Effects of Curcumin and Fenugreek Soluble Fiber on the Physical Working Capacity at the Fatigue Threshold, Peak Oxygen Consumption, and Time to Exhaustion

Abstract

Curcumin, a polyphenol, has been suggested to improve metabolic byproduct clearance and increase nitric oxide production in working muscle. These purported effects may delay neuromuscular fatigue. Therefore, the purpose of this study was to examine the effects of curcumin in combination with fenugreek (CUR) or fenugreek soluble fiber alone (FEN) on the neuromuscular fatigue threshold (PWCFT), time to exhaustion (Tlim) on a graded exercise test (GXT), and ̇O 2peak in untrained subjects. Forty-seven, college-aged, aerobically untrained individuals were randomly assigned to one of three supplementation groups; placebo (PLA, n=15), curcumin + fenugreek, CurQfen® (CUR, n=18), or fenugreek soluble fiber (FEN, n=14). All subjects performed a maximal GXT on a cycle ergometer to determine the PWCFT, Tlim, and V̇O2 peak before (PRE-test) and after (POST-test) 28 days of daily supplementation. Statistical analyses included 3 separate, one-way ANCOVAs to determine if there were any differences among the groups (PLA, CUR, FEN) for adjusted post-test scores for the PWCFT, V̇O2peak, and Tlim. The respective pre-test score was used as the covariate. In addition, reliability analyses (PRE-to POST-test) for the PLA group were used to calculate the minimal difference needed to be real (MD). The adjusted POST PWCFT values showed no statistical differences between groups (F= 3.141p= 0.053); however pairwise LSD comparisons indicated a significant difference between the CUR and PLA groups (p= 0.016), but not between the CUR and FEN groups. Therefore, separate one-way ANCOVAs were used to examine the adjusted PWCFT means for the PLA vs. CUR (F = 4.906, p =0.035) and the PLA vs. FEN (F = 2.969, p = 0.097). The one-way ANCOVA for ̇O 2 peak (F= 0.612 p= 0.547) and Tlim (F = 0.688, p = 0.508) values showed no statistical difference among the groups. Individual responses in each group showed ~ 20% of subjects in the CUR group, ~ 7% in the FEN group, and ~6% in the PLA group had values greater than the MD for the PWCFT, but none of the subjects in the PLA, FEN, or CUR groups exceeded the MD for ̇O 2 peak or Tlim. These findings indicated CurQfen® supplementation increased the PWCFT compared to a placebo, but not compared to fenugreek soluble fiber alone. However, there were no effects of CurQfen® on V̇O2 peak or Tlim. The mechanisms responsible for delaying time to neuromuscular fatigue may include increased NO production and increased blood flow to remove metabolic byproducts; however, the cellular changes which could lead to increases in Tlim and ̇O 2 peak may not have been sensitive to the GXT protocol or the given dosage of curcumin supplementation. Considering individual responses, CurQfen® supplementation resulted in a real change in the PWCFT for a small portion of the subjects (~20%). These findings suggested that CurQfen® supplementation without exercise training may help to improve time to neuromuscular fatigue in certain individuals, but the group mean analyses were not necessarily reflective of the responses for a majority of the...

Effect of curcumin supplementation on exercise-induced muscle damage: a narrative review

“…Others have hydrolysed the plasma samples before analysis [ 23 , 25 , 43 ], thus overestimating the true concentration of curcumin in the blood and making it difficult to accurately correlate any observed changes in levels of inflammatory markers to plasma curcumin levels. Finally, although some researchers [ 54 ] have reported that curcumin supplementation increased working capacity at the fatigue threshold and delayed the onset of neuromuscular fatigue, they did not analyse common inflammatory markers such as IL-6, TNF- α , and CK, also hindering comparisons between studies [ 54 ].…”

“…Another study examining the effects of curcumin in combination with fenugreek soluble fibre (CUR + FEN) or fenugreek soluble fibre alone (FEN) on the physical working capacity at the fatigue threshold (PW CFT ), peak oxygen consumption (V̇O 2 peak), and time to exhaustion ( T lim ) on a graded exercise test in untrained subjects for 28 days [ 54 ], showed no effect of curcumin supplementation on V̇O 2 peak or T lim . However, the PW CFT was greater after combined supplementation with curcumin and FEN compared with a placebo in ~20% of subjects [ 54 ].…”

Role of Turmeric and Curcumin in Prevention and Treatment of Chronic Diseases: Lessons Learned from Clinical Trials

“…In another study, 500 mg of HydroCurc (curcumin with LipiSperse) and 500 mg of maltodextrin after exercise reduced capillary lactate dehydrogenase, overall muscle pain, and thigh circumference in young and healthy males with strength training experience . In another randomized controlled trial, curcumin (190 mg/day) and fenugreek fiber (300 mg/day) for 28 days enhanced the neuromuscular fatigue threshold after exercise in untrained college-aged subjects ( n = 47) . A randomized, double-blind, placebo-controlled clinical trial demonstrated that curcumin (1000 mg/day) reduced audio-reaction time, choice-based visual reaction time, and improved memory in 18 volunteers aged 30–65 years .…”

“…180 In another randomized controlled trial, curcumin (190 mg/day) and fenugreek fiber (300 mg/day) for 28 days enhanced the neuromuscular fatigue threshold after exercise in untrained college-aged subjects (n = 47). 181 A randomized, double-blind, placebo-controlled clinical trial demonstrated that curcumin (1000 mg/day) reduced audio-reaction time, choice-based visual reaction time, and improved memory in 18 volunteers aged 30−65 years. 182 This study also showed that curcumin-galactomannan (1000 mg/day) supplementation resulted in a remarkable increase in αand β-waves of the brain and decreased the α/β ratio, audio-reaction time, choicebased visual reaction time, and improved memory in these volunteers.…”

The Anabolic Effect of Fenugreek: A Systematic Review with Meta-analysis

“…Concerning aerobic performance, both significant and non-significant effects were found. So the current data situation about endurance performance is ambiguous [25][26][27][28]. Regarding strength training and the change in body composition, such as fat-free mass and fat mass, no systematic analysis and summaries have yet been conducted.…”