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Exercise and diet: implications for the elderly

Jane Griffin
BSc(Nutrition) RD RNutr
Sports Dietitian and Nutrition Consultant

In 2004 the Chief Medical Officer produced a report At Least Five a Week which provided evidence on the impact of physical activity and its relationship to health.(1) The chapter on the benefits of physical activity for older adults makes for particularly interesting reading. Anybody with ideas that they are too old to start being more physically active should certainly think again.
Beneficial effects of physical activity on heart disease, stroke, type 2 diabetes and obesity are all evident in older people. Regular lifestyle activity can also help older people keep mobile and live independently. Physical activity that improves strength, balance and coordination can help reduce the incidence of falls and make, what in years gone by were simple tasks (such as getting up out of a chair), slightly easier.
It can help improve the emotional and mental wellbeing of older people. Studies have shown that more active older people are less tense and anxious and show improvements in overall feelings of general wellbeing. Regular physical activity may possibly help memory too.(2) A study published in 2002 showed that 65 year olds and older who were physically active had a 31% lower risk of developing Alzheimer's disease when compared with inactive peers.(3) Aerobic exercise training (eg, brisk walking, swimming, water aerobics) has also been reported to increase vigour and reduce fatigue in studies that have included older people.(4) An increase in physical activity has even been shown to improve sleep in older people.(5,6)

Changes in body composition and weight with age
As people get older they tend to lose lean body mass as a result of a loss of skeletal muscle. However, if physical activity is maintained or even increased this reduction becomes less marked. As muscle is lost with age, there is an increase in body fat (see Table 1).(7)

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Not only does body fat content change with age, but the distribution also changes. Body fat tends to accumulate more around the abdomen and less on the limbs. This has health implications as abdominal obesity increases cardiovascular disease risk and may also cause glucose intolerance and raised insulin levels, which increase the risk of type 2 diabetes developing. Although genetic factors are certainly involved in the fat mass and fat-free mass changes that occur with age, research does suggest that regular exercise is important in achieving and maintaining optimal body composition with ageing. More specifically both aerobic and resistance exercise should be undertaken. Aerobic exercise appears to help reduce weight and fat mass, but does not provide a strong enough stimulus to promote muscle growth and increase muscle mass. Resistance training is not only effective in decreasing fat mass in older people, but in most cases it also increases fat-free mass too.
Physical activity patterns show a decline with age, so in general there is a progressive fall in energy expenditure. However, there is a lot of variation in activity levels at all ages, and an active 70-year-old could have an energy expenditure similar to a sedentary 40- year-old. In addition the cost of physical activity may increase with age due to less efficient movement. It has been shown that women in their 80s use more energy walking than women in their 30s.(8)

How can older people be more active?
In his report, the Chief Medical Officer gave specific guidelines for physical activity for older people which had not previously been established in England. "The evidence suggests that: the recommendations for adults are also appropriate for older people." In other words, older people should achieve a total of at least 30 minutes of moderate intensity physical activity a day, on five or more days a week. However, he stated that there are some important considerations for older people.

  • Take particular care to keep moving and retain mobility through daily activity.
  • Activities should promote improved strength, coordination and balance, in addition to endurance.
  • Choices of activities should take into account functional limitations and disease symptoms.
  • Regular walking is very important to help maintain independence and activities of general daily life.
  • Only low-to-moderate intensity activities can produce a health benefit in older people, ie, the absolute intensity of activities for older people can be lower than it is for younger adults.
  • There is a greater risk of injury among older people so higher-intensity activities and those involving sudden or complicated movements should be undertaken cautiously, unless the individual is already used to that type of exercise.

Examples of light intensity exercise include ironing, cleaning, dusting and walking/strolling (2 mph). Moderate exercise includes painting/decorating, walking (3 mph), vacuuming, golf (walking and pulling clubs), social badminton, tennis doubles, brisk walking (4 mph), mowing grass (walking, using power-mower) and cycling (10-12 mph). Many of these activities can be undertaken on a regular if not daily basis - some achieved by accomplishing daily chores (eg, walking to post a letter or do the shopping) while other can be incorporated into more social aspects of the day (eg, playing golf, tea dances, and so on). Some older people will prefer to achieve their recommended activity level by more formal exercise, eg, weights sessions in the gym, yoga, Pilates or T'ai Chi classes. If someone experiences an increase in respiration rate, an increase in heart rate and a feeling of increased warmth, possibly with sweating on hot or humid days, while exercising, they will almost certainly be working at a moderate intensity.

Fuelling activities
By being as physically active as possible on a daily basis, older people can enjoy more food than their more inactive friends and relatives, but energy needs may still be lower than in years gone by. It is therefore important that foods chosen are micronutrient dense so that nutritional requirements for minerals and vitamins are met as well as overall energy requirements. This can be achieved by enjoying a wide variety of foods from the basic food groups (see Table 2). Putting foods into groups according to the main nutrients they supply makes it easier to choose wisely but enjoyably. Those who eat the correct proportions of foods from the main food groups every day, and vary the choices within each group, will be eating well and therefore, probably enjoying and getting more out of their chosen physical activities.

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Keeping up the fluid
Older people who exercise are at greater risk of dehydration and heat-related injuries than younger people. Renal function is lowered and there is a decreased ability to concentrate urine. This can lead to an impaired ability to maintain body temperature during exercise in hot or humid conditions. Heat intolerance in older people seems to be related in the main to a decrease in physical fitness. A fit older person will have a greater tolerance to exercise in the heat than those of a similar age who lead a very sedentary lifestyle. However, the thirst sensation tends to decrease with age in everyone. Active healthy men aged 67-75 years have been shown to be less thirsty and voluntarily drink less water when water deprived for 24 hours than similarly deprived men aged 20-31 years. Older people therefore need to hydrate before exercise, keep drinking throughout exercise, avoid waiting for the thirst mechanism to kick in before drinking and to continue drinking, after stopping exercise until totally hydrated again.

Conclusion
Keeping physically active and eating a well-balanced diet cannot stop the years ticking by, but they may well help to keep people healthy, active and independent well into old age.

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References:

  1. Department of Health. At Least five a Week. Evidence on the impact of physical activity and its relationship to health. A report from the Chief Medical Officer. London; DH; 2004.
  2. Colcombe S, Kramer AF. Fitness effects on the cognitive function of older adults: A meta-analytic study. Psychol Sci 2003;14:125-30.
  3. Lindsay J, Laurin D, Verreault R, et al. Risk factors for Alzheimer's disease: a prospective analysis from the Canadian study of health and aging. Am J Epidemiol 2002;156:445-53.
  4. Satcher D. An overlooked global health concern. JAMA 2000;284:950.
  5. King AC, Oman RF, Brassington GS, Bliwise DL, Haskell WL. Moderate-intensity exercise and self-rated quality of sleep in older adults: A randomised controlled trial. JAMA 1997;277:32-7.
  6. Naylor E, Penev PD, Orbeta L, et al. Daily social and physical activity increases slow-wave sleep and daytime neuropsychological performance in the elderly. Sleep 2000;23:87-95.
  7. Young VR. Macronutrient needs in the elderly. Nutr Rev 1992;50:454-62.
  8. Bassey EJ, Terry AM. The oxygen cost of walking in the elderly. J Physiol 1986;373:42.