Systematic Bias Between Running Speed and Metabolic Power Data in Elite Soccer Players: Influence of Drill Type

Gaudino P., Iaia F.M., Alberti G., Hawkins R.D., Strudwick A.J., Gregson W.

The aims of the present study were to:

i) evaluate the agreement between estimates of high-intensity activity during soccer small-sided games (SSGs) based on running speed alone and estimated metabolic power derived from a combination of running speed and acceleration;
ii) evaluate whether any bias between the two approaches is dependent upon playing position or drill characteristics.

Methods:

Three types of SSGs (5vs5, 7vs7, and 10vs10) were completed by 26 English Premier League outfield players. A total of 420 individual drill observations were collected over the in-season period using portable global positioning system technology. High-intensity activity was estimated using the total distance covered at speeds > 14.4 km·h⁻¹ (TS) and the equivalent metabolic power threshold of > 20 W·kg⁻¹ (TP). We selected 0.2 as the minimally important standardised difference between methods.

Results:

High-intensity demands were systematically higher (~100%, p < 0.001) when expressed as TP vs. TS irrespective of playing position and SSG. The magnitude of this difference increased as the size of SSG decreased (p < 0.01), with a difference of ~200% observed in the 5vs5 SSG. A greater difference between TP and TS was also evident in central defenders compared to other positions (p < 0.05), particularly during the 5vs5 SSG (~350%). Conclusion: We conclude that the high-intensity demands of SSGs in elite soccer players are systematically underestimated by running speed alone, particularly during “small” SSGs and especially for central defenders. Estimations of metabolic power provide a more valid estimation of the true demands of SSGs.

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