Towards Standardized Instructions For Measuring Perception Of Effort And Muscle Pain During Physical Exercise

Abstract

PURPOSE: Perceptions of effort (PE) and muscle pain (MP) influence performance and engagement in regular physical exercise. Literature-based standardized instructions describe PE as resulting from multiple sensory cues including “aches”. This description of PE creates a possible confound when PE and MP are being considered separately. This project uses standardised, confound-free instructions and tests their validity during cycling exercise. METHODS: After removing confounding factors from PE’s instructions (Borg, 1998), we used The Borg CR Scales® Folder (Borg, 2008) to adapt these instructions to the CR100 scale®. MP was measured with instructions available from Cook et al. 1997 and adapted to the CR100 scale®. For availability in English and French, the instructions were translated and back-translated following standardised procedure. Semantic validity was confirmed by bilingual participants (N = 8) during pilot testing. Then, twenty-two participants visited the laboratory thrice. During the first visit, participants performed an incremental test to exhaustion to determine their cycling peak power output (PPO). During both visits 2 and 3 (randomized order), subjects performed four 1 min cycling bouts at 4 workloads (40, 60, 80, 100% PPO) twice. The bouts were separated by either 15 min of rest or a time to exhaustion test at 80% PPO. PE and quadriceps MP intensity were assessed during each exercise. Differences were tested using Friedman tests on the values reported at each workload and the change scores between workloads. RESULTS: During the incremental test, changes in PE and MP in response to changes in workloads were dissociated only for power outputs below 50% PPO (P < 0.001). During the 1 min cycling bouts, changes in PE and MP in response to changes in workloads were dissociated (P < 0.001). Following completion of the time to exhaustion test, PE and MP increased (P < 0.001). During each exercise, PE was higher than MP (~10 a.u., P < 0.001). CONCLUSION: The observed difference in the intensity of PE and MP, as well as their response to changes in workload provide experimental support in favour of the use of confound-free instructions to monitor PE and MP during cycling exercise. Future studies should test this possibility for other exercise modalities involving similar and other muscle groups.