Riboli, A, Esposito, F, and Coratella, G. Small-sided games in elite football: practical solutions to replicate the 4-min match-derived maximal intensities. J Strength Cond Res 37(2): 366-374, ...2023-The purpose of the study was to determine the area per player (ApP, m 2 ·player -1 ) to replicate the maximal 4-min match-play period (4-min Peak ) using small-sided or large-sided games (SSGs) lasting the same duration in elite football players. Twenty players (age: 26 ± 5 years) competing in European championship and international UEFA competitions were monitored during SSGs with (SSG with ) or without (SSG without ) goalkeepers, both lasting 4-min. A total of 1,724 and 561 individual observations for SSG with and SSG without across 99 and 34 different SSGs formats were undertaken. Whole (90-min avg ) and 4-min Peak match demands were calculated. Relative (m·min -1 ) total, high-speed (HSRD), very high-speed (VHSRD), sprint, and acceleration/deceleration distance were collected. For both SSG with and SSG without , ApP was small -to- very-largely correlated with TD, HSRD, VHSRD, and sprint, whereas an inverse trivial -to- small correlation with acceleration/deceleration was found. In SSG with , the ApP to replicate 4-min Peak was larger ( p < 0.001, effect size ES: 0.33-5.80) than that to mimic 90-min avg for total distance, HSRD, VHSRD, and sprint, whereas for acceleration/deceleration the ApP was lower ( p < 0.001, ES: -3.13 to 0.48) for 4-min Peak . In SSG without , the ApP to replicate 4-min Peak was larger ( p < 0.001, ES: 0.04-3.72) than that to mimic 90-min avg for HSRD, VHSRD, and sprint. Some positional differences ( p < 0.05, ES: 0.22-1.10) in ApP were found. The ApP to replicate 4-min Peak was higher for SSG with than SSG without ( p < 0.001, ES: 0.67-3.58). These findings may help practitioners to recreate the 4-min Peak to manage ApP during SSGs in elite football.
Body composition is acknowledged as a determinant of athletic health and performance. Its assessment is crucial in evaluating the efficiency of a diet or aspects related to the nutritional status of ...the athlete. Despite the methods traditionally used to assess body composition, bioelectric impedance analysis (BIA) and bioelectric impedance vector analysis (BIVA) have recently gained attention in sports, as well as in a research context. Only until recently have specific regression equations and reference tolerance ellipses for athletes become available, while specific recommendations for measurement procedures still remain scarce. Therefore, the present narrative review summarizes the current literature regarding body composition analysis, with a special focus on BIA and BIVA. The use of specific technologies and sampling frequencies is described, and recommendations for the assessment of body composition in athletes are provided. Additionally, the estimation of body composition parameters (i.e., quantitative analysis) and the interpretation of the raw bioelectrical data (i.e., qualitative analysis) are examined, highlighting the innovations now available in athletes. Lastly, it should be noted that, up until 2020, the use of BIA and BIVA in athletes failed to provide accurate results due to unspecific equations and references; however, new perspectives are now unfolding for researchers and practitioners. In light of this, BIA and especially BIVA can be utilized to monitor the nutritional status and the seasonal changes in body composition in athletes, as well as provide accurate within- and between-athlete comparisons.
The present systematic review aimed to compare the accuracy of Bioelectrical Impedance Analysis (BIA) and Bioelectrical Impedance Vector Analysis (BIVA) vs. reference methods for the assessment of ...body composition in athletes. Studies were identified based on a systematic search of internationally electronic databases (PubMed and Scopus) and hand searching of the reference lists of the included studies. In total, 42 studies published between 1988 and 2021 were included. The methodological quality was assessed using the Quality Assessment Tool for Observational Cohort and Cross-sectional Studies as recommended by the National Institute of Health. Twenty-three studies had an overall good rating in terms of quality, while 13 were rated as fair and 6 as poor, resulting in a low to moderate risk of bias. Fat mass was inconsistently determined using BIA vs. the reference methods, regardless of the BIA-technology. When using the foot to hand technology with predictive equations for athletes, a good agreement between BIA and the reference methods was observed for fat-free mass, total body, intra and extra cellular water. However, an underestimation in fat-free mass and body fluids was found when using generalized predictive equations. Classic and
Specific
BIVA represented a valid approach for assessing body fluids (Classic BIVA) and percentage of fat mass (
Specific
BIVA). The present systematic review suggests that BIA and BIVA can be used for assessing body composition in athletes, provided that foot-to-hand technology, predictive equations, and BIVA references for athletes are used.
The aims of this study were (i) to investigate the criterion validity (vs. gold standard measurements) of the 10 and 18 Hz STATSports Apex units for measuring distances and peak speed (Vpeak) ...outcomes and (ii) to investigate the between-unit variability. Twenty university students were enrolled in the study (age 21 ± 2 years, weight 72 ± 6 kg, and height 1.76 ± 0.05 m). The criterion validity was tested by comparing the distances recorded by the units with ground truth reference (400-m trial, 128.5-m circuit, and 20-m trial). Vpeak values were compared with those determined by a gold standard criterion device (Stalker ATS Radar Gun) during a linear 20-m sprint. The distance biases for the Apex 10 Hz in the 400-m trial, 128.5-m circuit, and 20-m trial were 1.05 ± 0.87%, 2.3 ± 1.1%, and 1.11 ± 0.99%, respectively, while for the Apex 18 Hz the biases were 1.17 ± 0.73%, 2.11 ± 1.06%, and 1.15 ± 1.23%, respectively. Vpeak measured by the Apex 10 and 18 Hz were 26.5 ± 2.3 km h
and 26.5 ± 2.6 km h
, respectively, with the criterion method reporting 26.3 ± 2.4 km h
, with a bias of 2.36 ± 1.67% and 2.02 ± 1.24%, respectively. This study is the first to validate and compare the STATSports Apex 10 and 18 Hz. Between-analysis (
-test) for total distance and Vpeak reported non-significant differences. Apex units reported a small error of around 1-2% compared to the criterion distances during 400-m, 128.5-m circuit, 20-m trials, and Vpeak. In conclusion, both units could be used with confidence to measure these variables during training and match play.
Peripheral fatigue results from multiple electrochemical and mechanical events in the cell body and the muscle–tendon complex. Combined force and surface electromyographic signal analysis is among ...the most widely used approaches to describe the behaviour of a fatigued muscle. Advances in technologies and methodological procedures (e.g. laser diffraction,
31
P magnetic resonance spectroscopy, shear-wave elastography, tensiomyography, myotonometry, mechanomyography, and high-density surface electromyography) have expanded our knowledge of muscle behaviour before, during, and after a fatiguing task. This review gives an update on recent developments in technologies for investigating the effects of peripheral fatigue linked to skeletal muscle contraction and on mechanistic insights into the electrochemical and mechanical aspects of fatigue. The salient points from the literature analysis are: (1) the electrochemical and mechanical events in the cell (alterations in cross-bridge formation and function and in depolarization of the tubular membrane) precede the events taking place at the muscle–tendon complex (decrease in muscle–tendon unit stiffness); (2) the changes in the fatigued muscle are not homogenous along its length and width but rather reflect a functional compartmentalisation that counteracts the decline in performance; (3) fatigue induces changes in load sharing among adjacent/synergistic muscles. A focus of future studies is to observe how these regional differences occur within single muscle fibres. To do this, a combination of different approaches may yield new insights into the mechanisms underlying muscle fatigue and how the muscle counteracts fatigue.
Beato, M, Bianchi, M, Coratella, G, Merlini, M, and Drust, B. A single session of straight line and change-of-direction sprinting per week does not lead to different fitness improvements in elite ...young soccer players. J Strength Cond Res 36(2): 518-524, 2022-Effective prescription is especially important in elite soccer players, who have a very limited time to dedicate to specific physical development as a consequence of factors such as congested match schedules and travel. The aim of this study was to compare the effectiveness of one repeated-sprint training (RST) session per week over an 8-week period on physical performance. A second aim was to compare the effect of RST involving straight sprints (RST-SS) or changes of direction (RST-COD). This study used a randomized pre-post parallel group trial design. The elite soccer players were randomly assigned to either an RST-SS (10 players) or RST-COD (10 players). RST-SS was 3 sets of 7 × 30-m sprints with 20-second and 4-minute recovery between sprints and sets, respectively. RST-COD was 3 sets of 7 × 20 + 20 m (one COD of 180°) shuttle sprints with 20-second and 4-minute recovery between sprints and sets, respectively. The physical tests selected were long jump, repeated-sprint ability (RSA) best, RSA mean, 505 agility test, Yo-Yo recovery level 1, 10, 30, and 40 m sprints. RST-SS reported unclear variations in long jump, sprint 30 m, sprint 40 m, RSA best, and RSA mean, whereas RST-COD showed unclear and trivial variations in sprint 10 m, sprint 30 m, sprint 40 m, RSA best, and RSA mean. The between-group analysis did not report any statistical difference. In conclusion, a single session of RST-SS and RST-COD do not improve soccer-specific fitness indicators in elite youth players during the season.
Purpose
We investigated the effects of 12 weeks of passive static stretching training (PST) on force-generating capacity, passive stiffness, muscle architecture of plantarflexor muscles.
Methods
...Thirty healthy adults participated in the study. Fifteen participants (STR, 6 women, 9 men) underwent 12-week plantarflexor muscles PST (5 × 45 s-on/15 s-off) × 2exercises × 5times/week (duration: 2250 s/week), while 15 participants (CTRL, 6 women, 9 men) served as control (no PST). Range of motion (ROM), maximum passive resistive torque (PRT
max
),
triceps surae
architecture fascicle length, fascicle angle, and thickness, passive stiffness muscle–tendon complex (MTC) and muscle stiffness, and plantarflexors maximun force-generating capacity variables (maximum voluntary contraction, maximum muscle activation, rate of torque development, electromechanical delay) were calculated Pre, at the 6th (Wk6), and the 12th week (Wk12) of the protocol in both groups.
Results
Compared to Pre, STR ROM increased (
P
< 0.05) at Wk6 (8%) and Wk12 (23%). PRT
max
increased at Wk12 (30%,
P
< 0.05), while MTC stiffness decreased (16%,
P
< 0.05). Muscle stiffness decreased (
P
< 0.05) at Wk6 (11%) and Wk12 (16%). No changes in
triceps surae
architecture and plantarflexors maximum force-generating capacity variables were found in STR (
P
> 0.05). Percentage changes in ROM correlated with percentage changes in PRT
max
(
ρ
= 0.62,
P
= 0.01) and MTC stiffness (
ρ
= − 0.78,
P
= 0.001). In CTRL, no changes (
P
> 0.05) occurred in any variables at any time point.
Conclusion
The expected long-term PST-induced changes in ROM were associated with modifications in the whole passive mechanical properties of the ankle joint, while maximum force-generating capacity characteristics were preserved. 12 weeks of PST do not seem a sufficient stimulus to induce
triceps surae
architectural changes.
This study examined the most demanding passages of match play (MDP) and the effects of playing formation, ball-in-play (BiP) time and ball possession on the 1-min peak (1-min
) demand in elite ...soccer. During 18 official matches, 305 individual samples from 223 Italian Serie A soccer players were collected. MDP and 1-min
were calculated across playing position (central defenders, wide defenders, central midfielders, wide midfielders, wide forwards and forwards). Maximum relative (m·min
) total distance (TD), high-speed running (HSR), very high-speed running (VHSR), sprint (SPR), acceleration/deceleration (Acc/Dec), estimated metabolic power (P
) and high-metabolic load (HML) distance were calculated across different durations (1-5, 10, 90 min) using a rolling method. Additionally, 1-min
demand was compared across playing formation (3-4-1-2, 3-4-2-1, 3-5-2, 4-3-3, 4-4-2), BiP and ball/no-ball possession cycles. MDP showed large to verylarge effect-size (ES): 1.20/4.06 differences between 1-min
vs all durations for each parameter. In 1-min
, central midfielders and wide midfielders achieved greater TD and HSR (ES:0.43/1.13) while wide midfielders and wide forwards showed greater SPR and Acc/Dec (ES:0.30/1.15) than other positions. For VHSR, SPR and Acc/Dec 1-min
showed fourfold higher locomotor requirements than 90-min. 1-min
for Acc/Dec was highest in 4-3-3 for forwards, central and wide midfielders. 1-min
was lower during peak BiP (BiP
) for HSR, VHSR and Acc/Dec (ES: -2.57/-1.42). Comparing with vs without ball possession, BiP
was greater (ES: 0.06/1.48) in forwards and wide forwards and lower (ES: -2.12/-0.07) in central defenders and wide defenders. Positional differences in MDP, 1-min
and BiP
were observed. Soccer-specific drills should account for positional differences when conditioning players for the peak demands. This may help practitioners to bridge the training/match gap.
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