Tribulus and fenugreek are both promoted for raising testosterone. A 2025 review found no robust evidence for tribulus; in a 12-week trial of 95 men, fenugreek raised saliva testosterone versus placebo but plasma testosterone only versus baseline.

Randomised trials of the NAD+ precursors nicotinamide riboside and nicotinamide mononucleotide show they raise NAD+, and two described them as well tolerated. Effects on function were limited: some ventilatory-threshold gains in runners, nominal gait and grip changes, and no change in VO2max or body composition.

Quercetin, a plant flavonoid, is marketed for recovery. In 12 and 16 men from one laboratory, 1,000 mg a day for 14 days raised isometric strength 4.7% from baseline and reduced the loss of strength and muscle fibre conduction velocity after damaging eccentric exercise.

In a 12-week trial in resistance-trained men, 400 mg a day of oral ATP was linked to +55.3 kg total strength versus +22.4 kg with placebo. A pilot sharing several authors found raised post-exercise blood flow. Striking results, with no independent replication read.

In 16 recreationally active women, sodium bicarbonate before each interval session for 8 weeks produced larger gains in lactate threshold and time to fatigue than placebo, at the edge of significance (P = 0.05), while muscle buffer capacity improved in both groups with no difference between them. A 10-day progressive dosing regimen improved CrossFit-style performance, with no gastrointestinal side effects reported.

Most caffeine research uses 5–13 mg/kg. A review finds doses under 3 mg/kg (about 200 mg) can also be ergogenic with few side effects, and a cyclist trial found both 100 mg and 200 mg sped up a time trial, with 200 mg faster still.

In a small crossover trial, creatine improved bench press reps at 80% of 1RM while beetroot juice improved bar velocity and heart-rate responses. Other nitrate trials in resistance exercise found no performance gain over placebo.

Worried your coffee habit is affecting your thyroid? In US NHANES data, 2–4 cups of coffee a day were associated with lower TSH and no significant change in thyroid hormones, with no link to hyperthyroidism or hypothyroidism; in a metabolically unhealthy subgroup, caffeine's association with TSH varied by dose.

In first-year students at Norwegian elite-sport high schools, athletes used snus, cigarettes and alcohol less than controls, but competing in team sports was linked to snus use (odds ratio 2.8, 95% CI 1.6 to 4.7). Practitioners report oral nicotine spreading in elite sport despite no proven performance benefit.

In a placebo-controlled crossover trial, night-time melatonin did not change sleep, morning caffeine increased shuttle-run distance with or without melatonin, and the combination lowered muscle-damage and inflammation markers. Taken in the daytime, melatonin dulled alertness and memory without changing a 4-km time trial.

Adaptogens are sold as natural performance aids. In 57 men new to resistance training, ashwagandha added to bench press gains (46.0 kg vs 26.4 kg); in women footballers it improved perceived recovery, and a Rhodiola trial found its best results only alongside caffeine.

A 2017 review counted ten studies of nicotine or smokeless tobacco on strength, power and endurance: two ergogenic, one ergolytic, seven with no change. What that means, and what it does not.

Forgot your pre-workout? In six habitual caffeine users cycling to exhaustion, placebo performance was no different after 0, 2 or 4 days without caffeine, and in 12 trained male cyclists 3 mg/kg improved a time trial by 3.0% after a 4-day withdrawal and 3.6% without one.

Caffeine–taurine combinations are widely used in commercial sports products. In a 2026 meta-analysis of 11 generally small trials they were associated with better peak power and time to exhaustion, but the analysis could not separate taurine's effect from caffeine's; a 2021 review calls taurine-alone findings limited and varied.

No trial of chewing whole coffee beans was found. Caffeinated gum, dose for dose, matched instant coffee's blood caffeine profile in one study, and in resistance-trained men it improved 1RM, reps to failure, jump height, barbell velocity and power.

Shatavari is an Ayurvedic herb long used for women's health. In 18 recreationally trained men, 8 weeks of 500 mg a day with bench training increased 1RM 14.3% versus 7.8% with placebo; in 20 postmenopausal women, 6 weeks improved handgrip but not knee strength.

Ammonia inhalants are widely used in competition. A trial in 20 trained men found a rise in early rate of force development only; a 2023 review sees benefit only in repeated high-intensity bouts.

Ginseng is sold as a natural anabolic. In eight men, 20 g of ginseng extract after resistance exercise did not change testosterone, cortisol, growth hormone or IGF-1 over two hours; a preliminary, partially controlled study in 24 women found mixed salivary results.

Genetic tests promise to tell you if caffeine suits you. A 2023 meta-analysis of 13 studies found benefits for AA and AC genotypes and a decrement for CC, yet the genotype effect vanished without conflicted studies, and two trials found no interaction.

The first creatine trial in Alzheimer's disease was small and had no control group. Brain creatine rose, several cognitive scores and handgrip strength improved, and a 2022 review found evidence in neurodegenerative disease lacking.