differences may be due to

1. Muscle mass

2. Hemoglobin concentration

• Considerable variability exists; many women score higher than the average man.


Body Size and Composition

• Body size creates large differences.

• Common practice: Express O2 max relative to body mass

• Controversy exists about various methods of adjusting scores to normalcy for gender differences

• Adjustments made by each factor gives different results.

V


Age

• O2max declines after age 25 by ~ 1% per year.

• Age also influences O2max values in boys and girls.

V

V


Aerobic Capacity Prediction Tests

• Submaximal tests are used to– Decrease cost– Decrease time– Decrease risk


A Word of Caution about Predictions

• All prediction tests contain an error known as the standard error of estimate (SEE).

• SEE is expressed in measurement units used for prediction or as a percentage.

• Sometimes the SEE can be large.• At times, the SEE is small, and the test is

more useful.


Prediction Tests Commonly Used

• Walking tests

• Endurance runs

• Step tests


Predictions Based on Heart Rate

• Use exercise or postexercise heart rate and a standardized exercise regimen

• Apply linear relationship between heart rate and O2 consumption

• Data are gathered at several workloads.

• A line or “best fit” is extended through predicted maximum heart rate.


Assumptions Required for HR Predictions

• Linearity of HR – O2 consumption through all exercise intensities

• Similar maximum HR for all subjects• Constant economy and mechanical

efficiency throughout exercise• Limited daily variations in HR (usually 5

beats/min-1)


The Step Test

• Practical test that uses HR during recovery

• Prediction equations applied to test results estimate O2max with reasonable accuracy.V


Predictions from Nonexercise Data

• Data used– Gender– BMI– Physical activity rating (PAR)

• 0 − 10 over 6 months

– Perceived functional ability (PFA)


Predictions from Nonexercise Data

• Regression equations are then used to calculate scores.

Documents

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition