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Journal of Strength & Conditioning Research:
doi: 10.1519/JSC.0000000000000559
Original Investigation: PDF Only

A Comparison of Acute Countermovement Jump Responses Following Functional Isometric and Dynamic Half Squats.

Boyd, David A.; Donald, Neil; Balshaw, Thomas G.

Published Ahead-of-Print
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The purpose of this study was to compare acute CMJ responses following functional isometric (FI) and dynamic half (DH) squats. Ten strength-trained males (relative full back squat one repetition maximum (1RM): 1.9 +/- 0.2) participated in a randomized crossover design study. On two 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 min after FI or DH squats. Kinematic and kinetic CMJ variables were measured. There were no differences observed between conditions when peak CMJ variables following FI or DH squats were compared to baseline values (p > 0.05). CMJ time effects (p < 0.05) were observed following squats. Increases in peak force (p < 0.05; FI: 3.9%, range: -0.9-9.1%; DH: 4.2%, range: 0.0-11.5%) and decreases in peak power (p < 0.05; FI: -0.4%, range: -5.1-4.0%; DH: -1.1%, range: -6.6-2.9%) 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). Due to the apparent lack of additive acute CMJ responses, the use of conventional DH squat protocols should be considered rather than FI squats in pre-competition and training situations. Furthermore, the establishment of individual FI and DH squat protocols also appears to be necessary, rather than relying on relative lower-body strength to predict the nature of acute CMJ responses.

Copyright (C) 2014 by the National Strength & Conditioning Association.



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