Effects of brief and prolonged cold application on maximal isometric handgrip strength

Abstract

IntroductionNeuromuscular effects of cold highlight a decrease in nerve conduction velocity, which supports its analgesic impact, and muscle tone and strength reduction. However, it has been suggested that cold could increase strength with short-time applications. The study aimed to compare the effects of brief and prolonged cold application on maximal isometric handgrip strength.MethodsThe controlled randomized clinical trial involved 112 volunteers (56 men and 56 women, mean age: 22 ± 2.1 years), randomly assigned to brief cooling group (BC, <i>n</i> = 36), prolonged cooling group (PC, <i>n</i> = 40), and control group (<i>n</i> = 36). BC received quick icing in anterior forearm, while PC and control group received ice pack application and no treatment, respectively. Three sessions with 3-day intervals were performed. Handgrip strength was assessed with hand-held dynamometry before and after treatment. The main outcome was maximal isometric strength difference (MISdiff).ResultsThere were statistically significant between-group differences in MISdiff in the 3 sessions (S1: <i>p</i> = 0.018; S2: <i>p</i> < 0.001; S3: <i>p</i> < 0.0001), showing a strength increase in BC (<i>p</i> < 0.0001) and decrease in PC (<i>p</i> = 0.025) at the end of the sessions. In addition, a post-intervention strength increase in BC was highlighted when analysing the sessions individually (S1: <i>p</i> = 0.0003; S2: <i>p</i> = 0.00147; S3: <i>p</i> = 0.0001).ConclusionsBrief cold seems a good strategy to increase maximal isometric strength, although the underlying neurophysiological mechanisms must be further studied. Brief cooling could be considered as an ergogenic low-cost support when isometry training is required. In turn, a strength decrease after prolonged cooling was observed.