Multifactorial monitoring of training load in elite rugby sevens players: cortisol/cortisone ratio as a valid tool of training load monitoring.

The effectiveness of selected physiological and perceptual measures for monitoring training load and fatigue was studied in 16 male elite rugby sevens players during a 6-week intense training block (IT) and 2-week tapering (TAP). Daily training load (TL) and strain (TS) as well as weekly total score of fatigue (TSF) were quantified respectively by the session-rating of perceived exertion (RPE) method and an 8-item questionnaire. Also, testing was performed and 24 h urinary cortisol (C), cortisone (Cn), adrenaline (A) and noradrenalin (NA) excretion was measured before (T0) and after the IT (T1) and after the TAP (T2). The TL, TS and TSF increased during the IT and decreased during the TAP, in conjunction with a significant drop and improvement, respectively, of performance standards during the two periods. At T1, C and Cn levels increased while A and NA levels decreased, resulting in a higher C/Cn ratio and lower A/NA ratio, respectively. At T2, both C/Cn and A/NA returned to baseline values. The changes in C/Cn ratio, after the 6-week IT, were more closely related to mean TL, TS and TSF (r=0.75-0.76 vs. r=0.48-0.58, p<0.01) and to changes in the majority of performance measures than to A/NA ratio. Only the changes in C/Cn ratio after the 2-week TAP were related to mean TL, TS and TSF (r=0.61-0.68, p<0.01). The changes in hormone levels, training strain and performance standards reflected the physical and mental stressors of training, with complete recovery, as indicated by physiological homeostasis, achieved after an appropriate tapering period.

Reliability and criterion-related validity of a new repeated agility test.

The study aimed to assess the reliability and the criterion-related validity of a new repeated sprint T-test (RSTT) that includes intense multidirectional intermittent efforts. The RSTT consisted of 7 maximal repeated executions of the agility T-test with 25 s of passive recovery rest in between. Forty-five team sports players performed two RSTTs separated by 3 days to assess the reliability of best time (BT) and total time (TT) of the RSTT. The intra-class correlation coefficient analysis revealed a high relative reliability between test and retest for BT and TT (>0.90). The standard error of measurement (<0.50) showed that the RSTT has a good absolute reliability. The minimal detectable change values for BT and TT related to the RSTT were 0.09 s and 0.58 s, respectively. To check the criterion-related validity of the RSTT, players performed a repeated linear sprint (RLS) and a repeated sprint with changes of direction (RSCD). Significant correlations between the BT and TT of the RLS, RSCD and RSTT were observed (p<0.001). The RSTT is, therefore, a reliable and valid measure of the intermittent repeated sprint agility performance. As this ability is required in all team sports, it is suggested that team sports coaches, fitness coaches and sports scientists consider this test in their training follow-up.

Six-minute walking test predicts maximal fat oxidation in obese children.

BACKGROUND: Obesity is associated with reduced exercise maximal fat oxidation rate (FATmax), which is generally assessed by cardiopulmonary cycling test. The six-minute walking test (6MWT) presents an alternative method in patients. OBJECTIVE: The aim of this study was to establish a practical reference equation facilitating the prediction of FATmax from the 6 MWT in obese children of both genders. DESIGN: This study is a cross-sectional study using mixed linear and multiple regression models. RESEARCH METHODS AND PROCEDURES: Anthropometric measurements were recorded and submaximal cycling test and 6 MWT conducted for 131 school-aged obese children, 68 boys and 63 girls. A multiple regression analysis for FATmax, including six-minute walking distance (6 MWD), anthropometric and cardiac parameters as the dependent variables, was performed for the two genders separately. RESULTS: Mean 6 MWD and FATmax were 564.9 ± 53.7 m and 126.5 ± 12.1 mg min(-1) for boys and 506.7 ± 55.0 m and 120.7 ± 10.0 mg min(-1) for girls, respectively. The 6MWD, body mass index, Z-score, fat-free mass, waist and hip circumferences (WC and HC), rest heart rate, and systolic and diastolic blood pressures were highly correlated with FATmax for both genders. There was a significant correlation between 6 MWD and FATmax in both boys and girls (r = 0.88 and r = 0.81, P<0.001, respectively). Stepwise regression analyses revealed that the combinations of 6 MWD with HC for boys and 6MWD with WC for girls improved the predictability of the model (R(2) = 0.81 for boys and R(2) = 0.72 for girls; P<0.001). CONCLUSION: In obese children, the 6MWT can be used to predict FATmax when formal test of exercise capacity and gas exchange analysis are unavailable or impractical. It is therefore possible to prescript targeted exercises at FATmax, without performing indirect calorimetry, just from a field test.

Effect of an individualized physical training program on resting cortisol and growth hormone levels and fat oxidation during exercise in obese children.

OBJECTIVES: The aim of this study was to characterize the resting levels of cortisol and growth hormone (GH), and the substrate profile during exercise of obese children before and after an individualized training program. PATIENTS AND METHODS: Twenty-two obese children (13.1 ± 0.8 yrs) were included in the study. Twelve individuals (six boys and six girls; 31.1 ± 1.1 kg/m², VO2(peak)=1.92 ± 0.16l/min) participated in a two-month endurance training program and 10 individuals (five boys and five girls; 30.9 ± 1.7 kg/m², VO2(peak)=1.98 ± 0.12l/min) served as controls. Training was individualized and targeting at the point were fat oxidation was maximal (Lipox(max)). Substrate oxidation was evaluated by indirect calorimetry. To determine plasma cortisol and GH concentrations, blood was collected at rest before and after the two-month period. RESULTS: Before the program, no significant differences were detected between the training group and the control group for any of the measured anthropometric, metabolic or hormonal variables. At the end of the two-month program, training group showed an increase in VO2(peak) and fat oxidation during exercise. After the program, resting levels of GH and cortisol were significantly increased in the training group (+0.9 ± 0.3 ng/mL and +55.4 ± 10.3 ng/mL respectively, p < 0.01). Following the two-month period, there was no change in any variables measured in control group. CONCLUSION: The present data show that an individualized endurance training program targeting Lipox(max) improves fat oxidation during exercise and increases resting levels of GH and cortisol.

Exercise improves the ApoB/ApoA-I ratio, a marker of the metabolic syndrome in obese children.

AIM: This study was designed to examine the effect of training on components of the metabolic syndrome and ApoB/ApoA-I ratio in obese children. METHODS: We studied thirty-two obese children (13.3 ± 0.4 years) with 16 subjects who participated to 8-week training and 16 subjects serving as a control group. Training was individualized at the point where fat oxidation was maximal (Fat max). In each subject, pre- and postintervention anthropometric measures and biochemical tests on fasting blood were performed. RESULTS: After the programme, the training group showed an increase in VO(2peak) and fat oxidation during exercise. Body mass index (BMI), blood glucose and triglycerides were reduced, and high-density lipoprotein (HDL) was increased. ApoB/ApoA-I ratio decreased significantly (-0.43%, p < 0.01). Systolic and diastolic blood pressure also decreased (-8.4% and -10.9%, respectively). Among the training group, 10 subjects were classified as having the metabolic syndrome before the intervention and none after. No significant changes in any other variables were measured in the control group. CONCLUSIONS: Training targeted at Fat max reduces the prevalence of metabolic syndrome and its associated factors in obese children. In particular, this intervention decreases the ApoB/ApoA-I ratio, which may be considered as a marker for following this syndrome.

Effect of individualized weight-loss programmes on adiponectin, leptin and resistin levels in obese adolescent boys.

AIM: We investigate the effects of a 2-month weight-loss programme on plasma levels of adiponectin, leptin and resistin in obese adolescent boys. METHODS: Twenty-one obese adolescent boys (BMI = 30.8 +/- 3.2 kg/m(2)) completed the weight-loss programme including: 1/ either energy restriction (R), 2/ or individualized exercise training at the point of maximum lipid oxidation (Lipox(max)) (E), 3/ or energy restriction and training (RE). Body composition, lipid oxidation and plasma levels of adiponectin, leptin and resistin were measured before and after intervention. RESULTS: Following the weight-loss programme, adolescents of the RE group showed an improvement of their body composition (p < 0.01), an increase in plasma adiponectin (+73.7%, p < 0.01) and a decrease in plasma leptin (-38.8%, p < 0.01) leading to an increase in adiponectine/leptin ratio (ALR, +144.4%, p < 0.01) higher than the R or E groups. E and RE groups only showed a similar significant increase in plasma resistin (p < 0.05) and a significant improvement of lipid oxidation rate at Lipox(max) (p < 0.01 and p < 0.001). In addition, in RE group, ALR is correlated with waist/hip and waist/height ratios, resistin level, homoeostasis mode assessment (HOMA-IR) index and Lipox(max). CONCLUSION: In obese adolescents boys, moderate exercise training completed at Lipox(max) and combined with energy restriction improves their ability to oxidize lipids, which is associated with a normalization of their adiponectin, leptin and resistin levels resulting in an improved insulin sensitivity, as attested by a higher ALR and a lower HOMA-IR.

Two-month effects of individualized exercise training with or without caloric restriction on plasma adipocytokine levels in obese female adolescents.

OBJECTIVES: To examine if, in young obese patients, an individualized training programme in association with a caloric restriction programme which had an effect on whole-body lipid oxidation, was able to induce changes on plasma adipocytokine concentrations. MATERIALS AND METHODS: Twenty-seven obese female adolescents participated in the study. Whole-body lipid oxidation during exercise was assessed by indirect calorimetry during a graded cycle ergometer test. Body mass (BM), body mass index (BMI), percentage of body fat (%BF), insulin homeostasis model assessment (HOMA-IR) and fasting levels of circulating adipocytokines were assessed prior and after a two-month diet programme, individualized training programme targeted at Lipox(max) corresponded to the power at which the highest rate of lipids was oxidized and combined diet/training programme. RESULTS: The diet/training programme induced both a shift to a higher-power intensity of Lipox(max) (+27.8 + or - 5.1 W; p<0.01) and an increase of lipid oxidation at Lipox(max) (+96.8 + or - 16.2mg/min; p<0.01). The enhancement in lipid oxidation was significantly (p<0.01) correlated with the diet/training-induced improvement in %BF (r = -0.47), HOMA-IR (r = -0.66), leptin (r = -0.41), TNF-alpha (r = -0.48), IL-6 (r = -0.38), adiponectin (r = 0.43) and resistin (r = 0.51). CONCLUSION: This study showed that in obese female adolescents a moderate training protocol targeted at Lipox(max) and combined with a diet programme improved their ability to oxidize lipids during exercise, and that this improvement was associated with changes in plasma adipocytokine concentrations.