Participant and Researcher Perceptions of Stretching Intensity and Muscle Tension in A Hamstrings and Shoulder Stretch in Healthy Young Adults

Stretching research and practice relies heavily on internal and clinical perceptions of stretching sensation to prescribe intensity due to the lack of equipment required. No research has assessed the relationship between internal and external perceptions of stretch intensity. The purpose of this study was to assess the relationship between participants' stretch sensation and researchers' perception of muscle tension in two passive stretches; supine hip flexion and shoulder extension. Training status and stretching experience were considered with the 18 young adult participants. Joint angles at which participants signaled initial stretch sensation and maximum tolerable stretch for each protocol were recorded by a secondary researcher. The blinded primary researcher recorded joint angles where initial tension and maximum tension were perceived as they executed passive stretching of the participant. While there was evidence of greater hip flexion ROM for women, athletes, participants with stretching experience, as well as with stretching to maximum versus initial point of discomfort, there were no significant differences between the participants and researcher's measurements at initial or maximum endpoints, however correlation and agreement between participant and researcher perceptions were variable. There was an overall large magnitude (eta² = 0.794), non-significant difference (p = 0.06) with researcher maximum (108.39° ± 17.22) hip flexion measurements higher than participants (98.6° ± 20.08). This mean difference was more apparent with the greater divergence with less trained individuals and stretching experience. Shoulder extension ROM did not reveal any group differences (i.e., sex, trained state, stretch experience). This research demonstrated excellent reliability overall of participant and researcher perceptions for hip flexion and shoulder stretches with lower correlations for sedentary and inexperienced individuals. Results highlight the need for training status and stretching experience to be considered in stretching intensity prescription and scale development.