Question

There is something that appears as a contradiction to a newbie like me.

Sport is widely recognized as healthy and recommended by medical experts.

Metabolic rate is inversely correlated with lifespan.

To me, it makes sense that the more energy passes through your system, the more it gets damaged.

Sport goes against this desirable frugality, as it makes you consume more energy, which requires increasing your energy input to compensate (you eat more food). Also, growing a greater muscular mass increases the amount of energy needed for moving, for maintaining body temperature at rest; having more cells mean larger amounts of oxygen are needed, more DNA-copying errors are made, more free radicals are produced, etc.

At the same time, I've heard that sport is good because it lowers heartbeat at rest, it makes special immune-system agents enter cells more effectively, and other things...

I'm obviously missing something, but I'm just having a hard time understanding how something that increases the entropy of your system can be beneficial for your health in the long run.

Answer 1

Engaging in regular physical activity increases metabolic rate and muscle mass, which leads to higher energy consumption. However, exercise also brings various benefits such as improved cardiovascular efficiency and metabolic efficiency that outweigh the energetic costs, contributing to better long-term health. The complexity of living systems means that the relationship between metabolic rate and lifespan requires a nuanced understanding.

Step-by-step explanation:

It's natural to wonder how engaging in sports, which increases metabolic rate and energy consumption, can be beneficial for longevity when higher metabolism is inversely correlated with lifespan. However, this perspective overlooks the complex adaptations the body undergoes with regular exercise. While it is true that more muscular mass requires more energy, leading to a higher basal metabolic rate (BMR), exercise also enhances various bodily functions including cardiovascular health, immune response, and metabolic efficiency.

Regular physical activity leads to an increase in BMR, resulting in a higher rate of energy expenditure even at rest. Athletes tend to have a higher BMR due to increased muscle mass. However, this is balanced by the body's adaptation to exercise, through improved cardiovascular efficiency and stronger muscles which are then able to do more work with less effort. In addition, while exercising does increase the amount of oxygen consumed and can lead to more free radicals, the body's defenses such as antioxidants are also upregulated in active individuals. Furthermore, while the body adjusts its metabolic rate to partially compensate for variation in food intake, the inefficiency of the body in converting internal energy to work means that more energy is used during exercise than the work output would suggest, aiding in weight management.

It should be noted that humans are not in thermal equilibrium, and living systems are highly complex. The seemingly increased entropy in the system from exercise is managed by the body's remarkable ability to repair itself, adapt to increased demands, and optimize its functioning—benefits that ultimately contribute to better long-term health. Therefore, the relationship between metabolic rate and lifespan is not as straightforward as it may seem, and physical activity remains a cornerstone of health recommendations.