Can backward sled towing potentiate five metre sprint performance? : a thesis presented in partial fulfilment of the requirements for the degree of Master of Sport and Exercise at Massey University, Palmerston North, New Zealand
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Date
2019
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Massey University
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Abstract
Post-activation potentiation (PAP) describes an augmentation within muscle properties, with the ability to enhance muscular performance. Due to the complexity of this highly individualised phenomenon, PAP has the greatest effect in well-trained populations. Back squat, sled towing, and sled pushing protocols have shown to acutely improve 20 m sprint performance. Potentiating activities that reflect the specific movement profiles of the performance activity are proposed as most effective, suggesting a possible relationship between muscle specific potentiation and augmented sprint performance. Therefore, the use of a quadriceps dominant sprint related exercise (i.e., backward sled towing) may acutely enhance sprint performance.
The objectives of this study were to determine whether backward sled towing can elicit a PAP response to enhance 5 m sprint performance, and to determine if sled loading via a reduction in velocity can elicit an improvement in 5 m sprint performance. A randomised design was used to examine the effects of forward and backward sled tow loading of 35% and 55% reduction of individual’s maximal velocity (rVelmean) on 5 m sprint performance. Eighteen participants performed one familiarisation session, followed by four intervention sessions (55% rVelmean backward; 55% rVelmean forward; 35% rVelmean backward; 35% rVelmean forward) separated by a minimum of 24-hours. Intervention sessions included baseline un-resisted 5 m sprints, and the collection of maximum voluntary contractions of lower limb musculature via surface electromyography (EMG), followed by three loaded sled tows over a distance of 3.2 m or 5 m for heavy and light loads, respectively. An un-resisted 5 m sprint was then completed following 6 and 12 min rest. Mean sprint velocity, EMG, and sprint kinematic and temporal data were collected during each session. EMG was used to determine if a potentiated effect was due to changes in neural excitation.
Sled towing, irrespective of load or rest period, produced no significant change in 5 m sprint velocity (p > 0.05). Significant difference was found between both 35% and 55% backwards calculated velocity reduction and actual velocities during towing (p < 0.01). There was no significant change in EMG across sessions. Kinetic and temporal data suggested no significant changes in baseline measures; however, current findings highlight the importance of vertical force production during sprint acceleration.
Sled towing to potentiate sprint performance using a reduction of velocity requires further investigation. The author acknowledges that greater time under tension during conditioning activities may result in greater sprint related potentiation. However, further research is required to assess the legitimacy of this speculation.
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Figure 1 (=Chang et al., 2016 Fig 3) was removed for copyright reasons.
Keywords
Sprinting, Physiological aspects, Muscles, Physiology, Weight training