Reference
Bai KY, Liu GH, Fan CH, et al. 12-week curcumin supplementation may relieve postexercise muscle fatigue in adolescent athletes. Front Nutr. 2022;9:1078108.
Study Objective
To determine if daily curcumin supplementation in adolescent athletes reduces postexercise fatigue
Key Takeaway
Turmeric supplementation may have an effect on postexercise muscle fatigue in adolescent athletes.
Design
Nonrandomized, unblinded, prospective cohort study
Participants
Twenty-eight participants (21 male and 7 female; mean age 17±1 years) completed the study.
Inclusion criteria: Middle- and high-school athletes who were training in tennis, soccer, or wrestling at least 20 hours per week for the past year.
Exclusion criteria: Regular dietary supplement intake, reported allergy to curcumin, preference to not take curcumin supplements, and inability to train 20 hours per week during the study period.
Of the original 60 participants evaluated for the study, 49 participants were enrolled in the study, and 21 were lost to follow-up (10 did not complete the second survey; 11 did not adhere to curcumin supplementation).
Intervention
Participants in the active group received 1.5 g Jiang Huang Powder containing 1,200 mg curcumin, 190 mg starch, and 10 mg sodium carboxymethyl cellulose daily for 12 weeks. Each participant was able to opt in or out of the intervention group. The control group did not use a placebo.
Study Parameters Assessed
Investigators determined muscle fatigue and muscle soreness using a visual analog scale from 0 to 10 where 0 suggests no fatigue or soreness and 10 suggests maximum fatigue or soreness.
Investigators measured serum levels of tumor necrosis factor alpha (TNF-α) and creatine kinase (CK) and urinary levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) at baseline and after 12 weeks of supplementation.
They also used multidimensional fitness assessments, including grip and back strength, balance via closed-eyes foot balance, flexibility via seated trunk flexion and extension, muscle endurance via sit-ups, power via vertical jump, and agility via reaction time and side steps.
Primary Outcome
Muscle fatigue and muscle soreness in young athletes after 12 weeks of daily curcumin supplementation. Secondary outcomes included blood markers of inflammation and oxidative stress.
Key Findings
Muscle fatigue mean score decreased from 6±1 to 4±2 (P=0.005). Muscle soreness mean score decreased from 7±2 to 4±2 (P=0.005).
Urinary 8-OHdG mean value decreased from 4.79 to 3.86 ng/mg creatinine (P<0.036). Changes in CK, MDA, and TNF-α results did not reach significance.
Transparency
Chang Gung Memorial Hospital Grants Study financially supported the study, and the authors declare no conflict of interest.
Practice Implications & Limitations
This study by Bai KY, Liu GH, Fan CH, et al, suffers from some significant limitations. The control group was not provided a placebo, and thus, the active group was unblinded to receiving the studied material, which may have contributed to performance bias. Also, the assessors were not blinded, which may have contributed to detection bias.
Further limiting general extrapolation from this study is that the participants were not randomized. Each participant elected to receive (or not receive) the study material, which is a selection bias. This study lost a lot of participants to follow-up, and the small sample size reduces the power to detect effects, especially in subgroup analysis such as male vs female.
The biochemical analysis was weak regarding inflammatory markers. The investigators did not measure several important inflammatory markers. They also did not record or control nutritional intake. Training was logged, but a standardized protocol was not provided. In fact, the investigators recruited from 3 diverse sports: wresting, tennis, and soccer.
The investigators did not measure several important inflammatory markers.
While the study reports the findings in terms of “curcumin” in its title and text, turmeric may be the more appropriate term rather than the isolated active constituent curcumin. Based on the typical curcumin content of turmeric, the reported 1,200 mg turmeric daily equates to approximately 35 to 60 mg curcumin daily.1 The study authors did not respond to correspondence by the time of this review submission.
Aside from these limitations, this study is unique in its choice of demographics and duration of supplementation with turmeric. Exercise-induced muscle damage (EIMD), delayed-onset muscle soreness (DOMS), and oxidative stress have been primary outcome measures in previous clinical trials, systematic reviews, and meta-analyses involving turmeric or curcumin products.2-7 However, many of these studies are of very short duration or were done during off-training periods. None evaluate adolescents.
With the study’s design limitations, serious practice implications are challenging. Integrative medicine clinicians often recognize curcumin (curcuminoids) and turmeric as a useful anti-inflammatory and oxidative-stress intervention. As such, it may already be included in recommendations for exercise overuse and occasional pain of joints and muscles. This study adds to the body of evidence showing turmeric supplementation reduces 8-OHdG, which is a commercially available assay to assess oxidative stress. Unfortunately, due to the outstanding question of precisely how much curcumin was found in the presumptive turmeric powder, we cannot make even preliminary commentary about the role of turmeric or curcumin for adolescent athletes based on this study.
Common dosages of turmeric supplements range from 300 to 1,500 mg per day, with total curcuminoid amounts ranging from 30 mg to 1,350 mg. Additionally, various delivery systems that affect absorption also contribute to the diversity of products on the market.
In light of the wide use and strong safety profile of these supplements, the most prudent action when considering this intervention for postexercise muscle fatigue among adolescent athletes may be to follow label recommendations of supplement manufacturers.
Your Conflict-of-Interest Disclosure
Author is employed by a manufacturer and distributor of dietary supplements, including turmeric supplements (Gaia Herbs).
