1.2.a. Diet and nutrition and their effect... Typeit

The greater competitiveness of modern-day sport, influenced by the increased incentives for winning, is a major contributor to athletes striving to attain any competitive edge that will give them an advantage over their competitors. This has led to the development and uptake of  aids in many sports, which include any method or substance that improves physical or mental performance. Many of the most commonly used nutritional aids are outlined below.

Dietary supplements

•  – Elevates the store of phosphocreatine (PC) in the muscle, as well as its rate of following high-intensity exercise. This extends the time at which the body can rely on ATP-PC as an energy source, attenuating fatigue during short-duration, high-intensity exercise. Track athletes performing distances from 100 m up to 400/800 m can benefit from this, allowing for a greater sprint finish and decreased reliance on the glycolytic energy system, thus attenuating the build-up of fatiguing by-products.
• Caffeine – Most commonly found in energy drinks and coffee, this can have multiple benefits across a variety of sports. Caffeine can lower the perceived effort of activity, allowing the performer to maintain exercise intensity for longer by resisting fatigue. It can also increase  levels, which would be useful in performing fine skills during gymnastic routines and focusing on targets in archery. Moreover, it has the potential to alter energy utilisation during exercise, resulting in a preferential use of fat metabolism at the same intensity that the performer would otherwise use glucose. This is useful for endurance and team sports, where performers attempt to spare muscle glycogen as depletion of these stores towards the latter stages of exercise becomes a limiting factor to performance. 
• Bicarbonate – Helps to buffer the effect of  by drawing it out of the muscle cell, reducing the sensations of fatigue created in the muscles. It is, therefore, a useful supplement for athletes whose activities that place a heavy demand on the glycolytic energy system, such as 400–1500 m runners.
• Nitrate – Increases the levels of nitric oxide in the body which promotes of capillaries and arterioles, allowing a greater amount of oxygen to be delivered to the working muscles. On this basis, it is a useful supplement for aerobic-based activities. 

Dietary strategies

There are many dietary strategies that can be manipulated to maximise preparedness for, performance in, and adaptation from exercise. These also fall into the nutritional aid category and include:

• Amount of food – Depending on the performer's goals, if they want to maintain energy balance they would attempt to match energy intake with energy
• Composition of meals – Where a bodybuilder would consume a greater percentage of to increase muscle mass, a marathon runner would consume a greater amount of carbohydrate to boost glycogen stores 
• Timing of meals – An athlete must consider a range of factors when choosing when they should eat. Exercising too soon after eating could lead to , and not eating soon enough after exercise could decrease the rate of glycogen restoration and muscle protein synthesis.
• Hydration – Replacing the amount of water and  lost through sweat, respiration and urination is important in preventing dehydration. Dehydration draws water from the blood plasma and causes it to thicken, reducing venous return and stoke volume during exercise. It is recommended for water intakes to be equivalent to 150% of the pre- to post-exercise change in body mass (assuming 1 kg = 1 L), including sodium to aid fluid retention.
• Carbohydrate loading – Aims to trick the body into sparing muscle glycogen during competition. A loading strategy would be to initially deplete the body of glycogen stores, then consume a low-carbohydrate,  diet over the next few days. Training intensity should be kept low, so as to promote fat metabolism. In the days prior to the event, carbohydrate intake should be severely elevated, replacing fat intake. This would attempt to trick the body into sparing glycogen during the endurance event, promoting a greater fat metabolism at the same intensity.