TY - JOUR

T1 - Effect of environmental temperature change on the neuromechanical function of the quadriceps muscles

AU - Spillane, Pádraig

AU - Bampouras, Theo

N1 - This is an Accepted Manuscript of an article published by Taylor & Francis in European Journal of Sport Science on 14 Dec 2020, available online: https://www.tandfonline.com/doi/abs/10.1080/17461391.2020.1851773

PY - 2021/10/31

Y1 - 2021/10/31

N2 - This study compared neuromechanical characteristics of voluntary (maximum voluntary contraction (MVC) peak torque, rate of torque development (RTD), voluntary activation (VA)) and electrically stimulated contractions (peak torque, RTD) when performed under the same temperature conditions. Twelve physically active males performed two isometric MVCs of the knee extensors in an isokinetic dynamometer. The MVCs were performed after lower limb submersion for 20 minutes in hot (40°C) or cold (10°C) water. A control MVC was performed in ambient room temperature (17 ± 0.7°C). Electrical twitches were delivered at rest pre-MVC (Unpotentiated), during the plateau phase of the MVC (Superimposed) and post-MVC (Potentiated). Peak torque for MVC, Unpotentiated and Potentiated was recorded. RTD was calculated for the MVC (at 50 ms, 100 ms, 150 ms, 200 ms and peak torque time points), Unpotentiated and Potentiated twitches, while muscle activation capacity (using the central activation ratio method) was calculated. There was no significant change between conditions in MVC peak torque, MVC RTD, muscle activation capacity and (averaged) twitch peak torque (P >0.05). Twitch RTD for the hot condition (1025.0 ± 163.0 N·m ·s-1) was significantly higher (P=0.003) than control (872.3 ± 142.9 N·m ·s-1). In conclusion, environmental temperature changes, in the range examined, do not affect the ability to generate maximum torque or any of the RTD parameters in maximum voluntary isometric contractions. In contrast, increased heat results in higher RTD in electrically stimulated contractions, most likely induced by reduced contraction time. This has practical implications for the use electromyostimulation tools for injury prevention.

AB - This study compared neuromechanical characteristics of voluntary (maximum voluntary contraction (MVC) peak torque, rate of torque development (RTD), voluntary activation (VA)) and electrically stimulated contractions (peak torque, RTD) when performed under the same temperature conditions. Twelve physically active males performed two isometric MVCs of the knee extensors in an isokinetic dynamometer. The MVCs were performed after lower limb submersion for 20 minutes in hot (40°C) or cold (10°C) water. A control MVC was performed in ambient room temperature (17 ± 0.7°C). Electrical twitches were delivered at rest pre-MVC (Unpotentiated), during the plateau phase of the MVC (Superimposed) and post-MVC (Potentiated). Peak torque for MVC, Unpotentiated and Potentiated was recorded. RTD was calculated for the MVC (at 50 ms, 100 ms, 150 ms, 200 ms and peak torque time points), Unpotentiated and Potentiated twitches, while muscle activation capacity (using the central activation ratio method) was calculated. There was no significant change between conditions in MVC peak torque, MVC RTD, muscle activation capacity and (averaged) twitch peak torque (P >0.05). Twitch RTD for the hot condition (1025.0 ± 163.0 N·m ·s-1) was significantly higher (P=0.003) than control (872.3 ± 142.9 N·m ·s-1). In conclusion, environmental temperature changes, in the range examined, do not affect the ability to generate maximum torque or any of the RTD parameters in maximum voluntary isometric contractions. In contrast, increased heat results in higher RTD in electrically stimulated contractions, most likely induced by reduced contraction time. This has practical implications for the use electromyostimulation tools for injury prevention.

KW - Cooling

KW - Heating

KW - Maximum voluntary contractions

KW - Muscle activation

KW - Rate of torque development

KW - Post-activation potentiation

U2 - 10.1080/17461391.2020.1851773

DO - 10.1080/17461391.2020.1851773

M3 - Journal article

VL - 21

SP - 1394

EP - 1402

JO - European Journal of Sport Science

JF - European Journal of Sport Science

SN - 1746-1391

IS - 10

ER -