The process of aging is intricate, influenced by various factors that interact with each other. These
factors encompass lifestyle choices and genetic elements. As people grow older, they experience
physiological changes that lead to a decline in functional capacity and alterations in body
composition. Simultaneously, there is a decrease in both the volume and intensity of physical
activity. The variance in the aging process among older adults can be attributed to a combination of
genetic and lifestyle factors.

Scientific evidence corroborates the notion that regular physical activity can enhance the average
lifespan by affecting the development of chronic diseases. Nevertheless, individuals exhibit
substantial diversity in their aging processes and their responses to exercise programs. The latest
guidelines from the American College of Sports Medicine (ACSM) emphasize that both aerobic
exercise and resistance training can increase aerobic capacity and muscle strength in older adults by
20%–30% or more. This helps mitigate the physiological effects of a sedentary lifestyle and extends
active life expectancy by reducing the onset and progression of chronic diseases and disabling
conditions.

The ACSM Position Stand classifies the strength of evidence obtained from literature analysis into
four categories:

1. Evidence Level A: This category is supported by overwhelming evidence from randomized
   controlled trials and/or observational studies, which consistently reveal substantial data.
2. Evidence Level B: Strong evidence emerges from a combination of randomized controlled trials
   and/or observational studies. However, some studies within this category may yield results that are
   inconsistent with the overall conclusion.
3. Evidence Level C: Generally positive or suggestive evidence is found in a smaller number of
   observational studies and/or uncontrolled or non-randomized trials.
4. Evidence Level D: When the strength of the evidence is deemed insufficient to place it in
   categories A through C, panel consensus judgment falls into this category.

In the ACSM Position Stand, significant evidence is categorized as follows:

• Evidence Category A: Regular physical activity enhances average life expectancy by influencing the
  development of chronic diseases, mitigating age-related biological changes, preserving functional
  capacity, and promoting overall health and well-being.
• Evidence Categories B/C: Regular physical activity positively impacts a wide range of physiological
  systems, potentially differentiating between individuals who age successfully and those who do not.
• Evidence Category B: Vigorous, long-term participation in aerobic training leads to increased
  cardiovascular reserve and skeletal muscle adaptations in older individuals. This enables them to
  endure submaximal exercise loads with reduced cardiovascular stress and muscular fatigue
  compared to their untrained peers. Prolonged aerobic exercise also appears to slow down the age-
  related accumulation of central body fat and provides cardioprotection.
• Evidence Category A: Older adults can significantly enhance their strength and muscular power
  through resistance training.
• Evidence Category B: Improvements in muscle quality are similar between older and younger
  adults, with no apparent sex-specific differences.