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Amelia J. Carr, Philo U. Saunders, Laura A. Garvican-Lewis, and Brent S. Vallance

Purpose: To quantify, for an elite-level racewalker, altitude training, heat acclimation and acclimatization, physiological data, and race performance from January 2007 to August 2008. Methods: The participant performed 7 blocks of altitude training: 2 “live high:train high” blocks at 1380 m (total = 22 d) and 5 simulated “live high:train low” blocks at 3000 m/600 m (total = 98 d). Prior to the 2007 World Championships and the 2008 Olympic Games, 2 heat-acclimation blocks of ~6 weeks were performed (1 session/week), with ∼2 weeks of heat acclimatization completed immediately prior to each 20-km event. Results: During the observation period, physiological testing included maximal oxygen uptake (VO2max, mL·kg−1·min−1), walking speed (km·h−1) at 4 mmol·L−1 blood lactate concentration [La], body mass (kg), and hemoglobin mass (g), and 12 × 20-km races and 2 × 50-km races were performed. The highest VO2max was 67.0 mL·kg−1·min−1 (August 2007), which improved 3.1% from the first measurement (64.9 mL·kg−1·min−1, June 2007). The highest percentage change in any physiological variable was 7.1%, for 4 mmol·L−1 [La] walking speed, improving from 14.1 (June 2007) to 15.1 km·h−1 (August 2007). Personal-best times for 20 km improved from (hh:mm:ss) 1:21:36 to 1:19:41 (2.4%) and from 3:55:08 to 3:39:27 (7.1%) in the 50-km event. The participant won Olympic bronze and silver medals in the 20- and 50-km, respectively. Conclusions: Elite racewalkers who regularly perform altitude training may benefit from periodized heat acclimation and acclimatization prior to major international competitions in the heat.

Open access

Joseph O.C. Coyne, Sophia Nimphius, Robert U. Newton, and G. Gregory Haff

Open access

Lorenzo Lolli, Alan M. Batterham, Gregory MacMillan, Warren Gregson, and Greg Atkinson

Open access

Jos J. de Koning

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Rachel McCormick, Brian Dawson, Marc Sim, Leanne Lester, Carmel Goodman, and Peter Peeling

The authors compared the effectiveness of two modes of daily iron supplementation in athletes with suboptimal iron stores: oral iron (PILL) versus transdermal iron (PATCH). Endurance-trained runners (nine males and 20 females), with serum ferritin concentrations <50 μg/L, supplemented with oral iron or iron patches for 8 weeks, in a parallel group study design. Serum ferritin was measured at baseline and fortnightly intervals. Hemoglobin mass and maximal oxygen consumption (V˙O2max) were measured preintervention and postintervention in PATCH. A linear mixed effects model was used to assess the effectiveness of each mode of supplementation on sFer. A repeated-measures analysis of variance was used to assess hemoglobin mass and V˙O2max outcomes in PATCH. There was a significant time effect (p < .001), sex effect (p = .013), and Time × Group interaction (p = .009) for sFer. At Week 6, PILL had significantly greater sFer compared with PATCH (15.27 μg/L greater in PILL; p = .019). Serum ferritin was 15.53 μg/L greater overall in males compared with females (p = .013). There were no significant differences in hemoglobin mass (p = .727) or V˙O2max (p = .929) preintervention to postintervention in PATCH. Finally, there were six complaints of severe gastrointestinal side effects in PILL and none in PATCH. Therefore, this study concluded that PILL effectively increased sFer in athletes with suboptimal iron stores, whereas PATCH showed no beneficial effects.

Open access

Emma L. Sweeney, Daniel J. Peart, Irene Kyza, Thomas Harkes, Jason G. Ellis, and Ian H. Walshe

Experimental sleep restriction (SR) has demonstrated reduced insulin sensitivity in healthy individuals. Exercise is well-known to be beneficial for metabolic health. A single bout of exercise has the capacity to increase insulin sensitivity for up to 2 days. Therefore, the current study aimed to determine if sprint interval exercise could attenuate the impairment in insulin sensitivity after one night of SR in healthy males. Nineteen males were recruited for this randomized crossover study which consisted of four conditions—control, SR, control plus exercise, and sleep restriction plus exercise. Time in bed was 8 hr (2300–0700) in the control conditions and 4 hr (0300–0700) in the SR conditions. Conditions were separated by a 1-week entraining period. Participants slept at home, and compliance was assessed using wrist actigraphy. Following the night of experimental sleep, participants either conducted sprint interval exercise or rested for the equivalent duration. An oral glucose tolerance test was then conducted. Blood samples were obtained at regular intervals for measurement of glucose and insulin. Insulin concentrations were higher in SR than control (p = .022). Late-phase insulin area under the curve was significantly lower in sleep restriction plus exercise than SR (862 ± 589 and 1,267 ± 558; p = .004). Glucose area under the curve was not different between conditions (p = .207). These findings suggest that exercise improves the late postprandial response following a single night of SR.