body mass) and 3 primary performance variables (countermovement jump height [CMJ], speed [10-m sprint], aerobic capacity [Yo-Yo-intermittent recovery test level 1, Yo-Yo-IR1]). The same players performed the testing battery across 3 annual age categories: under 18 (U18), under 19 (U19), and under 20 (U
Niall Casserly, Ross Neville, Massimiliano Ditroilo and Adam Grainger
Glenn Street, Scott McMillan, Wayne Board, Mike Rasmussen and J. Michael Heneghan
A comprehensive error analysis was performed on the impulse method. To evaluate the potential errors, jump height was recalculated after altering one of the measurement or calculation techniquaes while leaving the others unchanged, and then comparing it to the reference jump height (best estimate of true jump height). Measurement techniques introduced the greatest error. Low-pass filters with cutoff frequencies < 580 Hz led to systematic underestimations of jump height, ≤26%. Low sampling frequencies (<1,080 Hz) caused jump height to be underestimated by ≤4.4%. Computational methods introduced less error. Selecting takeoff too early by using an elevated threshold caused jump height to be overestimated by ≤1.5%. Other potential sources of computational error: (a) duration of body weight averaging period; (b) method of integration; (c) gravity constant; (d) start of integration; (e) duration of offset averaging period; and (f) sample duration, introduced < 1% error to the calculated jump height. Employing the recommended guidelines presented in this study reduces total error to ≤ ±0.76%. Failing to follow the guidelines can lead to average errors as large as 26%.
Herbert Wagner, Patrick Fuchs, Andrea Fusco, Philip Fuchs, Jeffrey W. Bell and Serge P. von Duvillard
= .008), jump height in the jump shot and countermovement-jump height ( R = .71, P < .001) as well as ball velocity in the jump shot and shoulder rotation torque ( R = .84, P < .001) are shown in Figure 4 . Table 1 Anthropometrics and General and Specific Physical Performance Variables in Elite
Mayur K. Ranchordas, George King, Mitchell Russell, Anthony Lynn and Mark Russell
position, dropped down into the squat position, and then immediately jumped as high as possible. The first jump was used as a practice jump, and then two maximal jumps were performed, with 45-s rest between each jump. Countermovement jump height represents the maximal value achieved in the final two
William Abbott, Adam Brett, Emma Cockburn and Tom Clifford
CMJ height up to 36 hours, with no clear differences at 60 hours. The P value for the main interaction effect was .011. Post hoc analysis revealed significant differences in CMJ height at 12 and 36 hours postmatch ( P = .001 and .046, respectively). Figure 1 —Changes in countermovement-jump height
Llion A. Roberts, Johnpaul Caia, Lachlan P. James, Tannath J. Scott and Vincent G. Kelly
therapies have also been reported to augment recovery after rugby specifically. For example, cold-water immersion and contrast water immersion were superior to active recovery in restoring countermovement jump height and decreasing muscle soreness and creatine kinase concentrations ≤42 hours after rugby
Will Abbott, Callum Brashill, Adam Brett and Tom Clifford
Purpose: To investigate the effects of tart cherry juice (TCJ) on recovery from a soccer match in professional players. Methods: In a double-blind, placebo-controlled, crossover design, 10 male professional soccer players from the reserve team of an English Premier League Club (age 19  y, height 1.8 [0.6] m, body mass 77.3 [6.4] kg) consumed 2 × 30-mL servings of TCJ or an isocaloric cherry-flavored control drink (CON) before and after a 90-minute match and 12 and 36 hours after the match. Muscle function (countermovement jump height and reactive strength index), subjective well-being, and subjective muscle soreness were measured before and 12, 36, and 60 hours after each match. Results: Countermovement jump height was similarly reduced in the days after the match after TCJ and CON supplementation, with the greatest loss occurring at 12-hour postmatch (−5.9% [3.1%] vs −5.4% [2.9%], of baseline values, respectively; P = .966;
Tom Clifford, Will Abbott, Susan Y. Kwiecien, Glyn Howatson and Malachy P. McHugh
Purpose : To examine whether donning lower-body garments fitted with cooled phase change material (PCM) would enhance recovery after a soccer match. Methods : In a randomized, crossover design, 11 elite soccer players from the reserve squad of a team in the second-highest league in England wore PCM cooled to 15°C (PCMcold) or left at ambient temperature (PCMamb; sham control) for 3 h after a soccer match. To assess recovery, countermovement jump height, maximal isometric voluntary contraction (MIVC), muscle soreness, and the adapted Brief Assessment of Mood Questionnaire (BAM+) were measured before 12, 36, and 60 h after each match. A belief questionnaire was completed preintervention and postintervention to determine the perceived effectiveness of each garment. Results : Results are comparisons between the 2 conditions at each time point postmatch. MIVC at 36 h postmatch was greater with PCMcold versus PCMwarm (P = .01; ES = 1.59; 95% CI, 3.9–17.1%). MIVC also tended to be higher at 60 h postmatch (P = .05; ES = 0.85; 95% CI, −0.4% to 11.1%). Muscle soreness was 26.5% lower in PCMcold versus PCMwarm at 36 h (P = .02; ES = 1.7; 95% CI, −50.4 to −16.1 mm) and 24.3% lower at 60 h (P = .04; ES = 1.1; 95% CI, −26.9 to −0.874 mm). There were no between-conditions differences in postmatch countermovement jump height or BAM+ (P > .05). The belief questionnaire revealed that players felt the PCMcold was more effective than the PCMamb after the intervention (P = .004). Conclusions : PCM cooling garments provide a practical means of delivering prolonged postexercise cooling and thereby accelerate recovery in elite soccer players.
Adam Grainger, Paul Comfort and Shane Heffernan
Purpose: Partial body cryotherapy (PBC) has been shown to be beneficial for postexercise recovery; however, no study has demonstrated the effectiveness of PBC for recovery following elite rugby union training. Rugby union is a unique sport that involves high-velocity collisions and may induce greater performance decrements than other sports; thus, PBC could be beneficial. The application of PBC in “real world” has rarely been investigated during the competitive phase of a playing season and warranted investigation. Methods: In a counterbalanced sequential research design, professional rugby athletes (n = 18; age 25.4 [4.0] y; training age 7.2 [4.0] y; mass 99.8 [10.6] kg; height 188.3 [6.0] cm) were assigned to a 12-week PBC intervention, washout period (4 wk), and reassessed as their own controls. Self-reported well-being, muscle soreness, sleep quality, and countermovement jump height were assessed before and 40 hours after “real-world” training. Wilcoxon signed-rank tests and Cohen d were used for statistical analysis. Results: No differences were observed between PBC and control conditions (P > .05; d = 0.00–0.14) for well-being (−0.02% [0.08%] vs 0.01% [0.06%]), muscle soreness (−0.01% [0.11%] vs 0.01% [0.16%]), sleep quality (−0.03% [0.14%] vs 0.10% [0.29%]), or countermovement jump height (36.48–36.59 vs 38.13–37.52 cm; P = .54). Conclusions: These results suggest PBC is ineffective for the restoration of selected performance parameters during the performance maintenance phase of the competitive season. To ascertain the appropriation of its use, future investigations should seek to assess the use of cryotherapies at various phases of the elite rugby union competitive season.
Robin T. Thorpe, Anthony J. Strudwick, Martin Buchheit, Greg Atkinson, Barry Drust and Warren Gregson
To quantify the relationship between daily training load and a range of potential measures of fatigue in elite soccer players during an in-season competitive phase (17 d).
Total high-intensity-running (THIR) distance, perceived ratings of wellness (fatigue, muscle soreness, sleep quality), countermovement-jump height (CMJ), postexercise heart-rate recovery (HRR), and heart-rate variability (Ln rMSSD) were analyzed during an in-season competitive period (17 d). General linear models were used to evaluate the influence of daily fluctuation in THIR distance on potential fatigue variables.
Fluctuations in fatigue (r = −.51, large, P < .001), Ln rMSSD (r = −.24, small, P = .04), and CMJ (r = .23, small, P = .04) were significantly correlated with fluctuations in THIR distance. Correlations between variability in muscle soreness, sleep quality, and HRR and THIR distance were negligible and not statistically significant.
Perceived ratings of fatigue and Ln rMSSD were sensitive to daily fluctuations in THIR distance in a sample of elite soccer players. Therefore, these particular markers show promise as simple, noninvasive assessments of fatigue status in elite soccer players during a short in-season competitive phase.