| Abstract |
Aim: The primary aim of the study was to examine the effects of three different seasonal soccer training programs in regard to strength training volume and load on sex steroids levels and exercise performance parameters in professional soccer players. Furthermore we examined any possible relationships between sex steroids and exercise performance responses. Our secondary aim was to examine the effects of the soccer detraining transition period just prior to the beginning of theabove seasonal intervention period on sex steroids and performance parameters. In addition, we evaluated throughout the study the responses of bone turnover markers, lipidemic profile, red blood cells, hematocrit and erythrocyte sedimentation rate. We also examined the effects of the detraining period on vitamin D levels, and its correlation with exercise performance parameters.
Design: Sixty-seven soccer players, members of three different professional teams (Team-A, n=23, height=79.1±1.3; Team-B, n=22, 182±2.3; Team-C, n=22, 181±1.4) participated in the study. Players were tested in four different occasions. The first testing was performed immediately after the end of the previous soccer season (1) followed by a second (2), third (3), and fourth (4) experimental testing after a six week detraining period, just prior the beginning of the pre-season period for the forthcoming soccer season, at the middle and immediately after the end of the soccer season (period 1). The period between testing 1 and 2 was characterized as the detraining transition period. During this period for the first two weeks of players abstained from any physical activity. The following four weeks, players performed low-intensity aerobic running three times per week. The periods between testing two and the end of the study was considered as the intervention period (period 2). The seasonal training programs during this period were expressed as high (Team-A), moderate (Team-B), and low (Team-C) strength-training stress according the strength training volume employed by each team. During the study, in each experimental period, blood samples were analyzed for total-testosterone, free-testosterone, and the metabolic product of activate testosterone 3 androstendiol glucuronade (3a-Diol-G), dehydroepiandrosterone-sulfate (DHEAS), Δ4-androstenedione, estradiol (E2), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin (PRL).
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Furthermore, the concentrations of total cholesterol (TC) high density lipoprotein (HDL), low density lipoprotein (LDL), apolipoprotein AI (apo-AI), apolipoprotein B100 (apo-B100)
, Lp(a), red blood cell count (RBC), hematocrit (Hct) and ERS were evaluated. Bone metabolism markers i.e. of C-terminal telopeptide (CTx), osteocalcin (OC), bone alkaline phosphatase (b-ALP), and C-terminal Propeptide of Collagen Type-I (CICP) were measured only at experimental sessions (1), (2), and (4). Furthermore, only in the detraining period vitamin D was measured. In addition, players were tested for maximal oxygen consumption (VO2max), squad-jump (SJ), countermovement-jump (CMJ), 10m and 20m sprint performance prior at the beginning of the pre-season period, at the middle (mid-point), and at the end of the competition period (end-point). Also anthropometric characteristics were measured (i.e. height, body weight [BW], body fat [BF], body mass index [BMI], waste to hip ratio[WHR]).
Results Analysis of our results revealed the following findings: (a) Detraining Period:No significant differences were observed for none of sex steroids, lipidemic profile paremers, RBC, Hct, and ERS at the end of the detraining period (p΄&γτ0.05). In contrast, in all teams exercise performance indices and bone formation markers decreased significantly (all p΄&λτ0.000), while significant increases were evident for CTX, vitamin D levels increased (all p΄&λτ0.000) and BW, BF, WHR, BMI (all p΄&λτ0.001) and vitamin levels (p΄&λτ0.000) in all experimental teams. Vitamin D correlated significantly with all exercise performance indices (all p΄&λτ0.000). No correlations were evident between sex steroids and androgens. (b) Intervention period: All performance parameters increased significantly until the midlle of the championsip in all teams (p΄&λτ0.001). However, performance was further increased only in Team-A for jumping and sprinting ability between end-point vs mid-point (p΄&λτ0.001). An effect of the training program of Team-A on TT levels was evident exhibiting significant differences between at all point-measurements (2/3:p=0.024, 2/4:p΄&λτ0.001, 3/4:p=0.008), while a marginally significant effect (p=0.051) was detected within Team-B and a non-significant effect in Team-C. Similar results were obtained for 3a-Diol-G in Team-A (p=0.001) where significant differences were found between end-point to both baseline (p=0.001) and mid-point (p=0.038).Despite these alterations no significant correlations were evident between these changes in the specific times points and exercise performance parameters. No differences were detectable for none
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of the rest sex steroids, parameters of the lipidemic profile, RBC, Hct, and ESR (p΄&γγτ0.05). In regard to bone metabolism, we observed significant increases in all bone formation markers (all p΄&λτ0.000) and a decrease in the bone resorption marker (CTX, p΄&λτ0.000) in team A at the end of the study compared to baseline. Similarly, weak significant increases in OC (P=0.038), b-alp (p=0.032), and CICP (p=0.045), and a reduction in CTX (p=0.039) were observed in team B at the end of the study compared to baseline, whereas no alterations were evident in team C. No significant correlations were evident between sex steroids and exercise performance indices, bone metabolism markers, blood lipids RBC, Hct, and ESR.
Conclusions. Our main finding is that the volume of strength training combined with soccer training caused an elevation of circulating TT and 3a-Diol-G levels in parallel to the induction of performance capacity, bone metabolism, and optimal body composition status. It is our opinion that the elevation of endogenous androgens as a result of the volume of strength training indicates that the only method to improve athletic performance is hard training. There are no substitutes or shortcuts. If the organism needs more androgens it will produce them endogenously. Furthermore, our findings indicate that a short term detraining period in soccer does not seem to affect sex steroid levels, but induce a rapid loss in optimal exercise performance capacity, body composition and bone metabolism adaptations to exercise. In regard, to lipidemic profile, RBC, Hct, and ERS our findings indicate that in chronically trained professional soccer players variation in training volume does not affect their levels. Finally, the soccer detraining period beneficially affects vitamin D as a result of both higher exposure to the sun but also reduced strength training stress. Notably, irrespective the level of performance this secosteroid is related to both aerobic and neuromuscular exercise capacity in soccer players.
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The effects of different seasonal training programs in the production of the adrenal and the gonadal sex hormones
