title: Alterations to the orientation of the ground reaction force vector affect sprint acceleration performance in team sports athletes.
abstract: A more horizontally oriented ground reaction force vector is related to higher levels of sprint acceleration performance across a range of athletes. However, the effects of acute experimental alterations to the force vector orientation within athletes are unknown. Fifteen male team sports athletes completed maximal effort 10-m accelerations in three conditions following different verbal instructions intended to manipulate the force vector orientation. Ground reaction forces (GRFs) were collected from the step nearest 5-m and stance leg kinematics at touchdown were also analysed to understand specific kinematic features of touchdown technique which may influence the consequent force vector orientation. Magnitude-based inferences were used to compare findings between conditions. There was a likely more horizontally oriented ground reaction force vector and a likely lower peak vertical force in the control condition compared with the experimental conditions. 10-m sprint time was very likely quickest in the control condition which confirmed the importance of force vector orientation for acceleration performance on a within-athlete basis. The stance leg kinematics revealed that a more horizontally oriented force vector during stance was preceded at touchdown by a likely more dorsiflexed ankle, a likely more flexed knee, and a possibly or likely greater hip extension velocity.
authors.affiliation: a Applied Sports, Technology, Exercise and Medicine Research Centre , Swansea University , Swansea , UK.|b School of Sport, Health and Applied Science , St Mary's University , Twickenham , UK.
authors.forename: Neil E
authors.initials: NE
authors.lastname: Bezodis
authors.affiliation: b School of Sport, Health and Applied Science , St Mary's University , Twickenham , UK.
authors.forename: Jamie S
authors.initials: JS
authors.lastname: North
authors.affiliation: b School of Sport, Health and Applied Science , St Mary's University , Twickenham , UK.
authors.forename: Jane L
authors.initials: JL
authors.lastname: Razavet
mesh_terms: D000054:Acceleration; D054874:Athletic Performance / Q000502:physiology*; D001696:Biomechanical Phenomena; D005684:Gait / Q000502:physiology; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D011187:Posture / Q000502:physiology; D012420:Running / Q000502:physiology*; D013647:Task Performance and Analysis; D055815:Young Adult
keywords: Attentional focus; biomechanics; ratio of forces; sprinting; technique