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Objective: the purpose of this study was to identify differences in hamstring passive stiffness between the pre-season and in-season periods., Methods: Hamstring strength and passive stiffness were measured in professional male soccer players before and after the pre-season (4 weeks), and after the in-season (6 weeks) periods using an isokinetic dynamometer. Muscle passive stiffness was determined from the slope of the passive torque-angle relationship. External loads (acceleration and jumps) were monitored by GPS and internal loads by questionnaire., Results: Hamstring passive stiffness increased after 10 weeks of training and matches, without changes in passive peak torque and range of motion. The hamstring passive stiffness modifications were associated with the volume and intensity of accelerations and jumps. The individual data analysis also provided some support for the suppression of the biomechanical adaptation in the subjects with relatively large external load., Conclusions: Regular training and match workouts increase hamstring passive stiffness in professional soccer players but the adaptation of muscle-tendon unit passive elements might not occur if players experience excessive mechanical stress., Competing Interests: The authors have no conflict of interest.

An understanding of how movement competency, strength, and power interact with natural growth and maturation is required in order to determine meaningful changes with developing athletes. Isometric and dynamic testing in youth athletes provides insight into the natural development of the force-velocity (F-V) spectrum. Two-hundred and six young male athletes, aged 9-17 years of age, were grouped according to stage of maturation based on their maturity offset which was determined as number of years from peak height velocity (PHV). All participants performed the back-squat assessment (BSA), isometric mid-thigh pull (IMTP), countermovement jump (CMJ), and squat jump (SJ) tests. Absolute and scaled force-time variables were collected from the IMTP, CMJ, and SJ. No significant differences were observed between maturational groups for squat movement competency (P > .05). One-way ANOVA with Bonferroni post-hoc analysis revealed that increasing maturity led to significant, moderate to large increases in allometrically scaled peak force (PF allo ) for all tests (P < .05). Multiple stepwise linear regression models revealed IMTP PF allo significantly predicted 34.8% and 41.3% of variance in SJ and CMJ jump height, respectively (P < .05). Natural growth and maturation induces positive adaptations to movement competency as well as isometric and dynamic strength and power. Trends from the IMTP, SJ, and CMJ tests indicate the largest differences in strength, and power may occur around the adolescent growth spurt despite the large variation in rates of change within the circa-PHV group., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objectives: To explore associations between measures of lower limb muscle force, velocity and power from jumping mechanography (JM) and simple physical capability (PC) testing, and falls in community dwelling older adults., Methods: Participants performed a two-leg countermovement jump on a ground reaction force platform. Jump force, power and velocity were calculated. PC tests were 6m timed-up-and-go (TUG)(sec), grip strength (kg), gait speed (m/s) and chair rise time (secs). Two-three years after JM and PC testing, self-reported falls in the previous year were recorded, and logistic regression analysis used to determine whether JM and PC measures were associated with falls., Results: Fall and PC data were available for 258 (169 JM) participants. Mean (SD) age at baseline was 75(2.5) years, 50% (n=129) were women and 27% (n=70) had fallen. As power and velocity increased, the odds of being a faller decreased [(odds ratio (OR)=0.91, 95% confidence interval (CI) 0.85,0.98] and (OR=0.20, 95% CI 0.05 0.72) respectively). Whilst grip strength and TUG were associated with falling; relationships were attenuated after adjustment., Conclusions: Jumping mechanography-measured muscle power and velocity were associated with lower risk of falls. In this relatively healthy cohort of older adults JM appears to be more sensitive measure of muscle deficits and falls risk than standard PC measures., Competing Interests: Professor Cyrus Cooper has received lecture fees and honoraria from Amgen, Danone, Eli Lilly, GSK, Kyowa Kirin, Medtronic, Merck, Nestlé, Novartis, Pfizer, Roche, Servier, Shire, Takeda and UCB outside of the submitted work. Camille M Parsons, Mark H Edwards, Elaine M Dennison and Kate A Ward have nothing to disclose.

Purpose: To summarize the evidence on postactivation potentiation (PAP) protocols using flywheel eccentric overload (EOL) exercises., Methods: Studies were searched using the electronic databases PubMed, Scopus, and Institute for Scientific Information Web of Knowledge., Results: In total, 7 eligible studies were identified based on the following results: First, practitioners can use different inertia intensities (eg, 0.03-0.88 kg·m2), based on the exercise selected, to enhance sport-specific performance. Second, the PAP time window following EOL exercise seems to be consistent with traditional PAP literature, where acute fatigue is dominant in the early part of the recovery period (eg, 30 s), and PAP is dominant in the second part (eg, 3 and 6 min). Third, as EOL exercises require large force and power outputs, a volume of 3 sets with the conditioning activity (eg, half-squat or lunge) seems to be a sensible approach. This could reduce the transitory muscle fatigue and thereby allow for a stronger potentiation effect compared with larger exercise volumes. Fourth, athletes should gain experience by performing EOL exercises before using the tool as part of a PAP protocol (3 or 4 sessions of familiarization). Finally, the dimensions of common flywheel devices offer useful and practical solutions to induce PAP effects outside of normal training environments and prior to competitions., Conclusions: EOL exercise can be used to stimulate PAP responses to obtain performance advantages in various sports. However, future research is needed to determine which EOL exercise modalities among intensity, volume, and rest intervals optimally induce the PAP phenomenon and facilitate transfer effects on athletic performances.

Purpose: This study aimed at investigating how prior knowledge of drop heights affects proactive and reactive motor control in drop jumps (DJ)., Methods: In 22 subjects, the effect of knowledge of three different drop heights (20, 30, 40 cm) during DJs was evaluated in seven conditions: three different drop heights were either known, unknown or cheated (announced 40 cm, but actual drop height was 20 cm). Peak ground reaction force (F max ) to body weight (BW) ratio (F max /BW) and electromyographic (EMG) activities of three shank and five thigh muscles were assessed 150 ms before and during ground contact (GC). Ankle, knee and hip joint kinematics were recorded in the sagittal plane., Results: Leg stiffness, proactive and reactive EMG activity of the leg muscles diminished in unknown and cheat conditions for all drop heights (7-33% and 2-26%, respectively). Antagonistic co-activation increased in unknown (3-37%). At touchdown, increased flexion in knee (~ 5.3° ± 1.9°) and hip extension (~ 2° ± 0.6°) were observed in unknown, followed by an increased angular excursion in hip (~ 2.3° ± 0.2°) and knee joints (~ 5.6° ± 0.2°) during GC (p < 0.05). Correlations between changes in activation intensities, joint kinematics, leg stiffness and F max /BW (p < 0.05) indicate that anticipation changes the neuromechanical coupling of DJs. No dropouts were recorded., Conclusion: These findings underline that anticipation influences timing and adjustment of motor responses. It is argued that proactive and reactive modulations associated with diminished activation intensities in leg extensors are functionally relevant in explaining changes in leg stiffness and subsequent decline in performance.

Purpose: Resistance training is often performed in a traditional training style using deliberate relatively longer repetition durations or in an explosive training style using maximal intended velocities and relatively shorter repetition durations. Both improve strength, "power" (impulsivity), and speed. This study compared explosive and traditional training over a 6-week intervention in 30 healthy young adult male recreational soccer players., Method: Full body supervised resistance training was performed 2 times a week using 3 sets of each exercise at 80% of one repetition maximum to momentary failure. Outcomes were Smith machine squat 1 repetition maximum, 10 meter sprint time, and countermovement jump., Results: Both groups significantly improved all outcomes based on 95% confidence intervals not crossing zero. There were no between-group differences for squat 1 RM (TRAD = 6.3[5.1 to 7.6] kg, EXP = 5.2[3.9 to 6.4] kg) or 10 meter sprint (TRAD = -0.05[-0.07 to -0.04] s, EXP = -0.05[-0.06 to -0.03] s). Explosive group had a significantly greater increase in countermovement jump compared to the traditional group (TRAD = 0.7[0.3 to 1.1] cm, EXP = 1.3[0.9 to 1.7] cm)., Conclusion: Both the traditional training and explosive training performed to momentary failure produced significant improvements in strength, speed, and jump performance. Strength gains are similar independent of intended movement speed. However, speed and jump performance changes are marginal with resistance training.

Purpose: Self-myofascial release (SMFR) is a type of self-massage that is becoming popular among athletes. However, SMFR's effects on running performance have not yet been investigated. The aim of this study was to evaluate the effects of SMFR on the cost of running (Cr). In addition, the authors evaluated the effects of SMFR on lower-limb muscle power., Methods: Cr and lower-limb muscle power during squat jump (SJ) and countermovement jump (CMJ) were measured before (PRE), immediately after (POST), and 3 h after (POST 3h) an SMFR protocol (experimental condition). In the control-condition testing session, the same measurements were performed without undergoing the SMFR protocol. Experimental and control conditions were tested in a randomized order., Results: Cr at POST trended to increase compared with PRE (+6.2% [8.3%], P = .052), whereas at POST 3h, Cr was restored to PRE values (+0.28% [9.5%], P = .950). In the experimental condition, no significant effect of time was observed for maximal power exerted during SJ. By contrast, maximal power exerted during CMJ at POST and at POST 3h was significantly higher than that observed at PRE (+7.9% [6.3%], P = .002 and +10.0% [8.7%], P = .004, respectively). The rate of force development measured during CMJ also increased after SMFR, reaching statistical significance at 200 ms from force onset at POST 3h (+38.9%, P = .024)., Conclusions: An acute use of foam rollers for SMFR performed immediately prior to running may negatively affect endurance running performance, but its use should be added before explosive motor performances that include stretch-shortening cycles.

This study quantified lower-limb strength decrements and assessed the relationships between strength decrements and performance fatigue during simulated basketball. Ten adolescent, male basketball players completed a circuit-based, basketball simulation. Sprint and jump performance were assessed during each circuit, with knee flexion and extension peak concentric torques measured at baseline, half-time, and full-time. Decrement scores were calculated for all measures. Mean knee flexor strength decrement was significantly (P < 0.05) related to sprint fatigue in the first half (R = 0.65), with dominant knee flexor strength (R = 0.67) and dominant flexor:extensor strength ratio (R = 0.77) decrement significantly (P < 0.05) associated with sprint decrement across the entire game. Mean knee extensor strength (R = 0.71), dominant knee flexor strength (R = 0.80), non-dominant knee flexor strength (R = 0.75), mean knee flexor strength (R = 0.81), non-dominant flexor:extensor strength ratio (R = 0.71), and mean flexor:extensor strength ratio (R = 0.70) decrement measures significantly (P < 0.05) influenced jump fatigue during the entire game. Lower-limb strength decrements may exert an important influence on performance fatigue during basketball activity in adolescent, male players. Consequently, training plans should aim to mitigate lower-limb fatigue to optimise sprint and jump performance during game-play.

Objective: To determine normative values for weight-bearing, countermovement leg extension ("jump") tests in the oldest men and characteristics of those not completing vs. completing tests., Design: 2014-16 cross-sectional exam., Setting: Six U.S. sites from the Osteoporotic Fractures in Men (MrOS) Study., Participants: Community-dwelling men (N=1,841) aged 84.5±4.2 (range: 77-101) years., Interventions: N/A., Measurements: Jump tests on a force plate measured lower-extremity muscle peak power/kg, velocity and force/kg at peak power, with normative values for 5-year age groups and by limitations in moderate-intensity activities of daily living (ADLs) and climbing several flights of stairs., Results: Jump completion was 68.9% (N=1,268/1,841) and 98% (1,242/1,268) had ≥1 analyzable trial/participant. Exclusions primarily were due to poor mobility and/or balance: 24.8% (456/1,841) prior to and 6.4% (N=117/1,841) after attempting testing. Peak power was 20.8±5.3 W/kg, with 1.2±0.3 m/s for velocity, and 16.7±1.9 N/kg for force at peak power. Each 5-year age group >80 years had subsequently 10% lower power/kg, with 30% lower power/kg at >90 vs. ≤80 years (all p<0.05). Velocity and force/kg at peak power were 24% and 9% lower respectively, at >90 vs. ≤80 years (all p<0.05). Limitations in both moderate ADLs and climbing several flights of stairs were associated with 16% lower age-adjusted power/kg, equivalent to 5-10 years of aging, with 11% and 6% lower age-adjusted velocity and force/kg respectively, vs. those without limitation (all p<0.05). Men not completing vs. completing jumps had older age, higher BMI, lower physical activity, more comorbidities, worse cognition, more IADLs/ADLs and more falls in the past year (all p<0.05). Post-jump pain occurred in 4.6% (58/1,268), with 2 participants stopping testing due to pain. Only 24/1,242 (2%) had all trials/participant without flight (i.e., inability to lift feet), with 323/1,242 having ≥1 trial/participant without flight (total of 28%). No serious adverse safety events (e.g., injury) occurred., Conclusions: A multicenter cohort of oldest men with a range of function had higher declines in jump power/kg and velocity vs. force/kg across each 5-year age group >80 years. Future research should examine age- and functional-related declines in jump measures related to physical performance decline, falls, fractures, and disability., Competing Interests: None of the authors have disclosures

Objectives: We aimed to determine whether countermovement jumps (CMJs; unilateral and bilateral) performed in different directions assessed independent lower-limb power qualities, and if unilateral CMJs would better differentiate between elite and non-elite soccer players than the bilateral vertical (BV) CMJ., Design: Elite (n=23; age, 18.1±1.0years) and non-elite (n=20; age, 22.3±2.7years) soccer players performed three BV, unilateral vertical (UV), unilateral horizontal-forward (UH) and unilateral medial (UM) CMJs., Methods: Jump performance (height and projectile range), kinetic and kinematic variables from ground reaction forces, and peak activation levels of the vastus lateralis and biceps femoris (BF) muscles from surface electromyography, were compared between jumps and groups of players., Results: Peak vertical power (V-power) was greater in BV (220.2±30.1W/kg) compared to UV (144.1±16.2W/kg), which was greater than UH (86.7±18.3W/kg) and UM (85.5±13.5W/kg) (all, p<0.05) but there was no difference between UH and UM (p=1.000). Peak BF EMG was greater in UH compared to all other CMJs (p≤0.001). V-power was greater in elite than non-elite for all CMJs (p≤0.032) except for BV (p=0.197). Elite achieved greater UH projectile range than non-elite (51.6±15.4 vs. 40.4±10.4cm, p=0.009)., Conclusions: We have shown that UH, UV and UM CMJs assess distinct lower-limb muscular power capabilities in soccer players. Furthermore, as elite players outperformed non-elite players during unilateral but not BV CMJs, unilateral CMJs in different directions should be included in soccer-specific muscular power assessment and talent identification protocols, rather than the BV CMJ., (Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

This study evaluates the effect of 3 months resistance and aerobic training on muscle strength and power in 17 male overweight and obese men. Subjects underwent either a resistance or aerobic training for a period of 3 months (three sessions per week). Peak isometric force, rate of force development, peak power and height of countermovement and squat jumps, reactive strength index, and mean power in the concentric phase of bench presses were all assessed prior to and after completing the training program. Results identified a significant increase of mean power during both countermovement bench presses at 30 kg (18.6%, p = .021), 40 kg (14.6%, p = .033), and 50 kg (13.1%, p = .042) and concentric-only bench presses at 30 kg (19.6%, p = .017) and 40 kg (13.9%, p = .037) after the resistance training. There was also a significant increase in the height of the jump (12.8%, p = .013), peak power (10.1%, p = .026), and peak velocity (9.7%, p = .037) during the countermovement jump and height of the jump (11.8%, p = .019), peak power (9.6%, p = .032), and peak velocity (9.5%, p = .040) during the squat jump. There were no significant changes in the reactive strength index, peak force, and the rate of force development after the resistance training. The aerobic group failed to show any significant improvements in these parameters. It may be concluded that 3 months of resistance training without caloric restriction enhances upper and lower body muscle power in overweight and obese men.

The purpose of this study was to examine relationships between pre-training psychological well-being assessment scales (General Health Questionnaire-28-GHQ-28, Competitive State Anxiety Inventory-2-CSAI-2, Sport Competition Anxiety Test-SCAT, State-Trait Anxiety Inventory-S-STAI-S, Oviedo Sleep Questionnaire-OSQ and Psychological Characteristics Related to Sport Performance-PCSP), and pre-training stress hormone concentrations (cortisol-C, total testosterone-TT, free testosterone-FT, adrenocorticotropic hormone-ACTH and testosterone/cortisol-T/C ratios), on acute neuromuscular performance (ANP) in female volleyballers. Forty elite female volleyballers (27±4yrs.; 178.3±8.5cm; 67.9±7.2kg) participated. Bivariate correlations were performed between psychological assessments and hormone levels with ANP. All psychological scales presented at least one significant (p<0.05) relationship or prediction of ANP. Contrastingly, among hormones, the only significant relationship was between TT/C ratio and Overhead Medicine Ball Throw (r=0.34; p<0.05). Therefore, our data shows that results of general and sport-specific psychological well-being scales prior to training are more consistently related to performance in elite female volleyballers than pre-training stress hormone concentrations., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Purpose: Previous research has investigated changes in athletes' strength, power, and speed performances across the competitive season of many sports, although this has not been explored in cricketers. The aim of this study was to investigate changes in lower-body strength and jump and sprint performances across an English county cricket season., Methods: Male cricketers (N = 12; age 24.4 ± 2.3 y, body mass 84.3 ± 9.9 kg, height 184.1 ± 8.1 cm) performed countermovement jumps (CMJs) and 20-m sprints on 4 separate occasions and back-squat strength testing on 3 separate occasions across a competitive season., Results: Both absolute (12.9%, P = .005, effect size [ES] = 0.53) and relative lower-body strength (15.8%, P = .004, ES = 0.69) and CMJ height (5.3%, P = .037, ES = 0.42) improved significantly over the preseason training period, although no significant change (1.7%, P > .05) in sprint performance was observed. In contrast, absolute (14.3%, P = .001, ES = 0.72) and relative strength (15.0%, P = .001, ES = 0.77), CMJ height (4.2%, P = .023, ES = 0.40), and sprint performance (3.8%, P = .012, ES = 0.94) declined significantly across the season., Conclusions: The results of this study show that neither the demands of the competitive cricket season nor current in-season training practices provide a sufficient stimulus to maintain strength, jump, and sprint performances in these cricketers. Therefore, coaches should implement a more-frequent, higher-load strength-training program across the competitive cricket season.

This study aimed to compare the effects of 8-week combined vertical-oriented vs. horizontal-oriented training interventions in basketball athletes. Eighteen highly trained U-16 basketball players participated in this study and were randomly assigned to either a combined vertical-oriented training group (CVG, n = 9) or a combined horizontal-oriented training group (CHG, n = 9). Bilateral and unilateral vertical jump height, unilateral horizontal jump distance, 5-m, 10-m, and 20-m sprint times, change- of-direction sprint times, and a limb symmetry index were among the measured performance variables. Combined strength training was performed twice a week for 8 weeks. CVG was compounded by the squat exercise (3 sets of 6-8 R at 30-45% 1 repetition maximum [1RM]), jump squats (2 sets of 6 R, at 5-12.5% body mass [BM]), and vertical jumps (3-4 sets × 6 R). CHG included the hip thrust exercise (3 sets of 6-8 R at 30-45% 1RM), sled towing sprints (2-3 R, at 5-12.5% BM), and sprints (3-4 R of 20-m). Within-group differences showed significant (p < 0.05 and statistical power >80%) improvements in unilateral vertical jumping with the right leg after both training interventions. By contrast, only CHG improved 5-m, 10-m, and 20-m sprint times (p < 0.05 and statistical power >80%). Significant effects were observed for CHG compared with CVG in 5-m, 10-m, and 20-m sprint times (p < 0.05 and statistical power >80%). This study reinforces the importance of oriented-combined training based on force-vector specificity target, mainly in horizontal-oriented actions. [ABSTRACT FROM AUTHOR]

Background Verbal and tactile cues can increase muscle activity, force production, and kinematics. Several studies demonstrate the effects of verbal and tactile cues on upper extremity muscles, while relatively few examined lower extremity muscles, specifically the gluteals. Studies that observed changes in gluteal function from verbal and tactile cues examined muscle activity via electromyography rather than force production or functional activities such as jumping. Purpose The purpose of this study was to measure the effects of verbal and tactile cues on gluteal force production and broad jump distance. Study Design Cross-Sectional cohort Methods Gluteus maximus force production and broad jump distance were tested in forty-two healthy male and female university students at baseline and after verbal and tactile cues given in random order. Gluteus maximus force was measured using handheld dynamometry and reported in kilograms. Verbal cues included "push, push, push" before both tests. The examiner provided tactile cues to the gluteus maximus before force production testing, and the participant provided tactile cues to both gluteus maximus muscles before performing the broad jump. Performance on the broad jump was measured in centimeters. Descriptive statistics and test-retest reliability via Pearson correlation coefficients were calculated, differences in performance between sexes were analyzed with an independent t-test, and changes in force production and jump distance from baseline were analyzed using a one-way ANOVA. Results Mean gluteus maximus force production following verbal cues significantly increased (p = 0.000) by 13.48% (3.83 kg) compared to the control condition, while gluteal force production following the tactile cues was not significantly different. Broad jump distance following the verbal cues significantly increased (p = 0.000) 3.99% (7.71 cm) compared to the control condition and significantly increased (p = 0.000) by 2.95% (5.71 cm) following the tactile cues. There were no significant differences in performances between males and females. The test-retest reliability of all measurements was 0.97-0.99. Conclusion Verbal cues significantly increased gluteus maximus force production and broad jump distance. Tactile cues significantly increased broad jump distance but had no significant effect on gluteus maximus force. These results have implications for clinical testing and athletic performance when gluteus maximus force and jump distance are concerned. Level of Evidence 3 [ABSTRACT FROM AUTHOR]

BACKGROUND: Foot arch dynamics play an important role in dynamic postural control. Association between foot arch dynamics and postural control among adolescent athletes remains poorly explored. OBJECTIVE: To examine the relationship between foot arch dynamics, intrinsic foot muscle (IFM) morphology, and toe flexor strength and dynamic postural stability after jump landing and repetitive rebound jump performance in competitive adolescent athletes. METHODS: Based on foot arch dynamics, evaluated from relative change in the foot arch height in sitting and standing positions, 50 adolescent athletes were classified as stiff, normal, or flexible. IFM morphology was evaluated by ultrasonography. Dynamic postural stability index (DPSI) was measured as participants jumped and landed with the right leg onto a force plate, whereas repetitive rebound jumping performance was assessed using the jump height and reactive jump index. RESULTS: The stiff group had a significantly worse DPSI and vertical stability index than the normal group (p = 0.26, p = 0.44, respectively), and worse anteroposterior stability index (APSI) values than the flexible group (p = 0.005). Multivariate regression models of the relationship between the APSI and foot arch dynamics showed adequate power (probability of error = 0.912). CONCLUSIONS: Increased foot arch stiffness negatively affects dynamic balance during jump-landing, which may deteriorate their performance. [ABSTRACT FROM AUTHOR]

Research on the evolution of performance throughout a season in team sports is scarce and mainly focused on men's teams. Our aim in this study was to examine the seasonal variations in relevant indices of physical performance in female football players. Twenty-seven female football players were assessed at week 2 of the season (preseason, PS), week 7 (end of preseason, EP), week 24 (half-season, HS), and week 38 (end of season, ES). Similar to the most common used conditioning tests in football, testing sessions consisted of (1) vertical countermovement jump (CMJ); (2) 20 m running sprint (T20); (3) 25 m side-step cutting maneuver test (V-CUT); and (4) progressive loading test in the full-squat exercise (V1-LOAD). Participants followed their normal football training procedure, which consisted of three weekly training sessions and an official match, without any type of intervention. No significant time effects were observed for CMJ height (p = 0.29) and T20 (p = 0.11) throughout the season. However, significant time effects were found for V-CUT (p = 0.004) and V1-LOAD (p = 0.001). V-CUT performance significantly improved from HS to ES (p = 0.001). Significant increases were observed for V1-LOAD throughout the season: PS-HS (p = 0.009); PS-ES (p < 0.001); EP-ES (p < 0.001); and HS-ES (p = 0.009). These findings suggest that, over the course of the season, female football players experience an enhancement in muscle strength and change of direction ability. However, no discernible improvements were noted in sprinting and jumping capabilities during the same period. [ABSTRACT FROM AUTHOR]

Purpose: This study established the relationship between isometric midthigh pull (IMTP) peak force and court-based jumping, sprinting, and change of direction (COD) performance in professional netball players. The change in IMTP peak force in response to sport-specific training was also examined. Methods: IMTP peak force and court-based jumping, sprinting, and COD were collected in 18 female athletes contracted to a Suncorp Super Netball team. Linear regression models established the relationship between absolute and normalized strength values and court-based performance measures in the participant cohort. Changes in IMTP peak force and court-based performance measures were examined following 2 consecutive preseason training blocks in a subset of participants. Results: The IMTP peak force values normalized to body mass were found to be determinants of court-based jumping, sprinting, and COD performance in the participant cohort (R2 =.34–.65, P ≤.016). The participants showed increases in absolute (mean ± SE = 398 ± 68.5 N, P <.001, Hedge g = 0.70 [−0.05 to 1.35]) and normalized IMTP peak force (mean ± SE = 4.6 ± 0.78 N·kg−1, P <.001, Hedge g = 0.47 [−0.04 to 0.97]) over 2 consecutive training blocks that coincided with improvements in jumping, sprinting, and COD performances. Conclusion: IMTP peak force is a determinant of court-based jumping, sprinting, and COD performance and is sensitive to training in professional netball players. These results support the utility of the IMTP test to monitor the development and maintenance of maximal lower body muscular strength in these athletes. [ABSTRACT FROM AUTHOR]

The combination of strength training with complementary wholebody electromyostimulation (WB-EMS) and plyometric exercises has been shown to increase strength and jumping performance in athletes. In elite sport, however, the mesocycles of training are often organized according to block periodization. Furthermore, WB-EMS is often applied onto static strength exercises, which may hamper the transfer into more sport-specific tasks. Thus, this study aimed at investigating whether four weeks of strength training with complementary dynamic vs. static WBEMS followed by a four-week block of plyometric training increases maximal strength and jumping performance. A total of n = 26 (13 female/13 male) trained adults (20.8 ± 2.2 years, 69.5 ± 9.5kg, 9.7 ± 6.1h of training/w) were randomly assigned to a static (STA) or volume-, load- and work-to-rest-ratio-matched dynamic training group (DYN). Before (PRE), after four weeks (three times weekly) of WB-EMS training (MID) and a subsequent fourweek block (twice weekly) of plyometric training (POST), maximal voluntary contraction (MVC) at leg extension (LE), leg curl (LC) and leg press machines (LP) and jumping performance (SJ, Squat Jump; CMJ, counter-movement-jump; DJ, drop-jump) were assessed. Furthermore, perceived effort (RPE) was rated for each set and subsequently averaged for each session. MVC at LP notably increased between PRE and POST in both STA (2335 ± 539 vs. 2653 ± 659N, standardized mean difference [SMD] = 0.528) and DYN (2483 ± 714N vs. 2885 ± 843N, SMD = 0.515). Reactive strength index of DJ showed significant differences between STA and DYN at MID (162.2 ± 26.4 vs. 123.1 ± 26.5 cms- 1, p = 0.002, SMD = 1.478) and POST (166.1 ± 28.0 vs. 136.2 ± 31.7 cms-1, p = 0.02, SMD = 0.997). Furthermore, there was a significant effect for RPE, with STA rating perceived effort higher than DYN (6.76 ± 0.32 vs. 6.33 ± 0.47 a.u., p = 0.013, SMD = 1.058). When employing a training block of high-density WB-EMS both static and dynamic exercises lead to similar adaptations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Chronic ankle instability (CAI) has a higher frequency in soccer due to the rapid changes in body movement. Thus, this study compared the effects of eight weeks of a hopping protocol and a combined protocol of balance plus strength in a within-between group analysis. Thirty-six male professional soccer players participated in this study and were randomly allocated in three groups: control group (CG, n = 12), hopping group (HG, n = 12), and balance plus strength group (BSG, n = 12). Strength, static and dynamic balance, and function were assessed at baseline and eight weeks post intervention. First, Foot and Ankle Ability Measure (FAAM) and FAAM sport scales were applied. Then, a dynamometer was used to measure strength of the muscles around the hip, knee, and ankle joints. The Bass stick measured static balance and the Y balance test measured dynamic balance. Additionally, functional tests were carried out by Triple Hop, the Figure 8 hop, and vertical jump. A repeated measures ANOVA [(3 groups) × 2 moments] was used to compare the within and between group differences. In general, all tests improved after eight weeks of training with both protocols. Specifically, the BSG improved with large ES for all tests, while the HG improved all test with small to large effect sizes (ES). Furthermore, HG showed higher values for vertical jump (p < 0.01, ES = 1.88) and FAAMSPORT (p < 0.05, ES = 0.15) than BSG. BSG showed higher values for hip abduction (p < 0.05, ES = 2.77), hip adduction (p < 0.05, ES = 0.87), and ankle inversion (p < 0.001, ES = 1.50) strength tests, while HG showed higher values for knee flexion [ES = 0.86, (0.02, 1.69)] and ankle plantarflexion [ES = 0.52, (−0.29, 1.33)]. Balance plus strength protocol showed more positive effects than the hopping protocol alone for soccer players with CAI. [ABSTRACT FROM AUTHOR]

Bipedal hopping has the potential to detect subtle multiple sclerosis (MS)-related impairments, especially among patients who "pass" typical movement tests. In this narrative review, we outline the biomechanics of bipedal hopping and propose its usefulness as a novel outcome measure for people with MS having mild disability. We summarize articles that (1) examined the biomechanics of jumping or hopping and (2) tested the validity and/or reliability of hopping tests. We consolidated consistencies and gaps in research and opportunities for future development of the bipedal hop test. Bipedal hopping requires immense power, coordination, balance, and ability to reduce co-contraction; movement components typically affected by MS. These impairments can be measured and differentiated by examining specific variables, such as hop length (power), symmetry (coordination), center of pressure (balance), and coefficient of variability (co-contraction/spasticity). Bipedal hopping challenges these aspects of movement and exposes sensorimotor impairments that may not have been apparent during walking. Testing of bipedal hopping on an instrumented walkway may detect and monitor sensorimotor control in people with MS who do not currently present with clinical deficits. Early measurement is imperative for precise rehabilitation prescription to slow disability progression prior to onset of measurable gait impairment. Jumping and hopping tests detect lower limb and balance impairments in children, athletes, and older adults. Bipedal hop test measures multiple domains: power, coordination, balance, and muscle timing. Bipedal hop test may expose subtle sensorimotor impairments in people with multiple sclerosis. Multiple variables measured can discern type of sensorimotor impairment to direct personalized rehabilitation programs. [ABSTRACT FROM AUTHOR]

Heritability studies on sport-related traits accepted that endurance, speed, power, and strength abilities include an active genetic predisposition to elite soccer participation. This study evaluates the influence of selected genetic variants on performance in speed, power, and strength laboratory tests on a group of elite soccer players, including their playing position. A ninety-nine male elite soccer players were compared to controls (n = 107) and tested for quadriceps and hamstrings isokinetic strength at speed 60°/s, 180°/s, and 300°/s, jump performance, and genotypes of ACTN3 (R577X, rs1815739), ACE (I/D, rs1799752), NOS3 (Glu298Asp, rs1799983), AMPD1 (34C/T, rs17602729), UCP2 (Ala55Val, rs660339), BDKRB2 (+9/-9, rs5810761) and IL1RN (VNTR 86-bp). The ACTN3 XX homozygotes in defenders had lower quadriceps and hamstring isokinetic strength in all tested speeds than ACTN3 RX and RR genotypes (p < 0.05) . The ACTN3 RR homozygotes in defenders had higher quadriceps strength in all tested velocities than the RX heterozygotes (p < 0.05). We also found other associations between playing-position in soccer and increased strength of lower limbs for AMPD1 CC and NOS3 Glu/Glu genotypes, and IL1RN*2 allele carriers. Total genetic score regression explained 26% of the variance in jump performance and isokinetic strength. The ACTN3 R allele, NOS3 Glu/Glu genotypes, and IL1RN*2 allele pre-disposed the attackers and defenders playing position in elite soccer, where those positions have higher strength and power measures than midfielders. Midfielders have lower strength and power conditions than other playing positions without relation to strength and power genes. [ABSTRACT FROM AUTHOR]

Heritability studies on sport-related traits accepted that endurance, speed, power, and strength abilities include an active genetic predisposition to elite soccer participation. This study evaluates the influence of selected genetic variants on performance in speed, power, and strength laboratory tests on a group of elite soccer players, including their playing position. A ninety-nine male elite soccer players were compared to controls (n = 107) and tested for quadriceps and hamstrings isokinetic strength at speed 60°/s, 180°/s, and 300°/s, jump performance, and genotypes of ACTN3 (R577X, rs1815739), ACE (I/D, rs1799752), NOS3 (Glu298Asp, rs1799983), AMPD1 (34C/T, rs17602729), UCP2 (Ala55Val, rs660339), BDKRB2 (+9/-9, rs5810761) and IL1RN (VNTR 86-bp). The ACTN3 XX homozygotes in defenders had lower quadriceps and hamstring isokinetic strength in all tested speeds than ACTN3 RX and RR genotypes (p < 0.05). The ACTN3 RR homozygotes in defenders had higher quadriceps strength in all tested velocities than the RX heterozygotes (p < 0.05). We also found other associations between playing-position in soccer and increased strength of lower limbs for AMPD1 CC and NOS3 Glu/Glu genotypes, and IL1RN*2 allele carriers. Total genetic score regression explained 26% of the variance in jump performance and isokinetic strength. The ACTN3 R allele, NOS3 Glu/Glu genotypes, and IL1RN*2 allele pre-disposed the attackers and defenders playing position in elite soccer, where those positions have higher strength and power measures than midfielders. Midfielders have lower strength and power conditions than other playing positions without relation to strength and power genes.

Galiano, C, Pareja-Blanco, F, Hidalgo de Mora, J, and Sáez de Villarreal, E. Low-velocity loss induces similar strength gains to moderate-velocity loss during resistance training. J Strength Cond Res 36(2): 340–345, 2022—This study aimed to analyze the effects of 2 velocity-based resistance training (VBT) programs that used the same relative loading but differed in the velocity loss (VL) throughout the set: 5% (VL5) vs. 20% (VL20). Twenty-eight physically active men (age: 23.0 ± 3.2 years; height: 175.8 ± 4.7 cm; body mass: 73.8 ± 10.8 kg) were randomly assigned to 2 groups: VL5 (n = 15) or VL20 (n = 13). Subjects followed a 7-week (14 sessions) VBT program using the squat exercise while repetition velocity was monitored. The following variables were assessed at pretest and posttest: estimated 1-repetition maximum (1RM); average velocity attained for all absolute loads common to pretest and posttest (AV); average velocity for those loads that were moved faster than 1 m·s−1 (AV > 1); average velocity for those loads that were moved slower than 1 m·s−1 (AV < 1); countermovement jump (CMJ); and 20-m running sprint time (T20). T20 and CMJ height were assessed before each training session to analyze their evolution during the training program. The VL5 group executed only 32.6% of the total repetitions performed by the VL20 group (156.9 ± 25.0 vs. 480.5 ± 162.0 rep). Both groups improved significantly (p < 0.01) in all variables analyzed (1RM, AV, AV > 1, AV < 1, CMJ, and T20) from pretest to posttest, with no significant differences between them. Therefore, a low VL (5%) induced similar gains in strength, jump, and sprint performance to a moderate VL of 20%, despite VL5 performing only 32.6% of the repetitions achieved by the VL20 group. [ABSTRACT FROM AUTHOR]

Although it is well known that both stretching and foam rolling can acutely increase the range of motion (ROM) and affect performance, the effects of a combined treatment (foam rolling and stretching) are not yet clear. Hence, the purpose of this meta-analysis was to compare the combined effect to that of stretching or foam rolling alone on both ROM and performance. We assessed the effect of a combined treatment on ROM and compared it to the effect of stretching, foam rolling, and a control condition by applying a random-effect meta-analysis. We also applied the same model to compare the effect of the combined treatment on performance. Moreover, by applying a mixed-effect model, we performed subgroup analyses with the stretching technique, type of foam rolling, tested muscles, type of task, and the order of the combined treatment. We found a significant overall effect on ROM change when comparing the combined treatment with the control condition (effect size (ES) = -0.332); however, no significant effect was found when comparing it to stretching (ES = 0.032) or foam rolling alone (ES = -0.225). The meta-analysis revealed no significant overall effect on performance when the combined treatment was compared to stretching alone (ES = - 0.029). However, the subgroup analysis for performance revealed a superior effect for the combined treatment compared to stretching alone, but only if foam rolling was followed by stretching (ES = -0.17), and not vice versa. Athletes do not have to combine stretching with foam rolling since no additional effect was observed. However, to increase performance, the combination of foam rolling followed by stretching can lead to greater improvements. [ABSTRACT FROM AUTHOR]

In an effort to evaluate the mechanisms underpinning performance in alpine ski racing, researchers have focused on the predictive validity of measures derived from fitness assessments. However, a limitation of this literature is the absence of practice time, since prolonged training may naturally develop specific fitness capacities, making some tests of physical ability less predictive of performance. We examine the relationship between fitness tests, practice, and performance using linear regressions with fitness test data, practice history data, and performance results from adolescent alpine ski racers attending professional development academies in the United States (N = 82). Only aerobic capacity (i.e. 20 m shuttle run) was significantly associated with more practice time. After controlling for practice hours, 5.5–6.5% of variance in ski performance was significantly explained by assessments of lower body power (i.e. standing long jump, triple jump), anaerobic capacity (i.e. 60 s box jump), and upper body strength/endurance (i.e. push-ups). Findings highlight the important role of anaerobic power on alpine ski racing performance, which may be developed outside of regular practice, possibly through weight training or physical maturation. The small variance explained by physical/physiological measures suggests that superior ski performance is likely a product of various skills and characteristics (e.g. technical, tactical, perceptual-cognitive, psychosocial). [ABSTRACT FROM AUTHOR]

The aim of this study was to verify the effects of different aerobic intensities combined with the same resistance training on strength and aerobic performances. Thirty-nine men were randomly assigned to a low-intensity group (LIG), moderate-intensity group (MIG), high-intensity group (HIG), and a control group. The training program consisted of full squat, jumps, sprints, and running at 80% (LIG), 90% (MIG), or 100% (HIG) of the maximal aerobic speed for 16-20 minutes. The training period lasted for 8 weeks, followed by 4 weeks of detraining. Evaluations included 20-m sprints (0-10 m: T10; 0-20 m: T20), shuttle run, countermovement jump (CMJ), and strength (1RMest) in full squat. There were significant improvements from pre-training to post-training in T10 (LIG: 4%; MIG: 5%; HIG: 2%), T20 (3%; 4%; 2%), CMJ (9%; 10%; 7%), 1RMest (13%; 7%; 8%), and oxygen uptake (...O2max; 10%; 11%; 10%). Comparing the changes between the experimental groups, 1RMest gains were significantly higher in the LIG than HIG (5%) or MIG (6%). Furthermore, there was a tendency for higher gains in LIG and MIG compared with HIG, with "possibly" or "likely" positive effects in T10, T20, and CMJ. Detraining resulted in performance decrements, but minimal losses were found for ...O2max in LIG (-1%). Concurrent training seems to be beneficial for strength and aerobic development regardless of the aerobic training intensity. However, choosing lower intensities can lead to increased strength and is recommended when the cardiorespiratory gains should be maintained for longer. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare physical performance in amateur handball players of 2 different competitive levels. Thirty-four senior handball players were divided into 2 groups according to their competitive level (regional category: REG or national category: NAC). Although no significant differences were found between groups in any of the horizontal jump (HJ) or vertical jump (VJ) variables (p> 0.05), NAC players obtained a better performance in the repeated sprint ability (RSA) test (RSABest [the best attempt] and RSATT [the total time in the total of sprints] in 15 m and 30 m), in change of direction ability (CODA) and in the Yo-Yo Intermittent Recovery Test Level 1 (YYIR1) test (p< 0.01, effect size = 21.32 to 1.75, large). A significant association was observed between the body mass index (BMI) and the HJ or VJ capacity (r = -0.35 to -0.55, p< 0.01), the RSA15mBest and RSA30mBest (r = 0.41 to 0.59, p< 0.01), and YYIR1 distance (r = -0.54, p≤ 0.05), and a also between the performance in the HJ or the VJ and the RSA15mBest and RSA30mBest, the CODA and the YYIR1, and between the RSA30m Best and the YYIR1 (r = -0.54, p ≤ 0.05). Specific strength and conditioning programs should aim toward improving RSA, CODA, and YYIR1, as these abilities may be needed at higher levels of competition. The programs also should aim toward improved HJ and VJ abilities, given their association with RSA, CODA, and YYIR1 performance. Moreover, maintaining an adequate BMI may aid players to sustain greater physical performance levels. [ABSTRACT FROM AUTHOR]

The pole vault is a complex track and field discipline requiring speed, strength, and efficient technique. Strength is a fundamental physical requirement, which facilitates general sprinting ability; this in turn represents the exploitable potential during the approach, where kinetic energy for the subsequent vault is generated. This study investigated the relationships between pole vault height, approach speed, sprint-speed potential, and indicators of both explosive and reactive strength in 20 international female pole vaulters. Furthermore, changes in step characteristics between flying sprints and approach runs were analyzed. Data were collected during and after an international pole vault competition. The correlations between approach speed and vault height, between sprint speed and approach speed, and between explosive strength indicators and sprint speed were large or very large. However, the correlation between reactive strength and sprint speed was small. Differences in speed during the vault approach compared with the flying sprint are mainly due to reduced step length rather than lower step frequency. With the help of a flow chart and regression equations, sound decisions can be made regarding the prioritization of various training components of pole vaulters. With this tool, coaches and athletes can easily evaluate whether or not a facilitator ability is sufficient for improving a more specific performance measure on the way to the central criterion: pole vault height. Furthermore, the results of this study suggest that maintaining step length should be emphasized during approach drills to best exploit sprint-speed potential during the pole vault approach. [ABSTRACT FROM AUTHOR]

This study investigated the effects on neuromuscular performance of a 6-week Optimal Load Training (OLT) and a novel modified Complex Training (MCT) (complex pairs: the same exercise using a moderate and an OL) in basketball players, in-season. Eighteen male athletes were randomly assigned to one of the protocols. Anthropometric measurements were taken to evaluate body composition. Lower- and upper-body maximum dynamic strength, countermovement jump (CMJ), standing long jump (SLJ), 10-m sprint and change of direction (COD) were also assessed. Moderate-to-large strength gains (presented as percentage change ± 90% confidence limits) were obtained for half-squat (OLT: 10.8 ± 5.3%; MCT: 17.2 ± 11.6%) and hip thrust (OLT: 23.5 ± 17.7%; MCT: 28.2 ± 19.0%). OLT athletes achieved likely small improvements in sprint (1.6 ± 1.6%) and COD (3.0 ± 3.2%). Players in the MCT attained likely moderate improvements in COD (3.0 ± 2.0%) and possibly small in SLJ (2.5 ± 4.6%). No protocol relevantly affected CMJ or body composition. An ANCOVA test revealed unclear between-group differences. In conclusion, both protocols increased basketball players' strength without the use of heavy loads (> 85% 1RM) and without impairing sprint, CMJ and SLJ performance. These findings suggest that basketball strength and conditioning professionals may use either method to counteract strength losses during the season. [ABSTRACT FROM AUTHOR]