Sensory mapping of the upper trapezius muscle in relation to consecutive sessions of eccentric exercise

The aim of this study was to evaluate the changes in pressure pain sensitivity maps in untrained subjects over 2 subsequent sessions of eccentric exercise (ECC) expected to result in (a) delayed onset muscle soreness (DOMS) and (b) adaptation/recovery, respectively. Eleven healthy male subjects participated in this study. Pressure pain threshold (PPT), rate of perceived exertion (RPE), pain intensity, soreness area drawing, maximal voluntary contraction (MVC), and shoulder range of motion were assessed in session 1 before, immediately after, and 24 hours after ECC. The ECC protocol that was used to induce DOMS consisted of 50 eccentric contractions of the right shoulder that were divided into 5 bouts, including 10 contractions at MVC level separated by a 2-minute resting period. Session 2 was identical to session 1 and performed exactly 1 week later. There was only a significant increase in the RPE assessed before the exercise and 24 hours after the exercise in session 1 (p = 0.001). The average PPT only decreased significantly from before the exercise (660.2 ± 76.2 kPa) to 24 hours after the exercise (435.6 ± 59.3 kPa) in session 1 (p = 0.016). The present study confirmed a heterogeneous distribution of mechanical sensitivity before and after sessions of ECC. The first session of ECC underlined increased mechanical sensitivity because of DOMS, whereas the second session reflected an adaptation process. Our results support the potential role of ECC bouts in training regimens.