Worthwhile Changes Research Articles

Seasonal Comparison of Pre-Adolescent Soccer Players' Physical Performance Using an Objective Physical Test Battery.

Soccer is a multifactorial sport, requiring physical, psychological, technical, and tactical skills to succeed. Monitoring and comparing physical characteristics over time is essential to assess players' development, customize training, and prevent injury. The use of wearable sensors is essential to provide accurate and objective physical data. In this longitudinal study, 128 male adolescent soccer players (from Under 12 to Under 19) were evaluated at two time points (pre- and post-season). Participants completed the Euleria Lab test battery, including stability, countermovement and consecutive jumps, agility, and quick feet tests. A single Inertial Measurement Unit sensor provided quantitative data on fifteen performance metrics. Percentage changes were compared to the Smallest Worthwhile Changes to assess significant changes over time. The results showed significant improvements in most variables, including a 19.7% increase in quick feet, 10.9% in stability, and 9.6% in countermovement jumps. In principal component analysis, we identified four principal components-strength-power, balance, speed-agility, and stiffness-that explained over 80% of the variance. These findings align with previous studies assessing seasonal changes in adolescent soccer players, showing that the proposed test battery seems to be adequate to highlight physical performance changes and provide coaches with meaningful data to customize training and reduce injury rates.

Reliability of a kinetic and kinematic assessment procedure for kicks in combat sports

ABSTRACT Ensuring reliability of measurement instruments in combat sports is crucial for coaches and researchers, promoting their widespread use. This study assessed the reliability of a procedure that measures kinetic and kinematic variables in karate athletes’ roundhouse kicks. Twenty-four male karate athletes participated, performing three kicks initially and three 48 h later. Paired Student’s t-test found no significant differences between tests. Bland–Altman plot revealed few outliers. Strong agreement between test and retest was shown by Pearson correlations, Intraclass Correlation Coefficient (ICC), and Coefficient of Variation (CV) for impact force variables: r = 0.96; ICC = 0.93; CV = 0.12%, impulse: r = 0.95; ICC = 0.93; CV = 1.08%, attack time: r = 0.82; ICC = 0.70; CV = 0.14%, contact time: r = 0.72; ICC = 0.60; CV = 0.18%, return time: r = 0.80; ICC = 0.71; CV = 4.28%, and kick time: r = 0.84; ICC = 0.77; CV = 2.88%. No Smallest Worthwhile Changes (SWC) were observed, and Cronbach’s alpha indicated acceptable internal consistency. In conclusion, the procedure demonstrated reliability in terms of internal and measurement consistency, without random errors.

Safety and Effectiveness of a Novel Color Corrector Serum for Causing Temporary Changes to Tooth Shade: A Randomized Controlled Clinical Study.

Tooth color is a major driver of facial esthetics. While permanent changes in tooth shade can be achieved by bleaching and restorations, there is a need for cosmetic products that can cause reversible color changes. This randomized controlled clinical study assessed the effectiveness and safety of a novel color-correcting product (Hismile™ V34 Color Corrector Serum™) versus a placebo (vehicle control lacking the color-change dyes). A single-center, randomized, controlled, examiner-blind, two-group, parallel design, single-use study design was followed. The test products were applied on a cotton bud for 30 s, and then, rinsed off. Tooth shade for maxillary central incisors was measured at baseline, immediately, and at 30 and 60 min, using the Vita Bleachedguide 3D-Master® Shade Guide and the EasyShade Advanced 4.0 spectrophotometer (for determining values of L*a*b*). The subjects (N = 60) had a baseline shade of 1M2 (rank 9) or darker. A single application of the test product resulted in an immediate and significant (p < 0.001) three shade improvement (26.2%) according to the shade guide, and the same significant benefits extended to 30 and 60 min. The placebo product did not alter tooth shade (p = 0.326). These changes were accompanied by significant improvements in the L value (whiteness) up to 30 min, and a reduction in b* (yellowness) for up to 60 min. Two-thirds of subjects using the test product stated in a survey that their teeth appeared both whiter and brighter. No safety issues arose from the use of the test product or vehicle control. These results indicate that using a color corrector can achieve worthwhile changes to tooth shade for up to 60 min.

Test-retest reliability and sensitivity of senior elite amateur boxers maximal punch force, as quantified by a vertically mounted force plate.

An ecologically valid, reliable and sensitive method of quantifying punch force variables would be useful for coaches and practitioners monitoring combat-specific performance. The present study utilised a vertically mounted force plate to quantify the peak punch force and rate of force development (RFD) of amateur boxers. Ten male senior elite amateur boxers performed maximal jab, cross, and hook punches across two separate days. The force plate showed excellent within-day and good-to-excellent between-day reliability for peak punch impact force and RFD (ICC 0.89-0.99). The CV% for all punch force variables were similar on day 1 (3-9%) and day 2 (4-10%). Standard error of measurement (SEM) and smallest worthwhile changes (SWC) revealed the force plate can detect small-to-moderate changes in punch performance. The greatest impact forces and RFD were found in the rear hook (2624 ± 581 N, 296448 ± 101823 N.s-1), followed by the lead hook (2524 ± 532 N, 256813 ± 81735 N.s-1), cross 2425 ± 545 N, 193004 ± 62671 N.s-1) and jab (1645 ± 537 N, 116675 ± 41577 N.s-1). The vertically mounted force plate is a reliable and sensitive test of punch performance, thus may be useful in determining the efficacy of training interventions.

Physical activity and exercise capacity as composite versus single categorical endpoints for trials of exercise-based cardiac rehabilitation interventions: comparison of sample size requirements

Abstract Funding Acknowledgements Type of funding sources: None. Introduction A composite primary endpoint consists of two or more component endpoints, events or outcomes. If any one of these is observed, it is considered that the composite primary endpoint has been reached. A potential advantage of a composite over a single primary endpoint in a randomised controlled trial (RCT) is a reduction of the required sample size. Purpose The combined endpoint "major adverse cardiac events" (MACE) is well-established in cardiovascular research, but MACE is often unsuitable in trials of exercise-based cardiac rehabilitation interventions with short follow-up periods. We therefore explored the application of a composite primary endpoint incorporating exercise capacity and physical activity for parallel-group RCTs of exercise-based cardiac rehabilitation (CR) interventions. Methods Our composite endpoint combines two categorical (binary) single endpoints, i.e., exercise capacity (given as maximum mechanical power output of a graded exercise test) and physical activity. Thresholds for categorisation were defined on literature-based minimal clinically worthwhile changes and defined as an increase of 15 W or more for improving exercise capacity and an increase of 10 min/day or more for improving moderate to vigorous physical activity (MVPA). If the aim of an intervention is to avoid clinically meaningful deterioration (i.e., to achieve maintenance as opposed to improvement), the threshold is defined as deterioration in exercise capacity of less than 15 W and a reduction in MVPA of less than 10 min/day (figure 1). To illustrate the impact of a single versus a composite primary end point on sample size requirements, we used real-world data from two completed phase 3 CR trials ([1] and [2]). We applied the commonly used formula for estimating sample sizes to detect the difference between the probabilities of an event in two independent groups [3]. Results Sample size requirements for detecting a between-group difference of 5%, 10%, 15% and 20% under the different endpoint approaches are shown in table 1. If the aim of the intervention is to achieve improvement, the composite endpoint results in approximately equivalent sample size requirements to the single endpoint. If the aim of the intervention is to achieve maintenance, the composite endpoint results in markedly lower sample size requirements compared to the primary endpoint. Statistically, these differences are driven by the percentage of improvers or maintainers in the control group of the reference population. Conclusion The composite primary endpoint approach can be a useful alternative to the single primary endpoint in trials of exercise-based CR. Depending on the baseline probability, it may be possible to reduce the sample size requirement by applying a composite endpoint. In our examples, the composite endpoint results in smaller sample size requirements when the intervention aim is to avoid clinically meaningful deterioration.

A study on the benefits of participation in an electronic tracking physical activity program and motivational interviewing during a three-month period

Background: The purpose was to investigate if participation in a three-month electronic tracking outdoor physical activity and a motivational interviewing (MI) intervention led to positive behavioural, psychological, and physiological outcomes. Methods: Based on a two-group pre-post design, 12 middle-aged women and 6 men were randomly assign to an experimental and a control group. Physical activity data were collected by wrist-worn activity sensors, and pre-post data were collected on the GHQ-12, the BREQ-2, body mass, body fat mass and total body muscle. Measures of cardiovascular fitness were taken pre to post. The experimental group was supported through individual MI coaching sessions and resistance-training for use in an outdoor gym. Magnitude based inferences (MBI) were calculated based on the disposition of the confidence limits for the mean differences to the smallest worthwhile changes. Results: The experimental group had a beneficial increase in its physical activity behaviour (steps). The control group had a medium decrease in identified regulation, the experimental group maintained the same level at the post-measure. Conclusion: Few studies have investigated how the combination of MI and the use of activity-tracking devices effect physical and mental health. This study investigates the use of both MI and activity-tracking devices on psychological well-being, motivation, and physical health in an outdoor context. Future research recommendations are given.

Shortcomings in the Operation and Coordination of Witness Protection in Australia. Where to from Here?

Witness protection in Australia has, to date, been less than successful in implementation and execution. An ad hoc system of Commonwealth and state/territory witness protection programs have co-existed with often substandard outcomes for participants, law enforcement and the criminal justice system. Although in accordance with Australia’s federal system of government, the framework of witness protection that has emerged has resulted in numerous witness protection programs in operation across states and territories with little in the way of consistency, cooperation and coordination. Reform in Australia’s witness protection system is needed to improve and streamline programs for the benefit of witnesses, communities and the criminal justice system. This article addresses shortcomings and draws attention to worthwhile changes that would benefit and enhance domestic witness protection.

Measurement properties of external training load variables during standardised games in soccer: Implications for training and monitoring strategies.

The aim of this study was to assess the measurement properties of external training load measures across three formats of standardised training games. Eighty-eight players from two English professional soccer clubs participated in the study spanning three consecutive seasons. External training load data was collected from three types of standardised game format drills (11v11, 10v10, 7v7+6) using Global Positioning Systems. For each external training load metric in each game format, the following measurement properties were calculated; coefficient of variation (CV%) to determine between- and within-subject reliability, intraclass coefficient correlation (ICC) to determine test-retest reliability, and signal-to-noise ratio (SNR) to determine sensitivity. Total distance (TD) and PlayerLoad™ (PL) demonstrated good sensitivity (TD SNR = 1.6–4.6; PL SNR = 1.2–4.3) on a group level. However, a wide variety of within-subject reliability was demonstrated for these variables (TD CV% = 1.7–36.3%; PL CV% = 4.3–39.5%) and corresponding intensity measures calculated per minute. The percentage contribution of individual planes to PL showed the lowest between-subject CV% (CV% = 2–7%), although sensitivity varied across formats (SNR = 0.3–1.4). High speed running demonstrated poor reliability across all three formats of SSG (CV% = 51–103%, ICC = 0.03–0.53). Given the measurement properties of external training load measures observed in this study, specifically the within-subject variation, reliability across trials of standardised training games should be calculated on an individual level. This will allow practitioners to detect worthwhile changes across trials of standardised game format drills. Such information is important for the appropriate implementation of training and monitoring strategies in soccer.

Learning from the experience and effectiveness of retirement village and extra care housing responses to the COVID-19 pandemic

Purpose This paper aims to describe the RE-COV study and to summarise its findings. It focuses particularly on the implications of lessons learned for national, operational and building design policy and practice. Design/methodology/approach Invitations to take part in a RE-COV study survey were emailed to the operators of 270 retirement villages and older people’s extra care housing schemes in England which were known to the Elderly Accommodation Counsel. Completed questionnaires were returned from 38 operators, online or electronically, between December 2020 and February 2021. Findings Survey findings evidenced the breadth and depth of the operators’ responses, the effects these had on residents’ lives and worthwhile changes which could be made. Outcomes demonstrated included higher levels of protection for residents from the COVID-19 virus compared to older people living in the general community, and high levels of residents feeling safe, supported and reassured. Practical implications The findings are used to offer evidence-based recommendations for housing operators, building designers and policymakers which could enhance resident, staff and operators’ health and well-being, both going forward and during possible future pandemics. Social implications There is evidence that retirement villages and extra care housing provided safe, resilient and supportive environments during the first year of the pandemic which were highly valued by residents. Originality/value This study addressed a knowledge gap regarding how the COVID-19 pandemic had impacted housing-with-care stakeholders, evidencing specifically how operators had responded, and what their response achieved.

Validity and reliability of Polar Team Pro GPS units for assessing maximum sprint speed in soccer players

Previous research has reported inconsistencies in the validity and reliability of different brands of global positioning systems (GPS). Therefore, it should be questioned whether GPS units measure the maximum speed measurements validly and reliably. The current study aimed to analyze the validity and reliability of Polar Team Pro GPS units (10 Hz) when used to measure maximum sprint speed. Sixteen amateur soccer players (age: 27.22 ± 4.70 years; height: 177 ± 6.05 cm; body mass: 73.66 ± 5.63 kg) were tested in the 40 m sprint. Two Polar Team Pro GPS units were positioned on each player, while the radar was placed on a 1 m high tripod placed 10 m behind the starting point. The data obtained from the Polar Team Pro GPS units were compared to determine inter-unit reliability. The data obtained from one of the Polar Team Pro GPS units and radar gun (gold standard) were compared to determine validity. Good inter-unit reliability between the Polar Team Pro GPS units was reported for maximum sprint speed, with low coefficients of variation (5%–6%) and low smallest worthwhile changes (0.4 for all systems). Regarding validity, the coefficient of correlation was extremely high for maximum sprint speed ( r = 0.938, p &lt; 0.001). Moreover, measurement differences between both systems were statistically insignificant (Mean Bias error = 0.144, R2 = 0.879, MAPE = 1.6%, MAE = 0.688, and RMSE = 0.697). Consequently, good reliability and perfect validity were observed, indicating that the Polar Team Pro GPS unit is suitable for maximum sprint speed measurements.

The Deceleration Deficit: A Novel Field-Based Method to Quantify Deceleration During Change of Direction Performance.

Clarke, R, Read, PJ, De Ste Croix, MBA, and Hughes, JD. The deceleration deficit: a novel field-based method to quantify deceleration during change of direction performance. J Strength Cond Res 36(9): 2434-2439, 2022-The study investigated the relationship between linear and change of direction (COD) speed performance components and the individual differences between deceleration deficit (DD) and COD deficit (CODD). Thirty-six subjects (mean ± SD : age = 20.3 ± 2.9 years; stature = 175.2 ± 7.7 cm; and body mass = 78.0 ± 16.7 kg) completed 3 trials of a 505 test in both turning directions (dominant [D]; nondominant [ND]) and 3 15-m linear sprints. Deceleration deficit was calculated by the 15-m approach in the 505 test, minus the athlete's linear 15-m sprint time. To compare individuals CODD and DD, z-scores were calculated, and moderate worthwhile changes (MWCs) were identified between these deficit z-scores. Significant correlations were identified between linear sprints and 505 time (D: r = 0.71, 0.74; P < 0.01. ND: r = 0.76, 0.75; P < 0.01) for 10-m and 15-m sprint. respectively, and between 505 performance and CODD (D: r = 0.74; P < 0.01. ND: r = 0.77; P < 0.01) and DD (D: r = 0.41, P < 0.05. ND: r = 0.44, P < 0.01). Deceleration deficit was significantly related to CODD (D: r = 0.59; P < 0.01. ND: r = 0.62; P < 0.01); however, 78% of subjects demonstrated differences between these deficit measures greater than an MWC. In conclusion, linear speed has the strongest significant relationship with 505 performance. Deceleration deficit could provide a more isolated construct than CODD which may be related to an athlete's deceleration capabilities.

Effectiveness of Upper Body Compression Garments Under Competitive Conditions: A Randomised Crossover Study withEliteCanoeists with an Additional Case Study

This study aimed to investigate the effects of upper body compression garments on performance changes in elite canoeists. A total of 23 elite athletes from the German Canoe Federation (6 women and 17 men) were recruited. On a regatta lake, the athletes completed a 1650-m test track with their competition or training boats and paddles. The athletes were randomised into two groups and performed the test track with and without upper body compression garments. Besides split and end times, capillary blood lactate concentrations were assessed. For statistical analysis, an effect-based approach ("Magnitude-Based Inferences") and an additional case study were conducted. For this purpose, the mean and individual effects were examined in relation to the smallest worthwhile changes. On average, the effect-based approach shows that upper body compression garments do not lead to clear changes in performance. The changes in lactate concentrations were clear, but were considered trivial. In contrast to the average statistical analysis, the results of the case study demonstrate that upper body compression garments lead to an improved performance in 13.0 % and a worsened performance in 4.4 % of athletes. Additionally, a decreased lactate concentration was found in 4.4 % and an increased lactate concentration in 17.4 % of athletes. Our study shows that, on average, upper body compression garments have no effects on the performance and lactate concentration of highly trained elite canoeists. In individual cases, however, there are beneficial as well as harmful effects that may have practical relevant consequences for elite athletes.

Effects of playing strategies on match activities and physiological responses in well-trained female tennis players derived by an alternative statistical approach

Summary Background This study aimed to investigate the effects of playing strategies on match activities and physiological responses in well-trained female tennis players. Materials and Methods Twelve well-trained female players (25 ± 5 years) played points against an opponent of similar ability. Thereby, the players were instructed to apply either a passive, an active, or their own playing strategy. The latter consisted of free play and served as a control condition. During play, the stroking activities, activity profile, and running activities were investigated by video camera and global positioning system measures. Additionally, the physiological responses were examined through heart rate, capillary blood lactate, and visual analog scale procedures. The effects of the playing strategies were described as factors of the smallest worthwhile changes. Results The passive and active playing strategies had contrary effects on the match activities and physiological responses. The effects were more likely on the stroking activities and activity profile than on running activities and physiological responses. Conclusions Our study shows that playing strategies have an impact on match activities and physiological responses in well-trained female tennis players. This should be considered, when planning training drills for the players or analyzing match play data.

Changes in the Incidence of Underweight and Overweight in Children and Adolescents from Rural Areas

Research background and hypothesis. Considering the socio-economic transformations affecting the life style of rural families of Estern Poland, it seemed worthwhile determining changes in the frequency of occurrence of overweight and underweight among girls and boys from this region, as the negative effects of improvements in life conditions include an increase in overweight and obesity, which in some countries takes the form of epidemics.Research aim was determine changes over time in the frequency of occurrence of underweight and overweight (including obesity) among children and adolescents in Eastern Poland considering social variation.Research methods. Information was obtained applying a questionnaire survey concerning the educational level of parents and the number of children in the family. The standards recommended by the International Obesity Task Force were used for the evaluation of underweight and overweight including obesity, based on the BMI index.Research results. During the period of time between 1998 and 2007, an increase was observed in the frequency of occurrence of overweight and obesity, accompanied by a decrease in underweight among boys. In girls, an opposite trend was noted – an increase in the number of underweight girls and a decrease in the frequency of occurrence of overweight and obesity. In addition, social differences were noted concerning BMI values: girls and boys with overweight and obesity most often came from families with lower levels of parental education and a larger number of children in the family.Conclusions and perspectives. The education of parents and the number of children, in spite of observed social and economic positive changes in Poland, still have an infl uence on the frequency of occurrence of overweight and obesity in children and the youth of the rural areas.Keywords: body mass index, time changes, social conditions.

Between-Game Variation of Physical Soccer Performance Measures in Highly Trained Youth Soccer Players.

Doncaster, G and Unnithan, V. Between-game variation of physical soccer performance measures in highly trained youth soccer players. J Strength Cond Res 33(7): 1912-1920, 2019-To assess the between-game variation in measures of physical performance during 11 vs. 11 soccer match play, over a short period, in highly trained youth soccer players. A single-cohort, observational, study design was used. Physical match performance data were collected from 17, male, highly trained, youth soccer players (age, 13.3 ± 0.4 years) over 3, 2 × 20 minutes, 11 vs. 11 matches. Using 10-Hz global positioning systems, the variables selected for analyses were total distance (TD), high-speed running (HSR), very high-speed running (VHSR), number of high-speed running efforts (HSReff), and number of very high-speed running efforts (VHSReff). Match data were also separated into cumulative 5-minute epochs, to identify the peak 5-minute epoch and the mean of the cumulative 5-minute epochs for each match. Variability was quantified using the coefficient of variation (CV), standard error of measurement, and intraclass correlation coefficient. Between- and within-player smallest worthwhile changes (SWC) were also calculated for each variable to aid in the interpretation of the data. Analysis of the variance between games reported a low CV for TD (3.8%) but larger CVs for HSR (33.3%), HSReff (35.4%), and VHSR and VHSReff (59.6 and 57.4%, respectively). Analysis of 5-minute epochs (peak and average) found an increase in the CVs beyond that of the values reported for the whole match. Between-player SWC in high-intensity physical performance data ranged from 24.7 to 42.4%, whereas within-player SWC ranged from 1.2 to 79.9%. The between-game variability of high-intensity and very high-intensity activities in youth soccer players, across 3 soccer matches over a short period (2 weeks), is relatively "large" and specific to the individual, thus highlighting the need for caution when interpreting physical performance data between games and players.

Sub-maximal heart rate is associated with changes in high-intensity intermittent running ability in professional rugby league players

ABSTRACTObjectives: We examined: (1) relationships among sub-maximal heart rate (sub-maxHR) following 4 minutes of the Yo-Yo intermittent recovery test level 1 (IR1) and maximal-effort performance (distance covered at volitional exhaustion), (2) test re-test reliability of sub-maxHR, and (3) whether changes in maximal-effort Yo-Yo performance are related with changes in sub-maxHR in professional rugby league players.Methods: Yo-Yo IR1 performances of 32 players were assessed before and after 28.5 ± 6.8 days of pre-season training. Relationships between sub-maxHR and maximal-effort Yo-Yo performance, and changes in maximal-effort performance and sub-maxHR were compared.Results: Maximal-effort Yo-Yo IR1 performance and sub-maxHR correlated negatively (r = −0.73, CI −0.85 to −0.55, very large). Coefficient of variation (CV) of sub-maxHR was 2.4% (CI 2.0−3.3%), worthwhile changes of small (0.7 [CI 0.5−1.0%]), moderate (2.1 [CI 1.6−3.0%]) and large (4.3 [CI 3.3−6.1%]) were identified. Training-induced changes in sub-maxHR and Yo-Yo IR1 performance displayed a negative correlation (r = −0.57, CI −0.74 to −0.33, large).Conclusions: sub-maxHR has a very large negative relationship with maximal-effort Yo-Yo IR1 performance. Training-induced changes in sub-maxHR demonstrated a large negative relationship with changes in Yo-Yo IR1 performance. The CV and worthwhile changes can determine meaningful variations in sub-maxHR in professional rugby league players.

Reliability of a laboratory-based long sprint cycling test: applications of the smallest worthwhile changes in performance for repeated measures designs

The aims of the present study were to assess the reliability of long sprint cycling performance in a group of recreationally trained cyclists and to provide thresholds for changes in performance for this particular group of subjects in repeated measures designs through a scale of magnitudes. Repeatability of mean power output during a 1-min cycling time trial was assessed in a group of 15 recreationally trained cyclists (26 ± 5, years, 176 ± 5 cm, 78 ± 8 kg). They were tested on separate days, approximately one week apart. The test and retest values for the whole group of cyclists were 7.0 ± 0.5 W/kg and 6.9 ± 0.6 W/kg (systematic change and 90% confidence limits of -1.0% ± 1.1%). Our results indicated good test-retest reproducibility (typical error of 1.8%, 90% confidence limits of 1.4% to 2.6%; intraclass correlation coefficient of 0.96, confidence limits of 0.91 to 0.99), but suggested a reduction of mean power for the “slower” subjects on retest (-2.0%, 90% confidence limits of ±1.8%). If not monitored, this systematic decrease could interfere in results of studies utilizing groups with similar performance levels, particularly investigating strategies to improve performance in sprint cycling exercises around 1 min. The thresholds for moderate, large, very large and extremely large effects for mean power output on long sprint cycling performance are about 0.4%, 1.3%, 2.3%, 3.6%, and 5.8%, respectively.

Leg Stiffness in Female Soccer Players: Intersession Reliability and the Fatiguing Effects of Soccer-Specific Exercise.

De Ste Croix, MBA, Hughes, JD, Lloyd, RS, Oliver, JL, and Read, PJ. Leg stiffness in female soccer players: intersession reliability and the fatiguing effects of soccer-specific exercise. J Strength Cond Res 31(11): 3052-3058, 2016-Low levels of leg stiffness and reduced leg stiffness when fatigue is present compromise physical performance and increase injury risk. The purpose of this study was to (a) determine the reliability of leg stiffness measures obtained from contact mat data and (b) explore age-related differences in leg stiffness after exposure to a soccer-specific fatigue protocol in young female soccer players. Thirty-seven uninjured female youth soccer players divided into 3 subgroups based on chronological age (under 13 [U13], under 15 [U15], and under 17 [U17] year-olds) volunteered to participate in the study. After baseline data collection, during which relative leg stiffness, contact time, and flight time were collected, participants completed an age-appropriate soccer-specific fatigue protocol (SAFT). Upon completion of the fatigue protocol, subjects were immediately retested. Intersession reliability was acceptable and could be considered capable of detecting worthwhile changes in performance. Results showed that leg stiffness decreased in the U13 year-olds, was maintained in the U15 age group, and increased in the U17 players. Contact times and flight times did not change in the U13 and U15 year-olds, but significantly decreased and increased, respectively, in the U17 age group. The data suggest that age-related changes in the neuromuscular control of leg stiffness are present in youth female soccer players. Practitioners should be aware of these discrepancies in neuromuscular responses to soccer-specific fatigue, and should tailor training programs to meet the needs of individuals, which may subsequently enhance performance and reduce injury risk.

Ecological Validity and Reliability of the Rugby Sevens Simulation Protocol.

To assess the ecological validity of the Rugby Sevens Simulation Protocol (R7SP) and to evaluate its interday reliability. Ten male participants (20 ± 2 y, 74 ± 11 kg) completed 2 trials of the R7SP, separated by 7 d. The R7SP comprised typical running and collision activities, based on data recorded during international rugby sevens match play. Heart rate (HR) was monitored continuously during the R7SP, and the participants' movements were recorded through a 20-Hz global positioning system unit. Blood lactate and rating of perceived exertion were collected before and immediately after the 1st and 2nd halves of the R7SP. The average activity profile was 117 ± 5 m/min, of which 27 ± 2 m/min was covered at high speed, with a calculated energetic demand of 1037 ± 581 J/kg, of which ~40% was expended at a rate above 19 W/kg. Mean HR was 88% ± 4% of maximal HR. Participants spent ~45% ± 27% of time above 90% of maximal HR (t >90%HRmax). There were no significant differences between trials, except for lactate between the halves of the R7SP. The majority of the measured variables demonstrated a between-trials coefficient of variation (CV%) lower than 5%. Blood lactate measurements (14-20% CV) and t >90%HRmax (26% CV) were less reliable variables. In most cases, the calculated moderate worthwhile change was higher than the CV%. The R7SP replicates the activity profile and HR responses of rugby sevens match play. It is a reliable simulation protocol that can be used in a research environment to detect systematic worthwhile changes in selected performance variables.

Effects of Acutely Intermittent Hypoxic Exposure on Running Economy and Physical Performance in Basketball Players.

Kilding, AE, Dobson, BP, and Ikeda, E. Effects of acutely intermittent hypoxic exposure on running economy and physical performance in basketball players. J Strength Cond Res 30(7): 2033-2042, 2016-The aim of this study was to determine the effect of short duration intermittent hypoxic exposure (IHE) on physical performance in basketball players. Using a single-blind placebo-controlled group design, 14 trained basketball players were subjected to 15 days of passive short duration IHE (n = 7), or normoxic control (CON, n = 7), using a biofeedback nitrogen dilution device. A range of physiological, performance, and hematological variables were measured at baseline, and 10 days after IHE. After intervention, the IHE group, relative to the CON group, exhibited improvements in the Yo-Yo intermittent recovery level 1 (+4.8 ± 1.6%; effect size [ES]: 1.0 ± 0.4) and repeated high-intensity exercise test performance (-3.5 ± 1.6%; ES: -0.4 ± 0.2). Changes in hematological parameters were minimal, although soluble transferrin receptor increased after IHE (+9.2 ± 10.1%; ES: 0.3 ± 0.3). Running economy at 11 km·h (-9.0 ± 9.7%; ES: -0.7 ± 0.7) and 13 km·h was improved (-8.2 ± 6.9%; ES: -0.7 ± 0.5), but changes to V[Combining Dot Above]O2peak, HRpeak, and lactate were unclear. In summary, acutely IHE resulted in worthwhile changes in physical performance tests among competitive basketball players. However, physiological measures explaining the performance enhancement were in most part unclear.