Journal Title (Medline/Pubmed accepted abbreviation): Sports Med
Page numbers: 995-1017
Article type: Review
Summary of article:
This review discusses the current clinical evidence for the effects of several dietary supplements in team-sport performance enhancement. Team-sport performance relies on multiple abilities, including speed, strength, power, and repeated and intermittent sprints; dietary supplements that improve a single performance aspect may be less effective during team sports. Ribose, a relatively new dietary supplement, may increase ATP resynthesis rate and recovery from high-intensity training sessions without adverse events. Clinical evidence of benefit is mixed; therefore, ribose cannot currently be recommended for team-sport performance. Caffeine may improve intermittent sprint performance, alertness, and reaction time, but may not affect repeated sprint performance. Caffeine is also associated with several adverse events, including increased heart rate and blood pressure. Creatine supplementation may increase glycogen reserves and ATP resynthesis; however, clinical evidence for improved team-sport performance is mixed and effects may be similar to caffeine. Branched-chain amino acids (BCAAs) have been suggested to reduce fatigue and muscle damage following exercise; however, clinical trials have not supported these claims and few trials have been conducted in areas of sports performance other than fatigue. A metabolite of BCAA, β?hydroxy?β?methylbutyrate (HMB), has also been investigated. Although HMB supplementation can improve strength and increase lean body mass, enhanced aerobic fitness or anaerobic power/endurance has not been demonstrated. Moreover, the benefits of HMB supplementation on lean body mass or strength have not been replicated in several studies conducted in trained athletes, suggesting that the benefit of HMB supplementation in elite, team-sport athletes remains undetermined. Sodium bicarbonate increases buffering capacity and supports normal pH during exercise. Clinically, sodium bicarbonate ingested before exercise can improve both intermittent- and repeated-sprint performance with minimal adverse effects (usually gastrointestinal). β-alanine, a precursor to carnosine, may also enhance muscle buffering. Several clinical trials have demonstrated a benefit of β-alanine supplementation on total work, power at maximum oxygen uptake, isokinetic performance, time to exhaustion, and mean and peak power during isokinetic task. However, the potential benefit of β-alanine on multiple-sprint performance in team-sport athletes is unclear because the single trial to test this performance aspect did not demonstrate benefit. Additionally, large acute doses of β-alanine may produce some degree of paresthesia. Bovine colostrum has improved endurance sport performance in several studies. In one trial evaluating team-sport performance, sprint, jump, and endurance performance were enhanced, although no clear mechanism exists for these effects. No studies have reported adverse events.
Interpretation of findings/Key practice applications:
Clinical evidence supports caffeine, creatine, and sodium bicarbonate for improvement of multiple-sprint performance. Research tends to support β-alanine and bovine colostrum for team-sport performance, although further research is necessary to recommend these agents. Ribose, BCAAs, and HMB are not supported by the current evidence as supplements for team-sport performance. Typical supplemental regimens include 6 mg/kg for caffeine, 20 g/day for 5 to 7 days for creatine, and 0.2 to 0.3 g/kg 60 to 120 minutes before exercise for sodium bicarbonate. Limitations of these studies include a lack of evidence for women, adolescents, and children. In addition, there is a general lack of studies on team sport performance vs other activities (eg, cycling, running, weight training) in the sports nutrition/exercise physiology literature. Finally, the effects of multiple supplements and possible ingredients not listed on supplement packaging should be considered as well.