The strength of muscles all over the body is referred to as muscular. In physiological terms, strength can be defined as the maximum force that can be exerted in a single voluntary muscular contraction.
The main way to develop muscular fitness is by overloading the muscles and then tiring them out with repeated movements known as ‘reps’. This overloading can be achieved in a variety of ways: from lifting weights to providing resistance for the muscles to push against. When the muscles recover from a training session, they are stronger and can work for longer.
Muscular fitness training is usually anaerobic, which means that, in contrast to aerobic exercise, it does not use oxygen. It relies on burning carbohydrate, stored in the muscles in the form of glycogen. Whereas aerobic fuel (fat) provides a sustained ‘slow-burning’ source of energy, anaerobic fuel (glycogen) provides energy for more intense exercise, such as repeated press-ups, or explosive moves, such as lifting heavy weights or sprinting.
Stores of glycogen are replenished when you eat plenty of carbohydrates and take rest days between workouts. Anaerobic exercise can be done only for relatively short periods because it produces lactic acid, and a build-up of lactic acid in the exercising muscle causes fatigue and pain. A few minutes’ rest enables the lactic acid to be dispersed by the circulation. Exercise can then continue.
Muscles tend to work in pairs. In the thigh, for instance, the quadriceps muscle at the front straightens the knee, while the hamstring muscle at the back, bends it. To strengthen your legs you must work both muscle groups, otherwise your knees will come under unequal strain. Each part of the body needs to work against resistance – of your body weight, as in floor exercises, for example, or added weight, as when using free weights or fixed resistance machines in a gym.
Some women feel reticent about working on their muscles because they associate highly defined muscles with a masculine appearance. However, unlike men, women are unlikely to develop body-builder physiques because they do not have enough of the male hormone testosterone.
Benefits of muscular fitness
A very basic benefit of muscular fitness is having the strength to meet the demands of ordinary day-to-day activities such as climbing the stairs and carrying heavy objects. Many people enjoy having fit muscles because they feel strong and physically powerful. Fit, toned bodies are also usually considered to be more aesthetically pleasing than those with slack or untoned muscles.
One of the reasons people gain weight as they age is because they lose muscle and store fat – inactive people lose up to 20 per cent of their muscle between their thirtieth and seventieth birthdays. The more muscle you have, the higher your resting metabolic rate (the rate at which the body burns calories when not exercising) and so the more fat you burn. The more muscle and less fat you have, the higher your energy levels, the greater your strength and the more defined your body. Fit muscles not only make the body stronger, more powerful and less prone to fatigue; they also encourage good posture – backache is often caused by weak muscles in theand lower back. Attention to muscular fitness will help you to maintain mobility in later life and also to avoid the bone-weakening disorder osteoporosis.
On a basic level, skeletal muscles provide the vital forces that enable the body to move. They are usually attached to one end of a bone, stretching across a joint to another bone. Fit muscles protect bones and joints by cushioning them with strong elastic. Strengthening your muscles also makes it less likely that you will have an accident and break a bone if you fall.
How hard should you work?
Start with light weights and aim to do a set of 15-20 ‘reps’ (repetitions or lifts); then try to do two sets. This type of programme builds up your muscular endurance – the length of time your muscles can keep working. Once you have built up muscular endurance, you can start working on improving muscle strength.
For strength training, you need to use a weight that is heavy enough to tire the muscle within a set of 8-10 reps. As your muscles become fitter, take a rest period and repeat. Once you can do as many lifts as you could with a light weight, increase the weight and decrease the reps.
Floor exercises and other exercises that build muscular strength can be used in combination with. It usually takes approximately four to six weeks to see significant improvements in muscular strength and endurance.
Dangers of muscle strength training
The main danger of muscle strength training is that of damaging the muscles. It is very common to experience some degree of muscle soreness after a weight-training session. This is thought to be caused by microscopic tears in the muscle fibres and should be short-lived. More serious, however, are torn muscles and ligaments, which can cause acute pain and restrict movement. Incorrect posture during muscle fitness training can make people vulnerable to back injuries.