Exercise Physiology: The Science Behind a Healthy Lifestyle
Exercise is a fundamental component for maintaining human health. The positive effects of physical activity on the body are undeniable, yet the underlying science behind these effects is remarkably complex. New scientific findings, supported by the National Institutes of Health (NIH), shed light on the molecular processes triggered in the body by endurance training. It has been found that exercise not only strengthens the muscular system but also has profound effects on other organs and cells. These findings go far beyond previous knowledge and open new perspectives in movement research.
A remarkable study by Sanford et al. (2020), which investigated the effects of endurance training on rats, showed significant molecular changes in 18 different organs. Over a period of eight weeks, changes in gene activity, immune function, and metabolism were studied in the rats. Particularly noteworthy is that significant differences were observed between the sexes, highlighting the need for personalized training approaches in the future. Ultimately, these results could help tailor exercise recommendations to individual needs and even develop new therapeutic approaches for people who are unable to exercise due to physical limitations.
Exercise physiology, an interdisciplinary research field combining biology, medicine, and sports science, has taken on a key role in health promotion and disease prevention in recent decades. It examines the complex effects of physical activity on the human organism and has recognized that exercise not only enhances performance but also contributes to the prevention and treatment of numerous diseases. The international health motto “Exercise is Medicine,” supported by the World Health Organization (WHO), reflects this understanding.
In the field of cardiovascular health, physical activity is of central importance. To meet the increased oxygen demand of the muscles during physical exertion, the body responds by increasing heart rate and stroke volume. In the short term, these adjustments are achieved through enhanced contractility and increased filling pressures in the heart. Long-term regular training leads to structural adaptations of the heart: strength training promotes concentric hypertrophy of the heart muscle, while endurance training results in eccentric hypertrophy. These physiological adaptations improve cardiopulmonary performance and reduce the long-term risk of cardiovascular disease.
Maximal oxygen uptake (VO₂max) is considered an objective measure of cardiopulmonary fitness and is closely correlated with mortality. However, it has been shown that VO₂max is not determined solely by aerobic processes. Anaerobic metabolic pathways and individual physiological limits also play a role in determining maximal performance. Cardiovascular diseases, which remain among the leading causes of death, are significantly influenced by modifiable risk factors such as hypertension, dyslipidemia, diabetes, and physical inactivity. Physical activity significantly reduces the risk of these diseases and represents a cost-effective, non-invasive measure that also improves quality of life.
In addition to cardiovascular health, physical activity also has positive effects on the central nervous system (CNS) and cognitive performance. Imaging techniques such as MRI as well as cognitive tests, have shown that regular exercise leads to structural and functional changes in the brain. Exercise promotes sleep quality, which in turn supports neuronal regeneration, memory consolidation, and emotion regulation. This connection between movement and cognitive performance is particularly important for older adults, as physical activity significantly reduces the risk of cognitive impairment and dementia.
Furthermore, physical activity is associated with a reduction in anxiety, stress, and chronic pain. In patients with chronic pain syndromes such as fibromyalgia, exercise significantly alleviates pain intensity and associated symptoms. This is accompanied by the activation of endorphin- and opioid-mediated processes known as the “runner’s high,” which lead to an acute improvement in mood.
The musculoskeletal system also benefits significantly from regular exercise. Through mechanical loading, both muscles and the skeletal system are strengthened. Aerobic activities promote mitochondrial density and the efficiency of energy production, while anaerobic activities such as strength training stimulate muscle growth. Chronic training also has positive effects on bone density and helps reduce body fat. However, with age, the functional capacities of the musculoskeletal system decline, a process exacerbated by hormonal changes, particularly the decrease in estrogen levels in women. These changes increase the risk of osteoporosis and osteoporotic fractures, which can be at least partially mitigated by regular exercise.
The endocrine and metabolic systems also respond positively to physical activity. Exercise improves insulin sensitivity and optimizes glucose and fat metabolism. This is particularly relevant for people with type 2 diabetes, as muscles can take up glucose even without insulin. This leads to better blood sugar regulation and a reduction in HbA1c, fasting blood glucose, and visceral fat. Furthermore, physical activity has a positive effect on the lipid profile, although the results for LDL cholesterol vary.
Another system that benefits from exercise is the gastrointestinal tract. Regular physical activity improves intestinal motility and promotes microbial diversity in the gut. These effects reduce the risk of inflammatory bowel diseases and gastrointestinal tumors, particularly colon and esophageal cancer.
The body’s response to physical activity is largely determined by genetic factors. Up to 80% of the variation in adaptation to strength and endurance performance is genetically determined. Genes that affect energy metabolism and muscular adaptation have already been identified and could drive the development of personalized training programs in the future. However, the practical application of these genetic insights in sports medicine remains limited.
Another central element in movement is the ability of muscles to contract, which is made possible by the hydrolysis of ATP. During intense exertion, ATP is generated through anaerobic processes, while during longer, sustained activities, oxidative phosphorylation comes into play, delivering greater amounts of ATP and requiring oxygen. While anaerobic metabolic pathways provide quick energy, oxidative metabolism enables longer-lasting performance.
In conclusion, regular physical activity has profound effects on the entire body. It not only strengthens the muscles and skeletal system but also has positive effects on the cardiovascular, metabolic, endocrine, and immune systems. Physical activity is one of the most effective and cost-efficient measures to improve health and prevent disease. Therefore, it is of utmost importance to consider exercise as an integral part of therapeutic and preventive approaches in modern medicine.
Source:
Matthews, M. J., Kanungo, S., Baker, R. J., & Kenter, K. (2024). Exercise Physiology: A Review of Established Concepts and Current Questions. Physiologia, 4(2), Article 2. Source
Patel, P. N., Horenstein, M. S., & Zwibel, H. (2025). Exercise Physiology. In StatPearls. StatPearls Publishing. Source
Reynolds, S. (2024, Mai 13). Understanding how exercise affects the body. National Institutes of Health (NIH). Source
Sanford, J. A., Nogiec, C. D., Lindholm, M. E., Adkins, J. N., Amar, D., Dasari, S., Drugan, J. K., Fernández, F. M., Radom-Aizik, S., Schenk, S., Snyder, M. P., Tracy, R. P., Vanderboom, P., Trappe, S., Walsh, M. J., & Molecular Transducers of Physical Activity Consortium. (2020). Molecular Transducers of Physical Activity Consortium (MoTrPAC): Mapping the Dynamic Responses to Exercise. Cell, 181(7), 1464–1474. Source