Monitoring workloads in collision sports: External load measures alone may not provide the full picture

PURPOSE: To compare the external loads and external:internal load ratios (EL:IL) during match-play of adolescent collision sport athletes playing at both elite (i.e., academy) and sub-elite (i.e., school) standards. METHODS: Following ethics approval, seventeen elite adolescent male rugby union players (mean ± SD age = 17 ± 1 years) were recruited for this study. Global positioning system (GPS) locomotor (i.e., relative distance [RD; m·min-1], low speed activity [LSA; relative distance <61% maximum velocity [Vmax]], high speed running [HSR; relative distance ≥61% Vmax]), and accelerometer (relative PlayerLoadTM [RPL; AU·min-1], PLSLOW [relative accelerations <2 m·s-1], PLFAST [relative accelerations ≥2 m·s-1]) external loads, and session rating of perceived exertion (sRPE) internal load measures were obtained from 22 matches resulting in 86 match files (39 sub-elite and 47 elite match files; 5 ± 2 match files per subject). Perceptual wellbeing measures (i.e., fatigue, sleep quality, upper-body and lower-body soreness, stress, and mood) were also recorded using a 5-point Likert scale on the mornings pre- and post-match. Data were analysed using Cohen’s d effect sizes (d) and magnitude-based inferences. RESULTS: Differences in external loads were unclear between playing standards for RD (d = -0.2) and RPL (d = 0.0). However, subjects’ EL:IL were very likely lower during elite compared to sub-elite matches for both RD:sRPE (d = -1.0) and RPL:sRPE (d = -0.8), due to the very likely greater sRPE during elite matches (d = -1.1). There were unclear differences between sub-elite and elite matches for distribution of GPS and accelerometer variables (i.e., LSA, HSR, PLSLOW, and PLFAST; Table 1). Changes in total perceptual wellbeing were possibly greater following elite compared to sub-elite matches, with unclear differences for changes in sleep quality, lower-body soreness, stress and mood. However, changes in perceptual fatigue and upper-body soreness were both likely greater following elite matches. CONCLUSIONS: Adolescent rugby union players had similar locomotor and accelerometer external loads (i.e., RD, LSA, HSR, RPL, PLSLOW and PLFAST) during both elite and sub-elite standard matches. However, EL:IL was substantially reduced in higher standard matches, indicating a higher perception of effort for a given external load. Greater changes in perceptual fatigue and upper-body soreness following elite match-play may be related to greater magnitude of collision-based activity at higher playing standards. This may be due to the increased body mass and running velocities of opponents at higher playing standards, which may not be fully accounted for using external load measures alone. PRACTICAL APPLICATION: As collision sports require more than just movement and acceleration demands, the inclusion of subjective load measures (i.e., sRPE) or EL:IL may provide a further insight to the true demands of training or match-play than GPS and accelerometer data alone

Validity of Daily and Weekly Self-Reported Training Load Measures in Adolescent Athletes

The primary aim of the study was to assess the level of agreement between the criterion session-rating of perceived exertion (sRPE30min) and a practical measure of a self-reported web-based training load questionnaire 24-hours post-training (sRPE24h) in adolescent athletes. The secondary aim was to assess the agreement between weekly summated sRPE24h values (ƩsRPE24h) and a weekly web-based training diary (sRPEweekly) for all field-based training accumulated on a subsequent training week. Thirty-six male adolescent rugby players (age 16.7 ± 0.5 years) were recruited from a regional academy. sRPE30min measures were recorded 30-minutes following a typical field-based training session. Participants then completed the sRPE24h via a web-based training load questionnaire 24-hours post-training, reporting both session duration and intensity. In addition, on a subsequent week, participants completed the sRPE24h daily and then completed the sRPEweekly at the end of the week, using the same web-based platform, to recall all field-based training session durations and intensities over those seven days. Biases were trivial between sRPE30min and sRPE24h for sRPE (0.3% [-0.9 to 1.5]), with nearly perfect correlations (0.99 [0.98 to 0.99), and small typical error of the estimate (TEE; 4.3% [3.6 to 5.4]). Biases were trivial between ƩsRPE24h and sRPEweekly for sRPE (5.9% [-2.1 to 14.2]), with very large correlations (0.87 [0.78 to 0.93]), and moderate TEE 28.5% [23.3 to 36.9]). The results of this study show that sRPE24h is a valid and robust method to quantify training loads in adolescent athletes. However, sRPEweekly was found to have a substantial TEE (29%), limiting practical application

The influence of resistance training experience on the between-day reliability of commonly used strength measures in male youth athletes

The purpose of this study was to determine the between-day reliability of commonly used strength measures in male youth athletes, while considering resistance training experience. Data were collected on 25 male athletes over two testing sessions, with 72 hours rest between, for the 3RM front squat, chin up and bench press. Subjects were initially categorized by resistance training experience (inexperienced; 6-12 months, experienced; >2 years). The assessment of the between-day reliability (coefficient of variation [CV%]) showed the front squat (experienced: 2.90%; inexperienced: 1.90%), chin up (experienced: 1.70%; inexperienced: 1.90%), and bench press (experienced: 4.50%; inexperienced: 2.40%) were all reliable measures of strength in both groups. Comparison between groups for the error of measurement for each exercise showed trivial differences. When both groups were combined, the CV% for the front squat, bench press, and chin up were 2.50%, 1.80%, and 3.70%, respectively. This study provides scientists and practitioners with the between-day reliability reference data to determine real and practical changes for strength in male youth athletes with different resistance training experience. Furthermore, this study demonstrates that 3RM front squat, chin up and bench press are reliable exercises to quantify strength in male youth athletes

Between-Day Reliability and Sensitivity of Common Fatigue Measures in Rugby Players.

This study established the between-day reliability and sensitivity of a countermovement jump (CMJ), plyometric push-up, wellbeing questionnaire and whole blood creatine kinase concentration [CK] in elite male youth rugby union players. The study also established the between-day reliability of 1, 2 or 3 CMJ and plyometric push-up attempts. Twenty-five players completed tests on 2 occasions separated by 5 days (of rest). Between-day typical error (TE), coefficient of variation (CV) and smallest worthwhile change (SWC) were calculated for the wellbeing questionnaire, [CK] and CMJ and plyometric push-up metrics (peak/mean power, peak/mean force, height, flight-time and flight-time to contraction-time ratio) for 1 maximal effort or taking the highest score from 2 or 3 maximal efforts. The results from this study would suggest that CMJ mean power (2 or 3 attempts), peak force or mean force, and plyometric push-up mean force (from 2 or 3 attempts) should be used for assessing lower- and upper-body neuromuscular function respectively, due to both their acceptable reliability (CV 5% (7.1% and 26.1% respectively) and poor sensitivity (CV>SCW). The findings from this study can be used when interpreting fatigue markers to make an objective decision about a player's readiness to train or compete

We know they train, but what do they do? Implications for coaches working with adolescent rugby union players

Limited information is available regarding the training loads (TLs) of adolescent rugby union players. One-hundred and seventy male players (age 16.1 ± 1.0 years) were recruited from ten teams representing two age categories (under-16 and under-18) and three playing standards (school, club and academy). Global positioning systems, accelerometers, heart rate and session-rating of perceived exertion (s-RPE) methods were used to quantify mean session TLs. Session demands differed between age categories and playing standards. Under-18 academy players were exposed to the highest session TLs in terms of s-RPE (236 ± 42 AU), total distance (4176 ± 433 m), high speed running (1270 ± 288 m) and PlayerLoadTM (424 ± 56 AU). Schools players had the lowest session TLs in both respective age categories. Training loads and intensities increased with age and playing standard. Individual monitoring of TL is key to enable coaches to maximise player development and minimise injury risk

Physical demands of representative match play in adolescent rugby union

The purpose of this study was to quantify the physical demands of representative adolescent rugby union match-play and investigate the difference between playing positions and age groups. Players (n=112) were classified into 6 groups by playing position (forwards and backs) and age group (U16, U18, U20). The physical demands were measured using microsensor-based technology and analysed using magnitude based inferences to assess practical importance. Backs had a greater relative distance (except U16s) and a greater high-speed running distance per minute than forwards, with the magnitude of difference between the positions becoming larger in older age groups. Forwards had higher values of PlayerLoadTM per minute (accumulated accelerations from the three axes of movement) and PlayerLoadTM slow per minute (accumulated accelerations from the three axes of movement where velocity is <2 m.s-1) than backs at all age groups. Relative distance, low- and high-speed running per minute all had a trend to be lower in older age groups for both positions. PlayerLoadTM per minute was greater in U18 than U16 and U20 for both positions. PlayerLoadTM slow per minute was greater for older age groups besides the U18 and U20 comparisons, which were unclear. The contrasts in physical demands experienced by different positions reinforce the need for greater exposure to sprinting and collision based activity for backs and forwards, respectively. Given PlayerLoadTM metrics peak at U18 and locomotor demands seem to be lower in older ages, the demands of representative adolescent rugby union do not seem to be greater at U20 as expected

Visual feedback maintains mean concentric barbell velocity, and improves motivation, competitiveness, and perceived workload in male adolescent athletes

It is unknown whether instantaneous visual feedback of resistance training outcomes can enhance barbell velocity in younger athletes. Therefore, the purpose of this study was to quantify the effects of visual feedback on mean concentric barbell velocity in the back squat, and to identify changes in motivation, competitiveness, and perceived workload. In a randomised-crossover design (Feedback vs. Control) feedback of mean concentric barbell velocity was or was not provided throughout a set of 10 repetitions in the barbell back squat. Magnitude-based inferences were used to assess changes between conditions, with almost certainly greater differences in mean concentric velocity between the Feedback (0.70 ±0.04 m·s-1) and Control (0.65 ±0.05 m·s-1) observed. Additionally, individual repetition mean concentric velocity ranged from possibly (repetition number two: 0.79 ±0.04 vs. 0.78 ±0.04 m·s-1) to almost certainly (repetition number 10: 0.58 ±0.05 vs. 0.49 ±0.05 m·s-1) greater when provided feedback, while almost certain differences were observed in motivation, competitiveness, and perceived workload, respectively. Providing adolescent male athletes with visual kinematic information while completing resistance training is beneficial for the maintenance of barbell velocity during a training set, potentially enhancing physical performance. Moreover, these improvements were observed alongside increases in motivation, competitiveness and perceived workload providing insight into the underlying mechanisms responsible for the performance gains observed. Given the observed maintenance of barbell velocity during a training set, practitioners can use this technique to manipulate training outcomes during resistance trainin

Objective sleep patterns and validity of self-reported sleep monitoring across different playing levels in rugby union

Background: Growing evidence highlights that elite rugby union players experience poor sleep quality and quantity which can be detrimental for performance. Objectives: This study aimed to i) compare objective sleep measures of rugby union players between age categories over a one week period, and ii) compare self-reported measures of sleep to wristwatch actigraphy as the criterion. Methods: Two hundred and fifty-three nights of sleep were recorded from 38 players representing four different age groups (i.e. under 16, under 18, senior academy, elite senior) in a professional rugby union club in the United Kingdom (UK). Linear mixed models and magnitude-based decisions were used for analysis. Results: The analysis of sleep schedules showed that U16 players went to bed and woke up later than their older counterparts (small differences). In general, players obtained seven hours of sleep per night, with trivial or unclear differences between age groups. The validity analysis highlighted a large relationship between objective and subjective sleep measures for bedtime (r = 0.56 [0.48 to 0.63]), and get up time (r = 0.70 [0.63 to 0.75]). A large standardised typical error (1.50 [1.23 to 1.88]) was observed for total sleep time. Conclusion: This study highlights that differences exist in sleep schedules between rugby union players in different age categories that should be considered when planning training. Additionally, self-reported measures overestimated sleep parameters. Coaches should consider these results to optimise sleep habits of their players and should be careful with self-reported sleep measures

Reliability and Validity of a Medicine Ball-Contained Accelerometer for Measuring Upper-Body Neuromuscular Performance

Roe, G, Shaw, W, Darrall-Jones, J, Phibbs, PJ, Read, D, Weakley, JJ, Till, K, and Jones, B. Reliability and validity of a medicine ball-contained accelerometer for measuring upper-body neuromuscular performance. J Strength Cond Res 32(7): 1915-1918, 2018-The aim of the study was to assess the between-day reliability and validity of a medicine ball-contained accelerometer (MBA) for assessing upper-body neuromuscular performance during a throwing task. Ten professional rugby union players partook in the study. Between-day reliability was assessed from the best score attained during 2 sets of 3 throws, on 2 testing occasions separated by 7 days. Validity was assessed against a criterion measure (Optioelectronic system) during 75 throws from a subgroup of 3 participants. The MBA exhibited a small between-day error of 2.2% (90% confidence intervals; 2.0-4.6%) and an almost perfect relationship with a criterion measure (r = 0.91 [90% CIs; 0.87-0.94]). However, the mean bias and standard error were moderate (7.9% [90% CIs; 6.6-9.2%] and 4.9% [90% CIs; 4.2-5.7%], respectively). Practitioners using an MBA to assess neuromuscular performance of the upper body must take into account the overestimation and error associated with such assessment with respect to a criterion measure. However, as the error associated with between-day testing was small and testing is easy to implement in applied practice, an MBA may provide a useful tool for monitoring upper-body neuromuscular performance over time