Workload, fatigue and muscle damage in an U20 rugby union team over an intensified international tournament

Purpose: This study examined the effects of an intensified tournament on workload, perceptual and neuromuscular fatigue and muscle damage responses in an international under-20 rugby union team. Methods: Players were subdivided into two groups according to match-play exposure time: high (HEG, n=13) and low (LEG, n=11). Measures monitored over the 19-day period included training session (n=10) and match (n=5) workload determined via global positioning systems and session ratings of perceived exertion (sRPE). Wellbeing scores, countermovement jump height performance (CMJ) and blood creatine kinase [CK]b concentrations were collected at various time points. Results: Analysis of workload cumulated across the tournament entirety for training and match-play combined showed that high-speed running distance was similar between groups while a very likely larger sRPE load was reported in HEG vs. LEG. In HEG high-speed activity fluctuated across the 5 successive matches albeit with no clear trend for a progressive decrease. No clear tendency for a progressive decrease in wellbeing scores prior to or following matches was observed in either group. In HEG trivial to possibly small reductions in post-match CMJ performance were observed while unclear to most likely moderate increases in pre-match [CK]b concentrations occurred until prior to match 4. Conclusion: The magnitude of match-to-match changes in external workload, perceptual and neuromuscular fatigue and muscle damage was generally unclear or small. These results suggest that irrespective of exposure time to match-play players generally maintained performance and readiness to play across the intensified tournament. These findings support the need for holistic systematic player monitoring programmes

Can we use GPS for assessing sprinting performance in rugby sevens? A concurrent validity and between-device reliability study

Purpose: The purpose of this study was to (1) provide data on maximal sprinting speed (MSS) and maximal acceleration (Amax) in elite rugby sevens players measured with GPS devices, (2) test the concurrent validity of the signal derived from a radar device and a commercially available 16 Hz GPS device, and (2) assess the between-device reliability of MSS and Amax of the same GPS. Methods: Five well-trained rugby players participated. A concurrent validity protocol compared the GPS units and a radar device (Stalker ATS II). The between-device reliability of the GPS signal during maximal sprint running was also assessed using 6 V2 GPS units (Sensoreverywhere, Digital Simulation, Paris, France) attached to a custom-made steel sled and pushed by one athlete who performed 15 linear 40m sprints. Results: CV ranged from 0.5, ±0.1 % for MSS and smoothed MSS to 6.4, ±1.1 % for Amax. TEM was trivial for MSS and smoothed MSS (0.09, ±0.01) and small for Amax and smoothed Amax (0.54, ±0.09 and 0.39, ±0.06 respectively). Mean bias ranged from -1.6, ±1.0% to -3.0, ±1.1 % for smoothed MSS and MSS respectively. TEE were small (2.0, ±0.55 to 1.6, ±0.4%, for MSS and smoothed MSS respectively. Discussion: The main results indicate that the GPS units were highly reliable for assessing MSS and provided acceptable signal to noise ratio for measuring Amax, especially when a smoothing 0.5-s moving average is used. This 16 Hz GPS device provides sport scientists and coaches with an accurate and reliable means to monitor running performance in elite rugby sevens

Tracking Fat-free Mass Changes Over a Competitive Season in Elite Soccer Players

The assessment of body composition in athletes throughout a competitive season can provide valuable information for coaches and practitioners as part of a general health assessment and to track training adaptations across a season. However, limited data are available to inform the capacity of common methods to accurately track longitudinal body composition changes in elite athletes. PURPOSE: The purpose of this study was to determine the validity of common body composition techniques and their associated prediction equations to track fat-free mass (FFM) in elite soccer players over a competitive season. METHODS: A sample of 21 elite soccer players participated in this observational, 4-timepoint study throughout a competitive season (T0 [mid-October], T1 [mid-December], T2 [mid-February], and T3 [end of April]). Participants underwent body composition assessments utilizing dual-energy X-ray absorptiometry (DXA), bioimpedance, and skinfolds. A modified 4-compartment (4C) model was produced using DXA and bioimpedance data, and several common skinfold prediction equations were also applied. Two-way repeated measures analysis of variance (ANOVA) tests were performed for FFM, with method and time as within-subject factors. Follow up testing was performed using one-way ANOVAs for simple main effects of method and time, as well as subsequent pairwise comparisons using t-tests. Statistical significance was accepted at p\u3c0.05. RESULTS: Statistically significant condition × time interactions were observed for FFM (p≤0.0005). Follow up one-way ANOVAs indicated simple main effects of time were present for FFM in all methods (p≤0.05); follow up pairwise comparisons for FFM demonstrated significant differences between time points for only four methods (DXA, 4C model, Civars equation, and Reilly equation), with the largest number of distinct changes detected via DXA. Both the Civars and Reilly equations detected increases in FFM between T0 and T3 and between T2 and T3. CONCLUSION: These findings suggest that when more advanced methods are not available, the Civars and Reilly skinfold equations may be suitable options for tracking FFM changes in elite soccer players throughout a full competitive season

Reply to Lewin and O’Driscoll: Comment on: “Monitoring of Post-match Fatigue in Professional Soccer: Welcome to the Real World”

Photograph of construction of Lohman's Crossing bridge, showing man walking toward vehicle which is partly submerged in water

Monitoring of Post-match Fatigue in Professional Soccer: Welcome to the Real World.

Participation in soccer match-play leads to acute and transient subjective, biochemical, metabolic and physical disturbances in players over subsequent hours and days. Inadequate time for rest and regeneration between matches can expose players to the risk of training and competing whilst not entirely recovered. In professional soccer, contemporary competitive schedules can require teams to compete in excess of 60 matches over the course of the season with periods of fixture congestion occurring, prompting much attention from researchers and practitioners to the monitoring of fatigue and readiness to play. A comprehensive body of research has investigated post-match acute and residual fatigue responses. Yet the relevance of the research for professional soccer contexts is debatable, notably in relation to the study populations and designs employed. Monitoring can indeed be invasive, expensive, time inefficient, and difficult to perform routinely and simultaneously in a large squad of regularly competing players. Uncertainty also exists regarding the meaningfulness and interpretation of changes in fatigue response values and their functional relevance, and practical applicability in the field. The real-world need and cost-benefit of monitoring must be carefully weighed up. In relation to professional soccer contexts, this opinion paper intends to (1) debate the need for post-match fatigue monitoring; (2) critique the real-world relevance of the current research literature; (3) discuss the practical burden relating to measurement tools and protocols, and the collection, interpretation and application of data in the field; and (4) propose future research perspectives

New laboratory measurements of CH4 in Titan's conditions and a reanalysis of the DISR near-surface spectra at the Huygens landing site

International audienceLaboratory spectra of methane-nitrogen mixtures have been recorded in the near-infrared range (1.0 - 1.65 µm) in conditions similar to Titan's near surface, to facilitate the interpretation of the DISR/DLIS spectra taken during the last phase of the descent of the Huygens Probe, when the surface was illuminated by a surface science lamp. We used a 0.03 cm-1 spectral resolution, adequate to resolve the lines at high pressure (pN2 ~ 1.5 bar). By comparing the laboratory spectra with synthetic calculations in the well-studied ν2 + 2ν3 band (7515-7620 cm-1), we determine a methane absorption column density of 178±20 cm-am and a temperature of 118±10 K in our experiment. From this, we derive the methane absorption coefficients over 1.0-1.65 µm with a 0.03 cm-1 sampling, allowing for the extrapolation of the results to any other methane column density under the relevant pressure and temperature conditions. We then revisit the calibration and analysis of the Titan "lamp-on" DLIS spectra. We infer a 5.1±0.8 % methane mixing ratio in the first 25 m of Titan's atmosphere. The CH4 mixing ratio measured 90 sec after landing from a distance of 45 cm is found to be 0.92±0.25 times this value, thus showing no post-landing outgassing of methane in excess of ̴ 20 %. Finally, we determine the surface reflectivity as seen from 25 m and 45 cm and find that the 1500 nm absorption band is deeper in the post-landing spectrum as compared to pre-landing

In-match physical performance fluctuations in international rugby sevens competition

It is widely recognised that the physical demands in rugby sevens are high especially in comparison to the 15-aside version. The aim of this study was to assess fluctuations in physical performance (running and contact loads) in international rugby sevens competition. Altogether, 32 matches played by an international team in the HSBC World Sevens Series were analyzed (63 match-observations). Players wore a validated GPS device (SensorEverywhere, France) sampling at 16Hz while an operator coded every contact action (tackles, collisions, mauls, scrums) using video analysis software (SportsCode, USA). Running load was assessed using total distance travelled (m), individually determined high-speed distance (covered at velocities > maximal aerobic speed, m) and very-high speed distance (covered at velocities > 85% maximal sprinting speed, m). The frequency of accelerations (actions > 2.5 m.s-1) and high-intensity actions (HIA, sum of high-velocity runs, accelerations and contact-related actions, n) were also calculated. A magnitude-based inferential approach to statistics was adopted and effect sizes quantified. Findings showed: 1) a small decrease in high speed distance and number of accelerations performed during the second- versus the first-half of play suggesting a decline in running performance. (2) a moderately higher total distance and high-speed distance covered during the first and final 1-min period compared to the average for other 1-min periods, suggesting a specific reverse ‘J-shape’ pacing profile 3) a most likely decrease in total distance, high-speed running, and to a lesser extent the number of accelerations declined following the peak 1-min period of the game. These findings provide pertinent information on changes in running performance over the course of international sevens and have implications for physical conditioning strategies

Upper-body resistance training following soccer match play: Compatible, complementary, or contraindicated?

Purpose: During heavily congested schedules, professional soccer players can experience exacerbated fatigue responses, which are thought to contribute to an increased risk of injury. Given that match-induced residual fatigue can last up to 72 hours, many coaches naturally prioritize recovery in the days immediately following match day. While it is intuitive for coaches and training staff to decrease the amount of auxiliary training practices to focus on recovery, prescribing upper-body resistance training on the day after match play has recently emerged as a specific training modality in this context. While these sessions may be implemented to increase training stimulus, there are limited data available regarding the efficacy of such a practice to improve recovery kinetics. Methods: In this narrative review, the authors look at the theoretical implications of performing upper-body resistance training on the day after match play on the status of various physiological and psychological systems, including neuromuscular, metabolic, hormonal, perceptual, and immunological recovery. Results: The available evidence suggests that in most cases this practice, as currently implemented (ie, low volume, low intensity), is unlikely to be complementary (ie, does not accelerate recovery) but is potentially compatible (ie, does not impair recovery). Conclusion: Overall, because the perception of such sessions may be player dependent, their programming requires an individualized approach and should take into account match dynamics (eg, fixture scheduling, playing time, travel)

The travel demands of an elite rugby sevens team: Effects on objective and subjective sleep parameters

Purpose: To explore the effects of travel related to international rugby sevens competition on sleep patterns. Methods: Seventeen international male rugby sevens players participated in this study. Sleep assessments were performed daily during two separate Sevens World Series competition legs (Oceania and America). The duration of each competition leg was subdivided into key periods (pre-tour, pre-competition, tournament 1 and 2, relocation and post-tour) lasting 2 to 7 nights. Linear mixed models in combination with magnitude-based decision were used to assess 1) the difference between pre-season and key periods and 2) the effect of travel direction (eastward or westward). Results: Shorter total sleep time (hh:mm) was observed during tournament 2 (mean ± SD, 06:16 ± 01:08), relocation (06:09 ± 01:09) and pre-tour week (06:34 ± 01:24) compared with pre-season (06:52 ± 01:00). Worse sleep quality (AU) was observed during tournament 1 (6.1 ± 65 2.0) and 2 (5.7 ± 1.2) as well as during the relocation week (6.3 ± 1.5) than during pre-season (6.5 ± 1.8). When traveling eastward compared with westward, earlier fall asleep time was observed during tournament 1 (ES -0.57, 90%CI [-1.12 to -0.01]), relocation week (-0.70 [-1.11 to -0.28]), and post-tour (-0.57 [-0.95 to -0.18]). However, possibly trivial and unclear differences were observed during pre-competition week (0.15 [-0.15 to 0.45]) and tournament 2 (0.81 [-0.29 to 1.91]). Conclusion: Sleep patterns of elite rugby sevens players are robust to the effects of long-haul travel and jet lag. However, staff should consider promoting sleep during the tournament and 73 relocation week