Quantifying volume and high-speed technical actions of professional soccer players using foot-mounted inertial measurement units

Abstract

Aims The aims of the study were two-fold: i) examine the validity and reliability of high-speed kicking actions using foot-mounted inertial measurement unit’s (IMU), ii) quantify soccer players within-microcycle and inter-positional differences in both the frequency and speed of technical actions. Methods During the in-season phase (25 weeks) of the UK domestic season, 21 professional soccer player ball releases, high-speed ball releases and ball release index were analysed. Pearson product-moment correlation coefficient and confidence intervals were used to determine the validity between the systems, whilst a general linear mixed model analysis approach was used to establish estimated marginal mean values for total ball releases, high-speed ball releases and ball release index. Results Good concurrent validity was observed for ball release velocity and high-speed kicks against a high-speed camera (r2- 0.96, CI 0.93–0.98). Ball releases, high-speed ball releases and ball release index all showed main effects for fixture proximity (p>0.001), playing positions (p>0.001) and across different training categories (p>0.001). The greatest high-speed ball releases were observed on a match-day (MD)+1 (17.6 ± 11.9; CI- 16.2 to 19) and MD-2 (16.8 ± 15; CI- 14.9 to 18.7), with MD+1 exhibiting the highest number of ball releases (161.1 ± 51.2; CI- 155.0 to 167.2) and ball release index (145.5 ± 45.2; CI- 140.1 to 150.9) across all fixture proximities. Possessions (0.3 ± 0.9; CI- 0.3 to 0.4) and small-sided games (1.4 ± 1.6; CI- 1.4 to 1.5), had the lowest values for high-speed ball releases with technical (6.1 ± 7.2; CI- 5.7 to 6.6) and tactical (10.0 ± 10.5; CI- 6.9 to 13.1) drills showing the largest high-speed ball releases. Conclusions The present study provides novel information regarding the quantification of technical actions of professional soccer players. Insights into absolute and relative frequency and intensity of releases in different drill types, provide practitioners with valuable information on technical outputs that can be manipulated during the process of planning training programmes to produce desired outcomes. Both volume and speed of ball release actions should be measured, when monitoring the technical actions in training according to fixture proximity, drill type and player position to permit enhanced training prescription.

Locomotor activities and subjective load differences between professional youth soccer players and professional development loans: A comparative analysis

“…MD-1, MD-5), playing position and training type (small sided game vs tactical drills) on the aforementioned technical parameters. Furthermore Lewis 29 observed MD + 1 having the highest absolute ball releases compared to all other training days, a decrease in frequency of ball releases as training becomes closer to match days, MD-1 and MD + 1 having the highest number of absolute and relative high-speed ball releases with variability being impacted by the type of drill or practice that the players were participating in. It thus is likely that different technical demands may be evident across different tiers of football and within different club settings.…”

“…Where there is reduced locomotor activity exposure, coaches lose the ability to provide 'top up' sessions within this hybrid loan system due to competing priorities for the primary and the host club. 29 To overcome such limitations, clubs in Spain use 'Colt' Squads or B teams to further the development opportunities of their transitioning players who represent their home club whilst playing in a lower division. 30 When comparing the professional progression of the players involved in the B team, Los Acros 17 showed that the players who had been signed internally from the club progressed at a rate of 43% versus 30% of players who were signed directly into the B squad.…”

“…It thus is likely that different technical demands may be evident across different tiers of football and within different club settings. 29 Additionally, our analysis only assessed one loan structure, it is likely that the format of loan agreement will also impact the locomotive demands of the player. Factors such as the league which loan clubs compete in, and the playing style of loan clubs, are also likely to influence locomotive demands and warrant further investigation.…”

“…Where there is reduced locomotor activity exposure, coaches lose the ability to provide ‘top up’ sessions within this hybrid loan system due to competing priorities for the primary and the host club. 29…”

“…Factors such as the league which loan clubs compete in, and the playing style of loan clubs, are also likely to influence locomotive demands and warrant further investigation. 29 Additionally, the structure of the loan, whether it be a traditional full-time loan or part-time development loan, will likely highly influence the weekly locomotor activity structure of training and match-play. Finally, the current study only compared data from one club with no inclusion of first team data, with a relatively low number in the development loan group, a system specific to Scotland.…”