title: Hamstrings strength imbalance in professional football (soccer) players in Australia.
abstract: The aim of this study was to describe the isokinetic thigh muscle strength profile of professional male football players in Australia. Concentric (60° and 240°·s(-1)) and eccentric (30° and 120°·s(-1)) hamstrings and quadriceps isokinetic strength was measured with a HUMAC NORM dynamometer. The primary variables were bilateral concentric and eccentric hamstring and quadriceps peak torque ratios, concentric hamstring-quadriceps peak torque ratios, and mixed ratios (eccentric hamstring 30°·s(-1) ÷ concentric quadriceps 240°·s(-1)). Hamstring strength imbalance was defined as deficits in any 2 of: bilateral concentric hamstring peak torque ratio <0.86, bilateral eccentric hamstring peak torque ratio <0.86, concentric hamstring-quadriceps ratio <0.47, and mixed ratio <0.80. Fifty-five strength tests involving 42 players were conducted. Ten players (24%) were identified as having hamstring strength imbalance. Athletes with strength imbalance had significantly reduced concentric and eccentric bilateral hamstring peak torque ratios at all angular velocities tested; and reduced eccentric quadriceps peak torque (30°·s(-1)) in their stance leg, compared with those without strength imbalance. Approximately, 1 in 4 players had preseason hamstring strength imbalance; and all strength deficits were observed in the stance leg. Concentric and eccentric hamstrings strength imbalance may impact in-season football performance and could have implications for the future risk of injury.
authors.affiliation: 1School of Allied Health, La Trobe University, Melbourne, Australia; 2Department of Physiotherapy, La Trobe University, Melbourne, Australia; and 3Australian Institute of Sport, Canberra, Australia.
authors.forename: Clare L
authors.initials: CL
authors.lastname: Ardern
authors.forename: Tania
authors.initials: T
authors.lastname: Pizzari
authors.forename: Martin R
authors.initials: MR
authors.lastname: Wollin
authors.forename: Kate E
authors.initials: KE
authors.lastname: Webster
mesh_terms: D000293:Adolescent; D000328:Adult; D001315:Australia; D005080:Exercise Test; D006801:Humans; D008297:Male; D009119:Muscle Contraction; D053580:Muscle Strength; D053581:Muscle Strength Dynamometer; D052097:Quadriceps Muscle / Q000502:physiology*; D012916:Soccer / Q000502:physiology*; D013848:Thigh; D019415:Torque; D055815:Young Adult