Procedure
The coaches and team managers from the four professional teams were invited to a four-hour instruction course that aimed to introduce the intervention programs. Before starting the intervention program, the coaches and club managers of the 4 groups were invited to an education course that was given by an experienced researcher which aimed to prescribe the warm-up intervention programs in detail (at the mid-season). All the coaches and participants of intervention groups received videos and illustrations of the 11 + program. All the training sessions were supervised and performed by the same study researcher to ensure their compliance with the programs. Verbal encouragement was given throughout the intervention period to motivate the players to concentrate on the quality of their exercise. All tests were conducted between 9:00 a.m. and 1:00 p.m.