Hamstrings-to-quadriceps strength and size ratios of male professional soccer players with muscle imbalance

The aim of this study was to determine the correlation between the concentric hamstrings/quadriceps muscle strength (H-con:Q(con)) and cross-sectional area ratios (H-csa:Q(csa)) in professional soccer players with H-con:Q(con) imbalance. Nine male professional soccer players (253 +/- 41years) performed five maximal concentric contractions of the knee extensors (KE) and flexors (KF) at 60s(-1) to assess H-con:Q(con). The test was performed using the dominant (preferred kicking), and non-dominant limb with a 5-min recovery period was allowed between them. Only players with H-con:Q(con)<060 (range: 045-059) in both limbs were included in this study. The muscle cross-sectional area (CSA) of KE and KF was determined by magnetic resonance imaging. The correlations between H-con:Q(con) and H-csa:Q(csa) in the dominant leg (r=-033), non-dominant leg (r=019) and in the both legs combined (r=028) were not statistically significant (P>005). Thus, the H-con:Q(con) seems not to be determined by H-csa:Q(csa) in professional soccer players with H-con:Q(con) imbalance.