Aging And Athletes: How Exercise Can Make A Difference
Impaired balance and concern about falling are two of the most often cited reasons for decreased activity in older individuals.12 Most acute injuries in older people are related to falls or slips.13,14 Research shows that training balance and lower extremity strength simultaneously is an important strategy in maintaining physical function and decreasing the risk of falls.15,16
Age-related decline in muscle function in theory has the greatest impact on functional muscle capacity.11 There is a 20 to 40 percent decrease in strength between the ages of 20 and 70.17,18 Sarcopenia describes the process of muscle deterioration, which includes a reduced number and size of muscle cells, and a decreased density of mitochondria. Sarcopenia results in decreased muscle power and endurance. Wolfson and colleagues showed strength and balance improvements in older adults with a lab-based training program.15 The older adults in the study then transitioned to a tai chi program and were able to maintain the gains but to a lesser degree. The preservation of muscle power into late life can greatly decrease the risk of disability and enhance functional independence.19
Aging itself is not a risk factor for tendon injuries but changes to the cellular matrix of tendons occur with age.20 Increased collagen, decreased collagen turnover, increased cross-linking and changes in elastin and water content all lead to altered tendon stiffness. Diabetes can accelerate the changes in aging tendon.21 Research has shown physical activity to increase the cross-sectional area of tendons while enhancing collagen turnover and remodeling.22 Individuals who continue to exercise and incorporate flexibility and eccentric strength training slow the decline in flexibility one would otherwise see with aging.11
What The Literature Reveals About Bone And Cartilage Changes
Common changes to the bone of older individuals include: decreased bone mineral density, thinner cortex adipose tissue deposits in marrow and decreased osteoblast activity. These affect women earlier and more significantly than men.3 In fact, women start losing bone mineral density in their 30s and lose it twice as fast as men.23 Physical exercise, including resistance, aerobic and endurance training, all help maintain and improve bone health.24
Cartilage relies on joint loading and the fluid dynamics of synovial fluid for nutrition and removal of metabolic waste. Chondrocytes and extracellular matrix proteins experience little cell turnover so they may be less resistant to aging than other tissues. In addition, the increased oxidative stress and decreased growth factors present in aging cartilage may contribute to the development of osteoarthritis.25 Decreased joint loading, similar to what occurs with even short-term immobilization, results in disuse atrophy and the diminished metabolic activity of cartilage.26
Osteoarthritis is the most common source of musculoskeletal pain and disability in the older population.9 Softening, fissuring and fibrillation of the weightbearing surfaces occur with repetitive joint loading and microtrauma to mechanically compromised articular cartilage.23 Activities that subject the joints to high levels of impact and torsional loading may increase the risk of injury and cartilage degeneration.27,28 Individuals with early osteoarthritis can benefit from regular exercise but one should advise them to select activities that maintain joint motion and build strength with minimal loading of the affected joints.28 For example, runners who develop knee osteoarthritis may transition to cycling or elliptical exercise machines to minimize knee joint loading.