“…Fourteen studies (10,11,27,30,31,33,34,(36)(37)(38)(40)(41)(42)(43) investigated the influence of athletic training on measures of physical fitness and 15 studies (10, 11, 14, 15, 24-26, 28, 29, 32, 33, 35, 37, 39, 40) on parameters of stroke velocity. In terms of physical fitness, nine studies (10, 11,31,33,34,36,[40][41][42] examined lower-extremity muscle power and three studies (11,33,40) assessed upper-extremity muscle power. Five articles (10,11,31,34,41) analyzed tennisspecific endurance, eleven articles (11,27,30,33,34,(36)(37)(38)(41)(42)(43) investigated agility, nine studies (11,30,31,33,34,36,(40)(41)…”