Estimating the dynamic ratio of the lateral/medial hamstrings. A case control study

Abstract

Purpose. Hamstring injuries are among the most common injuries in sports. The current study estimates the hamstrings dynamic ratio (HDR) between the mean muscle activation of lateral (biceps femoris longus) and medial part (semitendinosus) of the hamstring muscles during a maximal voluntary isometric contraction in elite uninjured track and field athletes. Methods. Following isokinetic assessment to estimate the hamstrings to quadriceps dynamic ratio (H:Q), the participants were divided in two groups (Group 1 (N = 10): Athletes with a H:Q ratio range 55-70% and no side to side difference of the ratios more than 6 units; and Group 2 (N = 8) athletes with a H:Q ratio outside of the 55-70% range and/or a side to side difference of the ratios greater than 6 units). All athletes were assessed by electromyography during a maximum voluntary isometric contraction of their hamstrings. Results. There was difference on the range and means between the two groups regarding hamstrings dynamic ratio (78% and 69% respectively), although this difference did not reach statistical significance. Conclusions. A proposed HDR of 78% between lateral to medial hamstrings could be used as a risk factor for hamstring injuries in athletes with hamstring muscle imbalances. Better characterisation of the normal patterns of hamstring muscle activation will allow targeted rehabilitation to address specific neuromuscular coordination patterns. © 2021, CIC Edizioni Internazionali s.r.l.. All rights reserved.