Before training
The point of a pre-training meal is to arrive with fuel available but without a full, still-digesting stomach. How much carbohydrate is available is the factor that most reliably affects the quality of hard or long sessions, and the professional-society position stands on carbohydrate for training and competition are built around matching intake to what the session demands, rather than to a fixed daily figure.
Protein before training adds to the day’s total and to the amino acids available around the session; the position stand on nutrient timing treats the window around training as much wider than it was once described.
During training
For most sessions under about an hour, water is enough and eating during exercise adds little. As sessions get longer and harder, taking in carbohydrate during exercise becomes a genuine performance factor, and the literature on carbohydrate for competition addresses that directly.
Caffeine is among the best-evidenced performance aids and has its own professional-society position stand.
Hydration and electrolytes
Fluid lost in sweat carries electrolytes with it, mainly sodium. Replacing the water alone during long or hot-weather work covers only half the loss. How much people sweat varies a lot between individuals and conditions, which is why generic fluid figures translate poorly, and why athletes are usually advised to work from their own change in body weight across a session.
After training: glycogen and repair
Nutrition after exercise does two jobs: refilling muscle glycogen, and supplying amino acids for repair and adaptation. The review on glycogen restoration looks at when taking protein together with carbohydrate changes how fast glycogen is restored — the effect is real when carbohydrate intake is on the low side, and fades when it is already adequate.
When a second session follows within hours, refilling quickly is time-critical. When the next session is a day away, total daily intake does most of the work.
Supplements with an evidence base
Creatine and caffeine are the rare exceptions with professional-society position stands reviewing both how well they work and their long-term safety. Those conclusions are reported here; no protocol is.
The low-carbohydrate debate
The carbohydrate-availability position is the mainstream one, and it is contested. A formal published debate in a nutrition journal makes the case that low-carbohydrate diets do not hold back endurance performance. The dissenting side is cited in the research library alongside the position stands it disagrees with, because the question is genuinely open at the edges.
