From the study:
Muscle endurance (ie, resistance to fatigue) was assessed on the right hand (FDI) and leg skeletal (TA) muscles by measuring the number of contractions during repeated isometric contractions until fatigue using a custom-built exercise apparatus19,20 at baseline, 2 months, and 4 months. The contraction intensity was set at 70% of the maximum voluntary contraction, and the exercise began at a frequency of 60 contractions per minute (cpm) for the first minute and increased at a rate of 10 cpm each minute until exhaustion.
To assess the effect of urolithin A supplementation on muscle endurance, we measured the ability to maintain repeated voluntary contractions to 70% of maximum voluntary contraction in the FDI and TA. At the 2-month visit, urolithin A supplementation significantly improved endurance in both muscles compared with placebo (urolithin A: FDI, 95.3 [115.5] and TA, 41.4 [65.5]; placebo: FDI, 11.6 [147.4] and TA, 5.7 [127.1]) (Figure 2D-I; eFigure 2A and B in Supplement 2). At the 4-month visit, endurance in the urolithin A group continued to improve, but a parallel increase in the placebo group led to no significant effect of treatment.
We further analyzed plasma samples to investigate the effect of urolithin A on biomarkers of mitochondrial health and inflammation. Urolithin A supplementation led to a significant reduction in several acylcarnitines, primarily long-chain and polyunsaturated species, at both the 2-month and 4-month visits compared with baseline (Figure 3A-D; eFigure 4A and B in Supplement 2). In addition, several species from a panel of ceramides that were analyzed via plasma metabolomics showed a significant reduction from baseline measurement in the urolithin A group but not the placebo group at both 2 and 4 months (Figure 3E and F; and eFigure 4C and D in Supplement 2).
To further test the effect of urolithin A on inflammation, we measured plasma levels of the inflammatory biomarker CRP. As for ceramides, a significant reduction from baseline in plasma CRP was observed in participants in the urolithin A group but not the placebo group (baseline vs 4 months: urolithin A, 2.14 [2.15] vs 2.07 [1.46]; placebo, 2.17 [2.52] vs 2.65 [1.86]) (Figure 3G).
this molecule looks like it does the same work as NMN and NR —but from a different angle.