Human movement relies on three energy-creating systems. The phosphate system gets you started. The anaerobic system kicks in within about a minute. And, the aerobic system keeps you moving for long periods. All systems need adenosine triphosphate. Many people refer to this important substance as "molecular currency." Researchers once thought that running out of adenosine triphosphate created feelings of fatigue. They now know, however, that your body fatigues to conserve this substance. Nonetheless, breaking down your adenosine triphosphate creates unwanted byproducts.
Exercise and Heat
All physical activities burn calories and produce heat. During exercise, this heat leaves the body, transfers to the environment and gradually decays. The authors of a January 2017 report in the International Journal of Medical, Health, Biomedical, Bioengineering and Pharmaceutical Engineering state that you convert more adenosine triphosphate to heat than work. In fact, about 67 percent of your adenosine triphosphate dissipates into the environment, doing nothing, therefore, to help fuel your workout. Interestingly, the authors of the January 2017 report also show how this percentage increases as you get older. Yet, doing regular exercise can help you fight these age-related changes.
Exercise and Free Radicals
Resting and working muscles also generate free radicals like nitric acid. Your cells use these natural byproducts to communicate with each other and to support metabolic balance. Yet, excessive production of free radicals during times of stress can damage your body. It may, for example, play a role in the brain changes seen in Alzheimer's disease. A September 2016 paper in Free Radical Biology and Medicine reviews the research showing how exercise lowers reactive free radicals. Interestingly, these effects occur in both the skeletal system and the immune system. The latter finding suggests that exercise bolsters your ability to fight sickness and disease.
Aerobic Exercise and Carbon Dioxide
Using oxygen to fuel your aerobic activities causes the release of carbon dioxide. Typically considered a byproduct, carbon dioxide production actually plays many important roles in exercise physiology. For example, exercise-induced carbon dioxide production opens up your blood vessels. It also lowers your pH. These changes let you quickly move oxygen from your blood to your muscles. The authors of a July 2018 article in the Journal of Physiological Sciences speculated that these changes would alter muscle architecture. The researchers infused the muscles of rats with carbon dioxide. This infusion increased the slow-twitch content of the muscles. Runners often see a similar change as they increase their endurance. These results show that aerobic exercise will improve your muscle development and enhance your exercise recovery.
Anaerobic Exercise and Lactic Acid
Scientists have long known that intense exercise increases lactic acid. A July 2018 report in Frontiers in Physiology looked at this effect in both women and men. These researchers also had an interest in participant response to the exercise-induced increase in free radical production. Sprinting on an exercise cycle for a mere 20 seconds dramatically increased lactic acid. This change happened within three minutes. The sprint also triggered antioxidant release, but this effect followed a different timeline. The participants had lower antioxidant production 15 minutes after sprinting. Fortunately, a later increase followed this first decrease. In fact, antioxidant production eventually exceeded baseline levels. The researchers also found that better sprinters had larger antioxidant responses. The latter finding suggests that anaerobic exercise offers you an easy, safe way to enjoy the many benefits of getting antioxidants.
- International Journal of Medical, Health, Biomedical, Bioengineering and Pharmaceutical Engineering: Effect of Aging on the Second Law Efficiency , Exergy Destruction and Entropy Generation in the Skeletal Muscles During Exercise
- Free Radical Biology and Medicine: Physical Exercise, Reactive Oxygen Species and Neuroprotection
- Journal of Physiological Sciences: Increase in Carbon Dioxide Accelerates the Performance of Endurance Exercise in Rats
- Frontiers in Physiology: Anaerobic Exercise-Induced Activation of Antioxidant Enzymes in the Blood of Women and Men
- Photodisc/Photodisc/Getty Images