How does aging typically affect physical fitness levels?

As individuals age, one of the most common physiological changes is the reduction in muscle mass and aerobic ability. This decrease is primarily due to a combination of factors such as hormonal changes, decreased physical activity, and the natural aging of muscle fibers. Muscle mass typically decreases because the body undergoes a process known as sarcopenia, where muscle tissue diminishes over time. This loss of muscle can lead to reduced strength and endurance, making it more challenging for older adults to perform physical tasks.

Aerobic ability, which refers to the body's capacity to take in and utilize oxygen during exercise, also declines with age. This decline can result from changes in the cardiovascular system, including reduced maximal heart rate and diminished oxygen transport. Consequently, older adults may find it harder to maintain their previous levels of physical fitness and might experience fatigue more quickly than in their younger years.

In contrast, the other options suggest improvements or enhancements that are typically not associated with the aging process. Increased muscle flexibility, higher aerobic capacity, and enhanced coordination are generally not observed trends in older adults; instead, physical fitness often requires more intentional and focused training to maintain or improve these attributes as one ages.