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Introduction

Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity (WHO, 1946). There are many factors which have an impact on health and quality of life, including lifestyle choices of each individual. Diets high in fruits and vegetables and participation in regular physical activity are associated with a lower risk for several chronic diseases and conditions (US department of health and human services, 2005).

Physical inactivity is very common globally with 31% of adults over 15 years old being insufficiently active. Insufficient physical inactivity results in about 3.2 million deaths per year (WHO, 2008).

Elder adults are generally more vulnerable to malnutrition. This is because both lean body mass and basal metabolic rate decrease with increasing age. It has been found that many diseases suffered by the older people are diet- related. Other factors contributing to malnutrition include dietary, psychosocial, physiological and economic changes (DiMaria-Ghalili, R. A., & Amella, E., 2005).

Global Recommendations on physical activity for 65 years and above according to the WHO

1. Older adults should do at least 150 minutes of moderate-intensity aerobic physical activity throughout the week or do at least 75 minutes of vigorous intensity aerobic physical activity throughout the week or an equivalent combination of moderate- and vigorous-intensity activity.
2. Aerobic activity should be performed in bouts of at least 10 minutes duration.
3. For additional health benefits, older adults should increase their moderate intensity aerobic physical activity to 300 minutes per week, or engage in 150 minutes of vigorous-intensity aerobic physical activity per week, or an equivalent combination of moderate-and vigorous-intensity activity.
4. Older adults, with poor mobility, should perform physical activity to enhance balance and prevent falls on 3 or more days per week.
5. Muscle-strengthening activities, involving major muscle groups, should be done on 2 or more days a week.
6. When older adults cannot do the recommended amounts of physical activity due to health conditions, they should be as physically active as their abilities and conditions allow.

Inactive people should start with small amounts of physical activity and gradually increase duration, frequency and intensity over time. Inactive adults and those with disease limitations will have added health benefits when they become more active. (WHO, 2011)

Physical activity and bone loss

Exercise plays an important role in building and maintaining bone and muscle strength. Physical activity positively influences most structural components of the musculoskeletal system that are related to functional capabilities and the risk of degenerative diseases. Physical activity also has the potential to postpone or prevent prevalent musculoskeletal disorders, such as mechanical low back pain, neck and shoulder pain, and osteoporosis and related fractures. Exercise can contribute to the rehabilitation of musculoskeletal disorders and recovery from orthopedic surgery.

Muscles and bones respond and strengthen when they are ‘stressed’. This can be achieved by weight bearing or impact exercises which make the bones denser. Physical activity helps prevent weak bones and falls in the elderly. One-third of people over 65 have a fall each year and the risk of falling increases as age rises. People who have suffered fractures can benefit from special exercises and training (under medical supervision) to improve muscle strength and muscle function for greater mobility and improved quality of life.

Balance training and Tai chi have been shown to decrease falls by 47% and reduce the risk of hip fracture by approximately 25%.

Physical activity and hypertension

Hypertension is defined as the constant pumping of blood through blood vessels with excessive force (WHO, 2011).

Hypertension prevalence increases with advancing age and is higher in men than in women until the age of 55 years, but is slightly higher in postmenopausal women (Kannel WB, 2003). According to the 2009 NCD report, 38.1% of Mauritian people aged 65 and older were considered as hypertensive but were not on medications. 45.5% were being treated for hypertension.

Hypertension is the major risk factor for stroke, heart failure, and coronary artery disease in older adults, while all of these disorders are important contributors to mortality and functional disability.

Primary hypertension is the result of multiple conditions, such as genetic, nutritional, psychosocial, and life style factors. One of the life style factors leading to hypertension is obesity, which is usually related to a sedentary life style and inadequate physical activity. Since most elderly people have an inactive routine, they are at a much higher risk of developing high blood pressure. Therapeutic lifestyle changes, such as reduced dietary sodium intake, weight loss, regular aerobic activity, and moderation of alcohol consumption, have been shown to benefit elderly patients with hypertension. Regular aerobic exercise, consisting of a minimum of 30 min of interval training on a treadmill done three times a week, has been shown to be well tolerated and beneficial (Westhoff TH et al., 2007).

The physiological effects of exercise on hypertension are complex and not fully understood. Specific mechanisms have been found to be relevant. An immediate (acute) reduction in BP following exercise has been termed ‘post-exercise hypotension’ and is agreed to be caused by reductions in vascular resistance. (Hamer, 2006). The chronic benefits can be partially explained by a decreased systemic vascular resistance in which the autonomic nervous system and renin-angiotensin system are most likely the underlying regulatory mechanisms (Cornelissen and Fagard, 2005). Another factor contributing to this decrease in vascular resistance is the increase of nitric oxide production (from different sites in the body) causing a vasodilation in response to regular aerobic exercise.

Physical exercise and diabetes

Diabetes is a chronic disease, which occurs when the pancreas does not produce enough insulin, or when the body cannot effectively use the insulin it produces. This leads to an increased concentration of glucose in the blood (hyperglycemia).

Diabetes is classified in three main categories:

• Type 1 diabetes (also known as insulin-dependent)
• Type 2 diabetes (also called non-insulin-dependent)
• Gestational diabetes

347 million people worldwide have diabetes (Danaei G et al., 2011). The prevalence of diabetes in adults aged 20-74 years was 21.3%: 21.9% in men and 20.6% in women (NCD report, 2009).

Physical activity plays an important role in the management of type 2 diabetes, particularly glycemic control (Canadian Diabetes Association Clinical Practice Guidelines Expert Committee, 2003., Zinman B, et al., 2004., Boule NG et al., 2001., Ronnemaa T et al., 1986) and improvements in cardiovascular risk profile such as decreased hyperinsulinemia, increased insulin sensitivity, reduced body fat, decreased blood pressure and better lipid profiles (Lehmann R et al.,1997., Schneider SH et al.,1992).

Regular moderate physical activity and cardiorespiratory fitness are also associated with reductions in mortality of approximately 45 to 70% in type 2 diabetes populations (Wei M, Gibbons, et al., 2000) Moreover, regular moderate physical activity can decrease glycosylated hemoglobin (A1C) to a level associated with reduced risk of diabetic complications (Boule NG et al., 2001) and is therefore favorably delaying the onset of type 2 diabetes in high-risk groups (Knowler WC et al., 2002., Lindstrom AM et al., 2003).

The decline in insulin sensitivity with aging is relatively due to a lack of physical activity. It is likely that maintaining better levels of fitness in the older population will lead to less chronic vascular disease and an improved quality of life (ADA, 2004).

Physical activity and obesity

Obesity is defined as an unhealthy excess accumulation of fat in the body, which increases the risk if medical illness and premature mortality. It is due to an imbalance between energy intake and energy expenditure. Physical activity contributes to the creation of an energy deficit by increasing total energy expenditure, and this can promote weight loss.

Aging is associated with a decrease in all major components of total energy expenditure (TEE) including resting metabolic rate (RMR; which accounts for ≈70% of TEE), thermic effect of food (which accounts for ≈10% of TEE), and physical activity (which accounts for ≈20% of TEE). Physical activity decreases with increasing age, and it has been estimated that decreased physical activity accounts for about one-half of the decrease in TEE that occurs with aging (Elia M, Ritz P, Stubbs RJ., 2000).

Hormonal changes such as reduced responsiveness to thyroid hormone, decreased secretion of growth hormone, decrease in serum testosterone and resistance to leptin that occur during aging can also enhance the accumulation of fat ( American Journal of Clinical Nutrition, 2005).

Obesity is associated with a number of complications as

• decreased survival
• metabolic abnormalities
  • high blood pressure
  • insulin resistance
  • dyslipidemia
• pulmonary abnormalities
• arthritis
• urinary incontinence
• cataracts
• cancer

Moderate weight loss in conjunction with physical activity improves physical function and health-related quality of life in obese older persons.

Physical activity and cardiovascular health

A higher rate of cardiovascular events and a higher death rate have been observed in those individuals with low levels of physical fitness (Pate RR et al., 1995., US Public Health Service, Office of the Surgeon General, 1996). Even midlife increases in physical activity, through change in occupation or recreational activities, are associated with a decrease in mortality (Paffenbarger RS et al., 1993). Despite this evidence, however, the vast majority of adults remain effectively inactive.

According to AHA, a sedentary lifestyle is one of the major risk factors for cardiovascular diseases. Evidence from many scientific studies shows that regular exercise decreases the chance of having a heart attack or experiencing another cardiac event, such as a stroke, and reduces the possibility of needing a coronary revascularization procedure (bypass surgery or coronary angioplasty).

Benefits of regular exercise on cardiovascular risk factors include:

• Increase in exercise tolerance
• Reduction in body weight
• Reduction in blood pressure
• Reduction in bad (LDL and total) cholesterol
• Increase in good (HDL) cholesterol
• Increase in insulin sensitivity

In addition, exercise training positively impacts the above risk factors even in patients older than 75 years (American Family Physician, 2005). There is also evidence that exercise training improves the capacity of the blood vessels to dilate in response to exercise or hormones, consistent with better vascular wall function and an improved ability to provide oxygen to the muscles during exercise. As one’s ability to transport and use oxygen improves, regular daily activities can be performed with less fatigue. This is particularly important for patients with cardiovascular disease, whose exercise capacity is typically lower than that of healthy individuals.

Patients with newly diagnosed heart disease who participate in an exercise program report a more positive outlook in terms of quality of life, such as more self-confidence, lower stress, and less anxiety. Importantly, researchers have found that for heart attack patients who participated in a formal exercise program, the death rate is reduced by 20% to 25%. This is strong evidence in support of physical activity for patients with heart disease (Circulation, 2003).

Physical activity and cancer

The International Agency for Research on Cancer estimates that 25% of cancer cases worldwide are caused by obesity and a sedentary lifestyle. These factors may increase cancer risk by several mechanisms such as increased estrogens and testosterone, hyperinsulinemia and insulin resistance, increased inflammation, and depressed immune function. Several studies have shown that physical activity and diet changes can alter biomarkers of cancer risk (Journal of Nutrition, 2007).

There is strong epidemiologic evidence for reduced risk of some cancers with increasing physical activity. The strongest evidence exists for colorectal and postmenopausal breast cancer, with possible associations for prostate, endometrial, and lung cancer (Friedenreich CM, Orenstein MR., 2002).

Types of physical activities

There are 4 main types of physical activities namely aerobic, muscle strengthening, bone strengthening, and stretching and balance activities. (Dairy Council of California, 2014) (National heart, blood and lung institute, 2011).

• Aerobic activities also called cardiovascular exercises help improve the condition of lungs and heart, increase stamina, improve blood circulation and burn body fat.

Such activities might include walking, jogging, bicycling, climbing stairs, walking on a treadmill, dancing, swimming or jumping rope. These types of activities help to raise your heart rate and increase your breathing for an extended period of time as well as decrease the blood pressure.

• Muscle strengthening increases the body metabolism by burning more calories after having stopped exercising. This is achieved by an increase in muscle mass.

Muscle-strengthening activities improve the strength, power, and endurance of muscles. Doing pushups and sit-ups, lifting weights, climbing stairs, and digging in the garden are some examples.

• Strength training helps make bones stronger, improves balance and increases muscle strength. All of this helps prevent osteoporosis and lowers the risk of hip fractures from falls. Strength training has also been shown to lessen arthritis pain.
• Stretching helps to ease movement, improve flexibility and prevent muscle strain and injury. Stretching also helps to warm up the body and prepare for exercise.
• Balance activities help you maintain posture and balance to keep from falling. This is particularly important for the elderly who are at risk for bone fractures.

Levels of physical activities by intensities

Intensity refers to the rate at which the activity is being performed or the magnitude of the effort required to perform an activity or exercise (WHO, 2014).

The levels of intensities of physical activities are usually expressed in METs, Metabolic Equivalents.

MET is the ratio of a person’s working metabolic rate relative to their resting metabolic rate.

One MET is defined as the energy cost of sitting quietly and is equivalent to a caloric consumption of 1kcal/kg/hour. It is estimated that compared with sitting quietly, a person’s caloric consumption is three to six times higher when being moderately active (3-6 METs) and more than six times higher when being vigorously active (>6 METs).

One limitation to this way of measuring exercise intensity is that it does not consider the fact that some people have a higher level of fitness than others. Thus, walking at 3 to 4 miles-per-hour is considered to require 4 METs and to be a moderate-intensity activity, regardless of who is doing the activity whether a young marathon runner or a 90-year-old adult.

• Light-intensity activities require the least amount of effort, compared to moderate and vigorous activities. Light intensity activity is related to energy expenditure of less than 3 METs. It does not increase the heart rate.
• Moderate-intensity physical activity raises the heart rate, breathing rate and body temperature. During such type of activity, one can talk but not sing. The caloric consumption is from 3 to 6 METS.
• Vigorous intensity physical activity causes the greatest amount of oxygen consumption. It burns more than 6 METS. A person cannot utter more than a few words without gasping for breath.

Examples of physical activities based on intensity

Source: U.S. Department of Health and Human Services. (1999). Promoting physical activity. Champaign, IL: Human Kinetics.