Seasonal Variations in Performance and Asymmetry Data for Jump and Change of Direction Abilities in Female Soccer Players

ABSTRACT

Mainer-Pardos, E, Bishop, C, and Gonzalo-Skok, O. Seasonal variations in performance and asymmetry data for jump and change of direction abilities in female soccer players. J Strength Cond Res XX(X): 000-000, 2024-The study aimed to evaluate the progression of the percentage-based change of direction (COD) deficit (%CODD) over a competitive season, along with its correlation with performance tests and to examine the impact of the magnitude and direction of asymmetry at 4 stages of the season. Forty-seven (U-16, U-18, and U-20), highly trained, female soccer players performed unilateral vertical jumping (countermovement jump [CMJ]) and horizontal jumping (HJ), 10-m sprint, and 180° change of direction (COD180) tests. The %CODD was also calculated. Significant group and time effects (p < 0.05) were observed in CMJ, HJ, 10-m sprint, and COD180 tests, with U-20 players generally outperforming the U-18 and U-16 groups. Nonsignificant differences were reported in the %CODD between any time point or groups throughout the season. Moderate or large significant (r = 0.44-0.64; p < 0.05) relationships were found between %CODD and 10 m. The direction of asymmetry within and between tests at all time points was slight to moderate (k = -0.29 to 0.57). Notwithstanding, 51% of the players showed the best performance in the horizontal jump with the same leg throughout the season, whereas only 36% in %CODD. This study highlights the importance of developing strategies to improve %CODD depending on the player's position demands. Finally, individually monitoring the magnitude and direction of asymmetry can help practitioners monitor the effects of training and competition throughout the season.

"You Are Not Wrong About Getting Strong:" An Insight Into the Impact of Age Group and Level of Competition on Strength in Spanish Football Players

OBJECTIVE

This study aimed to compare the maximum and rapid force production of Spanish football players and explore the differences between age group and level of competition.

METHODS

A cross-sectional study was developed to evaluate the peak force (PF), relative PF, and rate of force development over 250 ms (RFD0-250) during the isometric midthigh pull between groups of football players based on age group (senior vs junior) and level of competition (national vs regional). Using a portable isometric rig, 111 football players performed 2 isometric midthigh-pull trials on a force plate. Two-way analysis of variance with Bonferroni post hoc correction was applied, and statistical significance was set at P ≤ .05. The PF, relative PF, and RFD0-250 0, 25, 50, 75, and 100 percentiles were also calculated and descriptively reported, separated by age group and level of competition.

RESULTS

The analysis of variance revealed a significant main effect of the level of competition for the PF (P < .001), relative PF (P = .003), and RFD0-250 (P < .001). There was a significant main effect of age group for the PF (P < .001). There was a significant interaction effect of the age group × level of competition for relative PF (P = .014). National players were stronger than regional players on the PF and RFD0-250 (P < .001). Senior players were stronger than junior players for the PF (P < .001).

CONCLUSIONS

Maximum and rapid force production are crucial for Spanish football players as they progress in both level of competition and age group. Practitioners should encourage young football players to prioritize strength development to improve their athletic performance.

Effects of 8 weeks pre-season training on physical fitness, heart rate variability and cognition in women soccer players

The aim of this study was to explore the variations (pre-post) of (i) Anthropometric measures: weight, body mass index, lean and muscle mass, (ii) Physical fitness: countermovement jump (CMJ) and VO2max, (iii) heart rate variability (HRV) (recumbent and sitting): mean RR, RMSSD, NN50 and NN50 %, (iv) Psychomotor Vigilance Task, and v) SART: ACC Go, ACC NoGo and reaction times in semi-professional women soccer players from the second division of the Spanish League. The analysis indicated that lean mass improved after the observation period (p = .05, d = -0.38), while no other significant changes in anthropometric measures were observed. Additionally, CMJ and aerobic power were also improved (p<.01, d>0.50). The RMSSD [recumbent (d = -0.73) and sitting (d = -0.52)] and NN50 [recumbent (d = -0.69) and sitting (d = -0.70)] increased after the period of observation (p < .05). Reaction time also significantly improved after the period of observation [PVT (d = 0.42) and SART (d = -0.89)]. Correlations performed between measures revealed that smaller body mass and body mass index were largely associated with greater NN50 (r < 0.83, p = .001). Additionally, greater CMJ and aerobic fitness were associated with greater HRV [recumbent (r = -51, p = .001) and sitting (r = -0.60, p = .01). The main findings of this study were that there was no relationship between cognitive performance and physical fitness, but HRV was related to body composition and physical fitness during the pre-season in women soccer players.

Rationale and Practical Recommendations for Testing Protocols in Female Soccer: A Narrative Review

ABSTRACT

Beato, M, Datson, N, Anderson, L, Brownlee, T, Coates, A, and Hulton, A. Rationale and practical recommendations for testing protocols in female soccer: A narrative review. J Strength Cond Res 37(9): 1912-1922, 2023-The aim of this narrative review is to evaluate the presented literature on tests (aerobic, speed, changes of direction [COD], strength, power, jump, and anthropometry) of the varied components of female soccer and to draw attention to the most suitable protocols to allow practitioners to accurately track players' fitness status. The 2 most common field tests used to assess aerobic fitness are the Yo-Yo intermittent test (level 1 and level 2) and the 30-15 intermittent fitness test because of an ability to measure multiple players at once with a soccer-specific intermittent profile. The sprinting performance can be assessed on distances of <30 m; however, longer distances (e.g., 40 m) allow for achieving peak speed (flying sprint test), which can be assessed using global navigation satellite system. Changes-of-direction capacity has been found to be an important component of players testing and training programs, although there is no "gold standard" to assess COD or repeated sprint ability performance in female players. Lower-limb power can be assessed using jump tests that can use force platforms, jump mats, and optoelectronic devices, while maintaining a good reliability. Several in-direct tests are currently available for assessing anthropometry parameters, such as skinfold thickness, hydrodensitometry, and ultrasound. However, dual-energy x-ray absorptiometry is the most valid and reliable method for assessing body composition in team sport athletes, with the addition of bone health that is a key measure in female athletes. In conclusion, the evidence reported in this review will be able to aid practitioners, coaches, and researchers to decide which tests meet the requirements of their environment.

Comparison of body composition components and anaerobic performance parameters of elite male motorcycle speedway riders between pre- and post-competitive season

The purpose of this study was to compare body composition components and anaerobic capacity indices in elite motorcycle speedway riders before and after the competitive season. This study included 12 volunteer male motorcycle speedway riders from the highest speedway league in Poland (PGE Speedway Ekstraliga) (age: 22.7 ± 6.0 years, body height: 171.3 ± 4.0 cm, body weight: 62.5 ± 3.1 kg). Before and after the competitive season, an assessment of body composition and Wingate test (WAnT) on a cycle ergometer with analysis of acute cardiorespiratory and biochemical responses was conducted. Sport level for all riders was defined by the number of heats won (WS), the total number of points scored in all heats including bonus points (PTS + B), and the percentage of heats won (%W). The motorcycle speedway riders participated in an average of 75.3 ± 15.0 total heats (HS) and obtained PTS + B equal 136.8 ± 48.2. The anaerobic performance, body composition, cardiorespiratory and biochemical responses did not changed after the competitive season. The significant statistical correlations were noted between the differences in the Fatigue Index during WAnT and total number of heats (r = -0.61) and with PTS + B (r = -0.58). Positively correlations were observed also between HS and differences: fat mass (FM) (r = 0.60) and percentage of fat mass (r = 0.61) (all p < 0.05). These findings reveal that the HS during the competitive season is related to the stabilization of anaerobic capacity in the WAnT. The HS is positively correlated with an increase in fat mass, and additional fat mass can adversely affect athletic performance in speedway.

Determining age-specific velocity thresholds for elite youth female soccer players

Purpose: This study aimed to establish age-specific velocity thresholds for Under (U)14 and U16 elite youth female soccer players. Methods: Data was collected using 10 Hz GPS units during 50 matches from 187 players (U14 n = 89; U16 n = 98). Spectral clustering identified velocity thresholds for high-speed running (HSR), very high-speed running (VHSR), and sprinting (SPR), for 699 half-match observations (U14 n = 369; U16 n = 330). Linear mixed modelling determined youth (U14 and U16) and age-group (U14 or U16) velocity thresholds, and compared distances covered between these and existing senior thresholds. The effect of playing position and playing half on velocity thresholds was also quantified. Results: Youth velocity thresholds of HSR (≥3.00 m·s^-1), VHSR (≥4.83 m·s^-1), and SPR (≥5.76 m·s^-1) were estimated from the model. Age-group and playing position influenced velocity thresholds but playing half did not. Adoption of youth and age-group velocity thresholds resulted in greater distance covered at HSR, VHSR, and SPR (p < 0.001; moderate-large effect size [ES] = 0.86-1.97) compared to senior thresholds. Both age-groups covered similar distances (trivial-small ESs = 0.002-0.23) when adopting youth and age-group velocity thresholds. Conclusion: These youth thresholds provide an alternative to arbitrary velocity thresholds within the literature, and thresholds derived from senior players or other populations, to inform appropriate quantification and interpretation of physical data within this population.

Reference values for performance test outcomes relevant to English female soccer players

The purpose of this study was to present reference standards for physical performance test outcomes relevant to elite female soccer players. We analysed mixed-longitudinal data (n = 1715 observations) from a sample of 479 elite youth and senior players as part of the English Football Association's national development programme (age range: 12.7 to 36.0 years). Semi-parametric generalized additive models for location, scale and shape (GAMLSS) estimated age-related reference centiles for 5-m sprinting, 30-m sprinting, countermovement jump (CMJ) height, and Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1) performance. The estimated reference centiles indicated that the median of the distribution of physical performance test scores varied non-linearly with advancing chronological age, improving until around 25 years for each performance variable. These are the first reference ranges for performance test outcomes in elite English female soccer players. These data can assist practitioners when interpreting physical test performance outcomes to track an individual's progress over time and support decision-making regarding player recruitment and development.

Seasonal Changes and Relationships in Training Loads, Neuromuscular Performance, and Recovery and Stress State in Competitive Female Soccer Players

Background: The purpose of this study was to examine seasonal changes in training load (TL), neuromuscular performance, subjective recovery, and stress state, and to investigate the relationships between acute and chronic TL and neuromuscular performance in competitive female soccer players.

Methods: Nine competitive female soccer players (20.0 ± 1.7 years; 60.3 ± 6.3 kg; 164.0 ± 5.8 cm) completed the Short Recovery and Stress Scale and the countermovement jump (CMJ) with polyvinyl chloride pipe (CMJ0) and 20 kg barbell (CMJ20) at 2–3 h before 1st match (NC₁), 6th match (NC₂), 9th match (C₁), and 15th match (C₂) of the competitive season. TL included total distance, high-speed running, and PlayerLoad. Acute and chronic TL was calculated by using the average of 2 days (D₂), 7 days (D₇), and 21 days (D₂₁) prior to four different match play.

Results: Significant decreases were found from NC₁ to C₁ in D₇ total distance [p = 0.03, Cohen's effect size (d_z) = 1.40]. D₇ total distance and PlayerLoad significantly decreased from NC to C₁ and C₂ (p = 0.001–0.01, d_z = 1.40–1.72). Significant increases were observed from NC₁ to C₁ in CMJ0 jump height (p = 0.03, d_z = 1.40), (p = 0.021, d_z = 1.44), and peak power (p = 0.03, d_z = 1.32). Significant negative correlations were observed for D₇ total distance and CMJ0 jump height (p = 0.02, r = 0.79) and peak power (p = 0.03, r = 0.71) at C₂, while significant positive correlations were observed at C₁ for D₇ PlayerLoad and CMJ0 jump height (p = 0.02, r = 0.80).

Conclusion: Polyvinyl chloride pipe (CMJ0) jump height and peak power may increase from preseason to the midcompetitive season. Seasonal variations may affect the relationships between D₇ TL and CMJ0 performance.

Effects of chronic betaine supplementation on performance in professional young soccer players during a competitive season: a double blind, randomized, placebo-controlled trial

OBJECTIVE

Various nutritional strategies are adopted for athletes to maintain and to improve performance during the competition season. Betaine may enhance performance during a competitive season by increasing the testosterone to cortisol ratio and reducing systemic inflammation. The aim of this study was to investigate the effect of betaine supplementation on the bio-motor abilities in young professional soccer players.

METHODS

Twenty-nine young professional soccer players (age, 15.5±0.3 years) were matched by position and randomly assigned to one of two groups for 14 weeks: betaine (BG, 2 g/day; n=14) or placebo (PG n=15). Diet was standardized by a nutritionist, and measures of muscular power (countermovement jump: CMJ), change of direction: modified 5-0-5), acceleration (10 m sprint), sprint performance (30 m sprint time: SpT), muscular strength (leg press and bench press one repetition maximum: 1-RM), repeated sprint ability (running-based anaerobic sprint test: RAST), and aerobic capacity (30-15 intermittent fitness test) were assessed in the pre (P1), mid (P2) and post (P3) season over the course of 5 days. All subjects participated in one soccer match and five training sessions per week.

RESULTS

Significant (p < 0.05) group x time interactions were found for maximal oxygen uptake (VO2max), anaerobic peak power, and muscular strength favoring BG at P2 and P3 compared to P1. There were meaningful (p < 0.05) group x time interactions for CMJ, SpT, and peak power during the RAST that favored the BG.

CONCLUSIONS

14-week of betaine supplementation increased predicted 1-RM, VO2max, and repeated sprint ability performance in youth professional soccer players. Betaine supplementation seems to be a useful nutritional strategy to improve and to maintain performance during a competitive soccer season.

Seasonal changes in the physical activity levels of youth Gaelic football players

This study quantified changes in physical activity (PA) levels attained by adolescents during Gaelic football (GF) participation across two time points in a season and determined if these changes affected their overall daily PA levels. A total of 130 adolescents (65 females;15.3 ± 1.5 years) wore an activPAL accelerometer to determine total moderate PA (MPA), vigorous PA (VPA) and moderate-to-vigorous PA (MVPA) during a seven-day measurement period, including during GF. The PA measurement was completed at "preseason" (T1) and "in-season" (T2) timepoints. Between T1 and T2, females significantly increased time spent in MVPA daily (p < 0.001, d = 0.95), on Gaelic football days (GFDs) (p = 0.036; d = 0.30), on non-Gaelic football days (NGFDs) (p < 0.001; d = 0.43), and during GF (p < 0.001, d = 0.90). Males did not record any significant changes in PA over time (p > 0.05). At T2, there were no significant differences in time spent in MVPA daily, on GFDs and NGFDs, and during GF between the genders (p > 0.05). The results suggest that the change in daily PA levels by females is a consequence of increased MVPA during GF and reduced PA barriers across the season.

Improved Carotid Elasticity but Altered Central Hemodynamics and Carotid Structure in Young Athletes

Young athletes most often exceed the physical activity recommendations of the World Health Organization. Therefore, they are of special interest for investigating cardiovascular adaptions to exercise. This study aimed to examine the arterial structure and function of young athletes 12-17 years old and compare these parameters to reference values of healthy cohorts. Carotid intima-media thickness (cIMT), carotid diameter, cIMT÷carotid diameter-ratio (cIDR), arterial compliance (AC), elastic modulus (Ep), β stiffness index (β), and carotid pulse wave velocity (PWVβ) were determined using ultrasound in 331 young athletes (77 girls; mean age, 14.6 ± 1.30 years). Central systolic blood pressure (cSBP) and aortic PWV (aPWV) were measured using the oscillometric device Mobil-O-Graph. Standard deviation scores (SDS) of all parameters were calculated according to German reference values. The 75th and 90th percentiles were defined as the threshold for elevated cIMT and arterial stiffness, respectively. Activity behavior was assessed with the MoMo physical activity questionnaire, and maximum power output with a standard cardiopulmonary exercise test. One-sample t-tests were performed to investigate the significant deviations in SDS values compared to the value "0". All subjects participated in competitive sports for at least 6 h per week (565.6 ± 206.0 min/week). Of the 331 young athletes, 135 (40.2%) had cIMT >75th percentile, 71 (21.5%) had cSBP >90th percentile, and 94 (28.4%) had aPWV>90th percentile. We observed higher cIMT SDS (p < 0.001), cIDR SDS (p = 0.009), and AC SDS (p < 0.001) but lower β SDS (p < 0.001), Ep SDS (p < 0.001), and PWVβ SDS (p < 0.001) compared to the reference cohort. The cSBP SDS (p < 0.001) and aPWV SDS (p < 0.001) were elevated. In conclusion, cIMT and cIDR were higher in young athletes than in a reference cohort. Furthermore, young athletes presented better carotid elasticity and lower arterial stiffness of the carotid artery. However, central arterial stiffness was higher compared to the reference cohort. The thickening of the carotid intima-media complex in combination with a reduction in arterial stiffness indicates a physiological adaptation to exercise in youth.

Analysis of Fitness Status Variations of Under-16 Soccer Players Over a Season and Their Relationships With Maturational Status and Training Load

The purposes of this study were (i) to analyze the variations in maximal oxygen consumption (VO_2max), maximal heart rate (HR_max), heart rate at rest, acceleration, maximal speed, agility, anaerobic sprint test (RAST) of peak power (RPP), RAST of minimum power, RAST of average power (RAP), and RAST of fatigue index (RFI) during the competitive season, using maturation status and accumulated training load as covariates, and (ii) to describe the differences between responders and non-responders in relation to baseline levels. Twenty-three elite players from the same team competing in the national under-16 competitions were evaluated for 20 weeks in period 1 (before league), middle (mid league), and period 2 (after league). The VO_2max (p = 0.009), maximal speed (p = 0.001), RPP (p < 0.001), RAP (p < 0.001), and RFI (p < 0.001) significantly changed across the assessment periods. Interestingly, using accumulated training load and maturation status as covariates revealed no statistical significance (p > 0.05). When analyzing responders and non-responders, only HR_max (between periods 1 and 2) showed no differences between the groups. As a conclusion, it can be seen that accumulated training load and maturation status play an important role in the differences observed across the season. Thus, coaches should consider the importance of these two factors to carefully interpret fitness changes in their players and possibly adjust training decisions according to the maturation level of the players.

Prediction of maturity offset and age at peak height velocity in a longitudinal series of boys and girls

BACKGROUND

Predicted maturity offset, defined as time before peak height velocity (PHV) is increasingly used as an indicator of maturity status in studies of physical activity, fitness, and sport.

OBJECTIVE

To validate maturity offset prediction equations in longitudinal samples of boys and girls.

METHODS

The original and modified maturity offset prediction equations were applied to serial data for 266 boys (8-17 years) and 147 girls (8-16 years) from the Cracow Growth Study. Actual age at PHV for each youngster was estimated with the SITAR protocol. In addition to maturity offset, the difference between CA at prediction and maturity offset provided an estimate of predicted age at PHV.

RESULTS

Predicted maturity offset and age at PHV increased, on average, with CA at prediction. Variation in predictions was reduced compared to that in observed ages at offset and at PHV, and was more apparent with the modified equations. Relatively few predicted ages at PHV approximated observed age at PHV in early and late maturing youth of both sexes; predictions were later than observed among the former, and earlier than observed among the latter.

CONCLUSION

Predicted maturity offset and ages at PHV with the original and modified equations increase with CA at prediction, have reduced variation, and have major limitations with early and late maturing boys and girls.

Contextual factors influencing the characteristics of female football players

Women's football participation rates are projected to increase to 60 million worldwide by 2026, doubling the current participation. Growing investment and the increase in research in women's football has had a positive effect on the level of performance over the last 10 years. The present review aimed to examine the literature on the physical and physiological characteristics of female football players from 2010 to 2019 to reflect the recent changes in professionalism. Characteristics investigated include anthropometry, strength, speed, endurance, power, change of direction and repeated sprint ability. These characteristics are presented in relation to playing position, age and competition-level. Results revealed that goalkeepers (171 cm, 66 kg) and defenders (168 cm, 61 kg) were the tallest and had the greatest body mass, while attackers were the fastest players over 20 m (3.05 s) and 30 m (4.38 s) and midfielders had the highest endurance (55.4 mL∙kg^-1∙min^-1) (P<0.05). Characteristics tended to improve with age until full biological maturity around 17 to 18 years of age. Competition comparisons demonstrated international players have significantly greater speed, repeated sprint ability, power and endurance characteristics (P<0.05). By identifying influential factors, coaches may be able to optimize their training and physical assessment practices, to better expose players to the required stimulus to develop these characteristics considered crucial to improved performance.

The Effect of a Single Session of Plyometric Training Per Week on Fitness Parameters in Professional Female Soccer Players: A Randomized Controlled Trial

Nonnato, A, Hulton, AT, Brownlee, TE, and Beato, M. The effect of a single session of plyometric training per week on fitness parameters in professional female soccer players. A randomized controlled trial. J Strength Cond Res XX(X): 000-000, 2020-As the interest and popularity of female soccer has increased over the last few decades, there still lacks research conducted with the elite population, specifically ecological training interventions during the competitive season. Therefore, the aim of this study was to compare the effectiveness of 12 weeks (undertaken once a week) of plyometric (PLY) training on physical performance in professional female soccer players during the season. Using a randomized controlled trial design, 16 players were included in the current study (mean ± SD; age 23 ± 4 years, weight 60.3 ± 4.9 kg, height 167 ± 3.7 cm) and randomized in PLY (n = 8) and Control groups (CON, n = 8), respectively. Squat jump (SJ), counter movement jump (CMJ), long jump (LJ), single-leg triple jump distance test (triple jump test), changes of direction 505 test (505-COD), and sprint 10 and 30 m were performed before and after 12 weeks of PLY training. Significant within-group differences were found in triple jump test dominant (p = 0.031, effect size [ES] = moderate) and nondominant limb (p = 0.021, ES = moderate) and sprint 10 m (p = 0.05, ES = large), whereas the CON did not report any positive variation. However, neither group reported significant variation in SJ, CMJ, LJ, 505-COD, and sprint 30 m (underlining the difficulties in obtain meaningful variation in season). These findings have strong practical applications because this study showed for the first time that a single session a week of plyometric training can significantly increase sport-specific fitness parameters in professional female soccer players during the season.