E Padua

Dose-response relationship of autonomic nervous system responses to individualized training impulse in marathon runners.

In athletes, exercise training induces autonomic nervous system (ANS) adaptations that could be used to monitor training status. However, the relationship between training and ANS in athletes has been investigated without regard for individual training loads. We tested the hypothesis that in long-distance athletes, changes in ANS parameters are dose-response related to individual volume/intensity training load and could predict athletic performance. A spectral analysis of heart rate (HR), systolic arterial pressure variability, and baroreflex sensitivity by the sequences technique was investigated in eight recreational athletes during a 6-mo training period culminating with a marathon. Individualized training load responses were monitored by a modified training impulse (TRIMP(i)) method, which was determined in each athlete using the individual HR and lactate profiling determined during a treadmill test. Monthly TRIMP(i) steadily increased during the training period. All the ANS parameters were significantly and very highly correlated to the dose of exercise with a second-order regression model (r(2) ranged from 0.90 to 0.99; P < 0.001). Variance, high-frequency oscillations of HR variability (HRV), and baroreflex sensitivity resembled a bell-shaped curve with a minimum at the highest TRIMP(i), whereas low-frequency oscillations of HR and systolic arterial pressure variability and the low frequency (LF)-to-high frequency ratio resembled an U-shaped curve with a maximum at the highest TRIMP(i). The LF component of HRV assessed at the last recording session was significantly and inversely correlated to the time needed to complete the nearing marathon. These results suggest that in recreational athletes, ANS adaptations to exercise training are dose related on an individual basis, showing a progressive shift toward a sympathetic predominance, and that LF oscillations in HRV at peak training load could predict athletic achievement in this athlete population.

Effect of recovery mode on repeated sprint ability in young basketball players.

The aim of this study was to examine the effect of recovery mode on repeated sprint ability in young basketball players. Sixteen basketball players (age, 16.8 ± 1.2 years; height, 181.3 ± 5.7 cm; body mass, 73 ± 10 kg; VO2max, 59.5 ± 7.9 mL·kg−1·min−1) performed in random order over 2 separate occasions 2 repeated sprint ability protocols consisting of 10 × 30-m shuttle run sprints with 30 seconds of passive or active (running at 50% of maximal aerobic speed) recovery. Results showed that fatigue index (FI) during the active protocol was significantly greater than in the passive condition (5.05 ± 2.4, and 3.39 ± 2.3, respectively, p < 0.001). No significant association was found between VO2peak and FI and sprint total time (TT) in either repeated sprint protocols. Blood lactate concentration at 3 minutes post exercise was not significantly different between the 2 recovery conditions. The results of this study show that during repeated sprinting, passive recovery enabled better performance, reducing fatigue. Consequently, the use of passive recovery is advisable during competition in order to limit fatigue as a consequence of repeated high intensity exercise.

Relation between maximal aerobic power and the ability to repeat sprints in young basketball players.

The aim of this study was to examine the effects of maximal aerobic power (&OV0622;O2peak) level on the ability to repeat sprints (calculated as performance decrement and total sprinting time) in young basketball players. Subjects were 18 junior, well-trained basketball players (age, 16.8 ± 1.2 years; height, 181.3 ± 5.7 cm; body mass, 73 ± 10 kg; &OV0622;O2peak, 59.6 ± 6.9 ml·kg−1·min−1). Match analysis and time-motion analysis of competitive basketball games was used to devise a basketball-specific repeated-sprint ability protocol consisting of ten 15-m shuttle run sprints with 30 s of passive recovery. Pre, post, and post plus 3-minute blood lactate concentrations were 2.5 = 0.7, 13.6 ± 3.1, and 14.2 ± 3.5 mmol·L−1, respectively. The mean fatigue index (FI) value was 3.4 ± 2.3% (range, 1.1–9.1%). No significant correlations were found between &OV0622;O2peak and either FI or total sprint time. A negative correlation (r = −0.75, p = 0.01) was found between first-sprint time and FI. The results of this study showed that &OV0622;O2peak is not a predictor of repeated-sprint ability in young basketball players. The high blood lactate concentrations found at the end of the repeated-sprint ability protocol suggest its use for building lactate tolerance in conditioned basketball players.

EFFECT OF WHOLE BODY VIBRATION TRAINING ON LOWER LIMB PERFORMANCE IN SELECTED HIGH-LEVEL BALLET STUDENTS

The aim of this study was to examine the effects of 8 weeks of whole body vibration (WBV) training on vertical jump ability (CMJ) and knee-extensor performance at selected external loads (50, 70, and 100 kg; leg-press exercise) in elite ballerinas. Twenty-two (age, 21.25 ± 1.5 years) full-time ballerinas were assigned randomly to the experimental (E, n = 11) and control (C, n = 11) groups. The experimental group was submitted to WBV training 3 times per week before ballet practice. During the training period, the E and C groups undertook the same amount of ballet practice. Posttraining CMJ performance significantly increased in E group (6.3 ± 3.8%, p ≤ 0.001). Furthermore, E group showed significant (p ≤ 0.05–0.001) post- training average leg-press power and velocity improvements at all the external loads considered. Consequently, the force-velocity and power-velocity relationship shifted to the right after WBV training in the E group. The results of the present study show that WBV training is an effective short-term training methodology for inducing improvements in knee-extensor explosiveness in elite ballerinas.

Morning Meal More Efficient for Fat Loss in a 3-Month Lifestyle Intervention

Objective: To evaluate the effects of 2 low-calorie diets but with different distributions of calories throughout the day on weight loss and other major obesity-related metabolic parameters. Methods: We randomly assigned 42 nonsmoking homemakers (age = 46.3 ± 2.3 years, body mass index [BMI] = 35.7 ± 0.8 kg/m2, mean ± SD) in 2 groups of 21 subjects (G1 and G2). The participants underwent a 3 month individualized Mediterranean-style diet (55% carbohydrate, 30% fat, 15% protein and fiber > 30 g), calorie (600 kcal daily deficit compared to the total energy expenditure measured by a metabolic Holter). Diets consisted of the same food and complied with cardiovascular disease prevention guidelines but differed in the distribution of calories throughout the day (G1: 70% breakfast, morning snack, lunch and 30% afternoon snack and dinner; G2: 55 breakfast, morning snack, lunch and 45% afternoon snack and dinner). Dual-energy X-ray absorptiometry was used for pre- and postintervention body composition assessment. Results: Thirty-six subjects completed the study (G1 = 18, G2 = 18). Both groups had significant improvements in body composition and metabolic parameters but G1 had enhanced results for weight loss (G1: −8.2 ± 3.0 kg; G2: −6.5 ± 3.4 kg; p = 0.028), waist circumference reduction (G1: −7 ± 0.6 cm; G2: −5 ± 0.3 cm; p = 0.033), and fat mass loss (G1: −6.8 ± 2.1 kg, G2: −4.5 ± 2.9 kg, p = 0.031; mean ± SD). Improvements were detected in both groups for blood pressure and blood and lipid parameters. G1 subjects showed a greater improvement in insulin sensitivity measured by homeostasis model assessment–estimated insulin resistance (G1: −1.37 ± 0.27, G2: −0.74 ± 0.12, p = 0.017). Conclusions: These data suggest that a low-calorie Mediterranean diet with a higher amount of calories in the first part of the day could establish a greater reduction in fat mass and improved insulin sensitivity than a typical daily diet.

Influence of the number of trials and the exercise to rest ratio in repeated sprint ability, with changes of direction and orientation.

Abstract Ruscello, B, Tozzo, N, Briotti, G, Padua, E, Ponzetti, F, and D’Ottavio, S. Influence of the number of trials and the exercise to rest ratio in repeated sprint ability, with changes of direction and orientation. J Strength Cond Res 27(7): 1904–1919, 2013—The purpose of this investigation was to determine if there were different trends in physical fatigue observed in 3 different sets, of 7 trials each, in repeated sprint training, performed in 3 different modes: straight sprinting over 30 m, shuttle sprinting over 15 + 15 m, and sprinting over 30 m with changes of direction. Recovery time among trials in the sets was administered according to the 1:5 exercise to rest ratio. The sets were performed on 3 different days, with at least 48 hours between each set. The study involved 17 trained male soccer players (height, 177.33 ± 6.21 cm; body mass, 71.63 ± 9.58 kg; body mass index, 23 ± 2.39 kg·m−2; age, 21.94 ± 3.58 years). To compare the different values of the time recorded, an index of fatigue was used. Significant differences among trials within each set (repeated measures analysis of variance; p < 0.05) and between the sets (factorial analysis of variance; p < 0.001) were found. Significant correlations between each test and countermovement jump and stiffness values recorded pre exercise were found (p < 0.05). Significant differences between countermovement jump and stiffness values recorded pre and post exercise were also found (p < 0.05). This study suggests that training sessions aimed at increasing the capacity of repeated sprint ability in nonlinear and multidirectional sprints (shuttle and change of direction), which might imply a different number of trials within the set or different exercise to rest ratios from the ones usually adopted for straight sprinting, to induce similar trends of fatigue. As practical applications, the estimated numbers of necessary trials in the different sets and the possible exercise to rest ratios, resulting from mathematical modeling, are provided for each investigated sprinting mode.

Exercise individualized by TRIMPi method reduces arterial stiffness in early onset type 2 diabetic patients: A randomized controlled trial with aerobic interval training

BACKGROUND Arterial stiffness (AS) and baroreflex sensitivity (BRS) are subclinical markers of vascular diseases in type 2 diabetes (T2D). We evaluated the effects of aerobic interval training (AIT), with loads prescribed according to individual heart rate and lactate profiling obtained during a baseline treadmill test (TRIMPi method), on AS and BRS in patients with early-onset T2D without cardiovascular complications. POPULATION STUDY AND METHODS Twenty-two sedentary overweight T2D patients (aged 57±7years) were randomized to 12-weeks open-label of supervised AIT by TRIMPi (n=8) or unsupervised physical activity as per usual care (SOC) (n=11). Following parameters were evaluated (pre- and post-): anthropometrics; six-minute walking test (6MWT); fasting glucose, insulin, HbA1c; Pulse Wave Velocity (PWV) and Augmentation Index (AIxHR75) using radial approach (SphigmoCor System); BRS using Finapress method. RESULTS Both interventions significantly improved distance walked during 6MWT (AIT 52±21m; SOC 39±24m, p<0.001 for both). PWV significantly improved with AIT (p<0.001) whereas did not vary with SOC (p=0.47). Similar trend was observed for AIxHR75. Resulting percent changes from baseline were significantly better for AIT vs SOC, in both PWV (-15.8±2.1 vs +1.50±3.4%, p<0.001) and AIxHR75 (-28.9±3.2% vs +12.7±2.4%, p<0.001). BRS similarly improved in both groups (p<0.001 for both), as well as body weight, HbA1c and blood pressure. CONCLUSION In sedentary T2D patients, 12-weeks AIT individualized by TRIMPi method improved AS to a greater extent than usual recommendation on physical activity, whilst exerting comparable effects on exercise capacity, glycemic control and body weight. Further researches are needed to ascertain durability of these effects.

The efficacy of plantar stimulation on human balance control.

Abstract Aim: The aim of this study was to evaluate the body sway using firm, foam, and firm textured surfaces on 17 young adults. Method: Displacement of center of pressure (CoP), anteroposterior velocity (VA/P), and mediolateral velocity (VM/L) were measured. Data: The data showed a significant decrease of CoP, VA/P, and VM/L between support surfaces and vision. Results: The results showed that, differently from the firm and foam, the textured surface is able to increase the plantar feedback to maintaining postural control.

Acute changes in neuromuscular activity in vertical jump and flexibility after exposure to whole body vibration

Abstract This study was aimed to investigate the neuromuscular activity after 10 minutes of exposure to a whole body vibration (WBV) session. Twenty male young adults (24.8 ± 2.5 year olds) were randomized and divided into 2 groups: the vibration group (VG) was exposed to 10 minutes of WBV at 35 Hz; performed 10 minutes of WBV at 35 Hz (displacement = 5 mm; magnitude = 5 g); the nonvibrated group (NVG) was the placebo group that maintained the same position on the plate but without exposure to any type of vibration. Subjects were evaluated with counter movement jump (CMJ) and muscular flexibility by means of electromyographic (EMG) analysis recorded on the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and gastrocnemius lateralis (LG). The 10 minutes of WBV showed an increase in muscular flexibility, associated with a decrease of EMG activity in BF (P < .01) and jump height. The latter was associated with a reduction of EMGs activity in BF (P < .01). The control group did not show any significant difference in all considered parameters. These results support the hypothesis that 10 minutes of WBV had effects on flexibility and explosive strength performance influencing neuromuscular behavior through inhibitor effects on antagonist muscles more than the stretch reflex activity on agonist muscles.

Shuttle swimming test in young water polo players: reliability, responsiveness and age related value

BACKGROUND This study investigated the applicability of a sport-specific test, the Shuttle Swim Test, in young water polo players to measure RSA. The aims were: to assess the reliability and to measure the responsiveness of the SST in young water polo athletes, and to provide age-related values of SST. METHODS Three hundred thirty-three elite athletes (18.3±5.1 years) were involved in the study. Of these, 99 were young people under 13 (13.1±0.5 years) who also underwent measurements for reliability and responsiveness of the SST The following six measures was used to assess anthropometric characteristics of the sample: height, weight, chest circumference, hip circumference, waist circumference, and arm span. Two performance measures were performed on dry land: push up and chin up. RESULTS Reliability and responsiveness were measured by comparing the average speed of two trials: SST1 was 1.48±0.13 m·s-1 and SST2 1.47±.12 m·s-1. The SST showed good reliability in younger athletes (r=0.96). The Minimal Detectable Change is 0.06 m·s-1 (6 seconds of the total time) which corresponds to 3.6% of the average value measured, confirming the good responsiveness of the test. CONCLUSIONS Coaches and researchers can use this value in the interpretation of the SST test results: changes below these values could be related to a measurement error. The various age-related values reported may help technicians to better interpret the performance of their athletes during competition.