Sprint Speed Research Articles

Association Between Hamstrings Eccentric Strength and Sprint Performance in Football Players

Sprint is essential for successful sport performance. Acceleration is necessary for every position in football. The ability to successfully accelerate is also an important determinant for more carried gaming activities. The eccen- tric strength of the hamstrings is an important task in sprint. The aim of our study was to test the correlation between the 30 m sprint and the eccentric strength of the hamstring by NordBord. The sample consisted of 48 professional football players (23.15±4.78 yr.; 180.5±5.42 cm; 76.5±7.94 kg) of the highest Slovak football league. The correlation between 30 m performance and average eccentric hamstring strength has been -0.0826. The correlation suggests that the sprint speed and eccentric strength of the hamstrings have not been associated 0 (t=-0.5619; df=46; p=0.5769). Correlation between 30 m performance and AVG/kg was -0.1317, indicating that the correlation between average weight and speed was not been significant. The eccentric strength has not been associated with a higher speed in the 30-m sprint test. However, more intervention studies are warranted.

Narrative Review on the Use of Sled Training to Improve Sprint Performance in Team Sport Athletes

ABSTRACT Sprinting is a key component for many individual and team sports. Therefore, to enhance sprint performance, various training methods are widely used by coaches and practitioners, including maximum sprint speed and resisted sprint training. Resisted sprinting with sled towing is a method that has recently received considerable attention from the sport science community. However, to date, no consensus exists regarding its acute and chronic effects in team sport athletes. This narrative review aimed to (a) review and analyze the mechanics of sprinting under unresisted and resisted conditions with a specific focus on team sport disciplines; (b) provide a thorough and applied discussion on the importance of considering acute and chronic effects of sled loading on technique, electromyographic activity, and force production, as well as on the role of muscle architecture and neural factors in sled training; (c) analyze the effects of increasing sled loads during acceleration and maximum velocity phases on contact and flight phases, while concomitantly examining kinetic, kinematic, and neuromuscular aspects, because all these factors affect each other and cannot be properly understood in isolation.

The Association Between Sprint Speed Test and Isokinetic Knee Strength in Healthy Male Volleyball Players

Background: Volleyball is a sport with technical elements and explosive power. Objectives: This study investigates the relationship between sprint speed and isokinetic knee strength applied at different angular velocities in male volleyball players. Methods: This study was conducted on 15 volunteer male volleyball players (age; 17 - 25 years, height; 1.75 + 0.12 m). Isomedx 2002 isokinetic dynamometer is employed to measure the isokinetic strength, and a 20 m sprint test is conducted to measure the speed. In measuring knee flexion and isokinetic extension strength, quadriceps and hamstring concentric/eccocentric are measured separately on both legs at 60°/sec angular velocity for three repetitions, at 180°/sec for six repetitions, and at 300°/sec for nine repetitions. For statistical analysis, the Spearman’s correlation test was performed using SPSS 18.0 (SPSS Inc., USA) software. Results: The highest torque value in subjects was recorded on both sides at 60°/sec angular velocity, 180 and 300 degrees, respectively, were lower. There was no significant relationship between speed and isokinetic strength at different angular velocities. Conclusions: Based on our results, the highest peak torque in volleyball players was found to be at 60°/sec angular velocity while no significant correlation was found between isokinetic strength of the knee at different angular velocities and speed of volleyball players.

New Perspectives of the Traditional and Modified 5-0-5 Change of Direction Test

ABSTRACT Change of direction (COD) ability is considered essential for successful participation in many field and court sports. Several COD models that currently exist identify technique, leg strength qualities, and straight sprint speed as the key determinants of COD performance. This narrative review discusses the original COD model, focusing on specific leg strength qualities (concentric, eccentric, isometric, and reactive strength) and their relationship with 5-0-5 COD performance. It is clear from the existing literature that each of these leg strength qualities contributes to the performance of the 5-0-5 COD test; however, it is unclear which are most at play during the phases of performing a COD. This review introduces a new COD model and a way to split the modified 5-0-5 COD test into 4 distinct phases (acceleration, deceleration, 180○ turn, and reacceleration). This new perspective and proposed method of testing provides greater diagnostic value to the modified 5-0-5 COD test and allows coaches and practitioners to be more targeted with feedback and programming to improve COD and sporting performance.

Physical characteristics of elite youth male football players aged 13-15 are based upon biological maturity.

BackgroundOlder and more mature football players have been reported to gain advantages in the selection process during adolescence. The aim of this study was to investigate the influence of skeletal age (SA) on the physical characteristics of elite male football players aged 13–15 years through a cross-sectional study.Methods and MaterialsWe enrolled 167 elite players aged 13–15 from three academic football schools in China, and measured height, body mass, thigh circumference, skinfold (triceps and calf), 10 m/30-m sprint, T-tests (left and right), 5 × 25-m repeated-sprint ability (5 × 25 RSA), standing long jump, and YoYo intermittent recovery test level 1 (YYIR1). Subjects were divided into early-, average-, and late-maturity levels according to their SA and chronological age (CA) based on the following criteria: SA-CA > +1 year, SA-CA = ±1 year, and SA-CA < −1 year, respectively. The differences in parameters among the groups were analyzed using one-way analysis of variance and Bonferroni’s post-hoc test, with statistical significance set at p < 0.05.ResultsRelative to the late-maturing players, the early- and average-maturing players aged 13–15 years were taller, heavier, had a larger thigh circumference, and scored higher on the standing long jump, 30 m sprint, and 5 × 25-RSA (p < 0.05). The physical (except for body-fat percentage) and athletic characteristics of players aged 13–15 were not only significantly influenced by biological maturity, but also increased significantly with CA. The influence of biological maturity on height, 30-m sprints, and 5 × 25-m RSA diminished with age and exerted no significant effect on body-fat percentage and on YYIR1. Late-maturing players exhibited the greatest increase in physical (except for body-fat percentage) and athletic performance (except for the 10-m sprint) compared to players of early and/or average maturity.ConclusionsAlthough early-maturing players aged 13–15 possessed better anthropometric and physical performance than late- and average-maturing players, the growth and development of physical function of late- and average-maturing players was significantly greater, particularly with respect to height, sprint speed, and muscular power.

Responses to artificial selection for locomotor activity: A focus on death feigning in red flour beetle.

Whole-organism performance, including locomotor activity, is an important fitness trait in many animals. Locomotor activity is often classified into sprint speed and locomotor endurance and differences in sprint speed and locomotor endurance affect on other traits such as life-history traits. Previous studies found that locomotor endurance, sprint speed and brain dopamine (DA) levels are correlated with artificial selection for death feigning (an anti-predator behaviour that we refer to as 'death-feigning syndrome') in some insect species. Thus, if the syndrome has a genetic basis, death feigning, sprint speed and brain DA levels may be affected by artificial selection for locomotor endurance. We artificially selected for locomotor endurance over 10generations in the red flour beetle Tribolium castaneum, and established higher (H) and lower activity (L) strains, then compared their death-feigning behaviour, sprint speed and brain DA levels. H-strain beetles exhibited significantly shorter duration of death-feigning, and significantly higher sprint speeds, suggesting variation in death-feigning syndrome. Surprisingly, although brain DA expression affects various animal behaviours, we found no significant differences in the brain DA expressions of H- and L-strain beetles. Thus, our results imply genetic correlations between locomotor endurance, sprint speed and death feigning, but not with brain DA expression, suggesting that differences in the biogenic amine results of our and previous studies may reflect differences in behavioural expression mechanisms.

The Relationship Between Performance and Injury in Junior Australian Football Athletes.

Determine the impact of preseason and between-seasons changes in individual physical performance on injury risk in elite junior Australian football players and if injuries sustained during a season impact subsequent-season performance improvement. This prospective cohort study assessed individual performance measures (sprint speed, jump, agility, and aerobic endurance) during preseason over 4 consecutive seasons. Injury status (injured/not injured) was tracked weekly to determine the relationship between individual performance and in-season injury occurrence. Mixed models were used to determine the relationship between physical performance and injury, and the effect of injury on physical performance improvement. A total of 206 players played 2 consecutive seasons and were included (17.6y, 181.9cm, 75.7kg). Faster players during preseason experienced higher injury incidence (injuries/season) during that playing season (incidence rate ratio = 0.127; P = .034). Injury incidence was not influenced by between-seasons change in any performance measure. Players injured during their first season maintained their aerobic fitness, which declined in noninjured players (d = 0.39; P = .013). Players who sustained a lower-limb injury during their first season saw smaller improvements in sprint speed than players who did not get injured (d = 0.39; P = .035). Faster players experience higher injury incidence than slower players and may require specific prevention interventions. Players who experience a lower-limb injury during the playing season do not improve sprint speed between seasons to the same extent as players who do not get injured, highlighting the need for targeted high-speed running ability development as part of rehabilitation.

Reliability and Validity of a New Taekwondo-Specific Change-of-Direction Speed Test With Striking Techniques in Elite Taekwondo Athletes: A Pilot Study.

The purpose of this study was to examine the test-retest reliability, and convergent and discriminative validity of a new taekwondo-specific change-of-direction (COD) speed test with striking techniques (TST) in elite taekwondo athletes. Twenty (10 males and 10 females) elite (athletes who compete at national level) and top-elite (athletes who compete at national and international level) taekwondo athletes with an average training background of 8.9 ± 1.3 years of systematic taekwondo training participated in this study. During the two-week test-retest period, various generic performance tests measuring COD speed, balance, speed, and jump performance were carried out during the first week and as a retest during the second week. Three TST trials were conducted with each athlete and the best trial was used for further analyses. The relevant performance measure derived from the TST was the time with striking penalty (TST-TSP). TST-TSP performances amounted to 10.57 ± 1.08 s for males and 11.74 ± 1.34 s for females. The reliability analysis of the TST performance was conducted after logarithmic transformation, in order to address the problem of heteroscedasticity. In both groups, the TST demonstrated a high relative test-retest reliability (intraclass correlation coefficients and 90% compatibility limits were 0.80 and 0.47 to 0.93, respectively). For absolute reliability, the TST’s typical error of measurement (TEM), 90% compatibility limits, and magnitudes were 4.6%, 3.4 to 7.7, for males, and 5.4%, 3.9 to 9.0, for females. The homogeneous sample of taekwondo athletes meant that the TST’s TEM exceeded the usual smallest important change (SIC) with 0.2 effect size in the two groups. The new test showed mostly very large correlations with linear sprint speed (r = 0.71 to 0.85) and dynamic balance (r = −0.71 and −0.74), large correlations with COD speed (r = 0.57 to 0.60) and vertical jump performance (r = −0.50 to −0.65), and moderate correlations with horizontal jump performance (r = −0.34 to −0.45) and static balance (r = −0.39 to −0.44). Top-elite athletes showed better TST performances than elite counterparts. Receiver operating characteristic analysis indicated that the TST effectively discriminated between top-elite and elite taekwondo athletes. In conclusion, the TST is a valid, and sensitive test to evaluate the COD speed with taekwondo specific skills, and reliable when considering ICC and TEM. Although the usefulness of the TST is questioned to detect small performance changes in the present population, the TST can detect moderate changes in taekwondo-specific COD speed.

Sex-specific multivariate morphology/performance relationships in Anolis carolinensis.

Animals rely on their ability to perform certain tasks sufficiently well to survive, secure mates and reproduce. Performance traits depend on morphology, and so morphological traits should predict performance, yet this relationship is often confounded by multiple competing performance demands. Males and females experience different selection pressures on performance, and the consequent sexual conflict over performance expression can either constrain performance evolution or drive sexual dimorphism in both size and shape. Furthermore, change in a single morphological trait may benefit some performance traits at the expense of others, resulting in functional trade-offs. Identifying general or sex-specific relationships between morphology and performance at the organismal level thus requires a multivariate approach, as individuals are products of both an integrated phenotype and the ecological environment in which they have developed and evolved. We estimated the multivariate morphology→performance gradient in wild-caught, green anoles (Anolis carolinensis) by measuring external morphology and forelimb and hindlimb musculature, and mapping these morphological traits to seven measured performance traits that cover the broad range of ecological challenges faced by these animals (sprint speed, endurance, exertion distance, climbing power, jump power, cling force and bite force). We demonstrate that males and females differ in their multivariate mapping of traits on performance, indicating that sex-specific ecological demands likely shape these relationships, but do not differ in performance integration.

Beneficial Effects of Warming Temperatures on Embryonic and Hatchling Development in a Low-Latitude Margin Population of the High-Latitude Lizard Lacerta agilis

The effects of warming temperatures on embryonic and hatchling development are critical for determining the vulnerability of species to climate warming. However, these effects have rarely been investigated in high-latitude oviparous species, particularly in their low-latitude margin populations. This study investigated the embryonic and hatchling development and fitness-related traits of a low-latitude margin population of a high-latitude lizard (Lacerta agilis). These traits were examined under present (24°C), moderate warming (27 and 30°C), and severe warming scenarios (33°C). Based on embryonic and hatchling responses to thermal variation, this study aimed to predict the vulnerability of the early life stages of low-latitude margin population of Lacerta agilis to climate warming. The incubation period of the low-latitude margin population of Lacerta agilis decreased as the temperature increased from 24 to 33°C. Hatching success was similar at 24, 27, and 30°C but decreased significantly at 33°C. No differences with temperature were observed for hatchling snout-vent length and hatchling body mass. The sprint speed was higher for hatchlings from temperatures of 24 and 33°C. The growth rate of hatchlings was highest at 30°C; however, the survival rate of hatchlings was not affected by the thermal environment. This study demonstrated that even for a low-latitude margin population of the high-latitude lizard, Lacerta agilis, moderate warming (i.e., 27 and 30°C) would benefit embryonic and hatchling development. This was indicated by the results showing higher hatching success, growth rate, and survival rate. However, if temperatures increase above 33°C, development and survival would be depressed significantly. Thus, low-latitude margin population of high-latitude species Lacerta agilis would benefit from climate warming in the near future but would be under stress if the nest temperature exceeded 30°C.

Comparison of the effects of velocity-based vs. traditional resistance training methods on adaptations in strength, power, and sprint speed: A systematic review, meta-analysis, and quality of evidence appraisal

ABSTRACT We estimated the effectiveness of using velocity feedback to regulate resistance training load on changes in muscle strength, power, and linear sprint speed in apparently healthy participants. Academic and grey literature databases were systematically searched to identify randomised trials that compared a velocity-based training intervention to a ‘traditional' resistance training intervention that did not use velocity feedback. Standardised mean differences (SMDs) were pooled using a random effects model. Risk of bias was assessed with the Risk of Bias 2 tool and the quality of evidence was evaluated using the GRADE approach. Four trials met the eligibility criteria, comprising 27 effect estimates and 88 participants. The main analyses showed trivial differences and imprecise interval estimates for effects on muscle strength (SMD 0.06, 95% CI −0.51–0.63; I2 = 42.9%; 10 effects from 4 studies; low-quality evidence), power (SMD 0.11, 95% CI −0.28–0.49; I2 = 13.5%; 10 effects from 3 studies; low-quality evidence), and sprint speed (SMD −0.10, 95% CI −0.72–0.53; I2 = 30.0%; 7 effects from 2 studies; very low-quality evidence). The results were robust to various sensitivity analyses. In conclusion, there is currently no evidence that VBT and traditional resistance training methods lead to different alterations in muscle strength, power, or linear sprint speed.

Relative Skeletal Maturity and Performance Test Outcomes in Elite Youth Middle Eastern Soccer Players.

This study aimed to explore the influence of differences in relative skeletal maturity on performance test outcomes in elite youth soccer players from the Middle East. We integrated skeletal age and performance assessments using mixed-longitudinal data available for 199 outfield players (chronological age range, 11.7 to 17.8 yr) enrolled as academy student-athletes (annual screening range, 1 to 5 visits). Skeletal age was determined as per the Tanner-Whitehouse II protocol. Relative maturity was calculated as the difference (∆) between Tanner-Whitehouse II skeletal age minus chronological age. Performance test outcomes of interest were 10-m sprinting, 40-m sprinting, countermovement jump height, and maximal aerobic speed. Separate random-effects generalized additive models quantified differences in performance test outcomes by relative skeletal maturity. Estimated differences were deemed practically relevant based on the location of the confidence interval (95% CI) against minimal detectable change values for each performance test outcome. For 40-m sprinting, differences of +0.51 s (95% CI, +0.35 to +0.67 s) and +0.62 s (95% CI, +0.45 to +0.78 s) were practically relevant for relative maturity status of ∆ = -1.5 yr versus ∆ = +0.5 and ∆ = +1 yr, respectively. For countermovement jump height, a difference of -8 cm (95% CI, -10 to -5 cm) was practically relevant for ∆ = -1.5 yr versus ∆ = +1 yr relative maturity status comparison. Effects for 10-m sprinting and maximal aerobic speed were unclear. Integration of skeletal age and performance assessments indicated that conventional maturity status classification criteria were inconsistent to inform player development processes in our sample. Between-player differences in test performance may depend on a substantial delay in skeletal maturation (∆ ≤ -1.5 yr) and the performance outcome measure.

Association Between Success and Unsuccess Rates on Technical Skills and Physical Qualities in Rugby Players

ABSTRACT Purpose: Although physical and technical performance are both fundamental in rugby union teams, the association between these variables in sub-elite players is limited. This study investigated the association between the rate of success and unsuccess in technical skills throughout a season with physical quality variables in sub-elite rugby players. Methods: Twenty-five sub-elite rugby union players (age: 26.4 ± 3.8 years; body mass: 99.68 ± 14.34 kg; height: 1.81 ± 0.07 m) completed the following assessments: (i) broad jump; (ii) 10- and 30-meters sprint speed; (iii) 5-10-5 test; (iv) 1 RM of bench press, chin-up and squat and (v) Yo-Yo fitness test. The rate of success and unsuccess in tackles, attacking rucks and carries were measured during a season. Results: We found that: (i) higher success rates in carries were associated with faster speeds and greater broad jump distance; (ii) higher unsuccess rates in tackles were associated with lower 1 RM chin-up. When controlling for playing position, (iii) higher success rates in carries were associated with 30-meters speed and broad jump distance; (iv) higher success rates in tackles were associated with higher 1 RM chin-up; and (v) higher unsuccess rates in tackles were associated with lower 1 RM chin-up. Conclusions: Success and unsuccess rates in attacking rucks and success in carries were not associated with physical qualities. Therefore, training programs that improve speed, lower limb power and upper limb maximal strength should receive greater attention when seeking to achieve greater success in trying to break the opponent’s defensive line and stop the ball carrier.

The effects of 12-week training between 12-15 years old athlete on physical parameters

Sports are the best way to improve individuals in terms of physic, emotion and society, to achieve cooperation and team spirit and to gain individual to the society. This study aims to determine the importance of sports on social skills and sport orientation, also to determine the effects of 12weeks training on some physical parameters of football players, who didn't have any obstacles in terms of health. A total of 81 subjects (12-15years old) participated in the study. In order to determine some physical, social skills and sport orientation characteristics of sports and non-sports children, flexibility test, push-up test, shuttle test, stop the long jump test, vertical jump test, flamingo balance test and augmentation test, 10,20,30m sprint and ball speed tests, 20m shuttle run test was used. Statistically significant differences were found in all tests except the gain orientation and target orientation, which are the sub-dimensions of body weight test and fitness orientation inventory (p&lt;0.05). As a result, it was observed that the 12-week exercise applied to the children who are actively involved in sports had a positive increase in the physiological and physical parameters. It has been observed that sports provide positive improvements in social skills and sport orientation levels of children.

Can We Modify Maximal Speed Running Posture? Implications for Performance and Hamstring Injury Management.

Sprint kinematics have been linked to hamstring injury and performance. This study aimed to examine if a specific 6-week multimodal intervention, combining lumbopelvic control and unning technique exercises, induced changes in pelvis and lower-limb kinematics at maximal speed and improved sprint performance. Healthy amateur athletes were assigned to a control or intervention group (IG). A sprint test with 3-dimensional kinematic measurements was performed before (PRE) and after (POST) 6 weeks of training. The IG program included 3 weekly sessions integrating coaching, strength and conditioning, and physical therapy approaches (eg,manual therapy, mobility, lumbopelvic control, strength and sprint "front-side mechanics"-oriented drills). Analyses of variance showed no between-group differences at PRE. At POST, intragroup analyses showed PRE-POST differences for the pelvic (sagittal and frontal planes) and thigh kinematics and improved sprint performance (split times) for the IG only. Specifically, IG showed (1)a lower anterior pelvic tilt during the late swing phase, (2)greater pelvic obliquity on the free-leg side during the early swing phase, (3)higher vertical position of the front-leg knee, (4)an increase in thigh angular velocity and thigh retraction velocity, (5)lower between-knees distance at initial contact, and (6)a shorter ground contact duration. The intergroup analysis revealed disparate effects (possibly to very likely) in the most relevant variables investigated. The 6-week multimodal training program induced clear pelvic and lower-limb kinematic changes during maximal speed sprinting. These alterations may collectively be associated with reduced risk of muscle strain and were concomitant with significant sprint performance improvement.

Inter-Unit Consistency and Validity of 10-Hz GNSS Units in Straight-Line Sprint Running.

The present study aimed to investigate the inter-unit consistency and validity of multiple 10-Hz Catapult Global Navigation Satellite System (GNSS) units in measuring straight-line sprint distances and speeds. A total of 13 participants performed one 45.72-m linear sprint at maximum effort while wearing all eight GNSS units at once. Total run distance and peak speed recorded using GNSS units during the sprint duration were extracted for analysis. Sprint time and peak speed were also obtained from video recordings as reference values. Inter-unit consistency was assessed using intraclass correlation coefficients (ICC) and standard errors of measurements (SEM). For a validity test, one-sample t-tests were performed to compare each GNSS unit’s distance with the known distance. Additionally, Wilcoxon signed-rank tests were performed to compare each unit’s peak speed with the reference peak speed measured using video analysis. Results showed poor inter-unit consistency for both distance (ICC = 0.131; SEM = 8.8 m) and speed (ICC = 0.323; SEM 1.3 m/s) measurements. For validity, most units recorded a total distance (44.50 m to 52.69 m) greater than the known distance of 45.72 m and a lower peak speed (7.25 (0.51) m/s) than the video-based reference values (7.78 (0.90) m/s). The present findings demonstrate that there exist variations in distance and speed measurements among different units of the same GNSS system during straight-line sprint running. Practitioners should be aware of the window of errors associated with GNSS measurements and interpret the results with caution. When making comparisons over a season, players should wear the same unit every time if logistically possible.

Predictors of selection into an elite level youth football academy: A longitudinal study

ABSTRACT Talent identification in football is complex. Research regarding talent indicators that predict selection into professional academies is increasingly multi-disciplinary, though is typically cross-sectional, failing to consider whether the rate of change of those indicators influences selection. The aim of this study was to determine if longitudinal changes in talent indicators are associated with selection into a professional football academy. A total of 110 Dutch male football players (aged 8–12) playing in a youth development programme of a professional club were included in the study. Players were assessed regularly on their anthropometry, physical fitness, gross motor coordination, technical ability, and psychosocial capacities over four years. A subset of players was then selected into the academy. Cross-sectional and longitudinal analyses revealed the indicators that best predicted selection. The best indicator was the 30 m sprint speed, with prediction not improving when including other predictors or their rate of change. The individuals that the club ultimately selected at age 12 could have been predicted well above chance levels using the sprint speeds at age nine or ten. The relative consistency of the rate of improvement in indicators across participants meant that the rate at which they developed played little role in selections.

Local Positioning System-Derived External Load of Female and Male Varsity Ice Hockey Players During Regular Season Games.

PurposeThe purposes of this study were to quantify the external load for female and male varsity ice hockey players during regular season games using a local positioning system (LPS), compare LPS-derived external load between sexes and positions, and compare skating distances in absolute and relative speed zones.MethodsData were collected for 21 female (7 defense, 14 forwards; 20.0 ± 1.4 yrs., 69.1 ± 6.7 kg, 167.1 ± 5.4 cm) and 25 male (8 defense, 17 forwards; 21.9 ± 1.1 yrs., 85.9 ± 5.4 kg, 181.1 ± 5.2 cm) varsity ice hockey players. Measures included skating distance (total, and in absolute and relative speed zones), peak skating speed, peak acceleration and deceleration, accumulative acceleration load, and number of accelerations, decelerations, turns, skating transitions, direction changes, and impacts.ResultsFemale and male players had a high external load during games, with average peak skating speeds >28 km/h and average skating distances >4.4 km. Most LPS-derived measures showed greater external load in males than females (p < 0.05). Forwards skated further at higher speeds compared to defense in both sexes (p < 0.001). Skating distances were significantly different when comparing absolute and relative speed zones (p < 0.001), with absolute speed zones potentially overestimating skating at very slow, very fast, and sprint speeds and underestimating skating at slow and moderate speeds.ConclusionThis was the first study to measure external load in female ice hockey players with a LPS. Both female and male varsity players had high external loads during games, with forwards having greater external load at higher intensities and defense having greater external load at lower intensities. Sex and positional differences outline the importance of individualized athlete monitoring.

The relationships between toad behaviour, antipredator defences, and spatial and sexual variation in predation pressure.

BackgroundAnimal behaviour is under strong selection. Selection on behaviour, however, might not act in isolation from other fitness-related traits. Since predators represent outstanding selective forces, animal behaviour could covary with antipredator defences, such that individuals better suited against predators could afford facing the costs of riskier behaviours. Moreover, not all individuals undergo equivalent degrees of predation pressure, which can vary across sexes or habitats. Individuals under lower predation pressure might also exhibit riskier behaviours.MethodsIn this work, I tested these hypotheses on natterjack toads (Epidalea calamita). Specifically, I gauged activity time, exploratory behaviour and boldness in standard laboratory conditions, and assessed whether they correlated with body size and antipredator strategies, namely sprint speed, parotoid gland area and parotoid gland colour contrast. Additionally, I compared these traits between sexes and individuals from an agrosystem and pine grove, since there is evidence that males and agrosystem individuals are subjected to greater predation pressure.ResultsSprint speed as well as parotoid gland contrast and size appeared unrelated to the behavioural traits studied. In turn, body mass was negatively related to activity time, boldness and exploration. This trend is consistent with the fact that larger toads could be more detectable to their predators, which are mostly gape unconstrained and could easily consume them. As predicted, females exhibited riskier behaviours. Nonetheless, agrosystem toads did not differ from pine grove toads in the behavioural traits measured, despite being under stronger predation pressure.

Simulated Game-Based Ice Hockey Match Design (Scrimmage) Elicits Greater Intensity in External Load Parameters Compared With Official Matches.

ObjectiveA limited number of studies have explored the external load experienced in indoor sports such as ice hockey, and few the link between training and match performance. As a paucity exists within this topic, this study explored whether a simulated match design (i.e., scrimmage) could be representative of official match demands and elicit similar external loads as in official matches in a group of elite youth male ice hockey players.MethodsA total of 26 players were monitored during eight official and four simulation matches using a Local Positioning System. Total distance, max velocity, slow (0–10.9 km/h), moderate (11–16.9 km/h), high (17.0–23.9 km/h), and sprint (>24 km/h) speed skating distance, distance per min, PlayerLoadTM, PlayerLoadTM per min, high-intensity events (HIEs) (>2.5 m/s−2), acceleration (ACCs), decelerations (DECs), and change of directions (CODs) were extracted from the tracking devices. A two-level regression analysis was conducted to compare the difference between match types when controlling for time on ice, match day, and position.ResultsBetween match-type results showed a credible difference in all variables except max velocity and ACCs. Distance per min was 27.3% higher during simulation matches and was explained by a 21.3, 24.1, and 14.8% higher distance in sprint-, high-, and moderate speed skating distance, while slow speed-skating distance was 49.2% lower and total distance only trivially different from official to simulation matches. Total PlayerLoadTM was 11.2% lower, while PlayerLoadTM per min was 8.5% higher during simulation matches. HIEs, CODs, and DECs were 10.0, 11.9, and 22.3% higher during simulation matches.ConclusionThe simulated match design is related to official match demands with comparable match-time, playing time, number of shifts, and shift duration. However, simulation matches provoked a higher external load output compared with official matches, possibly explained by a more continuous movement design. A game-based simulation match design can therefore be utilized when match-related actions at high intensity are warranted.