Research Team Members: Barnett Frank, PhD, ATC, Claudio Battaglini, PhD, Troy Blackburn, PhD, ATC, Anthony Hackney, PhD, DSc, Darin Padua, PhD, ATC
Why did you do this study?
Lack of physical activity is directly responsible for 9% of global premature mortality. Remarkably, exercise is consistently identified as a fundamental health behavior to effectively reduce one’s risk of disease. However, exercise participation carries a concerning high risk of musculoskeletal injury. Musculoskeletal injury amounts to a socioeconomic burden >6% of the U.S. gross domestic product. Paradoxically, injury is the primary barrier to exercise participation. Thus there is a need to prevent exercise-related musculoskeletal injury to promote the health and quality of life enhancing benefits of exercise.
Faulty movement patterns (i.e. knee collapsing and stiff hips and knees when landing – Figure 1) and elevated biochemical markers of musculoskeletal tissue stress are predictive of future injury during physical activity participation. Exercise interventions aimed at correcting faults in motion during physical activity reduce risk of injury. However, the underlying physiological mechanisms by which movement patterns modify risk for injury are unknown.
Abnormal movement patterns are theorized to impart a greater cumulative physical stress and systemic demand on the body during exercise, resulting in musculoskeletal system tissue failure and ultimately injury. Currently, it is unknown if there is a combined effect of an individual’s movement profile and exercise exposure on tissue and systemic stress measures associated with injury.
The purpose of this research was to investigate the influence of an individual’s movement profile on their physiological and biomechanical response to high training loads experienced during exercise and sport participation. Specifically, we investigated if a high injury risk / “stiff” or a low injury risk / “soft” movement profile affects the body’s systemic stress (cortisol), muscle loading (creatine kinase), cartilage degradation, and biomechanical response to high training load exposure.
What did you do and what did you find in this study?
43 college-aged female athletes were enrolled in this study and were assigned to a low-risk / “soft” (n=22) or a high-risk / “stiff” (n=21) movement profile group using a clinical movement injury risk assessment – The Landing Error Scoring System (Figure 1.) Jump-landing 3D biomechanics and blood samples were collected prior to and following a high training load exercise bout (Figure 2 & 3). Changes in biomechanics, circulating biomarkers of joint cartilage (cartilage oligomeric matrix protein) and skeletal muscle loading (creatine kinase), and of systemic stress (cortisol), were compared between movement profiles to better understand the influence of movement profile on the body’s response to the demands of exercise exposure (Figures 2 & 3).
We observed the high-risk / “stiff” landing group to experience greater degradation of movement strategies that effectively and efficiently dissipate landing forces experienced during high-intensity exercise. Specifically, we observed the high-risk / “stiff” group to land with a high-load landing posture and greater landing forces compared to the low-risk / low-load group when exposed to exercise. Furthermore, we observed movement profile to influence systemic stress hormone levels. Individuals with a high-risk / “stiff” movement profile exhibited an elevated stress level in contrast to their low-risk / “soft” landing profile counterparts. Additionally, it seems the low-risk / “soft” movement profile is linked to greater utilization of dynamic muscle tissue to efficiently dissipate the high loading stresses experienced during exercise and physical activity.
Interestingly, we did not observe a direct influence of movement profile on cartilage loading during exercise. However, we observed greater variability of cartilage loading responses in the high-risk / “stiff” landing group (standard deviation = ±43.9%) with over 1.5 times the range of responses compared to the low-risk / low-load group (standard deviation = ±29.4%). Implicating individuals with a low-risk / “soft” movement profile have a more uniform cartilage loading response compared to their high-risk / “stiff” landing counterparts.
How do these findings impact the public?
This study is the first to identify movement profile as a moderator of systemic responses to exercise. Collectively our findings suggest that an individual with a movement profile associated with a lower risk of injury may be more mechanically and systemically resilient to exercise exposure. Decreased system resilience in individuals with high-risk / “stiff” movement profiles may explain their elevated risk of sustaining a debilitating musculoskeletal injury during physical activity. Correcting a physically active individual’s faulty movement patterns may enhance their response to exercise while also decreasing their risk of musculoskeletal injury.