A pilot study on the effects of far-infrared-emitting fabric on neuromuscular performance of knee extensor and male fertility

The aim of this study was to evaluate the time course of the effects of far-infrared emitting fabric (FIR) on neuromuscular performance of knee extensor over 120 h and to investigate whether the use of FIR affects semen. This is a crossover, randomized, double-blind, and placebo-controlled trial split into neuromuscular and fertility assessments. Four (28.8 ± 4.7 years old) and six (29 ± 3.9 years old) healthy, resistance-trained males completed all neuromuscular and fertility assessments, respectively. In neuromuscular assessments, for five consecutive days, the participants underwent neuromuscular tests in an isokinetic dynamometer (maximal isometric voluntary contraction (MVC) and fatigue test) every 24 h in both conditions (FIR and Placebo). In fertility assessments, participants performed three semen collections: Baseline, FIR, and Placebo. FIR and Placebo collections were performed after five consecutive days of use of the pants. Conventional parameters and sperm DNA fragmentation were evaluated. In the FIR condition, the participants showed significant differences in total work at 96 h (p < 0.001; Cohen’s d = 3.73), 120 h (p = 0.01; Cohen’s d = 2.65), and pre-MVC at 120 h (p = 0.02; Cohen’s d = 2.15) when compared to Placebo. FIR did not significantly (p > 0.05) affect the conventional semen parameters or sperm DNA fragmentation compared to Baseline or Placebo. FIR improved the knee extensor neuromuscular performance of healthy resistance-trained individuals, with 112.4 ± 7.8 h accumulated, and did not affect their seminal parameters (conventional or sperm DNA fragmentation), with 113.1 ± 10.2 h accumulated.