Understanding Factors Affecting Metabolism and Exercise Physiology
Factors Modifying Resting Metabolic Rate (RMR)
Factors that modify RMR include body surface area, age, sex, hormones, weather, temperature, and stress.
Energy Costs During Exercise
The measurement of VO2 is very accurate for assessing metabolism at rest and during exercise.
Aerobic Energy Cost
VO2 can be measured in relative or absolute terms. Increasing energy needs cause the metabolism to increase in direct proportion to the work performed. Once a maximum level is reached, aerobic metabolism can be maintained briefly.
Aerobic Maximum (VO2 Max)
Normal VO2 max values are typically 38-42 for women and 44-50 for men. Elite athletes may have values of 80-85. VO2 max values depend on the muscles involved, age, sex, level of training, and genetic constitution.
VO2 Max Importance
VO2 max is an index of the functional capacity of the cardiovascular and respiratory systems and the ability of tissues to use oxygen to produce power aerobically.
Anaerobic Threshold
As exercise intensity increases, blood lactate levels also increase. There is a level of intensity at which lactate accumulates significantly in the blood; this is called the anaerobic threshold and is accompanied by changes in respiratory gases. This point represents the maximum intensity at which one can exercise without significant lactate accumulation.
Anaerobic Threshold and Lactate Levels
The anaerobic threshold corresponds to blood lactate levels of 4 millimoles and an intensity of 60-70% of VO2 max in untrained individuals. It provides information on the resistance to aerobic capacity during high-intensity physical activity over a long period without lactate accumulation.
Anaerobic Energy Costs
During very long-term efforts, VO2 can increase due to higher fat consumption, increased body temperature, dehydration, and decreased efficiency. Excessive oxygen consumption post-exercise (EPOC) can indicate a lack of efficiency, where oxygen consumption is higher than it should be.
Excess Post-Exercise Oxygen Consumption (EPOC)
For many years, it was thought that EPOC only reflected the oxygen required to recover ATP and PCr reserves, eliminate lactate, and restore muscle glycogen reserves. However, current understanding includes other factors such as elevated body temperature and catecholamine levels.
Training Principles
Top-Down Approach
If one part of the body fails, it affects the whole system.
Holistic Training
Training should aim for harmony among all physical qualities.
Principle of Specificity
Once a general fitness level is achieved, training must become specific to the activity.
Principle of Interrelationship
Physical qualities are interrelated. Training one activity may benefit, hinder, or have no effect on another, depending on the sport.
Principle of Progression
Training stimuli should progressively increase as adaptations occur. Start with low volume and gradually increase to an adequate level, then increase intensity.
Principle of Proportion
Work and rest should be proportionate to achieve the desired performance.
Principle of Individualization
Training should be adapted to each individual, even when performed in a group.
Training Variables
Key training variables include load, frequency, rest, and recuperation.
Seyle’s Law and Supercompensation
Seyle’s Law states that a physical stressor causes imbalance, and the body responds by adapting to the new situation and rebalancing. After a series of defense mechanisms, the body restores energy sources and improves beyond the initial level (supercompensation).
Recovery Phases
- Small breaks during continuous recovery.
- Rapid recovery where toxic substances are eliminated and oxygen is restored (between 30 minutes and 3 hours).
- Full recovery achieving supercompensation (24-84 hours).
Duration of Recovery
The duration of recovery depends on age, sport experience, gender, level of training, duration of effort, intensity of effort, physical and psychological state, and diet.
Stimulus and Adaptation
If a stimulus is repeated consistently without adequate rest, performance decreases. If the stimulus is repeated after too long a break, the effects of supercompensation are lost. Repeating the stimulus after adequate rest leads to effective training.
Deductions from Seyle and Schultz
- To improve physical condition, periodic training is necessary.
- Rest is as important as work.
- Fatigue and subsequent supercompensation are proportional to the work performed.
- Effort should be sufficient to improve but not excessive.
- Workload should increase over time to maintain the effectiveness of training.