Age influences metabolic rates and fitness due to natural physiological changes over time. As individuals age, their basal metabolic rate (BMR) tends to decline, often resulting in weight gain if caloric intake is not adjusted. Muscle mass typically decreases, which can further lower metabolic rates since muscle tissue burns more calories at rest than fat tissue. Older adults may also face challenges in recovery times and flexibility, impacting their fitness levels. Adapting fitness programs to accommodate these changes is crucial for improving health and maintaining an active lifestyle as one ages.