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.
Paula J. Robson, Patrick J.D. Bouic and Kathryn H. Myburgh
Heather K. Neilson, Ruth Ullman, Paula J. Robson, Christine M. Friedenreich and Ilona Csizmadi
The qualitative attributes and quantitative measurement properties of physical activity questionnaires are equally important considerations in questionnaire appraisal, yet fundamental aspects such as question comprehension are not often described in the literature. Here we describe the use of cognitive interviewing to evaluate the Sedentary Time and Activity Reporting Questionnaire (STAR-Q), a self-administered questionnaire designed to assess overall activity energy expenditure and sedentary behavior.
Several rounds of one-on-one interviews were conducted by an interviewer trained in qualitative research methods. Interviewees included a convenience sample of volunteers and participants in the Tomorrow Project, a large cohort study in Alberta, Canada. Following each round of interviews the STAR-Q was revised and cognitively tested until saturation was achieved.
Six rounds of cognitive interviewing in 22 adults (5 males, 17 females) age 23−74 years, led to revisions involving 1) use of recall aids; 2) ambiguous terms; and 3) specific tasks, such as averaging across multiple routines, reporting time asleep and self-care, and reporting by activity domain.
Cognitive interviewing is a critical step in questionnaire development. Knowledge gained in this study led to revisions that improved respondent acceptability and comprehension of the STAR-Q and will complement ongoing validity testing.
Neil P. Walsh, Andrew K. Blannin, Nicolette C. Bishop, Paula J. Robson and Michael Gleeson
Recent studies have shown that neutrophils can utilize glutamine and that glutamine supplementation can improve neutrophil function in postoperative and burn patients. The present study investigated the influence of oral glutamine supplementation on stimulated neutrophil degranulation and oxidative burst activity following prolonged exercise. Subjects, 7 well-trained men, reported to the laboratory following an overnight fast and cycled for 2 hrs at 60%
Samantha K. Gill, Dean M. Allerton, Paula Ansley-Robson, Krystal Hemmings, Martin Cox and Ricardo J.S. Costa
The study aimed to determine if short-term high dose probiotic supplementation containing Lactobacillus casei (L.casei) attenuates the commonly reported exertional-heat stress (EHS) induced endotoxinaemia and cytokinaemia. Eight endurance trained male volunteers (mean± SD: age 26 ± 6 y, nude body mass 70.2 ± 8.8 kg, height 1.75 ± 0.05 m, VO2max 59 ± 5 ml·kg-1·min-1) completed a blinded randomized cross-over design, whereby oral ingestion of a commercially available probiotic beverage containing L.casei (volume equivalent for ×1011 colony forming units·day-1) (PRO) or placebo (PLA) was consumed for 7 consecutive days before exposure to EHS, which comprised of 2h running exercise at 60% VO2max in hot ambient conditions (34.0 °C and 32% RH). Blood samples were collected at baseline (7 days before EHS), pre-EHS, post-EHS (1 hr, 2 hr, 4 hr, and at 24 hr). Plasma samples were analyzed for gram-negative bacterial endotoxin, cytokine profile (IL-6, IL-1β, TNF-α, IFN-γ, IL-8, and IL-10) and plasma osmolality. Plasma osmolality did not differ between trials. Seven days of L.casei supplementation did not show significant changes in resting circulatory endotoxin concentration or plasma cytokine profile compared with PLA. A main effect of time was observed for IL-6, TNF-α, IL-10 and IL-8; whereby levels increased in response to EHS (p < .05). Relative to pre-EHS concentrations, higher plasma concentrations of endotoxin (p = .05), and a trend for higher plasma TNF-α concentration (p = .09) was observed on PRO compared with PLA throughout recovery. Short-term high dose supplementation of a probiotic beverage containing L.casei before EHS did not attenuate EHS induced endotoxaemia and cytokinaemia; nor is it more positively favorable over a placebo.
Joshua A. Nicholas, Geraldine Lo Siou, Brigid M. Lynch, Paula J. Robson, Christine M. Friedenreich and Ilona Csizmadi
Sedentary behavior has been proposed as a risk factor for obesity that is distinct from physical inactivity. This study aimed to examine the association between occupational sedentary behavior and obesity, and to determine if this association is independent of leisure-time physical activity (LTPA).
Fully employed participants enrolled between 2001 and 2008 to Alberta’s Tomorrow Project, a prospective cohort study in Alberta, Canada, were studied (n = 12,409). Associations between occupational sedentary behavior and waist circumference (WC), waist-to-hip ratio (WHR), and body mass index (BMI) were examined using multiple binary and multinomial logistic regressions.
In men, a positive association was observed between daily occupational sedentary hours and WC, WHR, BMI, and with high risk profiles that incorporated both BMI and WC (P < .01). Controlling for vigorous-intensity LTPA in all models strengthened associations between sedentary behavior and measures of obesity. In contrast, inverse associations were observed for occupational sedentary hours and WHR for women (P < .05).
In fully employed men, occupational sedentary behavior was positively associated with obesity risk that was not attenuated by physical activity. In women, an increase in obesity risk was not observed with sedentary behavior. Gender differences in the health effects of sedentary behavior require further study.