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Christopher Reiff, Kara Marlatt, and Donald R. Dengel

Background:

Traditional desks require students to sit; however, recently schools have provided students with nontraditional standing desks. The purpose of this study was to investigate differences in caloric expenditure of young adults while sitting at a standard classroom desk and standing at a nontraditional standing classroom desk.

Methods:

Twenty (10 male/10 female) young (22.8 ± 1.9 y), healthy participants reported to the laboratory between the hours of 7:00 AM and 2:00 PM following a 12-h fast and 48-h break in exercise. Participants were randomly assigned to perform a series of mathematical problems either sitting at a normal classroom desk or standing at a nontraditional standing desk. Inspired and expired gases were collected for 45-min for the determination of oxygen consumption (VO2), carbon dioxide production (VCO2), and minute ventilation (VE) using a metabolic gas system.

Results:

There were significant increases from sitting to standing in VO2 (0.22 ± 0.05 vs. 0.28 ± 0.05 L·min−1, P ≤ .0001), VCO2 (0.18 ± 0.05 vs. 0.24 ± 0.050 L·min−1, P ≤ .0001), VE (7.72 ± 0.67 vs. 9.41 ± 1.20 L·min−1, P ≤ .0001), and kilocalories expended per minute (1.36 ± 0.20 kcal/ min, P ≤ .0001 vs. 1.02 ± 0.22 kcal/min, P ≤ .0001).

Conclusions:

Results indicate a significant increase in caloric expenditure in subjects that were standing at a standing classroom desk compared with sitting at a standard classroom desk.

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Filippo Dolci, Andrew E. Kilding, Tania Spiteri, Paola Chivers, Ben Piggott, Andrew Maiorana, and Nicolas H. Hart

standardized conditions. Gas Analysis Oxygen consumption (VO 2 ), carbon dioxide production, and the respiratory exchange ratio for each running mode (RE, SRE 20 , and SRE 10 ) were recorded throughout testing. The data were filtered to eliminate signal artifact and averaged over multiple 15-second periods

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Reginald L. Washington

The ventilatory anaerobic threshold (VAT) occurs when there is an isolated increase in the slope for ventilator equivalent for oxygen consumption (VE/VO2) with no change in the slope for ventilatoiy equivalent for carbon dioxide production (VE/VCO2) when both are plotted against time. The concept of anaerobic threshold remains controversial. However, it is a clinically useful tool in evaluating the exercise capacity of children. This paper will review the history, biochemistry, and methodology involved in determining the anaerobic threshold, as well as the ventilatory anaerobic threshold in children.

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James L. Seale, Robert S. VanZant, and Joan M. Conway

Fifteen adult male volunteers were assigned to sedentary, moderately strength-trained, and moderately endurance-trained groups (5 per group) to determine the effect of exercise training on energy expenditure (EE). Subjects were matched for age, weight, and height. Group appointments were based on activity questionnaires and American College of Sports Medicine standards. Subjects consumed a mixed diet of 40% fat, 20% protein, and 40% carbohydrate at weight maintenance intake for 3 weeks while continuing their exercise training programs. There was no significant difference between groups for 24-hr EE measured in the controlled environment of a room-sized calorimeter. Free-living EE measured with H2218O in endurance- and strength-trained groups was significantly higher (19.4% and 35.1%, respectively) than in the sedentary group. Moderate endurance and strength training increased free-living EE but did not affect 24-hr EE when groups followed standardized activity schedules. These results suggest that increased EE caused by moderate exercise training is limited to the energy required to complete the exercise.

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Karin M. Volkers, Tim C.W. van Dijk, Laura H. Eggermont, A. Peter Hollander, and Erik J.A. Scherder

Introduction:

The American College of Sports Medicine prescribes regular performance of at least moderate-intensity physical activity for healthy aging. This study examined whether 1 session of 30 min of chair-assisted exercises for the elderly meets this intensity criterion.

Method:

This cross-sectional study included 47 cognitively healthy volunteers (mean age 84 years). During the performance of 30 min of chair-assisted exercises the authors determined oxygen uptake (VO2), carbon dioxide production, heart rate (HR), and rating of perceived exertion (RPE). These measures were expressed as a percentage of the estimated maximal VO2 (VO2max) and the estimated maximal HR (HRmax) and estimated as metabolic equivalent units (METs).

Results:

Participants performed chair-assisted exercises at 61.0% ± 14.7% of VO2max, 67.6% ± 11.3% HRmax, 3.9 ± 0.9 METs, and 13.1 ± 2.1 RPE.

Conclusions:

The intensity of these chair-assisted exercises is at least moderate for older adults, which is necessary for healthy aging.

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Herman-J. Engels and Emily M. Haymes

This study examined the effects of a single dose of caffeine (5 mg:kg−1) on energy metabolism during 60-min treadmill walking at light (30% VO2max) and moderate (50% VO2max) aerobic intensities in eight sedentary (VO2max 39.6 ±t3.1 ml.kg−1.min−1) males. Caffeine intake 60 min prior to walking exercise increased pre- and postexercise FFA, glycerol, and lactate concentrations (p < 0.05). Blood glucose levels following walking trials were lower than preexercise values (p < 0.05). Gas exchange indicated that caffeine did not change exercise oxygen uptake, RER values, and carbon dioxide production (p0.05). In contrast, a small but statistically significant effect of caffeine on exercise minute ventilation was noted (p~0.01). It is concluded that ingestion of 5 mg.kg−1 caffeine increases the mobilization of energy substrate from fat sources; however, the present data do not provide evidence of a caffeineinduced shift in energy substrate usage. Caffeine is not an effective means for enhancing the energy cost of prolonged walking.

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Mark Loftin, Melinda Sothern, Georgianna Tuuri, Connie Tompkins, Cathie Koss, and Marc Bonis

Purpose:

The aim of this investigation was to compare gender differences in physiologic and perceptual responses during a 1-h run at recent marathon pace and running economy at three speeds in recreational marathon runners.

Methods:

In a counterbalanced design, 10 men and 10 women completed a 1-h treadmill run and a running economy test. Treadmill speed for the 1-h run ranged from 141 to 241 m·min−1 and 134, 168, and 188 m·min−1 for running economy. Physiologic parameters (oxygen uptake, carbon dioxide production, pulmonary ventilation, and heart rate) and perceived exertion were measured. Repeated-measures ANOVA was used to compare any gender differences (P < .05) during the 1-h run and a two-way ANOVA was used to compare running economy. With this sample, estimated marathon energy expenditure, body composition, and maximal physiologic function was reported.1

Results:

With the exception of an allometric expression of VO2 (mL·min−1·kg BW−0.75), similar gender physiologic and perceptual responses were found during the 1-h run. Although not significant, the females exercised at a higher percent VO2max (8% to 9%) during the run. Similar gender differences were also noted during the running economy tests.

Conclusions:

Although the male runners completed a recent marathon significantly faster than the females, similar gender physiologic and perceptual responses were generally found during the 1-h treadmill run and the running economy tests.

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David M. Shaw, Fabrice Merien, Andrea Braakhuis, Daniel Plews, Paul Laursen, and Deborah K. Dulson

This study investigated the effect of the racemic β-hydroxybutyrate (βHB) precursor, R,S-1,3-butanediol (BD), on time-trial (TT) performance and tolerability. A repeated-measures, randomized, crossover study was conducted in nine trained male cyclists (age, 26.7 ± 5.2 years; body mass, 69.6 ± 8.4 kg; height, 1.82 ± 0.09 m; body mass index, 21.2 ± 1.5 kg/m2; VO2peak,63.9 ± 2.5 ml·kg−1·min−1; Wmax, 389.3 ± 50.4 W). Participants ingested 0.35 g/kg of BD or placebo 30 min before and 60 min during 85 min of steady-state exercise, which preceded a ∼25- to 35-min TT (i.e., 7 kJ/kg). The ingestion of BD increased blood D-βHB concentration throughout exercise (0.44–0.79 mmol/L) compared with placebo (0.11–0.16 mmol/L; all p < .001), which peaked 1 hr following the TT (1.38 ± 0.35 vs. 0.34 ± 0.24 mmol/L; p < .001). Serum glucose and blood lactate concentrations were not different between trials (all p > .05). BD ingestion increased oxygen consumption and carbon dioxide production after 20 min of steady-state exercise (p = .002 and p = .032, respectively); however, no further effects on cardiorespiratory parameters were observed. Within the BD trial, moderate to severe gastrointestinal symptoms were reported in five participants, and low levels of dizziness, nausea, and euphoria were reported in two participants. However, this had no effect on TT duration (placebo, 28.5 ± 3.6 min; BD, 28.7 ± 3.2 min; p = .62) and average power output (placebo, 290.1 ± 53.7 W; BD, 286.4 ± 45.9 W; p = .50). These results suggest that BD has no benefit for endurance performance.

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Andrew T. Scott, Thomas O’Leary, Simon Walker, and Rachel Owen

Purpose:

To investigate the effect of ingesting a caffeinated carbohydrate gel (CC) 10 minutes prior on 2000-m rowing performance compared with a carbohydrate-only placebo gel (CP).

Methods:

A counterbalanced, single-blind, crossover study design was employed (N = 13). All participants completed 1 familiarization trial followed by 2 experimental rowing time trials. The experimental trials were performed 10 min after ingesting CP (21.6 g of carbohydrate, 0 mg caffeine) or CC (21.6 g carbohydrate, 100 mg caffeine), and heart rate (HR), oxygen consumption (VO2), carbon dioxide production, minute ventilation (VE), respiratory-exchange ratio (RER), rating of perceived exertion (RPE), gastrointestinal discomfort (GI), and thirst perception (Thirst) were recorded every 200 m. Blood lactate [La] was recorded immediately before and after exercise.

Results:

A paired-samples t test identified a significant improvement in 2000-m performance of 5.2 ± 3.9 s (1.1% ± 1.7%; P = .034). Two-way repeated-measures ANOVA revealed no significant treatment effect for HR (177 ± 8 vs 177 ± 9 beats/min, P = .817), VO2 (46.1 ± 6.5 vs 46.6 ± 6.2 mL · kg−1 · min−1, P = .590), VE (121.8 ± 14.7 vs 124.8 ± 15.7 L/min, P = .490), RPE, GI, or Thirst for CP and CC, respectively. Paired-samples t tests revealed no treatment effect for postexercise [La] between CP and CC (11.72 ± 2.69 vs 12.26 ± 3.13 mmol/L, P = .534).

Conclusion:

A relatively low dose of caffeine (1.3 ± 0.1 mg/kg body mass) in an isotonic carbohydrate gel ingested only 10 min before performance improved 2000-m rowing time by 5.2 ± 7.8 s (1.1% ± 1.7%).

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Giovanna Ghiani, Sara Magnani, Azzurra Doneddu, Gianmarco Sainas, Virginia Pinna, Marco Caboi, Girolamo Palazzolo, Filippo Tocco, and Antonio Crisafulli

Solo race. In detail, carbon dioxide production (VCO 2 ), respiratory exchange ratio, pulmonary ventilation, and workload at AT increased during arm cranking after the race. Moreover, there were evident increments in VO 2 , VCO 2 , respiratory exchange ratio, pulmonary ventilation, and oxygen pulse at