S D'Ottavio

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.

Competitive-Level Differences in Yo-Yo Intermittent Recovery and Twelve Minute Run Test Performance in Soccer Referees

The aim of this study was to examine yo-yo intermittent recovery test (Yo-Yo test) and 12-minute run test (12MRT) performances in experienced soccer referees of different competitive levels. Three groups (n = 14 each) of experienced Italian soccer referees officiating in the first (series AB, top-level), third (series C, medium-level), and fourth (series D, low-level) division, were randomly submitted to the 12MRT and the Yo-Yo test during 2 testing sessions, 48-hours apart. 12MRT performances were 3,000 ± 112 m; 2,894 ± 99 m; and 2,896 ± 171 m for top-level, medium-level and low-level referees, respectively (p > 0.05). In the Yo-Yo test, the top-level, medium-level, and low-level referees covered 1,874 ± 431 m; 1,360 ± 172 m; and 1,272 ± 215 m, respectively. The test performances of top-level referees in the Yo-Yo test was significantly different from those scored by medium-level and low-level referees (p < 0.05). After the Yo-Yo test, blood lactate concentrations (BLC) were higher in the medium-level and low-level referees compared with the top-level referees (p < 0.05). The results of the present study show that the Yo-Yo test and not the 12MRT can discriminate endurance performance in experienced elite level soccer referees. With respect to its discriminative and match performance validity, the Yo-Yo test may be considered a relevant field test to assess endurance preparedness for experienced soccer referees and a useful tool in talent selection.

Cardiorespiratory responses to Yo-yo Intermittent Endurance Test in nonelite youth soccer players.

This study examined the validity of the Yo-yo Intermittent Endurance Test (Level 1; YYIET) as indicator of aerobic power in youth soccer players. Cardiorespiratory responses were determined in 18 moderately trained nonelite youth soccer players (age, 16.6 ± 0.8 years; height, 178.7 ± 6.2 cm; body mass, 69.8 ± 6.0 kg; &OV0312;O2 peak, 52.8 ± 7.4 ml·kg−1·min−1) while performing the YYIET and an incremental treadmill test. Maximal heart rate (HRmax), respiratory exchange ratio (RER), O2 pulse, &OV0312;O2 peak, and maximal ventilation (&OV0312;Emax) were measured. Group YYIET &OV0312;O2 peak, HRmax, RER, and O2 pulse were not significantly different from treadmill responses (p > 0.05). &OV0312;E-max was significantly lower (p < 0.05) during the YYIET compared to the treadmill condition. No significant correlation was found between treadmill &OV0312;O2 peak and YYIET performance (p > 0.05). This study showed that the YYIET elicits peak &OV0312;O2 and HR responses. However, YYIET performance results were not related to &OV0312;O2peak measured in laboratory. Furthermore, the individual &OV0312;O2peak reached during the TM did not reflect the &OV0312;O2 peak obtained during the YYIET, as shown by the large limits of agreement. As a consequence, compared to other shuttle run field tests, YYIET seems to be a weak indicator of aerobic power in youth moderately trained youth soccer player.

Relation between Individualized Training Impulses and Performance in Distance Runners

PURPOSE The aim of this study was to develop a method to monitor responses to training loads on an individual basis in recreational long-distance runners (LDR) through training impulses (TRIMP) analysis. The hypothesis tested was that TRIMP on the basis of individually determined weighting factors could result in a better quantification of training responses and performance in LDR in comparison to methods on the basis of average-based group values. METHODS The training load responses of eight LDR (aged 39.9 +/- 6.5 yr) were monitored using a modified version of the average-based TRIMP called individualized TRIMP (TRIMPi) during a period of 8 wk. The TRIMPi was determined in each LDR using individual HR and lactate profiles determined during an incremental treadmill test. Training-induced effects on performance (5- and 10-km races) and changes in submaximal aerobic fitness (speeds at selected blood lactate concentrations of 2 and 4 mmol x L(-1)) were assessed before and at the end of the training intervention. RESULTS Speed at 2 mmol x L(-1) (+21.3 +/- 5.2%, P < 0.001) and 4 mmol x L(-1) (+10.6 +/- 2.4%, P < 0.01) concentrations significantly increased after training. Improvements in running speed (%) at 2 mmol x L(-1) (r = 0.87, P = 0.005) and 4 mmol x L(-1) (r = 0.74, P = 0.04) concentrations were significantly related to weekly TRIMPi sum. No significant relationship between any variable was detected when average-based group values were used. The TRIMPi was significantly related to 5000- (r = -0.77; P = 0.02) and 10,000-m track performances (r = -0.82; P = 0.01). CONCLUSIONS Individualized TRIMP is a valid tool in tracking fitness (speed at 2 and 4 mmol x L(-1)) and performance (i.e., 5000- and 10,000-m races) in LDR and is more valuable than the methods on the basis of average-based group values. TRIMPi could predict race performance in LDR.

Age-related effects on fitness performance in elite-level soccer referees

Elite soccer referees usually achieve the peak of their officiating careers at an average age that is considerably older than that observed in competitive matched soccer players. As ageing has been reported to negatively affect physical performance, the aim of this study was to investigate the effect of ageing on fitness performance in elite-level soccer referees. Thirty-six elite-level soccer referees were grouped into young (Y, n = 12), average (A, n = 14), and old (O, n = 10) groups, according to their age and observed for field test performance (countermovement jump [CMJ], 50-m and 200-m sprints, and 12-minute running for distance). Results showed a significant age effect on CMJ (r = 20.52, p < 0.001), 200 m (r = 0.51, p < 0.001), and 12-minute time trial running (r = 20.52, p < 0.001). Y jumped higher than A and O groups (p < 0.05) and were faster than O over 200 m (p < 0.05). No group effect was observed for 12-minute run and 50-m performance (p > 0.05), respectively. Sixteen of the 36 referees were further examined for selected physiological variables and grouped into 2 equal (n = 8) age groups (young and old, Y1 and O1, respectively). VO2max was higher in Y1 (p < 0.05), but O1 attained performances similar to Y1 running at selected blood lactate speeds (4 mmol L-1, p > 0.05). Although older referees demonstrated acceptable fitness levels, younger officials should ensure that they develop appropriate levels of aerobic and anaerobic fitness to be able to match the demands placed upon them while refereeing throughout their careers. To promote this, fitness test standards should be age related.

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.

Match Analysis and Temporal Patterns of Fatigue in Rugby Sevens

Abstract Granatelli, G, Gabbett, TJ, Briotti, G, Padulo, J, Buglione, A, D’Ottavio, S, and Ruscello, BM. Match analysis and temporal patterns of fatigue in rugby sevens. J Strength Cond Res 28(3): 728–734, 2014—Rugby sevens is a rapidly growing sport. Match analysis is increasingly being used by sport scientists and coaches to improve the understanding of the physical demands of this sport. This study investigated the physical and physiological demands of elite mens rugby sevens, with special reference to the temporal patterns of fatigue during match play. Nine players, 4 backs and 5 forwards (age 25.1 ± 3.1 years) participated during 2 “Roma 7s” international tournaments (2010 and 2011). All the players were at the professional level in the highest Italian rugby union, and 5 of these players also competed at the international level. During the matches (n = 15), the players were filmed to assess game performance. Global positioning system, heart rate (HR), and blood lactate (BLa) concentration data were measured and analyzed. The mean total distance covered throughout matches was 1,221 ± 118 m (first half = 643 ± 70 m and second half = 578 ± 77 m; with a decrease of 11.2%, p > 0.05, Effect Size [ES] = 0.29). The players achieved 88.3 ± 4.2 and 87.7 ± 3.4% of the HRmax during the first and second halves, respectively. The BLa for the first and second halves was 3.9 ± 0.9 and 11.2 ± 1.4 mmol·L−1, respectively. The decreases in performance occurred consistently in the final 3 minutes of the matches (−40.5% in the distance covered per minute). The difference found in relation to the playing position, although not statistically significant (p = 0.11), showed a large ES (&eegr;2 = 0.20), suggesting possible practical implications. These results demonstrate that rugby sevens is a demanding sport that places stress on both the anaerobic glycolytic and aerobic oxidative energy systems. Strength and conditioning programs designed to train these energy pathways may prevent fatigue-induced reductions in physical performance.

Footstep Manipulation during Uphill Running

The present study investigated the effects of step frequency manipulation during training on slopes (2%) on biomechanical parameters at Iso-Efficiency Speed (without increasing the metabolic demand). 24 male marathon runners were randomly allocated to one of 2 training groups for 3 weeks: step frequency manipulation group (SFM, n=12) and free step frequency group (SFF, n=12). Lower limb kinematic parameters were measured before and after the 3 weeks training. The SFM group increased step length 4.30% (p<0.001), flight time 29.48% (p<0.001) and decreased contact time 14% (p<0.01). These findings coincide with characteristics of better running performances. The SFF group did not elicit such results. The results from the study could help coaches to devise training methods which could improve an athletes performance through increasing step length. The method provided may aid faster race times for athletes.