High-intensity Actions in Elite Soccer: Current Status and Future Perspectives.

Over the years, soccer has become more physically demanding; the number and frequency of high-intensity actions have increased, and these activities are decisive in determining the match outcome. Importantly, the reductionist approach commonly used to analyze high-intensity actions does not contemplate a more contextualized perspective on soccer performance. Traditionally, most investigations have only provided quantitative data regarding sprints (i. e. time, distances, frequency) without examining "how" (e. g. type of trajectory or starting position) and "why" (e. g. tactical role) soccer players sprint. In fact, other high-intensity actions, apart from running, are not even mentioned (i. e. curve sprints, change of direction, and specific-jump tasks). This has led to the use of tests and interventions that do not accurately reflect real game actions. Given the true technical-tactical-physical demands of each playing position, this narrative review collected a wide-spectrum of current soccer-related articles and provided a discussion regarding high-intensity actions, with a positional-based approach. In this narrative review, practitioners are encouraged to contemplate and consider the different elements that characterize high-intensity actions in soccer, in order to assess and train soccer players under a more sport-specific and integrative perspective.

Unilateral Isometric Squat: Test Reliability, Interlimb Asymmetries, and Relationships With Limb Dominance.

ABSTRACT: Bishop, C, Read, P, Lake, J, Loturco, I, Dawes, J, Madruga, M, Romero-Rodrigues, D, Chavda, S, and Turner, A. Unilateral isometric squat: Test reliability, interlimb asymmetries, and relationships with limb dominance. J Strength Cond Res 35(2S): S144-S151, 2021-The aim of this study was to determine test reliability, establish interlimb asymmetries and their associations with force production capability on the dominant (D) and nondominant (ND) limbs during the unilateral isometric squat test. Twenty-eight recreational sport athletes attended a single-test session after familiarization and performed 3 trials on each limb with 140° of hip and knee flexion, to assess peak force (PF), rate of force development (RFD), and impulse at different time intervals. Reliability, interlimb asymmetries, and Pearson's r correlations were computed thereafter. Test reliability was metric-dependent with only PF showing good levels of reliability on both limbs (coefficient of variation = 5.44-5.70; intraclass correlation coefficient = 0.93-0.94). Interlimb asymmetries ranged from 8.36 to 25.46%, with a tendency for RFD and impulse asymmetries to reduce as time intervals increased. Three significant negative relationships of a possible 49 (r = -0.43 to -0.47; p < 0.05) were found between asymmetries and performance on the D limb. However, 31 significant negative correlations (r = -0.42 to -0.71; p < 0.05) were found between asymmetries and performance on the ND limb. These findings demonstrate that practitioners may only be able to use PF as a reliable test metric during a unilateral isometric strength test. Furthermore, the negative association between asymmetries and strength performance on the ND limb may indicate that the reduction of imbalances through targeted training interventions may be warranted.