Predicting Weight Category-Specific Performance Zones for Olympic, World, and European Weightlifting Competitions.

ABSTRACT: Chavda, S, Comfort, P, Lake, JP, Bishop, C, and Turner, AN. Predicting weight category-specific performance zones for Olympic, World, and European weightlifting competitions. J Strength Cond Res 37(10): 2038-2045, 2023-Understanding the total likely required weight category to achieve a specific rank within a specific competition can aid in the long-term and short-term preparation and tactics for performance teams. The primary objective of this investigation was to develop a set of predictive models for new weight categories across 5 performance zones for 3 major weightlifting competitions. Performance total (Ptot) data for top 15 male athletes were obtained from the International Weightlifting Federation website from 1998 to 2020 across the Olympics, and World and European Championships. A second-order polynomial regression was conducted with 95% confidence, and predictive intervals were calculated. The average of the newly contested body mass was then used as the intercept. Predictions were compared against current performances of the new weight categories up to the 2020 Olympics. Results revealed that the models for all competition types varied in their predictive ability for each performance zone, across each new weight category. On average, predicted Ptot displayed a difference from actual Ptot of 3.65 ± 2.51% (12.46 ± 9.16 kg), 0.78 ± 3.29% (2.26 ± 10.08 kg), and -1.13 ± 3.46% (-4.32 ± 11.10 kg) for the Olympics, and World and European Championships, respectively. The results suggest that the predictive models may be a good indicator of future performances; however, the models may have greater efficacy in some weight categories and performance zones than others.

Measuring Interlimb Asymmetry for Strength and Power: A Brief Review of Assessment Methods, Data Analysis, Current Evidence, and Practical Recommendations.

ABSTRACT: Bishop, C, de Keijzer, KL, Turner, AN, and Beato, M. Measuring interlimb asymmetry for strength and power: A brief review of assessment methods, data analysis, current evidence, and practical recommendations. J Strength Cond Res 37(3): 745-750, 2023-The aim of this brief narrative review is to summarize the present evidence, provide recommendations for data analysis, and provide appropriate training methods to reduce strength and power asymmetries within athlete populations. Present evidence shows that a strong interest in the assessment of asymmetry exists. Despite the perceived associated relationship between asymmetry and injury and performance, a clear link is still missing. Practitioners need to be aware of this when they decide to assess asymmetries and later design training interventions. Several bilateral and unilateral tests could be used to assess asymmetries, such as isokinetic dynamometry, the isometric mid-thigh pull, squat, and Nordic hamstring exercise. Based on the current evidence, future investigations require further standardization of methodology and analysis to optimize interpretation (e.g., within session and between session), adoption, and implementation of interlimb asymmetry testing and appropriate interventions. In this review, 3 training interventions have been proposed to reduce existing lower limb asymmetries in sport populations: traditional resistance training, flywheel resistance training, and combined training interventions, with some evidence suggesting that such interventions can reduce lower limb asymmetries. Nonetheless, the number and quality of articles currently available are too limited to draw firm conclusions; therefore, further research is needed to verify whether training interventions can achieve these aims. To develop an understanding and application of interventions addressing interlimb asymmetries within the sport, greater methodological rigor should be applied toward study design, data analysis, and interpretation of future investigations and when appraising the current literature.

Contemporary Practices of Strength and Conditioning Coaches in High-Level Male Ice Hockey: A Survey-Based Investigation.

ABSTRACT: Galati, D, Turner, AN, Bishop, C, and Maloney, SJ. Contemporary practices of strength and conditioning coaches in high-level male ice hockey: a survey-based investigation. J Strength Cond Res 37(11): 2241-2250, 2023-The aim of this study was to provide an updated view of the common practices, ideologies, education level, and professional environment of strength and conditioning (S&C) coaches in elite male ice hockey. Nineteen S&C coaches from professional, semiprofessional, and top-tier collegiate hockey teams in North America completed an anonymous online survey. This was composed of 10 sections: (a) background information; (b) technology use, (c) testing and periodization, (d) strength and power, (e) flexibility/mobility, (f) speed, (g) plyometrics, (h) aerobic and anaerobic conditioning, (i) rehabilitation, and (j) challenges and areas of improvement. Fixed-response questions were analyzed through frequency analyses. Thematic analyses were used to identify common themes from open-response questions. Strength and conditioning coaches had an average of 8 (±6.5) years of experience when they accepted their current role. The majority held a master's degree and S&C certification. Muscular power, linear speed, and body composition were the most frequently tested qualities. Neuromuscular fatigue was the most important consideration during the season and least important consideration during the off-season. Training frequencies for all physical capacities were lower during the season compared with the off-season. All S&Cs had access to technology, with wearables, with force plates identified as the most used devices. This information may be used by S&C coaches to compare working practices with those used by their peers and inform them of the likely requirements and skill sets needed for job applications. Educational institutions may use this information to align teaching to current practice and to inform future research.

Alternate Leg Bounding Acutely Improves Change of Direction Performance in Women's Team Sports Players Irrespective of Ground Type.

ABSTRACT: Dann, E, Quinn, S, Russell, M, Kilduff, LP, Turner, AN, and Hills, SP. Alternate leg bounding acutely improves change-of-direction performance in women's team sports players irrespective of ground type. J Strength Cond Res 37(6): 1199-1203, 2023-This study aimed to assess whether body mass only alternate leg bounding performed post-warm-up on grass or a hard surface acutely improves preplanned change-of-direction performance in women's team sports players relative to a control condition and, if so, profile the time course of such changes. On 3 occasions, 14 amateur women's team sports players performed 20 m preplanned change-of-direction ("Pro-Agility") tests at 4, 8, and 12 minutes after interventions. Interventions were implemented immediately after a standardized warm-up and consisted of 3 sets of 10 repetitions of alternate leg bounding (5 ground contacts per limb) on a hard indoor surface (HARD) or natural grass (GRASS), or a control condition involving approximately 75 seconds of continuous walking with no bounding (CON). Performance was similar between conditions at 4-minutes postintervention. Performance at 8 minutes was greater in HARD (2.9%, p = 0.015) and GRASS (3.8%, p = 0.029) relative to CON, whereas GRASS also exceeded CON at 12 minute post-bounding (5.2%, p = 0.004). All effects were large. No differences existed between HARD and GRASS at any time. Irrespective of the ground surface, alternate leg bounding performed with body mass only can acutely improve indices of change-of-direction performance in women's team sports players when an appropriate post-stimulus recovery period is provided. Bounding on grass or a hard surface represents a feasible match-day practice that enhances subsequent change-of-direction performance and could therefore be used as part of practically applicable pre-match, half-time, and pitch-side (re)warm-up activities.

Intra- and Interday Reliability of Weightlifting Variables and Correlation to Performance During Cleans.

ABSTRACT: Sorensen, AM, Chavda, S, Comfort, P, Lake, J, and Turner, AN. Intra- and interday reliability of weightlifting variables and correlation to performance during cleans. J Strength Cond Res 36(11): 3008-3014, 2022-The purpose of this investigation was to examine intra- and interday reliability of kinetic and kinematic variables assessed during the clean, assess their relationship to clean performance, and determine their suitability in weightlifting performance analysis. Eight competitive weightlifters performed 3 sets of single repetition cleans with 90% of their 1-repetition maximum (1RM). Force-time data were collected via dual force plates with displacement-time data collected via 3-dimensional motion capture, on 3 separate occasions under the same testing conditions. Seventy kinetic and kinematic variables were analyzed for intra- and interday reliability using intraclass correlation coefficients (ICCs) and the coefficient of variation (CV). Pearson's correlation coefficients were calculated to determine relationships between barbell and body kinematics and ground reaction forces, and for correlations to be deemed as statistically significant, an alpha-level of p ≤ 0.005 was set. Eleven variables were found to have "good" to "excellent" intra- and interday ICC (0.779-0.994 and 0.974-0.996, respectively) and CV (0.64-6.89% and 1.14-6.37%, respectively), with strong correlations ( r = 0.880-0.988) to cleans performed at 90% 1RM. Average resultant force of the weighting 1 (W1) phase demonstrated the best intra- and interday reliability (ICC = 0.994 and 0.996, respectively) and very strong correlation ( r = 0.981) to clean performance. Average bar power from point of lift off to peak bar height exhibited the highest correlation ( r = 0.988) to clean performance. Additional reliable variables with strong correlations to clean performance were found, many of these occurred during or included the W1 phase, which suggests that coaches should pay particular attention to the performance of the W1 phase.

Convolutional Neural Networks for Challenges in Automated Nuclide Identification.

Improvements in Radio-Isotope IDentification (RIID) algorithms have seen a resurgence in interest with the increased accessibility of machine learning models. Convolutional Neural Network (CNN)-based models have been developed to identify arbitrary mixtures of unstable nuclides from gamma spectra. In service of this, methods for the simulation and pre-processing of training data were also developed. The implementation of 1D multi-class, multi-label CNNs demonstrated good generalisation to real spectra with poor statistics and significant gain shifts. It is also shown that even basic CNN architectures prove reliable for RIID under the challenging conditions of heavy shielding and close source geometries, and may be extended to generalised solutions for pragmatic RIID.

Comparing the magnitude and direction of asymmetry during the squat, countermovement and drop jump tests in elite youth female soccer players.

The aims of the present study were to provide an in-depth comparison of inter-limb asymmetry and determine how consistently asymmetry favours the same limb during different vertical jump tests. Eighteen elite female under-17 soccer players conducted unilateral squat jumps (SJ), countermovement jumps (CMJ) and drop jumps (DJ) on a portable force platform, with jump height, peak force, concentric impulse and peak power as common metrics across tests. For the magnitude of asymmetry, concentric impulse was significantly greater during the SJ test compared to CMJ (p = 0.019) and DJ (p = 0.003). No other significant differences in magnitude were present. For the direction of asymmetry, Kappa coefficients revealed fair to substantial levels of agreement between the SJ and CMJ (Kappa = 0.35 to 0.61) tests, but only slight to fair levels of agreement between the SJ and DJ (Kappa = -0.26 to 0.18) and CMJ and DJ (Kappa = -0.13 to 0.26) tests. These results highlight that the mean asymmetry value may be a poor indicator of true variability of between-limb differences in healthy athletes. The direction of asymmetry may provide a useful monitoring tool for practitioners in healthy athletes, when no obvious between-limb deficit exists.

Importance of Strength and Power on Key Performance Indicators in Elite Youth Soccer.

Wing, CE, Turner, AN, and Bishop, CJ. Importance of strength and power on key performance indicators in elite youth soccer. J Strength Cond Res 34(7): 2006-2014, 2020-The purpose of this investigation was to examine the importance of strength and power in relation to key performance indicators (KPIs) within competitive soccer match play. This was achieved through using an experimental approach in which 15 subjects were recruited from a professional soccer club's scholarship squad during the 2013/14 season. Following anthropometric measures, power and strength were assessed across a range of tests which included the squat jump (SJ), countermovement jump (CMJ), 20-m sprint, and arrowhead change of direction test. A predicted 1 repetition maximum (1RM) was also obtained for strength by performing a 3-RM test for both the back squat and bench press, and a total score of athleticism (TSA) was provided by summing Z-scores for all fitness tests together, providing 1 complete score for athleticism. Performance analysis data were collected during 16 matches for the following KPIs: passing, shooting, dribbling, tackling, and heading. Alongside this, data concerning player ball involvements (touches) were recorded. Results showed that there was a significant correlation (p ≤ 0.05) between CMJ (r = 0.80), SJ (r = 0.79), and TSA (r = 0.64) in relation to heading success. Similarly, a significant correlation (p ≤ 0.05) between predicted 1RM squat strength and tackle success (r = 0.61). These data support the notion that strength and power training are important to soccer performance, particularly when players are required to win duels of a physical nature. There were no other relationships found between the fitness data and the KPIs recorded during match play, which may indicate that other aspects of a player's development such as technical skill, cognitive function, and sensory awareness are more important for soccer-specific performance.

Acute and chronic effects of foam rolling vs eccentric exercise on ROM and force output of the plantar flexors.

Foam rolling and eccentric exercise interventions have been demonstrated to improve range of motion (ROM). However, these two modalities have not been directly compared. Twenty-three academy soccer players (age: 18 ± 1; height: 1.74 ± 0.08 m; body mass: 69.3 ± 7.5 kg) were randomly allocated to either a foam rolling (FR) or eccentric exercise intervention designed to improve dorsiflexion ROM. Participants performed the intervention daily for a duration of four weeks. Measurements of dorsiflexion ROM, isometric plantar flexion torque and drop jump reactive strength index were taken at baseline (pre-intervention) and at three subsequent time-points (30-min post, 24-hours post and 4-weeks post). A significant time x group interaction effect was observed for dorsiflexion (P = 0.036), but not for torque or reactive strength index. For dorsiflexion, there was a significant increase in both acute (30-min; P < 0.001) and chronic (4-week; P < 0.001) ROM for the eccentric group, whilst FR exhibited only an acute improvement (P < 0.001). Eccentric training would appear a more efficacious modality than foam rolling for improving dorsiflexion ROM in elite academy soccer players.

Lower Extremity Stiffness: Considerations for Testing, Performance Enhancement, and Injury Risk.

Brazier, J, Maloney, S, Bishop, C, Read, PJ, and Turner, AN. Lower extremity stiffness: considerations for testing, performance enhancement, and injury risk. J Strength Cond Res 33(4): 1156-1166, 2019-Force-deformation characteristics of the lower limb have been associated with athletic performance and may modulate the risk of injury. Despite these known associations, measurements of lower extremity stiffness are not commonly administered by strength and conditioning coaches. This review provides an overview of the available literature pertaining to the effects of lower extremity stiffness on physical performance and injury risk. Practical methods of monitoring and training stiffness are also discussed. The cumulative body of evidence indicates that increases in lower extremity stiffness are associated with heightened performance in athletic tasks such as hopping, jumping, throwing, endurance running, sprinting, and changing direction. Relationships with injury are less conclusive because both excessive and insufficient limb stiffness have been postulated to increase risk. Thus, the "optimal" level of stiffness seems to be dependent on the anthropometry and physical capabilities of the athlete, in addition to sport-specific activity demands. Training interventions can positively enhance lower extremity stiffness, including isometric, eccentric, and isotonic strength training and plyometrics. Complex training also seems to provide a potent stimulus and may be more effective than the use of singular training modes. For plyometric activities, it is recommended that coaches use a developmental sequence of exercises with increasing eccentric demand to provide an appropriate stimulus based on the training age and technical competency of the athlete.

Postactivation Potentiation and Change of Direction Speed in Elite Academy Rugby Players.

Marshall, J, Turner, AN, Jarvis, PT, Maloney, SJ, Cree, JA, and Bishop, CJ. Postactivation potentiation and change of direction speed in elite academy rugby players. J Strength Cond Res 33(6): 1551-1556, 2019-This study investigated the effect of preceding proagility sprints with maximal isometric squats to determine if postactivation potentiation (PAP) could be harnessed in change of direction speed. Sixteen elite under-17 rugby union players (age: 16 ± 0.41 years; body mass: 88.7 ± 12.1 kg; height: 1.83 ± 0.07 m) from an Aviva Premiership rugby club were tested. Subjects performed a change of direction specific warm-up, followed by 2 baseline proagility tests. After 10-minute recovery, 3 × 3-second maximal isometric squats with a 2-minute recovery between sets were completed as a conditioning activity (CA) on a force plate where peak force and mean rate of force development over 300 milliseconds were measured. The proagility test was repeated at set time intervals of 1, 3, 5, and 7 minutes after the CA. Overall proagility times were significantly slower (p < 0.05) at 1 minute post-CA compared with the baseline (3.3%), with no significant differences occurring at 3, 5, or 7 minutes post-CA. Therefore, it appears that performing multiple sets of maximal isometric squats do not enhance proagility performance.

Characteristics and experiences of interns in strength and conditioning.

Student coaches undertake internships to develop practical skills and gain experience to improve employability prospects. The characteristics of the coaches who undertake these internships, their experiences and the nature of the work being performed are currently unknown. The purpose of this study was to report the characteristics of strength and conditioning (S&C) coaches who have undertaken internships and their experiences during their respective placements. A total of 113 men and 6 women completed an online survey. Placements generally lasted 6-12 months (66%), were unpaid (93%) and took place at professional teams (63%). All respondents had a standard of experience prior to commencement (82%); a higher-education degree (bachelor's degree 56%; master's degree 18%) and others were qualified S&C coaches (16%). Activities consisted largely of coaching (47%), data collection (22%) and equipment set-up (25%) but lacked provision of appropriate training. Mentors were allocated to interns; however, often developmental objectives were not discussed, meetings were rarely documented, and in some cases, no meetings took place. This study suggests that internships offer worthwhile experiences and assistance in skill development to progress in S&C. However, clearer guidelines are required to define the responsibilities of employers and interns, to maximise these experiential learning opportunities and avoid the exploitation of willing students.

Using the Split Squat to Potentiate Bilateral and Unilateral Jump Performance.

Bishop, CJ, Tarrant, J, Jarvis, PT, and Turner, AN. Using the split squat to potentiate bilateral and unilateral jump performance. J Strength Cond Res 31(8): 2216-2222, 2017-The purpose of this study was to examine if a split squat conditioning exercise with no or light loads could potentiate unilateral and bilateral jump performance. Twelve semiprofessional rugby players (age: 22.3 ± 1.4 years; height: 1.84 ± 0.05 m, mass: 92.4 ± 9.6 kg) from the English National League 1 performed a series of unilateral and bilateral countermovement jumps (CMJ) and broad jumps (BJ) over the course of 2 testing days. Both testing days involved performing baseline jumps before completing 2 sets of 10 repetitions of a split squat, this completed with either bodyweight (testing session 1) or a 30 kg weighted vest (testing session 2). A 5-minute recovery period was permitted both after the warm-up and the completion of the split squat exercise. Significantly larger bilateral jump scores were reported after completion of the bodyweight split squat: CMJ (p = 0.001, ES = 0.44, [mean difference 2.517]), BJ (p = 0.001, ES = 0.37, [mean difference 3.817]), and the weighted vest split squat; CMJ (p = 0.001, ES = 0.8, [mean difference 4.383]), BJ (p = 0.001, ES = 0.68, [mean difference 6.817]). The findings of this study demonstrate that no or light loads of a split squat conditioning exercise are able to potentiate bilateral jump performance in semiprofessional rugby players without the need for expensive weight room equipment. As such, this may provide coaches with a viable option of enhancing bilateral jump performance as part of a warm-up or on-field conditioning practice.

Do Fencers Require a Weapon-Specific Approach to Strength and Conditioning Training?

There are 3 types of weapons used in Olympic fencing: the épée, foil, and sabre. The aim of this study was to determine if fencers exhibited different physical characteristics across weapons. Seventy-nine male (n = 46) and female (n = 33) national standard fencers took part in this study. Fencers from each weapon (male and female), i.e., épée (n = 19 and 10), foil (n = 22 and 14), and sabre (n = 13 and 10), were (mean ± SD) 15.9 ± 0.7 years of age, 178.5 ± 7.9 cm tall, 67.4 ± 12.2 kg in mass and had 6.3 ± 2.3 years fencing experience; all were in regular training (∼4 times per week). Results revealed that across all performance tests (lower-body power, reactive strength index, change of direction speed, and repeat lunge ability), there was no significant main effect for weapon in male fencers (p = 0.63) or female fencers (p = 0.232), but a significant main affect for gender (p < 0.001). Pairwise comparisons revealed that male fencers scored better during the countermovement jump, change of direction speed, and repeat lunge ability test (p < 0.001). The former findings may be because of similarities in bout intensity and time, movement types (lunging and changing direction), and the need to execute competition actions as explosively as possible. Based on the findings of the present study, it could be indicated that épée, foil, and sabre fencers do not require a weapon-specific approach to strength and conditioning training. Each fencer should target the area they are weakest at, rather than an area that they feel best represents the unique demands of their weapon.

Competition Intensity and Fatigue in Elite Fencing.

Turner, AN, Kilduff, LP, Marshall, GJG, Phillips, J, Noto, A, Buttigieg, C, Gondek, M, Hills, FA, and Dimitriou, L. Competition intensity and fatigue in elite fencing. J Strength Cond Res 31(11): 3128-3136, 2017-As yet, no studies have characterized fencing competitions. Therefore, in elite male foilists and across 2 competitions, we investigated their countermovement jump height, testosterone (T), cortisol (C), alpha-amylase (AA), immunoglobulin A (IgA), heart rate (HR), blood lactate (BL), and rating of perceived exertion (RPE). Average (±SD) scores for RPE, BL, and HR (average, max, and percentage of time ≥80% HRmax) were highest in the knockout bouts compared with poules (8.5 ± 1.3 vs. 5.7 ± 1.3, 3.6 ± 1.0 vs. 3.1 ± 1.4 mmol·L, 171 ± 5 vs. 168 ± 8 b·min, 195 ± 7 vs. 192 ± 7 b·min, 74 vs. 68%); however, only significant (p ≤ 0.05) for RPE. Countermovement jump height, albeit nonsignificantly (p > 0.05), increased throughout competition and dropped thereafter. Although responses of C, AA, and IgA showed a tendency to increase during competition and drop thereafter (T and T:C doing the opposite), no significant differences were noted for any analyte. Results suggest that fencing is a high-intensity anaerobic sport, relying on alactic energy sources. However, some bouts evoke BL values of ≥4 mmol·L and thus derive energy from anaerobic glycolysis. High HRs appear possible on account of ample within- and between-bout rest. The small competition load associated with fencing competitions may explain the nonsignificant findings noticed.

Determinants of Club Head Speed in PGA Professional Golfers.

Turner, AN. Determinants of club head speed in PGA professional golfers. J Strength Cond Res 30(8): 2266-2270, 2016-Club head speed (CHS) has been significantly correlated with golf performance, but only in amateurs. The purpose of this study therefore, was to investigate the relationship between field-based measures of strength and power with CHS in Professional Golfers Association (PGA) professional golfers, and further determine differences between age groups. A correlation design was used to test relationships between squat jump (SJ), seated medicine ball throw (SMBT), rotational medicine ball throw (RMBT), and CHS. Twenty participants volunteered to take part in the study (age, 31.95 ± 8.7 years; height, 182.75 ± 6.88 cm; mass, 90.47 ± 15.6 kg). Intraclass correlation coefficients reported high reliability for performance variables (r = 0.85-0.95). Significant correlations (p < 0.01) were found between CHS and SJ (r = 0.817) and SMBT (r = 0.706), but not RMBT (r = 0.572). A stepwise linear regression analysis identified that SJ and SMBT explained 74% of the variance in CHS. When dividing the sample based on age, professionals <30 years (n = 10; 25.6 ± 2.9 years) displayed significantly (p ≤ 0.05) higher CHS and SJ height compared with professionals >30 (n = 10; 39.7 ± 5.5 years). Correlations to CHS for <30 were significant for SJ (r = 0.801) and SMBT (r = 0.643), but nonsignificant for RMBT. Those >30 had significant correlations to CHS not only in SMBT (r = 0.881) and SJ (r = 0.729), but also in RMBT (r = 0.642). The results of this study suggest that SJ and SMBT have the largest contribution to CHS in PGA professional golfers. When comparing age groups, it appears that younger golfers (<30 years) utilize more leg strength whereas older golfers (>30 years) utilize more upper body strength. Results suggest that strength-based leg exercises and power-based chest exercises may improve CHS in professional golfers.

Physical Characteristics Underpinning Repetitive Lunging in Fencing.

Turner, AN, Marshall, G, Phillips, J, Noto, A, Buttigieg, C, Chavda, S, Downing, W, Atlay, N, Dimitriou, L, and Kilduff, L. Physical characteristics underpinning repetitive lunging in fencing. J Strength Cond Res 30(11): 3134-3139, 2016-Given the repetitive demand to execute lunging and changes in direction within fencing, the ability to sustain these at maximal capacity is fundamental to performance. The aim of this study was threefold. First, to provide normative values for this variable referred to as repeat lunge ability (RLA) and second to identify the physical characteristics that underpin it. Third, was to establish if a cause and effect relationship existed by training the associated characteristics. Assessment of lower-body power, reactive strength, speed, change of direction speed (CODS), and a sport-specific RLA were conducted on senior and junior elite male fencers (n = 36). Fencers were on average (±SD) 18.9 ± 3.2 years of age, 174.35 ± 10.42 cm tall, 70.67 ± 7.35 kg in mass, and 8.5 ± 4.2 years fencing experience. The RLA test had average work times of 16.03 ± 1.40 seconds and demonstrated "large" to "very large" associations with all tested variables, but in particular CODS (r = 0.70) and standing broad jump (SBJ; r = -0.68). Through linear regression analysis, these also provided a 2-predictor model accounting for 61% of the common variance associated with RLA. A cause and effect relationship with SBJ and CODS was confirmed by the training group, where RLA performance in these fencers improved from 15.80 ± 1.07 to 14.90 ± 0.86 seconds, with the magnitude of change reported as "moderate" (effect size (ES) = 0.93). Concurrent improvements were also noted in both SBJ (216.86 ± 17.15 vs. 221.71 ± 17.59 cm) and CODS (4.44 ± 0.29 vs. 4.31 ± 0.09 seconds) and while differences were only significant in SBJ, magnitudes of change were classed as "small" (ES = 0.28) and "moderate" (ES = 0.61), respectively. In conclusion, to improve RLA strength and conditioning coaches should focus on improving lower-body power and reactive strength, noting that jump training and plyometrics designed to enhance horizontal propulsion may be most effective, and translate to improvement in CODS also.

Effect of postactivation potentiation on fifty-meter freestyle in national swimmers.

The purpose of this study was to examine the effect of PAP on 50-m freestyle in national-level swimmers. Four warm-ups were compared: a traditional race-specific warm-up (RSWU), upper-body PAP (UBPAP), lower-body PAP (LBPAP), and combined PAP warm-up (CPAP). Eighteen (10 men, 8 women) national-level swimmers participated in this study, which included 7 separate testing sessions. Participants' 3 repetition maximum (3RM) of the pull-up (PU) was established in session 1. In session 2, rest periods for muscle enhancement of the upper body were determined using a medicine ball throw test 4, 8, and 12 minutes after UBPAP stimulus (1 × 3RM of the PU). In session 3, swimmers performed a countermovement jump 4, 8, and 12 minutes after LBPAP stimulus (1 × 5 jumps to a box while carrying 10% of the participants' body weight). The 50-m freestyle tests were performed on sessions 4-7, preceded by each warm-up protocol and corresponding rest periods. A repeated-measures analysis of variance (p ≤ 0.05) and Bonferroni post hoc test revealed that RSWU elicited faster swimming times than UBPAP (29.00 ± 2.05 vs. 29.36 ± 1.88 seconds, p = 0.046). Additionally, when data were split into gender, in the male group, the UBPAP elicited significantly slower times than RSWU (27.51 ± 1.06 vs. 28.01 ± 1.17 seconds, p = 0.047) and CPAP (27.49 ± 1.12 vs. 28.01 ± 1.17 seconds, p = 0.02). These findings suggest individualized PAP warm-up may be a valuable tool to enhance performance in sprint events, particularly in male swimmers. However, the PU may not be an appropriate PAP stimulus on its own.

Effects of Concurrent Activation Potentiation on Countermovement Jump Performance.

The purpose of this study was to assess the effects of concurrent activation potentiation (CAP) on countermovement jump (CMJ) performance. Twenty-four resistance-trained males (mean ± SD; age: 25 ± 4 years, body mass: 78.7 ± 10.3 kg) performed a CMJ on a force plate under 4 different conditions: (a) a control condition where the CMJ was performed with hands on hips and lips pursed, thus preventing jaw or fist contraction from occurring, (b) a jaw condition where the CMJ was performed with maximal contraction of the jaw, (c) a fist condition where the CMJ was performed with maximal contraction of the fists, and (d) a combined condition where the CMJ was performed with maximal contraction of both jaw and fists. Jump height (JH), peak force (PF), rate of force development (RFD), and time to peak force (TTPF) were calculated from the vertical force trace. There was no significant difference in PF (p = 0.88), TTPF (p = 0.96), JH (p = 0.45), or RFD (p = 0.06) between the 4 conditions. Effect size (ES) comparisons suggest a potential for CMJ with fist and jaw contraction (BOTH condition) to augment both PF (2.4%; ES: 0.62) and RFD (9.9%; ES: 0.94) over a normal CMJ (NORM condition). It is concluded that CAP by singular and combined contractions has no significant impact on CMJ performance; however, substantial interindividual variation in response to CAP was observed, and such techniques may therefore warrant consideration on an individual basis.

Acute effects of a loaded warm-up protocol on change of direction speed in professional badminton players.

It has previously been shown that a loaded warm-up may improve power performances. We examined the acute effects of loaded dynamic warm-up on change of direction speed (CODS), which had not been previously investigated. Eight elite badminton players participated in three sessions during which they performed vertical countermovement jump and CODS tests before and after undertaking the dynamic warm-up. The three warm-up conditions involved wearing a weighted vest (a) equivalent to 5% body mass, (b) equivalent to 10% body mass, and (c) a control where a weighted vest was not worn. Vertical jump and CODS performances were then tested at 15 seconds and 2, 4, and 6 minutes post warm-up. Vertical jump and CODS significantly improved following all warm-up conditions (P < .05). Post warm-up vertical jump performance was not different between conditions (P = .430). Post warm-up CODS was significantly faster following the 5% (P = .02) and 10% (P < .001) loaded conditions compared with the control condition. In addition, peak CODS test performances, independent of recovery time, were faster than the control condition following the 10% loaded condition (P = .012). In conclusion, the current study demonstrates that a loaded warm-up augmented CODS, but not vertical jump performance, in elite badminton players.