Left ventricular function and mechanics in backs and forwards elite rugby union players.

ABSTRACTPurpose: The aim of the present study was to assess left ventricular (LV) morphological and regional functional adaptations in backs and forwards elite rugby union (RU) players. METHODS: Thirty-nine elite male RU players and twenty sedentary controls have been examined using resting echocardiography. RU players were divided into two groups, forwards (n = 22) and backs (n = 17). Evaluations included tissue Doppler and 2D speckle-tracking analysis to assess LV strains and twisting mechanics. RESULTS: The elite RU players exhibited an LV remodelling characterized by an increase in LV mass indexed to body surface area (82.2 ± 13.2 vs. 99.9 ± 16.1 and 119.7 ± 13.4 g.m-2, in controls, backs and forwards; P < .001). Compared to backs, forwards exhibited lower global longitudinal strain (19.9 ± 2.5 vs. 18.0 ± 1.6%; P < .05), lower early diastolic velocity (16.5 ± 1.8 vs. 15.0 ± 2.3 cm.s-1; P < .05) and lower diastolic longitudinal strain rate (1.80 ± 0.34 vs. 1.54 ± 0.26 s-1; P < .01), especially at the apex. LV twist and untwisting velocities were similar in RU players compared to controls, but with lower apical (-46.2 ± 22.1 vs. -28.2 ± 21.7 deg.s-1; P < .01) and higher basal rotational velocities (33.9 ± 20.9 vs. 48.4 ± 20.7 deg.s-1; P < .05). CONCLUSION: RU players exhibited an increase in LV mass which was more pronounced in forwards. In forwards, LV global longitudinal strain was depressed, LV filling pressures were decreased, and LV relaxation depressed at the apex.Highlights Elite RU players exhibited LV hypertrophy, especially in forwards players.LV regional function suggested a drop in LV relaxation and an increase in LV filling pressures in RU players, with higher alterations in forwards.LV remodelling was associated with regional alterations in torsional mechanics: higher rotations and rotational diastolic velocities at the basal level of LV but lower rotation and rotational diastolic velocities at the apex were observed in RU players.

Sprint Acceleration Mechanical Outputs Derived from Position- or Velocity-Time Data: A Multi-System Comparison Study.

To directly compare five commonly used on-field systems (motorized linear encoder, laser, radar, global positioning system, and timing gates) during sprint acceleration to (i) measure velocity−time data, (ii) compute the main associated force−velocity variables, and (iii) assess their respective inter-trial reliability. Eighteen participants performed three 40 m sprints, during which five systems were used to simultaneously and separately record the body center of the mass horizontal position or velocity over time. Horizontal force−velocity mechanical outputs for the two best trials were computed following an inverse dynamic model and based on an exponential fitting of the position- or velocity-time data. Between the five systems, the maximal running velocity was close (7.99 to 8.04 m.s−1), while the time constant showed larger differences (1.18 to 1.29 s). Concurrent validity results overall showed a relative systematic error of 0.86 to 2.28% for maximum and theoretically maximal velocity variables and 4.78 to 12.9% for early acceleration variables. The inter-trial reliability showed low coefficients of variation (all <5.74%), and was very close between all of the systems. All of the systems tested here can be considered relevant to measure the maximal velocity and compute the force−velocity mechanical outputs. Practitioners are advised to interpret the data obtained with either of these systems in light of these results.

How does playing position affect fatigue-induced changes in high-intensity locomotor and micro-movements patterns during professional rugby union games?

AbstractWe questioned whether changes in high-intensity locomotor and micro-movements patterns between the first and second part of each half depend on playing position in the 2014-2015 European rugby union championship winning team. Thirty-three rugby players were grouped according to five playing positions. Players were equipped with micro-electromechanical system including a GPS sampling at 10 Hz and high temporal resolution micro-sensors during 17 Top14 and 7 European games. High-speed movements (HSM), high-intensity accelerations (HIA), repeated high-intensity efforts (RHIE), and high-intensity micro-movements (HIMM) were subsequently compared between four 20-min game periods. No significant group × time interactions were observed for any locomotor variables (p > 0.283). Irrespectively of playing position, the number of HSM (p = 0.019), decreased from 0-20 min to 60-80 min as well as from 40-60 to 60-80 min (p < 0.001) with HIA (p = 0.020) and RHIE (p < 0.001). Significant group × time interaction was found for HIMM (p = 0.03) with a significant decrease observed in back row forwards from 0-20 to 60-80 min periods (-17.5%; ES = 0.6; p = 0.031). In elite rugby union, fatigue-induced changes during the last 20 min are independent from playing positions in high-intensity locomotor patterns in contrary to HIMM. Training drills that include specific RHIE (high-speed and HIA efforts) may be useful to postpone match-related fatigue.

High-intensity Activity in European vs. National Rugby Union Games in the best 2014-2015 Team.

The purpose of this study is to evaluate the influence of competition level on running patterns for five playing position in the most successful 2014-2015 European rugby union team. Seventeen French rugby union championship and seven European rugby Champions Cup games were analysed. Global positioning system (sampling: 10 Hz) were used to determine high-speed movements, high-intensity accelerations, repeated high-intensity efforts and high-intensity micro-movements characteristics for five positional groups. During European Champions Cup games, front row forwards performed a higher number of repeated high-intensity efforts compared to National championship games (5.8±1.6 vs. 3.6±2.3; +61.1%), and back row forwards travelled greater distance both at high-speed movements (3.4±1.8 vs. 2.4±0.9 m·min-1; +41.7%) and after high-intensity accelerations (78.2±14.0 vs. 68.1 ±13.4 m; +14.8%). In backs, scrum halves carried out more high-intensity accelerations (24.7±3.1 vs. 14.8±5.0; +66.3%) whereas outside backs completed a higher number of high-speed movements (62.7±25.4 vs. 48.3±17.0; +29.8%) and repeated high-intensity efforts (13.5±4.6 vs. 9.7±4.9; +39.2%). These results highlighted that the competition level affected the high-intensity activity differently among the five playing positions. Consequently, training programs in elite rugby should be tailored taking into account both the level of competition and the high-intensity running pattern of each playing position.

Repeated-sprint training in hypoxia induced by voluntary hypoventilation improves running repeated-sprint ability in rugby players.

PURPOSE: The goal of this study was to determine the effects of repeated-sprint training in hypoxia induced by voluntary hypoventilation at low lung volume (VHL) on running repeated-sprint ability (RSA) in team-sport players. METHODS: Twenty-one highly trained rugby players performed, over a 4-week period, seven sessions of repeated 40-m sprints either with VHL (RSH-VHL, n = 11) or with normal breathing (RSN, n = 10). Before (Pre-) and after training (Post-), performance was assessed with an RSA test (40-m all-out sprints with a departure every 30 s) until task failure (85% of the reference velocity assessed in an isolated sprint). RESULTS: The number of sprints completed during the RSA test was significantly increased after the training period in RSH-VHL (9.1 ± 2.8 vs. 14.9 ± 5.3; +64%; p < .01) but not in RSN (9.8 ± 2.8 vs. 10.4 ± 4.7; +6%; p = .74). Maximal velocity was not different between Pre- and Post- in both groups whereas the mean velocity decreased in RSN and remained unchanged in RSH-VHL. The mean SpO2 recorded over an entire training session was lower in RSH-VHL than in RSN (90.1 ± 1.4 vs. 95.5 ± 0.5%, p < .01). CONCLUSION: RSH-VHL appears to be an effective strategy to produce a hypoxic stress and to improve running RSA in team-sport players.