title: Comparison of acute countermovement jump responses after functional isometric and dynamic half squats.
abstract: The purpose of this study was to compare acute countermovement jump (CMJ) responses after functional isometric (FI) and dynamic half (DH) squats. Ten strength-trained males (relative full back squat 1 repetition maximum [1RM]: 1.9 ± 0.2) participated in a randomized crossover design study. On 2 separate days, participants performed baseline CMJs followed by either FI or DH squats loaded with 150% of full back squat 1RM. Further CMJs were performed between 2 and 11 minutes after FI or DH squats. Kinematic and kinetic CMJ variables were measured. There were no differences observed between conditions when peak CMJ variables after FI or DH squats were compared with baseline values (p > 0.05). Countermovement jump time effects (p ≤ 0.05) were observed after squats. Increases in peak force (p ≤ 0.05; FI: 3.9%, range: -0.9 to 9.1%; DH: 4.2%, range: 0.0-11.5%) and decreases in peak power (p ≤ 0.05; FI: -0.4%, range: -5.1 to 4.0%; DH: -1.1%, range: -6.6 to 2.9%) occurred for combined condition data. Positive correlations between lower-body strength and the extent or timing of acute CMJ responses were not detected (p > 0.05). Because of the apparent lack of additive acute CMJ responses, the use of conventional DH squat protocols should be considered rather than FI squats in precompetition and training situations. Furthermore, the establishment of individual FI and DH squat protocols also seems to be necessary, rather than relying on relative lower-body strength to predict the nature of acute CMJ responses.
authors.affiliation: 1The Moray House School of Education, Institute for Sport, Physical Education, and Health Sciences, University of Edinburgh, Edinburgh, United Kingdom; 2SportScotland Institute of Sport, Stirling, United Kingdom; 3School of Sport, Exercise, and Health Sciences, Loughborough University, Loughborough, United Kingdom; and 4Health and Exercise Sciences Research Group, University of Stirling, Stirling, United Kingdom.
authors.forename: David A
authors.initials: DA
authors.lastname: Boyd
authors.forename: Neil
authors.initials: N
authors.lastname: Donald
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Balshaw
mesh_terms: D000328:Adult; D001415:Back / Q000502:physiology; D001696:Biomechanical Phenomena; D018592:Cross-Over Studies; D006801:Humans; D007700:Kinetics; D035002:Lower Extremity / Q000502:physiology; D008297:Male; D009068:Movement / Q000502:physiology*; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000502:physiology*; D011897:Random Allocation; D055070:Resistance Training / Q000379:methods*; D055815:Young Adult