This study examined the effects of curcumin and fenugreek soluble fiber supplementation on the ventilatory threshold (VT) and peak oxygen consumption ( V ˙ O2 peak). Methods: Forty-five untrained men and women were randomly assigned to one of three supplementation groups: placebo (PLA, n = 13), 500 mg·day−1 CurQfen® (CUR, n = 14), or 300 mg·day−1 fenugreek soluble fiber (FEN, n = 18). Participants completed a maximal graded exercise test on a cycle ergometer to determine the VT and V ˙ O2 peak before (PRE) and after (POST) 28 days of daily supplementation. Separate, one-way analyses of covariance (ANCOVAs) were used to examine the between-group differences for adjusted POST VT and V ˙ O2 peak values, covaried for the respective PRE-test values. Results: The adjusted POST VT V ˙ O2 values for the CUR (mean ± SD = 1.593 ± 0.157 L·min−1) and FEN (1.597 ± 0.157 L·min−1) groups were greater than (p = 0.039 and p = 0.025, respectively) the PLA (1.465 ± 0.155 L·min−1) group, but the FEN and CUR groups were not different (p = 0.943). There were no differences in the adjusted V ˙ O2 peak values (F = 0.613, p = 0.547) among groups. Conclusion: These findings indicated that fenugreek soluble fiber was responsible for the improvements in the submaximal performance index for both CUR and FEN groups.

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...

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