Endurance
Everything in the library studied for it, medical and holistic together. Within each kind, what was shown to help comes first, strongest evidence first. What was tested and not shown to help stays on the list.
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Medication8Hormone therapy1Peptides and SARMs1Supplements26Therapies1Practices10Daily life4Food and drink1Devices and wearables3
Medication
Preventing exercise-induced airway narrowing
Shown to protect against the drop in lung function after exercise, with about 18 percentage points less fall in FEV1 than placebo after a single dose.
The numbers and sources
- Effect
- A single dose of a short- or long-acting beta-agonist before exercise reduced the maximum fall in FEV1 against placebo (MD -17.67%, 95% CI -19.51% to -15.84%). Side effects did not differ from placebo [2]. In a label trial, 2 inhalations of albuterol about 30 minutes before exercise prevented exercise-induced bronchospasm more than placebo [1].
- Population
- 53 trials with 1,139 participants, 45 of single doses [2]; 24 adults with asthma [1].
- Sources
- [2], [1]
- Caveats
- The meta-analysis pooled short- and long-acting beta-agonists, and heterogeneity was high in children [2].
Exercise-induced airway narrowing
Shown to reduce the drop in lung function after exercise when taken 2 hours before, a 13% fall against 22% on placebo, with less protection at 24 hours.
Compared with placebo [1]
The numbers and sources
- Effect
- In one crossover trial, the mean maximum fall in FEV1 after exercise 2 hours after a 10 mg dose was 13% on montelukast and 22% on placebo (difference -9%, 95% CI -12 to -5). At 24 hours the falls were 10% and 14%. Some patients were protected at 8.5 and 24 hours and some were not [1].
- Population
- 160 people aged 15 and older with exercise-induced bronchoconstriction in three crossover trials, 47 in the trial reported [1].
- Sources
- [1]
- Caveats
- Label trials with single doses. The label reports the other two trials as similar [1].
Athletic performance
Shown to improve maximal and aerobic performance by a small amount in 15 small trials, with no change in anaerobic performance.
The numbers and sources
- Effect
- Glucocorticoids had a small effect on maximal physical performance against placebo (standardized difference 0.300, 95% CI 0.080 to 0.520). The effect was seen with oral dosing (0.361, 95% CI 0.124 to 0.598), with prolonged treatment (0.428, 95% CI 0.148 to 0.709) and for aerobic performance (0.371, 95% CI 0.173 to 0.569). Anaerobic performance and energy use during submaximal exercise did not change [16].
- Population
- 175 subjects in 15 randomized trials [16].
- Sources
- [16]
- Caveats
- Few participants, and two studies were at high risk of bias. The authors describe the estimates as uncertain [16].
Exercise in low oxygen or at altitude
Small trials found sildenafil raised exercise capacity only at very low oxygen, about 3,900 m and above, with no change at lower altitudes.
The numbers and sources
- Effect
- Results differ by trial. Breathing 10% oxygen at low altitude, sildenafil 50 mg raised maximum workload to 172.5 W against 130.6 W on placebo. At Mount Everest base camp it also raised maximum workload and lowered pulmonary artery pressure [3]. At a simulated 3,874 m, sildenafil cut 6 km time-trial time by 15%. Responders improved 39% and nonresponders 1.0% [4]. At simulated altitudes of about 2,100 m and 3,900 m, sildenafil 50 mg did not change peak power or 15 km time-trial times, though oxygen saturation was 3% higher at the higher altitude [5].
- Population
- 14 healthy mountaineers and trekkers [3]; 10 trained men [4]; 11 trained men and 10 trained women [5].
- Sources
- [3], [4], [5]
- Caveats
- Small crossover trials of single doses. The positive results came from very low oxygen levels (about 3,900 m and above). The authors of [5] state benefits are unlikely below 4,000 m.
Physical function in older adults
Small trials found mixed results: perindopril raised 6-minute walking distance by 31 m in one trial and did not change physical performance in another.
The numbers and sources
- Effect
- Over 20 weeks, 6-minute walking distance improved by 31.4 m more on perindopril than on placebo (95% CI 10.8 to 51.9) in older adults with mobility problems [18]. Over 12 months in older adults with sarcopenia, perindopril 4 mg did not change the short physical performance battery score (difference -0.1 points, 95% CI -1.2 to 1.0) or any secondary outcome [19].
- Population
- 130 adults aged 65 and older with functional impairment, 95 completing [18]; 145 adults aged 70 and older with sarcopenia [19].
- Sources
- [18], [19]
- Caveats
- Both trials tested perindopril. The sarcopenia trial recruited 145 of a planned 440 people, and adherence to perindopril was lower than to placebo [19].
Endurance exercise performance
Not shown to change endurance performance overall in 10 crossover trials, with small gains in time-to-exhaustion tests and when taken 45 to 60 minutes before exercise.
The numbers and sources
- Effect
- Pooling 10 randomized, double-blind crossover studies, endurance performance did not differ between paracetamol and placebo (Cohen's d 0.09, 95% CI -0.04 to 0.22). A small effect appeared in studies that gave it 45 to 60 minutes before exercise (d 0.14, 95% CI 0.07 to 0.21) and in time-to-exhaustion tests (d 0.19, 95% CI 0.06 to 0.33), and none in time trials (d 0.05, 95% CI -0.12 to 0.21) [16]. In one of the trials, 13 trained male cyclists finished a 10-mile time trial in 26 min 15 s on acetaminophen and 26 min 45 s on placebo, at a mean power of 265 against 255 W [17].
- Population
- 141 participants in 10 crossover studies [16]; 13 trained male cyclists [17].
- Sources
- [16], [17]
- Caveats
- Small studies of single doses. The subgroup results come from fewer studies than the main analysis [16].
Endurance performance in people without asthma
Not shown to improve aerobic performance, time trials, time to exhaustion or VO2 max in people without asthma, whatever the beta-agonist, dose or route.
Compared with placebo [10]
The numbers and sources
- Effect
- Beta-agonists did not change aerobic performance against placebo (SDM 0.051, 95% CI -0.020 to 0.122), with no heterogeneity (I² 0%). The result did not depend on drug type, dose, route, treatment length or athletic level [10].
- Population
- 47 randomized trials with about 680 participants without asthma [10].
- Sources
- [10]
- Caveats
- The analysis pooled several beta-agonists, not albuterol alone [10].
Physical function with exercise in older adults
Small trials found no gain in physical function with exercise, and one found smaller chair-stand gains on sirolimus than placebo in some analyses.
The numbers and sources
- Effect
- Over 13 weeks of home exercise, chair-stand repetitions rose in both groups. The difference was -2.13 repetitions (95% CI -4.61 to 0.34) for sirolimus 6 mg weekly against placebo. Complete-case (-2.46) and per-protocol (-3.44) analyses favored placebo significantly. Six-minute walk and grip strength also favored placebo, not significantly [3]. Handgrip and timed walk did not change on rapamycin 1 mg daily in the pilot [2].
- Population
- 40 sedentary adults aged 65 to 85, mean 72.2 [3]; 25 adults aged 70 to 95 [2].
- Sources
- [3], [2]
- Caveats
- Small exploratory trials. [3] was funded by Dr Brad Stanfield Ltd.
Hormone therapy
Strength and performance in healthy young athletes
Not shown to improve strength or exercise capacity in healthy young athletes, though lean body mass rose about 2 kg, mostly water. Sprint capacity rose slightly.
The numbers and sources
- Effect
- Lean body mass rose 2.1 kg (95% CI 1.3 to 2.9) against no growth hormone, but strength and exercise capacity did not appear to improve. Lactate during exercise was higher in 2 of 3 studies that measured it [2]. In recreational athletes given growth hormone for 8 weeks, sprint capacity rose 0.71 kJ (3.9%, 95% CI 0.0 to 7.7%), and 8.3% in men given testosterone as well. Endurance, strength and jump height did not change. The lean mass gain came from extracellular water, and the sprint gain was gone 6 weeks after stopping [3].
- Population
- 27 study samples with 303 treated participants aged 13 to 45, mean 27, mean treatment 20 days [2]; 96 recreational athletes, 63 men and 33 women [3].
- Sources
- [2], [3]
- Caveats
- Few studies measured performance, and trial doses may differ from covert use [2][3]. [3] was funded by the World Anti-Doping Agency.
Peptides and SARMs
Endurance and physical capacity
Not studied in people. MOTS-c raised physical performance in young, middle-aged and old mice, and a single dose lengthened running in untrained mice.
No study in people. This rests on animal studies.
The numbers and sources
- Effect
- MOTS-c treatment enhanced physical performance in young (2 months), middle-aged (12 months) and old (22 months) mice [12]. In untrained mice, a single dose raised total running time by 12% and distance by 15% in an exercise test [13]. In people, exercise raised the MOTS-c the body makes, in skeletal muscle and in the blood [12].
- Population
- Mice [12][13].
- Sources
- [12], [13]
- Caveats
- A rise in the body's own MOTS-c with exercise is not a test of taking it. No study giving MOTS-c to people was located, and FDA found no human exposure data by any route [3].
Supplements
High-intensity exercise lasting about 1 to 10 minutes
Shown to improve high-intensity exercise lasting about 1 to 10 minutes, by a median of about 3%, more in capacity tests than in time trials.
The numbers and sources
- Effect
- Across 40 placebo-controlled studies (1,461 participants), the overall effect size was 0.18 (95% CI 0.08 to 0.28). Within efforts of 0.5 to 10 minutes, exercise capacity tests improved more (0.50, 95% CI 0.25 to 0.75) than performance tests (0.11, 95% CI -0.20 to 0.42) [1]. An earlier meta-analysis found improvement in exercise of 60 to 240 seconds and over 240 seconds, none under 60 seconds, and a median 2.85% improvement after a median total of 179 g [2]. In 331 trained young men, the effect size for maximal efforts of 0.5 to 10 minutes was 0.39 (95% CI 0.09 to 0.69) [3].
- Population
- Healthy trained and untrained people; mostly men [1][2][3].
- Sources
- [1], [2], [3]
- Caveats
- Capacity tests (time to exhaustion) move more than performance tests (time trials), and performance is closer to competition [1]. Training status and total dose did not moderate the effect [1].
Endurance performance
Shown to improve endurance time-trial power by about 3% and completion time by about 2% in mostly young, trained men. Responses varied.
The numbers and sources
- Effect
- Across 46 placebo-controlled studies, caffeine improved time-trial mean power output by 3.03% (± 3.07, effect size 0.23) and completion time by 2.22% (± 2.59, effect size 0.41). Two studies reported slower times and five reported lower power on caffeine [1]. An umbrella review of 21 meta-analyses rated the endurance evidence moderate quality and found effects generally larger for aerobic than anaerobic exercise [2].
- Population
- Mostly young, trained men [1][2].
- Sources
- [1], [2], [3]
- Caveats
- Individual responses varied, including some slower performances. Most trials were in young men, and the umbrella review notes few data in women and older adults [2]. A 2026 meta-analysis of 19 trials in 235 women found a small cycling gain (SMD 0.21, 95% CI 0.11 to 0.29) [4]. In 17 studies, people given a placebo they believed was caffeine also performed better (d 0.49, 95% CI 0.28 to 0.69), on low-quality evidence [5]. Not every pooled estimate gave a definite direction across its 95% prediction interval [2]. Reference [3] is an ISSN position stand, a narrative consensus rather than a systematic review.
VO2 max and endurance
Shown to raise VO2 max and aerobic endurance in healthy adults and athletes, though results varied widely across small trials.
The numbers and sources
- Effect
- In 4 RCTs (142 participants), VO2 max rose by a mean 3.00 (95% CI 0.18 to 5.82) with high heterogeneity [10]. A Bayesian meta-analysis of 12 trials reported ashwagandha outperformed placebo on cardiorespiratory fitness [11]. A 2026 three-level meta-analysis of 13 trials found overall exercise performance improved (Hedges' g 0.47, 95% CI 0.25 to 0.69, I² 60%), most consistently for aerobic endurance (g 0.54, 95% CI 0.22 to 0.85) [12].
- Population
- Healthy adults and athletes [10][11]. 599 participants, mainly young adults or athletes [12].
- Sources
- [10], [11], [12]
- Caveats
- The 95% prediction interval for overall performance ran from -0.40 to 1.33, crossing zero [12]. The Bayesian abstract does not report effect sizes [11].
Endurance and exercise performance
Shown to improve endurance and time to exhaustion modestly in people, in small trials with low certainty.
The numbers and sources
- Effect
- Across 10 studies, taurine improved endurance performance by Hedges' g 0.40 (95% CI 0.12 to 0.67) and time to exhaustion by g 0.43 (95% CI 0.12 to 0.75). Dose and single versus repeated dosing did not change the effect [1]. A 2025 three-level meta-analysis of 23 trials of a single dose found g 0.25 (95% CI 0.10 to 0.39, I² 61%) across performance measures [2].
- Population
- 10 studies at 1 to 6 g a day, single doses up to 2 weeks [1]; 308 participants with 69 effect sizes [2].
- Sources
- [1], [2]
- Caveats
- GRADE certainty in [2] was low to very low. Several subgroup effects weakened after influential studies were removed, and prediction intervals often included no effect [2]. Both analyses pool small trials.
Energy and fatigue in healthy people
Small trials found a B complex lengthened time to exhaustion in 32 young adults, and a B, C and mineral product raised self-rated stamina in working men.
The numbers and sources
- Effect
- In a double-blind crossover trial, 28 days of a B1, B2, B6 and B12 product (Ex PLUS) raised running time to exhaustion 1.26-fold over placebo (p < 0.05) and lowered blood lactate and ammonia during and after exercise [10]. In 198 employed men given a B complex with vitamin C and minerals or placebo for 28 days, the supplement group rated themselves higher for physical stamina across assessments, and for concentration, mental stamina and alertness after a working day at some time points [11].
- Population
- 32 healthy adults aged 20 to 30, half women [10]. 198 men aged 30 to 55 in full-time work [11].
- Sources
- [10], [11]
- Caveats
- Two small trials of branded products. The second product also held vitamin C and minerals, so the B vitamins' share cannot be separated [11]. Ratings were self-reported, and effects in [11] appeared at some time points and not others.
Performance in women
Limited evidence: time to exhaustion improved in women, while other measures were imprecise, at very low certainty.
The numbers and sources
Stress and fitness
One small trial found better VO2 max, grip strength and mood scores than placebo in sedentary female students over 30 days.
The numbers and sources
- Effect
- In 78 female college students in India, 1,000 mg a day for 30 days improved heart rate, VO2 max, physical work capacity and right-hand grip strength against placebo, and anxiety, depression and well-being scores improved. The 500 mg dose differed from the 1,000 mg dose on VO2 max and work capacity [6].
- Population
- 78 sedentary female students, mean age 20.6 [6].
- Sources
- [6]
- Caveats
- One small trial. The abstract does not report effect sizes or funding.
Energy and endurance
Limited evidence: a review of Soviet-era studies reports more endurance and working capacity in healthy people and in animals, without figures in its summary.
The numbers and sources
- Effect
- The same review reports that Schisandra increased physical working capacity in animal studies, and in healthy people increased endurance, accuracy of movement, mental performance and working capacity [7]. In a 12-week trial in postmenopausal women, resting lactate, a fatigue-related marker, changed differently on Schisandra than on placebo [2].
- Population
- Animal studies and studies in healthy people in the former USSR, reviewed [7]. 45 postmenopausal women [2].
- Sources
- [7], [2]
- Caveats
- A narrative review of older studies, with no trial sizes or effect sizes in its abstract [7]. The lactate result was one measure among several in a small trial, and endurance itself was not tested [2].
Exercise performance and recovery
Mixed results: one review found better performance alongside training, while another found no gain in VO2 max, time trials or power. Reviews disagree on creatine kinase.
The numbers and sources
- Effect
- Across 24 RCTs, astaxanthin lowered creatine kinase (SMD -0.45, 95% CI -0.83 to -0.07) and lactate dehydrogenase (SMD -0.93, 95% CI -1.39 to -0.48). Malondialdehyde and IL-6 did not change. VO2 max, time-trial performance and maximal power did not improve [1]. An earlier meta-analysis found better physical performance when astaxanthin was combined with training (SMD 0.62, 95% CI 0.17 to 1.06) and higher fat oxidation [2]. A 2026 meta-analysis of 7 RCTs found lower advanced oxidation protein products after exercise (SMD -1.06, 95% CI -1.49 to -0.62, I² 48%), with no change in creatine kinase, malondialdehyde, superoxide dismutase or IL-6 [3].
- Population
- Healthy participants and athletes in 24 RCTs [1]; 346 healthy participants in 11 RCTs [2]; 188 participants in 7 RCTs [3].
- Sources
- [1], [2], [3]
- Caveats
- The first two reviews disagree on performance, and [1] and [3] disagree on creatine kinase. Heterogeneity for lactate dehydrogenase was substantial [1]. One funder of [1] is a university and company joint laboratory for skin nutrition and anti-aging.
VO2 max and endurance performance
Mixed results: some reviews found higher VO2 max in women and iron-deficient athletes, while others found no change in iron-deficient adults.
The numbers and sources
- Effect
- In women of reproductive age (22 trials), iron raised relative VO2 max by 2.35 mL/kg/min (95% CI 0.82 to 3.88) and lowered heart rate at set workloads by 4.05 beats per minute [6]. In iron-deficient non-anemic endurance athletes, VO2 max rose (g 0.610, 95% CI 0.399 to 0.821) [1]. In non-anemic iron-deficient adults, VO2 max did not change (SMD 0.11, 95% CI -0.15 to 0.37, 9 trials, 235 participants) [3]. In athletes, the VO2 max trend did not reach significance (SMD 0.49, 95% CI -0.09 to 1.07) [2].
- Population
- Women of reproductive age [6]; endurance athletes [1][2]; non-anemic iron-deficient adults [3].
- Sources
- [1], [2], [3], [6]
- Caveats
- The reviews disagree. Only 3 of 24 studies in [6] were at low risk of bias, and its abstract does not state participants' anemia or iron status.
Muscle and physical function
Mixed results: one review found no change in muscle mass, strength or gait speed in older adults, while others found better endurance or gait speed.
The numbers and sources
- Effect
- In adults with a mean age over 60, NMN did not change skeletal muscle index (MD -0.42, 95% CI -0.99 to 0.14), grip strength, gait speed (MD -0.01 m/s, 95% CI -0.08 to 0.06) or chair-stand time. Knee extension strength, SPPB scores and thigh muscle mass did not improve [4]. A network meta-analysis of NAD precursors reported higher endurance with NMN at medium dose (SMD 0.66, 95% CI 0.09 to 1.23) and high dose (SMD 1.02, 95% CI 0.43 to 1.60), with no change in strength [5]. One trial reported a longer six-minute walk on 300 to 900 mg a day than placebo [1]. A 2025 meta-analysis of 9 RCTs (412 middle-aged and older adults) found faster gait speed on NMN (SMD 0.34, 95% CI 0.03 to 0.66) and lower ALT (SMD -0.29, 95% CI -0.55 to -0.03) [6].
- Population
- Randomized trials in adults with mean ages of 60.9 to 83 years [4]; 27 studies with 1,599 adults across NR, NMN, NADH and nicotinamide [5]; 80 middle-aged adults [1]; 412 middle-aged and older adults [6].
- Sources
- [4], [5], [1], [6]
- Caveats
- The reviews disagree on endurance and on gait speed [4][5][6]. The pooled muscle analysis included 2 to 5 studies per measure [4]. The network analysis mixes precursors and populations [5].
Endurance performance
Mixed results: a review of 26 trials found better VO2 max and endurance in healthy young adults, and a later review of 9 trials found no VO2 max effect.
The numbers and sources
- Effect
- Across 26 RCTs (668 healthy participants, mean age 22), rhodiola improved VO2 max (11 studies, ES 0.32), time to exhaustion (7 studies, ES 0.38) and time trial performance (5 studies, ES -0.40). Creatine kinase (ES -0.84) and lactate fell, and IL-6 and CRP did not change. VO2 max gains were larger above 600 mg a day [4]. A systematic review of 10 papers reported less pain and muscle damage after training and improved explosive power [5]. A 2026 meta-analysis of 9 RCTs (424 healthy adults) found no significant effect on VO2 max (95% CI -0.91 to 2.99) [6].
- Population
- Healthy young adults, mean intervention 33 days [4]; exercise studies [5]; healthy adults [6].
- Sources
- [4], [5], [6]
- Caveats
- The two meta-analyses disagree on VO2 max [4][6]. The 2025 abstract reports no confidence intervals and notes heterogeneity [4]. Reference [5] is narrative.
Endurance and aerobic capacity
Small trials found mixed results: one review found better endurance in athletes, while trained cyclists showed no change and older adults gained in thresholds only.
The numbers and sources
- Effect
- In a meta-analysis of fungal supplements in athletes (14 RCTs, 528 athletes, 8 pooled), Cordyceps sinensis improved endurance (p 0.05), ventilatory threshold (p 0.03) and VO2 peak (p 0.04) [1]. In 22 trained male cyclists, 3 g a day of CordyMax Cs-4 for 5 weeks did not change VO2 peak, ventilatory threshold or time trial results [2]. In 20 adults aged 50 to 75, Cs-4 for 12 weeks raised metabolic threshold 10.5% and ventilatory threshold 8.5%, and VO2 max did not change [3]. In 28 young adults, a mushroom blend with Cordyceps militaris showed no change after 1 week, and in the 10 who continued for 3 weeks VO2 max rose 4.8 mL/kg/min [4].
- Population
- Athletes [1], trained cyclists [2], healthy older adults [3], young adults [4].
- Sources
- [1], [2], [3], [4]
- Caveats
- Trials are small and disagree. The meta-analysis abstract gives p-values without effect sizes, and its search included a Chinese database [1]. Trial [4] tested a blend, not cordyceps alone.
Exercise performance
Limited evidence: one review reported better aerobic and anaerobic performance but was found to contain errors, and strength trials found no effect.
The numbers and sources
- Effect
- A meta-analysis of 15 studies reported improved aerobic performance (SMD 0.84, 95% CI 0.12 to 1.56, I² 89%) and anaerobic performance (SMD 0.24, 95% CI 0.05 to 0.43) [10]. A 2025 published comment identified errors in that analysis, including outlier effect sizes, effect estimates that needed recalculating with standard deviations, and one included study that appeared to compare arginine with citrulline rather than placebo [11]. A meta-analysis of 3 trials of acute arginine alone in strength training found no effect on muscular endurance (0.26, 95% CI -0.13 to 0.65) or peak torque [12]. In a crossover trial of 4 days at 3.2 to 9.6 g a day, total biceps curl repetitions, volume load, fatigue and plasma nitric oxide did not differ from placebo [13].
- Population
- Athletes and active adults [10][12]. 16 recreationally trained young men [13].
- Sources
- [10], [11], [12], [13]
- Caveats
- Sources disagree. Aerobic results had very high heterogeneity [10].
Endurance and exercise metabolism
Limited evidence: some small trials reported better endurance, one only with added carbohydrate, while a CrossFit trial found no change.
The numbers and sources
- Effect
- In 30 publications in healthy people, carnitine raised blood carnitine and changed resting VO2, with no change in blood lactate at rest or after exercise [5]. In 14 healthy men, 2 g of L-carnitine L-tartrate with 80 g of carbohydrate twice daily for 24 weeks raised muscle carnitine 21%, cut muscle glycogen use 55% at low intensity, and raised work output 11% from baseline; carbohydrate alone did not change it [6]. A 2026 systematic review of 18 randomized placebo-controlled trials in active people reported better endurance performance after single doses of 2 to 15 g and after 2 to 3 g a day for 2 to 24 weeks, with no change in fat oxidation during exercise [7]. In 20 trained men, 3 g of L-carnitine L-tartrate 90 minutes before a 20-minute CrossFit workout did not change repetitions completed (202.4 against 204.5) [8].
- Population
- Healthy adults [5]; 14 young men [6]; active people in 18 trials [7]; 20 recreational CrossFit athletes [8].
- Sources
- [5], [6], [7], [8]
- Caveats
- The single trial is small, and the carbohydrate was needed to raise insulin and move carnitine into muscle [6]. The meta-analysis reports dose in "g/dL", which appears to be a unit error [5]. The 2026 review did not pool results, and none of its trials was at low risk of bias [7].
Physical performance
Limited evidence: large effects came mostly from animal tests, and a small trial in basketball players found no difference from placebo.
The numbers and sources
- Effect
- A meta-analysis of 16 studies reported large effects on forced swimming, rota-rod and grip strength tests and lower blood lactate [8]. In a crossover trial in 10 well-trained college basketball players, 2,000 mg a day for 2 weeks did not differ from placebo in jump height, shooting accuracy, repeated sprints, fatigue index or lactate clearance [9].
- Population
- Animal and human studies [8]. 10 male basketball players [9].
- Sources
- [8], [9]
- Caveats
- The outcomes are largely animal tests. The abstract does not report a separate human effect [8]. The basketball trial was small and short [9].
Exercise performance
Not shown to improve VO2 max or exercise performance in athletes or healthy adults, though it raised blood CoQ10.
The numbers and sources
- Effect
- Across 24 studies, CoQ10 consistently raised blood CoQ10. Performance effects were small and inconsistent. A small chronic benefit was no longer stable after outliers were removed, and acute dosing showed no benefit [11]. In athletes, VO2max did not change (7 studies, SMD 0.03, 95% CI -0.32 to 0.39), nor did anaerobic threshold [12]. Across 14 RCTs (433 participants), VO2max and blood lactate did not change [13]. In 33 trials (3,317 participants) in adults aged 40 and over, VO2peak rose 0.73 mL/kg/min (95% CI -0.07 to 1.54), compatible with no benefit, and estimates for walking distance, grip and leg strength, chair rises and lean mass were uncertain [14].
- Population
- Healthy adults in randomized trials [11]; athletes and trained people [12]; exercising adults [13]; middle-aged and older adults [14].
- Sources
- [11], [12], [13], [14]
- Caveats
- Certainty was very low to low [11][14]. Risk of bias raised some concerns in 23 of 24 athlete studies [12].
Repeated sprints
Not shown to change repeated sprint performance or fatigue across 17 trials, at any dose or duration tested.
The numbers and sources
- Effect
- Across 17 RCTs, beta-alanine taken for 2 weeks or more did not change mean repeated sprint performance (SMD -0.018, 95% CI -0.207 to 0.170), peak repeated sprint performance (0.205, 95% CI -0.073 to 0.483) or fatigue decrement (-0.020, 95% CI -0.516 to 0.476). Total dose, duration, exercise type and training status did not moderate the result [8].
- Population
- Healthy people in 17 placebo-controlled trials [8].
- Sources
- [8]
- Caveats
- One meta-analysis. The abstract does not report the pooled number of participants [8].
Aerobic endurance
Not shown to change aerobic performance, perceived effort or lactate in healthy adults across 10 trials.
The numbers and sources
- Effect
- Across 10 placebo-controlled studies, citrulline did not change aerobic performance (SMD 0.15, 95% CI -0.02 to 0.32), perceived exertion (-0.03), oxygen uptake kinetics (0.01) or lactate (0.25, 95% CI -0.10 to 0.59) [6].
- Population
- Healthy adults in aerobic tests [6].
- Sources
- [6]
- Caveats
- The authors note chronic protocols showed a positive tendency that has not been tested in enough trials [6].
Athletic performance and body composition
Not shown to change lean mass, body fat or VO2max in athletes. Body weight fell about 1.4 kg.
The numbers and sources
- Effect
- Across 25 trials in athletes over 18, glutamine did not change lean body mass, body fat percentage or VO2max. Body weight fell by 1.36 kg (95% CI -2.55 to -0.16) [1].
- Population
- Athletes, 47 studies reviewed and 25 pooled [1].
- Sources
- [1]
- Caveats
- One meta-analysis. The weight change is not explained by a lean mass or fat change in the same analysis [1].
Exercise performance
Not shown to change exercise performance in athletes and active adults, with a mean change of 0.29%.
Muscle and physical function
Not shown to preserve muscle mass or function in adults over 60. One trial found a longer six-minute walk in peripheral artery disease.
The numbers and sources
- Effect
- A meta-analysis of randomized trials in adults over 60 found no support for NR or NMN preserving muscle mass or function. NR was linked to a longer six-minute walk in peripheral artery disease, and to lower SPPB scores and slower chair stands in mild cognitive impairment [5]. In the peripheral artery disease trial, six-minute walk changed by +7.0 m on NR and -10.6 m on placebo, a difference of +17.6 m (90% CI +1.8 to +∞) at 6 months [6].
- Population
- Randomized trials in adults with mean ages of 60.9 to 83 [5]; 90 people with peripheral artery disease for 6 months [6].
- Sources
- [5], [6]
- Caveats
- The walking result is one trial with a one-sided interval. ChromaDex supplied the NR and placebo for it [6].
Endurance and strength performance
One small trial found choline citrate did not change run time to exhaustion or squat performance in 14 soldiers.
The numbers and sources
- Effect
- Choline citrate before and during 4 hours of loaded treadmill marching raised plasma choline 128% and did not change run time to exhaustion, squat performance or perceived exertion [10].
- Population
- 14 soldiers in a crossover trial [10].
- Sources
- [10]
- Caveats
- One small trial. Trials of alpha-GPC and citicoline, including memory and power output, are on the alpha-GPC page.
Muscle strength and performance
Limited evidence: no significant change in strength or power across trials. One small trial in exercisers found lower VO2max and sprint power on magnesium.
The numbers and sources
- Effect
- Across 14 RCTs, magnesium did not significantly change isokinetic peak torque (WMD 0.87, 95% CI -1.43 to 3.18), muscle strength (WMD 0.87, 95% CI -0.12 to 1.86) or muscle power (WMD 3.28, 95% CI -14.94 to 21.50). Benefits appeared more pronounced in older adults and people with alcoholism than in athletes [11].
- Population
- 215 athletes or active people, 95 untrained adults, and 232 older adults or people with alcoholism [11].
- Sources
- [11], [12]
- Caveats
- Fixed-effects pooling across mixed populations and outcomes. In a 2025 crossover RCT of 15 regular exercisers, 600 mg a day of magnesium chloride for 9 days lowered VO2max (44.4 vs 41.3 mL/kg/min, p = 0.005) and 30 second sprint power (439 vs 415 W, p = 0.03) against placebo, with no change in a 10 km time trial [12].
Training adaptation
One trial found muscle mitochondrial markers rose with endurance training on placebo but not with vitamin C plus E. VO2max rose 8% in both groups.
The numbers and sources
- Effect
- Over 11 weeks of endurance training, VO2max rose 8% with vitamin C plus E and 8% with placebo. Markers of mitochondrial growth in muscle rose on placebo (COX4 59%, PGC-1α 19%) but not with the vitamins (-13% and -13%) [13].
- Population
- 54 young men and women given 1,000 mg vitamin C and 235 mg vitamin E a day [13].
- Sources
- [13]
- Caveats
- One trial of a combination, so the result cannot be assigned to vitamin C alone. Performance did not differ between groups. Funders included Sana Pharma AS and Smartfish AS [13].
Training adaptation
One trial found muscle mitochondrial markers rose with endurance training on placebo but not with vitamins C plus E. VO2max rose 8% in both groups.
The numbers and sources
- Effect
- Over 11 weeks of endurance training, VO2max rose 8% with vitamins C plus E and 8% with placebo. Markers of mitochondrial growth in muscle rose on placebo (COX4 59%) but not with the vitamins (-13%) [11].
- Population
- 54 young men and women given 235 mg vitamin E with 1,000 mg vitamin C a day [11].
- Sources
- [11]
- Caveats
- One trial of a combination. Performance did not differ. Funders included Sana Pharma AS and Smartfish AS [11].
Therapies
Exercise performance, IV fluids against drinking
Small crossover trials disagreed: one found IV rehydration sped a 40 km cycling time trial by 3.5% against drinking, and another found drinking gave a faster time trial.
Compared with drinking fluids, sports drink and water [5]; drinking water [6]
The numbers and sources
- Effect
- After dehydration by 4% of body weight, rehydrating half with IV saline cut 40 km time trial time by 3.5% against oral rehydration, and oral glycerol by 3.7%. Combining IV fluid with oral glycerol restored the most plasma volume and did not improve performance over either alone [5]. During 90 minutes of cycling in 35°C heat, 25 mL of saline infused every 5 minutes left people thirstier and hotter, with a slower 12 km time trial (19.6 minutes) than drinking 25 mL of water every 5 minutes (17.7 minutes, P = 0.05) [6].
- Population
- 9 endurance-trained men [5]. Recreationally active men, mean age 29, number not given in the abstract [6].
- Sources
- [5], [6]
- Caveats
- Two small crossover trials with different designs. Neither tested recovery on the following days.
Practices
Walking distance and symptoms in heart failure
Shown to improve 6-minute walk distance and symptom class in people with heart failure, though the largest trial missed its main endpoint, the change in BNP.
The numbers and sources
- Effect
- In 149 hospitalized patients with advanced heart failure, 10 daily sessions improved NYHA class, 6-minute walk distance and cardiothoracic ratio only in the Waon group. The primary endpoint, the change in BNP, did not reach statistical significance [4]. Pooled sauna studies found 6-minute walk distance 48.11 m longer after 2 to 4 weeks [2]. In 41 patients, walk distance rose from 337 to 379 m after 3 weeks [5]. In 49 patients, physical and mental quality of life scores on the SF-36 improved after 3 weeks [6].
- Population
- 76 Waon and 73 control patients at 19 Japanese institutes, mean age 66 [4]. Participants in 16 articles [2]. 41 patients [5] and 49 patients [6] with chronic heart failure, no control groups.
- Sources
- [4], [2], [5], [6]
- Caveats
- The largest trial did not meet its primary endpoint [4]. Walking and symptom measures depend on effort and expectation, and no trial was blinded. Two of the studies had no control group [5][6].
Aerobic fitness in athletes
One sham-controlled trial found higher VO2 max after 40 sessions in middle-aged master athletes, with 31 of 37 randomized participants analyzed.
The numbers and sources
- Effect
- Compared with sham, 40 sessions at 2 ATA raised maximal oxygen consumption (p = 0.010, effect size 0.989) and oxygen consumption at the anaerobic threshold (effect size 0.837). Measures of mitochondrial respiration and mitochondrial mass in muscle also rose [15].
- Population
- 37 healthy master athletes aged 40 to 50, of whom 16 hyperbaric and 15 sham participants were analyzed [15].
- Sources
- [15]
- Caveats
- One small trial with 6 randomized participants missing from the analysis. The abstract reports effect sizes without the size of the VO2 max change.
Aerobic fitness when added to exercise
One trial found estimated VO2 max rose 2.7 mL/kg/min more when a 15-minute sauna followed each exercise session for 8 weeks, in 47 sedentary adults.
The numbers and sources
- Effect
- Estimated VO2 max rose 2.7 mL/kg/min more (95% CI 0.2 to 5.3) with exercise plus sauna than with exercise alone. Exercise alone raised it 6.2 mL/kg/min (95% CI 4.2 to 8.3) over the control group [3].
- Population
- 47 adults aged 49 ± 9 with low physical activity and at least one cardiovascular risk factor, randomized to exercise plus sauna, exercise or control for 8 weeks [3].
- Sources
- [3]
- Caveats
- One trial of about 16 people per group. VO2 max was estimated, not measured by gas analysis. There was no sauna-only group.
Endurance performance in trained runners
Small trials found longer run time to exhaustion and higher VO2 max in trained runners after 3 weeks of post-training sauna sessions.
The numbers and sources
- Effect
- In 6 male distance runners, 3 weeks of post-training sauna increased run time to exhaustion by 32% (90% confidence limits 21 to 43%) relative to control training, which the authors equate to about 1.9% in an endurance time trial. Plasma volume rose 7.1% [6]. In 20 middle-distance runners, 3 weeks of post-exercise sauna raised VO2 max by 0.27 L/min (p = 0.02) and running speed at 4 mmol/L blood lactate by 0.6 km/h (p = 0.01) more than training alone [7]. In 26 runners who all used the sauna, VO2 max rose 5% in both women and men [8].
- Population
- 6 competitive male runners in a crossover study [6]. 20 trained runners, 13 of them women, mean age 20 [7]. 26 trained runners, 16 of them women [8].
- Sources
- [6], [7], [8]
- Caveats
- Very small samples. The abstract of [7] does not say that groups were randomized, and [8] had no control group. Sessions were about 30 minutes at 90°C to 108°C straight after training.
Exercise performance
Mixed results: pooled trials found small gains in muscle endurance and cycling time to exhaustion, and no effect on strength, sprinting, running or swimming performance.
The numbers and sources
- Effect
- Across 37 double-blind crossover studies (586 participants) of light applied before exercise, muscle endurance in single-joint exercise improved (SMD 0.27, 95% CI 0.12 to 0.41) and so did cycling time to exhaustion (SMD 0.35, 95% CI 0.10 to 0.59). Strength (p = 0.92), cycling sprints (p = 0.96), running and swimming measures did not change [17]. An earlier review of 39 trials (861 participants) found some effect in favor of phototherapy on time to exhaustion, repetitions, peak torque and lactate, at very low to moderate quality [18]. In athletes, a meta-analysis of 24 studies reported better lower-limb strength up to 8 weeks when laser was applied before exercise [19].
- Population
- Healthy young adults [17]. Healthy people in 39 trials [18]. Physically active athletes in 24 studies [19].
- Sources
- [17], [18], [19]
- Caveats
- The reviews disagree on strength. Light doses, wavelengths and exercise tests varied widely, and samples were small [18].
Exercise performance with hyperventilation breathwork
Mixed results: a systematic review of Wim Hof Method trials found mixed effects of its breathing on exercise performance and on breathing during exercise.
Compared with control conditions the source abstract does not describe [19]
The numbers and sources
- Effect
- In a narrative synthesis of 9 papers from 8 trials, the effect of Wim Hof breathing on exercise performance was mixed, as were effects on minute ventilation, tidal volume and breathing frequency after exercise [19].
- Population
- Healthy people and people with medical conditions aged over 14 in 8 trials [19].
- Sources
- [19]
- Caveats
- No pooled estimate. Trials were small.
Performance when used before exercise
Limited evidence: a systematic review of 12 controlled studies found the effect of cryotherapy before exercise on performance unclear.
The numbers and sources
- Effect
- Of 12 controlled studies of whole-body or partial-body cryotherapy before exercise, 6 tested performance, 4 oxidative stress and 2 lysosomal enzymes. The reviewers judged the potential for favorable physical responses unclear, with little high-quality research available [24].
- Population
- Healthy or athletic participants in 12 studies [24].
- Sources
- [24]
- Caveats
- No pooled estimate. Protocols were not standardized across studies.
Endurance training adaptations
Not shown to change gains from endurance training, for better or worse, in one meta-analysis and a later 5-week trial.
The numbers and sources
- Effect
- Regular cold water immersion with endurance training had no effect on time-trial mean power or maximal aerobic power (SMD -0.07, 95% CI -0.54 to 0.53) or on time-trial duration (SMD 0.00, 95% CI -0.58 to 0.58) [7]. In 16 men doing interval training 3 times a week for 5 weeks, 15 minutes at 11.2°C after each session did not change VO2 max, running time to failure, or muscle markers of adaptation and inflammation relative to training alone [12].
- Population
- Participants in controlled endurance training studies [7]. 16 healthy men, 9 using cold immersion and 7 controls [12].
- Sources
- [7], [12], [6]
- Caveats
- Few small trials with wide intervals. An umbrella review found endurance performance improved immediately after immersion with no later benefit and no effect on adaptations [6].
Exercise performance and recovery
Not shown to improve exercise performance or recovery when given before or after exercise. A Cochrane review found more muscle soreness at 48 hours with immediate treatment.
The numbers and sources
- Effect
- In a meta-analysis of physically active adults, hyperbaric oxygen before exercise had no significant effect on performance and after exercise had no significant effect on recovery (10 studies reviewed, 6 pooled with 69 participants) [22]. A Cochrane review of 9 trials (219 participants) found higher pain at 48 hours in people given hyperbaric oxygen straight after muscle-damaging exercise (mean difference 0.88 on a 0 to 10 scale, 95% CI 0.09 to 1.67), with no difference in swelling or strength. Two trials in ankle sprain and knee ligament injury found no difference from sham [23].
- Population
- 166 physically active adults in 10 studies [22]. 219 participants in 9 small trials [23].
- Sources
- [22], [23]
- Caveats
- Small trials. Individual studies of oxygen breathed during exercise reported better muscle endurance, which could not be pooled [22].
Cardiovascular effects compared with exercise
One small trial found 45 minutes of infrared sauna raised body temperature but did not reproduce the breathing or cardiovascular responses of moderate cycling in 10 women.
The numbers and sources
- Effect
- Tympanic temperature was 1.05°C higher during infrared sauna than rest and 0.79°C higher than cycling. Respiratory rate was 6.66 breaths a minute higher during cycling than sauna. Blood pressure, arterial stiffness and heart rate variability did not differ between sauna, cycling and rest [11].
- Population
- 10 healthy women, mean age 36, in a randomized crossover of rest, infrared sauna and indoor cycling [11].
- Sources
- [11]
- Caveats
- Ten women, single sessions.
Daily life
Activity and fitness in step-count programs
Shown to add about 1,800 to 2,500 steps a day in trials of pedometers and activity trackers, with a small gain in fitness.
Compared with control participants [8]; control groups the source does not describe [9]; control groups in randomized trials [10]
The numbers and sources
- Effect
- In randomized trials, pedometer users raised their activity by 2,491 steps a day more than controls (95% CI 1,098 to 3,885). Having a step goal such as 10,000 steps predicted a larger rise [8]. Across 39 reviews, activity trackers raised physical activity (SMD 0.3 to 0.6), about 1,800 extra steps a day, and fitness (SMD 0.3) [9]. In people with type 2 diabetes, step counters added 1,822 steps a day (95% CI 751 to 2,894), and 3,200 when paired with a goal [10].
- Population
- 2,767 participants in 26 studies, 8 of them randomized, mean age 49, 85% women, mean 18 weeks [8]. 163,992 participants in 39 reviews of all ages [9]. 861 people with type 2 diabetes in 7 trials [10].
- Sources
- [8], [9], [10]
- Caveats
- People in trials could not be blinded to wearing a counter. Programs lasted months, and the earliest review called long-term durability undetermined [8].
Physical performance after a nap
Shown to improve physical test performance after an afternoon nap in two meta-analyses of athletes and active adults. Muscle force did not change.
Compared with a no-nap condition in randomized trials [3]; no-nap conditions [5]
The numbers and sources
- Effect
- After a normal night, a nap improved physical performance (SMD 0.99, 95% CI 0.67 to 1.31), with larger benefits for naps of 30 to under 60 minutes and when testing came more than an hour after waking [3]. In the 5-m shuttle run test, napping raised highest distance (effect size 1.026) and total distance (0.737) and lowered the fatigue index (0.839). Muscle force did not change (effect size 0.175, p = 0.267) [5].
- Population
- 291 males aged 18 to 35, 164 trained athletes and 127 active adults, in 22 trials [3]. Physically active people and athletes in 18 studies after 7 to 9 hours of night sleep [5].
- Sources
- [3], [5]
- Caveats
- Small crossover studies, mostly in young men. Heterogeneity was high (I² 89.1%) [3]. Sprint, jump and endurance results rested on one to three studies each [5].
Walking and physical activity
Linked to more walking in dog owners in one meta-analysis. In a controlled study, getting a dog added about 2,600 daily steps at 3 months, gone by 8 months.
Compared with people without a dog [5]; people who delayed getting a dog and people with no plans to get one [6]; young people without a family dog [7]
The numbers and sources
- Effect
- Dog owners walked more (d 0.26) and were more physically active (d 0.16) than non-owners. About 60% of owners walked their dog, a median 160 minutes and 4 walks a week [5]. People who got a dog took 2,589 more steps a day at 3 months (p = 0.004), and the gain was not maintained at 8 months [6]. In children and teenagers, 7 of 9 studies found more activity with a family dog [7].
- Population
- 29 studies, mostly cross-sectional, mostly in Australia and the US [5]. 71 adults, 17 of whom got a dog, followed 8 months [6]. 9 studies of youth [7].
- Sources
- [5], [6], [7]
- Caveats
- Most studies were cross-sectional, and active people may choose dogs. The controlled study let people choose their group and was small [6].
Physical activity
One randomized trial found a community garden plot added about 6 minutes a day of moderate to vigorous activity during the growing season, against a waiting list.
Compared with a waiting list for a community garden plot [7]
The numbers and sources
- Effect
- Moderate to vigorous physical activity showed a significant time-by-intervention effect (p = 0.012), with a mean between-group difference of 5.80 minutes a day (99.5% CI -4.44 to 16.05) by accelerometer. Sedentary time did not change [7]. Those who gardened the whole season reported a median 90 minutes a week at the garden [8].
- Population
- 291 adults aged 18 and older who had not gardened in 2 years, 145 given a plot [7]. 145 people in the gardening group [8].
- Sources
- [7], [8]
- Caveats
- One trial, with a strict confidence interval that crosses zero at the second time point [7]. 67% of the gardening group gardened the whole season [8].
Food and drink
Exercise performance
Shown to improve muscle strength and endurance, endurance tests, jumping and sport-specific actions after one energy drink, in pooled studies, with no significant effect on sprinting.
Compared with control or placebo conditions the abstract does not describe [4]
The numbers and sources
- Effect
- Energy drink intake improved muscle strength and endurance (effect size 0.49), endurance exercise tests (0.53), jumping (0.29) and sport-specific actions (0.51), and not sprinting (0.14, p = 0.06). Performance was associated with taurine dose and not with caffeine dose in a meta-regression [4].
- Population
- 34 studies published 1998 to 2015 [4].
- Sources
- [4]
- Caveats
- One review, with drinks varying in dose and ingredients. A different review found little evidence that ingredients other than caffeine improve performance [5]. Caffeine trials on their own are on the caffeine page.
Devices and wearables
Daily steps and physical activity
Shown to raise physical activity by about 1,800 steps a day across 39 systematic reviews of activity trackers in healthy and clinical groups.
The numbers and sources
- Effect
- An umbrella review of 39 systematic reviews and meta-analyses found activity trackers improved physical activity (SMD 0.3 to 0.6), equal to about 1,800 extra steps a day and 40 minutes a day more walking, and improved fitness (SMD 0.3) [18].
- Population
- 163,992 participants of all age groups, from healthy and clinical populations [18].
- Sources
- [18]
- Caveats
- The reviews cover wearable activity trackers as a class. They do not test whether heart rate or calorie readings themselves changed behavior [18].
Cardiorespiratory fitness with tracker use
Shown to raise fitness modestly across systematic reviews of activity tracker trials. One crossover study found a 1.5 mL/kg/min rise in estimated fitness over 8 weeks.
The numbers and sources
- Effect
- An umbrella review of 39 systematic reviews and meta-analyses found activity trackers improved fitness (SMD 0.3) and physical activity (SMD 0.3 to 0.6) [18]. In 50 inactive adults who followed their activity on a Garmin Vivosmart 4 for 8 weeks after a 4-week control period, estimated cardiorespiratory fitness rose by 1.52 mL/kg/min (95% CI 0.82 to 2.22) and daily steps by 982 (95% CI 492 to 1,471). Blood pressure did not change [19].
- Population
- 163,992 participants across 39 reviews [18]. 62 inactive adults recruited, 50 completed, mean age 48, 84% women [19].
- Sources
- [18], [19]
- Caveats
- These trials tested wearing an activity tracker, not seeing a VO2 max number. In the crossover study, participants were also instructed to reach 150 intensity minutes a week, there was no randomized control group, and fitness was reported as an estimate [19].
Endurance performance with training guided by daily readings
Not shown to improve endurance performance or VO2 max more than a fixed training plan in two meta-analyses of small trials.
The numbers and sources
- Effect
- Across 8 studies, training adjusted to daily heart rate variability had no significant effect over predefined training on performance (g = 0.079, p = 0.597) or peak oxygen uptake (g = 0.171, p = 0.130), and a significant effect on submaximal physiological measures (g = 0.296, 95% CI 0.031 to 0.562). Most guided programs included fewer moderate or high intensity sessions [22]. A second meta-analysis found small, non-significant differences for maximal aerobic capacity (SMD 0.20, 95% CI -0.07 to 0.47) and endurance performance (SMD 0.20, 95% CI -0.09 to 0.48) [23].
- Population
- 198 participants in 8 studies [22]. Trials of endurance training, the longest lasting 8 weeks [23].
- Sources
- [22], [23]
- Caveats
- Small trials using a range of recording devices and decision rules. One review reported fewer non-responders with guided training [22]. Its authors concluded that any advantage for group-level fitness or performance is by a small margin [23].