Manipulating a conditioning activity to enhance potentiation and its application to jumping and sprinting performance

- O'Grady, Mathew

Title
Manipulating a conditioning activity to enhance potentiation and its application to jumping and sprinting performance
Creator
O'Grady, Mathew
Date
2017
Type
Text; Thesis; PhD
Identifier
http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/165480
Identifier
vital:13317
Identifier
https://library.federation.edu.au/record=b2752646
Abstract
Post-activation potentiation (PAP) is the phenomenon where contractile history of a muscle may acutely increase voluntary performance of future contractions that are biomechanically similar (72). In order to exploit the PAP phenomenon, a conditioning activity (CA) is performed to enhance the performance of a subsequent skill. Throughout the literature, a common example of a CA is sets of heavy-loaded squats in order to potentiate subsequent jumping (31,33,39,57,83,116,151,163) or sprinting performance (15,28,39,99). Post-activation potentiation can be used either in a warm-up to acutely enhance performance for competition, or used within a resistance training session to enhance speed-strength, with the intention of producing a greater training stimulus for chronic adaptations. The major issue with the PAP literature is the inconsistent results from study to study. There are many examples within the research that show the positive effects of PAP (44,54,57,62,83,102,133,163), whilst many others have failed to find any increase in performance (42,47,56,81,112,123,141). The results have been inconsistent as the methodology between studies has varied dramatically. These differences include the warm-up used prior to testing sessions, changes in the type of CA (30,54,163), the intensity or load of the CA (19,21,33) and the rest period allocated between the CA and the performance of the skill. Furthermore, it seems that certain individuals respond better to a CA, with most of the literature suggesting that participant strength has a positive correlation with a potentiating response (15,31,44,116,128,129,163). Due to the vast differences in methodologies used throughout the potentiation literature, it is hard for coaches to identify the best practice in order to elicit a positive potentiating effect. Therefore, four studies were designed to address these current gaps within the potentiation literature in order to establish the best methodology to elicit a potentiating response. The first study sought to investigate whether a heavy half-squat CA could further improve jumping after an individualised optimal warm-up. As many of the warm-ups used prior to the baseline measurement in the potentiation research have been insufficient (30,44,69,71,88,102,111,115,140,143,158), it is plausible to suggest that improvements after a CA could be due to general mechanisms of a warm-up, rather than PAP. To investigate this, participants performed six different volumes of warm-ups on six separate days, followed by CMJ and DJ testing. After each participant completed the six warm-ups, their individual optimum warm-up was identified as the warm-up that produced the greatest CMJ relative peak power (RPP). On two separate sessions, a CA of four half-squats at a 5RM load was then added to each individual’s optimum warm-up and a sub-optimum warm-up. Countermovement jump tests were performed before the CA (pre) and then four and eight minutes after the CA. Drop jump testing was performed before the CA (pre) and then six and 10 minutes after the CA. When examining each post-test separately, no improvements in CMJ performance were identified. Furthermore, for both the optimum and sub-optimum warm-up conditions, DJ performance significantly decreased at all post-tests (p < 0.05). When each individuals best recovery period was considered (post-best), both the maximum and mean CMJ jump height significantly increased above baseline measures for the optimum warm-up condition. No other CMJ or DJ variable displayed any significant change after the addition of the CA for either condition. As significant increases in CMJ jump height were identified, the four half-squat CA with a 5RM load was used in the next investigation. Although each individual’s optimum warm-up volume varied, the moderate warm-up volume produced sufficient CMJ performance for all individuals. Considering the time required identifying each individuals optimum warm-up, the moderate warm-up was deemed sufficient and was used for the following studies. The second study of this thesis investigated the acute response of two different CA strategies. Both CAs included four half squats at a 5RM load, however, in one condition participants were instructed to perform the squat in a controlled manner, whilst in the second condition, they were instructed to lift the bar as fast as possible without losing contact with the ground. At any post-time (including post-best), no significant improvement were identified for any CMJ variable in either condition. Furthermore, DJ performance significantly decreased at all post-tests for the explosive CA condition. Although no significant improvements were identified, when each individual’s optimum recovery period was considered, CMJ jump height increased by 2.6% in the explosive CA condition, as opposed to 0.9% in the controlled CA condition. Because of this difference within the means of each condition, for the future studies throughout this thesis, participants were instructed to lift the bar as fast as possible during a heavy half-squat CA. The third study of this thesis compared different volumes of plyometric CAs (rebound jumps) to a CA involving heavy half-squats and assessed the effect each had on potentiating CMJ and sprinting performance. Past research had often used small amounts of plyometric contacts to potentiate future contractions (23,30,143,146,151), however, due to their short duration; they were often not successful in improving performance. For one condition, this study increased the repetitions of plyometric contacts in the CA, so that its duration matched the time under tension exhibited by the four half-squats with a 5RM load. Furthermore, two other plyometric CA conditions were included; one that matched half of the time under tension of the half-squats and one that involved only four repetitions of the rebound jump (match the amount of repetitions of the half-squat). No CA (plyometric or half-squat) displayed statistical significant improvements in CMJ or sprint performance at any post-test interval. For CMJ performance, although it did not significantly improve performance, generally the heavy half-squat CA had smaller decrements in performance than the plyometric CAs, hence the final investigation of this thesis focussed upon different heavy dynamic CAs in order to potentiate CMJ performance. The final study of this thesis firstly aimed to investigate the effect of three different types of half-squat CAs had on potentiating CMJ performance. This study also aimed to explore why certain individuals respond positively to a CA, whilst others respond in a negative manner. At the beginning of this study, participants completed a number of fitness performance tests, to assess each individual’s performance. Participants then assessed the effect of three different CAs on CMJ performance. These CAs included three repetitions of the half-squat with a 3RM load (3 @ 3RM), four repetitions with a 5RM load (4 @ 5RM) and then five repetitions with a 5RM load (5 @ 5RM). In terms of the entire population of the study, after each of the CAs, post-CMJ performance typically decreased across all rest periods, whilst any improvement in particular CMJ variables were considered to only be trivial in terms of effect size magnitudes. Despite this, multiple statistically significant positive correlations were evident between particular fitness qualities (absolute strength, CMJ RPP and aerobic capacity) and the change scores between pre and post-best CMJ performance after certain CAs. Therefore, the participants were median split in terms of each of the following fitness qualities to assess the relationship each quality has on potentiating CMJ performance. When the population was split in terms of absolute strength, the stronger participants significantly improved CMJ performance at their best recovery period after the performance of the 5 @ 5RM CA (three out of the four CMJ variables assessed significantly improved), whilst the weaker individuals showed no significant improvements. A similar trend was exhibited when the population was split in terms of CMJ RPP, with the more powerful individuals improving by small to moderate effect size magnitudes after the 5 @ 5RM CA, whilst the less powerful group did not. From the studies presented in the thesis, it can be concluded that certain recreationally resistance trained males can acutely enhance CMJ performance with the use of a heavy dynamic CA, even after pre-test performance has been optimised by a general warm-up. The optimum recovery period for the individual does need to be considered, as individuals require different amounts of rest to allow for an improvement in performance. Furthermore, the individual needs to have sufficient strength of the lower limbs in order to improve future contractions via the use of the heavy dynamic CA, as individuals with less strength do not improve post-CMJ performance after a CA. In terms of the type of CA used, heavy half-squat seem to be more effective than rebound jumps in order to potentiate CMJ performance. Furthermore, five repetitions with a 5RM load seems more effective than heavier CAs (3 @ 3RM) or ones that have less repetitions (4 @ 5RM) for this particular population.; Doctor of Philosophy
Publisher
Federtion University Australia
Rights
Copyright Mathew O'Grady
Rights
Open Access
Rights
This metadata is freely available under a CCO license
Subject
Conditioning activity; Jumping performance; Sprinting performance; Post-activation potentiation
Full Text
Thesis Supervisor
Young, Warren
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