The purpose of this study was to assess the validity and reliability of the MedGem™ device to measure resting metabolic rate (RMR) in children. Subjects included 59 children (29 boys, 30 girls; mean age, 11.0 ± 0.2 y). Subjects were given 4 RMR tests during 1 test session, cconsisting of 2 Douglas bag and 2 MedGem tests, in random counterbalanced order. No significant differences were found between Douglas bag and MedGem systems for oxygen consumption (209 ± 5 and 213 ± 5 mL/min, respectively, P = 0.106, r = 0.911, mean ± standard deviation absolute difference 3.72 ± 17.40 mL/min) or RMR (1460 ± 39 and 1477 ± 35 kcal/d, P = 0.286, r = 0.909, mean ± standard deviation absolute difference 17.4 ± 124 kcal/d). Standard error of estimates for oxygen consumption and RMR were 17.4 mL/min and 124 kcal/d, respectively. In conclusion, these data indicate that the MedGem is a reliable and valid system for measuring oxygen consumption and RMR in children.
David C. Nieman, Melanie D. Austin, Shannon M. Chilcote, and Laura Benezra
Antonio Paoli, Giuseppe Marcolin, Fabio Zonin, Marco Neri, Andrea Sivieri, and Quirico F. Pacelli
Exercise and nutrition are often used in combination to lose body fat and reduce weight. In this respect, exercise programs are as important as correct nutrition. Several issues are still controversial in this field, and among them there are contrasting reports on whether training in a fasting condition can enhance weight loss by stimulating lipolytic activity. The authors’ purpose was to verify differences in fat metabolism during training in fasting or feeding conditions. They compared the effect on oxygen consumption (VO2) and substrate utilization, estimated by the respiratory-exchange ratio (RER), in 8 healthy young men who performed the same moderate-intensity training session (36 min of cardiovascular training on treadmill at 65% maximum heart rate) in the morning in 2 tests in random sequence: FST test (fasting condition) without any food intake or FED test (feeding condition) after breakfast. In both cases, the same total amount and quality of food was assumed in the 24 hr after the training session. The breakfast, per se, increased both VO2 and RER significantly (4.21 vs. 3.74 and 0.96 vs. 0.84, respectively). Twelve hours after the training session, VO2 was still higher in the FED test, whereas RER was significantly lower in the FED test, indicating greater lipid utilization. The difference was still significant 24 hr after exercise. The authors conclude that when moderate endurance exercise is done to lose body fat, fasting before exercise does not enhance lipid utilization; rather, physical activity after a light meal is advisable.
Sebastian Sitko, Rafel Cirer-Sastre, Francisco Corbi, and Isaac López-Laval
In recent years, multiple performance factors have been identified in road cycling. 1 Among the physiological determinants of performance, maximal oxygen consumption (VO 2 max) adjusted to body mass can be highlighted as a key parameter of cardiorespiratory fitness. 2 Normally, gas exchange
James R. Mckee, Bradley A. Wall, and Jeremiah J. Peiffer
. However, for aerobic adaptation (ie, increases in cardiac output and maximal oxygen consumption [ V ˙ O 2 max ]), the total time an individual spends at or near their V ˙ O 2 max is an important consideration. 5 , 6 Many studies have examined the influence of interval structure on the time spent at or
Kevin E. Miller, Timothy R. Kempf, Brian C. Rider, and Scott A. Conger
Maximal oxygen consumption ( V ˙ O 2 max ) plays an integral role in health and wellness. The assessment of V ˙ O 2 max can be used to prescribe exercise intensity, evaluate the progress of an exercise program, and evaluate endurance performance potential ( American College of Sports Medicine
Christopher R.J. Fennell and James G. Hopker
reflects the ratio of oxygen (O 2 ) delivery to the working muscle and muscle oxygen uptake in the capillary beds. 17 The recovery of muscle oxygen consumption ( m V ˙ O 2 ) considers the condition of the exercising muscle, as measurements are derived directly from the muscle body. It has been suggested
Roland van den Tillaar, Erna von Heimburg, and Guro Strøm Solli
Maximal oxygen consumption (VO 2 max) is defined as the highest rate at which oxygen can be taken up and utilized by the body during intensive exercise. 1 The VO 2 max test is frequently used as a measure of the cardiorespiratory fitness level of an individual or as a physiological marker for
Darlene A. Sedlock, Man-Gyoon Lee, Michael G. Flynn, Kyung-Shin Park, and Gary H. Kamimori
Literature examining the effects of aerobic exercise training on excess postexercise oxygen consumption (EPOC) is sparse. In this study, 9 male participants (19–32 yr) trained (EX) for 12 wk, and 10 in a control group (CON) maintained normal activity. VO2max, rectal temperature (Tre), epinephrine, norepinephrine, free fatty acids (FFA), insulin, glucose, blood lactate (BLA), and EPOC were measured before (PRE) and after (POST) the intervention. EPOC at PRE was measured for 120 min after 30 min of treadmill running at 70% VO2max. EX completed 2 EPOC trials at POST, i.e., at the same absolute (ABS) and relative (REL) intensity; 1 EPOC test for CON served as both the ABS and REL trial because no significant change in VO2max was noted. During the ABS trial, total EPOC decreased significantly (p < .01) from PRE (39.4 ± 3.6 kcal) to POST (31.7 ± 2.2 kcal). Tre, epinephrine, insulin, glucose, and BLA at end-exercise or during recovery were significantly lower and FFA significantly higher after training. Training did not significantly affect EPOC during the REL trial; however, epinephrine was significantly lower, and norepinephrine and FFA, significantly higher, at endexercise after training. Results indicate that EPOC varies as a function of relative rather than absolute metabolic stress and that training improves the efficiency of metabolic regulation during recovery from exercise. Mechanisms for the decreased magnitude of EPOC in the ABS trial include decreases in BLA, Tre, and perhaps epinephrine-mediated hepatic glucose production and insulin-mediated glucose uptake.
Eadric Bressel and Gary D. Heise
The purpose of this study was to compare muscle activity, kinematic, and oxygen consumption characteristics between forward and reverse arm cranking. Twenty able-bodied men performed 5-min exercise bouts of forward and reverse arm cranking while electromyographic (EMG), kinematic, and oxygen consumption data were collected. EMG activity of biceps brachii, triceps brachii, deltoid, and infraspinatus muscles were recorded and analyzed to reflect on-time durations and amplitudes for each half-cycle (first 180° and second 180° of crank cycle). Kinematic data were quantified from digitization of video images, and oxygen consumption was calculated from expired gases. Dependent measures were analyzed with a MANOVA and follow-up univariate procedures; alpha was set at .01. The biceps brachii, deltoid, and infraspinatus muscles displayed greater on-time durations and amplitudes for select half-cycles of reverse arm cranking compared to forward arm cranking (p < 0.01). Peak wrist flexion was 9% less in reverse arm cranking (p < 0.01), and oxygen consumption values did not differ between conditions (p = 0.25). Although there were no differences in oxygen consumption and only minor differences kinematically, reverse arm cranking requires greater muscle activity from the biceps brachii, deltoid, and infraspinatus muscles. These results may allow clinicians to more effectively choose an arm cranking direction that either minimizes or maximizes upper extremity muscle activity depending on the treatment objectives.
Kristin L. Osterberg and Christopher L. Melby
This study determined the effect of an intense bout of resistive exercise on postexercise oxygen consumption, resting metabolic rate, and resting fat oxidation in young women (N = 7, ages 22-35). On the morning of Day 1, resting metabolic rate (RMR) was measured by indirect calorimetry. At 13:00 hr, preexercise resting oxygen consumption was measured followed by 100 min of resistive exercise. Postexercise oxygen consumption was then measured for a 3-hr recovery period. On the following morning (Day 2), RMR was once again measured in a fasted state at 07:00. Postexercise oxygen consumption remained elevated during the entire 3-hr postexercise recovery period compared to the pre-exercise baseline. Resting metabolic rate was increased by 4.2% (p < .05) from Day 1 (morning prior to exercise: 1,419 ± 58 kcal/24 hr) compared to Day 2 (16 hr following exercise: 1,479 ± 65 kcal/24 hr). Resting fat oxidation as determined by the respiratory exchange ratio was also significantly elevated on Day 2 compared to Day 1. These results indicate that among young women, acute strenuous resistance exercise of the nature used in this study is capable of producing modest but prolonged elevations of postexercise metabolic rate and possibly fat oxidation.