Musculoskeletal disorders are prominent in the United States and account for over 130 total healthcare encounters annually, which include hospital, outpatient, and emergency room visits. Annual costs for muscle injuries range between $45-54 billion in healthcare costs, lost wages, and worker’s compensation and result in significant time loss in the workplace and athletic arenas. Massage is an increasingly popular treatment for muscle injury. Despite the popularity of this modality, the effects of massage on passive mechanical properties are not well-understood and the forces applied along the muscle belly have not yet been quantified. The lack of quantification of forces applied during massage and the varied massage protocols utilized across various studies make it difficult to compare results between studies and therefore determine the efficacy of this manual therapy.

In this dissertation, the effects of immediate and 48 hour delayed massage on skeletal muscle passive mechanical property recovery were explored. Additionally, an attempt to quantify and relate the loading applied along the muscle to active and passive property recovery was investigated. Thus, this work aims to characterize tissue mechanical property changes in response to massage and attempts to further address the initiative of the National Center for Complementary and Alternative Medicine by addressing key questions of massage therapy through well-designed scientific studies.

A quasi-linear viscoelastic (QLV) model was used to characterize tissue mechanical properties in response to eccentric exercise (EEC) injury and consecutive bouts of massage. Twelve New Zealand White rabbits underwent a damaging bout of EEC and passive mechanical property evaluations were performed pre-EEC, post-EEC, pre- and post-massage for 4 consecutive days, and following a 4 day massage protocol. Animals were subjected to either immediate massage (n=6) or massage delayed by 48 hours (n=6) following exercise. Immediate and delayed massage resulted in 53% and 41% reduction in tissue stiffness over the 4 day protocol, respectively. Moreover, tissue stiffness reduction was greater within-day rather than over the course of 4 days and parameters associated with the tissue’s relaxation response were not affected by massage.

The previous work was extended by investigating and quantifying the peak forces applied along the muscle belly (transverse) between immediate and delayed massage for all 4 days of application. Transverse forces had a direct relationship with compressive force magnitude and an indirect relationship with loading frequency. Immediate massage resulted in larger transverse forces than delayed massage and the forces were greatest in the second 5 min of each massage bout compared to the first 5 min.

Finally, the combination of kinetic parameters were quantified and related to active and passive property recovery to determine a better understanding of the mechanical loads applied during massage. Loading along the muscle belly had a strong correlation with tissue stiffness recovery both within-day and between consecutive massage sessions, but predicted an inverse relationship with active property recovery. These findings provide evidence of the importance of massage loading, its effects on tissue and joint function, and may further insight in aiding clinical decision-making for proper dosing of massage therapies following EEC injury