Overweight and obesity are the leading causes of insulin resistance, which is why doctors commonly advise patients to lose weight through diet, lifestyle modification, and exercise. However, unlike diets where there is an abundance of programmes and regiments to follow—exercise lacks detail and specificity in its guidelines.
In general, the effectiveness of exercise against insulin resistance is based on the increase in physical activity. In fact, physical activity has been increasingly popular as a method to improve insulin sensitivity. A study that found a drastic reduction in physical activity for as short as two weeks can reduce insulin sensitivity.
Aerobic exercise forces the lungs to pump oxygenated blood to supply oxygen to the working muscle in a period of time. Options for aerobic exercise include swimming, jogging, walking, rowing and aerobic dancing.
Although there are studies suggesting that aerobic exercise modulates insulin sensitivity by reducing adipocyte, there is research that has proven otherwise. For example, a study of middle-aged adults with insulin resistance showed that 30 minutes of moderate walking for three to seven days for six months is able to reverse their insulin resistance even without changing the diet or losing any body weight.
Aerobic exercise also proves to be effective in type 2 diabetic postmenopausal women. A study showed that their insulin sensitivity was improved by 20% by doing 45 to 60 minutes of aerobic exercise three times a week for 16 weeks. This is to be noted as previous studies had shown that ageing and menopause are associated with insulin resistance.
Aerobic exercise has been proven to immediately improve insulin sensitivity within as short as three to five days. Research conducted among sedentary women showed that their insulin sensitivity improved by 58% after a week of one hour of aerobic exercise daily.
Hence, it is important for the doctor to advise the patient to keep doing aerobic exercise regardless of whether there are changes in body weight or body composition.
Resistance exercise forces the skeletal muscle to contract. It may include weightlifting, bodyweight exercise, and resistance band exercise. Some researchers suggest that resistance training modulates insulin sensitivity similar to aerobic exercise, which is by reducing adipocyte.
At the same time, there are others that suggest resistance training works through building more muscle mass, thus improving the glucose uptake mechanism and insulin sensitivity to support the muscles. Research also showed that a single session of resistance exercise could improve whole body insulin sensitivity for up to 24 hours after in healthy men.
A study showed that previously inactive people with type 2 diabetes improved their insulin sensitivity by 48% within four to six weeks of moderate resistance exercise, even without significant changes in muscle mass or body fat.
Also, twice a week of resistance exercise for four months was proved to be enough to improved insulin sensitivity. Thus, a doctor may suggest this exercise in patients with a hectic schedule.
Combination of both exercises
In the meantime, another study found that adding resistance training on top of aerobic exercise greatly improved insulin sensitivity compared to aerobic exercise alone. This study suggests that resistance training may able to complement aerobic exercise—and patients may be able to get the best of both, out of it.
Doctors should advise patients to choose an exercise that is easy to commit to, and fits into their lifestyle. Although the combination of both exercises is better, what is more important is to be physically active consistently, since insulin resistance returns to baseline after cessation of exercise. MIMS
Stair climbing associated with several health benefits
The link between sleep behaviour and diabetes
In conversation: Geriatrician Dr Nur Farhan on diabetes management in the elderly