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Effects of Tissue Loading due to Massage on Muscle Mechanical Property Recovery Following Eccentric Exercise: 2097 Board #249 June 2, 2: 00 PM - 3: 30 PM.

PURPOSE: Although massage is an increasingly popular modality for a variety of musculoskeletal disorders, including chronic low back pain and exercise-induced muscle injury, the relationship between the applied mechanical loading parameters and clinical outcomes have not yet been elucidated. The purpose of this work was to investigate the contributions of several kinetic parameters on the recovery of both active and passive mechanical properties of skeletal muscle following an intense bout of eccentric exercise (EEC). METHODS: Twelve New Zealand White rabbits were subjected to EEC-induced muscle injury and randomly selected to undergo a 15 min constant compressive force massage (10 N) applied at a loading frequency of 0.5 Hz either immediately after EEC (n=6) or 48 hrs post EEC (n=6). The total amount of transverse loading (i.e. applied longitudinally along the muscle) was quantified by calculating the mechanical power and what was termed the mechanical “dose”. Recovery indices (RI), which compared the amount of recovery in active and passive mechanical properties to the initial change due to EEC, were calculated. The effects of the kinetic parameters on daily (RI) and between-day (RI’) recovery indices of tissue stiffness and isometric torque production recovery following four days of massage were determined. RESULTS: Transverse loading had moderate correlations with RI (tissue stiffness reduction) with immediate massage (power: r = -0.45; dose: r = -0.42), but weak relationships with delayed massage (power: r = -0.15; dose: r = -0.29). The increases in tissue stiffness between-day (RI’) also had moderate correlations with transverse loading with immediate massage (power: r = 0.48; dose: r = 0.49), but weak correlations with delayed massage (power: r = -0.31; dose: r = 0.22). Total mechanical dose (r = 0.46 and -0.40 for immediate and delayed conditions, respectively) and average mechanical power (r = -0.39 and -0.45 for immediate and delayed conditions, respectively) over the 4 day massage protocol predicted an inverse relationship with active property recovery. CONCLUSIONS: These findings provide evidence of the importance of mechanical loading, its effects on tissue and joint function, and further insight in aiding clinical decision-making for proper dosing of massage therapies following EEC injury.