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Purpose: To examine the relationship between cardiorespiratory and accelerometer-derived measures of exercise during trail running and determine the influence of accelerometer location. Methods: Eight trail runners (7 males and 1 female; age 26 [5] y; maximal oxygen consumption [ V ˙ O 2 ] 70 [6] mL·kg−1·min−1) completed a 7-km trail run (elevation gain: 486 m), with concurrent measurements of V ˙ O 2 , heart rate, and accelerations recorded from 3 triaxial accelerometers attached at the upper spine, lower spine, and pelvis. External exercise intensity was quantified from the accelerometers using PlayerLoad™ per minute and accelerometry-derived average net force. External exercise volume was calculated using accumulated PlayerLoad and the product of average net force and duration (impulse). Internal intensity was calculated using heart rate and V ˙ O 2 -metrics; internal volume was calculated from total energy expenditure (work). All metrics were analyzed during both uphill (UH) and downhill (DH) sections of the trail run. Results:PlayerLoad and average net force were greater during DH compared with UH for all sensor locations (P ≤.004). For all accelerometer metrics, there was a sensor position × gradient interaction (F2,1429.003; P <.001). The upper spine was lower compared with both pelvis (P ≤.003) and lower spine (P ≤.002) for all accelerometer metrics during both UH and DH running. Relationships between accelerometer and cardiorespiratory measures during UH running ranged from moderate negative to moderate positive (r = −.31 to.41). Relationships were stronger during DH running where there was a nearly perfect correlation between work and impulse (r =.91; P <.001). Conclusions: Simultaneous monitoring of cardiorespiratory and accelerometer-derived measures during trail running is suggested because of the disparity between internal and external intensities during changes in gradient. Sensor positioning close to the center of mass is recommended. [ABSTRACT FROM AUTHOR]

Purpose: To determine the reliability, usefulness, and validity of 3 different change-of-direction tests on a SpeedCourt (SCCODT) in team-sport players. Methods: For reliability and usefulness, 30 players (16 female and 14 male: age 19 ± 3 y, height 169 ± 30 cm, body mass 70 ±11 kg) performed 3 SCCODTS differing in duration (7--45 s) on 3 occasions 1 wk apart. The total sprint times (TT) and time to change direction (TCD) were analyzed for each SCCODT. For validity, 14 players performed the Illinois Agility Test (IAT) and 505 test on a separate occasion. Results: TT for all SCCODTS is reliable (ICC > .79, CV < 5%), useful (TE < SWC0.5), and valid (IAT r > .71, P < .05; 505 test r > .54, P < .05). SCCODT variable TCD may be useful (TE = SWC0.5) but shows limited reliability with ICC >.65 and a CV >5%. Conclusions: All SCCODTS are reliable, useful, and valid to detect moderate performance changes regarding TT, with limited reliability for TCD. The quality of assessment improves when players are well familiarized with the SCCODT [ABSTRACT FROM AUTHOR]

Purpose: The current investigation assessed tissue oxygenation and local blood volume in both vastus lateralis muscles during 3000-m race simulations in elite speed skaters on ice and the effects of leg compression on physiological, perceptual, and performance measures. Methods: Ten (6 female) elite ice speed skaters completed 2 on-ice trials with and without leg compression. Tissue oxygénation and local blood volume in both vastus lateralis muscles were assessed with near-infrared spectroscopy. Continuous measures of oxygen uptake, ventilation, heart rate, and velocity were conducted throughout the race simulations, as well as blood lactate concentration and ratings of perceived exertion before and after the trials. In addition, lap times were assessed. Results: The investigation of tissue oxygénation in both vastus lateralis muscles revealed an asymmetry (P < .00; effect size = 1.81) throughout the 3000-m race simulation. The application of leg compression did not affect oxygénation asymmetry (smallest P = .99; largest effect size = 0.31) or local blood volume (P = .33; 0.95). Lap times (P = .88; 0.43), velocity (P = .24; 0.84), oxygen uptake (P = .79; 0.10), ventilation (P = . 11 ; 0.59), heart rate (P = .21 ; 0.89), blood lactate concentration (P = .82; 0.59), and ratings of perceived exertion (P = .19; 1.01) were also unaffected by the different types of clothing. Conclusion: Elite ice speed skaters show an asymmetry in tissue oxygénation of both vastus lateralis muscles during 3000-m events remaining during the long gliding phases along the straight sections of the track. Based on the data, the authors conclude that there are no performance-enhancing benefits from wearing leg compression under a normal racing suit. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate whether upper-body compression affects power output and selected metabolic, cardio- respiratory, hemodynamic, and perceptual responses during three 3-min sessions of double-poling (DP) sprint. Method: Ten well-trained male athletes (25 ± 4 y, 180 ± 4 cm, 74.6 ± 3.2 kg) performed such sprints on a DP ski ergometer with and without a long-sleeved compression garment. Result: Mean power output was not affected by such compression (216 ± 25 W in both cases; P = 1.00, effect size [ES] = 0.00), although blood lactate concentration was lowered (P < .05, ES = 0.50-1.02). Blood gases (ES = 0.07-0.50), oxygen uptake (ES = 0.04-0.28), production of carbon dioxide (ES = 0.01-0.46), heart rate (ES = 0.00-0.21), stroke volume (ES = 0.33-0.81), and cardiac output (ES = 0.20-0.91) were also all unaffected by upper-body compression (best P = 1.00). This was also the case for changes in the tissue saturation index (ES = 0.45-1.17) and total blood content of hemoglobin (ES = 0.09-0.85), as well as ratings of perceived exertion (ES = 0.15-0.88; best P = .96). Conclusion: The authors conclude that the performance of well-trained athletes during 3 x 3-min DP sprints will not be enhanced by upper-body compression. [ABSTRACT FROM AUTHOR]

To assess original research addressing the effect of the application of compression clothing on sport performance and recovery after exercise, a computer-based literature research was performed in July 2011 using the electronic databases PubMed, MEDLINE, SPORTDiscus, and Web of Science. Studies examining the effect of compression clothing on endurance, strength and power, motor control, and physiological, psychological, and biomechanical parameters during or after exercise were included, and means and measures of variability of the outcome measures were recorded to estimate the effect size (Hedges g) and associated 95% confidence intervals for comparisons of experimental (compression) and control trials (noncompression). The characteristics of the compression clothing, participants, and study design were also extracted. The original research from peer-reviewed journals was examined using the Physiotherapy Evidence Database (PEDro) Scale. Results indicated small effect sizes for the application of compression clothing during exercise for short- duration sprints (10-60 m), vertical-jump height, extending time to exhaustion (such as running at VO2max or during incremental tests), and time-trial performance (3-60 min). When compression clothing was applied for recovery purposes after exercise, small to moderate effect sizes were observed in recovery of maximal strength and power, especially vertical-jump exercise; reductions in muscle swelling and perceived muscle pain; blood lactate removal; and increases in body temperature. These results suggest that the application of compression clothing may assist athletic performance and recovery in given situations with consideration of the effects magnitude and practical relevance. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of a repeated sprint training with multi-directional change-of-direction (COD) movements (RSmulti) compared to repeated shuttle sprints (RSS) on variables related to COD speed and reactive agility. Nineteen highly-trained male U15 soccer players were assigned into two groups performing either RSmulti or RSS. For both groups, each training session involved 20 repeated 15s sprints interspersed with 30 s recovery. With RSmulti the COD movements were randomized and performed in response to a visual stimulus, while the RSS involved predefined 180° COD movements. Before and following the six training sessions, performance in the Illinois agility test (IAT), COD speed in response to a visual stimulus, 20 m linear sprint time and vertical jumping height were assessed. Both groups improved their performance in the IAT (p < 0.01, ES = 1.13; p = 0.01, ES = 0.55). The COD speed in response to a visual stimulus improved with the RSmulti (p < 0.01, ES = 1.03), but not the RSS (p = 0.46, ES = 0.28). No differences were found for 20 m sprint time (P=0.73, ES = 0.07; p = 0.14, ES = 0.28) or vertical jumping height (p = 0.46, ES = 0.11; p = 0.29, ES = 0.12) for the RSmulti and RSS, respectively. In conclusion, performance in the IAT improved with the RSmulti as well as RSS. With the RSmulti however, the COD movements are performed in response to a visual stimulus, which may result in specific adaptations that improve COD speed and reactive agility in young highly trained soccer players. [ABSTRACT FROM AUTHOR]

Purpose: Repeated-sprint training in hypoxia (RSH) was recently shown to improve repeated-sprint ability (RSA) in cycling. This phenomenon is likely to reflect fiber type-dependent, compensatory vasodilation, and therefore, our hypothesis was that RSH is even more beneficial for activities involving upper body muscles, such as double poling during cross-country skiing. Methods: In a double-blinded fashion, 17 competitive cross-country skiers performed six sessions of repeated sprints (each consisting of four sets of five 10-s sprints, with 20-s intervals of recovery) either in normoxia (RSN, 300 m; FiO2, 20.9%; n = 8) or normobaric hypoxia (RSH, 3000 m; FiO2, 13.8 %; n = 9). Before (pre) and after (post) training, performance was evaluated with an RSA test (10-s all-out sprints-20-s recovery, until peak power output declined by 30%) and a simulated team sprint (team sprint, 3 x 3-min all-out with 3-min rest) on a double-poling ergometer. Triceps brachii oxygenation was measured by near-infrared spectroscopy. Results: From pretraining to posttraining, peak power output in the RSA was increased (P < 0.01) to the same extent (29% ±;13% vs 26% ±;18%, nonsignificant) in RSH and in RSN whereas the number of sprints performed was enhanced in RSH (10.9 ±;5.2 vs 17.1 ±;6.8, P < 0.01) but not in RSN (11.6 ±;5.3 vs 11.7 ±;4.3, nonsignificant). In addition, the amplitude in total hemoglobin variations during sprints throughout RSA rose more in RSH (P < 0.01). Similarly, the average power output during all team sprints improved by 11% ±;9% in RSH and 15% ±;7% in RSN. Conclusions: Our findings reveal greater improvement in the performance of repeated double-poling sprints, together with larger variations in the perfusion of upper body muscles in RSH compared with those in RSN. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to determine the acute responses of breathing oxygen-enriched air during the recovery periods of a simulated 3 x 3-min cross-country skiing team sprint competition at simulated low altitude. Methods: Eight well-trained male endurance athletes performed two 3 x 3-min team sprint simulations on a double-poling ergometer at simulated altitude set at ~ 1800 m. During the recovery periods between the 3 x 3-min sprints, all the athletes inhaled either hyperoxic (Fi02 = 1.00) or hypoxic (FiO2∼0.165) air in randomized and single-blind order. The mean total power output (Pmean tot) ar>d tne mean power output of each sprint (Pmean 1.2,3) were determined. Perceived exertion, capillary oxygen saturation of hemoglobin, partial pressure of oxygen, and blood lactate concentration were measured before and after all the sprints. Results: No differences in Pmean tot were found between hyperoxic (198.4 ± 27.1 W) and hypoxic (200.2 ± 28.0 W) recovery (f = 0.57, effect size [d] = 0.07). Pmean 1,2,3 (P> 0.90, d= 0.04-0.09) and RPE (P> 0.13, d= 0.02-0.63) did not differ between hyperoxic and hypoxic recovery. The partial pressure of oxygen (P< 0.01, d= 0.06-5.45) and oxygen saturation (P<0.01, d = 0.15-5.40) during hyperoxic recovery were higher than those during hypoxic recovery. The blood lactate concentration was also lower directly after the third sprint (P = 0.03, d = 0.54) with hyperoxic recovery. Conclusion: Results indicate that trained endurance athletes who inhale 100% oxygen during recovery periods in a cross-country skiing team sprint at low altitude do not exhibit enhanced performance despite the improvement in the key physiological variables of endurance performance. [ABSTRACT FROM AUTHOR]