Introductory physiology and background

Exercise physiology: study of how our body’s systems response to exercise acutely and chronically

Physical Activity vs. Exercise

• Physical Activity:

  • Encompasses all movements performed in daily living, including routine tasks and leisure activities.

• Exercise:

  • A planned, structured, and repetitive form of physical activity aimed specifically at improving or maintaining fitness and performance levels.

Guidelines for Physical Activity

• ACSM Guidelines:

  • Recommend at least 30 minutes of moderate-intensity physical activity three times a week for the last three months.

• CDC & US Department of Health Recommendations:

  • 150 to 300 minutes per week of moderate-intensity aerobic activity along with two days per week of muscle-strengthening activities that involve all major muscle groups (Physical Activity Guidelines for Americans, 2nd edition).

MOVE YOUR WAY

• Moderate-Intensity Aerobic Activity:

  • Activities that increase heart rate; any movement that accelerates the heart rate is included.

• Muscle-Strengthening Activity:

  • Activities that require greater effort from muscles than usual.

• Frequency Recommendations:

  • At least 150 minutes per week of moderate-intensity activities OR 75 minutes a week of vigorous-intensity activities with a mixture preferred.

• Starting Small:

  • Encourages even minimal physical activity (e.g., 5 minutes) for health benefits.

• Suggestions for Activities:

  • Walking, running, dancing, playing sports, as personal choices.

Sedentary Behavior and Activity Trends

• Statistics on Sedentary Individuals:

  • A significant portion of the population is sedentary during leisure time, with 35% reported inactivity.

• 2023 Data Highlights:

  • Only 28% of Americans meet physical activity guidelines; regions like Louisiana and Kentucky show low activity levels.

Key Guidelines for Adults

• General Recommendations:

  • Adults should engage in more movement and less sedentary behavior.

  • Some activity is better than none; engaging in moderate-vigorous activity yields health benefits.

  • For substantial benefits:

  • 150 to 300 minutes of moderate-intensity or 75 to 150 minutes of vigorous-intensity activity weekly is advised.

  • Muscle-strengthening activities should occur on two or more days per week for additional health advantages.

Sedentary Time vs. Activity

• Morris et al. (1953) Study:

  • Examined London bus workers’ heart disease risk, finding that conductors (more active roles) had significantly reduced heart attack and CV disease mortality compared to drivers.

Inactivity Physiology

• Focus on Inactivity:

  • Highlights the importance of understanding inactivity physiology and its health implications.

  • Encourages investigation of the question: Does exercise matter?

Health Benefits of Exercise

• Exercise Benefits:

  • Exercise (both aerobic and resistance) offers extensive health benefits beyond preventing a sedentary lifestyle.

  • Essential for improved muscle, bone, joint health, reduced mortality, and lower incidence of chronic diseases (CV disease, cancer, diabetes).

  • Also associated with improved mental health.

Clinical Applications

• Importance of Exercise in Disease States:

  • Exercise provides powerful benefits in aging, specifically for populations with cardiovascular disease, diabetes, obesity, and other conditions.

  • Exercise can serve a preventative role as well as a rehabilitative one.

Specific Case Studies: Exercise Physiology

• Dilated Cardiomyopathy & Ischaemic Hearts:

  • Illustrates how exercise training can enhance stroke volume (SV) and cardiac output despite existing conditions like cardiac fibrosis.

Exercise Physiology in Clinical Settings

• Significance of Understanding Responses:

  • Familiarity with acute and chronic responses to exercise is crucial when creating tailored exercise interventions for clinical populations.

  • Helps in identifying minimally effective doses of exercise, such as recommendations for diabetes management.

Recreational and Athletic Applications

• Human Performance Limitations:

  • Focuses on how to maximize athletic performance across various domains, including sprinting, distance running, and skills acquisition.

Limits of Human Performance: The 2-Hour Marathon

• Breaking 2-Hour Marathon Initiative:

  • Eliud Kipchoge's notable achievement of running 2:00:25, followed by a second attempt at 1:59:40, highlighting extraordinary athletic feats and physiological limits.

  • Discussion on the historical significance equivalent to Roger Bannister breaking the 4-minute mile.

Understanding Sex/Gender Disparities in Running

• Cultural Barriers:

  • Focus on the late participation of women in marathons, highlighted by Kathrine Switzer's disguise in the 1967 Boston Marathon.

Sprint/Jump Performance

• Limits of Physiological Adaptations:

  • Examines elite sprinting performance illustrated by Usain Bolt and the physiological constraints involved.

  • Discussion includes contraction/relaxation cycles per second, and comparative analysis with animal capabilities.

Economic Value of Sports Medicine

• Market Valuations:

  • 2024 projections: US Sports Medicine market at $2.7 billion, and sports nutrition supplement industry valued at $5.67 billion.

  • Highlights significant investments in technology and performance optimization within sports.

Basic Physiology Recap

• Terms for Review:

  • Homeostasis, physiological stress, nervous system divisions (central/peripheral), receptors and hormones, and mechanisms of metabolism.

• Homeostasis Definition:

  • The physiological process that maintains a stable internal environment amidst external changes.

Physiological Stress

• must regulate or compensate through complex neural signaling which is mediated by the release of neurotransmitters (messengers between central and peripheral neurons) and hormones (regulatory substances that stimulate specific actions from cells or body tissues)

Regulation Types

• Thermoregulation:

  • Body temperature regulation mainly via skin and blood flow adjustments.

• Osmoregulation:

  • The management of water and mineral levels, primarily by kidneys.

• Hemodynamic Regulation:

  • Adjustments to heart rate, blood pressure, and blood flow to satisfy oxygen demands and prevent tissue damage.

• Chemical Regulation:

  • Regulation of body chemicals, principally managed by the liver.

Physiological Stress Responses Process

• Response Steps:

  1. Detect stress/change.

  2. Assess deviations from the typical setpoint.

  3. Send signals to effectors (cells, organs).

  4. Elicit responses to restore homeostasis.

Compensation Mechanisms

• Response Strategies:

  • Feedback loops,

    • primarily negative,

      • that initiate reflexive changes to counter stress.

        • body is cold → heat generating reflexes

        • eating a large meal, blood glucose spikes → insulin is released

  • another example of positive feedback in blood clotting.

Feedback Loop Example

• Temperature Regulation:

  • Negative feedback loop involving sweat glands and the body's temperature sensors.

• Blood Glucose Regulation:

  • Mechanism for maintaining optimal blood glucose levels through insulin and glucagon release.

Adaptations to Chronic Physiological Stress

• Homeostatic Adjustments:

  • Exposure to stressors can redefine homeostatic setpoints leading to chronic adaptations.

Exercise as Stress

• Responses to Exercise:

  • Exercise induces physiological responses such as increased heart rate and sweat production, resulting from altered homeostasis.

Exercise Responses

• Physiological Demand Adjustments:

  • Responses involve feedback from receptors (temperature, pH, glucose levels, etc.), integrating data in the brain and prompting hormonal changes (e.g., epinephrine).

Course Consideration

• Focus Areas:

  • For every physiological system covered (metabolic, neuromuscular, cardiovascular, respiratory), understand both acute compensation mechanisms during exercise and chronic systemic adaptations.