title: The effects of barbell load on countermovement vertical jump power and net impulse.
abstract: The aim of this study was to examine the effects of barbell load on countermovement vertical jump (CMJ) power and net impulse within a theoretically valid framework, cognisant of the underpinning force, temporal, and spatial components. A total of 24 resistance-trained rugby union athletes (average ± SD: age: 23.1 ± 3.4 years; height: 1.83 ± 0.05 m; body mass (BM): 91.3 ± 10.5 kg) performed maximal CMJ under 5 experimental conditions in a randomised, counterbalanced order: unloaded, and with additional loads of 25%, 50%, 75%, and 100% of BM. Peak power and average power were maximised during the unloaded condition, both decreasing significantly (P < 0.05) as load increased. Net impulse was maximised with 75% of BM, which was significantly greater (P < 0.05) than the unloaded and 100% of BM conditions. Net mean force and mean velocity were maximised during the unloaded condition and decreased significantly (P < 0.05) as load increased, whereas phase duration increased significantly (P < 0.05) as load increased. As such, the interaction between barbell load and the underpinning force, time, and displacement components should be considered by strength and conditioning coaches when prescribing barbell loads.
authors.affiliation: a Department of Sport and Exercise Sciences , University of Chichester , Chichester , UK.|b Department of Applied Sciences and health , Coventry University , Coventry , UK.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Mundy
authors.affiliation: a Department of Sport and Exercise Sciences , University of Chichester , Chichester , UK.
authors.forename: Neal A
authors.initials: NA
authors.lastname: Smith
authors.affiliation: a Department of Sport and Exercise Sciences , University of Chichester , Chichester , UK.
authors.forename: Mike A
authors.initials: MA
authors.lastname: Lauder
authors.affiliation: a Department of Sport and Exercise Sciences , University of Chichester , Chichester , UK.
authors.forename: Jason P
authors.initials: JP
authors.lastname: Lake
mesh_terms: D001696:Biomechanical Phenomena; D005538:Football / Q000502:physiology; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D064797:Physical Conditioning, Human / Q000379:methods*; D059385:Plyometric Exercise; D014891:Weight Lifting / Q000502:physiology*; D016474:Weight-Bearing; D055815:Young Adult
keywords: Kinetics; force; kinematics; optimal load; performance