Individual-based Creatine Kinase Reference Values in Response to Soccer Match-play.

The aim of the present study was to determine the creatine kinase reference limits for professional soccer players based on their own normal post-match response. The creatine kinase concentration was analyzed in response to official matches in 25 players throughout a 3-year period. Samples were obtained between 36-43 hours following 70 professional soccer matches and corresponded to 19.1±12.1 [range: 6-49] samples per player. Absolute reference limits were calculated as 2.5th and 97.5th percentile of the samples collected. Creatine kinase values were also represented as a percentage change from the individual's season mean and represented by 90th, 95th and 97.5th percentiles. The absolute reference limits for creatine kinase concentration calculated as 97.5th and 2.5th percentiles were 1480 U.L-1 and 115.8 U.L-1, respectively. The percentage change from the individual's season mean was 97.45±35.92% and players were in the 90th, 95th and 97.5th percentiles when the percentages of these differences were 50.01, 66.7, and 71.34% higher than player's season mean response, respectively. The data allowed us to determine whether the creatine kinase response is typical or if it is indicative of a higher than normal creatine kinase elevation and could be used as a practical guide for detection of muscle overload, following professional soccer match-play.

Effects of resistance exercise order on the number of repetitions performed to failure and perceived exertion in untrained young males.

Exercise order is an essential variable of resistance training (RT) programs which is usually related to repetition performance. The purpose of this study was to investigate the acute effect of different resistance exercise order on the number of repetitions performed to failure and related ratings of perceived exertion (RPE). Thirteen male adolescents (age: 14.46 ± 1.39 years, body height: 165.31 ± 12.75 cm, body mass: 58.73 ± 12.27 kg, estimated body fat: 21.32 ± 2.84%), without previous experience in RT, performed four resistance exercises: incline leg press (ILP), dumbbell lunge (DL), bench press (BP) and lying barbell triceps extension (TE) in two sequences - Sequence A (SEQA): ILP, DL, BP and TE; sequence B (SEQB): ILP, BP, DL and TE. The exercise sequences were performed in a randomized crossover design with a rest interval of 72h between sessions. Within-subjects analysis showed significant differences in the number of repetitions performed to failure in both sequences, but not in the RPE. Post-hoc tests revealed significant decrements in the number of repetitions from the first to the remaining exercises in both sequences. However, pairwise comparisons did not indicate significant differences between the same exercises performed in different sequences. In conclusion, the results of the current study in adolescents suggest that the main exercises should be performed at the beginning of the RT session.