Advice on feeding athletes has changed more often than almost any other area of preparation, and several confident recommendations have since been abandoned entirely.
Meat was once considered the source of strength
For a long period, athletes were advised to eat large quantities of meat on the reasoning that muscle is protein and must therefore be built from dietary protein directly.
Pre-competition meals of steak taken close to the event were standard in several sports, including well into the era of organised international competition.
The practice worked poorly, since a large protein and fat meal digests slowly and leaves an athlete competing while their body is still processing it.
Carbohydrate emerged as the limiting fuel
Work on muscle fuel stores established that carbohydrate held in muscle is the main fuel for sustained hard exercise and that depletion coincides with the point of collapse in endurance events.
That produced carbohydrate loading, in which athletes deliberately deplete and then over-supply stores in the days before a long event.
Early protocols were severe, involving a depletion phase that left athletes exhausted, and were later simplified once it became clear the depletion step added little.
Fluid advice swung between extremes
Athletes were once discouraged from drinking during competition, then advised to drink as much as possible, and both positions caused problems.
Excessive intake dilutes blood sodium and can be dangerous, while inadequate intake impairs performance and heat tolerance, so the guidance settled on drinking according to thirst and sweat losses.
Because sweat rates vary enormously between individuals and conditions, this is now treated as a personal calculation rather than a universal recommendation.
Timing became the focus
Attention shifted from what athletes eat in total towards when they eat it, particularly around training sessions and between events on the same day.
Practical questions dominate: how quickly stores can be replenished between rounds, and what can be consumed during exercise without causing digestive trouble.
Tolerance for eating and drinking while working is itself trainable, which is why endurance athletes rehearse their race fuelling rather than adopting it on the day.
Individual variation ended universal prescriptions
Athletes differ in digestion, sweat composition, food preferences and how they respond to eating close to competition, and these differences are large enough to matter.
Current practice therefore concentrates on establishing what works for a particular athlete through trial in training, rather than applying a standard plan.
Anyone with a medical condition or a restricted diet needs a qualified professional rather than general guidance, since the interactions involved are beyond what a coach can reasonably assess.
