Training-induced changes in physical performance can be achieved without body mass reduction after eight week of strength and injury prevention oriented programme in volleyball female players

The purpose of the study was to analyse the changes in muscle strength, power, and somatic parameters in elite volleyball players after a specific pre-season training programme aimed at improving jumping and strength performance and injury prevention. Twelve junior female volleyball players participated in an 8-week training programme. Anthropometric characteristics, isokinetic peak torque (PT) single-joint knee flexion (H) and extension (Q) at 60 degrees/s and 180 degrees/s, counter movement jump (CMJ), squat jump (SJ), and reactive strength index (RSI) were measured before and after intervention. Significant moderate effects were found in flexor concentric PT at 60 degrees/s and at 180 degrees/s in the dominant leg (DL) (18.3 +/- 15.1%, likely; 17.8 +/- 11.2%, very likely) and in extensor concentric PT at 180 degrees/s (7.4%+/- 7.8%, very likely) in the DL. In the non-dominant leg (NL) significant moderate effects were found in flexor concentric PT at 60 degrees/s and at 180 degrees/s (13.7 +/- 11.3%, likely; 13.4 +/- 8.0%, very likely) and in extensor concentric PT at 180 degrees/s (10.7 +/- 11.5%, very likely). Small to moderate changes were observed for H/Q(CONV) in the DL at 60 degrees/s and 180 degrees/s (15.9 +/- 14.1%; 9.6 +/- 10.4%, both likely) and in the NL at 60 degrees/s (moderate change, 9.6 +/- 11.8%, likely), and small to moderate decreases were detected for H/Q(FUNC) at 180 degrees/s, in both the DL and NL (-7.0 +/- 8.3%, likely; -9.5 +/- 10.0%, likely). Training-induced changes in jumping performance were trivial (for RSI) to small (for CMJ and SJ). The applied pre-season training programme induced a number of positive changes in physical performance and risk of injury, despite a lack of changes in body mass and composition.