Effects of different strength and velocity training programs on physical performance in youth futsal players

Futsal is a high intensity team sport with intermittent actions of short duration, so it is necessary to include different training strategies to improve explosive actions. There is a gap in the scientific literature regarding training programs that improve the performance of young futsal players. The aim of this study was to determine the effects of different strength and velocity training programs on lower body physical performance in youth futsal players. Forty-two youth futsal players were divided into control group (CG, n = 14) and a strength intervention group (SG, n = 14), which included a weekly session for 8 weeks of eccentric strength training, plyometrics and core strengthening, and a velocity intervention group (VG, n = 14), which included a weekly session during 8 weeks of training with linear speed exercises and with change of direction, accelerations with resistance bands and core strengthening. SG significantly improved horizontal jump (HJ) (p:0.02), V-CUT (p:0.91) and change of direction deficit (CODD) (p:0.01). VG showed significant improvements in HJ (p:0.01), in 25 m sprint (p:0.01), in total repeated sprint ability time (p:0.01), in V-CUT (p:0.01) and in CODD (p:0.01). SG showed significant intergroup differences (p:0.01) in COD variables with respect to CG and VG. In conclusion, SG and VG showed significant improvements in lower body performance variables in youth futsal players. In addition, the SG has substantial changes in COD compared to the other two groups, so it has a greater effect.

Modern software and physical education: can online training enhance gym training?

BACKGROUND

This study discusses the effectiveness of a 12-week intervention aimed at improving squat jump and sprint performance among second-year sports students.

METHODS

The students were randomly divided into experimental (n = 89) and control (n = 92) groups. In addition to gym training, students of the experimental group also underwent online PE training. The students' performance in Squat Jumps, 30 m sprint, and Progressive Aerobic Cardiovascular Endurance Run (PACER), as well as their situational motivation, were assessed before and after the intervention. Furthermore, the students assessed their physical activity weekly using self-reports.

RESULTS

The implementation of online training has positively impacted intrinsic and identified motivation, as well as external regulation; however, it was less effective in reducing amotivation compared to traditional gym-based training.

CONCLUSIONS

The findings of the study contribute to the data synthesis on the expediency of using modern software in physical education.

Individual In-Situ GPS-Derived Acceleration-Speed Profiling: Toward Automatization and Refinement in Male Professional Rugby Union Players

BACKGROUND

Recently a proof-of-concept was proposed to derive the soccer players' individual in-situ acceleration-speed (AS) profile from global positioning system (GPS) data collected over several sessions and games. The present study aimed to propose an automatized method of individual GPS-derived in-situ AS profiling in a professional rugby union setting.

METHOD

AS profiles of forty-nine male professional rugby union players representing 61.5 million positions, from which acceleration was derived from speed during 51 training sessions and 11 official games, were analyzed. A density-based clustering algorithm was applied to identify outlier points. Multiple AS linear relationships were modeled for each player and session, generating numerous theoretical maximal acceleration (A0), theoretical maximal running speed (S0) and AS slope (ASslope, i.e., overall orientation of the AS profile). Each average provides information on the most relevant value while the standard deviation denotes the method accuracy. In order to assess the reliability of the AS profile within the data collection period, data were compared over two 2-week phases by the inter-class correlation coefficient. A0 and S0 between positions and type of sessions (trainings and games) were compared using ANOVA and post hoc tests when the significant threshold had been reached.

RESULTS

All AS individual profiles show linear trends with high coefficient of determination (r2 > 0.81). Good reliability (Inter-class Correlation Coefficient ranging from 0.92 to 0.72) was observed between AS profiles, when determined 2 weeks apart for each player. AS profiles depend on players' positions, types of training and games. Training and games data highlight that highest A0 are obtained during games, while greatest S0 are attained during speed sessions.

CONCLUSIONS

This study provides individual in-situ GPS-derived AS profiles with automatization capability. The method calculates an error of measurement for A0 and S0, of paramount importance in order to improve their daily use. The AS profile differences between training, games and playing positions open several perspectives for performance testing, training monitoring, injury prevention and return-to-sport sequences in professional rugby union, with possible transferability to other sprint-based sports.

KEY POINTS

AS profiles computed from rugby union GPS data provide positional benchmarks during training and competition. This study provides automatic detection of atypical data and the computation of error measurement of theoretical maximal acceleration and speed components. This refinement constitutes a step forward for a daily use of ecological data by considering data collection and method reliabilities. This easy-to-implement approach may facilitate its use to the performance management process (talent identification, training monitoring and individualization, return-to-sport).

The effect of high-intensity plyometric training on anaerobic performance parameters: a pilot study in U17 elite A league

The aim of this study was to examine the effects of high-intensity plyometric training (HIPT) on some parameters in elite soccer players in the U17. Volunteer soccer players were randomly divided into two groups according to their positions: the regular training (RT) group (age: 16.71 ± 0.47 years; stature: 163.46 ± 3.31 cm; body weight: 61.04 ± 1.59 kg) and the HIPT group (age: 16.64 ± 0.50 years; stature: 165.60 ± 3.03 cm; body weight: 59.76 ± 1.92 kg), and each group included five defenders, five midfielders, and four attackers. While the RT group did only routine soccer training, the HIPT group performed high-intensity plyometric training three days a week in addition to routine soccer training. In the study, body weight, stature, sprint (10 m, 30 m, and 40 m), jump (standing long jump, right and left-limb triple hop) and 5-0-5 change of direction speed test measurements of the soccer players were taken. Skewness and Kurtosis values obtained from the pre-test and post-test measurements were calculated to test whether the normality assumption of the study was met. A mixed measure two-way ANOVA test was used to determine the difference between the pre-test and post-test. The significance was set as p < 0.05. The results indicated that 8-week high- intensity plyometric training provided more improvement in measured performance parameters than routine soccer training. As a result, when the data obtained is examined, it can be said that HIPT had better values in sprint, jump, and change of direction parameters, so plyometric training was more beneficial for anaerobic parameters than routine soccer training in children. It is recommended that the trainers make their plans considering these results.

Mechanical and Metabolic Power in Accelerated Running-PART I: the 100-m dash

PURPOSE

Acceleration phases require additional mechanical and metabolic power, over and above that for running at constant velocity. The present study is devoted to a paradigmatic example: the 100-m dash, in which case the forward acceleration is very high initially and decreases progressively to become negligible during the central and final phases.

METHODS

The mechanical ([Formula: see text]) and metabolic ([Formula: see text]) power were analysed for both Bolt's extant world record and for medium level sprinters.

RESULTS

In the case of Bolt, [Formula: see text] and [Formula: see text] attain peaks of ≈ 35 and ≈ 140 W kg-1 after ≈ 1 s, when the velocity is ≈ 5.5 m s-1; they decrease substantially thereafter, to attain constant values equal to those required for running at constant speed (≈ 18 and ≈ 65 W kg-1) after ≈ 6 s, when the velocity has reached its maximum (≈ 12 m s-1) and the acceleration is nil. At variance with [Formula: see text], the power required to move the limbs in respect to the centre of mass (internal power, [Formula: see text]) increases gradually to reach, after ≈ 6 s a constant value of ≈ 33 W kg-1. As a consequence, [Formula: see text] ([Formula: see text]) increases throughout the run to a constant value of ≈ 50 W kg-1. In the case of the medium level sprinters, the general patterns of speed, mechanical and metabolic power, neglecting the corresponding absolute values, follow an essentially equal trend.

CONCLUSION

Hence, whereas in the last part of the run the velocity is about twice that observed after ≈ 1 s, [Formula: see text] and [Formula: see text] are reduced to 45-50% of the peak values.

Effective playing time affects physical match performance in soccer: An analysis according to playing position

This study aimed to analyse the influence of effective playing time on physical match performance according to playing position in professional soccer. Official match data from 267 matches (3,731 single observations) during the 2018/2019 season of the German Bundesliga were used and the effective playing time (duration of play after subtracting the time taken up by stoppages, substitutions, injuries, and goals) was captured for each match. The physical match performance parameters total distance, high-intensity distance, sprinting distance, maximum velocity, and accelerations were analysed. Players were categorized as central defender, wide defender, central defensive midfielder, central offensive midfielder, wide midfielder, and forward. Effective playing time influenced physical match performance, with total distance and accelerations (r = 0.48-0.61) being the most and high-intensity distance, sprinting distance, and maximum velocity (r = -0.17-0.03) the least affected parameters. Players covered on average 10% more total distance and performed 13% more accelerations, while sprinting 7-10% less in matches with long (> 65 min) compared to short (< 50 min) effective playing times. The influence of effective playing time was rather similar between playing positions. Still, physical performance of wide midfielders and forwards partly deviated from the pattern observed in the other positions. Coaches and practitioners should be aware that effective playing time influences physical match performance in the German Bundesliga, while special attention should be given to wide midfielders and forwards. Effective playing time and its general and position-specific effects should be taken into account when interpreting physical match performance, thereby facilitating load management practices and training design.

Effects of combined plyometric, strength and running technique training program on change-of-direction and countermovement jump: A two-armed parallel study design on young soccer players

CONTEXT AND OBJECTIVE

Players must be capable to have a good change-of-direction (COD) skill aiming to be the fastest as possible to react immediately to the opponent or even to help players to be more agile since COD is a physical determinant of agility. Thus, the aim of this study was to test the effects of a six-week combined training intervention in the COD and countermovement jump (CMJ) of young soccer players, while comparing with a control group only performing the regular field-based training sessions.

METHODS

A sample of 80 non-professional players (40 experimental group and 40 control group) between the ages of ten and twelve was taken [(Age: 10.70 ± 1.02)]. The tests that were carried out from the beginning to the end of the intervention were: CMJ test, 505COD Test and Illinois Test. Paired sample t-test was used for determining differences as a repeated measures analysis (pre- post). An ANCOVA test was performed using the pretest as a covariate and the times pre and post as factors.

RESULTS AND CONCLUSIONS

Repeated measures ANCOVA revealed significant influence of baseline level on the 5-0-5 COD (p = 0.001; ηp2=0.170), the Illinois (p = 0.018; ηp2=0.070) and the CMJ (p = 0.047; ηp2=0.050). Significant interactions group*time (p < 0.001; ηp2=0.137), 5-0-5 COD (p < 0.001; ηp2=0.274), and CMJ (p < 0.001; ηp2=0.392) were found, while no significant interactions were found in Illinois (p = 0.293; ηp2=0.014). The current research revealed that a combined training intervention consisting of strength training, plyometrics, and running techniques can be significantly beneficial for improving COD performance and CMJ.

Fatigue does not increase limb asymmetry or induce proximal joint power shift in habitual, multi-speed runners

During prolonged jogging, joint moment and work tend to decrease in the distal (ankle) joint but increase at proximal (hip/knee) joints as performance fatigue manifests, and such adaptations might be expected to occur in sprinting. Fatigue is also thought to increase inter-limb asymmetries, which is speculated to influence injury risk. However, the effects of fatigue on sprint running gait have been incompletely studied, so these hypotheses remain untested. Using statistical parametric mapping, we compared 3-D kinematics and ground reaction force production between the dominant (DL) and non-dominant (NDL) legs of 13 soccer players during both non-fatigued and fatigued sprint running. Contrary to the tested hypotheses, relative between-leg differences were greater in non-fatigued than fatigued sprinting. DL generated higher propulsive impulse due to increased ankle work, while NDL exhibited greater vertical impulse, potentially due to greater hip flexion prior to downward foot acceleration. Whilst few changes were detected in DL once fatigued, NDL shifted towards greater horizontal force production, largely resulting from an increase in plantar flexion (distal-joint) moments and power. After fatiguing running, inter-limb asymmetry was reduced and no distal-to-proximal shift in joint work was detected. These adaptations may attenuate decreases in running speed whilst minimising injury risk.

Most Common Movements Preceding Goal Scoring Situations in Female Professional Soccer

This study aimed to assess movements occurring during goal scoring situations in a female professional league.Data from all the goals on the Women's Super League 2018/2019 were collected through time-motion analysis using a modified version of the Bloomfield Movement Classification with differences analysed through chi-square. Analysis was performed on players (assistant, scorer [attackers], defender of assistant and defender of scorer [defenders]), movements, intensities and directions.Linear advancing motion (walking, jogging, running or sprint) (total percentage [95% CI] 37% attackers and 32.7% defenders) was the most common action preceding a goal, followed by deceleration (21.5% attackers; 18.4% defenders) and turn (19.2% attackers; 17.6% defenders). Other movements involved but with lower percentages were change in angle run (cut and arc run), ball blocking, lateral advancing motion (crossover and shuffle) and jumps. Players displayed similar tendencies but presented variations based on the role, with attackers performing more linear actions, subtle turns and cuts and defenders more ball blocking actions, lateral movements and high intensity linear actions and decelerations. Assistant performed the less percentage of involvements with at least 1 high intensity action (67.4%), scorer and defender of assistant showed similar values (86.3% and 87.1%), while defender of scorer had the highest percentage (97.3%).This study shows the importance of linear actions with other movements also being of high significance but with differentiated characteristics based on the role. This study could help practitioners design drills for the enhancement of physical capabilities related to movements occurring in goal scoring situations.

Reliability of individual acceleration-speed profile in-situ in elite youth soccer players

The aims of this study were to describe differences in the acceleration-speed (A-S) profile in-situ and to assess the week-to-week reliability of the A-S profile in-situ over a given training cycle of elite youth soccer players, in relation to the number of sessions included and analyse the effect of the inclusion or not of a specific sprint session. In this retrospective study, 18 male elite U19 football players (179.4 ± 7.1 cm; 69.0 ± 9.5 kg) participated. GPS data collected from three consecutive typical training weeks were used to calculate different combinations of A-S profile in-situ variables (theoretical maximal acceleration [A₀], theoretical maximal speed [S₀] and the slope of the acceleration-speed [AS_slope]). The number (and content) of sessions affected mainly S₀ while A₀ remained similar with or without a sprint session. The reliability of the A-S profile in-situ is more related to the spread of points rather than a specific number of sessions (and thus points) and was improved when a high percentage of maximum speed (i.e. ≥ 95%) was reached. The present study showed low week-to-week variability for A₀, S₀ and AS_slope. However, practitioners need to make sure that the values cover a sufficient range of raw data [20-95% of maximum speed] to build a clear and consistent linear regression, and in turn extrapolate meaningful A-S profile values.

Aerobically trained older adults show impaired resting, but preserved exercise-induced circulating progenitor cell count, which was not improved by sprint interval training

Older adults exhibit a reduced number and function of CD34 + circulating progenitor cells (CPC), a known risk factor for cardiovascular disease. Exercise promotes the mobilisation of CPCs from bone marrow, so whether ageing per se or physical inactivity in older age reduces CPCs is unknown. Thus, this study examined the effect of age on resting and exercise-induced changes in CPCs in aerobically trained adults and the effect of 8 weeks of sprint interval training (SIT) on resting and exercise-induced CPCs in older adults. Twelve young (22-34 years) and nine older (63-70 years) adults participated in the study. Blood was sampled pre and immediately post a graded exercise test to exhaustion in both groups. Older participants repeated the process after 8 weeks of SIT (3 × 20 s 'all-out' sprints, 2 × a week). Total CPCs (CD34⁺) and endothelial progenitor cells (EPCs: CD34⁺KDR⁺) were determined by flow cytometry. Older adults exhibited lower basal total CD34⁺ CPCs (828 ± 314 vs. 1186 ± 272 cells·mL^-1, p = 0.0149) and CD34⁺KDR⁺ EPCs (177 ± 128 vs. 335 ± 92 cells·mL^-1, p = 0.007) than younger adults. The maximal exercise test increased CPCs in young (CD34⁺: p = 0.004; CD34⁺KDR⁺: p = 0.017) and older adults (CD34⁺: p < 0.001; CD34⁺KDR⁺: p = 0.008), without difference between groups (p = 0.211). SIT did not alter resting or exercise-induced changes in CPCs in the older cohort (p > 0.232). This study suggests age per se does not impair exercise-induced CPC counts, but does lower resting CPC counts.

Force-velocity profile in sprinting: sex effect

The ability to produce muscle power during sprint acceleration is a major determinant of physical performance. The comparison of the force-velocity (F-v: theoretical maximal force, F₀; velocity, v₀ and maximal power output, P_max) profile between men and women has attracted little attention. Most studies of sex differences have failed to apply a scaling ratio when reporting data. The present study investigated the sex effect on the F-v profile using an allometric model applied with body mass (BM), fat-free mass (FFM), fat-free mass of the lower limb (FFMLL), cross-sectional area (CSA) and leg length (LL) to mechanical parameters. Thirty students (15 men, 15 women) participated. Raw velocity-time data for three maximal 35 m sprints were measured with a radar. Mechanical parameters of the F-v relationship were calculated from the modelling of the velocity-time curve. When F₀ and P_max were allometrically scaled with BM (p = 0.538; ES = 0.23) and FFM (p = 0.176; ES = 0.51), there were no significant differences between men and women. However, when the allometric model was applied to P_max with FFMLL (p = 0.015; ES = 0.52), F₀ with CSA (p = 0.016; ES = 0.93) and v₀ with LL (p ≤ 0.001; ES = 1.98) differences between men and women persisted. FFM explained 83% of the sex differences in the F-v profile (p ≤ 0.001). After applying an allometric model, sex differences in the F-v profile are explained by other factors than body dimensions (i.e., physiological qualitative differences).

Effects of substitute allowance on match activity characteristics in Japanese professional football across 2019, 2020, and 2021 seasons

This study aimed to examine the effects of substitute player allowance per match on running performance in Japanese professional football over three consecutive seasons with different numbers of maximum substitutes. Match running performance was obtained from all outfield players in the official matches of the 1st Division of the Japan Professional Football League over three seasons (2019/2020/2021; 22291 player files) by a 4th generation TRACAB® system which provided the total distance covered (TD) and the number of sprinting runs (SP; ≥24.0 km/h for≥1.0 s). The players were divided according to play time: full match (STA), replaced during match (REP), and substitutes during match (SUB). The number of SUBs increased significantly from 2019 to 2021 (p < 0.05). SUB had a significantly higher average speed than STA and REP. The analysis of covariance with the number of recovery days, ambient temperature, and relative humidity as covariates revealed that the TD and SP significantly differed based on the number of SUBs (p < 0.05). Stepwise regression analysis showed that the number of SUBs significantly contributed to the TD and SP. These results suggest that the new law, which increased the maximum SUB allowance from three to five, improved the match running performance in Japanese professional football.

Correlations between horizontal jump and sprint acceleration and maximal speed performance: a systematic review and meta-analysis

Objectives

The purpose of this study is to determine the associations between horizontal jump and sprint acceleration, as well as maximal speed performance.

Methods

A systematic literature search was performed using PubMed, MEDLINE (EBSCOhost), and Web of Science. The studies that were included in this review must meet the following criteria: (1) well-trained individuals over the age of 18 years old; (2) Pearson's correlation coefficients between sprint time and horizontal jump distance were provided; (3) the sprint distance was limited to 0-100 m. The quality of the studies was assessed using a modified version of the Downs and Black Quality Index test. A random-effects model was used to determine the effect sizes, and heterogeneity between studies was examined using the Q statistic and I².

Results

From the identified 2,815 studies, 27 studies were included in this study (two from reference lists). The sprint time of the sprint acceleration phase was moderately and negatively correlated with the standing long jump (r =  - 0.45, z = 7.48, p < 0.001), single leg standing long jump (r =  - 0.48, z = 3.49, p < 0.001) and horizontal drop jump distance (r =  - 0.48, z = 3.49, p < 0.001), and was largely and negatively correlated with multiple jump distance (r =  - 0.69, z = 6.02, p < 0.001). Out of five studies assessed the standing triple jump, three studies reported significant positive association with the sprint acceleration performance. The sprint time of maximal speed phase was very largely and negatively associated with standing long jump distance (r =  - 0.73, z = 4.44, p < 0.001) and multiple jump distance (r =  - 0.76, z = 6.86, p < 0.001).

Conclusions

This review indicates the moderate to very large associations between horizontal jump and sprint acceleration and maximal speed performance, and the highest magnitude of associations between them is found in the multiple jump. Moreover, compared to the sprint acceleration performance, there are greater associations between maximal speed performance and standing long jump and multiple jump distance.

Effect of electromyostimulation and plyometrics training on sports-specific parameters in badminton players

Badminton is one of the world's most popular racquet sports, demanding motor skills such as agility and vertical jump mainly for striking a shuttlecock. This study compared the effects of four weeks of plyometric training and electromyostimulation of knee extensor and ankle plantar flexor muscles on agility, 30-m sprint, lower limb explosive power and jumping ability amongst badminton players. State-level badminton players (n ​= ​90) were randomly allocated into three groups: plyometric (PG), electromyostimulation (EG) and control group (CG), each with 30 players. Randomized-to-Groups Pretest-Posttest Design with two experimental (plyometric and electromyostimulation) groups and a control group was used. The plyometric training was carried out two times/week while the EMS training was four times/week for four weeks. The control group did not receive any intervention. All three groups continued their general badminton training throughout the study. Players were assessed for agility, a 30-m sprint, a standing broad jump and a vertical jump height before and after four weeks. A significant improvement (p ​= ​0.01) in 30-m sprint time was observed (3.83%) in PG as compared to controls. Jumping ability was significantly improved in both the PG and EG in comparison to the controls (4.45%, p ​= ​0.003 for PG and 3.95%, p ​= ​0.048 for EG). No significant improvement was found in agility and lower limb explosive power in either of the PG or EG groups in comparison to the controls. Plyometric training showed significant improvement in sprint time and jumping ability, whereas electromyostimulation training showed significant improvement only in jumping ability.

Effect of plyometric training and neuromuscular electrical stimulation assisted strength training on muscular, sprint, and functional performances in collegiate male football players

Background

The study's objective was to analyze the influence of an 8-week neuromuscular electrical stimulation (NMES) with a plyometric (PT) and strength training (ST) program on muscular, sprint, and functional performances in collegiate male football players.

Methods

Sixty collegiate male football players participated in this randomized controlled trial single-blind study. All the participants were randomly divided into two groups: (1) NMES group (Experimental, n = 30) who received NMES assisted ST and (2) sham NMES group (Control, n = 30) who received sham NMES assisted ST. In addition, participants from both groups received a PT program; both groups received intervention on three days a week for 8-weeks. The study's outcomes, such as muscular, sprint, and functional performances, were assessed using a strength test (STN) for quadriceps muscle, sprint test (ST), and single-leg triple hop test (SLTHT), respectively, at baseline pre-intervention and 8-week post-intervention. The interaction between group and time was identified using a mixed design (2 × 2) ANOVA.

Results

Significant difference found across the two time points for the scores of STN: F (1.58) = 5,479.70, p < 0.05; SLTHT: F (1.58) = 118.17, p < 0.05; and ST: F (1.58) = 201.63, p < 0.05. Similarly, the significant differences were found between groups averaged across time for the scores of STN: F (1.58) = 759.62, p < 0.05 and ST: F (1.58) = 10.08, p < 0.05. In addition, after 8-week of training, Cohen's d observed between two groups a large to medium treatment's effect size for the outcome STN (d = 10.84) and ST (d = 1.31). However, a small effect size was observed only for the SLTHT (d = 0.613).

Conclusions

Findings suggest that the effect of PT and ST with either NMES or sham NMES are equally capable of enhancing muscular, sprint, and functional performances in collegiate male football players. However, PT and ST with NMES have shown an advantage over PT and ST with sham NMES in improving muscular performance and sprint performance among the same participants.

Acute effects from the half-squat performed using a repetition versus differential approach in youth soccer players

Background

Over the last years there have been a wide body of research exploring the best strategies to promote acute enhancements in players’ performance. Despite that, most studies have been focused on adult and elite players, and different results may be identified when considering players from lower levels of performance and belonging to youth categories. In addition, most studies conducted in this domain focused in repetitive movement patterns, and while adding variability has been considered as a useful approach to enhance players’ performance at short and long-term perspectives, less is known regarding it applicability to acute enhance players physical performance. Therefore, this study aimed to compare the acute enhancement effects of performing the half-squat in a flywheel ergometer between a more-repetitive approach (low noise) and a more variable approach (differential learning, high noise) in youth soccer players.

Methods

A total of sixteen players (age = 16.2 ± 0.6 years) was exposed to four conditions in a randomized order: (1) repetitive intervention for 30 s; (2) repetitive intervention for 10-min; (3) differential learning intervention for 30 s; (4) differential learning intervention for 10-min. Each condition consisted in 3 sets of 6 repetitions of eccentric half squats performed in a flywheel ergometer. Countermovement jump, 10 m and 30 m linear sprint, and change-of-direction ability were measured every session at baseline (pre-test) and after each protocol (post-test).

Results

No potentiation effect was observed overall with any of the interventions. In addition, no differences between protocols were found for sprinting. However, the repetitive intervention impaired jumping performance for both 30 s (small effects, p ≤ .05) and 10-min intervals (small effects, p ≤ .05), as well as in the change-of-direction task for 30 s (p ≤ .05).

Conclusions

These results may be due to the players’ low experience in eccentric flywheel training. Despite these findings, individual potentiation responses emerged from both protocols when considering the individual responses, reinforcing the need to establish more personalized approaches.

Acute effects of dynamic versus foam rolling warm-up strategies on physical performance in elite tennis players

To date, there is a lack of information about the optimal conditions of the warm-up to lead to a better performance in elite tennis players. The aim of this study was to compare the effects of two different warm-up protocols (dynamic vs. self-myofascial release with foam rolling) on neuromuscular variables associated with physical determinants of tennis performance. Using a crossover randomised experimental design, eleven professional men tennis players (20.6 ± 3.5 years) performed either a dynamic warm-up (DWU) or a self-myofascial release with foam rolling (SMFR) protocol. DWU consisted of 8 min of dynamic exercises at increasing intensity and SMFR consisted of 8 min of rolling on each lower extremity unilaterally. Just before (baseline) and after completing warm-up protocols, players performed a countermovement jump (CMJ), the 5-0-5 agility test, a 10-m sprint test and the Straight Leg Raise and Thomas tests to assess range of motion. Compared to baseline, the DWU was more effective to reduce the time in the 5-0-5 test than SMFR (-2.23 vs. 0.44%, respectively, p = 0.042, ηp² = 0.19). However, both warm-up protocols similarly affected CMJ (2.32 vs. 0.61%, p = 0.373, ηp² = 0.04) and 10-m sprint time changes (-1.26 vs. 1.03%, p = 0.124, ηp² = 0.11). Changes in range of motion tests were also similar with both protocols (p = 0.448–1.000, ηp² = 0.00–0.02). Overall, both DWU and SMFR were effective to prepare well-trained tennis players for highly demanding neuromuscular actions. However, DWU offered a better preparation for performing change of direction and sprint actions, and hence, in high-performance tennis players, the warm-up should include dynamic exercises.

Effects of motor skill level and speed on movement variability during running

Variability in movement is an informative biological feature. This study aimed to examine the effects of motor skill level and running speed on movement variability. Twenty-nine male college students (fourteen athletes and fifteen non-athletes) participated in this study. All participants performed three motor tasks: 3 m/s running, 5 m/s running, and sprint running. Lower-limb kinematic data were acquired using a 16-camera infrared motion capture system. Lower-limb coordination during the stance phase was quantified using a continuous relative phase (CRP) method for interlimb (hip-hip, knee-knee, ankle-ankle) and intralimb (hip-knee, knee-ankle). The variabilities of stride length, stride cadence, joint angles, intralimb CRP, and interlimb CRP were calculated as standard deviations of each measurement. The results revealed that there were significant interaction effects between motor skill level and speed on movement variability for stride length (p = 0.047), ankle angle during propulsive phase (p = 0.001), knee-ankle CRP during propulsive phase (p = 0.007) and knee-knee CRP during propulsive phase (p = 0.009). Athletes showed greater angle variability, coordination variability and lower stride length variability during sprinting (all p < 0.05). In contrast, no between groups variability difference was observed when jogging at fixed lower speeds (all p > 0.05). Movement variability was greater for sprinting compared to jogging. Skill level was found to differentially affect the role of coordination variability in sprint performance. For athletes, hip-knee deviation phase and hip-hip deviation phase during braking phase were negatively correlated with sprinting speed (r = -0.563 and -0.642, respectively; both p < 0.05). For non-athletes, hip-knee deviation phase was positively correlated with sprinting speed (r = 0.581, p = 0.023). In conclusion, stride length become more stable, joint angle and coordination become more variable with long-term training. Results of this study also suggest that the relationship between coordination variability and performance is complicated and may depend on motor skill level. More longitudinal studies are needed to definitively determine the relationship between movement variability and performance.

Running at altitude: the 100-m dash

PURPOSE

Theoretical 100-m performance times (t_100-m) of a top athlete at Mexico-City (2250 m a.s.l.), Alto-Irpavi (Bolivia) (3340 m a.s.l.) and in a science-fiction scenario "in vacuo" were estimated assuming that at the onset of the run: (i) the velocity (v) increases exponentially with time; hence (ii) the forward acceleration (a_f) decreases linearly with v, iii) its time constant (τ) being the ratio between v_max (for a_f = 0) and a_{f max} (for v = 0).

METHODS

The overall forward force per unit of mass (F_tot), sum of a_f and of the air resistance (F_a = k v², where k = 0.0037 J·s²·kg^-1·m^-3), was estimated from the relationship between a_f and v during Usain Bolt's extant world record. Assuming that F_tot is unchanged since the decrease of k at altitude is known, the relationships between a_f and v were obtained subtracting the appropriate F_a values from F_tot, thus allowing us to estimate in the three conditions considered v_max, τ, and t_100-m. These were also obtained from the relationship between mechanical power and speed, assuming an unchanged mechanical power at the end of the run (when a_f ≈ 0), regardless of altitude.

RESULTS

The resulting t_100-m amounted to 9.515, 9.474, and 9.114 s, and to 9.474, 9.410, and 8.981 s, respectively, as compared to 9.612 s at sea level.

CONCLUSIONS

Neglecting science-fiction scenarios, t_100-m of a world-class athlete can be expected to undergo a reduction of 1.01 to 1.44% at Mexico-City and of 1.44 to 2.10%, at Alto-Irpavi.

Individual acceleration-speed profile in-situ: A proof of concept in professional football players

Assessing football players' sprint mechanical outputs is key to the performance management process (e.g. talent identification, training, monitoring, return-to-sport). This is possible using linear sprint testing to derive force-velocity-power outputs (in laboratory or field settings), but testing requires specific efforts and the movement assessed is not specific to the football playing tasks. This proof-of-concept short communication presents a method to derive the players' individual acceleration-speed (AS) profile in-situ, i.e. from global positioning system data collected over several football sessions (without running specific tests). Briefly, raw speed data collected in 16 professional male football players over several training sessions were plotted, and for each 0.2 m/s increment in speed from 3 m/s up to the individual top-speed reached, maximal acceleration output was retained to generate a linear AS profile. Results showed highly linear AS profiles for all players (all R² > 0.984) which allowed to extrapolate the theoretical maximal speed and accelerations as the individual's sprint maximal capacities. Good reliability was observed between AS profiles determined 2 weeks apart for the players tested, and further research should focus on deepening our understanding of these methodological features. Despite the need for further explorations (e.g. comparison with conceptually close force-velocity assessments that require, isolated and not football-specific linear sprint tests), this in-situ approach is promising and allows direct assessment of football players within their specific acceleration-speed tasks. This opens several perspectives in the performance and injury prevention fields, in football and likely other sprint-based team sports, and the possibility to "test players without testing them".

The relation between sprint power and road time trial performance in elite para-cyclists

OBJECTIVES

Whilst cycling performance has been studied extensively, very little is known about the performance of para-cyclists. This study assessed the relation between sprint power and road time trial performance in elite para-cyclists, and whether this relation differed based on impairment type and type of bike used.

DESIGN

Cross-sectional.

METHODS

During international para-cycling events, 168 athletes (88 bicycles, 17 tricycles, 56 recumbent handbikes and 7 kneeling handbikes) performed 20-s sport-specific sprint tests (mean power output (POmean) W), and their road time trial performance (average speed (km/h)) was taken from the official results. Multilevel regression models to assess the relation of sprint with time trial performance were composed for i. leg-cyclists: bicycle and tricycle and ii. arm-cyclists: recumbent- and kneeling handbike, adjusted for identified confounders. Furthermore, impairment type (categorized as i) muscle power/range of motion, ii) limb deficiency/leg length difference, and iii) coordination) and bike type were tested as effect modifiers.

RESULTS

POmean ranged from 303 ± 12 W for recumbent handcyclists to 482 ± 156 W for bicyclists. POmean was significantly related to time trial performance, for both leg-cyclists (β = 0.010, SE = 0.003, p < 0.01) and arm-cyclists (β = 0.029; SE = 0.005, p < 0.01), and impairment type and bike type were not found to be effect modifiers.

CONCLUSIONS

Sprint power was related to road time trial performance in all para-cyclists, with no differences found in this relation based on impairment type nor bike type. For those competing on a bicycle, tricycle, recumbent- or kneeling handbike, sprint tests might therefore be useful to predict or monitor time trial performance.

Kinesiotape on quadriceps and gluteus in counter movement jump and sprint in soccer players

BACKGROUND

Kinesiotape (KT) is a technique commonly used in sports practice. It may be beneficial in enhancing muscle function by additional cutaneous afferent stimulation. The objective of this study was to analyse the effect of KT on countermovement jump (CMJ) and 20-m sprints (sp) immediately and 24 h after its application on the quadriceps and gluteus maximus.

METHODS

37 male soccer players (19.7 ± 0.9 years old) were randomly assigned to one of 3 groups: experimental group: KT activation (KTact), placebo group: sham tape (KTst), and control group (CG). Participants performed a 30-min preliminary warm-up, after which they conducted CMJ and 20-m sp tests. These tests were repeated later (with KT application or not) and after 24 h.

RESULTS

Intergroup results found no significant differences either post-test (CMJ, p = 0.115; sp, p = 0.307) or after 24 h (p = 0.053). Intragroup results showed no significant results for CMJ, although 20-m sp seemed to display significant differences in the (KTst) (p = 0.002, post-hoc: 0.015 in pre_sp vs post_sp) and the (KTact) (0.021, in post-hoc: 0.007 in pre_sp vs post_sp), with a moderate effect in pre_sp vs post_sp (0.66) in the (KTact) after KT was applied.

CONCLUSION

KT application on the gluteus maximus and quadriceps in young soccer players increases the sprint execution time immediately and 24 h after application, even that the sprint execution time had not been grater that one tenth of the second (0.08 s). It also has no effect on CMJ.

Video-based biomechanical analysis of an unexpected Achilles tendon rupture in an Olympic sprinter

We used image-processing techniques to determine the moment (i.e., image frame) of the Achilles tendon (AT) rupture in an Olympic sprinter. This report may be unique due to the difficulty in conducting motion capture analyses during injury events. Our report includes one female Olympic sprinter, 29 years old (body mass: 56 kg, height: 1.68 m, and body mass index: 19.8 kg/m²) with a high-competitive profile history (2008 and 2012 Olympic Games participation; South American record holder in 100- and 200-m; Pan-American gold medalist in 200-m and 4 × 100-m relay) who suffered a complete AT rupture in the left leg while exercising in the final phase of rehabilitation following an Achilles tendinopathy in the contralateral limb. The greater dorsiflexion found at the moment of the injury and the delayed control of heel position indicated the presence of uncontrolled dorsiflexion, which potentially generated excessive eccentric stress over the tendon and, thus, the AT rupture. Here we discuss the relevance of lower leg alignment, the movements' characteristics, and the history of Achilles tendinopathy in the contralateral leg on the occurrence of the AT rupture.

Lower-body power, linear speed, and change-of-direction speed in Division I collegiate women's volleyball players

Volleyball players need to sprint and change direction during a match. Lower-body power, often measured by jump tests, could contribute to faster movements. How different jumps relate to linear and change-of-direction (COD) speed has not been analyzed in Division I (DI) collegiate women’s volleyball players. Fifteen female volleyball players completed the vertical jump (VJ), two-step approach jump (AppJ), and standing broad jump (SBJ). Peak power and power-to-body mass ratio (P:BM) were derived from VJ and AppJ height; relative SBJ was derived from SBJ distance. Linear speed was measured via a 20-m sprint (0–10 and 0–20 m intervals); COD speed was measured using the pro-agility shuttle. Pearson’s correlations (p < 0.05) calculated relationships between the power variables, and speed tests. There were no significant relationships between the power variables and the 0–10 m sprint interval. Greater VJ height (r = -0.534) and P:BM (r = -0.557) related to a faster 0–20 m sprint interval. This be due to a greater emphasis on the stretch-shortening cycle to generate speed over 20 m. However, although a 20-m sprint may provide a measure of general athleticism, the distance may not be specific to volleyball. This was also indicated as the AppJ did not relate to any of the speed tests. Nonetheless, VJ height and P:BM, and SBJ distance and relative SBJ, all negatively correlated with the proagility shuttle (r = -0.548 to -0.729). DI women’s collegiate volleyball players could develop absolute and relative power in the vertical and horizontal planes to enhance COD speed.

Body temperature and physical performance responses are not maintained at the time of pitch-entry when typical substitute-specific match-day practices are adopted before simulated soccer match-play

OBJECTIVES

To profile performance and physiological responses to typical patterns of match-day activity for second-half soccer substitutes.

DESIGN

Descriptive.

METHODS

Following a warm-up, 13 male team sports players underwent ∼85min of rest, punctuated with five min rewarm-ups at ∼25, ∼50, and ∼70min, before ∼30min of simulated soccer match-play. Countermovement jump performance (jump height, peak power output), alongside 15m sprints, were assessed post-warm-up, and pre- and post-simulated match-play. Core temperature, heart rate, ratings of perceived exertion, and blood glucose and lactate concentrations were measured throughout.

RESULTS

Warm-up-induced core temperature elevations (∼2.3%, +0.85°C; p<0.001) were maintained until after the first rewarm-up. Thereafter, core temperature was reduced from post-warm-up values until pre-simulated match-play (∼1.6%, -0.60°C; p<0.001), where values were similar to pre-warm-up (37.07±0.24°C, p=0.981). Simulated match-play increased core temperature progressively (p≤0.05) but values remained lower than post-warm-up (∼5min; p=0.002) until ∼10min into exercise. From post-warm-up to pre-simulated match-play, sprint times (∼3.9%, +0.10s, p=0.003), jump height (∼9.4%, -3.1cm; p=0.017), and peak power output (∼7.2%, -296W; p<0.001) worsened. Despite increased ratings of perceived exertion and elevated blood lactate concentrations (p≤0.05), sprint times were maintained throughout exercise, whereas peak power increased (∼7.8%, +294W; p=0.006) pre- to post-exercise.

CONCLUSIONS

At the point of simulated pitch-entry, body temperature and physical performance responses were not maintained from warm-up cessation despite typical substitute-specific match-day practices being employed in thermoneutral conditions. Evidence of performance-limiting fatigue was absent during ∼30min of simulated match-play. These data question the efficacy of practices typically implemented by substitutes before pitch-entry.

Foam rolling during a simulated half-time attenuates subsequent soccer-specific performance decrements

The passive nature of the half-time period with soccer/football can result in second-half performance decrements. As foam rolling (FR) can increase range of motion, neuromuscular efficiency, and enhance arterial function, the inclusion of FR during half-time may attenuate performance decrements. The objective of this acute study was to compare FR versus passive recovery during a simulated half-time period on simulated second-half soccer pass, sprint performance as well as quality of recovery. Thirteen male soccer players simulated a soccer match by performing two bouts of 15 × 20 m sprints with 30-s rest intervals. The bouts were separated by 10-min with either a passive recovery or they performed five FR exercises on both legs for 45-s each with 15-s rest. Tests were conducted before and following the simulated half-time period and consisted of Total Quality of Recovery (TQR), Loughborough Soccer Pass Test (LSPT), blood lactate (LAC), and sprint velocity of the simulated soccer match. Heart rates (HR) were recorded at the end of each test session and each sprint. Results showed no significant changes between conditions for TQR, LSPT, LAC and HR. However, while all sprint speed measures (mean, best of 15 sprints and mean of the first 5 sprints) significantly decreased with the passive condition, no decrement was noted with all sprint measures with the FR condition; there was only a significant (p = 0.001; d = 0.63) 2.1% decrease with the mean of the first 5 sprints. In conclusion, there is some evidence that FR may be beneficial to attenuate sprint speed impairments.

Change of direction asymmetry across different age categories in youth soccer

Background

In youth, the development of change of direction (COD) and sprint performance is a key component for successfully competing in soccer across age. During a COD, the presence of directional asymmetries may be detrimental due to the unpredictable nature of the sport. Therefore, the aims of the study were to investigate asymmetries in COD ability and to examine the differences in COD and sprint performance across age in young soccer players.

Methods

Sixty-eight sub-elite soccer players of different age categories (U18, U17, U16, U15) were tested on a 10-m linear sprint test and 90°COD (5-m entry and exit) test in both directions. Asymmetric index (AI) of COD deficit was obtained for dominant (fastest) and non-dominant directions (slowest).

Results

The results showed that U16 were more asymmetrical than U18, U17, and U15 from large to moderate effects. The sprint time improved linearly across age with U18 and U15 displaying the fastest and slowest 10-m sprint performance (p < 0.01), respectively. Moreover, COD ability measured by COD deficit did not change across age (p > 0.05).

Conclusion

Given the results of this study, practitioners are encouraged to assess asymmetries between dominant and non-dominant directions rather than solely players’ COD ability in young soccer players.

Changes in muscle activity during the flexion and extension phases of arm cycling as an effect of power output are muscle-specific

Arm cycling is commonly used in rehabilitation settings for individuals with motor impairments in an attempt to facilitate neural plasticity, potentially leading to enhanced motor function in the affected limb(s). Studies examining the neural control of arm cycling, however, typically cycle using a set cadence and power output. Given the importance of motor output intensity, typically represented by the amplitude of electromyographic (EMG) activity, on neural excitability, surprisingly little is known about how arm muscle activity is modulated using relative workloads. Thus, the objective of this study was to characterize arm muscle activity during arm cycling at different relative workloads. Participants (n = 11) first completed a 10-second maximal arm ergometry sprint to determine peak power output (PPO) followed by 11 randomized trials of 20-second arm cycling bouts ranging from 5–50% of PPO (5% increments) and a standard 25 W workload. All submaximal trials were completed at 60 rpm. Integrated EMG amplitude (iEMG) was assessed from the biceps brachii, brachioradialis, triceps brachii, flexor carpi radialis, extensor carpi radialis and anterior deltoid of the dominant arm. Arm cycling was separated into two phases, flexion and extension, relative to the elbow joint for all comparisons. As expected, iEMG amplitude increased during both phases of cycling for all muscles examined. With the exception of the triceps brachii and extensor carpi radialis, iEMG amplitudes differed between the flexion and extension phases. Finally, there was a linear relationship between iEMG amplitude and the %PPO for all muscles during both elbow flexion and extension.

Effect of skill-based training vs. small-sided games on physical performance improvement in young soccer players

Recently, there has been increasing attention to research related to the effect of skill-based or game-based training on soccer players’ physical performance. Therefore, this study aimed to compare the effectiveness of skill-based training (SBT) at maximum intensity versus the small-sided game (SSG) on the physical performance characteristics of young soccer players during the pre-season period. Twenty-two male soccer players (mean age 15.3 ± 3 years) were randomly assigned to either an SBT or SSG fully controlled intervention programme, running parallel for eight weeks and held twice a week. On three non-consecutive days before and after training players completed a test battery consisting of the 20 m sprint, T-run, countermovement jump, running anaerobic sprint test (RAST) and 20 m shuttle run. Data were analysed with a two-way ANOVA test for repeated measures. SBT and SSG interventions induced a significant improvement in the anaerobic power (10.9% vs 6.2%), explosive power (8.5% vs 5.6%), VO2max (6.7% vs 6.5%) and vertical jump (5.3% vs 2.9%), respectively. When the improvements in the physical performance variables of both groups are compared, the SBT group achieved greater improvement than the SSG group in anaerobic power (by 4.7%), in explosive power (by 2.8%), in vertical jumping (by 2.3%), in the 20 m sprint (by 2.2%) and T-test scores (by 1.7%). However, improvements in the VO2max were similar in both groups. The results of the present study suggest that SBT at maximum intensity may be more effective than SSG in improving the physical performance characteristics of young soccer players in the pre-competitive season.

The Functional Movement Screen total score and physical performance in elite male collegiate soccer players

The objectives of this study were to compare the differences in physical performance of elite male collegiate soccer players according to the Functional Movement Screen (FMS) total scores and to investigate the association between the FMS total score and physical performance. A total of 20 elite male collegiate soccer players (mean age, 19.6±0.7 years; height, 173.4±4.4 cm; body weight, 66.9±7.3 kg; and body mass index, 22.0±2.0 kg/m²) participated in the present study. The subjects were divided into two groups: the high FMS (FMS total score ≥14 points, n=10) and low FMS (FMS total score <14 points, n=10). All participants completed 10-m and 30-m sprint tests, the arrowhead agility test (right and left), and a coordination test. The statistical methods used to verify the study results were the independent sample t-test and Kendall’s Tau b correlation test. There were significant differences between the high and low FMS groups in the 10-m (P=0.014) and 30-m sprint (P=0.002) and arrowhead agility tests (right, P=0.039). Conversely, there were no significant differences in the arrowhead agility (left) and coordination tests between the two groups (P>0.05). Moreover, the FMS total score was found to have significant negative correlations with the 10-m sprint (r=−0.444, P=0.017), 30-m sprint (r=−0.425, P=0.016), and arrowhead agility tests (right, r=−0.389, P=0.023). These results suggest that higher FMS total scores could have a positive effect on the physical performance of the players.

The inter-unit and inter-model reliability of GNSS STATSports Apex and Viper units in measuring peak speed over 5, 10, 15, 20 and 30 meters

The objective of this investigation was to evaluate the inter-unit reliability (Apex vs. Apex; Viper vs. Viper) and inter-model reliability (Apex vs. Viper) from 5 to 30 m sprinting activity. Ten team sport players (age 22 ± 1 years) were enrolled in this crossover study and performed 1271 trials (436 Apex vs. Apex, 464 Viper vs. Viper, 371 Apex vs. Viper) consisting of 5–10 m, 10–15 m, 15–20 m, and 20–30 m sprints. Inter-unit reliability was calculated using the intra-class correlation coefficient (ICC) with 95% confidence interval (CI) and coefficient of variation (CV), while between-unit and model analysis were subsequently performed to evaluate differences in Vpeak. Apex (10 Hz) units had excellent inter-unit reliability for all distances, whereas Viper (10 Hz) units had good to excellent reliability. The CV was good (< 5%) for both GNSS models. Significant differences were found in Vpeak in Sprint 5–10 = 0.13 CI (0.08, 0.182) m^.s^-1, Sprint 10–15 = 0.06 CI (0.01, 0.1) m^.s^-1, and in Sprint overall = 0.06 CI (0.03, 0.09) m^.s^-1. Both Viper and Apex units can consistently report Vpeak measurements since good to excellent ICC and good CV were found. However, Vpeak measurements are significantly different between models for distances less than 15 m. In conclusion, this study shows that differences exist among manufacturers’ models and that the two GNSS models should not be used interchangeably to quantify Vpeak.

Improved maximal strength is not associated with improvements in sprint time or jump height in high-level female football players: a clusterrendomized controlled trial

Background

Maximal strength increments are reported to result in improvements in sprint speed and jump height in elite male football players. Although similar effects are expected in females, this is yet to be elucidated. The aim of this study was to examine the effect of maximal strength training on sprint speed and jump height in high-level female football players.

Methods

Two female football teams were team-cluster-randomized to a training group (TG) performing maximal strength training (MST) twice a week for 5 weeks, or control group (CG) doing their regular pre-season preparations. The MST consisted of 3–4 sets of 4–6 repetitions at ≥85% of 1 repetitions maximum (1RM) in a squat exercise. Sprint speed and jump height were assessed in 5-, 10- and 15 m sprints and a counter-movement jump (CMJ) test, respectively. Nineteen participants in TG (18.3 ± 2.7 years) and 14 in CG (18.3 ± 2.4 years) completed pre- and posttests and were carried forward for final analyses.

Results

There was no improvement in neither of the sprint times (p > 0.36), nor jump height (p = 0.87). The players increased their 1RM in squats (main of effect of time: p < 0.00, _pη² = 0.704), and an interaction effect of time x group was observed (p < 0.00, _pη² = 0.516) where the TG increased their 1RM more than the CT (between subjects effects: p < 0.001, _pη² = 0.965).

Conclusions

MST improved maximal strength in female football players to a large extent; however, the improvement in maximal strength did not result in any transference to sprint speed or jump height.

Trial registration

This study was registered at clinicaltrials.gov PRS (Protocol registration and results System) with the code NCT04048928, 07.08.2019, retrospectively registered.

Effects of different repeated sprint-training frequencies in youth soccer players

The aim of this study was to determine the effects of 2 different repeated-sprint ability (RSA) training frequencies (2 RSA sessions per week [RSA2D] or 1 RSA session [RSA1D]) under volume-equated conditions on sprint and RSA performance in under-15 (U15) soccer players. Twenty-seven youth male soccer players (age: 12.29±0.47 years; height: 158.35±10.86 cm; weight: 45.08±8.05 kg) were randomly assigned to RSA2D (n=14) or RSA1D (n=13) groups. The players performed the same RSA training for 6 weeks, and only the training frequency differed between the groups. Before and after the training period, 5 m sprint, 10 m sprint, 20 m sprint and the RSA test were assessed. No significant time × group interactions were observed (p>0.05). Within-group analysis showed significant improvements in 20 m sprint (p=0.046, partial eta squared [η _p ² ] = 0.150, large) and RSA average time (p=0.001, η _p ² =0.438, large), fastest time (p=0.012, η _p ² =0.229, large), and total time (p=0.001, η _p ² =0.438, large) from pre-test to post-test in RSA1D and RSA2D groups. However, no significant pre-post changes (p>0.05) were found in 5 m and 10 m sprint tests. In the between-group analysis, there were no significant differences between RSA1D and RSA2D groups in any variable. In conclusion, the current findings suggest that 6 weeks of RSA training 1 or 2 times per week in addition to typical soccer training produced significant and similar improvements in sprint and RSA performances. This information could be useful for coaches when planning training sessions during congested fixtures of soccer competitions or in periods when the emphasis should be placed on other physical qualities.

Effect of caffeinated gum on a battery of rugby-specific tests in trained university-standard male rugby union players

Background

Caffeine has been shown to enhance strength, power and endurance, characteristics that underpin performance in rugby. Caffeinated gum has attracted interest as a novel vehicle for delivering caffeine, because absorption of caffeine from gum is quick. Rapid absorption of caffeine may be useful during rugby matches when there is limited time for supplementation such as at half-time or when substitutes enter play. The purpose of this study was to determine whether a low dose of caffeine in gum improves performance in a battery of rugby-specific tests.

Methods

In a double-blind, randomized, placebo-controlled, crossover design, 17 male university-standard rugby players (mass: 85.6 ± 6.3 kg; height: 179.4 ± 6.2 cm; age: 20.4 ± 1.2 years) chewed caffeinated gum (200 mg caffeine) or a placebo gum on two occasions separated by a week. After a standardized warm-up, gum was chewed for 5 min. Subsequently, participants performed three countermovement jumps, followed by an Illinois agility test, 6 × 30 m repeated sprints, and the Yo-Yo IR-2 test; each test was separated by short rest periods.

Results

Caffeinated gum enhanced countermovement jump by 3.6% (caffeine: 43.7 ± 7.6 cm vs. placebo: 42.2 ± 6.2 cm; d = 0.22, 95% CI [0.006, 0.432]; p = 0.044). There was a greater resistance to fatigue during the 6 × 30 m repeated sprint test (fatigue index caffeine: 102.2 ± 0.9% vs. placebo: 103.3 ± 1.2%; d = 1.03, 95% CI [0.430, 1.613]; p = 0.001), and performance on the Yo-Yo IR2 was improved by 14.5% (caffeine: 426 ± 105 m, placebo: 372 ± 91 m; d = 0.55, 95% CI [0.130, 0.957]; p = 0.010). Caffeine gum had no significant effect on the Illinois agility test (caffeine 16.22 ± 1.08 s vs. placebo 15.88 ± 1.09 s; d = − 0.31, 95% CI [− 0.855, 0.240]; p = 0.271).

Conclusions

In university-standard rugby players, a low dose of caffeine (200 mg) supplied in chewing gum enhanced performance on the Yo-Yo IR-2 test and the countermovement jump test and reduced fatigue index during repeated sprints. These improvements in a battery of rugby-specific tests may transfer to enhanced performance in rugby matches.

Forelimb position affects facultative bipedal locomotion in lizards

Recent work indicates that bipedal posture in lizards is advantageous during obstacle negotiation. However, little is known about how bipedalism occurs beyond a lizard's acceleratory threshold. Furthermore, no study to date has examined the effects of forelimb position on the body center of mass (BCoM) in the context of bipedalism. This study quantified the frequency of bipedalism when sprinting with versus without an obstacle at 0.8 m from the start of a sprint. Forelimb positions were quantified during bipedal running at the start of a sprint and when crossing an obstacle. Two species with contrasting body forms (and thus different BCoM) were studied (Sceloporus woodi and Aspidoscelis sexlineata) to assess potential variation due to body plan and obstacle-crossing behavior. No significant difference in frequency of bipedalism was observed in S. woodi with or without an obstacle. However, A. sexlineata primarily used a bipedal posture when sprinting. Forelimb positions were variable in S. woodi and stereotyped in A. sexlineata Caudal extension of the forelimbs helped shift the BCoM posteriorly and transition to, or maintain, a bipedal posture in A. sexlineata, but not in S. woodi The posterior shift in BCoM, aided by more caudally placed forelimbs, helps raise the trunk from the ground, regardless of obstacle presence. The body plan, specifically the length of the trunk and tail, and forelimb position work together with acceleration to shift the BCoM posteriorly to transition to a bipedal posture. Thus, species exhibit morphological and behavioral adjustments to transition to and maintain facultative bipedalism while sprinting.

Over-the-counter performance enhancing mouthguards are unable to decrease blood lactate and improve power output during a Wingate anaerobic test (WAnT)

Background/Objective

Mouthguards are the primary mode of protection against maxillofacial injuries in contact sports, but recent research has also linked performance enhancement to this piece of equipment. The purpose of this study was to test the claims of the Under Armour ArmourBite (UAAB) mouthguard to decrease blood lactate concentration ([BL]) and increase power when compared to a generic over-the-counter mouthguard (OTC) and no mouthguard (NOMG) during an anaerobic performance test.

Methods

Seventeen recreationally active males (23.4 ± 2.7 years; 179.6 ± 7.4 cm; 83.0 ± 14.0 kg) were tested using the 30 s Wingate anaerobic test (WAnT) during three separate testing sessions.

Results

There were no differences in [BL] between any of the conditions immediately or 5 min posttest. There were also no differences in peak, relative or average power, or fatigue index during the WAnT. The UAAB mouthguard was therefore unsuccessful in improving anaerobic performance.

Conclusion

It is likely that more expensive, custom-fit dental mouthguards may be necessary for individuals to see any benefits to athletic performance.

Correlation of dynamic strength in the standing calf raise with sprinting performance in consecutive sections up to 30 meters

Sprinting represents a result-relevant task in many sports. The correlation of sprinting performance and one-repetition maximum (1RM) in a squat has been assumed as assured. Results of the correlation with 1RM of the plantar flexors are still pending. Assuming an increasing relevance of the reactive working capacity with increasing distance, a decrease of the influence of maximum strength of the calves is conceivable. We investigated the correlation of 1RM in a calf raise and sprint performance in consecutive sections up to 30 meters. The results showed medium to strong, very significant correlations (p < 0.01) for absolute (r = -0.483 to r = -0.720) and relative (r = -0.460 to -0.577) strength, whereas an increase of the correlation throughout the course is observed. The dynamic maximum strength of the calves is a basic prerequisite for short sprints and should be regarded as a performance reserve.

A comparison between the force-velocity relationships of unloaded and sled-resisted sprinting: single vs. multiple trial methods

PURPOSE

We sought to compare force-velocity relationships developed from unloaded sprinting acceleration to that compiled from multiple sled-resisted sprints.

METHODS

Twenty-seven mixed-code athletes performed six to seven maximal sprints, unloaded and towing a sled (20-120% of body-mass), while measured using a sports radar. Two methods were used to draw force-velocity relationships for each athlete: A multiple trial method compiling kinetic data using pre-determined friction coefficients and aerodynamic drag at maximum velocity from each sprint; and a validated single trial method plotting external force due to acceleration and aerodynamic drag and velocity throughout an acceleration phase of an unloaded sprint (only). Maximal theoretical force, velocity and power were determined from each force-velocity relationship and compared using regression analysis and absolute bias (± 90% confidence intervals), Pearson correlations and typical error of the estimate (TEE).

RESULTS

The average bias between the methods was between - 6.4 and - 0.4%. Power and maximal force showed strong correlations (r = 0.71 to 0.86), but large error (TEE = 0.53 to 0.71). Theoretical maximal velocity was nearly identical between the methods (r = 0.99), with little bias (- 0.04 to 0.00 m s^-1) and error (TEE = 0.12).

CONCLUSIONS

When horizontal force or power output is considered for a given speed, resisted sprinting is similar to its associated phase during an unloaded sprint acceleration [e.g. first steps (~ 3 m s^-1) = heavy resistance]. Error associated with increasing loading could be resultant of error, fatigue, or technique, and more research is needed. This research provides a basis for simplified assessment of optimal loading from a single unloaded sprint.

AGTR2 and sprint/power performance: a case-control replication study for rs11091046 polymorphism in two ethnicities

We aimed to replicate, in a specific athletic event cohort (only track and field) and in two different ethnicities (Japanese and East European, i.e. Russian and Polish), original findings showing the association of the angiotensin-II receptor type-2 gene (AGTR2) rs11091046 A>C polymorphism with athlete status. We compared genotypic frequencies of the AGTR2 rs11091046 polymorphism among 282 track and field sprint/power athletes (200 men and 82 women), including several national record holders and Olympic medallists (214 Japanese, 68 Russian and Polish), and 2024 control subjects (842 men and 1182 women) (804 Japanese, 1220 Russian and Polish). In men, a meta-analysis from the two combined cohorts showed a significantly higher frequency of the C allele in athletes than in controls (odds ratio: 1.62, P=0.008, heterogeneity index I²=0%). With regard to respective cohorts, C allele frequency was higher in Japanese male athletes than in controls (67.7% vs. 55.9%, P=0.022), but not in Russian/Polish male athletes (61.9% vs. 51.0%, P=0.172). In women, no significant results were obtained by meta-analysis for the two cohorts combination (P=0.850). The AC genotype frequency was significantly higher in Russian/Polish women athletes than in controls (69.2% vs. 42.1%, P=0.022), but not in Japanese women athletes (P=0.226). Our results, in contrast to previous findings, suggested by meta-analysis that the C allele of the AGTR2 rs11091046 polymorphism is associated with sprint/power track and field athlete status in men, but not in women.

Differences in hamstring activation characteristics between the acceleration and maximum-speed phases of sprinting

This study aimed to investigate activation characteristics of the biceps femoris long head (BFlh) and semitendinosus (ST) muscles during the acceleration and maximum-speed phases of sprinting. Lower-extremity kinematics and electromyographic (EMG) activities of the BFlh and ST muscles were examined during the acceleration sprint and maximum-speed sprint in 13 male sprinters during an overground sprinting. Differences in hamstring activation during each divided phases and in the hip and knee joint angles and torques at each time point of the sprinting gait cycle were determined between two sprints. During the early stance of the acceleration sprint, the hip extension torque was significantly greater than during the maximum-speed sprint, and the relative EMG activation of the BFlh muscle was significantly higher than that of the ST muscle. During the late stance and terminal mid-swing of maximum-speed sprint, the knee was more extended and a higher knee flexion moment was observed compared to the acceleration sprint, and the ST muscle showed higher activation than that of the BFlh. These results indicate that the functional demands of the medial and lateral hamstring muscles differ between two different sprint performances.

Time perception, pacing and exercise intensity: maximal exercise distorts the perception of time

INTRODUCTION

Currently there are no data examining the impact of exercise on the perception of time, which is surprising as optimal competitive performance is dependent on accurate pacing using knowledge of time elapsed.

METHODS

With institutional ethics approval, 12 recreationally active adult participants (f=7, m=5) undertook both 30s Wingate cycles and 20min (1200s) rowing ergometer bouts as short and long duration self-paced exercise trials, in each of three conditions on separate occasions: 1) light exertion: RPE 11, 2) heavy exertion: RPE 15, 3) maximal exertion: RPE 20. Participants were unaware of exercise duration and were required to verbally indicate when they perceived (subjective time) 1) 25%, 2) 50%, 3) 75% and 4) 100% of each bout's measured (chronological) time had elapsed.

RESULTS

In response to the Wingate task, there was no difference between durations of subjective time at the 25%, nor at the 50% interval. However, at the 75% and 100% intervals, the estimate for the RPE 20 condition was shortest (P<0.01). In response to rowing, there were no differences at the 25% interval, but there was some evidence that the RPE 20 condition was perceived shorter at 50%. At 75% and 100%, the RPE 20 condition was perceived to be shorter than both RPE 15 (P=0.04) and RPE 11 (P=0.008) conditions.

CONCLUSION

This study is the first to empirically demonstrate that exercise intensity distorts time perception, particularly during maximal exercise. Consequently external feedback of chronological time may be an important factor for athletes undertaking maximal effort tasks or competitions.

Effects of compression clothing on speed-power performance of elite Paralympic sprinters: a pilot study

Background

Compression garments are thought to aid performance in some selected speed–power activities owing to improved sensory feedback and proprioception. The aim of this study was to test the effects of using compression garments on speed and power-related performances in elite sprinters with visual impairment, who rely more on proprioception to perform than their Olympic peers. Eight top-level Paralympic sprinters competing in 100- and 200-m races performed, in the following order: unloaded squat jump (SJ), loaded jump squat (JS) and sprint tests over 20- and 70-m distances; using or not the compression garment. The maximum mean propulsive power value obtained during the JS attempts (starting at 40 % of their body mass, after which a load of 10 % of body mass was progressively added) was considered for data analysis purposes. The athletes executed the SJ and JS attempts without any help from their guides. Magnitude-based inference was used to analyze the results.

Findings

The unloaded SJ was possibly higher in the compression than the placebo condition (41.19 ± 5.09 vs. 39.49 ± 5.75 cm). Performance differences in the loaded JS and sprint tests were all rated as unclear.

Conclusions

It was concluded that the acute enhancement in vertical jump ability should be explored in the preparation of Paralympic sprinters during power-related training sessions. However, chronic effects in Paralympic athletes wearing compression garments need to be further tested, in order to support its use as a specific training aid.

ACTN3 R577X and ACE I/D gene variants influence performance in elite sprinters: a multi-cohort study

Background

To date, studies investigating the association between ACTN3 R577X and ACE I/D gene variants and elite sprint/power performance have been limited by small cohorts from mixed sport disciplines, without quantitative measures of performance. Aim: To examine the association between these variants and sprint time in elite athletes.

Methods

We collected a total of 555 best personal 100-, 200-, and 400-m times of 346 elite sprinters in a large cohort of elite Caucasian or African origin sprinters from 10 different countries. Sprinters were genotyped for ACTN3 R577X and ACE ID variants.

Results

On average, male Caucasian sprinters with the ACTN3 577RR or the ACE DD genotype had faster best 200-m sprint time than their 577XX (21.19 ± 0.53 s vs. 21.86 ± 0.54 s, p = 0.016) and ACE II (21.33 ± 0.56 vs. 21.93 ± 0.67 sec, p = 0.004) counterparts and only one case of ACE II, and no cases of ACTN3 577XX, had a faster 200-m time than the 2012 London Olympics qualifying (vs. 12 qualified sprinters with 577RR or 577RX genotype). Caucasian sprinters with the ACE DD genotype had faster best 400-m sprint time than their ACE II counterparts (46.94 ± 1.19 s vs. 48.50 ± 1.07 s, p = 0.003). Using genetic models we found that the ACTN3 577R allele and ACE D allele dominant model account for 0.92 % and 1.48 % of sprint time variance, respectively.

Conclusions

Despite sprint performance relying on many gene variants and environment, the % sprint time variance explained by ACE and ACTN3 is substantial at the elite level and might be the difference between a world record and only making the final.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2462-3) contains supplementary material, which is available to authorized users.

Sex differences in the effects of 12 weeks sprint interval training on body fat mass and the rates of fatty acid oxidation and VO2max during exercise

BACKGROUND

The purpose of this study was to examine whether very short duration, very high intensity sprint interval training (SIT) leads to loss of body fat mass in association with improvements to VO2max and fatty acid oxidation, and to assess the extent of sex dimorphism in these physiological responses.

METHODS

A total of 24 men and 17 women (mean (SEM) age: 39 (±2) years; body mass index 24.6 (0.6)) completed measurements of the maximal rate of oxygen uptake (VO2max) and fatty acid oxidation (FATmax). Body fat and lean mass were measured by dual emission x-ray absorptiometry, and fasting blood lipid, glucose and insulin profiles were assessed before and after training. SIT consisted of 4×20 s sprints on a cycle ergometer at approximately 175% VO2max, three times per week for 12 weeks.

RESULTS

Fat mass decreased by 1.0 kg, although men lost statistically significantly more fat than women both when expressed in Kg and as % body fat. VO2max increased by around 9%, but women improved VO2max significantly more than men. FATmax improved by around 13%, but fasting plasma glucose, insulin, total triglyceride, total cholesterol and high-density lipoprotein (HDL) did not change after training, while low-density lipoprotein decreased by 8% (p=0.028) and the HDL:Total Cholesterol ratio improved by 6%. There were no sex differences in these metabolic responses to training.

CONCLUSIONS

These results show lower body fat %, and higher rates of fatty acid oxidation and VO2max after 12 weeks of training for just 4 min per week. Notably, women improved VO2max more than men, while men lost more fat than women.

Influence of Active Recovery on Cardiovascular Function During Ice Hockey

Background

Ice hockey is a popular sport comprised of high-intensity repeated bouts of activity. Light activity, as opposed to passive rest, has been shown to improve power output in repeated sprinting and could potentially help to offset venous pooling, poor perfusion, and the risk of an ischemic event. The objective of our study was, thus, to examine the efficacy of low-intensity lower body activity following a simulated hockey shift for altering hemodynamic function.

Methods

In a cross-over design, 15 healthy hockey players (23 ± 1 years, 54 ± 3 mL/kg/min) performed two simulated hockey shifts. In both conditions, players skated up to 85 % of age-predicted heart rate maximum, followed by either passive recovery or active recovery while hemodynamic measures were tracked for up to 180 s of rest.

Results

Light active recovery within the confines of an ice hockey bench, while wearing skates and protective gear, was effective for augmenting cardiac output (an average of 2.5 ± 0.2 L/min, p = 0.03) at 45, 50, and 120 s. These alterations were driven by a sustained elevation in heart rate (12 bpm, p = 0.05) combined with a physiological relevant but non-significant (11.6 mL, p = 0.06) increase in stroke volume.

Conclusions

Standing and pacing between shifts offers a realistic in-game solution to help slow the precipitous drop in cardiac output (heart rate and stroke volume) that typically occurs with passive rest. Prolonging the duration of an elevated cardiac output further into recovery may be beneficial for promoting recovery of the working skeletal muscles and also avoiding venous pooling and reduced myocardial perfusion.

Key Points

Evidence that light activity in the form of standing/pacing is effective for maintaining cardiac output, and thus venous return

Increased cardiac output and venous return may help reduce the chances of poor perfusion (ischemia) and could also promote recovery for performance

This is a simple, low-risk, intervention demonstrated for the first time to work within the confines of a player’s bench while wearing hockey gear

Acute consumption of a caffeinated energy drink enhances aspects of performance in sprint swimmers

This study investigated the effect of a caffeinated energy drink on various aspects of performance in sprint swimmers. In a randomised and counterbalanced order, fourteen male sprint swimmers performed two acute experimental trials after the ingestion of a caffeinated energy drink (3 mg/kg) or after the ingestion of the same energy drink without caffeine (0 mg/kg; placebo). After 60 min of ingestion of the beverages, the swimmers performed a countermovement jump, a maximal handgrip test, a 50 m simulated competition and a 45 s swim at maximal intensity in a swim ergometer. A blood sample was withdrawn 1 min after the completion of the ergometer test. In comparison with the placebo drink, the intake of the caffeinated energy drink increased the height in the countermovement jump (49.4 (SD 5.3) v. 50.9 (SD 5.2) cm, respectively; P<0.05) and maximal force during the handgrip test with the right hand (481 (SD 49) v. 498 (SD 43) N; P<0.05). Furthermore, the caffeinated energy drink reduced the time needed to complete the 50 m simulated swimming competition (27.8 (SD 3.4) v. 27.5 (SD 3.2) s; P<0.05), and it increased peak power (273 (SD 55) v. 303 (SD 49) W; P <0.05) and blood lactate concentration (11.0 (SD 2.0) v. 11.7 (SD 2.1) mM; P<0.05) during the ergometer test. The caffeinated energy drink did not modify the prevalence of insomnia (7 v. 7%), muscle pain (36 v. 36%) or headache (0 v. 7%) during the hours following its ingestion (P>0.05). A caffeinated energy drink increased some aspects of swimming performance in competitive sprinters, whereas the side effects derived from the intake of this beverage were marginal at this dosage.

RasGAP mediates neuronal survival in Drosophila through direct regulation of Rab5-dependent endocytosis

The GTPase Ras can either promote or inhibit cell survival. Inactivating mutations in Drosophila RasGAP (encoded by vap), a Ras GTPase-activating protein, lead to age-related brain degeneration. Genetic interactions implicate the epidermal growth factor receptor (EGFR)-Ras pathway in promoting neurodegeneration but the mechanism is not known. Here, we show that the Src homology 2 (SH2) domains of RasGAP are essential for its neuroprotective function. By using affinity purification and mass spectrometry, we identify a complex containing RasGAP together with Sprint, which is a Ras effector and putative activator of the endocytic GTPase Rab5. Formation of the RasGAP-Sprint complex requires the SH2 domains of RasGAP and tyrosine phosphorylation of Sprint. RasGAP and Sprint colocalize with Rab5-positive early endosomes but not with Rab7-positive late endosomes. We demonstrate a key role for this interaction in neurodegeneration: mutation of Sprint (or Rab5) suppresses neuronal cell death caused by the loss of RasGAP. These results indicate that the long-term survival of adult neurons in Drosophila is crucially dependent on the activities of two GTPases, Ras and Rab5, regulated by the interplay of RasGAP and Sprint.