UC Riverside Undergraduate Research Journal

The knee joint faces daily stresses that cause its overall health to degrade and pathologies to develop. I hypothesized that increased stress on the knee joint and imbalance in thigh musculature would positively correlate with increased acoustic emissions from the knee joint, a biomarker of inflammation in the joint. We tested this hypothesis by selecting a cohort of healthy, moderately active individuals aged 18-32 across a range of BMIs. We collected baseline knee acoustic measurements and measured quadricep and hamstring flexibility, hamstring and quadricep maximum voluntary isometric contraction, and heel strike angle during self-selected walking gait. Heel strike angle does not correlate with increased acoustic emissions from the knee, but BMI negatively correlates with the hamstrings:quadriceps strength ratio. Furthermore, left hamstring flexibility positively correlates with left heel strike angle. Finally, we found that right quadricep flexibility had a positive correlation with right heel strike angle. Since the hamstrings:quadriceps strength ratio is an important biomarker for knee health, this finding may indicate evidence of progressing knee pathology in individuals with higher BMI. Changes in gait associated with muscle rigidity indicate that differential levels of upper leg muscle flexibility may translate to changes in the mechanics of everyday movements, such as walking.