Global Industry Perspectives on Postgraduate Strength and Conditioning Degrees: An Exploratory Factor Analysis.

PURPOSE: This investigation sought to determine industry perceptions of postgraduate strength and conditioning (S&C) degrees to understand whether graduates are equipped for the demands of sport performance service roles. METHODS: Survey data were collected from 111 participants employed as performance staff or in a role that recruits and supervises performance staff. The survey consisted of 3 main sections: (1) perceptions of career-development opportunities in S&C, (2) perception of S&C postgraduate programs, and (3) perceptions of employability in S&C. Exploratory factor analysis was conducted to identify the key factors considered to be of greatest relevance to career progression in S&C. RESULTS: A 2-factor solution was achieved for each of the 3 sections, resulting in 6 total factors. These factors are Academic and Professional Development, Mentorship and Sport Diversity, Student Preparation, Require Greater Emphasis, Testing and Training, and Personal and Professional Growth. CONCLUSIONS: Postgraduate S&C programs require a broad range of placement/internship opportunities to (1) provide diverse experiences, (2) allow students to build contacts and develop professional networks, (3) gain exposure to working in high-performance environments and multidisciplinary teams, and (4) access high-quality mentors. Alongside the ability to deliver training and testing, graduates should be equipped with strong organizational and relationship-building skills. Improved graduate capabilities can raise the standards of the profession and result in enhanced service provision to athletes.

Preseason and In-Season High-Speed Running Demands of 2 Professional Australian Rules Football Teams.

BACKGROUND: Australian Rules Football athletes complete long preseasons, yet injuries occur frequently at early stages of the competitive season. Little is known about the high-speed running (HSR) prescription during a preseason or whether players are adequately prepared for competition. This study described absolute and relative preseason and in-season HSR demands of 2 professional Australian football teams. HYPOTHESIS: HSR and sprinting volumes are significantly lower in elite Australian Rules football athletes during in-season compared with preseason. STUDY DESIGN: Cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: During the 2019 season, HSR volume was collected for 2 professional Australian football teams (n = 55). Individual maximum speeds (Vmax) were captured to calculate relative running speed thresholds, as reported in 5% increments from 70%Vmax to 100%Vmax. RESULTS: Weekly volume of running above 70%Vmax (P = 0.01; r = 0.56) and 80%Vmax (P = 0.01; r = 0.58) was significantly greater in the preseason than the in-season. The weekly volume completed above 90%Vmax was not significantly greater in the preseason than the in-season (P = 0.10; r = 0.22). Individual variation in the distance completed at specific percentages of Vmax expressed as a coefficient of variation was reported as 51% at 71% to 80%Vmax, 39% at 81% to 90%Vmax, and 41% at 91% to 100%Vmax. CONCLUSION: The volume of HSR completed by athletes is far greater in the initial 4 weeks of the preseason than in any other point in preseason or competitive phases. At the individual level, there is substantial variation in the distance covered. This supports the concept of a heavily individualized approach to high-speed prescription and monitoring. CLINICAL RELEVANCE: Practitioners should carefully consider individual variation regarding sprinting volume during both preseason and in-season when prescribing and monitoring training to improve on-field performance and reduce the risk of injury.

Pairwise Comparison of Heavy Dynamic Strength and Fast Dynamic Strength Interventions on Sprint Performance: A Systematic Review and Meta-Analysis.

ABSTRACT: Pairwise comparison of heavy dynamic strength and fast dynamic strength interventions on sprint performance: a systematic review and meta-analysis. J Strength Cond Res 38(9): 1675-1686, 2024-Previous studies have shown that both heavy dynamic strength (HDS) and fast dynamic strength (FDS) training can be used to improve sprint performance; however, a review and meta-analysis investigating pairwise studies that compare these two training interventions have not been performed. The aims of the study were to systematically review and analyze HDS and FDS training methodologies and evaluate their effect size difference, in pairwise comparison studies to determine and compare their effects on sprint performance. Databases were systematically searched using Boolean phrasing to identify eligible articles, and meta-analyses were performed on the extracted data. Seven studies met the inclusion criteria, which resulted in data from 138 subjects across 24 separate sprint assessments. Overall, there was a small effect in favor of FDS (standardized mean difference = 0.27, 95% confidence intervals [-0.07; 0.60], 95% prediction intervals [-1.01; 1.55]), but this was deemed not significant because of the wide-ranging prediction intervals. There is no distinguishable difference between HDS and FDS training on sprint performance. The wide-ranging prediction intervals suggest the variability is too great to determine whether one training type is more effective than the other. Practitioners should consider the individual needs of their athletes when deciding which training type to use for long-term sprint development.

Classification of Force-Time Metrics Into Lower-Body Strength Domains.

ABSTRACT: Geneau, MC, Carey, DL, Gastin, PB, Robertson, S, and James, LP. Classification of force-time metrics into lower-body strength domains. J Strength Cond Res 38(9): 1561-1567, 2024-The purpose of this study was to classify force-time metrics into distinct lower-body strength domains using a systematic data reduction analysis. A cross-sectional design was used, whereby competitive field sport athletes ( F = 39, M = 96) completed a series of drop jumps, squat jumps, countermovement jumps (CMJs), loaded CMJs, and 2 isometric tasks on portable force platforms, resulting in a total of 285 force-time performance metrics. The metrics were split into 4 test "families" and each was entered into a sparse principal component analysis (sPCA) model. A single metric from each component of each family-specific sPCA were selected based on the loading, reliability, and simplicity of the metric and entered into a second sPCA that included metrics across all tests. The final sPCA revealed 7 principal components each containing 2 metrics and explained a total of 53% variance of the dataset. The final principal components were interpreted as 7 lower-body strength domains: (a) dynamic force, (b) dynamic timing, (c) early isometric, (d) maximal isometric, (e) countermovement velocity, (f) reactive output, and (g) reactive timing. The findings demonstrate that a total of 7 metrics from a drop jump, CMJ, and isometric test can be used to represent ∼50% of variance in lower-body strength performance of field sport athletes. These results can help guide and simplify the lower-body strength diagnosis process in field sport athletes.

A framework for test measurement selection in athlete physical preparation.

Preparing athletes for competition requires the diagnosis and monitoring of relevant physical qualities (e.g., strength, power, speed, endurance characteristics). Decisions regarding test selection that attempt to measure these physical attributes are fundamental to the training process yet are complicated by the myriad of tests and measurements available. This article presents an evidenced based process to inform test measurement selection for the physical preparation of athletes. We describe a method for incorporating multiple layers of validity to link test measurement to competition outcome. This is followed by a framework by which to evaluate the suitability of test measurements based on contemporary validity theory that considers technical, decision-making, and organisational factors. Example applications of the framework are described to demonstrate its utility in different settings. The systems presented here will assist in distilling the range of measurements available into those most likely to have the greatest impact on competition performance.

Evaluating the effect of sports compression tights on balance, sprinting, jumping and change of direction tasks.

Compression garments are commonly used during athletic tasks. However, the effect of compression garments on balance, sprinting, jumping and change of direction performance requires further investigation. In the current study, 24 recreationally active participants (12 males, 12 females, age 27 ± 3 years) completed single-leg balance tasks, countermovement jumps, drop jumps, 10 m straight line sprints and change of direction tasks wearing either compression tights (COMP) or regular exercise tights (CON). There was a significant main effect of the condition for 10 m sprint time (p = 0.03, d = -0.18) and change of direction time (p = 0.03, d = -0.20) in favour of COMP. In addition, there was a significant, small difference (p = 0.05, d = -0.30) in ellipse area and a small (p = 0.16, d = 0.21) difference in balance time in favour of COMP during a single-leg balance task. There were no significant differences between trials for any of the other balance or jump tests (p > 0.05). The application of compression tights during exercise may offer small benefits to the performance of balance and change of direction tasks, though these benefits are likely within the typical error of measurement for the tests used.

Under the Gun: Percussive Massage Therapy and Physical and Perceptual Recovery in Active Adults.

CONTEXT: Handheld percussive massage devices (ie, massage guns) are a relatively new and under-researched recovery tool. These tools are intended to increase range of motion and reduce muscle soreness by delivering targeted vibration to soft tissues. Empirical knowledge about the potential influence of these devices on perceptual recovery and the recovery of performance characteristics after exercise is scarce. OBJECTIVE: To investigate the effect of a 5-minute massage gun application, using a commercially available device, on physical and perceptual recovery after a strenuous bout of lower body exercise. DESIGN: Controlled laboratory study. SETTING: Physiology laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 65 active young adults (age = 21.3 ± 1.4 years; age range = 18-30 years; 34 women: height = 165.8 ± 6.1 cm, mass = 66.0 ± 7.4 kg; 31 men: height = 181.1 ± 6.0 cm, mass = 81.5 ± 11.8 kg). INTERVENTION(S): Participants applied a massage gun on the calf muscles of 1 leg after strenuous exercise (massage gun recovery group) for 5 minutes and used no recovery intervention on the other leg (control group). MAIN OUTCOME MEASURE(S): Ankle range of motion, calf circumference, isometric strength, calf endurance, and perceived muscle soreness measures were collected at baseline and at various points after lower body exercise. RESULTS: No significant group × time interactions were recorded for any of the performance or perceptual measures (P values > .05). Effect sizes were mostly unclear, except for a small increase in perceived muscle soreness in the massage gun recovery group compared with the control group immediately (d = -0.35) and 4 hours (d = -0.48) postrecovery. CONCLUSIONS: Massage guns appeared to have little effect on physical measures when applied for 5 minutes immediately after strenuous calf exercise. Given the small increase in muscle soreness up to 4 hours after their use, caution is recommended when using massage guns immediately after strenuous lower body exercise.

The Relationship Between Isometric and Dynamic Strength Following Resistance Training: A Systematic Review, Meta-Analysis, and Level of Agreement.

BACKGROUND: Maximal lower-body strength can be assessed both dynamically and isometrically; however, the relationship between the changes in these 2 forms of strength following resistance training is not well understood. PURPOSE: To systematically review and analyze the effects of resistance training on changes in maximal dynamic (1-repetition-maximum back squat, deadlift, and power clean) and position-matched isometric strength (isometric midthigh pull and the isometric squat). In addition, individual-level data were used to quantify the agreement and relationship between changes in dynamic and isometric strength. METHODS: Databases were systematically searched to identify eligible articles, and meta-analysis procedures were performed on the extracted data. The raw results from 4 studies were acquired, enabling bias and absolute reliability measures to be calculated using Bland-Altman test of agreement. RESULTS: Eleven studies met the inclusion criteria, which resulted in 29 isometric-dynamic change comparisons. The overall pooled effect was 0.13 in favor of dynamic testing; however, the prediction interval ranged from g = -0.49 to 0.75. There was no evidence of bias (P = .825) between isometric and dynamic tests; however, the reliability coefficient was estimated to be 16%, and the coefficient of variation (%) was 109.27. CONCLUSIONS: As a range of future effects can be expected when comparing isometric to dynamic strength changes following resistance training, and limited proportionality exists between changes in these 2 strength qualities, there is strong evidence that isometric and dynamic strength represent separate neuromuscular domains. These findings can be used to inform strength-assessment models in athlete populations.

The Effects of Low-Load Squat Jump and Maximal Isometric Priming Exercise on Muscular Performance and Perceptual State.

ABSTRACT: Harrison, PW, James, LP, Jenkins, DG, McGuigan, MR, Holmberg, PM, and Kelly, VG. The effects of low-load squat jump and maximal isometric priming exercise on muscular performance and perceptual state. J Strength Cond Res 38(1): 1-9, 2024-The aim of this study was to examine responses at 3 and 27 hours after low-load jump squat (LL) and maximal isometric half-squat (ISO) priming stimuli. Fifteen resistance-trained males performed LL (4 × 3 at 20% 1 repetition maximum [1RM]), ISO (4 × 3 seconds), and control (CON) activities (standardized warm-up) in a randomized and counterbalanced order. Countermovement jump (CMJ) and isometric midthigh pull tests were conducted to assess performance changes after priming and CON activities. No clear changes in CMJ measures were found after priming activities compared with CON. However, small effect size improvements were found after priming stimuli completed on the same day. A 2.9% decrease in concentric phase duration (CI = 0.3-5.9, p = 0.333, Cliff's delta = -0.156) and a 9.1% increase in RSImod (CI = 0.2-12.3, p = 0.151, Cliff's delta = -0.218) occurred at 3 hours after LL compared with CON. Braking phase duration (CI = 0.8-10.6, p = 0.333, Cliff's delta = -0.213) was 2.9% shorter at 3 hours after ISO compared with CON. No clear changes in isometric peak force occurred after priming activities compared with CON. Additionally, questionnaires were completed to assess perceptual state and perceived effectiveness of the priming stimulus to influence performance. An increase in the "effect of activity" was perceived at 3 hours after LL and ISO (p = 0.013-0.044, Cliff's delta = 0.578-0.6) and at 27 hours after ISO (p = 0.99, Cliff's delta = 0.173) compared with CON. An increase in "muscular heaviness" was also reported at 3 hours after ISO compared with CON (p = 0.199, Cliff's delta = 0.320). The collective findings suggest limited benefits over the day after LL and ISO priming stimuli. However, as there was substantial variation in individual responses, the relative nature of priming responses should be considered when prescribing similar strategies in practical environments.

Effects of Repeated Jump Testing and Diurnal Changes on Subsequent Countermovement Jump and Squat Jump Output and Force-Time Characteristics.

ABSTRACT: Harrison, PW, James, LP, Jenkins, DG, Holmberg, PM, and Kelly, VG. Effects of repeated jump testing and diurnal changes on subsequent countermovement jump and squat jump output and force-time characteristics. J Strength Cond Res 38(1): 174-179, 2024-The aim of this brief study was to investigate the effects of repeated jump testing on performance over 2 consecutive days while considering the possibility of diurnal changes. Fourteen male subjects and 14 recreationally active female subjects completed countermovement jump (CMJ) and squat jump (SJ) testing on 5 occasions (baseline [0,800], 5 minutes [0,820], 8 hours [1,600], 24 hours [0,800], and 32 hours [1,600]) over 32 hours. An additional rested baseline test was conducted on a separate day in the afternoon (1,600) to compare jump performance between morning and afternoon baseline values. Excluding small decreases in CMJ height at 24 hours (p = 0.292, Cliff's delta = -0.225) in male subjects and similar decreases in CMJ height at 5 minutes (p = 0.034, Cliff's delta = -0.245) in addition to SJ height:contraction time at 32 hours (p = 0.126, Cliff's delta = 0.153) in female subjects, findings generally showed no changes in jump performance over multiple assessments. Squat jump metrics may have showed small improvements between morning and afternoon baseline values in male subjects (SJ height:contraction time [p = 0.030, Cliff's delta = 0.225]) and female subjects (SJ height [p = 0.013, Cliff's delta = 0.173] and SJ height:contraction time [p = 0.091, Cliff's delta = 0.163)]. As jump performance was largely unaffected by repeated jump testing, the present findings support the use of monitoring practices and research designs that require multiple jump assessments within acute periods (∼32 hours).

The Effects of Repeated-Sprint Training on Physical Fitness and Physiological Adaptation in Athletes: A Systematic Review and Meta-Analysis.

BACKGROUND: Repeated-sprint training (RST) is a common training method for enhancing physical fitness in athletes. To advance RST prescription, it is important to understand the effects of programming variables on physical fitness and physiological adaptation. OBJECTIVES: This study (1) quantifies the pooled effects of running RST on changes in 10 and 20 m sprint time, maximal oxygen consumption (VO2max), Yo-Yo Intermittent Recovery Test Level 1 (YYIR1) distance, repeated-sprint ability (RSA), countermovement jump (CMJ) height and change of direction (COD) ability in athletes, and (2) examines the moderating effects of program duration, training frequency, weekly volume, sprint modality, repetition distance, number of repetitions per set and number of sets per session on changes in these outcome measures. METHODS: Pubmed, SPORTDiscus and Scopus databases were searched for original research articles up to 04 July 2023, investigating RST in healthy, able-bodied athletes, between 14 and 35 years of age, and a performance calibre of trained or above. RST interventions were limited to repeated, maximal running (land-based) sprints of ≤ 10 s duration, with ≤ 60 s recovery, performed for 2-12 weeks. A Downs and Black checklist was used to assess the methodological quality of the included studies. Eligible data were analysed using multi-level mixed-effects meta-analysis, with standardised mean changes determined for all outcomes. Standardised effects [Hedges G (G)] were evaluated based on coverage of their confidence (compatibility) intervals (CI) using a strength and conditioning specific reference value of G = 0.25 to declare an improvement (i.e. G > 0.25) or impairment (i.e. G < - 0.25) in outcome measures. Applying the same analysis, the effects of programming variables were then evaluated against a reference RST program, consisting of three sets of 6 × 30 m straight-line sprints performed twice per week for 6 weeks (1200 m weekly volume). RESULTS: 40 publications were included in our investigation, with data from 48 RST groups (541 athletes) and 19 active control groups (213 athletes). Across all studies, the effects of RST were compatible with improvements in VO2max (G 0.56, 90% CI 0.32-0.80), YYIR1 distance (G 0.61, 90% CI 0.43-0.79), RSA decrement (G - 0.61, 90% CI - 0.85 to - 0.37), linear sprint times (10 m: G - 0.35, 90% CI - 0.48 to - 0.22; 20 m: G - 0.48, 90% CI - 0.69 to - 0.27), RSA average time (G - 0.34, 90% CI - 0.49 to - 0.18), CMJ height (G 0.26, 90% CI 0.13-0.39) and COD ability (G - 0.32, 90% CI - 0.52 to - 0.12). Compared with the reference RST program, the effects of manipulating training frequency (+ 1 session per week), program duration (+ 1 extra training week), RST volume (+ 200 m per week), number of reps (+ 2 per set), number of sets per session (+ 1 set) or rep distance (+ 10 m per rep) were either non-substantial or comparable with an impairment in at least one outcome measure per programming variable. CONCLUSIONS: Running-based RST improves speed, intermittent running performance, VO2max, RSA, COD ability and CMJ height in trained athletes. Performing three sets of 6 × 30 m sprints, twice per week for 6 weeks is effective for enhancing physical fitness and physiological adaptation. Additionally, since our findings do not provide conclusive support for the manipulation of RST variables, further work is needed to better understand how programming factors can be manipulated to augment training-induced adaptations. STUDY REGISTRATION: Open Science Framework registration https://doi.org/10.17605/OSF.IO/RVNDW .

Does Moderate-Load Priming Activity Influence Maximal Upper-Body Performance and Perceptual State?

ABSTRACT: Harrison, PW, Kelly, VG, Jenkins, DG, McGuigan, MR, Holmberg, PM, and James, LP. Does moderate-load priming activity influence maximal upper-body performance and perceptual state?. J Strength Cond Res 37(11): e581-e587, 2023-The results of previous research indicate that resistance exercise "priming" may improve strength-power measures within 48 hours after their completion. Although researchers have primarily examined performance responses after lower-body priming stimuli, investigations examining the effects of upper-body resistance priming exercises are presently limited. Therefore, the aim of this study was to examine upper-body pushing and pulling performance in addition to perceptual responses 3 and 27 hours after moderate-load (ML) upper-body resistance priming exercise. Fourteen resistance-trained men were assigned to complete ML priming (4 × 3 bench press and bench pull at 65% 1RM [repetition maximum]) and control (rest) protocols in a randomized and counterbalanced order. Peak velocity during the bench throw and bench pull tests involving different loads (25, 50, and 75% 1RM) showed no practical change at 3 and 27 hours after the priming session (p = 0.216-0.99, Cliff's d = -0.041 to 0.225). Small effect size increases in perceptual measures ("physical feeling," "physical performance," "aggression" [p = 0.400-0.553, Cliff's d = 0.183-0.201], and "muscular heaviness" [p = 0.178, Cliff's d = 0.231]) were found at 3 hours postpriming. A moderate practical increase was observed in perceived "physical feeling" compared with control (p = 0.385, Cliff's d = 0.349) in addition to small effect size increases in perceived "physical performance" and "aggression" (Cliff's d = 0.243-0.290) at 27 hours after priming activities. These results indicate that upper-body strength-power changes within 27 hours after ML upper-body resistance exercise priming are not practically meaningful.

The Relationship Between Lower-Body Force-Time Variables and Skating Performance in Female Ice Hockey Players.

PURPOSE: Ice hockey is a team invasion sport characterized by repeated high-intensity skating efforts, technical and tactical skill, physical contact, and collisions requiring considerable levels of muscular strength. The purpose of this study was to evaluate the relationships between lower-body vertical force-time metrics and skating qualities in subelite female ice hockey players. METHODS: A cross-sectional cohort design was employed utilizing 14 athletes (body mass = 66.7 [1.8] kg; height = 171.6 [6.2] cm; age = 21.1 [1.7] y). The relationships between metrics of lower-body strength collected from a drop jump, squat jump, countermovement jump, loaded countermovement jump, and an isometric squat and 4 skating qualities collected from a linear sprint, repeated sprint test, and a multistage aerobic test were evaluated. RESULTS: The regression models revealed a positive relationship between relative peak force in the isometric squat and skating multistage aerobic test performance (r2 = .388; P = .017) and a positive relationship between repeated-sprint ability and eccentric mean force during the loaded countermovement jump (r2 = .595; P = .001). No significant relationships were observed between strength metrics and skating acceleration or maximal velocity. CONCLUSIONS: These data suggest that skating ability is most affected by relative isometric strength in female ice hockey players. It is recommended that practitioners focus training on tasks that improve relative force output. It is also recommended that isometric relative peak force be used as a monitoring metric for this cohort.

Common High-Speed Running Thresholds Likely Do Not Correspond to High-Speed Running in Field Sports.

ABSTRACT: Freeman, BW, Talpey, SW, James, LP, Opar, DA, and Young, WB. Common high-speed running thresholds likely do not correspond to high-speed running in field sports. J Strength Cond Res 37(7): 1411-1418, 2023-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.

Altered countermovement jump force profile and muscle-tendon unit kinematics following combined ballistic training.

Combined heavy- and light-load ballistic training is often employed in high-performance sport to improve athletic performance and is accompanied by adaptations in muscle architecture. However, little is known about how training affects muscle-tendon unit (MTU) kinematics during the execution of a sport-specific skill (e.g., jumping), which could improve our understanding of how training improves athletic performance. The aim of this study was to investigate vastus lateralis (VL) MTU kinematics during a countermovement jump (CMJ) following combined ballistic training. Eighteen young, healthy males completed a 10-week program consisting of weightlifting derivatives, plyometrics, and ballistic tasks under a range of loads. Ultrasonography of VL and force plate measurements during a CMJ were taken at baseline, mid-test, and post-test. The training program improved CMJ height by 11 ± 13%. During the CMJ, VL's MTU and series elastic element (SEE) length changes and velocities increased from baseline to post-test, but VL's fascicle length change and velocity did not significantly change. It is speculated that altered lower limb coordination and increased force output of the lower limb muscles during the CMJ allowed more energy to be stored within VL's SEE. This may have contributed to enhanced VL MTU work during the propulsion phase and an improved CMJ performance following combined ballistic training.

Investigating the sleep habits in individual and team-sport athletes using the Athlete Sleep Behavior Questionnaire and the Pittsburgh Sleep Quality Index.

Objectives: There is limited large-scale data on maladaptive sleep practices in elite adult athletes and their influence on sleep characteristics. This study aimed to identify differences in sleep behaviours between individual and team-sport athletes using two sleep questionnaires. Material and Methods: 407 (237 male, 170 female) elite adult athletes across sixteen sports (9 individual-sports, 7 team-sports) completed the Athlete Sleep Behavior Questionnaire (ASBQ) and the Pittsburgh Sleep Quality Index (PSQI). Results: Individual-sport athletes reported greater total sleep time and higher sleep efficiency than team-sport athletes (p<0.05, d=0.28-0.29). There were no differences between global scores for the PSQI, however, there was a difference between global scores for the ASBQ as well as multiple individual items from both questionnaires (p<0.05), indicating poorer behaviours in team-sport athletes. Discussion: Team-sport athletes displayed more maladaptive pre-sleep behaviours and poorer sleep characteristics than individual-sport athletes.

Rate of Force Development Adaptations After Weightlifting-Style Training: The Influence of Power Clean Ability.

ABSTRACT: James, LP, Suchomel, TJ, Comfort, P, Haff, GG, and Connick, M. Rate of force development adaptations after weightlifting-style training: the influence of power clean ability. J Strength Cond Res 36(6): 1560-1567, 2022-This experiment examined changes to the rate of force development (RFD) expressed under loaded jump conditions between individuals with a higher (stronger) and lower (weaker) weightlifting performance (as assessed by the 1 repetition maximum [RM] power clean) after training with the weightlifting derivatives. Two groups of markedly different weightlifting ability undertook 10 weeks of training with the power clean variants, snatch pulls, and jump squats across heavy and light conditions. Testing was performed at baseline, after 5 weeks of training (mid-test) and after training (post-test). During testing, RFD was assessed under a series of loads (20-80% squat 1RM) through the jump squat. Furthermore, the force-velocity relationship, and unloaded jump strategy (through the force-time curve waveform), were also examined. Very large change (Hedge's g, 95% confidence interval [g] = 2.10, 1.24 to 4.16) in RFD at 20% 1RM at mid-test occurred within the stronger group. Conversely, a small increase (g = 0.27, 0.53-1.91) among the weaker subjects existed in this measure at mid-test, reaching a moderate increase at post-test (g = 0.71, -0.18 to 2.15). Limited improvements were seen by the stronger subjects in RFD at 60 and 80% 1RM at either mid-test (60%: g = 0.27, -0.75 to 1.33; 80% = 0.02, -1.01 to 1.00) or post-test (60%: g = 0.52, -0.38 to 1.80; 80% = -0.26, -1.23 to 0.77). The stronger group experienced a shift throughout the force-velocity relationship while a more force-dominant adaptation occurred in weaker subjects. Differences in jump strategy between groups were also noted. Such training will elicit practically different adaptations in rapid force production depending on the individual's baseline weightlifting ability.

The reliability of novel, temporal-based dynamic strength index metrics.

The purpose of this study was: i) to determine the reliability of alternate forms of the dynamic strength index (DSI) calculated over time-specific intervals that represent decisive actions in sport and ii) to assess the association between the original form of the DSI (DSItrad) and its variants. Twenty-three resistance-trained males (BM = 80.4 ± 10.18 kg; age = 26.3 ± 10.2 y; 1-RM squat kg/kg/BM = 1.61 ± 0.37) performed trials of the countermovement jump (CMJ) and isometric squat. Several variations of the DSI were calculated by dividing the mean force in the CMJ by the mean force in the isometric squat calculated over the following epochs: 100 ms (DSI100), 150 ms (DSI150) and CMJ propulsive phase duration (DSIprop). In the fourth method, mean force across the CMJ propulsive phase duration was divided by mean force in the isometric squat between initiation and peak force (DSIpeak). All alternate DSI measures achieved acceptable absolute reliability (CV < 10%), however they did not achieve at least a moderate relative reliability. DSIprop (R2 = 0.41), DSI100 (R2 = 0.03) and DSI150 (R2 = 0.14) demonstrated limited commonality with DSItrad. The alternate forms of DSI can cautiously be considered in strength assessment systems.

Similar Morphological and Functional Training Adaptations Occur Between Continuous and Intermittent Blood Flow Restriction.

ABSTRACT: Davids, CJ, Raastad, T, James, L, Gajanand, T, Smith, E, Connick, M, McGorm, H, Keating, S, Coombes, JS, Peake, JM, and Roberts, LA. Similar morphological and functional training adaptations occur between continuous and intermittent blood flow restriction. J Strength Cond Res 35(7): 1784-1793, 2021-The aim of the study was to compare skeletal muscle morphological and functional outcomes after low-load resistance training using 2 differing blood flow restriction (BFR) protocols. Recreationally active men and women (n = 42 [f = 21], 24.4 ± 4.4 years) completed 21 sessions over 7 weeks of load-matched and volume-matched low-load resistance training (30% 1 repetition maximum [1RM]) with either (a) no BFR (CON), (b) continuous BFR (BFR-C, 60% arterial occlusion pressure [AOP]), or (c) intermittent BFR (BFR-I, 60% AOP). Muscle mass was assessed using peripheral quantitative computed tomography before and after training. Muscular strength, endurance, and power were determined before and after training by assessing isokinetic dynamometry, 1RM, and jump performance. Ratings of pain and effort were taken in the first and final training session. An alpha level of p < 0.05 was used to determine significance. There were no between-group differences for any of the morphological or functional variables. The muscle cross sectional area (CSA) increased pre-post training (p = 0.009; CON: 1.6%, BFR-C: 1.1%, BFR-I: 2.2%). Maximal isometric strength increased pre-post training (p < 0.001; CON: 9.6%, BFR-C: 14.3%, BFR-I: 19.3%). Total work performed during an isokinetic endurance task increased pre-post training (p < 0.001, CON: 3.6%, BFR-C: 9.6%, BFR-I: 11.3%). Perceptions of pain (p = 0.026) and effort (p = 0.033) during exercise were higher with BFR-C; however, these reduced with training (p = 0.005-0.034). Overall, these data suggest that when 30% 1RM loads are used with a frequency of 3 times per week, the addition of BFR does not confer superior morphological or functional adaptations in recreationally active individuals. Furthermore, the additional metabolic stress that is proposed to occur with a continuous BFR protocol does not seem to translate into proportionally greater training adaptations. The current findings promote the use of both intermittent BFR and low-load resistance training without BFR as suitable alternative training methods to continuous BFR. These approaches may be practically applicable for those less tolerable to pain and discomfort associated with ischemia during exercise.

Time Course of Neuromuscular, Hormonal, and Perceptual Responses Following Moderate- and High-Load Resistance Priming Exercise.

PURPOSE: The aim of this study was to map responses over 32 hours following high-load (HL) and moderate-load (ML) half-squat priming. METHODS: Fifteen participants completed control, HL (87% 1RM), and ML (65% 1RM) activities in randomized, counterbalanced order. Countermovement jump (CMJ), squat jump (SJ), saliva testosterone, saliva cortisol, and perceptual measures were assessed before and 5 minutes, 8 hours, 24 hours, and 32 hours after each activity. Results are presented as percentage change from baseline and 95% confidence interval (CI). Cliff delta was used to determine threshold for group changes. RESULTS: SJ height increased by 4.5% (CI = 2.2-6.8, Cliff delta = 0.20) 8 hours following HL. CMJ and SJ improved by 6.1% (CI = 2.1-7.8, Cliff delta = 0.27) and 6.5% (CI = 1.2-11.8, Cliff delta = 0.30), respectively, 32 hours after ML. No clear diurnal changes in CMJ or SJ occurred 8 hours following control; however, increases of 3.9% (CI = 2.9-9.2, Cliff delta = 0.26) and 4.5% (CI = 0.9-8.1, Cliff delta = 0.24), respectively, were observed after 32 hours. Although diurnal changes in saliva hormone concentration occurred (Cliff delta = 0.37-0.92), the influence of priming was unclear. Perceived "physical feeling" was greater 8 hours following HL (Cliff delta = 0.36) and 32 hours after ML and control (Cliff delta = 0.17-0.34). CONCLUSIONS: HL priming in the morning may result in small improvements in jump output and psychophysiological state in the afternoon. Similar improvements were observed in the afternoon the day after ML priming.