Alannah K.A. McKay, Peter Peeling, David B. Pyne, Nicolin Tee, Marijke Welveart, Ida A. Heikura, Avish P. Sharma, Jamie Whitfield, Megan L. Ross, Rachel P.L. van Swelm, Coby M. Laarakkers, and Louise M. Burke
This study implemented a 2-week high carbohydrate (CHO) diet intended to maximize CHO oxidation rates and examined the iron-regulatory response to a 26-km race walking effort. Twenty international-level, male race walkers were assigned to either a novel high CHO diet (MAX = 10 g/kg body mass CHO daily) inclusive of gut-training strategies, or a moderate CHO control diet (CON = 6 g/kg body mass CHO daily) for a 2-week training period. The athletes completed a 26-km race walking test protocol before and after the dietary intervention. Venous blood samples were collected pre-, post-, and 3 hr postexercise and measured for serum ferritin, interleukin-6, and hepcidin-25 concentrations. Similar decreases in serum ferritin (17–23%) occurred postintervention in MAX and CON. At the baseline, CON had a greater postexercise increase in interleukin-6 levels after 26 km of walking (20.1-fold, 95% CI [9.2, 35.7]) compared with MAX (10.2-fold, 95% CI [3.7, 18.7]). A similar finding was evident for hepcidin levels 3 hr postexercise (CON = 10.8-fold, 95% CI [4.8, 21.2]; MAX = 8.8-fold, 95% CI [3.9, 16.4]). Postintervention, there were no substantial differences in the interleukin-6 response (CON = 13.6-fold, 95% CI [9.2, 20.5]; MAX = 11.2-fold, 95% CI [6.5, 21.3]) or hepcidin levels (CON = 7.1-fold, 95% CI [2.1, 15.4]; MAX = 6.3-fold, 95% CI [1.8, 14.6]) between the dietary groups. Higher resting serum ferritin (p = .004) and hotter trial ambient temperatures (p = .014) were associated with greater hepcidin levels 3 hr postexercise. Very high CHO diets employed by endurance athletes to increase CHO oxidation have little impact on iron regulation in elite athletes. It appears that variations in serum ferritin concentration and ambient temperature, rather than dietary CHO, are associated with increased hepcidin concentrations 3 hr postexercise.
Jonne A. Kapteijns, Kevin Caen, Maarten Lievens, Jan G. Bourgois, and Jan Boone
Purpose: To determine if there is a link between the demands of competitive game activity and performance profiles of elite female field hockey players. Methods: Global positioning systems (GPS) were used to quantify running performance of elite female field hockey players (N = 20) during 26 competitive games. Performance profiles were assessed at 2 time points (preseason and midseason) for 2 competitive seasons. A battery of anthropometric and performance field-based tests (30–15 intermittent fitness test, incremental run test, 10–30-m speed test, T test, and vertical jump test) were used to determine the performance profiles of the players. Results: Players covered a mean total distance of 5384 (835) m, of which 19% was spent at high intensities (zone 5: 796  m; zone 6: 274  m). Forwards covered the lowest mean total distance (estimated marginal means 4586 m; 95% confidence interval, 4275–4897), whereas work rate was higher in forwards compared with midfielders (P = .006, d = 0.43) and central defenders (P = .001, d = 1.41). Players showed an improvement in body composition and anaerobic performance from preseason to midseason. Aerobic performance capacity (maximal oxygen uptake and speed at the 4-mM lactate threshold) was positively correlated with high-intensity activities. Conclusions: There is a clear relationship between running performance and aerobic performance profiles in elite female hockey players. These results highlight the importance of a well-developed aerobic performance capacity in order to maintain a high performance level during hockey games.
Thomas Haugen, Will Hopkins, Felix Breitschädel, Gøran Paulsen, and Paul Solberg
Purpose: To determine if generic off-ice physical fitness tests can provide useful predictions of ice hockey players’ match performance. Methods: Approximately 40 to 60 defenders and 70 to 100 forwards from the Norwegian male upper ice hockey league were tested for strength (1-repetition maximum in squat and bench press), power (40-m sprint and countermovement jump), and endurance (hanging sit-ups, chins, and 3000-m run) annually at the end of every preseason period between 2008 and 2017. Measures of match performance were each player’s season mean counts per match of assists, points, goals, penalty minutes, and plus-minus score. Results: Overall, match performance measures displayed trivial to small correlations with the fitness tests. More specifically, points per game had at most small correlations with measures of strength (range, approximately −0.2 to 0.3), speed (approximately −0.2 to 0.3), and endurance (approximately −0.1 to 0.3). After adjustments for age that showed moderate to large correlations with player match performance, multiple-regression analyses of each test measure still provided some predictability among players of the same age. However, players selected for the national team had substantially better mean scores for most tests and match performance measures than those not selected, with a moderate to large difference for age, 1-repetition maximum squat, and 1-repetition maximum bench press. Conclusions: Fitness tests had only marginal utility for predicting match performance in Norwegian hockey players, but those selected into the national team had better general fitness.
Erica H. Gavel, Heather M. Logan-Sprenger, Joshua Good, Ira Jacobs, and Scott G. Thomas
Purpose: The effects of menthol (MEN) mouth rinse (MR) on performance, physiological, and perceptual variables in female cyclists during a 30-km independent time trial (ITT) were tested. Methods: The participants (n = 9) cycled for 30 km in hot conditions (30°C [0.6°C], 70% [1%] relative humidity, 12  km/h wind speed) on 2 test occasions: with a placebo MR and with MEN MR. Handgrip and a 5-second sprint were measured before, following the first MR, and after the ITT. Ratings of perceived exertion Borg 6 to 20, thermal sensation, and thermal pleasantness were recorded every 5 km. Core temperature and heart rate were recorded throughout. Results: The ITT performance significantly improved with MEN MR by 2.3% (2.7%) relative to the placebo (62.6 [5.7] vs 64.0 [4.9] min P = .034; d = 0.85; 95% confidence interval, 0.14 to 2.8 min). The average power output was significantly higher in the MEN trial (P = .031; d = 0.87; 95% confidence interval, 0.9 to 15.0 W). No significant interaction of time and MR for handgrip (P = .581, η 2 = .04) or sprint was observed (P = .365, η 2 = .103). Core temperature, heart rate, ratings of perceived exertion, and thermal sensation did not significantly differ between trials at set distances (P > .05). Pleasantness significantly differed between the placebo and MEN only at 5 km, with no differences at other TT distances. Conclusion: These results suggest that a nonthermal cooling agent can improve 30-km ITT performance in female cyclists, although the improved performance with MEN MR is not due to altered thermal perception.
Jordan L. Fox, Jesse Green, and Aaron T. Scanlan
Purpose: To compare peak and average intensities encountered during winning and losing game quarters in basketball players. Methods: Eight semiprofessional male basketball players (age = 23.1 [3.8] y) were monitored during all games (N = 18) over 1 competitive season. The average intensities attained in each quarter were determined using microsensors and heart-rate monitors to derive relative values (per minute) for the following variables: PlayerLoad, frequency of high-intensity and total accelerations, decelerations, changes of direction, jumps, and total inertial movement analysis events combined, as well as modified summated-heart-rate-zones workload. The peak intensities reached in each quarter were determined using microsensors and reported as PlayerLoad per minute over 15-second, 30-second, 1-minute, 2-minute, 3-minute, 4-minute, and 5-minute sample durations. Linear mixed models and effect sizes were used to compare intensity variables between winning and losing game quarters. Results: Nonsignificant (P > .05), unclear–small differences were evident between winning and losing game quarters in all variables. Conclusions: During winning and losing game quarters, peak and average intensities were similar. Consequently, factors other than the intensity of effort applied during games may underpin team success in individual game quarters and therefore warrant further investigation.
Javier Yanci, Daniel Castillo, Aitor Iturricastillo, Astrid Aracama, Alba Roldan, and Raúl Reina
Purpose: The objectives of this study were to analyze whether there were differences among para-footballers with different types and degrees of brain impairment (ie, bilateral spasticity, athetosis/ataxia, unilateral spasticity, minimum impairment criteria, or no impairment) in performing 3 football-specific tests requiring ball dribbling, to analyze whether there was an association among the results obtained in the 3 tests, and to determine whether the performance in the tests was associated with competitive level, level of training, or years’ experience in para-footballers with cerebral palsy (CP). Methods: A total of 123 footballers took part in the study, 87 of whom were footballers with CP and 36 who were without impairment. Both groups were assessed in 3 football-specific tests (Stop and Go, Turning and Dribbling, and the Illinois Agility Test). Results: The results showed that the footballers without impairment recorded a better performance in all tests (P < .01) in comparison with the CP players. No significant differences in test performance were observed among the CP players from different competitive levels. However, significant differences (P < .01) were observed between players with diplegia or athetosis/ataxia compared with players with hemiplegia or minimum impairment level. Performance in the tests did not correlate with years of football experience, weekly strength training sessions, or specific football training in the footballers with CP (P = .12–.95). Conclusions: These findings suggest the possible inclusion of these tests in the classification process for footballers with CP because they discriminate among functional classes and are resistant to training and competitive level.
Craig Thomas, Helen Jones, Craig Whitworth-Turner, and Julien Louis
Purpose: (1) To compare the sleep of female players from a professional soccer team to nonathlete controls across an in-season week and (2) to compare the sleep of core and fringe players from the same team on the night after a match to training nights. Methods: Using an observational design, 18 professional female soccer players and 18 female nonathlete controls were monitored for their sleep via wristwatch actigraphy across 1 week. Independent-sample t tests and Mann–Whitney U tests were performed to compare sleep between groups, while an analysis of variance compared sleep on training nights to the night after a match. Results: Soccer players had significantly greater sleep duration than nonathlete controls (+38 min; P = .009; d: 0.92), which may have resulted from an earlier bedtime (−00:31 h:min; P = .047; d: 0.70). The soccer players also had less intraindividual variation in bedtime than nonathletes (−00:08 h:min; P = .023; r: .38). Despite this, sleep-onset latency was significantly longer among soccer players (+8 min; P = .032; d: 0.78). On the night after a match, sleep duration of core players was significantly lower than on training nights (−49 min; P = .010; d: 0.77). In fringe players, there was no significant difference between nights for any sleep characteristic. Conclusions: During the in-season period, sleep duration of professional female soccer players is greater than nonathlete controls. However, the night after a match challenges the sleep of players with more match involvement and warrants priority of sleep hygiene strategies.
Vicky L. Goosey-Tolfrey, Sonja de Groot, Keith Tolfrey, and Tom A.W. Paulson
Purpose: To confirm whether peak aerobic capacity determined during laboratory testing could be replicated during an on-court field-based test in wheelchair rugby players. Methods: Sixteen wheelchair rugby players performed an incremental speed-based peak oxygen uptake (