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Petros G. Botonis, Ioannis Malliaros, Gavriil G. Arsoniadis, Theodoros I. Platanou and Argyris G. Toubekis

Purpose: To examine the acute physiological responses and internal training load of long-interval swimming and water polo–specific drills in high-level water polo players. Methods: A total of 10 water polo players performed both a high-intensity swimming without ball (SW) with intensity corresponding to 90% of their maximum speed previously attained during a 300-m swimming test or a counterattack ball drill (CA). Both SW and CA conditions were designed to provide equal time exposure. Thus, 3 bouts of 4 minutes duration and a 3-minute passive rest were performed in each condition. The players’ physiological responses were assessed by continuous monitoring heart rate (HR) during CA and SW as well as by measuring blood lactate at the end of each condition. Rating of perceived exertion was recorded at the end of each bout. The Edwards summated HR zones were used to measure internal training load. Results: Both peak and mean HR were similar between SW and CA, and no difference was detected between conditions in the percentage time spent at 90% to 100% of HRpeak. Postexercise blood lactate (8.5 [4.1] vs 11.5 [1.9] mmol·L−1) and rating of perceived exertion (8.1 [0.8] vs 8.7 [0.5] a.u.) values were lower in CA compared with SW (P < .05). Conclusions: SW compared with CA showed similar cardiac stress but increased anaerobic metabolism activation and higher rating of perceived exertion. Either CA or SW may be both used in training practice as a means to effectively train physical conditioning of water polo players, whereas CA may also facilitate tactical preparation.

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Jordan L. Fox, Robert Stanton, Charli Sargent, Cody J. O’Grady and Aaron T. Scanlan

Purpose: To quantify and compare external and internal game workloads according to contextual factors (game outcome, game location, and score-line). Methods: Starting semiprofessional, male basketball players were monitored during 19 games. External (PlayerLoad and inertial movement analysis variables) and internal (summated-heart-rate-zones and rating of perceived exertion [RPE]) workload variables were collected for all games. Linear mixed-effect models and effect sizes were used to compare workload variables based on each of the contextual variables assessed. Results: The number of jumps, absolute and relative (in min−1) high-intensity accelerations and decelerations, and relative changes-of-direction were higher during losses, whereas session RPE was higher during wins. PlayerLoad the number of absolute and relative jumps, high-intensity accelerations, absolute and relative total decelerations, total changes-of-direction, summated-heart-rate-zones, session RPE, and RPE were higher during away games, whereas the number of relative high-intensity jumps was higher during home games. PlayerLoad, the number of high-intensity accelerations, total accelerations, absolute and relative decelerations, absolute and relative changes-of-direction, summated-heart-rate-zones, sRPE, and RPE were higher during balanced games, whereas the relative number of total and high-intensity jumps were higher during unbalanced games. Conclusions: Due to increased intensity, starting players may need additional recovery following losses. Given the increased external and internal workload volumes encountered during away games and balanced games, practitioners should closely monitor playing times during games. Monitoring playing times may help identify when players require additional recovery or reduced training volumes to avoid maladaptive responses across the in-season.

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Aaron T. Scanlan, Neal Wen, Joshua H. Guy, Nathan Elsworthy, Michele Lastella, David B. Pyne, Daniele Conte and Vincent J. Dalbo

Purpose: To examine correlations between peak force and impulse measures attained during the isometric midthigh pull (IMTP) and basketball-specific sprint and jump tests. Methods: Male, adolescent basketball players (N = 24) completed a battery of basketball-specific performance tests. Testing consisted of the IMTP (absolute and normalized peak force and impulse at 100 and 250 ms); 20-m sprint (time across 5, 10, and 20 m); countermovement jump (CMJ; absolute and normalized peak force and jump height); standing long jump (distance); and repeated lateral bound (distance). Correlation and regression analyses were conducted between IMTP measures and other attributes. Results: An almost perfect correlation was evident between absolute peak force attained during the IMTP and CMJ (r = .94, R 2 = 56%, P < .05). Moderate to very large correlations (P < .05) were observed between IMTP normalized peak force and 5-m sprint time (r = −.44, R 2 = 19%), 10-m sprint time (r = −.45, R 2 = 20%), absolute (r = .57, R 2 = 33%), normalized (r = .86, R 2 = 73%) CMJ peak force, and standing long-jump distance (r = .51, R 2 = 26%). Moderate to very large correlations were evident between impulse measures during the IMTP and 5-m sprint time (100 ms, r = −.40, R 2 = 16%, P > .05) and CMJ absolute peak force (100 ms, r = .73, R 2 = 54%; 250 ms, r = .68, R 2 = 47%; P < .05). Conclusions: The IMTP may be used to assess maximal and rapid force expression important across a range of basketball-specific movements.

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Kamila Grandolfi, Vandre Sosciarelli and Marcos Polito

Purpose: To compare performance in successive 1-repetition maximum (1RM) tests with the load known or unknown. Methods: Thirty-two resistance-trained men were randomly divided into 2 groups: load blinding (BLI; n = 16; age 28.1 [6.9] y, body mass 83.1 [11.5] kg, height 175.3 [5.8] cm) and load nonblinding (nBLI; n = 16; age 27.7 [4.1] y, body mass 83.2 [12.8] kg, height 178.7 [7.3] cm). The groups performed a 1RM test during 4 days (with an interval of 24–48 h) in the horizontal bench press with free weight. Results: In the BLI, there were no significant changes throughout the tests, with a difference of 1.6% between the first and fourth 1RM tests. In the nBLI, there was a significant interaction with time, and the values of the second (P = .03), third (P = .02), and fourth (P = .01) tests were higher than the first test; in addition, the fourth test was significantly higher than the second test (P = .02). The percentage difference between the last and first 1RM tests was 7.1%. The comparison between the groups demonstrated differences in the third (P = .04) and fourth (P = .02) tests with higher values in the nBLI. The intraclass correlation coefficient between the first and fourth 1RM tests was .93 for the BLI and .91 for the nBLI. Conclusion: BLI does not influence 1RM testing in the bench press exercise.

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Paul Comfort, Thomas Dos’Santos, Paul A. Jones, John J. McMahon, Timothy J. Suchomel, Caleb Bazyler and Michael H. Stone

Purpose: To determine the reliability of early force production (50, 100, 150, 200, and 250 ms) relative to peak force (PF) during an isometric mid-thigh pull and to assess the relationships between these variables. Methods: Male collegiate athletes (N = 29; age 21.1 [2.9] y, height 1.71 [0.07] m, body mass 71.3 [13.6] kg) performed isometric mid-thigh pulls during 2 separate testing sessions. Net PF and net force produced at each epoch were calculated. Within- and between-session reliabilities were determined using intraclass correlation coefficients and coefficient of variation percentages. In addition, Pearson correlation coefficients and coefficient of determination were calculated to examine the relationships between PF and time-specific force production. Results: Net PF and time-specific force demonstrated very high to almost perfect reliability both within and between sessions (intraclass correlation coefficients .82–.97; coefficient of variation percentages 0.35%–1.23%). Similarly, time-specific force expressed as a percentage of PF demonstrated very high to almost perfect reliability both within and between sessions (intraclass correlation coefficients .76–.86; coefficient of variation percentages 0.32%–2.51%). Strong to nearly perfect relationships (r = .615–.881) exist between net PF and time-specific net force, with relationships improving over longer epochs. Conclusion: Based on the smallest detectable difference, a change in force at 50 milliseconds expressed relative to PF > 10% and early force production (100, 150, 200, and 250 ms) expressed relative to PF of >2% should be considered meaningful. Expressing early force production as a percentage of PF is reliable and may provide greater insight into the adaptations to the previous training phase than PF alone.

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Daniel Bok and Igor Jukić

Purpose: To report creatine kinase ([CK]) responses during a soccer World Cup preparatory and first-leg period and to determine the influence of aerobic fitness on postmatch [CK] responses. Methods: Eleven national-team players were analyzed in this study. A lactate threshold test was performed during the first 3 d, whereas fingertip blood was drawn most mornings (21 out of 30 d) for [CK] measurements. One-way repeated-measures analysis of variance was used for determining the effect of time on [CK] measurements, whereas Pearson correlation coefficient was used for assessing associations between the changes in [CK] and velocities associated with blood lactate concentrations of 2 (v2) and 4 mmol·L−1 (v4). Results: Peak [CK] concentrations were consistently reached on the first day after the match with values of 474 (261), 520 (419), and 460 (126) U·L−1 but with no significant differences between them. [CK] concentrations returned to prematch values (331 [201] U·L−1) on the second day after the match. The change in [CK] concentration between prematch and postmatch day was largely correlated (r = .614, P = .044) with v2. Conclusions: Top-level soccer players display low levels of muscle damage during official tournaments, and they recover before the next match. Postmatch muscle damage is greater in players with higher aerobic endurance because this fitness quality enables them to execute high-intensity activities known to be a major contributor to muscle damage.

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Pedro L. Valenzuela, Guillermo Sánchez-Martínez, Elaia Torrontegi, Javier Vázquez-Carrión, Manuela González, Zigor Montalvo and Grégoire P. Millet

Purpose: Repeated-sprint training (RS) is commonly conducted in normoxia, but its completion with localized (blood-flow restriction [BFR]) or systemic hypoxia has been proven effective for performance enhancement. Yet, few studies have applied these types of RS sessions in racket sports. The authors aimed to determine the acute responses to these types of training in elite badminton players. Methods: Eight male elite badminton players participated in this randomized crossover study. They performed 3 on-court RS sessions, each consisting of 3 sets of 10 repetitions of 10-s badminton-specific movements in normoxia (RSN), systemic normobaric hypoxia (RSH, FiO2 = 14%), or with BFR (RS-BFR, 40% arterial occlusion pressure). Performance, perceptual (ie, rating of perceived exertion), and physiological (ie, pulse saturation, muscle oxygenation, blood lactate, creatine kinase, heart-rate variability) responses were measured after each set and up to 48 h postsession. Results: RS-BFR induced a greater performance impairment (lower distance and accelerations) and a higher local perceived exertion in the legs than RSN and RSH (P < .05), whereas greater overall fatigue was reported with RSH (P < .05). RSH induced a lower saturation (P < .001), but no differences were observed in muscle oxygenation between conditions. No differences in creatine kinase or heart-rate variability were observed at any time point (from baseline up to 48 h after the session). Conclusions: RS-BFR—and, to a lower extent, RSH—resulted in impaired performance and a higher perceived strain than RSN. However, these 2 hypoxic methods do not seem to induce a long-lasting (post 24–48 h) physiological stress in elite badminton players.

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Ida A. Heikura, Marc Quod, Nicki Strobel, Roger Palfreeman, Rita Civil and Louise M. Burke

Purpose: To assess energy and carbohydrate (CHO) availability and changes in blood hormones in 6 professional male cyclists over multiple single-day races. Methods: The authors collected weighed-food records, power-meter data, and morning body mass measurements across 8 d. CHO intakes were compared with contemporary guidelines. Energy availability (EA) was calculated as energy intake minus exercise energy expenditure, relative to fat-free mass (FFM). Skinfold thickness and blood metabolic and reproductive hormones were measured prestudy and poststudy. Statistical significance was defined as P ≤ .05. Results: Body mass (P = .11) or skinfold thickness (P = .75) did not change across time, despite alternate-day low EA (14 [9] vs 57 [10] kcal·kg−1 FFM·d−1, race vs rest days, respectively; P < .001). Cyclists with extremely low EA on race days (<10 kcal·kg−1 FFM·d−1; n = 2) experienced a trend toward decreased testosterone (−14%) and insulin-like growth factor 1 (−25%), despite being high EA (>46 kcal·kg−1 FFM·d−1) on days between. CHO intakes were significantly higher on race versus rest days (10.7 [1.3] vs 6.4 [0.8] g·kg−1·d−1, respectively; P < .001). The cyclists reached contemporary prerace fueling targets (3.4 [0.7] g·kg−1·3 h−1 CHO; P = .24), while the execution of CHO guidelines during race (51 [9] g·h−1; P = .048) and within acute (1.6 [0.5] g·kg−1·3 h−1; P = .002) and prolonged (7.4 [1.0] g·kg−1·24 h−1; P = .002) postrace recovery was poor. Conclusions: The authors are the first to report the day-by-day periodization of energy and CHO in a small sample of professional cyclists. They also examined the logistics of conducting a field study under stressful conditions in which major cooperation from the subjects and team management is needed. Their commentary around these challenges and possible solutions is a major novelty of the article.

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Owen Jeffries, Mark Waldron, Stephen D. Patterson and Brook Galna

Purpose: Regulation of power output during cycling encompasses the integration of internal and external demands to maximize performance. However, relatively little is known about variation in power output in response to the external demands of outdoor cycling. The authors compared the mean power output and the magnitude of power-output variability and structure during a 20-min time trial performed indoors and outdoors. Methods: Twenty male competitive cyclists (V˙O2max 60.4 [7.1] mL·kg−1·min−1) performed 2 randomized maximal 20-min time-trial tests: outdoors at a cycle-specific racing circuit and indoors on a laboratory-based electromagnetically braked training ergometer, 7 d apart. Power output was sampled at 1 Hz and collected on the same bike equipped with a portable power meter in both tests. Results: Twenty-minute time-trial performance indoor (280 [44] W) was not different from outdoor (284 [41] W) (P = .256), showing a strong correlation (r = .94; P < .001). Within-persons SD was greater outdoors (69 [21] W) than indoors (33 [10] W) (P < .001). Increased variability was observed across all frequencies in data from outdoor cycling compared with indoors (P < .001) except for the very slowest frequency bin (<0.0033 Hz, P = .930). Conclusions: The findings indicate a greater magnitude of variability in power output during cycling outdoors. This suggests that constraints imposed by the external environment lead to moderate- and high-frequency fluctuations in power output. Therefore, indoor testing protocols should be designed to reflect the external demands of cycling outdoors.

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Oliver Gonzalo-Skok, Alejandro Moreno-Azze, José Luis Arjol-Serrano, Julio Tous-Fajardo and Chris Bishop

Purpose: To compare the effects of performing different unilateral strength training interventions on unilateral and bilateral jumping performance and their related asymmetries in young soccer players. Methods: Forty-five young (U-17) male soccer players were randomly assigned to 3 eccentric overload training programs. The first group executed the same volume with both legs starting with the weaker leg (SVW, n = 15); the second group carried out double volume with the weaker leg and also starting with the weaker leg (DVW, n = 15); and the third group performed the same volume with both legs starting with the stronger leg (SVS, n = 15). Jumping-performance assessment included a single-leg horizontal jump test, a triple single-leg horizontal jump test, a bilateral countermovement jump (CMJ) test, and a unilateral CMJ test. Asymmetries were also analyzed in the unilateral jumping tests. Results: CMJ was improved (effect size [ES]: 0.27–0.48) and CMJ asymmetry was possibly reduced (ES: 0.08–0.24) in all groups. Substantial improvements were found in triple hop (ES: 0.52–0.71) in SVW and DVW, and triple-hop asymmetry was substantially decreased (ES: 0.88) in DVW. Between-groups analysis showed a substantially better performance in triple hop and horizontal hop with right leg in SVW and DVW compared with SVS. Conclusions: Unilateral strength training programs were shown to substantially improve bilateral jumping performance, while unilateral jumping was substantially enhanced in the groups that started the training session with the weaker leg. Finally, between-limbs asymmetries in the triple hop were mainly reduced through performing double volume with the weaker leg.