Principles in Exercise Physiology

Summary

This lecture delves into the foundational principles of exercise science, essential for understanding how the body adapts to physical stress during exercise. It covers homeostasis, the body's drive to maintain a stable internal environment, and how it responds to disruptions like high-altitude exercise. The lecture also explores the overload principle, explaining how consistent exercise leads to long-term physiological adaptations, such as increased mitochondrial density in muscles. The specificity principle highlights that only stressed body parts or systems adapt, while reversibility illustrates that inactivity leads to a loss of these adaptations. Lastly, the individuality principle acknowledges the genetic influence on the variability of training responses among individuals.

Takeaways

• 🌡️ Homeostasis is the body's tendency to maintain a stable internal environment for cells by regulating variables like pH, oxygen tension, blood glucose, and body temperature.
• 🏋️‍♂️ Exercise disrupts homeostasis, prompting the body to make adjustments in physiological and biochemical systems to restore balance.
• 🚀 The cardiovascular system responds to exercise by increasing heart rate, stroke volume, and blood flow to working muscles to meet increased oxygen and nutrient demands.
• 💪 The overload principle states that habitually stressing a system leads to adaptations, such as increased mitochondrial number and oxidative capacity in skeletal muscle with endurance training.
• 🔍 The specificity principle indicates that only the systems or body parts repeatedly stressed will adapt, meaning targeted training is necessary for specific improvements.
• ↔️ The reversibility principle suggests that without continued training, adaptations made during exercise will return to baseline levels, illustrating the 'use it or lose it' concept.
• 👤 The principle of individuality highlights that genetic factors influence the variability in training adaptations among individuals.
• 🧬 Genetic differences mean that even with the same training stimulus, individuals may show varying degrees of adaptation in performance and physiological markers.
• 🧠 The nervous and endocrine systems play a crucial role in regulating the body's response to exercise, including heart rate, blood vessel dilation, and blood redistribution.
• 🌡️ Thermoregulatory processes are activated during exercise to manage increased body temperature, another necessary adjustment the body makes to maintain homeostasis.

Q & A

What is the principle of homeostasis and why is it important in exercise science?

Homeostasis is the body's tendency to maintain a stable internal environment for cells by narrowly regulating critical variables such as pH, oxygen tension, blood glucose concentration, and body temperature. It is important in exercise science because any disruption to optimal homeostatic conditions during exercise elicits multiple regulatory responses by the body to bring disrupted variables back to normal levels.

How does the body respond to a disruption in homeostasis during high-altitude ascent?

During high-altitude ascent, due to the low oxygen pressure in the inspired air, oxygen levels in the blood drop below desired levels. This disruption in homeostasis triggers adjustments by the nervous, endocrine, cardiovascular, and respiratory systems to compensate for the decreased oxygen availability.

What are some of the necessary adjustments the body must make in response to the stress of a single bout of exercise?

In response to exercise stress, the body must regulate blood pH to prevent it from becoming too acidic, maintain blood oxygen and glucose levels to prevent them from falling below normal, and activate thermoregulatory processes to manage increased body temperature.

How does the cardiovascular system adjust to ensure proper oxygen and nutrient delivery during exercise?

The cardiovascular system adjusts by increasing the heart's pumping force, dilating blood vessels to the muscles to enhance local blood flow, and redirecting blood flow from less critical tissues to the working muscles. These adjustments are regulated by the nervous and endocrine systems, which increase heart rate, stroke volume, and cardiac output.

What is the overload principle in the context of exercise training?

The overload principle states that if a system is habitually subjected to a stress or load that exceeds its normal functional limit, it will respond and adapt. In exercise, this means that engaging in physical activity imposes stress on the body, leading to acute responses, and if this stress is repeated over time, the body will make long-term adaptations.

Can you provide an example of a long-term adaptation resulting from the overload principle?

An example of a long-term adaptation from the overload principle is an increase in mitochondrial number and oxidative capacity in skeletal muscle in response to weeks and months of endurance training. This adaptation is due to the chronic activation of signals responsible for mitochondrial biogenesis.

What does the specificity principle imply for training adaptations?

The specificity principle implies that only the system or body part repeatedly stressed will adapt to chronic overload. For instance, chest muscles will improve in strength from bench presses, while other muscle groups not involved will show no training adaptations.

How does the reversibility principle relate to exercise training and adaptations?

The reversibility principle suggests that if the stimulus for regular training is removed, any adaptations made during training will eventually return to baseline or pre-training levels. This is often seen when individuals stop training due to illness or injury, and their previously gained fitness levels decline.

What is the principle of individuality in the context of exercise training adaptations?

The principle of individuality states that while the physiological responses to a particular stimulus are largely predictable, the precise responses and adaptations will vary among individuals based on genetic characteristics. This means that even if two individuals are of the same age, sex, and fitness level, their training adaptations may differ in magnitude.

How does the principle of reversibility demonstrate the 'use it or lose it' concept in exercise science?

The reversibility principle demonstrates the 'use it or lose it' concept by showing that once regular exercise training is stopped, the body will lose previously gained adaptations. For example, after eight weeks of endurance training, markers of mitochondrial oxidative capacity and maximal oxygen uptake increase, but if training stops, these markers return to pre-training levels.