Although we did not increase the training volume during the7-weeks period, as we used high-intensity plyometric exercises performed with maximal effort, an effective and safe training stimulus was applied during each plyometric session, as previously demonstrated in similar plyometric training interventions in young boys (Ramírez-Campillo et al., 2012) and soccer players (Ramírez-Campillo et al.,2014b; Thomas et al., 2009).