The purpose of this study was to investigate the long-term effects of high intensity resistance training on myosin heavy chain (MHC) isoform composition of single fibres. Muscle biopsies were obtained from the right vastus lateralis of eight bodybuilders (BB) and seven physical education students (PES). Histochemical analyses were used to determine the fibre type distribution and the fibre cross-sectional area. MHC isoform composition of single fibres was determined with protein electrophoresis. The percentage of fibres expressing MHC IIA and MHC I/IIA was larger in BB (P < 0.05), while MHC IIX was completely absent (P < 0.05). In contrast, myofibrilar ATPase histochemistry only revealed a significantly lower percentage of type IIX fibres in BB (P < 0.05). The muscle fibre profile in the vastus lateralis muscle of BB may represent an adaptation based on the mechanical and biochemical demands of the long-term resistance training.

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Performance in a volleyball match is the result of a dynamic and interactive process between two teams. The current study aimed to investigate the influence of the quality of opposition on skill performance indicators. A total of 550 teams’ performances (N = 550) from 275 sets of men’s European Championship 2019 was recorded and the effectiveness of 12 parameters from 5 basic volleyball skills was analyzed. A two-step cluster analysis was performed to divide 24 teams into three quality groups (upper, middle, lower) and 6 types of match status were created according to the quality of the opponents. Binomial logistic regression showed that for each type of match, the key performance factors that discriminate win and loss are differentiated, while the efficacy of attack win is associated with the success almost with all contexts studied. Other significant parameters were serve aces for matches between upper-quality teams, opponent’s errors for matches between teams of different quality and avoidance of blocked attacks for balanced matches. The findings emphasize the need for coaches to plan strategies that allow players with special serving abilities to risk for an ace, to enhance the side-out skills of their team and to work detailed on attack coverage systems.

Plyometric training has shown to improve vertical jump height, but the design and implementation of a plyometric training programme for adolescents requires consideration of several variables as well as the time of the season. The purpose of this study was to implement a pragmatic programme that improves vertical jump height, and to monitor the effects of a 15 week off-season plyometric and resistance training programme on the vertical jump height in adolescent female volleyball players. Ten adolescent female volleyball players (age: 15.1 ± 0.9 years, height: 1.71 ± 0.04 m, body mass: 63.6 ± 6.0 kg, volleyball training experience: 5.1 ± 1.4 years) underwent 15 weeks of plyometric and resistance training (twice and once a week, respectively). A single-targeted block periodised approach and a linear periodisation model were applied. Vertical jump height was assessed before the programme (T1), after 4 weeks (T2), after 12 weeks (T3) and at the end of the programme (T4). Jump height significantly increased by 8.8% over the full time of the investigation. No significant difference was found between T1 and T2 but for all other pairwise comparisons. Similarly, leg power was observed to increase by 6.5% (P = 0.001). The 15-weeks training programme showed to improve jump height and leg power. In consideration of its practical nature and its results in comparison with similar intervention studies, the programme suggests practical relevance for coaches.

The purpose of the present study was to investigate the deltoid muscle characteristics of wrestlers. Nine Greco-Roman competitive male wrestlers (mean age 20.1+/-2.7 yrs, height 175+/-0.6 cm, weight 83.2+/-12.5 kg, years of training 7.6+/-2.7 yrs) participated in this study. Six male healthy sedentary students (mean age 21.2+/-0.9 yrs, height 180+/-0.3 cm, weight 80.1+/-9.4 kg) served as controls. Muscle fibre distribution, cross-sectional area (CSA), as well as satellite cells, myonuclei and capillary density per muscle fibre area were determined by immunohistochemistry. Myosin heavy chain MHC isoform composition of single fibres was determined with protein electrophoresis. Immunohistochemical analysis showed that muscle fibre distribution of the MHC I and IIA were significantly higher in wrestlers than in controls (p<0.05). Electrophoretic analysis of single fibres revealed a significantly higher proportion of fibres containing MHC I and IIC in wrestlers (p<0.05). The mean CSA of type IIA fibres and the number of myonuclei per type II was significantly higher in wrestlers (p<0.05). We also found that the number of satellite cells was 2.5 fold higher in wrestlers than in the control group. This study suggests that the observed muscle fibre profile in the deltoid of wrestlers may represent an adaptation based on the specific mechanical and biochemical demands of the long-term training in Greco-Roman wrestling.