Have the benefits of lower body nonballistic resistance exercises been underestimated?

Austin, Kieran (2016) Have the benefits of lower body nonballistic resistance exercises been underestimated? Undergraduate thesis, University of Chichester.

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Abstract

Research shows that traditional methods of identifying the propulsion phase of non-ballistic exercises may underestimate their kinetic and kinematic benefits, overemphasising the superiority of ballistic exercises for power development training. Aims: The aims of the study were to compare the differences between ballistic jump squat (JS) and non ballistic back squat (BS) mean force, velocity, power, and propulsion phase time, and the effect the method used to identify the propulsion phase had on these variables over a range of loads. Methods: Ground reaction forces (GRF) were recorded at 1000 Hz from 12 active men, completing four single repetitions with 30%, 45%, 60% and 75% of 1RM for both JS and BS exercises. System weight was subtracted from GRF data to obtain net force; net force divided by mass to gain acceleration; acceleration multiplied by time to gain velocity; and force was multiplied by velocity to obtain power. Displacement was obtained by multiplying velocity by time. Force, velocity and power were averaged over the propulsion phase. This was identified as starting from the lowest displacement to either peak displacement (PD) or peak velocity (positive acceleration [PA]). Results: When identified using PD, JS showed significantly greater mean power with 30%-75% 1RM and mean velocity with 45%-75% 1RM compared to BS. There was no difference in mean force. When identified using PA, JS showed significantly greater power, velocity and force with 30%-75% 1RM compared to BS. Importantly, PD underestimated BS power by an average of 16% and BS force by 18%, but did not effect velocity. Conclusions: JS is shown to be superior in terms of velocity and power production, and should therefore be the primary exercise used to develop these attributes. The method used to identify the propulsion phase appears to dramatically alter both force and power outputs for both exercises; whilst also changing the characteristics of the load-power relationship and optimal load. Results therefore emphasise the importance of valid strategies for identifying the propulsion phase.

Item Type: Thesis (Undergraduate)
Additional Information: BSc (Hons) Sport & Exercise Science (Sports Performance)
Subjects: Q Science > Q Science (General)
Divisions: Departments > Sport and Exercise Sciences
Undergraduate Dissertations
Depositing User: Ann Jones
Date Deposited: 20 Sep 2016 09:12
Last Modified: 20 Sep 2016 09:12
URI: http://eprints.chi.ac.uk/id/eprint/1972

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