Several supplements have strong evidence for enhancing athletic performance, with creatine monohydrate being one of the most studied and safest. Creatine is stored as phosphocreatine in muscles and regenerates ATP during short, high-intensity efforts, increasing muscle creatine stores by 20–40%. The standard protocol is a loading phase of 20 g per day (split into 4 doses) for 5–7 days, followed by a maintenance dose of 3–5 g per day, though simply taking 3–5 g per day without loading saturates muscles in about 28 days. Decades of research show no adverse effects on kidney or liver function in healthy individuals at recommended doses.
Caffeine reduces perceived exertion, increases alertness, and enhances endurance performance by 3–5%, with an effective dose of 3–6 mg per kg of body weight taken 30–60 minutes before exercise. Beta-alanine is an amino acid that increases intramuscular carnosine levels, buffering hydrogen ions during high-intensity exercise and reducing fatigue during efforts lasting 1–4 minutes; a common dose is 3–6 g per day, with the harmless tingling sensation (paresthesia) being a known side effect. Citrulline malate increases nitric oxide production and arginine levels, improving blood flow and reducing fatigue, with a typical dose of 6–8 g taken 30–60 minutes pre-exercise. Dietary nitrate from beetroot juice is converted to nitric oxide, which improves blood flow, reduces the oxygen cost of exercise, and enhances muscle efficiency, with an effective dose of about 6–8 mmol of nitrate taken 2–3 hours pre-exercise. Other useful supplements include HMB (a metabolite of leucine most effective for untrained individuals or during caloric restriction at 3 g per day), sodium bicarbonate as an extracellular buffer for efforts lasting 1–7 minutes at 0.2–0.3 g per kg taken 60–90 minutes pre-exercise, glutamine to support immune function in heavily training athletes, collagen peptides with vitamin C to support tendon and ligament health, and tart cherry juice to reduce muscle soreness and improve sleep. Pre-workout supplements typically combine caffeine, beta-alanine, citrulline, creatine, and nitric oxide precursors.
Nutrient timing involves strategically consuming specific nutrients at specific times relative to exercise to optimize performance, recovery, and body composition. The pre-workout meal, eaten 2–4 hours before exercise, should contain moderate protein (20–40 g), complex carbohydrates for sustained energy, and low-to-moderate fat. The post-workout meal should include 20–40 g of protein to stimulate muscle protein synthesis and 0.8–1.2 g of carbohydrates per kg to replenish glycogen stores, generally within 2 hours after exercise. The so-called anabolic window — a supposed 30–60 minute post-exercise period of enhanced nutrient uptake — is now understood to be wider than originally thought, with total daily protein intake being more important than precise timing. Sleep is also a critical component of recovery, as growth hormone is primarily released during deep sleep, facilitating muscle repair; a casein protein shake before bed can provide sustained amino acids during sleep.