The benefits of routine exercise can be realized throughout the spectrum of one’s life. Many physiologic changes once attributed to “old age” have come into question regarding inherent physiologic change versus disuse or adaptive responses. Medical conditions including hypertension, diabetes, dyslipidemia, obesity, osteoporosis, and coronary artery disease (CAD) have been shown to be halted or slowed onset in the setting of routine exercise or addition of exercise in those previously sedentary. Advancing age traditionally leads to decreasing physical activity or incorporation of a relatively sedentary lifestyle. This is multifactorial and may include work, family, and chronic medical issues. Less than half of the U.S. adult population meets the activity recommendations of the Centers for Disease Control/American College of Sports Medicine (CDC/ACSM) and only 39% of those over 65.¹ While the “geriatric athlete” is defined as those aged 65 and up, this chapter will broaden the focus to include a much broader age range with attention to the “mature athlete” and masters-level athletes.

Masters athletes have shown that competitive exercise and “healthy aging” is possible over a broad range of ages. Masters level is defined as women and men of age 35 and up.² Both in organized team and in individual sports, age categories are in 5-year increments with the eldest category being those competitors aged 100 plus. The Senior Olympics, now known as the National Senior Games, includes athletes aged 50 and above. Originating in 1987 with 2,500 athletes, the National Senior Games is held every 2 years with 12,100 athletes registered in 2007.³ Studies in previously sedentary geriatric populations with varying levels of physical function and medical comorbidities have enjoyed the benefits of renewed exercise in their daily lives. Even in masters athletes, however, there are functional declines that are observed and may be an inevitable process of aging. The ultimate question remains, how much is preventable with exercise?

What are some of the adaptive changes associated with aging? The cardiovascular response is a 6 to 10 beats/min decline in maximum heart rate per decade. Vo₂max (maximal oxygen consumption) decreases 5% to 15% per decade after age 25.⁴ During maximal exercise, older athletes generally demonstrate higher blood pressures and peripheral vascular resistance than their younger counterparts. The pulmonary changes of decreased lung compliance (elasticity) and decreased vital capacity may also contribute to a relative increase in perceived exertion for given workload. Loss of muscle mass, also known as sarcopenia, is a prominent feature with aging. Type 2 muscle fibers show greater relative loss. Peak muscle strength is seen around age 30 and starts to decline at age 50; in the sedentary population, there is a 15% per decade decline from age 50 to 70 and a 30% per decade decline after age 70.⁵ Decreased muscle mass results in decreased lean body mass, which, in turn, leads to a lower basal metabolic rate. This decrease can contribute to central obesity and weight gain without change in caloric intake. With advancing age comes increased muscle stiffness and decreased tensile strength of tendons and ligaments. This is an important factor in the overuse injuries, and longer rehabilitation time is often needed for return to activity. Bone density declines 0.5%/year after age 40.⁶ Additionally with aging, diminishing balance and coordination contributes to increased risk of falls and injury. More recently, mitochondrial dysfunction has been identified in the aging process. This dysfunction appears to stem from both electron transport chain defects and uncoupling of oxidative phosphorylation due to hydrogen leak in the inner mitochondrial membrane. These changes lead to reduced ATP generation per mitochondrion and reduced exercise efficiency with reduced ATP synthesis per O₂ uptake.⁷ The ATP depletion at the cellular level due to the uncoupling with age is associated with apoptosis (cell death). The uncoupling is seen to a greater extent in muscles with higher percentage of type 2 fibers and may explain the preferential loss noted earlier in the text⁷ (see Table 25.1).

So, with these declines, can exercise bring hope? Studies among masters athletes have shown promise. The keys to changing course include restoring fitness and maintaining a balance of cardiovascular and strength training. Some studies have shown a decrease in the rate of decline in heart rate max and Vo₂max with maintained levels of training. More benefit may be realized in risk reduction for the associated
comorbidities of sedentary lifestyle listed previously. Strength training in the elderly, which had often been dismissed previously, is now considered a vital component of fitness. Even the frail elderly can achieve muscle hypertrophy and increased size of muscle fibers. The benefit not only goes beyond strength itself but also contributes to maintaining balance and, in turn, fall prevention. Strength training in the frail has also demonstrated increased spontaneous activity by those previously sedentary. Bone mineral density may be improved with exercise. Activities with higher loading forces have shown greater responses to increasing bone mineral density. However, this higher impact is not always practical in the geriatric athlete. For those with osteoarthritis (OA), low-impact exercise has been shown to improve both pain and function.⁶,⁸ Even with relatively small blood pressure reduction, risk reduction of stroke and CAD can be significant in the general population.⁹ At the cellular level, reversal of mitochondrial dysfunction, uncoupling of oxidative phosphorylation, has been shown after 6 months of exercise training in elderly muscle.⁷

Vital to success of training and competition is setting and modifying goals as needed with appropriate activities for the individual. For instance, the sedentary individual who was an “athlete” years ago and is now planning to “get back into shape” or perhaps train for a marathon would need much different education than the age-matched individual who has continued to compete and whose goal is to improve his or her finish time in the same event. Overuse injuries are especially common in the mature athlete and may account for up to 70% of injuries in experienced athletes over the age of 60.¹⁰ This may often be attributed to training errors including rapid increase in activity with inadequate recovery time, improper footwear, poor biomechanics, or training surfaces. Because of physiologic changes, recovery time for injuries is generally longer in the elder athlete. With advancing age, the thirst mechanism becomes impaired and this may put an athlete at increased risk for dehydration. Thermoregulation may also be impaired in the setting of autonomic dysfunction. In addition, certain medications, such as diuretics or β-blockers, may have side effects unsuitable for the competitive athlete. Knowledge of the athlete’s medical comorbidities is imperative in counseling and physical assessment.

Prior to initiating an exercise program or significantly increasing physical activity in the mature population, one must first determine medical readiness and whether medical “clearance” is indicated. Though recommendations vary, the goal of screening is for risk stratification and identifying need for further evaluation and/or treatment prior to participation. Specific goals are to identify CAD risk factors and signs and symptoms (or current status if preexisting) of cardiovascular, pulmonary, or metabolic disease. Screening questionnaires such as American Heart Association (AHA)/ACSM Health/Fitness Preparticipation Screening Questionnaire and the PAR-Q (Physical Activity Readiness Questionnaire) may help identify those in need of further medical screening.¹¹,¹²,¹³ In the absence of a positive screen, individuals are encouraged to gradually increase their level of physical activity as tolerated without need for further testing. However, this requires the participant to be current with general age-appropriate medical screenings, such as blood pressure.