Re-examination of the post half-time reduction in soccer work-rate

Abstract

Objectives To re-examine the work-rate of soccer players immediately after a passive half-time interval with an alternative approach to data reduction and statistical contrasts.Design Time-motion analysis data (5Hz global positioning system), were collected from 20 elite youth players (age: 17±1 years) during 21 competitive league fixtures (5±3 matches per player).Methods Physical performances were categorised into total distance covered, total low-speed running (0-14.9kmh(-1)) and total high-speed running (15.0-35.0kmh(-1)). These dependent variables were subsequently time averaged into pre-determined periods of 5-, 15- and 45-min duration, and expressed in relative (mmin(-1)) terms to allow direct comparisons between match periods of different lengths. During the 15-min half-time interval players were passive (seated rest).Results There was a large reduction in relative total distance covered (effect size - standardised mean difference - 1.85), low-speed running (effect size -1.74) and high-speed running (effect size -1.37) during the opening 5-min phase of the second half (46-50min) when compared to the first half mean (0-45min). When comparing the 51-55 and 56-60-min periods, effect sizes were trivial for relative total distance covered (effect size -0.13; -0.04), low-speed running (effect size -0.10; -0.11) and small/trivial for high-speed running (-0.39; 0.11).Conclusions Using a more robust analytical approach, the findings of this study support and extend previous research demonstrating that players work-rate was markedly lower in the first 5-min after a passive half-time interval, although we observed this phenomenon to be transient in nature. Time-motion analysts might re-consider their data reduction methods and comparators to distinguish within-match player work-rate trends.