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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.

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Pierpaolo Sansone, Alessandro Ceravolo, and Antonio Tessitore

Purpose: To quantify external, internal, and perceived training loads and their relationships in youth basketball players across different playing positions. Methods: Fourteen regional-level youth male players (age: 15.2 [0.3] y) were monitored during team-based training sessions across 10 in-season weeks. The players were monitored with BioHarness-3 devices, to measure external (Impulse Load, in Newtons per second) and internal (summated-heart-rate zones [SHRZ], in arbitrary units [AU]) loads, and with the session rating of perceived exertion (sRPE, in AU) method to quantify perceived training load. Multiple linear mixed models were performed to compare training loads between playing positions (backcourt and frontcourt). Repeated-measures correlations were performed to assess the relationships between the load models, for all players and within playing positions. Results: External load (backcourt: 13,599 [2260] N·s; frontcourt: 14,934 [2173] N·s) and sRPE (backcourt: 345 [132] AU; frontcourt: 505 [158] AU) were higher in the frontcourt (P < .05, effect size: moderate), while SHRZ was similar between positions (backcourt: 239 [45] AU; frontcourt: 247 [43] AU) (P > .05; effect size: trivial). The correlations were as follows: large between the external load and SHRZ (r = .57, P < .001), moderate between SHRZ and sRPE (r = .45, P < .001), and small between the external load and sRPE (r = .26, P = .02). The correlation magnitudes were equivalent for external load–SHRZ (large) and SHRZ–sRPE (moderate) across positions, but different for the external load–sRPE correlation (small in backcourt; moderate in frontcourt). Conclusions: In youth basketball, small–large commonalities were found between the training dose (external load) and players’ responses (internal and perceived loads). Practitioners should carefully manage frontcourt players’ training loads because they accumulate greater external and perceived loads than backcourt  players do.

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Suzanna Russell, David G. Jenkins, Shona L. Halson, Laura E. Juliff, Mark J. Connick, and Vincent G. Kelly

Purpose: Mental fatigue is emerging as an important consideration for elite sporting performance, yet it is rarely monitored. The present study assessed changes in mental fatigue in professional team-sport athletes across 2 seasons and examined the relationship between mental fatigue and other athlete self-report measures of well-being. Methods: Elite netballers contracted to all teams competing in Australia’s premier professional netball competition during the 2018 and 2019 seasons (N = 154) participated. Using 5-point Likert scales, mental fatigue, fatigue (physical), tiredness, sleep quality, stress, mood, and motivation were assessed daily across 2 seasons composed of 14 round and finals series. Results: The ratings of mental fatigue significantly changed during both seasons. In 2018, lower ratings of mental fatigue were reported in round 1 versus 3, 4, 6, 8, and 14; round 7 versus 6; and round 6 versus 10 (P < .05). In 2019, lower ratings of mental fatigue were identified for round 1 versus 3, 9, 10 to 14, and semifinal; round 2 versus 10 to 13; and 5 versus 10 to 12 (P < .05). Ordinal regression revealed significant differences between mental fatigue and physical fatigue (P < .001), tiredness (P < .001), stress (P < .001), mood (P < .001), and motivation (P < .05). Conclusions: The present study found mental fatigue to significantly fluctuate across a season in elite netballers. Moreover, perceived mental fatigue differed from physical fatigue, tiredness, stress, mood, and motivation. The data impress the need for mental fatigue to be included as an independent measure of athlete well-being. Monitoring of mental fatigue can allow practitioners to implement strategies to manage its influence on performance.

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Fernando G. Beltrami, Christian Froyd, Alexis R. Mauger, Alan J. Metcalfe, and Timothy D. Noakes

Objective: To investigate whether a cycling test based on decremental loads (DEC) could elicit higher maximal oxygen uptake (V˙O2max) values compared with an incremental test (INC). Design: Nineteen well-trained individuals performed an INC and a DEC test on a single day, in randomized order. Methods: During INC, the load was increased by 20 W·min−1 until task failure. During DEC, the load started at 20 W higher than the peak load achieved during INC (familiarization trial) and was progressively decreased. Gas exchange and electromyography (EMG) activity (n = 11) from 4 lower-limb muscles were monitored throughout the tests. Physiological and EMG data measured at V˙O2max were compared between the 2 protocols using paired t tests. Results: V˙O2max during the DEC was 3.0% (5.9%) higher than during INC (range 94%–116%; P = .01), in spite of a lower power output (−21 [20] W, P < .001) at V˙O2max. Pulmonary ventilation (P = .036) and breathing rate (P = .023) were also higher during DEC. EMG activity measured at V˙O2max was not different between tests, despite the lower output during DEC. Conclusions: A DEC exercise test produces higher V˙O2max in cycling compared with an INC test, which was accompanied by higher pulmonary ventilation and similar EMG activity. The additional O2 uptake during DEC might be related to extra work performed either by the respiratory muscles and/or the less oxidatively efficient leg muscles.

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Jan Gajdošík, Jirˇí Baláš, Dominika Krupková, Lukáš Psohlavec, and Nick Draper

Purpose: Although sport climbing is a self-paced whole-body activity, speed varies with climbing style, and the effect of this on systemic and localized oxygen responses is not well understood. Therefore, the aim of the present study was to determine muscle and pulmonary oxygen responses during submaximal climbing at differing speeds of ascent. Methods: Thirty-two intermediate and advanced sport climbers completed three 4-minute-long ascents of the same route at 4, 6, and 9 m·min−1 on a motorized climbing ergometer (treadwall) on separate laboratory visits. Gas analysis and near-infrared spectroscopy were used to determine systemic oxygen uptake (V˙O2) and muscle oxygen saturation (StO2) of the flexor digitorum profundus. Results: Increases in ascent speed of 1 m·min−1 led to increases of V˙O2 by 2.4 mL·kg−1·min−1 (95% CI, 2.1 to 2.8 mL·kg−1·min−1) and decreases in StO2 by −1.3% (95% CI, 1.9% to −0.7%). There was a significant interaction of climbing ability and speed for StO2 (P < .001, ηp2=.224). The results revealed that the decrease of StO2 was present for intermediate but not advanced climbers. Conclusions: In this study, the results suggest that V˙O2 demand during climbing was largely determined by climbing speed; however, the ability level of the climber appeared to mitigate StO2 at a cellular level. Coaches and instructors may prescribe climbing ascents with elevated speed to improve generalized cardiorespiratory fitness. To stimulate localized aerobic capacity, however, climbers should perhaps increase the intensity of training ascents through the manipulation of wall angle or reduction of hold size.

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Geoffrey M. Minett, Valentin Fels-Camilleri, Joshua J. Bon, Franco M. Impellizzeri, and David N. Borg

Purpose: This study aimed to examine the effect of peer presence on session rating of perceived exertion (RPE) responses. Method: Fourteen males, with mean (SD) age 22.4 (3.9) years, peak oxygen uptake 48.0 (6.6) mL·kg−1·min−1, and peak power output 330 (44) W, completed an incremental cycling test and 3 identical experimental sessions, in groups of 4 or 5. Experimental sessions involved 24 minutes of cycling, whereby the work rate alternated between 40% and 70% peak power output every 3 minutes. During cycling, heart rate was collected every 3 minutes, and session-RPE was recorded 10 minutes after cycling, in 3 communication contexts: in written form unaccompanied (intrapersonal communication), verbally by the researcher only (interpersonal communication), and in the presence of the training group. Session-RPE was analyzed using ordinal regression and heart rate using a linear mixed-effects model, with models fit in a Bayesian framework. Results: Session-RPE was voted higher when collected in the group’s presence compared with when written (odds ratio = 4.26, 95% credible interval = 1.27–14.73). On average, the posterior probability that session-RPE was higher in the group setting than when written was .53. Session-RPE was not different between the group and verbal, or verbal and written collection contexts. Conclusions: This study suggests that contextual psychosocial inputs influence session-RPE and highlights the importance of session-RPE users controlling the measurement environment when collecting votes.