Sports - Diet & Supplementation

Human performance, whether it’s elite or just recreational, is strongly influenced by what the person eats or drinks. Therefore it is essential to fuel the body according to its metabolic needs.  The human body must be supplied adequate energy in order to perform day-to-day functions such as breathing, growth and repair. As a person’s activity levels increases, naturally their energy requirements increase.

Fuel sourced during exercise
Energy sources include proteins, fats and carbohydrates. The source of fuel that your body chooses to use depends on the intensity and duration of the exercise, the fitness level of the individual, and their dietary intake.
For high intensity and short duration exercise, such as sprinting, only anabolically broken down glucose and glycogen are used. However if this intensity level continues, there is a risk that the muscles will run out of its stores of glycogen.

During more moderate forms of exercise such as cycling, jogging or recreational swimming, roughly only half of the energy used is taken from muscle stores of glycogen from aerobic breakdown, and the rest of the energy is obtained from glucose and fatty acids from the blood.

Lower levels of physical activity such as during walking is fueled entirely by the aerobic breakdown of fuels, so fat can be utilised for energy, and is the reason that walking is often the most effective form of exercise for individuals wanting to lose body fat. Additionally, the longer the duration of exercise, the more fat the body will use as fuel, however if there are no carbohydrates available to the body such as glucose in the blood or glycogen in the muscles, fat cannot be metabolised.

Diet & Exercise
If an individual consumes a high amount of carbohydrates, the body will use more glycogen as fuel during exercise. On the other hand, if an individual consumes a diet high in fat, then more fat will be broken down for fuel during exercise. Most individuals however, especially in the western world have more than adequate fat stores to supply them with energy for some time. Consuming a diet higher in saturated fat can also have other health implications, such as increasing the risk of heart disease.

Fluid & exercise
Fluid is essential during exercise because the body must maintain an adequate blood volume,  to ensure that sufficient amounts of blood are circulating throughout the body. Circulating blood during exercise helps to maintain body temperature and maximise physical performance. The human body is extremely efficient at regulating body temperature and maintaining fluid and electrolyte balance, however it is common sense that what fluid and electrolytes are lost during exercise, must be replaced. Research has shown that plain water following exercise may not be the best drink of choice because electrolytes that are lost in sweat are not replaced. In fact, water with some sodium, potassium and glucose is the most effective at replacing lost fluids and electrolytes following exercise.

Protein & Exercise
Protein is essential in the body for growth and repair. Protein requirements tend to increase slightly the higher endurance the exercise is.  An individual who enjoys walking for exercise usually will just need the recommended daily intake of protein in order to meet their requirements. It has been show recently that those who exercise at a higher intensity, such as endurance athletes may have a higher protein requirement. Bodybuilders, especially novice bodybuilders may have an even higher requirement for protein, however it is unnecessary to consume protein way beyond requirements as it may actually compromise their ability to train at optimum levels.
The requirement of protein for healthy adults, according to the Nutrient Reference Values, are between 10% and 25% of total energy intake from protein.

Creatine & Exercise
Creatine assists the cells in providing energy, so when stores are depleted, energy cannot be adequately supplied to the body. Creatine is broken down in the muscles to form creatinine and excreted by the kidneys. Because creatine can be found in quite high amounts in meat and fish products, vegetarians, especially vegetarian athletes can be at risk of an inadequate amount of creatine.
Supplementing with creatine can assist the cells to create energy which will significantly assist with exercise performance. However the body seems to have an upper limit of creatine stores, so for an individual with already high stores of creatine, supplementation would be of little benefit.