Physiological Adaptations in Response to Training
- Resting heart rate
- Stroke volume and cardiac output
- Oxygen uptake and lung capacity
- Hemoglobin level
- Muscle hypertrophy
- effect on fast/slow twitch muscle fibers
Resting Heart Rate
- Refers to the number of contractions the heart makes in 1 minute while the body is at rest after a workout rep.
- Trained athletes have a lower resting heart rate than those without proper training due to higher efficiency of the cardiovascular system.
- Athletes with a lower resting heart rate do not get exhausted easily, because of sufficient oxygen supply in the cells.
- Allows athletes to recover even in small resting periods.
Stroke Volume and Cardiac Output
- Stroke volume refers to the amount of blood the heart pumps/contraction.
- Cardiac output refers to the total amount of blood pumped/minute.
Cardiac output = heart rate x stroke volume
- Trained athletes have a cardiac output of 20-25L/minute facilitating in oxygen transport at a higher rate.
Oxygen Uptake and Lung Capacity
- The amount of O2 an individual’s body uses in 1 minute is called oxygen uptake.
- For an individual, their maximum body intake of oxygen is denoted by VO2 max; which is measured using the 12 minute run and beep test.
- VO2 max is representative of an athlete’s cardiorespiratory endurance.
- VO2 max will increase if the number of oxidative enzymes, capillaries and mitochondria increase.
- Lung capacity refers to the amount of oxygen that can be inhaled and exhaled by an individual.
- It relatively remains unchanged during training.
- Over time with training the lung capacity might increase due to increase in capillary density and number of mitochondria.
- Hemoglobin is the oxygen-transporting protein in our blood.
- With anaerobic training, athletes are capable of producing more hemoglobin (20% increase) which then helps in transporting oxygen at higher levels.
- Increased hemoglobin levels reduces the possibilities of early fatigue onset in athletes.
- Increase in the size of muscles.
- Muscle fibers grow from stimuli obtained from physical activity during training programs.
- Muscle atrophy occurs if training intensity is lowered or training sessions are skipped.
- Increase in muscle size increases the strength, endurance and power of muscles.
Effect on Fast/Slow Twitch Muscle Fibers
- For slow twitch, contraction of red fibers occurs for prolonged time periods.
- Endurance activities like marathons, swimming, cycling demand slow twitch muscle fibers.
- Slow twitch fibers also make muscles resistant to fatigue.
- Fast twitch (white) muscle fibers quickly reach the tension threshold, and contract quickly.
- Fast twitch muscle fibers last for shorter time periods and are susceptible to fatigue.
- Fast twitch fibers enhance explosive movements that require a combination of power and strength (example: weight lifting).
- Both aerobic and anaerobic activities are allowed by fast twitch fibers.