Age and Exercise


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Background

Even without the presence of disease, a person's body will undergo changes in it's structure and function . Skeletal and cardiac muscle adaptations occur because of changes in intensity, duration, and frequency of physical activity (increase or decrease). The adaptations include alterations in morphological, biochemical, and molecular properties. These adaptations in turn lead to altered functional characteristics from the cellular to the whole tissue and functional performance levels. It has been reported that rates of physical activity decline with age and the risk of chronic disease increases which compound the changes to muscle and bone.

The good news is that there is evidence that physical exercise provides a myriad of benefits. Regular physical exercise can reduce the risk of chronic disease and increase life expectancy as well as produce improvements in muscle function (strength and power). Multi-modal exercise has a reported beneficial effect on falls prevention

Much research, including large scale systematic reviews, have studied what effect exercise has on the older adult for improving muscle strength, aerobic capacity (VO2max) and functional outcomes. Guidelines have been proposed to optimise exercise prescription for the older adult . These guidelines recommend endurance training, resistance exercise, flexibility and balance exercises.

There is no consensus in literature for the age range which defines the older adult, or elderly. In general, guidelines suggest that those 65 years or older can be considered older adults.

Strength Training

The very old and frail elderly experience sarcopenia (skeletal muscle atrophy) as a result of one or a combination of disuse, disease, injury, malnutrition and the effects of ageing. Muscle weakness that accompanies advanced age has been related to the risk of falling and fracture in these older individuals. One of the best ways to keep muscles healthy and strong is through exercises called strength training—sometimes known as weight lifting or resistance training. Studies demonstrate that frail elderly men and women retain the capacity to adapt to resistance exercise training with significant and clinically relevant muscle hypertrophy and increases in muscle strength.

Strength training, or progressive resistance strength training (PRT), is generally defined as training in which the resistance against which a muscle generates force is progressively increased over time. The maximal weight or resistance a person can lift or move to complete the movement is defined as one repetition maximum (1 RM). Prescriptions of repetitions at what RM vary depending on prior experience with PRT and comorbidities. One recommendation (Level IIA evidence) from the American College of Sports Medicine and the American Heart Association suggests "8–10 exercises be performed on two or more nonconsecutive days per week using the major muscle groups". The guideline also suggests 10-15 repetitions with a weight for resistance at a intensity of 5 or 6 on a ten point scale.

The muscle hypertrophy and increased strength, along with the changes in body composition and hormonal and nervous system adaptations associated with strength training, have a positive impact on the daily activities of living and functional independence of the older adult. In frail elderly living in a nursing home, a high-intensity progressive resistance training program of 8 weeks' duration increased strength on the average of 1749'0, with a mean increase in muscle cross-sectional area of 150/oY These increases in muscle size and strength were associated with clinically significant improvements in gait speed, balance, and functional independence. Strength training can also have substantial benefits for protection from injury in the elderly, as falling is strongly related to hip weakness, poor balance, and postural sway.

Aerobic Exercise

Aerobic exercise takes place in the presence of oxygen and involves aerobic metabolism of glucose. The exercise is low in intensity and sustained for a longer period than strength training.

Older individuals show an increase in oxidative capacity of the skeletal muscles (VO2max) after PRT. The skeletal muscle glycogen stores in the older adults are lower than those of the young adults initially but increase significantly with exercise. The skeletal muscles of older adults increase in capillary densities, mitochondrial enzyme levels, and ability of muscles to extract oxygen from the blood. These skeletal muscle adaptations contribute to the rise in Vo2max in the elderly with training,

Although both older men and women respond to endurance training with an increase in Vo2max, the mechanism of adaptation is also different. In older men, two thirds of the increase in Vo2max is due to an augmented cardiac output and one third is due to a wider a-v02 content difference. On the other hand, in older women, there is a similar increase in Vo2max with training; however the changes in left ventricular systolic performance and diastolic-filling dynamics do not occur. Thus, the increase in Vo2max in older women is due to peripheral adaptations that lead to the enhanced a-V02 content difference. Peripheral adaptations include increases in skeletal muscle capillarization and activity of mitochondrial marker enzymes, e.g., citrate synthase.A decline in maximal aerobic capacity occur across adult age-span accelerating later years

Flexibility exercises

Older adults adopt certain movement patterns and postures as they age due to habit, injury or disability. Oftentimes, these movement patterns and acquired postures result in muscles and other soft tissue that is continuously held in a shortened or lengthened position. This sustained change in length of the muscle and other soft tissues (e.g. fascia Stretching is indicated to promote adaptation of shortened muscles to a more lengthened position to achieve better posture and movement patterns. Muscles held in shortened positions appear to have a biased muscle spindle that may lead to active and passive resistance to increased length, resulting in muscle imbalance during movement and even painful movement patterns.

• Research has shown that with increasing age and a loss of extensibility, effective stretching exercises require longer holding times. Although a 30-second hold is sufficient to achieve a long-term effect of muscle lengthening in a younger adult, 60 seconds is necessary for adults age 65 years and older.
• Four repetitions of a 60-second hold performed regularly, 5 to 7 days a week, appear to be most effective.
• Some have suggested the use of ballistic or dynamic stretching to increase immediate muscle performance.
• Slow static stretching is likewise recommended for stretching the collagen tissue that is the substance of these structures.

Aquatic Exercises

Application of PST for individuals who cannot tolerate the stress of land-based exercises. Not only does the water provide the necessary resistance for working out your muscles and joints, it also provides a low-impact environment for doing so--a benefit to seniors with arthritis and joint pain.

• Measurement: Kruel Method
• Subjective: PRE Scales
• Indications: OA, Overweight patient, undergone surgery, significant balance disorder, fear of falling
• Contraindications & Safety:
• Equipment: Floating devices, sling-type walking devices, underwater treadmill systems, AED

Plyometrics

Plyometric exercise is an attempt to use the stretch reflex of the muscle spindle and the elastic energy that is stored in a stretched muscle to enhance an immediate reciprocal contraction in that muscle.these exercises were designed to increase speed, power, and explosiveness.

Plyometrics usually consists of an eccentric (lengthening) contraction followed by a concentric (shortening) contraction of the same muscles
Plyometric exercise is meant to result in an increase in the ballistic ability of the muscle, that is, the ability to increase the explosiveness of the muscle contraction

Reversing Decline

Although both aerobic and resistance training are recommended to improve muscular function in the elderly, only resistance training can reverse or delay the decline in muscle mass and strength with aging. Increased strength and mass can be important steps in maintaining daily functional activities of independence in older persons in whom "disuse" atrophy has limited their daily activities. Aerobic exercise has long been an important recommendation for those with many of the chronic diseases typically associated with old age. These include non-insulin-dependent diabetes mellitus, hypertension, heart disease, and osteoporosis. The incorporation of aerobic and resistance exercise training into the life-style of older individuals can have a considerable impact on the functional capacity, physiological reserve, and independence

Risks of Exercise

The possible adverse effects of exercise that are most worrisome are sudden death, injury, and osteoarthritis. The most serious but least common ofthese is sudden death, defined as death occurring either during the actual activity or within 1 hour after it. Although reported rates of sudden death vary from 4 to 56 times greater than chance, the absolute risk is low: one cardiac death per 396,000 hours of jogging or one death per 15,000 to 18,000 exercises per year.64
There are few data on the risks of injury associated with the physical activities performed by older adults, such as walking and gardening. Injuries sustained by participants in organized exercise programs, which are primarily due to overuse, are relatively common. The ankle is the joint most likely to be injured. Most nontraumatic musculoskeletal injuries in runners are directly related to distance run and increasing mileage. Age and obesity do not appear to be contributing factors in current studies. There are no good.
studies of nontraumatic musculoskeletal injuries related to walking, cycling, or gardening

The fear that the physical activity may stimulate osteoarthritis or exacerbate a pre-existing condition has kept some older adults from participating in an exercise program and may prevent health care professionals from recommending that they do so.

Case Study

http://exerciserx.cheu.gov.hk/files/DoctorsHanbook_ch14.pdf

Resource:

http://growingstronger.nutrition.tufts.edu/growing_stronger.pdf