Physical activity should be encouraged in patients with DM. Physical activity refers to any bodily movement produced by skeletal muscles that results in an expenditure of energy which can be a broad range of occupational, leisure and daily activities.82Physical activity is a very important component of intervention that helps prevent weight gain, enhances weight loss and it is very important for maintaining weight. Physical activity also has a positive impact on other health-related outcomes. Increased physical activity helps to maintain energy balance. Walking three miles a day helps in reducing excess calorie intake that otherwise would be associated with weight regain.73Consequently, physical activity is recommended as an intervention programme to prevent overweight and obesity in adults. The U.S. Department of Health and Human Services’ 2008 Physical Activity Guidelines for Americans has observed that physical activity equivalent to 180 to 270 minutes per week led to weight loss of 0.5 to 3.0 kg. The report also noted that in studies reporting a lack of a significant reduction in body weight, physical activity was consistently less than 150 minutes per week. The most recent position stand of the American College of Sports Medicine (ACSM) has demonstrated that physical activity of more than 150 minutes per week results in weight loss of two to three grams, with weight loss of 5-7.5 kg occurring when 225 to 420 minutes per week of physical activity is carried out respectively.83 Physical inactivity has profound negative effects on lipid metabolism, including increases in LDL cholesterol levels, but this can be prevented by modest regular exercise. In line with this, the American Heart Association and the American Diabetes Association recommend carrying out at least 150 minutes of moderate intensive aerobic activity per week.49Physical activities help in weight loss, glycaemic control, improved blood pressure, and lipid profile and insulin sensitivity. Regular physical activity prevents obesity by increasing expended energy.7In a
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randomized trial in Pittsburgh, United States, which was done to determine the effect of physical activity, there was modest weight loss in all treatment groups at six, twelve and eighteen months with no significant difference between groups. Waist circumference and body fat also decreased with no significant difference between groups. This shows that behavior change in physical activity can lead to weight loss in overweight adults.84This agrees with a randomized clinical trial where significant improvements in body weight were seen in 1.6% of the study participants for the combination group compared to control and resistance groups.43 Also, 4.4% of them had improvement in total body fat compared to control with significant improvements in cardio-respiratory fitness. This shows that a single, moderate intensity 30 minutes bout of aerobic or resistance exercise improves risk factors associated with cardiovascular disease in overweight and obese adults. It also supports that moderate intensity training over 12 weeks using a variety of training modalities has beneficial effects on CVD risk factors in overweight and obese individuals compared to individuals who do not exercise.43 The similarities may be because both were randomized trials with similar interventions on behaviours to achieve weight loss over a certain period of time.
Exercise refers to planned or structured physical activity which involves repetitive bodily movements performed in order to improve or maintain physical fitness.81Aerobic exercise being a low-cost, low-risk, non-pharmacological intervention is available to the vast majority of the general public and has been recommended for improving cardiovascular risk factors.84The overall beneficial effects of exercise in T2DM are well documented with regards to glucose control and multiple CVD risk factors as it improves and maintains cardio-respiratory fitness, muscular strength, endurance and body composition.43 Exercise has a favourable effect on cardiovascular risk factors with specific beneficial effects on the reduction of hypertension and
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hyperlipidaemia and should be a component of prevention advice in every patient encounter for patients with type 2 diabetes mellitus.43Lifestyle activity should be increased slowly in intensity and duration (by five minutes/session/week), starting from a low intensity exercise in sedentary subjects in order to avoid excessive fatigue, muscle pain, strains or injuries. When brisk walking is chosen as the preferred activity, patient should be instructed to add 500 steps at a three-day interval to a target value of 10,000-12,000 steps/day. Although aerobic exercise may be considered as the preferred activity, resistance exercise and strength training should also be considered as effective options according to individual preferences.69
Aerobic exercise is characterized by the execution of cyclic activity, carried out with large muscle groups contracting at mild to moderate intensities for a long period of time. An acute exercise session can lower clinical blood pressure during the post-exercise period in both hypertensive and normotensive subjects. The effect of aerobic exercise in reducing clinical blood pressure in hypertensive subjects is well proven and accepted.43 The American Heart Association and the American Diabetes Association (ADA) recommends carrying out at least 90 minutes of vigorous aerobic exercise per week.49One study done using aerobic exercise as a form of intervention showed a reduction in HbA1c and a statistically significant reduction of about 5%
for LDL-C, though there were no statistically significant improvements in TC, HDL-C and TGs for those group of patients.81The minimum amount of exercise needed to increase HDL cholesterol levels is 900 kcal of energy expenditure per week, or about 120 minutes of typical aerobic exercise.68 Published data have demonstrated that one positive effect of regular aerobic exercise is a rise in HDL cholesterol levels by an average of 1.9 to 2.5 mg/dl (0.05-0.06 mmol/L). Other effects include decreases in total cholesterol, LDL cholesterol and triglyceride levels by an average of 3.9, 3.9 and 7.1 mg/dl (0.10, 0.10, and 0.08 mmol/L) respectively. Also,
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in patients with cardiovascular disease who carried out aerobic exercise, HDL cholesterol levels increased by an average of 9% (3.7 mg/dl/0.10 mmol/L) and triglyceride levels decreased by 11% (19.3 mg/dl/0.22 mmol/L), suggesting greater benefits in this high-risk group.
Improvements in HDL cholesterol levels seem to be related more to the amount of activity than to the intensity of exercise or improvement in fitness.68
In a double-blind randomized clinical trial in Kashan, Iran where supervised aerobic and resistance training plus structured exercise counselling was given to patients with T2DM two times per week for 12 months,there was a significant improvement in lipid profile and blood pressure compared with the control group. It was also found that HbA1c, fasting blood glucose, LDL cholesterol and total cholesterol were significantly reduced while HDL cholesterol increased.85These findings therefore demonstrate a global improvement in cardiovascular risk factors and highlight the potential benefits of exercise for patients with type 2 diabetes mellitus.
It also supports the fact that aerobic exercise reduces LDL-C by 10-18%. Exercise affects platelets functions and oxidized LDL-C, and as a result leads to reduction in cardiovascular risk factors.35
In order to achieve glycaemic control, maintain weight and reduce the risk of CVD, at least 150 minutes of moderate-intensity aerobic physical activity per week or at least 90 minutes of vigorous aerobic exercise per week is recommended. Patients with diabetes should therefore be encouraged to perform 30 to 60 minutes of moderate intensity aerobic activity such as brisk walking on most days of the week. This can be supplemented with an increase in daily lifestyle activities like walking breaks during workday, gardening and household work.43