Is hamstrings-to-quadriceps torque ratio useful for predicting anterior cruciate ligament and hamstring injuries? A systematic and critical review

Background: For the past 30 years, the hamstring (H)-to-quadriceps (Q) torque ratio (H:Q) has been considered an important index of muscle strength imbalance around the knee joint. The purpose of this systematic review has been to examine the value of H:Q torque ratio as an independent risk factor for hamstring and anterior cruciate ligament (ACL) injuries. Methods: Database searches were performed to identify all relevant articles in PubMed, MEDLINE, Cochrane Library, and Scopus. Prospective studies evaluating the conventional (concentric H:Q), functional (eccentric H: concentric Q), and mixed (eccentric H at 30°/s: concentric Q at 240°/s) H:Q ratios as risk factors for occurrence of hamstring muscle strain or ACL injury were considered. Risk of bias was assessed using the Quality In Prognosis Studies tool. Results: Eighteen included studies reported 585 hamstrings injuries in 2945 participants, and 5 studies documented 128 ACL injuries in 2772 participants. Best evidence synthesis analysis indicated that there is very limited evidence that H:Q strength ratio is an independent risk factor for hamstring and ACL injury, and this was not different between various ratio types. Methodological limitations and limited evidence for ACL injuries and some ratio types might have influenced these results. Conclusion: The H:Q ratio has limited value for the prediction of ACL and hamstring injuries. Monitoring strength imbalances along with other modifiable factors during the entire competitive season may provide a better understanding of the association between H:Q ratio and injury

Association between ankle muscle strength and postural sway in older adults

Our study aimed to investigate the relationship between the strength of ankle muscles and postural sway in older adults during upright standing tasks of varying difficulty. Forty-three elderly participants (20 women) performed maximal isometric contractions and three distinct postural tasks: normal quiet stance (60 s), tandem stance (20 s), and one-legged stance (10 s) on a pressure platform. Postural sway was comprehensively assessed, considering center of pressure velocity, peak-to-peak amplitude, and standard deviation of center of pressure displacement in both anterior/posterior and medio/lateral directions. Additionally, weight distribution asymmetry in both directions served as a quantifiable index. Surface electromyographic (EMG) activity of the Tibialis Anterior, Medial Gastrocnemius, Rectus Femoris, and Semitendinosus was recorded during the postural tasks. Throughout the balance tasks, isometric plantar and dorsiflexion torque exhibited a consistent decrease as posture variables increased (p < 0.001). Narrowing the base of support led to significant increases in all postural variables and EMG activity (p < 0.01), with a more pronounced effect on ankle muscles compared to hip muscles (p < 0.0005). In the normal quiet stance (r =.683) and tandem stance (r =.641), greater center of pressure velocity correlated with a more symmetrical weight distribution between the legs. These results suggest that ankle muscle strength serves as a reliable predictor of static balance control, particularly in postures involving a narrow stance. Therefore, the enhancement of plantar flexors and dorsiflexors, rather than an exclusive focus on symmetrical weight distribution, is more likely to contribute to improved static balance control in older adults