Comparison the effect of two different volumes of concurrent training on some physical fitness factors, cortisol and hs-CRP serum level changes in adolescent soccer players

The purpose of present study was to compare the effect of two volumes six- and eight-week of concurrent training on physical fitness factors, cortisol, and high-sensitivity C-reactive protein (hs-CRP) level changes in adolescent soccer players. Twenty players (age: 15 ± 0.91 years; weight: 61.10 ± 10.07 kg; soccer experience: at least 5 years) randomly divided into 6-week or 8-week group (n=10). The training protocol had two phases including general (three weeks) and specific in three days a week for 90 min. The type and intensity were same for both groups and only the volume was different between them. Aerobic power (1609 m), speed (60 m), muscular endurance (push up and sit up), and fasted venous blood samples (cortisol and hs-CRP) were collected before and after training period at 8-8:45 P.M and 8-8:30 A.M, respectively. The values of VO2max, speed, push up, and sit up were improved compared to pre-training values in both groups. Eight-week volume was more effective regarding the reduction of cortisol (%16.77; P=0.033), but the speed of six-week group was improved (%5.27) with a large effect size (r = -0.11). With respect to other variables, there was no significant difference between the two groups. Gradual increase in intensity of conditioning training within eight weeks compared to the same increase within six weeks lead to more effective reduction in serum cortisol of adolescent soccer players, but in relation to hs-CRP levels and improve in VO2max, speed and muscular endurance, it has no more advantage.