The purpose of this study was to examine and compare the cardiorespiratory performance and isokinetic muscle strength between Greek soccer and basketball players of different divisions before starting the training season. Study participants included 100 soccer players and 61 basketball players, who were assigned according to the kind of sport and division. All participants underwent anthropometric measurements and performed an exercise test on a treadmill to determine maximal oxygen uptake (VO2max). Peak torque for quadriceps and hamstring muscles was measured on isokinetic dynamometer at angular velocity of 60 degrees/s(-1), 180 degrees/s(-1), and 300 degrees/s(-1). The statistical p value was set at p < 0.05. In soccer players VO2max in absolute and relative values was significantly lower in division IV compared to the other 3 divisions (3,413.4 +/- 351.0 vs. 3,932.7 +/- 551.2, 4,172.7 +/- 371.8, 4,223.0 +/- 323.8 ml x min(-1), respectively; p < 0.001 and 46.93 +/- 4.20 vs. 52.47 +/- 3.66, 54.86 +/- 3.80, 55.32 +/- 3.33 ml x kg x min(-1), respectively; p < 0.001). Basketball players presented significantly higher VO2max, in absolute values, compared to soccer players for divisions II (4,586.3 +/- 586.3 vs. 4,172.7 +/- 371.8 ml x min(-1); p < 0.05), III (4,319.6 +/- 418.6 vs. 3,932.7 +/- 551.2 ml x min(-1); p < 0.01), and IV (4,624.0 +/- 627.6 vs. 3,413.4 +/- 351.0 ml x min(-1); p < 0.001), respectively. Regarding peak torque, only basketball players showed significantly higher values at 60 degrees/sec(-1) in hamstrings for III (p < 0.05) and IV division (p < 0.05). Conclusively, the higher VO2max reached by professional soccer and basketball players compared to semiprofessional and amateur ones and between the soccer and basketball players of the same division can be attributed to the different duration of the maintenance period and to the effect of the training session on each sport, respectively. Finally, a higher level of muscle strength would be preferable in soccer and basketball and would reduce the risk for injuries in the maintenance and rebuilding training periods.

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.

The aim of the present study was to determine if 4 weeks of training cessation (detraining) followed by a 4-week strength training program can affect the isokinetic strength of elite youth soccer players. There were 13 players who participated in the study. The players performed anthropometric measurements and lower limb isokinetic strength measurements 3 times, before the training cessation, after the training cessation and after the 4-week strength training program. No significant differences were observed in the anthropometric and strength measurements (P>0.05) after the detraining period and after the training program (P>0.05). These results indicate that 4 weeks of detraining in elite youth soccer players does not have any significant effects according to their anthropometric characteristics and isokinetic strength of their lower limbs. Furthermore, neither the 4-week training program affected the parameters above. Perhaps, youth players can maintain the benefits of training better than adults due to their neural adaptations. The duration of the strength training program could be the reason of the lack of adaptations.

This study was conducted to determine if the acute: chronic workload ratio (ACWR) is related to the incidence of non-contact injuries. The purpose is to compare the external load of injured and non-injured soccer players with the same characteristics, such as position and age. The present analysis considers both the four and the two weeks preceding an injury. Physical characteristics were recorded and analyzed through global positioning systems (GPS) evaluation over one season of 24 competitive microcycles, 144 training sessions, and 32 matches in a total of 35 professional soccer players from the Greek Super League 1 and Super League 2. The loads calculated were total distance (TD), 15–20 km/h, 20–25 km/h, 25–30 km/h, accelerations (ACC) > 2.5 m/s2, and decelerations (DEC) > 2.5 m/s2). Nine injured athletes exceeded the critical threshold of an ACWR > 1.3 several times compared with non-injured athletes that did not reach this level. The present study showed that ACWR is related to a subsequent occurrence of injury but that the threshold of an ACWR can vary. This seems to be mainly influenced by assessing the load of the last two weeks compared with that of the four weeks before the injury.

Metaxas, T, Mandroukas, A, Michailidis, Y, Koutlianos, N, Christoulas, K, and Ekblom, B. Correlation of fiber-type composition and sprint performance in youth soccer players. J Strength Cond Res 33(10): 2629–2634, 2019—The aim of this study was to examine the correlation between muscle fiber type and sprint performance in elite young soccer players of different age groups of the same team. Twenty-eight young players participated in this study (group U15, n = 8; group U13, n = 9; and group U11, n = 11). Anthropometric assessments, acceleration (10 m), and Bangsbo modified sprint test (30 m) were performed. Muscle biopsies were obtained from the vastus lateralis, and after that, fiber-type composition was determined by immunohistochemistry. No significant correlations were found between the sprint test and muscle fiber distribution for the groups U13 and U11 (p > 0.05). Also, no correlations were found between cross-sectional areas in the types of fibers with the sprint test in all groups (p > 0.05). A positive correlation was found between type I fibers and the performance in the acceleration test (10 m) (r = 0.77, p < 0.05) was found only in group U15 and a negative correlation between type IIA fibers and the performance in the acceleration test (10 m) (r = −0.89, p < 0.05). The correlations were observed only in group U15, which may indicate that the duration and the intensity of the soccer systematic training can affect the plasticity of the muscle fibers. Specific soccer training in youth is one of the factors that can affect fiber-type plasticity. The specific training programs and status of U15 are more intensive, and the exercises are oriented more to improve physical fitness.