Peak match acceleration demands differentiate between elite youth and professional football players.

Youth footballers need to be developed to meet the technical, tactical, and physical demands of professional level competition, ensuring that the transition between competition levels is successful. To quantify the physical demands, peak match intensities have been measured across football competition tiers, with team formations and tactical approaches shown to influence these physical demands. To date, no research has directly compared the physical demands of elite youth and professional footballers from a single club utilising common formations and tactical approaches. The current study quantified the total match and peak match running demands of youth and professional footballers from a single Australian A-League club. GPS data were collected across a single season from both a professional (n = 19; total observations = 199; mean ± SD; 26.7 ± 4.0 years) and elite youth (n = 21; total observations = 59; 17.9 ± 1.3 years) team. Total match demands and peak match running demands (1-10 min) were quantified for measures of total distance, high-speed distance [>19.8 km·h-1] and average acceleration. Linear mixed models and effect sizes identified differences between competition levels. No differences existed between competition levels for any total match physical performance metric. Peak total and high-speed distances demands were similar between competitions for all moving average durations. Interestingly, peak average acceleration demands were lower (SMD = 0.63-0.69) in the youth players across all moving average durations. The data suggest that the development of acceleration and repeat effort capacities is crucial in youth players for them to transition into professional competition.

Positional and temporal differences in peak match running demands of elite football.

Temporal changes in the total running demands of professional football competition have been well documented, with absolute running demands decreasing in the second half. However, it is unclear whether the peak match running demands demonstrate a similar decline. A total of 508 GPS files were collected from 44 players, across 68 matches of the Australian A-League. GPS files were split into the 1st and 2nd half, with the peak running demands of each half quantified across 10 moving average durations (1-10 min) for three measures of running performance (total distance, high-speed distance [> 19.8 km · h-1] and average acceleration). Players were categorised based on positional groups: attacking midfielder (AM), central defender (CD), defensive midfielder (DM), striker (STR), wide defender (WD) and winger (WNG). Linear mixed models and effect sizes were used to identify differences between positional groups and halves. Peak running demands were lower in the second half for STR across all three reported metrics (ES = 0.60-0.84), with peak average acceleration lower in the second half for DM, WD and WNG (ES = 0.60-0.70). Irrespective of match half, AM covered greater peak total distances than CD, STR, WD and WIN (ES = 0.60-2.08). Peak high-speed distances were greater across both halves for WIN than CD, DM and STR (ES = 0.78-1.61). Finally, STR had lower peak average acceleration than all positional groups across both halves (ES = 0.60-1.12). These results may help evaluate implemented strategies that attempt to mitigate reductions in second half running performance and inform position specific training practices.

Temporal distribution of peak running demands relative to match minutes in elite football.

The peak match running demands of football (soccer) have been quantified across time durations of 1-10 min, however, little is known as to when the peak match running demands occur within match play. Data were collected from 44 elite footballers, across 68 fixtures (Files = 413, mean ± SD; 11 ± 8 observations per player, range; 1-33), with peak match running demands quantified for each playing half at ten incremental rolling average durations (1 min rolling averages, 2 min rolling averages, etc.). Data were assessed if players completed the full match. Three measures of running performance were assessed total distance (TD), high-speed distance (> 19.8 km · h-1) (HSD) and average acceleration (AveAcc)], with the in-game commencement time of the peak running demands recorded. Descriptive statistics and normality were calculated for each rolling average duration, with the self-containment of shorter rolling average epochs within longer epochs also assessed (e.g. Do the 1 min peak running demands occur within the 10 min peak running demands). Peak TD and AveAcc demands occurred early in each half (median time = 7-17 min and 6-16 min, respectively). Conversely, peak HSD covered was uniformly distributed (Skewness = 0-0.5, Kurtosis = 1.7-2.0). There were low-moderate levels of self-containment for each peak match running period (10-51%), dependent upon metric. Peak match running demands for TD and AveAcc occurred at similar stages of a match where TD and acceleration volumes are typically greatest, whereas peak HSD demands appeared more unpredictable. These timings may help inform training prescriptions in preparation of athletes for competition.

Between-match variation of peak match running intensities in elite football.

Peak match running intensities have recently been introduced to quantify the peak running demands of football competition, across incremental time intervals, to inform training practices. However, their between-match variation is yet to be comprehensively reported, limiting the ability to determine meaningful changes in peak match running intensities. The current study aimed to quantify the between-match variability in peak match running intensities across discrete moving average durations (1-10 min). GPS data were collected from 44 elite football players across 68 matches (mean ± SD; 13 ± 10 observations per player). For inclusion players must have completed 70mins of a match across a minimum of two matches. Performance metrics included total and high-speed (> 19.8 km · h-1) running distances and average acceleration (m · s-2), expressed relative to time. For each metric, the coefficient of variation and smallest worthwhile difference were calculated. The peak match running intensity data was similar to previously reported data from various football competitions. The between-match CV of relative total distance ranged between 6.8-7.3%, with the CV for average acceleration and relative high-speed running being 5.4-5.8% and 20.6-29.8%, respectively. The greater variability observed for relative high-speed running is likely reflective of the varying constraints and contextual factors that differ between matches. The reported between-match variability helps to provide context when interpreting match performance and prescribing training drills using peak match running intensity data.

Quantifying the Peak Physical Match-Play Demands of Professional Soccer Substitutes Following Pitch-Entry: Assessing Contextual Influences.

Purpose: To quantify the peak post-pitch-entry physical responses of soccer substitutes while assessing contextual influences. Peak responses may be important performance indicators for substitutes introduced to provide a physical impact. Method: Thirty-three professional substitutes wore Microelectromechanical Systems during 44 matches (4 ± 3 observations·player-1). Post-pitch-entry relative peak values for total and high-speed (> 5.5 m·s-1) distances, average acceleration, and PlayerLoad™ were calculated using rolling averages over 60-s to 600-s. Linear mixed models assessed contextual influences (position, substitution timing, scoreline, and location). Results: Substitutes introduced during the final ~15 min of match-play covered less high-speed distance than first-half substitutes (~2.8-3.1 m·min-1) over 480-s to 600-s epochs, and less than 60:00-74:59 min substitutes (~1.7-1.8 m·min-1) during 540-s and 600-s epochs. Average acceleration during all except 180-s epochs was lower for 75:00+ min substitutes compared with first-half replacements (~0.27-0.43 m·s-2), and lower than 60:00-74:59 min substitutes during 60-s (~0.13 m·s-2). Substitutes introduced when their team was winning recorded greater distances over 120-s to 600-s (~6.2-7.7 m·min-1), and higher PlayerLoad™ values during 120-s, 180-s, 300-s, and 480-s epochs (~2.7-3.6 arbitrary units·min-1), compared with when scores were level at pitch-entry. Irrespective of substitution timing, substitute midfielders exceeded the total distance of substitute attackers (~5.9-16.2 m·min-1) for all except 360-s and 600-s epochs, and defenders (~13.3-26.7 m·min-1) during epochs < 300-s. Conclusions: This study provides benchmark data for practitioners tailoring training and recovery protocols, particularly "top-up" conditioning, to the competitive demands of soccer substitutes. Knowing how contextual factors influence substitutes' peak match-play responses may help managers/coaches assess the efficacy of substitution strategies.

Acute Effects of Interset Rest Duration on Physiological and Perceptual Responses to Resistance Exercise in Hypoxia.

Lockhart, C, Scott, BR, Thoseby, B, and Dascombe, BJ. Acute effects of interset rest duration on physiological and perceptual responses to resistance exercise in hypoxia. J Strength Cond Res 34(8): 2241-2249, 2020-This study aimed to determine whether manipulating interset rest periods during resistance training in hypoxia impacts on physiological and perceptual responses to exercise. Twelve healthy males completed 1 repetition maximum (1RM) testing for the bilateral leg extension, before completing 4 separate randomized trials comprising 5 × 10 repetitions of leg extensions at 70% 1RM. Experimental trials were completed in both moderate hypoxia (FIO2 = 15%) and normoxia (FIO2 = 21%), using interset rest periods of both 60 and 180 seconds for each environmental condition. Near-infrared spectroscopy was used to quantify muscle oxygenation of vastus lateralis , and surface electromyography assessed the activation of vastus lateralis and medialis. Blood lactate concentration ([BLa]) and midthigh circumference were assessed before and immediately after each trial. Heart rate (HR) responses, blood oxygen saturation, and rating of perceived exertion (RPE) were also assessed after each set and the whole session RPE (sRPE). Perceived quadriceps soreness was reported before, immediately after, and at 24 and 48 hours after each trial. Muscle activation (sets 4-5), RPE (sets 3-5), and sRPE were significantly (p < 0.05) higher in the 60-second trials of the resistance exercise protocol. Significant increases (p < 0.01) were observed for [BLa] and midthigh circumference across sets within each condition. No significant main effect was observed for interset rest duration or environmental condition for muscle oxygenation, HR, or perceived quadriceps soreness. These findings indicate that performing resistance exercise in hypoxia or normoxia with shortened interset rest periods increases muscle activation and perceived exertion, without exacerbating muscle soreness.