Interesting results have been reported by Cussler et al.73 in a randomised trial of 140 postmenopausal women participating in a multimodal exercise programme (high‐intensity resistance training and a weight‐bearing circuit of moderate‐impact activities including walking/jogging, skipping, hopping, and stair climbing/stepping with weighted vests). Bone density improvements at the femoral trochanter were significantly and linearly related to total weight lifted during the 12 months, and also total weight lifted in leg press, squat, and military press exercises, but not to the volume or quality of the non‐resistance training components of the programme. High‐intensity resistance training is also more beneficial than low‐intensity training for muscle strength gains and muscle hypertrophy, in addition to associated gait disorders, functional impairments, and disability, making it ideal as a multiple risk factor intervention strategy for injurious falls prevention in osteopenic women.
Exercise in the treatment of osteoporotic fracture
In older men and women who have already sustained an osteoporotic fracture, exercise is still extremely important to help recover function and prevent recurrent injurious falls. Progressive resistance training has been shown to be superior to standard physical therapy during the recovery from hip fracture in elderly patients.74 In addition, resistance training has been shown to be a potent treatment for depression in older adults75 and may thus substitute for antidepressant medications, which are known to increase the risk of falls and hip fracture.23 A combination of resistance training and balance training may offer the best approach to rehabilitation in this setting, as it optimally targets several of the remediable physiological risk factors for falls, fractures, and disability in this cohort.76 Additional studies are needed to define the effects of training in this clinical setting on bone density and strength itself and the optimal timing and duration of such interventions in the post‐fracture recovery period.
Role of exercise and physical activity in adipose tissue accretion and distribution
The rising epidemic of obesity is now recognised internationally in both younger and older cohorts and is projected, if it continues, to lead to significant changes in related diseases such as diabetes and also life expectancy. Prevention of excess adiposity is both protective and in some cases therapeutic for many common chronic diseases, offering significant risk reduction in the case of osteoarthritis; cardiovascular disease; gall bladder disease; type 2 diabetes; breast, colon, and endometrial cancer; hypertension; stroke; and vascular impotence, for example. Although generalised obesity is associated with excess mortality, cardiovascular disease, osteoarthritis, mobility impairment, and disability, it is predominantly excess visceral fat that is associated with the derangements of dyslipidaemia, elevated fibrinogen, hyperinsulinaemia, glucose intolerance or diabetes, vascular insulin resistance, hypertension, and cardiovascular disease known as metabolic syndrome or insulin resistance syndrome. Reductions in visceral fat have been shown to improve glucose tolerance and insulin sensitivity in those with and without diabetes, and changes in trunk fat correlate with improved glycaemic control in type 2 diabetes.77,78 Hence the potential for exercise to impact favourably on the accretion and distribution of adipose tissue, as reviewed below, has enormous significance in that it may reduce the burden of disease expressed in the ageing population.
Cross‐sectional studies of physical activity and fat mass
Numerous cross‐sectional analyses have confirmed an inverse relationship between physical activity and abdominal fat. Master athletes compared with age‐ and BMI‐matched controls have lower waist circumference, and physically active women have lower waist‐to‐hip ratios than inactive women. It has been determined that the higher the intensity of activity independent of energy expenditure, the lower are the abdominal fat estimates for men and women. In a study of monozygotic and dizygotic female twins, physical activity was the strongest predictor of central obesity after controlling for genetic and environmental factors, and this persisted for those with a genetic predisposition to obesity.
Experimental studies of the influence of physical activity on abdominal fat
In the last few years, there has been accumulating evidence from well‐designed studies supporting the benefit of physical activity in reducing total abdominal fat. There is no evidence that age limits abdominal fat loss secondary to exercise. Most studies have included middle‐aged to older populations who have a higher accumulation of abdominal and visceral fat than younger adults. They are more likely to demonstrate a greater magnitude of change than subjects with lower abdominal fat mass at baseline.79 Furthermore, the potential for physical activity to attenuate the gain in visceral fat is evident in the obese as early as childhood.
Decreases in both total adipose tissue accumulation and its abdominal (visceral) deposition are achievable by both aerobic and resistive training, with significant changes in total body fat usually only in conjunction with an energy‐restricted diet or very large volumes of exercise (7 hours per week). Preferential visceral fat mobilisation is often seen in response to exercise and dietary intervention, which means that small amounts of total body weight or fat mass (5%) may be associated with substantial changes in visceral fat (25% or more), with important metabolic implications for the prevention or treatment of insulin resistance syndrome.80
Exercise and diet in combination are the most effective non‐surgical treatment for obesity, and this approach is uniformly advocated by international consensus panels. The advantages of adding exercise to diet alone include greater weight loss, preservation of fat‐free mass and resting metabolic rate, improved fitness levels, correction of metabolic abnormalities associated with visceral obesity, and better long‐term adherence to dietary modifications, producing sustained weight maintenance. Therefore, robust exercise plus diet appear to represent an optimal evidence‐based treatment for obesity.
Relationship between exercise intensity and changes in body fat
In general, weight loss parallels energy expenditure via exercise, whether achieved by greater volumes, intensities, or durations of the exercise prescription. There is no evidence yet from well‐designed studies that low‐intensity exercise is effective for reducing abdominal fat. Most robustly designed studies have used moderate‐ to high‐intensity aerobic interventions. An overall higher‐intensity stimulus can be delivered via intermittent intensities with resistance or interval training, a prescription that may be effective and more easily tolerated by ‘at‐risk’ populations than sustained, moderate, or intense exercise due to obesity‐related dyspnoea or osteoarthritis.
Relationship between exercise modality and changes in body fat
There is some evidence that aerobic training may be better than resistance training for reducing abdominal fat. However, at doses resulting in a sustained negative energy balance for several months, both resistance and aerobic exercise generally result in significant reductions in fat mass when sensitive measurement techniques (generally not anthropometrics) are used. Resistance exercise may be more suitable as a fat‐reduction strategy for older obese individuals who have cardiovascular disease, arthritis, osteoporosis, or mobility disorders, who may not tolerate moderate‐ to high‐intensity aerobic training or may need the added benefits of resistance training for maintenance of muscle and bone mass. Importantly, energy restriction results in significant losses of muscle and bone, and the addition of resistance training to hypocaloric dieting has been shown to prevent such adverse body composition changes,81 whereas aerobic exercise alone does not. Combined aerobic and resistance training has demonstrated a superior effect versus aerobic training alone on trunk fat in older men. More well‐designed studies are needed, particularly in overweight older adults, to explore the relative benefits
