A biomechanical comparison of controlled versus explosive back squats
- Authors: Young, Warren , O'Grady, Mathew
- Date: 2014
- Type: Text , Journal article
- Relation: Journal of Australian Strength and Conditioning Vol. 22, no. 5 (2014), p. 87-90
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A comparison of Smith machine and barbell half squats to elicit potentiation in countermovement jump performance
- Authors: O'Grady, Mathew , Young, Warren , Talpey, Scott
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Australian Strength & Conditioning Vol. 23, no. 6 (2015), p. 90-94
- Full Text: false
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- Description: The article presents a study which compares the post activation potentiation (PAP) of Smith machine & barbell (BB) half squats in countermovement jump (CMJ) performance. It explores the different force output and muscle activation between the two different squatting methods in jumping performance. It shows repeated measures of ANOVA revealing a significant squat type by time interaction for the best peak power, indicating that CMJ is greater in Smith machine squat than the BB squat.
Acute increases in performance: Post-activation potentiation or general warm-up effects:? A review of the literature
- Authors: O'Grady, Mathew , Young, Warren
- Date: 2013
- Type: Text , Journal article
- Relation: Journal of Australian Strength and Conditioning Vol. 21, no. S2 (2013), p. 91-93
- Full Text: false
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Discriminative ability of lower limb strength and power measures in lacrosse athletes
- Authors: Talpey, Scott , Axtell, Robert , Gardner, Elizabeth , Maloney, Maggie , Newman, Thomas , Cordone, Jason , O'Grady, Mathew
- Date: 2023
- Type: Text , Journal article
- Relation: International Journal of Sports Medicine Vol. 44, no. 1 (2023), p. 29-37
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- Description: The objective of this investigation was to compare isokinetic strength, countermovement jump and drop jump variables between high-contributors and low-contributors within NCAA Division I Men's and Women's lacrosse athletes. Men's (N=36) and Women's (N=30) NCAA Division I lacrosse athletes completed strength testing of the quadriceps and hamstring across three speeds (60°·s -1, 180°·s -1, 300°·s -1), countermovement and drop jumps. To determine the discriminative ability of select lower-limb strength and power characteristics participants were categorized as high-contributors (Males N=18, age=20.3±0.4 yrs, height=183.9±5.5 cm, mass=90.8±5.8 kg; Females N=15, age=20.8±0.8 yrs, height=169.3±6.7 cm, mass=64.1±7.2 kg) or low-contributors (Males N=18, age=19.5±0.2 yrs, height=184.1±5.6 cm; mass=87.9±8.1 kg; Females N=15, age=19.7±0.2 yrs, height=169.8±7.0 cm, mass=62.9±7.7 kg) based upon the number of games the participants competed in during the regular season. Within the male cohort, moderate significant (p<0.05) differences were observed between high-contributors and low-contributors in isokinetic hamstring strength of the left leg at 300°·s -1(d=0.69) and peak power in countermovement jump (d= 0.68). Within the women's cohort a large (d= 0.87) significant difference (p<0.05) in isokinetic strength of the left hamstring was observed between high-contributors and low-contributors at 60°·s -1. Hamstring strength and lower-limb power are important strength measures for lacrosse performance and should be prioritized in training prescription for lacrosse athletes. © 2023 Georg Thieme Verlag. All rights reserved.
Does the warm-up effect subsequent post activation performance enhancement?
- Authors: O'Grady, Mathew , Young, Warren , Talpey, Scott , Behm, David
- Date: 2021
- Type: Text , Journal article
- Relation: The Journal of Sport and Exercise Science Vol. 5, no. 4 (SESN 2021), p.
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- Description: The purpose of the following study was first to identify an optimal warm-up to maximise countermovement jump (CMJ) performance, and second to investigate whether a conditioning activity (CA) of half-squats could potentiate CMJ performance above that of the optimal warm-up. Sixteen resistance trained males were recruited for the study. Participants performed six different warm-up volumes over six sessions. Warm-ups consisted of submaximal running, dynamic stretching and practice CMJs. After the warmup, participants rested for four minutes before performing three CMJs on a force platform. The warm-up which resulted in the best CMJ relative peak power (RPP) was considered to be that individual’s optimal warm-up. Participants attended another testing session where they performed their optimum warm-up followed by a pre-CMJ test. Participants then performed a CA of four half-squats with a 5RM load followed by post-CMJ tests after fourand eight-minutes recovery. No CMJ variable displayed significant improvements at either four or eight minutes recovery after the CA when compared to the pre-test. However, when everyone’s optimum recovery period was considered, CMJ height significantly improved by 5.2% (p = 0.009) when compared with pre-CMJ performance. If the optimum recovery period is considered, a half-squat CA can further mprove CMJ height above that of a general warm-up alone
Effect of intention to squat explosively on acute countermovement jump performance
- Authors: O'Grady, Mathew , Young, Warren , Behm, David , Talpey, Scott
- Date: 2021
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 35, no. 12 (2021), p. 3348-3354
- Full Text: false
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- Description: Effect of intention to squat explosively on acute countermovement jump performance. J Strength Cond Res 35(12): 3348-3354, 2021 - The purpose of this study was to investigate the influence of squatting with the intention of moving the bar as fast as possible during the ascent phase on potentiating countermovement jump (CMJ) performance. Fourteen recreationally resistance-trained men (age = 22.1 ± 1.7 years, height = 179.9 ± 4.2 cm, body mass = 83.8 ± 6.6 kg) with a predicted 1 repetition maximum half-squat of 201.0 ± 27.8 kg participated in this study. Subjects performed 3 CMJs before and then 4 and 8 minutes after a squat conditioning activity (CA). Conditions were randomized. For 1 condition, the CA involved subjects performing 4 repetitions of the half-squat with a 5RM load in a controlled manner (CON) at a self-selected normal squatting tempo. In the other condition, subjects used the same number of repetitions and load; however, they were instructed to move the bar up as fast as possible during the concentric phase of the half-squat (VMAX). Half-squat peak force (N), peak power (W), peak velocity (m·s-1), and rate of force development (RFD) were measured for each CA using a force platform and linear position transducer. At 4 and 8 minutes post-CA, CMJ height, relative peak power, peak velocity, and peak force were also measured. Despite there being significant increases in the half-squat peak power, peak velocity and maximum RFD in the VMAX condition, neither condition significantly improved any post-CMJ variable. Some small improvements in jump height were observed in certain individuals after the VMAX condition, suggesting that an explosive half-squat CA may potentiate CMJ performance in certain individuals. © 2020 National Strength and Conditioning Association.
Lower body exercise selection across the force-velocity continuum to enhance sprinting performance
- Authors: Young, Warren , Talpey, Scott , Feros, Simon , O'Grady, Mathew , Radford, Christopher
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Australian Strength and Conditioning Vol. 23, no. (2015), p. 39-42
- Full Text: false
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- Description: BLUF Training for the speed component of sprinting with resistance training requires the use of high velocity horizontally-directed exercises such as speed-bounding and sled sprinting. ABSTRACT The purpose of this article was to evaluate selected resistance training exercises in relation to the force-velocity continuum, with the application to sprinting performance in team sport athletes. The analysis of exercises was done by focussing on the peak velocities reached and comparing this to velocities in sprinting. Many popular resistance training exercises such as jump squats and modifications of the Olympic lifts are used to enhance the explosive muscle qualities required for sprinting. A common characteristic of these exercises is that force application and corresponding body/bar movement is directed vertically upward against gravity. This means that despite using light loads or no extra load, the resulting movements are relatively slow (less than 5 s-1). For example, adding any load to jump squats generally decreases power output compared to jumps with only bodyweight. Therefore, vertically-directed exercises should be considered as being strength-dominated. However, sprinting involves relatively short muscular contractions and considerably faster movement, even over short distances of less than 20 m. To prescribe exercises that are closer to the speed end of the force-velocity continuum, horizontally directed exercises are preferable. Examples include sled sprints and plyometric exercises such as speed-bounding. In a periodised program designed to enhance sprinting performance, vertical exercises such as jump squats and power cleans should be considered as strength-dominated, whereas horizontal exercises should be prescribed when speed qualities need to be emphasised such as in a pre-competition phase.
- Description: BLUF Training for the speed component of sprinting with resistance training requires the use of high velocity horizontally-directed exercises such as speed-bounding and sled sprinting. ABSTRACT The purpose of this article was to evaluate selected resistance training exercises in relation to the force-velocity continuum, with the application to sprinting performance in team sport athletes. The analysis of exercises was done by focussing on the peak velocities reached and comparing this to velocities in sprinting. Many popular resistance training exercises such as jump squats and modifications of the Olympic lifts are used to enhance the explosive muscle qualities required for sprinting. A common characteristic of these exercises is that force application and corresponding body/bar movement is directed vertically upward against gravity. This means that despite using light loads or no extra load, the resulting movements are relatively slow (less than 5 m
Manipulating a conditioning activity to enhance potentiation and its application to jumping and sprinting performance
- Authors: O'Grady, Mathew
- Date: 2017
- Type: Text , Thesis , PhD
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- Description: 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.
- Description: Doctor of Philosophy
The occurrence of different vertical jump types in basketball competition and their relationship with lower-body speed-strength qualities
- Authors: Talpey, Scott , Smyth, Andrew , O'Grady, Mathew , Morrison, Matthew , Young, Warren
- Date: 2021
- Type: Text , Journal article
- Relation: International Journal of Strength and Conditioning Vol. 1, no. 1 (2021), p.
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- Description: Jumps occur frequently in basketball and can be executed from a single-leg take-off following a run-up or bilaterally from a standing start. Understanding the type of jumps performed in competition and how different muscular qualities influence their performance, informs training prescription. Firstly, to quantify the occurrence of different jump types performed in competition an analysis of 15 semi-professional basketball games was undertaken. Secondly, to understand the influence of muscular qualities on performance of different jump types, Semi-professional male basketball players (N=17) performed jump tests standing vertical jump, running vertical jumps with a double leg take-off (RVJ2) and a single leg take-off (RVJ1) and tests of lower-body speed-strength reactive strength index (RSI) from a drop jump, counter movement jump (CMJ) and squat jump. A stationary approach was employed for 69%, a running approach for 26% and a one-step approach for 5%. RVJ1 displayed non-significant (P=0.07) moderate correlation with jump height attained from the CMJ (r=0.439) and a very large (r =.806) significant (P<0.01) correlation with RSI. Most jumps were executed from a stationary start with a bilateral take-off while a run-up occurred prior to a substantial proportion of jumps. Jumps with a single-leg take-off from a run-up strongly correlate with RSI.