Investigation of acute effect of cold and hot water immersion on hand grip strength and EMG values

The aim of this study was to investigate the acute effects of different water applications on upper extremity muscle activity and handgrip strength in 12 healthy male volunteers. Participants were divided into three groups of four individuals each and were randomly assigned to undergo 10 minutes of immersion in 40°C warm water (HSI), 10 minutes of immersion in 10°C cold water (SSI), and control (CONT) conditions on different days. In each condition, surface electromyography (sEMG) and handgrip strength measurements of the Flexor Carpi Radialis (FCR) and Flexor Carpi Ulnaris (FCU) muscles were taken before and after immersion of the dominant forearm in water. The obtained data were analyzed using analysis of variance (ANOVA) for repeated measures. The analysis results showed that the application factor had no significant effect on the EMG RMS values of both the FCR and FCU muscles (F(2,22) = 0.259, p = 0.775; F(2,22) = 0.373, p = 0.600) and the time factor (F(1,11) = 0.202, p = 0.662; F(1,11) = 0.635, p = 0.442) had no statistically significant effect on the EMG RMS values of both the FCR and FCU muscles. The interaction between application and time for the FCR muscle was also found to be insignificant (F(2,22)=1.866, p=0.178), and similarly, this interaction was not statistically significant for the FCU muscle (F(2,22)=2.552, p=0.101). Statistical analyses of changes in handgrip strength under different conditions and over time revealed that neither application (F(2,22)=0.499, p=0.614) nor time (F(1,11)=0.022, p=0.885) had a statistically significant effect on handgrip strength. In contrast, while the main effects of the condition (F(2,22)=0.499, p=0.614) and time (F(1,11)=0.022, p=0.885) factors were not found to be significant, the interaction between application and time was found to be statistically highly significant (F(2,22) = 8.206, p = 0.002). This critical finding indicates that the pre- and post-application effects of HSI, SSI, and KONT conditions on handgrip strength differ significantly from one another. The effect size of this interaction is quite high (η²p = 0.427). In conclusion, while HSI and SSI did not cause a significant and independent change in the overall activity levels of the FCR and FCU muscles, they did produce time-dependent and meaningful effects on functional outcomes such as handgrip strength. These findings suggest that the effects of thermal interventions on muscle performance may occur through more complex interactions rather than simple changes in activity. KEYWORDS: Hand Grip Strength, EMG, Immersion