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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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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.

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Teun van Erp, Robert P. Lamberts, and Dajo Sanders

Purpose: This study evaluated the power profile of a top 5 result achieved in World Tour cycling races of varying types, namely: flat sprint finish, semi-mountain race with a sprint finish, semi-mountain race with uphill finish, and mountain races (MT). Methods: Power output data from 33 professional cyclists were collected between 2012 and 2019. This large data set was filtered so that it only included top 5 finishes in World Tour races (18 participants and 177 races). Each of these top 5 finishes were subsequently classified as flat sprint finish, semi-mountain race with uphill finish, semi-mountain race with a sprint finish, and MT based on set criteria. Maximal mean power output (MMP) for a wide range of durations (5 s to 60 min), expressed in both absolute (in Watts) and relative terms (in Watts per kilogram), were assessed for each race type. Result: Short-duration power outputs (<60 s), both in relative and in absolute terms, are of higher importance to be successful in flat sprint finish and semi-mountain race with a sprint finish. Longer-duration power outputs (≥3 min) are of higher importance to be successful in semi-mountain race with uphill finish and MT. In addition, relative power outputs of >10 minutes seem to be a key determining factor for success in MT. These race-type specific MMPs of importance (ie, short-duration MMPs for sprint finishes, longer-duration MMPs for races with more elevation gain) are performed at a wide range (80%–97%) of the cyclist’s personal best MMP. Conclusions: This study shows that the relative importance of certain points on the power–duration spectrum varies with different race types and provides insight into benchmarks for achieving a result in a World Tour cycling race.