THE IMPACT OF REMOTE AND LOCALIZED KNEE PAIN ON MAXIMAL STRENGTH, FATIGUE PARAMETERS, AND FORCE RECOVERY IN THE KNEE EXTENSOR MUSCLES OF RECREATIONALLY ACTIVE COLLEGE AGED INDIVIDUALS

Abstract

Pain is a widely experienced sensation that has been shown in previous research to decrease duration of exercise and maximal strength. PURPOSE: The purpose of this study was to determine if the application of knee pain impacts time-to-task failure and maximal strength measures. It also aimed to see if changing the location of knee pain between the ipsilateral (dominant) leg and the contralateral (non-dominant) impacted fatigue parameters, maximal strength differently and force recovery. METHODS: Participants (Females = 9, Males = 12, N/A = 1) completed five visits (2 familiarization and 3 experimental) separated by 48 hours. At the beginning of each of the visits, the electrical stimulus for participants to reach pain threshold and pain rated a 4/10 in the knee was obtained. The exercise protocol consisted of four pre-exercise MVCs (Maximal Voluntary Contractions), submaximal time-to-task failure protocol (intensity of 15% over critical torque), and 6-post exercise MVCs with the different conditions being contralateral knee pain, ipsilateral knee pain or no knee pain. RESULTS: The male participants had a higher MVC and twitch torque than the female participants (p<0.001) indicating males were stronger than women. Pre-exercise MVCs decreased significantly following application of knee pain, likely due to an increase in central fatigue (p<0.001). There was a main effect of time in force decrease (p<0.001), twitch torque (p<0.001), and % activation (p=0.005) during submaximal protocol. Regardless of pain condition, force output was fully recovered 240 seconds after exercise failure (p=0.067). Subjective pain measures of exercising muscle pain, regardless of condition, were increased at 60 seconds (p=0.030), immediately before failure (p=0.004), and immediately following exercise (p=0.007). When pain was applied to the ipsilateral knee, pain ratings decreased significantly over time, likely due to exercise induced hypoalgesia (p<0.001). Pain ratings in the ipsilateral knee were greater in the ipsilateral condition than they were in the control condition or the contralateral knee pain condition (p<0.001). When pain was applied to the contralateral knee, pain ratings were different over time also likely due to exercise induced hypoalgesia (p<0.001). Pain ratings in the contralateral knee were greater in the contralateral condition than they were in the control condition or the ipsilateral knee pain condition (p<0.001). CONCLUSIONS: The presence of knee pain regardless of location decreased MVCs and increased percent activation of the participants. Knee pain stimulus regardless of location did not impact time-to-task failure. Peripheral fatigue increased throughout the fatiguing exercise protocol. Maximal strength was recovered 240s after fatiguing exercise regardless of the presence and location of knee pain.