Effects of roller massager on muscle performance, morphology, and oxygenation after exercise-induced muscle damage

This study determined roller massager (RM) effectiveness on ankle plantar flexors’ recovery after exercise-induced muscle damage (EIMD) stimulus. Two experiments were conducted. The first experiment (n=10) examined functional [i.e., ankle plantar flexion maximal voluntary isometric contraction (MVIC) and submaximal (30% of MVIC) sustained force; ankle dorsiflexion maximal range of motion and resistance to stretch; and pain pressure threshold] and morphological [medial gastrocnemius (MG) cross sectional area, thickness, fascicle length, and fascicle angle] variables, before and immediately, 1h, 24h, 48h, and 72 after EIMD. In the second experiment (n=10), changes in MG deoxyhemoglobin concentration kinetics (velocity and amplitude) during a submaximal sustained force test were observed before and 48h after EIMD. Participants performed both experiments twice, with and without (NRM) the application of a RM (6 × 45 seconds with 20 seconds rest between sets). RM intervention did not alter plantar flexors’ strength and flexibility impairment after EIMD, as well the MG morphology and oxygenation kinetics (p>0.05). On the other hand, a strong tendency for an acute (within 1 hour) change of ipsilateral (post-effects: RM=+19%, NRM=-5%, p=0.032) and contralateral (p=0.095) MG pain pressure threshold was observed. In conclusion, the present results suggest that a roller massager has no effect on muscular performance, morphology, and oxygenation recovery after EIMD, except for muscle pain pressure threshold (i.e., a soreness). Thus, RM may have potential application in recovery for people with increased muscle soreness, if performed immediately before a physical task.

Kinematic and electromyographic analysis of the overhead squat in individuals showing excessive medial knee displacement

Dynamic knee valgus is a multi-planar motion that has been associated with anterior cruciate ligament injuries and patellofemoral pain syndrome. Clinical assessment of dynamic knee valgus can be made by looking for the visual appearance of excessive medial knee displacement (MKD) in the double-leg squat (DLS). The purpose of this dissertation was to identify the movement patterns and neuromuscular strategies associated with MKD during the DLS. Twenty-four control subjects and eight individuals showing MKD during the DLS participated in the study. Significant differences were verified between subjects that demonstrated MKD and a control (CON) group for the eletromyographic amplitude of adductor magnus, biceps femoris, vastus lateralis and vastus medialis muscles (p < 0.05), during the descending phase of the DLS. During the ascending phase were found group differences for adductor magnus and rectus femoris muscles (p < 0.05). Results from kinematic analysis revealed higher minimum and maximum values of ankle abduction and knee internal rotation angles (p < 0.05) for the MKD group. Also, individuals showing excessive MKD had higher hip adduction/abduction excursion. Our results suggested that higher tibial internal rotation and knee internal rotation angles in the initial position of the DLS are associated with MKD. The neuromuscular strategies that contributed to MKD were higher adductor magnus activation, whereas biceps femoris, vastus lateralis and vastus medialis activated more to stabilize the knee in response to the internal rotation moment.