Not so long ago, lifting weights was limited to athletes and bodybuilders. Developing physical strength was not something that we, the general population, were supposed to be bothered about. Keeping our bodyweight within a certain range and performing plenty of aerobic exercise is what was recommended to maintain optimal health.
More recently however, scientists have identified muscular strength as one of the strongest predictors of mortality available, as well as the dramatic effects of the age-related decline in muscle mass. Inactive adults have been shown to experience a 3-8% loss in muscle mass each decade. This decline is even more profound after the age of 50, when muscle loss occurs at a rate of 5-10% each decade. This is a huge problem for public health because skeletal muscle mass has a very strong influence on many conditions, such as obesity, type 2 diabetes, osteoporosis and heart disease.
I have built a business with a primary objective of making people stronger. As a by-product of this strength training, my clients improve pretty much all markers of good health. They lose body fat, improve insulin sensitivity, improve flexibility, reduce joint pain and improve their ability to function in everyday life.
Looking first at obesity, the largest component (under normal circumstances) of energy expenditure is resting metabolic rate. Resting metabolic rate is elevated in both the short term as a result of a weight training session (more so than traditional aerobic exercise!) and in the long term by an increase in muscle mass (or a reduction in the age-related decline). The likelihood of the food you eat being stored as fat is also massively reduced if you are regularly stimulating your muscle fibres at high intensities. This effect is even more profound if you eat a high protein diet.
Increasing muscle mass and making the tissue more active through weight training is also an extremely effective way to improve insulin sensitivity and prevent type 2 diabetes, an increasingly prevalent condition. Weight training also provides the mechanical forces on bones required for modelling and remodelling, aiding the maintenance of adequate bone strength and density as we age. Interestingly, the largest loads experienced by bones come from muscle contractions (tendons pulling on bone) rather than direct external forces (e.g. landing forces), emphasising the necessity of strength and muscle mass in the prevention of osteoporosis.
In addition to the specific contribution of weight training and muscle mass to the prevention of certain conditions, there is a more general requirement for muscle mass in coping with immediate illness and trauma. When the body is in a stressed state, such as following an injury or fighting an infection or cancer, there is an increase in the liver's production of proteins required for immune function and wound healing. The building blocks for these proteins (amino acids) are the same as those which make up skeletal muscle. In severe cases, the requirement for these building blocks massively exceeds the rate at which we consume them in our diets; therefore we begin to breakdown muscle tissue to fulfil the requirement. So if there is already a shortage of muscle mass, as there is in most sedentary individuals, the chances of being able to fully recover from serious illness or injury is massively reduced.
The take-home message is that weight training should not be viewed with apprehension by the general public, especially women and the elderly. Instead it should be acknowledged and utilised as the exceptional tool which it is in the fight against disease. In fact, I believe that developing physical strength and lean body mass should be the primary objective of any fitness regimen.