Two very important determinants for athletic performance are training and genetic makeup. However, athletes need an optimal individualized diet to supply the energy needed to carry on with activities. A good diet can not substitute for either genetics or training, but can enhance and maximize athletic potential.

On average energy use is about 5 to 8 kcal/minute for a moderate activity. A small person may need around 1800 kcal/day while a large and muscular individual may need 4000 kcal/day. Energy required for training or competition has to be added to the basal energy just for normal activities. The first consideration, if an athlete experience fatigue daily, should be that consumes enough food.

To know if an individual is receiving enough energy from food, one step is to estimate the daily intake. A second step would be to estimate body fat percentage of the athlete’s body by using one of the following methods.

a) Bioelectrical impedance: Use of painless low energy electrical current to and from the body via electrode patches and wires.

b) Underwater weighing: Requires a trained technician and complete submersion in a water tank. This is the most accurate method.

c) Skin fold thickness: A method most widely used to measure fat tissue percentage.
Calipers are used to measure fat directly under the skin in several sites.

When tests for body fat composition shows too much body fat an athlete must lower food intake, the equivalent to about 200 to 500 kcal/day, until the desirable fat percentage is reached. When there is need for weight gains an athlete must increase food intake, the equivalent of about 500 to 700 kcal/day, until the desired weight is achieved. Food intake need to be a combination of carbohydrates, fat and protein while maintaining exercise to ensure that weight gain is mostly lean tissue not added fat.

Some athletes often lose weight so they can compete in lower weight class to gain advantage over a smaller stature opponent. They achieve a weigh loss of up to 10 kg a day, mostly water, by sitting in a sauna and/or taking diuretic drugs. However, losses of as little as 2% of body weight by dehydration adversely affect endurance performance. A continues pattern of loss and gain in weight of more than 5% of body weight by dehydration increases the risk of kidney malfunction, heat related illness and even death.

body weight, body fat composition

Health or Wellness is not merely the absence of disease but the sum or collection of the physical, mental and social well-being and the meaning we give to life.

Utilization of carbohydrates as fuels during exercise depends primarily on the intensity and duration of the activity. Generally, carbohydrate use increases with increasing intensity and falls with increasing duration of an exercise activity. Glucose is an important carbohydrate in human biology. Cells uses it as fuel-source of energy. The breakdown of food molecules in glucose and other simple sugars is what fuels the reactions which take place inside of our bodies.

Glucose breaks down during glycolysis; production of ATP (adenosine triphosphate) through the degradation of glucose in the absence of oxygen. The process of glycolysis yields a small amount of ATP. During glycolysis the three carbon compound pyruvate is produced. When oxygen is present more ATP is produced from further metabolism of pyruvate. During intense exercise, physical activity or when supply of oxygen in muscle is limited pyruvate produced from glycolysis accumulates in the muscle and is converted into lactate.

On glycolysis one glucose can yield 2 ATP and can re-supply depleted ATP in muscle activity. Most of the energy provided for exercise or physical activity, after it started, for about 30 seconds to 2 minutes derives from glycolysis. Fat utilization does not occur fast enough for ATP demands to be met. If the energy source for exercise or physical activity was only fat we wouldn’t be in a position to carry out activities more intense than a fast walk.

While the anaerobic pathway - glucose provide a major energy fuel for short term, high intensity exercise there are some major disadvantages: Only 5% of the available energy from glucose is released during glycolysis thus ATP production can not be sustained for long. Accumulation of lactate increases acidity of muscle cells that in turn inhibits the activity of key enzymes in glycolysis and production of ATP soon slows and muscle fatigue sets in.

glycolysis, exercise and glycolysis

Health or Wellness is not merely the absence of disease but the sum or collection of the physical, mental and social well-being and the meaning we give to life.

When physical activity or exercise is of low or moderate intensity and muscles are in an aerobic state (plenty of oxygen available), most of the pyruvate produced during glycolysis is further metabolized to turn more energy and finally carbon dioxide and water.

Almost 95% of the aerobically produced energy fuel, adenosine triphosphate (ATP), from the complete metabolism of glucose, it takes place in the mitochondria. Several health supplements such as minerals and some of the B vitamins are important key factors in the production of energy of both anaerobic and aerobic pathways.

Aerobic cellular respiration includes those areas of the metabolic pathway that are oxygen dependent. The aerobic pathway produces ATP more slowly than the anaerobic pathway. However, aerobically released energy production is a lot higher and can be sustained for hours making it an important energy contribution to physical activity and/or sports. Its contribution lasts more than 2 minutes and up to 4 or 5 hours.

The aerobic pathway uses carbohydrates and fatty acids as fuel so that it represents an enormous potential source of energy. For athletes, the aerobic system is the main provider of ATP in events lasting more than 3 minutes.

Glycogen is the ort term storage form of glucose in the liver and muscles about 100g and 300g respectively. Glycogen is the primary source of glucose for the production of ATP for muscles during intense activities that last about 2 hours or so. Glycogen is broken down into a form of glucose that becomes available to both aerobic and anaerobic pathways. Depletion of glycogen in the muscles contributes to muscle fatigue while depletion in the liver creates blood glucose fall.

When depletion of glycogen stores take place the maximum capacity that can be achieved by an athlete, while continue working, will be about 50% of maximum capacity and further exertion is hampered. When maximum volume of oxygen consumed per unit of time (VO2max) for longer than an hour consideration of increasing stored carbohydrates in the muscle is an appropriate decision.

Exercise durations longer than 30 minutes will require maintenance of blood glucose levels and therefore intake of carbohydrates in the order of 40 to 60 g/hour during strenuous endurance exercise. Maintaining blood sugar levels can spare glycogen in the muscles in search of the edge over the opponents in the finish line.

The intake of carbohydrates in short term events of 30 minutes exercise or so is not so important since the muscles during sort term exercise do not take up blood glucose due to the action of several hormones; Glycogen and epinephrine suppress the action of insulin to increase the uptake of glucose by the muscles. Carbohydrate intake during exercise is overall a very important source of energy fuel before and during prolonged, strenuous and continuous exercise and/or physical activity.

aerobic exercise, exercise, glucose

Health or Wellness is not merely the absence of disease but the sum or collection of the physical, mental and social well-being and the meaning we give to life.