Part 1: Carbohydrate Dynamics - Moderate/prolonged exercsie

Glycogen stored in active muscles supplies almost all of the energy from resting to moderate exercise. In the first 20 minutes, liver and muscle glycogen supply between 40-50% of the energy requirement, with the remainder provided by fat burning and a little protein.

With time the muscle glycogen depletes and the blood glucose is increasingly utilized. Fat catabolism is also increasingly becomes a major energy supplier. Fatigue occurs when liver and muscle glycogen are depleted. This occurs despite enough oxygen supply and abundant energy from stored fat. The athlete may feel that he has “hit the wall”.

Fat contributes about 50% of the energy requirements during light and moderate exercise. Stored intramuscular fat and fat from fat cells becomes important during prolonged exercise. In this situation, the free fatty acids supply more than 80% of the exercise energy requirements.

A carbohydrate-deficient diet quickly depletes muscle and liver glycogen. This affects both all-out exercise capacity and the capacity to sustain high-intensity endurance exercise.

Individuals who train intensely should consume between 60 and 70% of their calories as carbohydrate predominately in unrefined form (8-10g per kg of body mass).

For the ordinary person just eat a normal balanced diet. To lose weight here are some tips:

To burn fat and lose weight, aerobic exercise is advocated. However, it must be of moderate intensity. When you exercise too hard or become breathless while exercising, the energy, which feeds your movement, is drawn from glycogen in your liver and muscles, not your fat stores.

You do not start to burn fat as soon as you begin your work out. Getting your body to burn fat instead of glycogen depends on complex hormonal responses (adrenal hormones and insulin) to trigger your fat cells to release triglycerides into the blood. The first 20 minutes of exercise the body burns sugar from the glycogen stores. The next 10 minutes it is a mixture of sugar and fats. Only after 30 minutes does the body burns proportionately more fat (50 percent from fat). The key about fat burning is to exercise not hard but long.

Studies in exercise physiology show that the minimal aerobic threshold to shed fat demands continuous movements of at least 30 minutes duration carried out at least 3 times a week. It has to be continuous and should you stop and restart workout after 20 minutes of exercise, the hormonal shift has reverted to burning sugar again. For beginners, you may find that your muscles may not sustain exercise for 30 minutes. It is okay as it may take several weeks to build up your muscular strength first.

SLOW DOWN.

Many so-called instructors advocate a training heart rate of 60-70 percent of the maximal heart rate (220 minus your age). However, at that kind of rate the unfit majority will reach their anaerobic threshold, and the body will burn mostly protein and sugar. That is why you see so many overweight women in aerobic classes and overweight men jogging in the park, panting like mad.

In fact, the optimal intensity of exercise for fat burning is far lower at 45-55 percent of your maximal heart rate. A daily walk of at least 30 minutes will burn far more fat than killing yourself at the gym.

Body fat is interesting stuff. It is very caloric dense. This means that it needs a lot of oxygen to be metabolized – broken down – so that it can be put into the bloodstream and used as energy. If your workout is too intense, the body will not be supplied with enough oxygen and switch to other tissue for energy. In effect it will stop burning your stored fat and increase its burning of protein and glucose, for these tissues require less oxygen to burn. Exercise too vigorously, say running or sprinting, and your body never gets enough oxygen to burn fat efficiently. For, as the intensity of your exercise increases, the amount of oxygen available decreases. When this happens, your body has to look for more and more sugar and protein to maintain the effort.

Build-up gradually

Initially you can start by walking 15 minutes, 3 times a week, and then build up to 45 minutes more intense brisk-walking at least 3 times a week, if not all days.

You should progress from light level of exercise initially if you are unfit or heavily overweight. Each level of intensity and duration should be maintained for at least 1-2 weeks. Please avoid injury. Progressing too rapidly will result in muscle soreness, fatigue, increased cardiac risk and eventually decreased motivation. Each exercise period should include warm-up and cool-down periods.

Light:
Slow walking (15 min/km, or 4 km/hr), tai chi, house cleaning, and golf (no buggy)

Moderate:
Brisk-walking (10 min/km, or 6 km/hr), active gardening, cycling (2.5 min/km, or 24 km/hr), badminton, swimming and aerobic exercise/dancing

High:
Jogging (6 min/km, or 10 km/hr), walking with upload hill, basketball, climbing and football.