Michael E. Holmstrup

Multiple short bouts of exercise over 12-h period reduce glucose excursions more than an energy-matched single bout of exercise.

OBJECTIVE Long, uninterrupted bouts of sedentary behavior are thought to negatively influence postprandial glucose and insulin concentrations. We examined the effects of a 1-h bout of morning exercise versus intermittent walking bouts of short duration on glucose excursions and insulin secretion over 12-h. MATERIALS/METHODS Eleven young, obese individuals (18-35 years, BMI>30kg/m(2)) with impaired glucose tolerance were studied on three 12-h study days: 1) sedentary behavior (SED); 2) sedentary behavior with 1-h morning exercise (EX) at 60%-65% VO2peak; and 3) sedentary behavior with 12-hourly, 5-min intervals of exercise (INT) at 60%-65% VO2peak. Meals (1046kJ/meal) were provided every 2-h. Blood samples were collected every 10 min and measured for glucose, insulin, and c-peptide concentrations. RESULTS Glucose iAUC (12-h) was attenuated in the INT and SED conditions compared to the EX condition (P<0.05). Glucose concentrations were higher in the EX compared to the SED condition for ~150min (20% of the study day), and comparison of the EX-INT study days revealed that glucose concentrations were greater for~240min (~1/3 of the 12-hday). In the SED condition, the 12-h insulin iAUC was ~15% higher (P<0.05) compared to the INT and EX conditions. Insulin production rate was found to increase ~20% with INT exercise vs. the SED and EX condition (P<0.05). CONCLUSIONS Short, frequent periods of exercise attenuated glucose excursions and insulin concentrations in obese individuals to a greater degree than an equal amount of exercise performed continuously in the morning.

Satiety, but not total PYY, is increased with continuous and intermittent exercise

This study determined the hormonal and subjective appetite responses to exercise (1‐h continuous versus intermittent exercise throughout the day) in obese individuals.

Assessment of endothelial function and blood metabolite status following acute ingestion of a fructose-containing beverage

Aim:  Fructose intake has increased concurrent with sugar intake and this increase has been implicated in contributing to the development of metabolic syndrome risk factors. Recent evidence suggests a role for uric acid (UA) as a potential mediator via suppression of nitric oxide (NO) bioavailability. The aim of this study was to explore this hypothesis by measuring changes in UA concentration and systemic NO bioavailability as well as endothelial function in response to acute ingestion of a glucose‐fructose beverage.

Do Overweight and Obese Individuals Select a “Moderate Intensity” Workload When Asked to Do So?

The purpose of this study was (1) to determine if overweight/obese individuals (age 26–50 y) would self-select moderate exercise intensity when asked to do so and (2) to determine how this self-selected workload compared to exercising at a workload (60% peak aerobic capacity) that is known to provide cardioprotective health benefits. Oxygen consumption (VO2) and energy expenditure were measured in 33 men/women (BMI ≥ 27 kg/m2) who completed two 30 min walking bouts: (1) self-selected walking pace on an indoor track and (2) prescribed exercise pace (60% VO2 peak) on a treadmill. The data revealed that (1) the prescribed intensity was 6% higher than the self-selected pace and elicited a higher energy expenditure (P < 0.05) than the self-selected pace (+83 kJ); (2) overweight subjects walked at a slightly lower percentage of VO2 peak than the obese subjects (P < 0.05); (3) men walked at a lower percentage of VO2 peak than the women (P < 0.05). In conclusion when asked to walk at a moderate intensity, overweight/obese individuals tended to select a lower workload in the “moderate intensity” range which could be maintained for 30 min; however, a higher intensity which would be more cardioprotective could not be maintained for 30 min by most individuals.

Caloric estimation bias of realistic meal and beverage preparations

This study was undertaken to characterize caloric estimation bias in realistic meal and beverage preparations of varied size and nutritional value. Differences in the estimation bias of meals and beverages were determined in relation to sex and weight status (body mass index and percent body fat). In general, most subjects were inaccurate in caloric estimation. Subjects were more accurate when estimating larger versus smaller, and unhealthy versus healthy realistic, home-style food items. Accurate prediction of solid foods was not related to accurate beverage prediction. In addition to the size of food items, the healthfulness and form of calories are predictors of caloric estimation accuracy.

An acute bout of aerobic exercise alters interarm systolic blood pressure difference

Background Clinically, when a difference of at least 10 mmHg in systolic blood pressure (SBP) between arms exists, it is identified as an interarm systolic blood pressure difference (ISBPD). At rest, ISBPD is linked with hypertension, peripheral vascular disease, and increased premature mortality. Exercise may reveal underlying cardiovascular pathologies otherwise absent at rest. However, there have been no investigations to examine the effect of exercise on ISBPD. Aim The aim of this investigation was to determine whether exercise may alter ISBPD when detected at rest or reveal ISBPD when it was not observed in the resting condition. Methods An experienced investigator sequentially measured SBP using standard auscultation in each arm (alternating order) in 85 normotensive individuals (22±6 years, 39 male, 46 female). ISBPD was quantified before exercise (PRE). Participants then completed a three-stage protocol on a cycle ergometer. A cadence of 50 rpm was maintained at a workload of 3 (EX-3; light) and 6 (EX-6; moderate) METS and during an active recovery (REC). At each stage, SBP was measured upon achieving steady-state heart rate. A logistic regression analysis was used to determine the change in odds ratio of ISBPD when exposed to exercise. Results Thirteen percent (n=11) of patients presented with ISBPD during PRE and the degree of ISBPD was lower (3.81 mmHg; P<0.05) in REC than PRE. In individuals who did not present with ISBPD during PRE (n=74), progression from EX-3 to EX-6 significantly increased the odds of developing ISBPD (4.31; P<0.05). Conclusion In individuals with ISBPD at PRE, active recovery from exercise attenuated the difference between interarm SBP. Moderate-intensity exercise resulted in ISBPD not otherwise present at rest.