Resistance training for short sprints and maximum-speed sprints
- Young, Warren, Benton, Dean, Duthie, Grant, Pryor, John
- Authors: Young, Warren , Benton, Dean , Duthie, Grant , Pryor, John
- Date: 2001
- Type: Text , Journal article
- Relation: Strength and Conditioning Journal Vol. 23, no. 2 (2001), p. 7-13
- Full Text:
- Reviewed:
- Authors: Young, Warren , Benton, Dean , Duthie, Grant , Pryor, John
- Date: 2001
- Type: Text , Journal article
- Relation: Strength and Conditioning Journal Vol. 23, no. 2 (2001), p. 7-13
- Full Text:
- Reviewed:
Specificity of sprint and agility training methods
- Young, Warren, McDowell, Mark, Scarlett, Bentley
- Authors: Young, Warren , McDowell, Mark , Scarlett, Bentley
- Date: 2001
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 15, no. 3 (2001), p. 315-319
- Full Text:
- Reviewed:
- Description: The purpose of this study was to determine if straight sprint training transferred to agility performance tests that involved various change-of-direction complexities and if agility training transferred to straight sprinting speed. Thirty-six males were tested on a 30-m straight sprint and 6 agility tests with 2-5 changes of direction at various angles. The subjects participated in 2 training sessions per week for 6 weeks using 20-40-m straight sprints (speed) or 20-40-m change-of-direction sprints (3-5 changes of 100°) (agility). After the training period, the subjects were retested, and the speed training resulted in significant improvements (p < 0.05) in straight sprinting speed but limited gains in the agility tests. Generally, the more complex the agility task, the less the transfer from the speed training to the agility task. Conversely, the agility training resulted in significant improvements in the change-of-direction tests (p < 0.05) but no significant improvement (p > 0.05) in straight sprint performance. We concluded that straight speed and agility training methods are specific and produce limited transfer to the other. These findings have implications for the design of speed and agility training and testing protocols.
- Description: 2003003767
- Authors: Young, Warren , McDowell, Mark , Scarlett, Bentley
- Date: 2001
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 15, no. 3 (2001), p. 315-319
- Full Text:
- Reviewed:
- Description: The purpose of this study was to determine if straight sprint training transferred to agility performance tests that involved various change-of-direction complexities and if agility training transferred to straight sprinting speed. Thirty-six males were tested on a 30-m straight sprint and 6 agility tests with 2-5 changes of direction at various angles. The subjects participated in 2 training sessions per week for 6 weeks using 20-40-m straight sprints (speed) or 20-40-m change-of-direction sprints (3-5 changes of 100°) (agility). After the training period, the subjects were retested, and the speed training resulted in significant improvements (p < 0.05) in straight sprinting speed but limited gains in the agility tests. Generally, the more complex the agility task, the less the transfer from the speed training to the agility task. Conversely, the agility training resulted in significant improvements in the change-of-direction tests (p < 0.05) but no significant improvement (p > 0.05) in straight sprint performance. We concluded that straight speed and agility training methods are specific and produce limited transfer to the other. These findings have implications for the design of speed and agility training and testing protocols.
- Description: 2003003767
- Robbins, Daniel, Young, Warren
- Authors: Robbins, Daniel , Young, Warren
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 26, no. 2 (2012), p. 388-397
- Full Text: false
- Reviewed:
- Description: The purpose of this study was to investigate positional relationships between sprint and jump abilities and body mass in elite college American football players (n = 1,136). Data from the annual National Football League combine over the years 2005-2009 were examined. The measures included for examination were the 9.1-, 18.3-, 36.6-, and flying 18.3-m sprints and the vertical and horizontal jumps. Pearson's correlation coefficients (r) were calculated to determine the relationships between the tests, and coefficients of determination (r2) were used to determine common variance. With the exception of the relationship between the 9.1-m and the flying 18.3-m sprints, the relationships between all sprints are very strong. Vertical jump ability is more strongly associated with maximum speed, as compared with acceleration. Horizontal jump ability is similarly associated with maximum speed and acceleration. The 9.1-, 18.3-, and flying 18.3-m sprints and the jump tests would appear to measure independent skills. Stationary start sprints up to 36.6 m appear to be heavily influenced by acceleration and may thus measure similar characteristics. The flying 18.3-m sprint is recommended as a measure of maximum speed. Body mass was most strongly associated with performance in the lineman group. When body mass was controlled for, correlations weakened across all the groups. The role of body mass remains unclear. Regardless of sport, the present research supports the notion that the relationships between various sprint and jump abilities warrant positional consideration. Coaches and practitioners will be able to use the findings of this research to better test and monitor athletes requiring different skills. © 2012 National Strength and Conditioning Association.
Comparison of playing positions in elite Australian football: A case study of one club
- Young, Warren, Burge, Peter, Russell, Andrew, Carlon, Todd
- Authors: Young, Warren , Burge, Peter , Russell, Andrew , Carlon, Todd
- Date: 2010
- Type: Text , Journal article
- Relation: Journal of Australian Strength and Conditioning Vol. 18, no. 4 (2010), p. 11-13
- Full Text: false
- Reviewed:
- Description: Previous research using Global Positioning Systems (GPS) to track Australian football (AF) games has used a 1 Hz sampling rate and limited variables to describe game demands. The aim of this study was to compare midfielders and forwards/backs from one elite Australian football club via GPS tracking of games. Game files (n=100) were collected from 19 players (14 midfielders, 5 forwards/backs) and the total distance covered at various speed and acceleration/deceleration zones was analysed. Player positions were statistically compared by one-way ANOVA. Midfielders covered a greater total distance and distance at running speeds between 4-7 m.s. (p<0.05), whereas forwards/backs produced slightly greater maximum running speeds, greater distance sprinting at speeds over 7 m.s, and greater distance peforming high accelerations (p>0.05). The movement demands for midfielders tended towards moderate to fast running speeds whereas forwards/backs displayed a greater proportion of their distance covered at high speed and acceleration/deceleration. It is suggested from the GPS variable that used conditioning should be somewhat indidvidualised to match the specific demands of the playing positions.
- Description: C1
- Young, Warren, Grace, Steve, Talpey, Scott
- Authors: Young, Warren , Grace, Steve , Talpey, Scott
- Date: 2014
- Type: Text , Journal article
- Relation: International Journal of Sports Science & Coaching Vol. 9, no. 5 (2014), p. 1153-1160
- Full Text: false
- Reviewed:
- Description: The main purpose of this study was to determine the association between leg power and sprint technique with 20-m sprint performance. Seventy- seven elite junior Australian Rules football players were assessed on a 20-m sprint test, a countermovement jump (CMJ) and a two bound test, and on a new method of quantifying sprint technique from simple video recordings. Technique assessment involved rating 14 points on a scale from 1-5. Players were median-split into faster and slower groups based on their 20-m times, and they were compared for differences in leg power and technique. The faster group was significantly better (p<0.05) in the two-bound test (5.2%) and the technique score (8.2%), but not in the CMJ (p>0.05). A multiple regression indicated that the two-bound test and technique accounted for 37.7% of the variance associated with the 20-m sprint time (p<0.05). It was concluded that the technique assessment tool captured some important characteristics of 20-m sprint performance and could potentially be used to profile or monitor athletes. Further the two-bound test is a more relevant test for developing athletes because of its specificity to sprinting, compared to the CMJ. ABSTRACT FROM AUTHOR
Lower body exercise selection across the force-velocity continuum to enhance sprinting performance
- Young, Warren, Talpey, Scott, Feros, Simon, O'Grady, Mathew, Radford, Christopher
- 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
- Reviewed:
- 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
Salivary hormone response to maximal exercise at two time points during the day
- Hayes, Lawrence, Grace, Fergal, Kilgore, Lon, Young, John, Baker, Julien
- Authors: Hayes, Lawrence , Grace, Fergal , Kilgore, Lon , Young, John , Baker, Julien
- Date: 2013
- Type: Text , Journal article
- Relation: Sport SPA Vol. 10, no. 1 (2013), p. 25-30
- Full Text: false
- Reviewed:
- Description: The aim of the present study was to establish a relationship between the diurnal variations of testosterone and cortisol with the circadian rhythm of strength and power performance. Changes in salivary cortisol and salivary testosterone were measured after two different modes of maximal exercise (back squat and maximal 5 m sprint) at two different times of day to assess diurnal fluctuations. Seventeen physically active males volunteered as subjects. A randomized cross-over design was utilized and participants were allocated to a maximal back squat protocol at 09:00 and 17:00 h, and a maximal 5 m sprint protocol at 09:00 and 17:00 h separated by at least 48 h. Saliva samples were collected before exercise, at 5 and 60 min post exercise. Exercise performance displayed no time of day effect. No significant effect of exercise mode or time of day was observed in cortisol or testosterone concentrations. Cortisol concentrations were higher in the morning (p<0.001). Testosterone did not exhibit a significant time of day effect however, higher levels tended to be observed at 09:00 h. The data suggest that non weight trained individuals do not display a time of day effect for maximum squat or 5 m sprint performance, or the subsequent salivary hormonal response.
The role of sprint training in hamstring strain injury prevention for field sport athletes
- Authors: Freeman, Brock
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Hamstring strain injuries (HSI) are regularly reported as the most common injury in many field-based sports with a high-speed running (HSR) component. Typically, these injuries occur during sprinting efforts, predominantly in the Biceps Femoris Long Head (BFLH). Furthermore, the burden of HSI is amongst the highest in field sports, and the risk of recurrent injury is elevated, and inflated by age. It is of interest to managers, technical coaches, physical preparation staff and athletes to reduce the risk of sustaining a HSI. Therefore, extensive research in HSI has identified several non-modifiable and modifiable risk factors, such as eccentric hamstring strength, BFLH fascicle length, and HSR exposure. Currently, almost all interventions designed to reduce the risk of HSI have utilised resistance training or stretching interventions. This is despite the scientific literature indicating that; 1) sprinting is the most common mechanism associated with hamstring strain injury, and 2) sprinting places a far greater demand on the hamstrings than interventions that are resistance or flexibility based. Therefore, the primary aim of this thesis was to establish the role of sprint training in HSI prevention in field sport athletes. The aim of Study 1 was to understand the beliefs and practices of professional Australian Football (AF) physical performance coaches towards the training and assessment prescribed to mitigate the risk of HSI. A Delphi-validated mixed methods survey was implemented to assess the beliefs and practices of High-Performance Managers of professional AF teams. All the participants in this study reported that they believed sprinting (acceleration and maximum speed) was the most common activity associated with HSI. Similarly, all participants also indicated they performed sprint training for injury prevention purposes. However, a range of relative speeds were reported to quantify HSR, whilst a sprint was reported as 85%Vmax. Whilst respondents reported they believed that sprint training was important, one participant indicated that they felt the need to be conservative with the prescription of sprint training for fear of injury, and the consequences associated with this. Due to the identified discrepancies in speed thresholds used in practical setting (Study 1) and academic settings (Literature Review), Study 2 was designed to determine the absolute, and relative speeds associated with jogging, running, striding, near maximum sprinting, and sprinting. The secondary aim was to visually describe the gait patterns associated with HSR and sprinting. Fifteen participants completed two data collection periods, where they performed a series of run throughs at different gait patterns. These gait patterns were adapted from a review of time-motion research in field sports. The running gaits of jogging, running, striding, near-maximum sprinting, and sprinting correspond with the relative speeds of 56%Vmax, 66%Vmax, 78%Vmax, 87%Vmax, and 100%Vmax, respectively. Significant (p = 0.01) differences were observed for all variables between striding, near-maximum sprinting, and sprinting. This highlights that previously reported thresholds in Study 1 are likely not quantifying the true sprinting demands. Publicly available injury information indicates a spike in HSI during the 2018 Australian Football League (AFL) season, a trend that occurred in the relatively uninterrupted 2020 AFL season. As Study 2 indicated that thresholds used to quantify the demands of sprinting in training and competition, Study 3 primarily aimed to determine the amount of running completed in relative speed bands during the pre-season and then the first eight weeks of the season. The secondary aim was to determine how individual athletes vary from the group average across the pre-season and the first eight rounds of the season. This study completed a retrospective analysis of 55 professional Australian footballers during the pre-season and first eight rounds of the 2019 season. Significantly less (p < 0.05) weekly volume was reported during the first 8 weeks of the season in the speed thresholds of 71-80%Vmax, 81-90%Vmax, and 91-100%Vmax. However, athletes in this study only completed an average of 18m above 90%Vmax in the pre-season, a stimulus too low to achieve an injury prevention and conditioning effect. Individual analysis highlighted that whilst a small number of athletes achieved a consistent sprinting load, several athletes did not achieve more than 2m above 90%Vmax during both the pre and in-season periods. This lack of preparation may provide a rationale for the injury rates during the first eight rounds. To improve the preparation of athletes using a sprinting stimulus, Study 4 focussed on addressing modifiable risk factors for HSI. The primary aim of this study examined the effects of acceleration and maximum speed sprint training of eccentric hamstring strength, BFLH fascicle length, and sprint performance. Initially, a training study with 60 participants was planned, but due to the Victorian Government’s COVID-19 restrictions, this was modified to a case study design with 11 participants. A 6-week training intervention consisting of acceleration sprinting (<15m) or maximum speed sprinting with a gradual build up (flying 10-20m) was implemented. Participants that performed acceleration or maximum speed sprinting improved Biceps Femoris fascicle length by 23% and 20%, respectively. This was an increase of more than the Minimum Detectable Change (MDC95 = 0.96cm, 95% CI =0.93 – 0.99cm). The participants who completed normal training experienced no change in the BFLH fascicle length. Neither sprint training intervention produced a change in eccentric hamstring strength that was greater than the typical error in the test. Both sprinting interventions improved sprint performance outcomes, however both acceleration and maximum speed training produced a larger improvement in maximum speed (-11% and -9%, respectively) than in acceleration qualities (-2% and -3%, respectively). Both acceleration and maximum speed training incurred positive improvement in relative force production (F(0) (N/kg)) and relative power production (Pmax (W/kg)). This was similar for DRF and RFpeak and indicates that sprint training without resistance will improve Force-Velocity-Power Variables. This project has provided new information regarding the role of sprint training for hamstring strain injury prevention. Firstly, both 6 weeks of low volume acceleration and maximum speed sprinting improve BFLH fascicle length. Secondly, currently employed velocity thresholds in professional AF are likely too slow to quantify the HSR and sprinting demands. Thirdly, analysis using thresholds that are faster than previously reported revealed that the overall volume of sprinting (>90%Vmax) is too low to elicit an injury prevention or training stimulus. This information will inform the future practices of key stakeholders surrounding sprint training in field sport athletes. The identification of the positive benefits of maximum speed sprinting, and a faster, more accurate definition of sprinting has large potential to improve hamstring strain injury prevention and increase physical performance.
- Description: Doctor of Philosophy
- Authors: Freeman, Brock
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Hamstring strain injuries (HSI) are regularly reported as the most common injury in many field-based sports with a high-speed running (HSR) component. Typically, these injuries occur during sprinting efforts, predominantly in the Biceps Femoris Long Head (BFLH). Furthermore, the burden of HSI is amongst the highest in field sports, and the risk of recurrent injury is elevated, and inflated by age. It is of interest to managers, technical coaches, physical preparation staff and athletes to reduce the risk of sustaining a HSI. Therefore, extensive research in HSI has identified several non-modifiable and modifiable risk factors, such as eccentric hamstring strength, BFLH fascicle length, and HSR exposure. Currently, almost all interventions designed to reduce the risk of HSI have utilised resistance training or stretching interventions. This is despite the scientific literature indicating that; 1) sprinting is the most common mechanism associated with hamstring strain injury, and 2) sprinting places a far greater demand on the hamstrings than interventions that are resistance or flexibility based. Therefore, the primary aim of this thesis was to establish the role of sprint training in HSI prevention in field sport athletes. The aim of Study 1 was to understand the beliefs and practices of professional Australian Football (AF) physical performance coaches towards the training and assessment prescribed to mitigate the risk of HSI. A Delphi-validated mixed methods survey was implemented to assess the beliefs and practices of High-Performance Managers of professional AF teams. All the participants in this study reported that they believed sprinting (acceleration and maximum speed) was the most common activity associated with HSI. Similarly, all participants also indicated they performed sprint training for injury prevention purposes. However, a range of relative speeds were reported to quantify HSR, whilst a sprint was reported as 85%Vmax. Whilst respondents reported they believed that sprint training was important, one participant indicated that they felt the need to be conservative with the prescription of sprint training for fear of injury, and the consequences associated with this. Due to the identified discrepancies in speed thresholds used in practical setting (Study 1) and academic settings (Literature Review), Study 2 was designed to determine the absolute, and relative speeds associated with jogging, running, striding, near maximum sprinting, and sprinting. The secondary aim was to visually describe the gait patterns associated with HSR and sprinting. Fifteen participants completed two data collection periods, where they performed a series of run throughs at different gait patterns. These gait patterns were adapted from a review of time-motion research in field sports. The running gaits of jogging, running, striding, near-maximum sprinting, and sprinting correspond with the relative speeds of 56%Vmax, 66%Vmax, 78%Vmax, 87%Vmax, and 100%Vmax, respectively. Significant (p = 0.01) differences were observed for all variables between striding, near-maximum sprinting, and sprinting. This highlights that previously reported thresholds in Study 1 are likely not quantifying the true sprinting demands. Publicly available injury information indicates a spike in HSI during the 2018 Australian Football League (AFL) season, a trend that occurred in the relatively uninterrupted 2020 AFL season. As Study 2 indicated that thresholds used to quantify the demands of sprinting in training and competition, Study 3 primarily aimed to determine the amount of running completed in relative speed bands during the pre-season and then the first eight weeks of the season. The secondary aim was to determine how individual athletes vary from the group average across the pre-season and the first eight rounds of the season. This study completed a retrospective analysis of 55 professional Australian footballers during the pre-season and first eight rounds of the 2019 season. Significantly less (p < 0.05) weekly volume was reported during the first 8 weeks of the season in the speed thresholds of 71-80%Vmax, 81-90%Vmax, and 91-100%Vmax. However, athletes in this study only completed an average of 18m above 90%Vmax in the pre-season, a stimulus too low to achieve an injury prevention and conditioning effect. Individual analysis highlighted that whilst a small number of athletes achieved a consistent sprinting load, several athletes did not achieve more than 2m above 90%Vmax during both the pre and in-season periods. This lack of preparation may provide a rationale for the injury rates during the first eight rounds. To improve the preparation of athletes using a sprinting stimulus, Study 4 focussed on addressing modifiable risk factors for HSI. The primary aim of this study examined the effects of acceleration and maximum speed sprint training of eccentric hamstring strength, BFLH fascicle length, and sprint performance. Initially, a training study with 60 participants was planned, but due to the Victorian Government’s COVID-19 restrictions, this was modified to a case study design with 11 participants. A 6-week training intervention consisting of acceleration sprinting (<15m) or maximum speed sprinting with a gradual build up (flying 10-20m) was implemented. Participants that performed acceleration or maximum speed sprinting improved Biceps Femoris fascicle length by 23% and 20%, respectively. This was an increase of more than the Minimum Detectable Change (MDC95 = 0.96cm, 95% CI =0.93 – 0.99cm). The participants who completed normal training experienced no change in the BFLH fascicle length. Neither sprint training intervention produced a change in eccentric hamstring strength that was greater than the typical error in the test. Both sprinting interventions improved sprint performance outcomes, however both acceleration and maximum speed training produced a larger improvement in maximum speed (-11% and -9%, respectively) than in acceleration qualities (-2% and -3%, respectively). Both acceleration and maximum speed training incurred positive improvement in relative force production (F(0) (N/kg)) and relative power production (Pmax (W/kg)). This was similar for DRF and RFpeak and indicates that sprint training without resistance will improve Force-Velocity-Power Variables. This project has provided new information regarding the role of sprint training for hamstring strain injury prevention. Firstly, both 6 weeks of low volume acceleration and maximum speed sprinting improve BFLH fascicle length. Secondly, currently employed velocity thresholds in professional AF are likely too slow to quantify the HSR and sprinting demands. Thirdly, analysis using thresholds that are faster than previously reported revealed that the overall volume of sprinting (>90%Vmax) is too low to elicit an injury prevention or training stimulus. This information will inform the future practices of key stakeholders surrounding sprint training in field sport athletes. The identification of the positive benefits of maximum speed sprinting, and a faster, more accurate definition of sprinting has large potential to improve hamstring strain injury prevention and increase physical performance.
- Description: Doctor of Philosophy
Common high-speed running thresholds likely do not correspond to high-speed running in field sports
- Freeman, Brock, Talpey, Scott, James, Lachlan, Opar, David, Young, Warren
- Authors: Freeman, Brock , Talpey, Scott , James, Lachlan , Opar, David , Young, Warren
- Date: 2023
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 37, no. 7 (2023), p. 1411-1418
- Full Text: false
- Reviewed:
- Description: The purpose of this study was to clarify what percentage of maximum speed is associated with various running gaits. Fifteen amateur field sport athletes (age = 23 ± 3.6 years) participated in a series of 55-meter running trials. The speed of each trial was determined by instructions relating to 5 previously identified gait patterns (jog, run, stride, near maximum sprint, and sprint). Each trial was filmed in slow motion (240 fps), whereas running speed was obtained using Global Positioning Systems. Contact time, stride angle, and midstance free-leg knee angle were determined from video footage. Running gaits corresponded with the following running speeds, jogging = 4.51 m·s-1, 56%Vmax, running = 5.41 m·s-1, 66%Vmax,striding = 6.37 m·s-1, 78%Vmax, near maximum sprinting = 7.08 m·s-1, 87%Vmax, and sprinting = 8.15 m·s-1, 100%Vmax. Significant (p < 0.05) increases in stride angle were observed as running speed increased. Significant (p < 0.05) decreases were observed in contact time and midstance free-leg knee angle as running speed increased. These findings suggest currently used thresholds for high-speed running (HSR) and sprinting most likely correspond with jogging and striding, which likely underestimates the true HSR demands. Therefore, a higher relative speed could be used to describe HSR and sprinting more accurately in field sports. © 2023 NSCA National Strength and Conditioning Association. All rights reserved.
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