Caffeine prolongs sleep latency, reduces total sleep time and efficiency; clinically meaningful disruption occurs with 400 mg within 8–12 h of bedtime.

Caffeine significantly improves reaction time (g=0.28) and accuracy (g=0.27) on attention tasks; dose ≥200 mg shows larger effects.

Strong evidence that 3–6 mg/kg caffeine improves endurance, strength, and power; benefits consistent but moderated by genetics and habituation.

Significant overall effect size (ES = 0.18, 95% CI 0.08–0.28); greatest benefit for exercise in 1–10 min duration window.

4–6 g/day for ≥4 weeks significantly augments muscle carnosine (intracellular pH buffer) and improves exercise lasting 1–4 min; no benefit for efforts <60 s.

Vitamin D insufficiency is prevalent among athletes, particularly indoor athletes and those in northern latitudes in winter. Insufficiency is associated with reduced muscle strength, power, and endurance; supplementation of 2,000–6,000 IU/day recommended to maintain 25(OH)D >40 ng/mL.

Vitamin D at 700–800 IU/day reduced hip fracture risk by 26% (RR 0.74) and any nonvertebral fracture by 23% (RR 0.77); no significant benefit was observed at 400 IU/day.

Vitamin D supplementation reduced risk of acute respiratory tract infection (adjusted OR 0.88, 95% CI 0.81–0.96); greatest benefit in those with baseline deficiency (<25 nmol/L) and those receiving daily or weekly dosing rather than bolus doses.

Consistent improvements in strength, power, and training volume; safe for long-term use (up to 30 g/day for 5 years studied). Loading optional; maintenance commonly 3–5 g/day.

Oral creatine may improve short-term memory and intelligence/reasoning in healthy individuals; effect on other cognitive domains unclear.

Omega-3 supplementation associated with reductions in cardiovascular events; benefit most consistent at higher EPA+DHA doses (≥2 g/day) and in high-risk populations.

Omega-3 PUFA supplementation produced a statistically significant reduction in DOMS (MD −0.93, 95% CI −1.44 to −0.42; p=0.0004) across 12 RCTs, though the effect size fell below the minimal clinically important difference of 1.4 on a 10-point VAS. Low-quality evidence overall.

High-dose omega-3 (≥2 g EPA+DHA/day) consistently reduces fasting triglycerides by 15–30% in adults with elevated baseline levels.

Retatrutide produced substantial mean body-weight reductions over 48 weeks (up to ~24% at highest dose), with larger losses at higher doses; GI adverse effects were common and dose-related.

The TRIUMPH phase 3 program (4 trials, >5800 participants) evaluates once-weekly subcutaneous retatrutide vs. placebo for weight management and obesity-related complications (OSA, OA, CVD). No primary efficacy results published as of early 2026; design and rationale published in 2025.