Normative Hamstrings and Quadriceps Isometric Strength Values and Hamstrings-Quadriceps Asymmetry in Healthy Collegiate Soccer and Basketball Players.

The objectives of this study were to report weight-normalized, sex- and sport-stratified normative values for hamstrings and quadriceps isometric strength in collegiate soccer and basketball players using a low-cost hand-held dynamometer and assess the prevalence of "substantial" hamstrings-quadriceps (H/Q) ratio strength imbalance (<0.6) among players. Ninety-four healthy collegiate male and female soccer and basketball players (age range: 18-24 years) were examined for baseline isometric hamstrings and quadriceps strength using a handheld isometric dynamometer with standardized and valid protocols. For soccer, the mean (95%CI) weight-normalized peak isometric strength values (considering dominant limbs) were 3.29 (2.90 to 3.64) N/kg (hamstrings) and 5.48 (4.96 to 6.00) N/kg (quadriceps) in male players and 2.62 (2.39 to 2.85) N/kg (hamstrings) and 4.55 (4.14 to 4.96) N/kg (quadriceps) in female players. For basketball, the mean (95% CI) peak strength values were 2.97 (2.72 to 3.21) N/kg (hamstrings) and 4.89 (4.44 to 5.33) N/kg (quadriceps) in male players and 2.48 (2.15 to 2.80) N/kg (hamstrings) and 4.21 (3.54 to 4.87) N/kg (quadriceps) in female players. The prevalence of substantial H/Q strength imbalance was 37% (95%CI: 24% to 52%) in soccer and 44% (95%CI: 29% to 60%) in basketball players. This study is first to provide normative values for peak isometric hamstrings and quadriceps strength using a low-cost hand-held dynamometer. The normative database from this study is valuable to coaches, sports medicine professionals, exercise scientists and other stakeholders to inform injury prevention, rehabilitation progression, return to play decisions and performance goals in collegiate soccer and basketball players.