Name: Mohamed Abdulwahab
Title: In the light of the energy systems used during prolonged endurance events, critically analyse the nutritional strategies that a marathon runner should adopt before and whilst running a marathon in temperate environmental conditions (16-18oC).
1.1 Energy intake:
1.2 Fluid intake:
1.3 Carbohydrate intake:
2. Building energy and fluid:
1. Before competition:
2. During competition:
3. Nutritional recommendation:
The term energy system refers to the body’s ability, or power, to do physical work. The energy system requires to do body work that takes several different forms: mechanical, electrical, light, radiant, and heat (Economos, 1993). Energy system is like matter, which can neither be created nor destroyed (Bortz, 1993). It can only be changed into another form; therefore energy is constant cycle in the body and environment (Nelson, 1993).
Potential energy is stored energy which is ready to be used. Kinetics energy is active energy which can be used to do work (Burke, 1991). Energy balance in a physical activity requires a base of sound nutrition to supply the substrate fuels, which along with oxygen (O2) and water (H2O) meet widely varying levels of energy demand for body action (Gollan, 1991).
Fuel sources are the basic energy nutrition in the diet, primarily carbohydrate and some fat (Read, 1991). Their metabolic products-glucose, glycogen, and fatty acids-provide ready fuel sourced for the chemical energy reactions within cells (Murray, 1998). The main energy compound of the body cells is needed during a marathon run is aerobic system (Horswill, 1998). It has rightly a form of energy currency of the cell.
A long-term energy system, when exercising more than 2 minutes is required O2 dependant, or aerobic energy system (Pate, 1992). A constant supply of O2 in the blood is necessary for continued exercise (Branch, 1992). Especially cells organelles, the mitochondria are located within each cell, produce large amounts of adenosine triphosphate (ATP) (Hargreaves, 1996). The ATP is produced mainly from glucose and fatty acids and supplies the continued energy needs of the body (Dillo, 1996).
When the fuel nutrition becomes depleted during exercise, as an energy demands increase the body burns blood glucose and muscle glycogen as well as reserves from fatty acids to provide energy (Angus, 1996). With prolonged exercise levels of these nutrition fail too low to sustain the body continued demands, fatigue followed and exhaustion threatens (Fabbriao, 1996).
A marathon runner, energy system is defined as aerobic capacity, which depends on the body’s ability to deliver and the use of O2 in sufficient quantities to meet the demands of increased level of exercise (Coyle, 1986). O2 uptake increases with exercise intensity until either the demand is net or the ability to supply it is exceeded (Hammert, 1986). The maximum rate that the body can take in O2, or aerobic capacity is called the Vo2max the maximum uptake volume of O2 (Ivy, 1986). This capacity determines the intensity and duration of exercise that an athlete can perform (Coyle, 1986).
A long-distance race requires the sustained production of high rates of energy production, with the typical contribution of aerobic energy system varying according to the duration of the race (Costill, 1985). Aerobic metabolism accounts for the greater majority of the energy cost of long-distance events, especially half-marathon and marathon races (William, 1996). The elite level of long-distance running, particularly in males, is dominated by African runners, are outstanding competitor in half-marathon and marathon events (Wilson, 1996).
1.1 Energy intake:
Endurance athletes are involved in events where there is...