Measures Of Athletic Performance Research Articles

Determination of locomotor qualities in elite Australian Football: A pragmatic approach

ABSTRACT The study examined the utility of surrogate measures of athletic performance to determine locomotor qualities (maximal aerobic velocity and peak velocity) in elite Australian Football (AF). 29 professional AF players undertook aerobic fitness (3km time-trial [TT] and 30–15 Intermittent Fitness Test [30–15 IFT]) and peak velocity (PV; 50 m maximal sprints using 10Hz GPS) assessments in pre-season. Characteristics of TT performance (mean velocity, 500m and 1km splits) were compared with a surrogate for maximal aerobic velocity (MAV; 80% of 30–15 IFT final velocity). PVs derived from sprint tests were compared to those attained in AF matches (10 Hz GPS). Higher Pearson correlations were observed between MAV versus the fastest 500m (r = 0.74) and 1km (r = 0.75) of the 3km TT, but they were not superior to mean velocity (r = 0.72; p ≥ 0.30) which also demonstrated the lowest bias (p ≤ 0.01) and equivalent typical errors (0.16–0.17 m.s−1). Peak velocity was higher across match observations (0.28, CI: ± 0.17 m.s −1, p = 0.017) versus sprint tests. There was no impact of playing position on the determination of locomotor qualities using surrogate measures of locomotor qualities. Locomotor qualities can be determined practically using 10Hz GPS devices during 3km time-trials and competitive matches (assuming appropriate signal quality), without additional fitness assessments.

Can Biomechanical Testing After Anterior Cruciate Ligament Reconstruction Identify Athletes at Risk for Subsequent ACL Injury to the Contralateral Uninjured Limb?

Background: Athletes are twice as likely to rupture the anterior cruciate ligament (ACL) on their healthy contralateral knee than the reconstructed graft after ACL reconstruction (ACLR). Although physical testing is commonly used after ACLR to assess injury risk to the operated knee, strength, jump, and change-of-direction performance and biomechanical measures have not been examined in those who go on to experience a contralateral ACL injury, to identify factors that may be associated with injury risk. Purpose: To prospectively examine differences in biomechanical and clinical performance measures in male athletes 9 months after ACLR between those who ruptured their previously uninjured contralateral ACL and those who did not at 2-year follow-up and to examine the ability of these differences to predict contralateral ACL injury. Study Design: Case-control study; Level of evidence, 3. Methods: A cohort of male athletes returning to level 1 sports after ACLR (N = 1045) underwent isokinetic strength testing and 3-dimensional biomechanical analysis of jump and change-of-direction tests 9 months after surgery. Participants were followed up at 2 years regarding return to play or at second ACL injury. Between-group differences were analyzed in patient-reported outcomes, performance measures, and 3-dimensional biomechanics for the contralateral limb and asymmetry. Logistic regression was applied to determine the ability of identified differences to predict contralateral ACL injury. Results: Of the cohort, 993 had follow-up at 2 years (95%), with 67 experiencing a contralateral ACL injury and 38 an ipsilateral injury. Male athletes who had a contralateral ACL injury had lower quadriceps strength and biomechanical differences on the contralateral limb during double- and single-leg drop jump tests as compared with those who did not experience an injury. Differences were related primarily to deficits in sagittal plane mechanics and plyometric ability on the contralateral side. These variables could explain group membership with fair to good ability (area under the curve, 0.74-0.80). Patient-reported outcomes, limb symmetry of clinical performance measures, and biomechanical measures in change-of-direction tasks did not differentiate those at risk for contralateral injury. Conclusion: This study highlights the importance of sagittal plane control during drop jump tasks and the limited utility of limb symmetry in performance and biomechanical measures when assessing future contralateral ACL injury risk in male athletes. Targeting the identified differences in quadriceps strength and plyometric ability during late-stage rehabilitation and testing may reduce ACL injury risk in healthy limbs in male athletes playing level 1 sports. Clinical Relevance: This study highlights the importance of assessing the contralateral limb after ACLR and identifies biomechanical differences, particularly in the sagittal plane in drop jump tasks, that may be associated with injury to this limb. These factors could be targeted during assessment and rehabilitation with additional quadriceps strengthening and plyometric exercises after ACLR to potentially reduce the high risk of injury to the previously healthy knee. Registration: NCT02771548 (ClinicalTrials.gov identifier).

Comparison of instability resistance training, traditional resistance training and plyometric training on athletic performance parameters.

The objective of the study was to compare traditional resistance, instability resistance, and plyometric training methods on measures of athletic performance in healthy subjects. Sixty five healthy, physically active male students were randomly assigned to the following groups: traditional resistance training (RT, n=22), instability training (IT, n=22), and plyometric training (PLY, n=21).Athletic performance parameters were assessed pre- and post-training using chair squat test, standing stork test, shuttle run test, t-test, and vertical jump test. General linear univariate model with baseline as covariate (ANCOVA) was used for analyzing the change in outcome from baseline to post-treatment. Statistically significant improvement was observed in all the athletic performance parameters in all three groups after sevenweeks of training (p-value<0.05). The highest change in chair squat test was reported for RT compared to IT (p-value<0.001) and PLY (p-value<0.001). The change in standing stork test among the IT group was substantially higher than that among RT (p-value=0.007) but did not significantly differ from that among the PLY (p-value=0.27). No statistically significant difference was observed in post-test values of vertical jump test among three groups. The highest change in t-test and shuttle run test was reported for PLY compared to IT (p-value<0.001) and RT (p-value<0.001). Based on the findings of this study, it is suggested that IT and PLY can be included with traditional RT to improve various aspects of athletic performance in healthy physically active individuals. The current study will give an insight to athletes, coaches, and trainers regarding utilization of appropriate training methods in enhancing athletic performance. However, further research is required to establish the effectiveness.

Relationship between energy availability, energy conservation and cognitive restraint with performance measures in male endurance athletes

BackgroundLow energy availability in male athletes has gained a lot of attention in recent years, but direct evidence of its effects on health and performance is lacking. The aim of this research was to objectively measure energy availability (EA) in healthy male endurance athletes without pre-existing relative energy deficiency signs during pre-race season.MethodsTwelve trained endurance athletes (performance level 3, 4, and 5) participated in the cross-sectional controlled laboratory study. Fat-free mass, exercise energy expenditure, and energy intake were measured to calculate EA. Resting energy expenditure was measured and estimated to assess energy conservation. Three specific performance tests were used to assess endurance, agility, and explosive strength performance. For psychological evaluation, the Three Factor Eating Questionnaire and a short Well-being questionnaire were completed.ResultsMean EA was 29.5 kcal/kg FFM/day. The majority (66.6%) had EA under the threshold for low EA in females. Critical cognitive restraint (≥13) was reported by 75% of participants. There were no differences in performance, blood values, or psychological evaluation when subjects were divided into two groups divided by EA = 30 kcal/kg FFM/day. Cognitive restraint was negatively associated with measured resting energy expenditure and energy conservation (r = −.578, p = .025 and r = −.549, p = .032, respectively).ConclusionsThe mean EA measured in this study supports the theory that the threshold for low EA in endurance male athletes might be under the threshold for females. In addition, we confirmed cognitive restraint could be useful for early detection of energy conservation. The high cognitive restraint as measured in our sample stressed the need of eating behavior screening in endurance athletes in order to reduce risk of any disordered eating patterns.

Optimizing Team Sport Training With Multi-Objective Evolutionary Computation

Abstract This research introduces a new novel method for mathematically optimizing team sport training models to enhance two measures of athletic performance using an evolutionary computation based approach. A common training load model, consisting of daily training load prescriptions, was optimized using an evolutionary multi-objective algorithm to produce improvements in the mean match-day running intensity across a competitive season. The optimized training model was then compared to real-world observed training and performance data to assess the potential improvements in performance that could be achieved. The results demonstrated that it is possible to increase and maintain a stable level of match-day running performance across a competitive season whilst adhering to model-based and real-world constraints, using an intelligently optimized training design compared a to standard human design, across multiple performance criteria (BF+0 = 5651, BF+0 = 11803). This work demonstrates the value of evolutionary algorithms to design and optimize team sport training models and provides support staff with an effective decision support system to plan and prescribe optimal strategies to enhance in-season athlete performance.

The relationship between isometric mid-thigh pull variables and athletic performance measures: empirical study of English professional soccer players and meta-analysis of extant literature.

There is currently limited evidence available to support the use of the isometric mid-thigh pull (IMTP) within professional soccer. The aim of this study was to analyze the association between IMTP variables, with common markers of athletic performance capability. Eleven professional development soccer players (age: 20±2 years, stature: 1.82±0.10 m, mass: 76.4±12.8 kg) performed IMTP, 5 m and 10 m accelerations, maximal sprint speed (MSS), countermovement jump (CMJ), and the 505 change of direction test (COD). Relative and absolute peak force (PF) and force at 50, 100, 150 and 200 ms values were measured during the IMTP. Relative F150, F200, PF displayed large to very large correlations with MSS (r=0.51, r=0.66, and r=0.76 respectively), while absolute PF also displayed a large correlation with MSS (r=0.57). Relative and absolute PF showed large correlations with CMJ height (r=0.54 and r=0.55 respectively). Relative F150 and F200 highlighted large correlations with COD ability (r=-0.68 and r=-0.60 respectively). Relative F200 and PF had a large negative correlation with 10 m acceleration (r=-0.55 and r=-0.53 respectively). This study provides an important contribution to knowledge within the area of IMTP testing in professional soccer by evidencing the prominence of the isometric force generating capacity as an underpinning factor in relation to athletic capability.

A Comparison of the Effects of a Six-Week Traditional Squat and Suspended Load Squat Program in Collegiate Baseball Players on Measures of Athletic Performance

Background: Acute studies suggest that resistance training with an unstable load suspended from the barbell increases core muscle activation with negligible detrimental effects on phasic muscle activation and force production compared to traditional barbell loading, but the effect of a suspended load program on athletic performance is unclear. Objective: The purpose of this study was to assess the effect of a six-week program where the back-squat was performed with a suspended load (SL) on vertical jump (VJ), change of direction ability (COD), single-leg balance, and one repetition maximum squat load (1RM). Methods: Thirty-two collegiate baseball players (20.4 ± 1.4 y, 86.0 ± 11.0 kg, 1.82 ± .065 m) were assigned to perform the back-squat with SL or traditional loading (CON). Additional exercises were done with traditional loading. Athletes completed VJ, T-tests to measure COD, star excursion balance test (SEBT) to measure single-leg balance, and 1RM PRE and POST program. A MANOVA was used to assess the dependent variables. Significance was set to p &lt; .05. Results: Effect of group × time (p = .152) and group (p = .095) were not significant, indicating CON and SL had similar performance. Effect of time (p &lt; .0001) was significant, suggesting POST performance improved relative to PRE. When groups were pooled, 1RM (p &lt; .0001) and T-test (p = .038) improved, but VJ (p = .255) and SEBT (p = .167) did not improve. Conclusion: Performing squats with SL does not appear to be detrimental to development during a six-week program.

The Relationship Between Functional Movement, Dynamic Stability, and Athletic Performance Assessments in Baseball and Softball Athletes.

Stapleton, DT, Boergers, RJ, Rodriguez, J, Green, G, Johnson, K, Williams, P, Leelum, N, Jackson, L, and Vallorosi, J. The relationship between functional movement, dynamic stability, and athletic performance assessments in baseball and softball athletes. J Strength Cond Res 35(12S): S42-S50, 2021-Despite recent popularity, the relationship between movement quality and measures of athletic performance remains inconclusive. This investigation sought to clarify the relationships between measures of movement quality and measures of athletic performance in baseball and softball athletes. Thirty-eight National Collegiate Athletic Association Division I baseball (n = 23; age 20.00 ± 1.38 years, lower-extremity [LE] limb length 93.91 ± 4.37, upper-extremity [UE] limb length 92.37 ± 4.48) and softball (n = 15; age 19.93 ± 1.28 years, LE limb length 89.43 ± 4.67, UE limb length 84.61 ± 4.39) athletes completed the Functional Movement Screen (FMS) and the Y Balance Test for the lower and upper extremities (YBTLQ and YBTUQ, respectively). Performance assessments were proagility (PA), vertical jump (VJ), and rotational medicine ball throw to the right and left (RMTR and RMTL, respectively). No significant correlations were seen between any of the composite scores of movement quality and athletic performance in baseball athletes; shoulder mobility was weakly correlated with PA (rs = 0.442, p = 0.035). Composite FMS was negatively correlated with RMTR (rs = -0.753) in softball athletes. In addition, in softball athletes, RMTR was negatively correlated with in-line lunge (rs = -0.544, p = 0.04), trunk stability push-up (rs = -0.761, p = 0.002), anterior YBTLQ reach (r = -0.628), and posterolateral YBTLQ reach (r = -0.683); VJ was correlated with posterolateral YBTLQ reach (r = 0.531) and superolateral (SL) YBTUQ reach (r = 0.591), and PA was negatively correlated with posterolateral YBTLQ (r = -0.60) and SL YBTUQ reach (r = -0.557). The differences in correlations of movement quality and athletic performance between baseball and softball athletes suggest movement quality influences performance differently in female athletes and male athletes.

Evaluations of effects of sleep surfaces on athletic performance in youth

We recently demonstrated that sleeping on high rebound [HR] mattress toppers induced a continuous and more rapid decline in core body temperature compared to low rebound [LR] mattress toppers during the initial phase of nocturnal sleep in young healthy volunteers. HR toppers are characterized by their supportive feel and high breathability whereas LR toppers are pressure-absorbing. In the current study, we evaluated effects of HR mattress toppers on objectively-(actigraphy) and subjectively-(questionnaires) evaluated sleep, vigilance (psychomotor vigilance test), and athletic performance (40-m sprint time, long jump distance, and star drill time) in youth male athletes age 10–19, in two sessions: fifty-one subjects in 2013 (study I) and 23 subjects in 2014 (study II). Sleeping on HR mattress toppers for four to six weeks improved some athletic performance measures compared to sleeping on LR or sleeping directly on spring mattresses without a topper. Statistically significant improvements in 40-m sprint time in study I (compared to LR) and in star drill time in study II (no topper) were observed. No changes in sleep and psychomotor vigilance were observed. These results suggest selecting optimal sleep surfaces may contribute to the maximization of athletic performances, and further studies are warranted.

The Effect of Overreaching on Neuromuscular Performance and Wellness Responses in Australian Rules Football Athletes.

Campbell, PG, Stewart, IB, Sirotic, AC, and Minett, GM. Title: The effect of overreaching on neuromuscular performance and wellness responses in Australian rules football athletes. J Strength Cond Res 34(6): 1530-1538, 2020-This study seeks to evaluate the effect of periodized fluctuations in training load on wellness and psychological questionnaires, perceived exertion, performance, and neuromuscular measures in team-sport athletes. Thirteen amateur Australian rules football athletes completed 6 weeks of periodized training, consisting of 2-week normal training (NT), intensified training (IT), and taper training (TT). Training sessions were quantified using global positioning system devices, heart-rate, and session rating of perceived exertion (sRPE), with wellness (general soreness, sleep quality/quantity, readiness to train, fatigue, stress, mood, and motivation) questionnaires collected daily. Psychological (Recovery-Stress Questionnaire for Athletes) and physical performance (countermovement jump, cycle ergometer peak power, 30-m sprint, and 2-km time trial) markers were measured after each training period. Perceived (sRPE) and mechanical loading were higher for IT than NT, and IT than TT (p < 0.03; d = 0.65-25.34). Cycle ergometer peak power, 30-m sprint, 2-km time trial, and countermovement jump height showed reductions in performance after IT compared to initial testing (p < 0.02; d = 0.51-1.46), with subsequent increases in performance after TT (p < 0.04; d = 0.66-2.27). Average wellness was higher during NT compared to IT (p = 0.005; d = 1.11). Readiness to train did not significantly differ from NT to IT or TT (p < 0.55; d = <0.59); however, readiness to train did improve during TT after the IT (p = 0.01; d = 1.05). The disturbances in performance, perceptual, and mood states may indicate a state of functional overreaching. The findings suggest that an averaged wellness score may be useful in potentially identifying overreaching. However, despite the popularity of wellness in monitoring systems, these measures overall demonstrated a limited capacity to differentiate between periodized fluctuations in load.

Maximum Aerobic Function: Clinical Relevance, Physiological Underpinnings, and Practical Application.

The earliest humans relied on large quantities of metabolic energy from the oxidation of fatty acids to develop larger brains and bodies, prevent and reduce disease risk, extend longevity, in addition to other benefits. This was enabled through the consumption of a high fat and low-carbohydrate diet (LCD). Increased fat oxidation also supported daily bouts of prolonged, low-intensity, aerobic-based physical activity. Over the past 40-plus years, a clinical program has been developed to help people manage their lifestyles to promote increased fat oxidation as a means to improve various aspects of health and fitness that include reducing excess body fat, preventing disease, and optimizing human performance. This program is referred to as maximum aerobic function, and includes the practical application of a personalized exercise heart rate (HR) formula of low-to-moderate intensity associated with maximal fat oxidation (MFO), and without the need for laboratory evaluations. The relationship between exercise training at this HR and associated laboratory measures of MFO, health outcomes and athletic performance must be verified scientifically.

Effects of Warming Up With Lower-Body Wearable Resistance on Physical Performance Measures in Soccer Players Over an 8-Week Training Cycle.

Bustos, A, Metral, G, Cronin, J, Uthoff, A, and Dolcetti, J. Effects of warming up with lower-body wearable resistance on physical performance measures in soccer players over an 8-week training cycle. J Strength Cond Res 34(5): 1220-1226, 2020-Warm-ups provide an opportune time to integrate specific movements to improve performance. This study aimed to examine the effects of adding wearable resistance (WR) lower-limb loading to a warm-up on physical performance measures in soccer athletes. Thirty-one national-level soccer players (aged 16-18 years) were matched for speed and allocated to either a WR training (WRT = 15) or an unloaded (CON = 16) group. Both groups performed the same warm-up 2-3x·wk for 8 weeks with the WRT group wearing 200- to 600-g loads on their calves. Pre-training, mid-training, and post-training data were collected for 10- and 20-m sprint times, repeated sprint ability, and vertical countermovement jump (CMJ) and horizontal countermovement jump (standing long jump [SLJ]) performance. Wearable resistance training improved pre-training to post-training 10- and 20-m sprint times more than the unloaded training (effect size [ES] = -1.06 to -0.96, respectively; 60.0-66.7 vs. 18.8-37.5% > smallest worthwhile change [SWC]). Both groups decreased CMJ over the first 4 weeks (ES ≥ 0.45) and increased CMJ performance over the second 4 weeks of training (ES ≥ 0.27). Both the WRT and CON groups improved SLJ performance after the 8-week training block (ES = 0.85 and 0.93, respectively; 86.7 and 62.5% > SWC, respectively), yet no differences were identified between groups. These findings indicate that 8 weeks (23 sessions) of WR training appears to elicit practically meaningful improvements in accelerated sprinting and horizontal jumping performance. Strength and conditioning practitioners should consider including WR in sports where sprinting and horizontal force production are critical performance indicators.

Strength, Jumping, and Change of Direction Speed Asymmetries Are Not Associated With Athletic Performance in Elite Academy Soccer Players.

The aims of the present study were 2-fold: (1) to measure interlimb asymmetries from a battery of fitness tests in youth soccer players and (2) to determine the association between asymmetry and measures of athletic performance. Sixteen elite youth soccer players (14.7 ± 0.2 years) performed a single-leg Abalakov test (ABK), change of direction (COD) test over 10 m (5 + 5) and 20 m (10 + 10), and an iso-inertial power test. Subjects also performed 10-, 20-, and 30-m sprints and a bilateral countermovement jump, which were correlated with all ABK, COD, and iso-inertial asymmetry scores. A one-way repeated-measures analysis of variance showed significant differences between interlimb asymmetry scores across multiple tests (p < 0.05), with the iso-inertial power test presenting the greatest magnitude of asymmetry, whereas individual data highlighted substantially greater interindividual differences in each test. Pearson r correlations showed no significant relationships (p > 0.05) between the different interlimb asymmetry scores, and between asymmetry scores and athletic performance. These findings show the test-specific nature of asymmetries in youth soccer players, with the iso-inertial power test being the most sensitive in detecting asymmetry. Moreover, the results obtained suggest that inherent asymmetry in young soccer players did not negatively impact their performance.

A systematic review and meta-analysis of the effects of foam rolling on range of motion, recovery and markers of athletic performance

ObjectiveTo conduct a systematic review with meta-analysis assessing the effects of foam rolling on range of motion, laboratory- and field-based athletic measures, and on recovery. Data sourcesMEDLINE, PubMed, EMBASE, SPORTDiscus and Science Direct were searched (2005–June 2018). Study selectionExperimental and observational studies were included if they examined the effects of foam rolling on measures of athletic performance in field or laboratory settings. Data extractionTwo investigators independently assessed methodologic quality using the Physiotherapy Evidence Database (PEDro) Scale. Study characteristics including participant age, sex and physical activity status, foam rolling protocol and pre- and post-intervention mean outcome measures were extracted. Data synthesisA total of 32 studies (mean PEDro = 5.56) were included in the qualitative analysis, which was themed by range of motion, laboratory-based measures, field-based measures and recovery. Thirteen range of motion studies providing 18 datasets were included in the meta-analysis. A large effect (d = 0.76, 95% CI 0.55–0.98) was observed, with foam rolling increasing range of motion in all studies in the analysis. ConclusionsFoam rolling increases range of motion, appears to be useful for recovery from exercise induced muscle damage, and there appear to be no detrimental effect of foam rolling on other athletic performance measures. However, except range of motion, it cannot be concluded that foam rolling is directly beneficial to athletic performance. Foam rolling does not appear to cause harm and seems to elicit equivalent effects in males and females.

Isometric Midthigh Pull Performance Is Associated With Athletic Performance and Sprinting Kinetics in Division I Men and Women's Basketball Players.

Townsend, JR, Bender, D, Vantrease, WC, Hudy, J, Huet, K, Williamson, C, Bechke, E, Serafini, PR, and Mangine, GT. Isometric midthigh pull performance is associated with athletic performance and sprinting kinetics in Division I men and women's basketball players. J Strength Cond Res 33(10): 2665-2673, 2019- The relationships between isometric mid-thigh pull (IMTP) force, athletic performance measures, and sprint kinetics in Division I men's and women's basketball players were investigated. Twenty-three (male = 8, female = 15) Division 1 basketball players completed a maximal 20-m sprint trial while tethered to a device that provided kinetic feedback (peak and average sprinting power, velocity and force). Additionally, 1 repetition maximum (1RM) front squat, 1RM hang clean, vertical jump height, and agility (proagility and lane agility) tests were performed. Rate of force development (RFD) at 50, 100, 150, 200 and 250 milliseconds of IMTP and peak force (PF) were also collected. Pearson's product-moment correlation analysis was used to examine the relationships between these measures. Significant (p ≤ 0.05) relationships were observed between IMTP PF and sprint time over all distances (5-20 m; r = -0.62 to 0.69), average sprint velocity (r = 0.50-0.70), peak sprint velocity (r = 0.50-0.54), average sprint force (r = 0.48-0.69), and average sprint power (r = 0.62-0.73). Sprinting kinetic measures (average force and power) over the first 5 m were also significantly (p ≤ 0.05) related to IMTP RFD (50-250 ms; r = 0.42-0.62). Results indicate that IMTP variables are significantly associated with 20-m sprint kinetics. Specifically, IMTP RFD appears to be related to the initial acceleration kinetics of a sprint. Strength and conditioning professionals can possibly implement the IMTP for improved assessment and monitoring of athletic performance and training.

The Relationship Between Asymmetry and Athletic Performance: A Critical Review.

Maloney, SJ. The relationship between asymmetry and athletic performance: A critical review. J Strength Cond Res 33(9): 2579-2593, 2019-Symmetry may be defined as the quality to demonstrate an exact correspondence of size, shape, and form when split along a given axis. Although it has been widely asserted that the bilateral asymmetries are detrimental to athletic performance, research does not wholly support such an association. Moreover, the research rarely seeks to distinguish between different types of bilateral asymmetry. Fluctuating asymmetries describe bilateral differences in anthropometric attributes, such as nostril width and ear size, and are thought to represent the developmental stability of an organism. There is evidence to suggest that fluctuating asymmetries may be related to impaired athletic performance, although contradictory findings have been reported. Sporting asymmetries is a term that may better describe bilateral differences in parameters, such as force output or jump height. These asymmetries are likely to be a function of limb dominance and magnified by long-standing participation within sport. Sporting asymmetries do not seem to carry a clear influence on athletic performance measures. Given the vast discrepancy in the methodologies used by different investigations, further research is warranted. Recent investigations have demonstrated that training interventions can reduce sporting asymmetries and improve performance. However, studies have not sought to determine whether the influence of sporting asymmetry is independent of improvements in neuromuscular parameters. It may be hypothesized that the deficient (weaker) limb has a greater potential for adaptation in comparison to the strong limb and may demonstrate greater responsiveness to training.

Arthroscopic correction of femoroacetabular impingement improves athletic performance in male athletes.

To measure the changes in athletic performance in athletes treated arthroscopically for femoroacetabular impingement and compare results to a matched controlled athletic cohort, over a 1-year period. Male athletes scheduled for arthroscopic correction of symptomatic FAI were recruited and tested (pre-operatively and 1-year postsurgery) for measures of athletic performance which included acceleration (10-m sprint), change of direction speed (CODS), squatting depth, and reactive strength index (RSI). The FAI group was compared to a matched, healthy, control group who were tested at baseline and 1year later with no disruption to their regular training or competition status; the prevalence of anterior groin pain during testing in either group was recorded. Hip range of motion (ROM) was also measured for both groups at baseline and at 1year in the FAI group to look for change following intervention. Prior to surgery, the FAI group were slower than the control group (p < 0.001) for acceleration (3% slower) and CODS (10% slower). At 1 year, 91% of the FAI group returned to full competition at an average time of 17weeks, while substantial reductions in pain were also noted during acceleration (51-6%, p = 0.004), CODS (62-8%, p = 0.001), and squat test (38-8%, p = 0.003). Significant improvements were seen in the FAI group for CODS (7%, p < 0.001) and squat depth measures (6%, p = 0.004) from baseline to 1 year (significant time × group interaction effects were noted for these also). The changes in performance in the control group over time were non-significant across all of the measures (n.s.). At 1-year postsurgery, there were no statistically significant differences between the groups for any of the athletic measures. There was a significant and clinically important improvement in range of hip motion in the FAI group at 1-year postsurgery (p < 0.05). Symptomatic FAI causes substantial reductions in athletic performance compared to healthy competitors placing these athletes at a distinct performance disadvantage. The results from the current study demonstrate that arthroscopic correction (including labral repair) in athletes with symptomatic FAI, reduces pain and restores athletic performance to a level which is comparable to healthy athletes, at 1year. II.

Effects of Contrast Strength vs. Plyometric Training on Lower-Limb Explosive Performance, Ability to Change Direction and Neuromuscular Adaptation in Soccer Players.

Hammami, M, Gaamouri, N, Shephard, RJ, and Chelly, MS. Effects of contrast strength vs. plyometric training on lower-limb explosive performance, ability to change direction and neuromuscular adaptation in soccer players. J Strength Cond Res 33(8): 2094-2103, 2019-The aim was to compare the effects of 2 differing 8-week in-season strength training programs (contrast strength training [CST] vs. plyometric training [PT]) on selected performance tests (5 and 40 m sprints, S 4 × 5 m change of direction test, squat jump [SJ] and countermovement jump [CMJ], leg peak power on a cycle-ergometer force-velocity test, 1 repetition maximal half-squat, and electromyographic [EMG] activity of the vastus lateralis, vastus medialis, and rectus femoris muscles during vertical jump tests). Forty male soccer players (age = 15.8 ± 0.4 years; body mass = 58.8 ± 6.3 kg; body height = 1.74 ± 0.06 m; body fat = 10.5 ± 1.9%) were divided between a contrast strength group (CSG, n = 14), plyometric group (PG, n = 14), and control group (CG, n = 12). Both training programs enhanced sprint performance (p < 0.001 in 5 m; p ≤ 0.05 in 40 m) and change of direction test scores (p < 0.001) relative to controls. The plyometric group and CSG increased SJ height relative to the CG, with a slightly greater response in CSG compared with PG (p ≤ 0.05). Most CMJ scores increased significantly in both CSG and PG relative to the CG, with no intergroup differences in training response. Most force-velocity scores increased significantly in the CSG relative to PG and CG. The EMG parameters also increased in the CSG relative to both PG and CG. In summary, most measures of athletic performance in male soccer players were enhanced after CST and PT. However, the improvement of physical performance was better with 8 weeks of CST than with PT. Thus, coaches should be encouraged to include CST as an element of in-season conditioning.

Comparison of a Combined Strength and Handball-Specific Training vs. Isolated Strength Training in Handball Players Studying Physical Education.

The purpose of this study was to compare the effect of combined resistance training including handball-specific drill (CRT) with resistance training excluding handball-specific drill training (NSDT). Twenty-two male handball players who studied physical education were randomly assigned to two groups: CRT (combined resistance training with sport-specific drill; n = 12) and NSDT (resistance training without any sport-specific drill training; n = 10). Over a 10-week period during the competitive season, the players performed a specific training program twice per week, which replaced their normal team handball training. The CRT regimen consisted of a combined (associated) resistance training and handball-specific drill, whereas the NSDT program consisted of a resistance training without handball-specific drill (dissociated). Pre- and post-test measures included squat jump and countermovement jumps, bench press, back half squats, throwing velocity during a 3-step jump throw, and a jump shot, repeated-sprint ability (six 2 × 15-m shuttle sprints) (RSA), medicine ball throw and anthropometric measurements. In both groups, significant intervention effects (d ≥ 1.0) were seen for all sprint (3/3), throwing (3/3) and jump (2/2) measures. Regarding maximal strength parameters, an effect size lower than 0.5 was only detected in the NSDT group for half back squats (d = 0.48). The largest effects were observed in the NSDT group for squat jump (d = 6.20) and medicine ball throw (d = 6.07). Interaction effects (group × time) were found for 50 % (5/10) of parameters. The greatest difference between groups regarding performance development over time was detected for jump shot (interaction effect: η² = 0.748). In contrast, there was no difference in performance development in both groups over time for RSAbest (interaction effect: η² = 0.025). The current findings suggest that during the competitive season, 10 weeks of CRT with only two training sessions per week improved numerous measures of athletic performance in handball students of physical education. Such conditioning should be highly recommended as part of the annual training program of handball players.

Tendon and muscle fascicle length changes during running with compliant and stiff footwear cushioning

Footwear cushioning can have a direct influence on the rate of oxygen consumption (Worobets, Wannop, Tomaras, & Stefanyshyn, 2014), which is an accepted measure of athletic performance (Cavanagh & ...