Quick questions on Nutrition, hydration, supplementation and sleep for performance: HSC Health and Movement Science Focus Area 2

The dominant fuel for moderate-to-high-intensity exercise; refills muscle glycogen between sessions. Recommendations from groups such as the Australian Institute of Sport (AIS) and the International Olympic Committee position statement scale CHO intake to training load:

For long endurance events (typically over ~90 minutes), athletes deliberately maximise muscle glycogen in the 24-48 hours before competition by raising CHO availability (often to ~8-12 g/kg/day) while tapering training. Fuller glycogen stores delay the point at which the athlete "hits the wall", extending the time they can sustain race pace.

GI ranks how quickly a carbohydrate food raises blood glucose. High-GI foods (sports drinks, gels, white rice) cause a fast rise and are ideal for rapid refuelling during and immediately after exercise. Lower-GI foods (oats, wholegrains, legumes) give a slower, more sustained glucose release and suit a pre-event meal eaten a few hours out.

Supports recovery, repair and synthesis of new muscle protein. Commonly cited ranges in the strength and endurance literature sit around 1.2-2.0 g/kg/day for endurance athletes and 1.6-2.2 g/kg/day for strength and power athletes. Spreading intake across 4-5 meals of ~0.3 g/kg of high-quality protein each is more effective for muscle protein synthesis than a single large dose.

Provides essential fatty acids, fat-soluble vitamins and the dominant fuel for low-intensity work. Generally the residual macronutrient after CHO and protein targets are met, typically ~20-35 percent of total energy.

Iron (especially in female endurance athletes), calcium and vitamin D (bone health), B vitamins (energy metabolism) are common areas of concern. Deficiency screening with a sports physician is preferable to blanket supplementation.

Aim to start exercise euhydrated. Practical approach: ~5-10 mL/kg in the 2-4 hours pre-exercise; pale-yellow urine as a rough indicator.

Replace ~125-150 percent of body-mass loss (i.e. ~1.25-1.5 L per kg lost) over the hours after exercise, with sodium to retain the fluid. A quick check: weigh before and after; the body-mass change is mostly fluid.

A fluid deficit of even ~2 percent of body mass raises heart rate at a set pace, raises core temperature and perceived effort, and impairs both endurance and skill/decision performance. Early signs include dark urine, thirst and a larger-than-expected body-mass drop.

Drinking large volumes of plain water without sodium during long events can cause exercise-associated hyponatraemia (dangerously diluted blood sodium) - a risk of over-hydration that can be more dangerous than mild dehydration. Sodium intake matters in long-duration / hot conditions, and athletes should generally drink to thirst rather than force large fixed volumes.

~7-9 hours per night.

Often need toward the upper end and beyond; sleep is when much of the recovery (growth hormone release, muscle protein synthesis, central nervous system recovery, memory consolidation) occurs.

A regular sleep-wake schedule (similar bedtime and wake time most days) supports circadian rhythm and reduces sleep debt across a week.

Adding 1-2 hours per night (or a 20-90 min afternoon nap) can improve reaction time, mood and some performance measures in athletes who are sleep-restricted.

Cool dark room, limit screens and caffeine close to bedtime, consistent routine. Travel, late evening competition and early morning training all challenge sleep and need to be planned for.