Knee Extensor Torque Is Increased By Far-Infrared Emitting Fabric

Abstract

Far-infrared (FIR) emitting materials can increase the availability of nitric oxide and calcium in cell culture, and delay fatigue during ex-vivo skeletal muscle contractions. However, FIR effects on humans’ neuromuscular performance remains unknown. PURPOSE: To verify the effects of FIR emitting fabric on knee extensors torque and electromyography activity. METHODS: Fourteen healthy strength trained men (24.3 ± 4 years; 82.8 ± 11.3 kg; 176.3 ± 4.2 cm, 7.3 ± 2.9 years of training experience) participated in one familiarization and two experimental sessions. Experimental sessions occurred two weeks apart and after 96 hours of continuous FIR or Placebo fabric usage, in a randomized, crossover, double-blind, placebo-controlled design study. Isometric and dynamic torques were assessed using isokinetic dynamometer. The best result out of 3 maximum ballistic knee extension contractions (MBC) was recorded pre- and post-dynamic test. Dynamic test was composed by 30 maximum repetitions of knee flexion and extension at 180°/s. Peak torque (PT) of each repetition, total work (TW) and fatigue index (FI) of knee extensors were recorded. The mean RMS was calculated from electromyography activity records of superficial quadriceps muscles. Mean quadriceps temperature was assessed pre-protocol with a thermal camera. RESULTS: See table. FIR fabric increased pre and post MBC and trend to increase TW. RMS at isometric and dynamic tests, FI, and quadriceps temperature did not change. Additionally, FIR fabric demonstrated higher values of PT at 8th, 12th to 14th and 17th repetitions (all p < 0.05). CONCLUSION: FIR emitting fabric is effective to increase isometric and dynamic neuromuscular performance. Further, the absence of changes in electromyography activity and increased performance in single MBC, lead us to suggest that FIR effects are related to muscle contractile machinery improvements.