The effects of a recreational soccer program (RSP) upon body composition, heart rate variability (HRV), biochemical markers, cardio-respiratory fitness, and endothelial function in obese adolescents were investigated. A randomised controlled clinical trial was conducted with 30 adolescents aged 12-17 years and body mass index (BMI) >2 standard deviations of WHO reference values, which were assigned to RSP (n = 10, 2 girls) and obese control (n = 10, 4 girls) groups. The 12-week RSP included 60-min sessions performed 3 times/week. BMI, waist circumference, blood pressure, blood glucose, lipid profile, insulin, C-reactive protein, HRV, and maximal oxygen consumption (VO2peak) were evaluated following standardised procedures. Body composition was determined by dual-energy X-ray absorptiometry and endothelial function by venous occlusion plethysmography. After intervention, RSP exhibited significant reductions in BMI (-0.7 ± 0.2 kg · m(-2)), waist circumference (-8.2 ± 1.4 cm), %body fat (-2.2 ± 0.4%), systolic blood pressure (-5.0 ± 2.3 mmHg), total cholesterol (-16.2 ± 5.8 mg · dL(-1)), triglycerides (-20.5 ± 12.9 mg · dL(-1)), C-reactive protein (-0.06 ± 0.01 mg · dL(-1)), insulin resistance (HOMA-IR, -1.4 ± 0.6), and sympathetic activity (LF, -13.9 ± 6.6 un) vs. controls (P < 0.05). Significant increase was observed in parasympathetic activity (HF, 13.9 ± 6.6 un), VO2peak (7.9 ± 2.8 ml · kg(-1) · min(-1)), and high-density lipoprotein cholesterol (11.0 ± 6.3 mg · dL(-1)) (P < 0.05). Vascular conductance (19.5 ± 8.1 ml · min(-1) · 100 ml, P = 0.005) increased and vascular resistance (-5.9 ± 2.4 ml · min(-1) · 100 ml, P = 0.041) decreased in RSP, but not in controls. A 12-week recreational soccer intervention was effective to improve biochemical, cardiovascular, and fitness health markers in obese adolescents.

Although limited, results from controlled trials suggest that PA intervention may improve physical fitness and risk factors for cardiovascular disease in adolescents who are overweight or obese.

No abstract

This study aimed to analyse the short-term performance effects of three in-season low-volume strength-training programmes in college male soccer players. Fifty-seven male college soccer players (age: 20.3±1.6 years) were randomly assigned to a resistance-training group (n=12), plyometric training group (n=12), complex training group (n=12), or a control group (n=21). In the mid-season, players underwent a 9-week strength-training programme, with two 20 min training sessions per week. Short-term effects on strength, sprint, agility, and vertical jump abilities were measured. All training groups increased 1-RM squat (range, 17.2–24.2%), plantar flexion (29.1–39.6%), and knee extension (0.5–22.2%) strength compared with the control group (p<0.05). The resistance-training group increased concentric peak torque of the knee extensor muscles by 9.9–13.7%, and changes were greater compared with the control group (p<0.05). The complex training group presented major increments (11.7%) in eccentric peak torque of the knee flexor muscles on the non-dominant limb compared with the control group and plyometric training group (p<0.05). All training groups improved 20-m sprint performance by 4.6–6.2% (p<0.001) compared with the control group. No differences were observed in 5-m sprint and agility performances (p>0.05). Overall, the results suggest that in-season low-volume strength training is adequate for developing strength and speed in soccer players.

This study investigated the agreement and reliability of oxygen uptake (V̇O2), V̇O2 reserve (V̇O2 R), heart rate (HR) and power output at intensities corresponding to the gas exchange threshold (GET) and heart rate variability threshold (HRVT) during maximal cardiopulmonary exercise testing (CPET) in obese and eutrophic adolescents. A further aim was to establish whether the HRVT was able to detect changes in cardio-respiratory fitness in obese adolescents after 3 months of recreational soccer practice. First, 25 obese and 10 eutrophic adolescents (ages 12-17) visited the laboratory twice to perform cycling CPET to test the reliability of CPET outcomes at GET and HRVT. Furthermore, the level of agreement between GET and HRVT was determined for a subgroup of 10 obese adolescents after performing a 3-month recreational soccer program. No significant difference was found for V̇O2, %V̇O2 R, HR and power output at the GET and HRVT (P>0.05), which were equally able to detect improvements in aerobic fitness after the soccer intervention. Correlations between GET and HRVT for V̇O2 and %V̇O2 R ranged from 0.89 to 0.95 (P<0.001) and test-retest reliability ranged from 0.59 to 0.82 (P<0.006). Overall, HRVT seems to be a reliable alternative for prescribing aerobic exercise intensity in obese adolescents.

HRV indices calculated by Polar RS800cx and PPG appear to be as accurate and reproducible as data from ECG when evaluating the autonomic control of heart rate at rest in obese adolescents.

The purpose of this study was to check the validity and the intra- and inter-evaluators reproducibility of the Sargent Jump Test, as an instrument of explosive strength measurement of soccer players of the sub-15 class. Forty-five soccer players were randomly selected from different clubs competing in the local soccer championship. All subjects performed one test on the same jump platform model Jumptest® (Hidrofit Ltda, Brazil) and two independent Sargent Jump Tests assessed by the same evaluator. Two days later, another Sargent Jump Test was performed simultaneously assessed by 2 evaluators. In all tests, three jumps were performed and the highest one was registered. In order to check the validity, the first Sargent Jump Test results were compared to those from the jump platform, considered the gold standard. To evaluate intra- and inter-evaluator reproducibility, results from the first, second and third Sargent Jump Tests were analyzed. The validity and reproducibility were evaluated by intraclass correlation coefficients (ICC), and by the Bland and Altman test (statistical pack SPSS 11.0), with a significance level set at p<0.05. The values found for validity (r=0.99, p=0.001), for intra-evaluator reproducibility (r=0.99, p=0.001) and for inter-evaluator reproducibility (r=1.0, p=0.001), permitted us to conclude that the Sargent Jump Test is a valid and reproducible instrument for measuring the explosive strength in homogeneous groups, such as those used in the present study.

This study investigated the validity of determining the final work rates of cycling and walking ramp-incremented maximal cardiopulmonary exercise tests (CPETs) using a non-exercise model to predict maximal oxygen uptake VO2max and the American College of Sports Medicine ACSM's metabolic equations. The validity of using this methodology to elicit the recommended test duration of between 8 and 12 min was then evaluated. First, 83 subjects visited the laboratory once to perform a cycling (n=49) or walking (n=34) CPET to investigate the validity of the methodology. Second, 25 subjects (cycling group: n=13; walking group: n=12) performed a CPET on 2 separate days to test the reliability of CPET outcomes. Observed VO2max was 1.0 ml·kg(-1)·min(-1) lower than predicted in the cycling CPET (P=0.001) and 1.4 ml·kg(-1)·min(-1) lower in the walking CPET (P=0.001). Only one of the 133 conducted CPETs was outside the test duration range of 8-12 min. Test-retest reliability was high for all CPET outcomes, with intraclass correlation coefficients of 0.90 to 0.99. In conclusion, the non-exercise model is a valid and reliable method for establishing the final work rate of cycling and walking CPETs for eliciting test durations of between 8 and 12 min.