Muscle Glycogen Utilization during Exercise after Ingestion of Alcohol.

PURPOSE: Ingested ethanol (EtOH) is metabolized gastrically and hepatically, which may influence resting and exercise metabolism. Previous exercise studies have provided EtOH intravenously rather than orally, altering the metabolic effects of EtOH. No studies to date have investigated the effects of EtOH ingestion on systemic and peripheral (e.g., skeletal muscle) exercise metabolism. METHODS: Eight men (mean ± SD; age = 24 ± 5 yr, body mass = 76.7 ± 5.6 kg, height = 1.80 ± 0.04 m, V˙O2peak = 4.1 ± 0.2 L·min) performed two bouts of fasted cycling exercise at 55% V˙O2peak for 2 h, with (EtOH) and without (control) prior ingestion of EtOH 1 h and immediately before exercise (total dose = 0.1 g·kg lean body mass·h; 30.2 ± 1.1 g 40% ABV Vodka; fed in two equal boluses) in a randomized order, separated by 7-10 d. RESULTS: Muscle glycogen use during exercise was not different between conditions (mean [normalized 95% confidence interval]; EtOH, 229 [156-302] mmol·kg dm, vs control, 258 [185-331] mmol·kg dm; P = 0.67). Mean plasma glucose concentrations during exercise were similar (control, 5.26 [5.22-5.30], vs EtOH, 5.34 [5.30-5.38]; P = 0.06). EtOH ingestion resulted in similar plasma nonesterified fatty acid concentrations compared with rest (control, 0.43 [0.31-0.55] mmol·L, vs EtOH, 0.30 [0.21-0.40] mmol·L) and during exercise. Plasma lactate concentration was higher during the first 30 min of rest after EtOH consumption (mean concentration; control, 0.83 [0.77-0.90] mmol·L, vs EtOH, 1.00 [0.93-1.07] mmol·L), but the response during exercise was similar between conditions. CONCLUSIONS: Muscle glycogen utilization was similar during exercise with or without prior EtOH ingestion, reflected in similar total whole-body carbohydrate oxidation rates observed.

The Energy Cost of Sitting versus Standing Naturally in Man.

PURPOSE: Prolonged sitting is a major health concern, targeted via government policy and the proliferation of height-adjustable workstations and wearable technologies to encourage standing. Such interventions have the potential to influence energy balance and thus facilitate effective management of body/fat mass. It is therefore remarkable that the energy cost of sitting versus standing naturally remains unknown. METHODS: Metabolic requirements were quantified via indirect calorimetry from expired gases in 46 healthy men and women (age, 27 ± 12 yr; mass, 79.3 ± 14.7 kg; body mass index, 24.7 ± 3.1 kg·m, waist/hip, 0.81 ± 0.06) under basal conditions (i.e., resting metabolic rate) and then, in a randomized and counterbalanced sequence, during lying, sitting and standing. Critically, no restrictions were placed on natural/spontaneous bodily movements (i.e., fidgeting) to reveal the fundamental contrast between sitting and standing in situ while maintaining a comfortable posture. RESULTS: The mean (95% confidence interval [CI]) increment in energy expenditure was 0.18 (95% CI, 0.06-0.31 kJ·min) from resting metabolic rate to lying was 0.15 (95% CI, 0.03-0.27 kJ·min) from lying to sitting and 0.65 (95% CI, 0.53-0.77 kJ·min) from sitting to standing. An ancillary observation was that the energy cost of each posture above basal metabolic requirements exhibited marked interindividual variance, which was inversely correlated with resting heart rate for all postures (r = -0.5; -0.7 to -0.1) and positively correlated with self-reported physical activity levels for lying (r = 0.4; 0.1 to 0.7) and standing (r = 0.6; 0.3-0.8). CONCLUSIONS: Interventions designed to reduce sitting typically encourage 30 to 120 min·d more standing in situ (rather than perambulation), so the 12% difference from sitting to standing reported here does not represent an effective strategy for the treatment of obesity (i.e., weight loss) but could potentially attenuate any continued escalation of the ongoing obesity epidemic at a population level.