🏋🏼Sports Medicine Unit 3 – Exercise physiology

Key Concepts in Exercise Physiology

• Exercise physiology studies how the body responds and adapts to physical activity and exercise
• Focuses on the physiological mechanisms that enable the body to perform work and maintain homeostasis during exercise
• Examines the acute responses and chronic adaptations of various body systems (cardiovascular, respiratory, muscular, and endocrine) to exercise
• Investigates the role of energy systems (ATP-PC, glycolytic, and oxidative) in fueling different types and durations of exercise
• Explores the concept of specificity, which suggests that physiological adaptations are specific to the type of training performed
• Applies knowledge to optimize athletic performance, prevent injuries, and promote health through exercise prescription
• Considers individual differences in response to exercise, such as age, gender, fitness level, and genetic factors

Energy Systems and Metabolism

• Three primary energy systems provide ATP for muscle contraction during exercise: ATP-PC system, glycolytic system, and oxidative system
  • ATP-PC system utilizes stored ATP and phosphocreatine for high-intensity, short-duration activities (weightlifting, sprinting)
  • Glycolytic system breaks down glucose or glycogen to produce ATP for moderate to high-intensity activities lasting up to 2-3 minutes (400m run)
  • Oxidative system uses carbohydrates, fats, and proteins to generate ATP for low to moderate-intensity, long-duration activities (marathon running)
• Energy systems work together and contribute to varying degrees depending on the intensity and duration of the activity
• Metabolism refers to the chemical processes that convert food into energy for cellular functions and physical activity
• Aerobic metabolism occurs in the presence of oxygen and is the primary energy source for low to moderate-intensity exercise
• Anaerobic metabolism does not require oxygen and is the primary energy source for high-intensity, short-duration exercise
• Excess post-exercise oxygen consumption (EPOC) represents the increased oxygen uptake after exercise to restore homeostasis and replenish energy stores

Cardiovascular Adaptations to Exercise

• Regular exercise leads to beneficial adaptations in the cardiovascular system, enhancing its efficiency and capacity to deliver oxygen and nutrients to working muscles
• Cardiac output, the volume of blood pumped by the heart per minute, increases during exercise due to an increase in heart rate and stroke volume
• Stroke volume, the amount of blood ejected from the left ventricle with each heartbeat, increases as a result of exercise-induced cardiac hypertrophy and improved contractility
• Capillarization, the growth of new capillaries in skeletal muscle, enhances oxygen and nutrient delivery to working muscles and improves waste removal
• Blood volume expands with regular exercise, allowing for greater oxygen-carrying capacity and improved thermoregulation
• Endothelial function improves, leading to better vasodilation and blood flow regulation during exercise
• Resting heart rate decreases as the heart becomes more efficient, allowing for a greater reserve capacity during exercise

Respiratory Responses During Exercise

• The respiratory system plays a crucial role in delivering oxygen to working muscles and removing carbon dioxide during exercise
• Ventilation, the volume of air inhaled and exhaled per minute, increases linearly with exercise intensity to meet the increased oxygen demand
• Tidal volume, the amount of air inhaled or exhaled with each breath, increases during exercise to enhance gas exchange
• Respiratory rate, the number of breaths taken per minute, increases to accommodate the higher ventilatory demands of exercise
• Oxygen uptake ($\dot{V}O_2$) represents the volume of oxygen consumed by the body per minute and is a key indicator of aerobic fitness
• $\dot{V}O_2$ max, the maximum volume of oxygen that can be consumed per minute, is a measure of an individual's maximal aerobic capacity
• Respiratory muscles, such as the diaphragm and intercostals, adapt to regular exercise, becoming stronger and more efficient
• Ventilatory threshold, the point at which ventilation increases disproportionately to oxygen uptake, is an important marker for prescribing exercise intensity

Muscular Function and Adaptation

• Skeletal muscle is a highly adaptable tissue that responds to the specific demands placed upon it during exercise
• Muscle fibers are classified into two main types: slow-twitch (Type I) and fast-twitch (Type II)
  • Slow-twitch fibers are fatigue-resistant and well-suited for endurance activities
  • Fast-twitch fibers generate high force but fatigue quickly, making them ideal for explosive, high-intensity activities
• Muscle hypertrophy, the increase in muscle size, occurs in response to resistance training due to an increase in the size of individual muscle fibers
• Muscle strength, the maximum force a muscle can generate, improves with resistance training through neural adaptations and hypertrophy
• Muscle endurance, the ability to perform repeated contractions over an extended period, enhances with training that emphasizes high repetitions and short rest intervals
• Delayed onset muscle soreness (DOMS) is a common consequence of unaccustomed or high-intensity exercise, resulting from micro-tears in muscle fibers
• Muscle fiber type composition is largely determined by genetics but can be influenced to some extent by specific training

Thermoregulation and Exercise

• Thermoregulation is the body's ability to maintain a relatively constant core temperature despite changes in environmental conditions and physical activity
• Exercise generates significant heat as a byproduct of muscle contraction, which must be dissipated to prevent overheating
• Sweating is the primary mechanism for heat dissipation during exercise, allowing evaporation to cool the skin and blood
• Cutaneous vasodilation increases blood flow to the skin, facilitating heat transfer from the core to the environment
• Dehydration can impair thermoregulation by reducing blood volume and sweat production, leading to increased core temperature and decreased performance
• Heat acclimatization, the physiological adaptations that occur with repeated exposure to hot environments, improves the body's ability to regulate temperature during exercise
• Clothing and equipment choices can influence thermoregulation by affecting heat dissipation and sweat evaporation
• Environmental factors, such as ambient temperature, humidity, and wind speed, play a significant role in thermoregulation during exercise

Exercise Testing and Prescription

• Exercise testing assesses an individual's cardiovascular fitness, muscular strength and endurance, flexibility, and body composition
• Graded exercise testing (GXT) is a common method for evaluating cardiovascular function and aerobic capacity, typically performed on a treadmill or cycle ergometer
• $\dot{V}O_2$ max can be directly measured during a GXT or estimated using submaximal tests, such as the Astrand-Rhyming cycle ergometer test or the Cooper 12-minute run test
• One-repetition maximum (1RM) tests assess an individual's muscular strength for specific exercises
• Flexibility can be evaluated using various methods, such as the sit-and-reach test or goniometry
• Body composition can be assessed using techniques like skinfold measurements, bioelectrical impedance, or hydrostatic weighing
• Exercise prescription involves designing a personalized exercise program based on an individual's fitness level, goals, and health status
• The FITT principle (Frequency, Intensity, Time, and Type) is used to guide exercise prescription and progression
• Target heart rate zones are often used to prescribe and monitor exercise intensity based on a percentage of an individual's maximum heart rate or heart rate reserve

Practical Applications in Sports Medicine

• Sports medicine professionals apply exercise physiology principles to prevent, diagnose, and treat sports-related injuries and illnesses
• Pre-participation physical examinations (PPEs) screen athletes for potential health risks and guide appropriate exercise recommendations
• Injury prevention programs focus on improving strength, flexibility, and proprioception to reduce the risk of common sports injuries
• Rehabilitation protocols incorporate exercise principles to facilitate recovery and return to play following an injury
• Athlete monitoring using heart rate variability, GPS tracking, and subjective measures helps optimize training loads and prevent overtraining
• Nutritional strategies, such as carbohydrate loading and hydration management, are used to enhance athletic performance and recovery
• Environmental considerations, like heat stress and altitude training, are addressed to ensure athlete safety and performance
• Doping control and education programs aim to maintain fair play and protect athlete health by preventing the use of banned performance-enhancing substances