ENERGY SYSTEMS When the body starts to do physical activities a number of changes take place. The exact amount of change will depend on the intensity and duration of the activity. As mentioned in earlier topics, regular training will result in adaptation of our bodies. The type of training undertaken determines what adaptations or responses are effected. Most sports are a mixture of aerobic and anaerobic work. Training makes both energy systems better. However, the training is different for each. Aerobic respiration is the production of energy using oxygen: (C6H12O6 + O2-> CO2 + water +energy). Anaerobic respiration is the production of energy without using oxygen: C6O12O6-> Energy + lactic acid. Exercise will cause the brain to increase the number of brain signals to the heart. This will cause an increase in the heart rate. The heart rate shows how hard you are working and which energy system is being used. The fastest the heart can beat is called your maximum heart rate, and can be calculated using the formula: maximum heart rate = 220 minus your age. If the heart rate is about 60 per cent of your maximum heart rate, you are working aerobically. The actual rate is measured by taking the pulse. How fit an individual wants to be will depend on working within a range of heart rates, which is the target zones. Therefore, you must train above a minimum heart rate of 60 per cent of your maximum to gain fitness. Exercise below this will gain no aerobic benefits. This means, you must exercise below an upper limit. Once the heart rate rises above a certain point you are doing anaerobic work and lactic acid will build up and cause pain. The aerobic range should be anywhere between 70 per cent-85 per cent of the maximum heart rate. You must exercise below this point to gain aerobic benefits. This is called your aerobic training zone. The heart rates at the limits of the zone are called the training thresholds. The lower limit is the aerobic threshold. The upper limit is anaerobic threshold. An unfit person should be working at 60 per cent – 70 per cent of their maximum heart rate, a fitter person at 65-75 per cent, and a fit person at 75-85 per cent. For aerobic training, choose an activity which involves the large muscles of the body, e.g. walking, swimming, jogging, cycling etc. Work for at least 15 to 20 minutes per session at least three times per week. Work at least 60 per cent of the maximum heart rate within your aerobic training zone. Weeks of aerobic training must be done before anaerobic training. Working at, or above, 85 per cent of the maximum heart rate means you are working anaerobically. AEROBIC TRAINING EFFECTS OF – The heart grows larger, its walls gets thicker, blood volume increases. More capillaries grow, fat is burned more readily; lower resting heart rate and larger arteries, leading to lower blood pressure. – Increased fitness of lungs and respiratory system, leading to stronger rib muscles and diaphragm. Therefore the chest gets bigger during inhalation, the lungs expands further, facilitating more air and more oxygen is picked up, preventing easy tiring. – Training at high altitude (eg. in Mexico City) makes the aerobic changes described above happen very quickly and is good for anaerobic events (sprints, jumps, throws). Most training effects that take place in the muscles happen as a result of our muscles having to work without oxygen during anaerobic activities. Therefore, the actual development will include muscle hypertrophy. The muscles become larger as the individual muscle fibres grow thicker, fast-twitch muscle fibres increase in size and become more efficient in coping with lactic acid before becoming tired, the muscle cells store greater amount of ATP creatine phosphate and glycogen, and the chemical reaction in the muscles that produce energy increases in quantity, speed and efficiency. Weight training also causes muscle hypertrophy. Muscle strength increases when very heavy weight is lifted for few repetitions. Muscle power increases when heavy weight is lifted for a number of fast repetitions. Muscle endurance increases when light weights are lifted for many repetitions. Muscle Atrophy will occur when the muscles become inactive. Therefore, they become smaller and weaker. Muscle atrophy usually happens when the athlete is out of training as a result of injury. Be reminded that when lifting weights you should know your onerepetition maximum (1 RM) in order to guide the following: – Maximum strength – at least three sets of six reps at near maximum weight – Muscular power – at least three sets of 10-15, using 60-80 per cent of 1 RM – Muscular endurance – at least three sets of 20-30 reps using 40-60 per cent of 1 RM.