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Robyn L. Bowen, J. Harold Adams and Kathryn H. Myburgh

Purpose:

A 29-year-old elite adventure-race athlete presented with a 10-month history of nausea appearing during or after ultraendurance races. The athlete noted recent worsening of symptoms, including lightheadedness, dark rings under the eyes, and weakness as nausea became worse, and was unable to complete races. Possible diagnoses included dehydration or over hydration, renal damage, and gastrointestinal malfunction.

Methods:

The subject (S) and a case-control athlete (C) performed an 11-hour simulated race (field test) ending in the laboratory. Blood samples were drawn, and body mass and food and drink ingested were noted at regular intervals.

Results:

Symptoms were replicated in S, whose vomitus contained undigested solids consumed during exercise. Over 11 hours, fl uid loss was similar in S (9.6 L) and C (10.3 L), but fluid intake for S was 4.8 L versus 9.9 L for C. Body mass decreased 6% in S and 1.8% in C. S presented with elevated serum urea and creatinine before and after and elevated osmolality after the field test. A week after the fi eld test, creatinine clearance was low in S but not C (83 vs 160 mmol per 24-hour urine, respectively). S was instructed to increase fluid intake throughout the day, to match fluid lost during training, and to refrain from long races. After 2 months, his serum urea, creatinine, and osmolality were normal, and creatinine clearance improved to 133 mmol per 24-hour urine. He repeated the fi eld test and experienced no nausea.

Conclusions:

Nausea in ultraendurance athletes might be an early symptom of chronic but reversible renal strain or insensitivity to high osmolality.

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Paula J. Robson, Patrick J.D. Bouic and Kathryn H. Myburgh

The influence of an antioxidant vitamin supplement on immune cell response to prolonged exercise was determined using a randomized, double-blind, placebo-controlled, cross-over study. Twelve healthy endurance subjects (n = 6 male, n = 6 female; mean ± SD for age, 30.1 ± 6.2 yr; height, 1.76 ± 7 m; body mass, 72.2 ± 10.2 kg; VO2max, 63.7 ± 12 ml · kg–1 · min–1) participated in the study. Following a 3-week period during which subjects ingested a multivitamin and -mineral complex sufficient to meet the recommended daily allowance, they took either a placebo or an antioxidant vitamin supplement (containing 18 mg β-carotene, 900 mg vitamin C, and 90 mg vitamin E) for 7 days prior to a 2-h treadmill run at 65% VO2max. Blood samples were drawn prior to and immediately following exercise. These were analyzed for neutrophil oxidative burst activity, cortisol and glucose concentrations, and white blood cell counts, as well as serum anti-oxidant vitamin concentrations. Plasma vitamin C, vitamin E, and β-carotene concentrations significantly increased following 7-day supplementation (p < .05). In comparison to the placebo group, neutrophil oxidative burst was significantly higher following exercise (p < .05), but no differences were found in any other parameter following the 7-day supplementation period. Although the impact of exercise on neutrophil function is multifactorial, our data suggest that antioxidant supplementation may be of benefit to endurance athletes for the maintenance of this particular function of the innate immune system following the 7-day supplementation period.

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Laura Capranica, Maria Francesca Piacentini, Shona Halson, Kathryn H. Myburgh, Etsuko Ogasawara and Mindy Millard-Stafford

Sport is recognized as playing a relevant societal role to promote education, health, intercultural dialogue, and the individual development, regardless of an individual’s gender, race, age, ability, religion, political affiliation, sexual orientation, and socioeconomic background. Yet, it was not until the 2012 Summer Olympic Games in London that every country’s delegation included a female competitor. The gender gap in sport, although closing, remains, due to biological differences affecting performance, but it is also influenced by reduced opportunity and sociopolitical factors that influence full female participation across a range of sports around the world. Until the cultural environment is equitable, scientific discussion related to physiological differences using methods that examine progression in male and female world-record performances is limited. This commentary is intended to provide a forum to discuss issues underlying gender differences in sport performance from a global perspective and acknowledge the influence of cultural and sociopolitical factors that continue to ultimately affect female performance.

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Kathryn H. Myburgh, Claire Berman, Illana Novick, Timothy D. Noakes and Estelle V. Lambert

We studied 21 ballet dancers aged 19.4 ± 1.4 years, hypothesizing that undernu-trition was a major factor in menstrual irregularity in this population. Menstrual history was determined by questionnaire. Eight dancers had always been regular (R). Thirteen subjects had a history of menstrual irregularity (HI). Of these, 2 were currently regularly menstruating, 3 had short cycles, 6 were oligomenorrheic, and 2 were amenorrheic. Subjects completed a weighed dietary record and an Eating Attitudes Test (EAT). The following physiological parameters were measured: body composition by anthropometry, resting metabolic rate (RMR) by open-circuit indirect calorimetry, and serum thyroid hormone concentrations by radioimmunoassay. R subjects had significantly higher RMR than HI subjects. Also, HI subjects had lower RMR than predicted by fat-free mass, compared to the R subjects. Neitherreported energy intake nor serum thyroid hormone concentrations were different between R and HI subjects. EAT scores varied and were not different between groups. We concluded that in ballet dancers, low RMR is more strongly associated with menstrual irregularity than is currentreported energy intake or serum thyroid hormone concentrations.