ORIGINAL ARTICLE

Energetics (and kinematics) of short shuttle runs Paola Zamparo1 · Francesca Bolomini1 · Francesca Nardello1 · Marco Beato1

Received: 23 October 2014 / Accepted: 29 April 2015 © Springer-Verlag Berlin Heidelberg 2015

Abstract Purposes The energy cost of shuttle running (CnetSR), over distances of 10–20 m, was reported to increase with the shuttle speed and to decrease with the shuttle distance. The aims of this study were to assess CnetSR over a shorter distance (5 m), at different speeds, and to estimate the energy cost based on a simple kinematic analysis (CnetK). Methods Ten subjects (six basketball players, BP; four non-basketball players, NBP) performed ten shuttle runs (SR) with 30 s of passive recovery in-between, over a distance of 5 + 5 m (with a 180° change of direction); these experiments were repeated at different speeds (range 2–3.5 m s−1). The values of average (vmean) and maximal (vmax) speed during each run were determined by means of 2 kinematic analysis and CnetK was calculated as: 0.96vmax . CnetSR was calculated based on data of oxygen uptake, blood lactate concentration and distance covered. Results The relationships between C (J m−1 kg−1) and v (m.s−1) are well described by CnetK (all subjects) = 11.76v − 13.09, R2 = 0.853; CnetSR (BP) = 11.94v − 12.82, R2 = 0.636; and CnetSR (NBP) = 14.09v − 14.53, R2 = 0.738. Hence CnetSR ≈ CnetK in BP, whereas CnetSR > CnetK in NBP (un-familiar with this specific motor task). Discussion The calculations proposed in this study allow to estimate C of short SR based on simple measures of vmax and can be utilized to develop training protocols in

Communicated by Peter Krustrup. * Paola Zamparo [email protected] 1

Department of Neurological and Movement Sciences, University of Verona, Verona, Italy

basketball as well as in other team sports (characterized by repeated sprints over short distances). Keywords Basketball · Shuttle test · Running economy · Intermittent exercise Abbreviations BCoM Body centre of mass BP Basketball players CnetLR Net energy cost of linear running (metabolic data) CnetSR Net energy cost of shuttle running (metabolic data) Cextbout The minimum energy cost of a SR (derived from kinematic analysis) CnetK Net energy cost of shuttle running (kinematic data): 2Cextbout d Shuttle distance E’O2bout Net energy expenditure during a shuttle run EK Kinetic energy EP Potential energy + Energy associated with positive external work Eext − Energy associated with negative external work Eext Eextbout Energy expenditure during a shuttle run (derived from kinematic analysis) HR Heart rate Lab Blood lactate concentration NBP Non-basketball players RER Respiratory exchange ratio SI Index of symmetry SR Shuttle run tbout Duration of one run/bout tex Exercise duration (=10tbout) ttot Total exercise duration (=tex plus the recovery periods)

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ttot/tex An index of the work to rest ratio tvmax Time needed to attain vmax vmean Average (horizontal) shuttle speed vmax Maximal (horizontal) shuttle speed V′O2 Oxygen uptake V′E Minute ventilation + Positive external work Wext − Negative external work Wext Wextbout External work during a shuttle run η+ Positive work efficiency η− Negative work efficiency

Introduction Only few (recent) studies report data of energy cost per unit distance (C) during shuttle running because the energy expenditure during a single shuttle run (SR) does not reach a steady state and thus cannot be easily determined (e.g. Zadro et al. 2011; Buglione and di Prampero 2013; Stevens et al. 2014; Zamparo et al. 2014). These investigations have shown that C increases with the shuttle speed and decreases with the shuttle distance. Buglione and di Prampero (2013) reported the following relationships between C (J m−1 kg−1) and v (range 2.86–4.30 m s−1) over the 10and 20-m distances in soccer players, runners and subjects practising various sport activities: C(10m) = 6.75v − 12.7, R2 = 0.870, N = 41; and C(20m) = 2.34v − 1.83, R2 = 0.824, N = 114. Over the 10-m distance, but at slower speeds (1.97–2.56 m s−1), Stevens et al. (2014) reported the following C vs. v relationship in amateur soccer players: C(10m) = 1.78v − 2.19, N = 14. Zamparo et al. (2014) reported values of C for shuttle runs over the 5-, 10- and 25-m distances in young basketball players but just at one, supra-maximal, speed (3.7, 4.5 and 5.1 m s−1, respectively); they also estimated the C vs. v relationship over the 5-m distance [C(5m) = 11.43v − 16.36] based on the equations reported by Buglione and di Prampero (2013). Therefore, to date, no values of C as a function of v are available in the literature for SR over distances