Grant Chesbro1, Daniel J. Larson1, Michael J. Wenger1, Christopher D. Black1 FACSM, & Rebecca D. Larson1

1University of Oklahoma, Norman, Oklahoma

Critical Torque (CT) is thought to be a key measure of the relationship between performance and fatigue. CT is the greatest force production that can be supported by oxidative metabolism with no progressive accumulation of lactate or inorganic phosphate. Previous research has suggested that resistance and aerobic training might impact CT, but to our knowledge, no study has examined the relationship between training status (TS) and CT. PURPOSE: The purpose of the present study was to examine differences in CT based on TS. METHODS: Thirty-three individuals participated in the study and were split into three groups: 12 Untrained (UT), 12 Resistance Trained (RT), and 9 Aerobic Trained (AT) based on self-reported training time. The participants completed 3 maximal voluntary isometric contractions (MVC) and the highest of the 3 was used to determine maximal strength. After a 5-minute rest period, the participants completed a 5-minute maximal protocol consisting of 30 six-second contractions followed by a four-second rest. Following the protocol, the participants were asked to provide rating of perceived exertion (RPE). RESULTS: The RT (365.39Nm±77.44) group had higher maximal strength than the AT group (271.23Nm±78.91; p=0.019). There were no between-group differences for absolute CT (UT: 121.65 Nm±24.80, AT: 149.73Nm±35.51, RT: 136.26 Nm±34.71; p=0.147). When CT was normalized to MVC however, the AT group (56.37%±11.36) had a higher relative CT compared to the RT (37.65%±7.60; p<0.001) and UT (39.88%±7.89; p<0.001). In addition, there was a between-group difference in impulse above critical torque (IACT) where the RT group (10146.76N∙m∙s±2886.51) had higher IACT compared to the AT group (6578.65N∙m∙s±3823.71; p=0.025). There were no differences between groups for post-exercise RPE (p=0.144). CONCLUSION: To our knowledge this is the first study to directly assess the differences in CT based on TS. Our data suggests that TS impacts CT assessments. There was also a wide range of relative CT values within groups with the UT group ranging from 24-51%, the AT group ranging from 38-70%, and the RT group ranging from 22-47% of MVC. These findings are important for researchers to consider as it impacts the common assessment of CT when assigning the load for a fatiguing task using MVC.

ACKNOWLEDGEMENTS: Funding for this project was provided by the Robberson Research Grant from the University of Oklahoma and the Helen Riddle Research Scholarship from the University of Oklahoma.

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