The purpose of this study was to investigate differences in substrate oxidation between dextrose (DEX) and unmodified (UAMS) and acid/alcohol-modified (MAMS) cornstarches. Seven endurance-trained men (VO2peak = 59.1 ± 5.4 mL·kg−1·min−1) participated in 2 h of exercise (66.4% ± 3.3% VO2peak) 30 min after ingesting 1 g/kg body weight of the experimental carbohydrate or placebo (PLA). Plasma glucose and insulin were elevated after DEX (P < 0.05) compared with UAMS, MAMS, and PLA. Although MAMS and DEX raised carbohydrate oxidation rate through 90 min of exercise, only MAMS persisted throughout 120 min (P < 0.05 compared with all trials). Exogenous-carbohydrate oxidation rate was higher in DEX than in MAMS and UAMS until 90 min of exercise. Acid/alcohol modification resulted in augmented carbohydrate oxidation with a small, sustained increase in exogenous-carbohydrate oxidation rate. MAMS appears to be metabolizable and available for oxidation during exercise.
Neil M. Johannsen and Rick L. Sharp
John M. Schuna Jr., Daniel S. Hsia, Catrine Tudor-Locke and Neil M. Johannsen
Background: Active workstations offer the potential for augmenting energy expenditure (EE) in sedentary occupations. However, comparisons of EE during pedal and treadmill desk usage at self-selected intensities are lacking. Methods: A sample of 16 adult participants (8 men and 8 women; 33.9 [7.1] y, 22.5 [2.7] kg/m2) employed in sedentary occupations had their EE measured using indirect calorimetry during 4 conditions: (1) seated rest, (2) seated typing in a traditional office chair, (3) self-paced pedaling on a pedal desk while typing, and (4) self-paced walking on a treadmill desk while typing. Results: For men and women, self-paced pedal and treadmill desk typing significantly increased EE above seated typing (pedal desk: +1.20 to 1.28 kcal/min and treadmill desk: +1.43 to 1.93 kcal/min, P < .001). In men, treadmill desk typing (3.46 [0.19] kcal/min) elicited a significantly higher mean EE than pedal desk typing (2.73 [0.21] kcal/min, P < .001). No significant difference in EE was observed between treadmill desk typing (2.68 [0.19] kcal/min) and pedal desk typing among women (2.52 [0.21] kcal/min). Conclusions: Self-paced treadmill desk usage elicited significantly higher EE than self-paced pedal desk usage in men but not in women. Both pedal and treadmill desk usage at self-selected intensities elicited approximate 2-fold increases in EE above what would typically be expected during traditional seated office work.
Neil M. Johannsen, Zebblin M. Sullivan, Nicole R. Warnke, Ann L. Smiley-Oyen, Douglas S. King and Rick L. Sharp
To determine whether chicken noodle soup before exercise increases ad libitum water intake, fluid balance, and physical and cognitive performance compared with water.
Nine trained men (age 25 ± 3 yr, VO2peak 54.2 ± 5.1 ml · kg−1 · min−1; M ± SD) performed cycle exercise in the heat (wet bulb globe temperature = 25.9 ± 0.4 °C) for 90 min at 50% VO2peak, 45 min after ingesting 355 ml of either commercially available bottled water (WATER) or chicken noodle soup (SOUP). The same bottled water was allowed ad libitum throughout both trials. Participants then completed a time trial to finish a given amount of work (10 min at 90% VO2peak; n = 8). Cognitive performance was evaluated by the Stroop color–word task before, every 30 min during, and immediately after the time trial.
Ad libitum water intake throughout steady-state exercise was greater in SOUP than with WATER (1,435 ± 593 vs. 1,163 ± 427 g, respectively; p < .03). Total urine volume was similar in both trials (p = .13), resulting in a trend for greater water retention in SOUP than in WATER (87.7% ± 7.6% vs. 74.9% ± 21.7%, respectively; p = .09), possibly due to a change in free water clearance (–0.32 ± 1.22 vs. 0.51 ± 1.06 ml/min, respectively; p = .07). Fluid balance tended to be improved with SOUP (–106 ± 603 vs. –478 ± 594 g, p = .05). Likewise, change in plasma volume tended to be reduced in SOUP compared with WATER (p = .06). Only mild dehydration was achieved (<1%), and physical performance was not different between treatments (p = .77). The number of errors in the Stroop color–word task was lower in SOUP throughout the entire trial (treatment effect; p = .04).
SOUP before exercise increased ad libitum water intake and may alter kidney function.
S. Nicole Fearnbach, Neil M. Johannsen, Corby K. Martin, Peter T. Katzmarzyk, Robbie A. Beyl, Daniel S. Hsia, Owen T. Carmichael and Amanda E. Staiano
Objective: To conduct a preliminary assessment of the relationships between cardiorespiratory fitness, adiposity, and cardiometabolic health using gold standard measures in diverse youth ranging from overweight to severe obesity. Methods: Twenty of 30 participants (mean [SD]; age 13.2 [1.8] y, 55% female, 45% African American) met the criteria for VO2peak during a graded cycle ergometer test to volitional fatigue. The body composition was measured by dual-energy X-ray absorptiometry (percentage of body fat, fat mass index, and fat-free mass) and magnetic resonance imaging (abdominal visceral and subcutaneous [SAT] adipose tissue). The VO2peak was expressed relative to fat-free mass. Fasting lipid levels, glycemic biomarkers, and vital signs were examined individually and used in a composite cardiometabolic risk score. Accelerometer-measured physical activity and sedentary time were included as covariates. Results: VO2peak was negatively associated with abdominal SAT (r = −.49, P < .05), but not visceral adipose tissue or markers of cardiometabolic health. The association between SAT and VO2peak was partly explained by habitual sedentary time. Conclusions: We demonstrated a significant negative association between cardiorespiratory fitness and SAT in a diverse group of high-risk youth. The inclusion of rigorous, laboratory-based measures and youth with severe obesity extends the previous work in pediatric populations.