(43) RELIABILITY OF EXERCISE-INDUCED HYPOALGESIA DURING LUMBOSACRAL DYNAMIC RESISTANCE EXERCISE

Purpose: Exercise can acutely reduce pain sensitivity in healthy individuals and has been termed exercise-induced hypoalgesia (EIH). As an extension-based dynamic resistance exercise targeting the spinal flexors and extensors, the 45-degree Roman Chair exercise allows for direct progressive overload and, if used as an intervention, would allow for greater endurance of the lumbosacral musculature. Furthermore, this exercise has the potential to elicit EIH in the lumbosacral region for healthy and clinical populations. However, the ability of this exercise to reliably produce EIH with a multi-modal protocol has not been examined. Therefore, the purposes of this study were to evaluate the reliability of heat pain threshold (HPT) and pressure pain threshold (PPT), investigate local and systemic EIH effects at the lumbar paraspinal (LP) and upper trapezius (UT) muscles following the 45-degree Roman chair exercise, as well as determine the consistency of EIH responses between sessions. Methods: Thirty-five healthy participants (mean(SD) age: 21(1.39) years, 16 male) completed two identical sessions separated by at least 48 hours. HPT and PPT were measured over the UT and LP before and after a period of quiet rest to assess reliability. The same measures were repeated before and after one set of bodyweight 45-degree Roman chair exercise performed for as many repetitions as possible to evaluate the reliability of EIH. Intraclass Correlation Coefficients (ICC_3,1) assessed reliability, while paired samples t-test and three-way repeated measures ANOVA analyzed changes in HPT and PPT following quiet rest and exercise. Results: Participants completed mean (SD) repetitions: 36(11) on the Roman chair. HPT and PPT demonstrated good (HPT: ICC_3,1 >0.741) to excellent reliability (PPT: ICC_3,1 >0.810). Significant EIH, measured by PPT, was observed at both the UT (p< 0.025, η_p² >0.138) and LP (p< 0.001, η_p² >0.413), with larger effect sizes at the LP. HPT showed significant EIH at the LP (p< 0.002) but not at the UT (p=0.059). EIH was consistently induced between sessions over the LP with good-to-excellent reliability and strong correlations (ICC_3,1 HPT=0.903, PPT=0.815; r HPT=0.903, PPT=0.814) and UT (ICC_3,1 HPT=0.867, PPT=0.729; r HPT=0.877 and PPT=0.744). Conclusions: In healthy individuals, the 45-degree Roman chair can reliably produce significant hypoalgesia in the LP using multimodal measures of pain threshold. Practical Applications: This study demonstrates that the 45-degree Roman chair may be a beneficial and practical exercise for strength and conditioning specialists as this exercise allows for reductions in pain sensitivity in the exercising musculature and requires minimal equipment and familiarization. Additionally, this exercise shows potential for reliably reducing pain sensitivity and producing EIH, suggesting it could serve as both a potential intervention and outcome measure. Acknowledgements: None