Use of respiratory quotients in assessment of aerobic work capacity

Issekutz, B; Birkhead, Newton C.; Rodahl, Kaare

doi:10.1152/jappl.1962.17.1.47

Cited by 148 publications

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“…Expired gas data was used to define V O 2max (greatest 30 s mean value) and the relevant sub-maximal running speeds for the experimental trials. All subjects were deemed to have attained V O 2max , as they achieved ≥2 of the following criteria: a plateau in V O 2 in the final exercise stage (Taylor et al 1955), RER ≥1.15 (Issekutz et al 1962), HR within 10 b min −1 of age-predicted maximum (220-age), RPE ≥19, blood [lactate] ≥8 mM (Midgley et al 2007). …”

Section: Maximal Exercise Testingmentioning

confidence: 99%

Dietary nitrate supplementation enhances short but not longer duration running time-trial performance

et al. 2017

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TT performance between conditions (2643.1 ± 324. 1 vs. 2649.9 ± 319.8 s, P > 0.05). Conclusion Acute BRJ supplementation significantly enhanced 1500 m, but not 10,000 m TT performance. These findings suggest that BRJ might be ergogenic during shorter distance TTs which allow for a high work rate, but not during longer distance TTs, completed at a lower work rate. ) supplementation on physiological functioning and exercise performance in trained runners/triathletes conducting short and longer-distance treadmill running time-trials (TT). Method Eight trained male runners or triathletes completed four exercise performance tests comprising a 10 min warm up followed by either a 1500 or 10,000 m treadmill TT. Exercise performance tests were preceded 3 h before the exercise by supplementation with either 140 ml concentrated nitrate-rich (~12.5 mmol nitrate) (BRJ) or nitratedeplete (~0.01 mmol nitrate) (PLA) beetroot juice. Results BRJ supplementation significantly elevated plasma [NO 2 − ] (P < 0.05). Resting blood pressure and exercise V O 2 were not significantly different between BRJ and PLA (P > 0.05). However, post-exercise blood [lactate] was significantly greater in BRJ following the 1500 m TT (6.6 ± 1.2 vs. 6.1 ± 1.5 mM; P < 0.05), but not significantly different between conditions in the 10,000 m TT (P > 0.05). Performance in the 1500 m TT was significantly faster in BRJ vs. PLA (319.6 ± 36.2 vs. 325.7 ± 38.8 s; P < 0.05). Conversely, there was no significant difference in 10,000 m Communicated by Keywords

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Section: Maximal Exercise Testingmentioning

confidence: 99%

Dietary nitrate supplementation enhances short but not longer duration running time-trial performance

et al. 2017

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“…Although the maximal respiratory exchange ratio varies significantly between individuals, a value Ͼ1.1 has been suggested as subsidiary evidence that a true V O 2 max has been attained. 35 The commonly used Weber classification of exercise capacity in heart failure patients is provided in Table 1. 36 A derivation of the Weber classification has also been applied to the level of VT and to the increase in CO with activity.…”

Section: Heart Failurementioning

confidence: 99%

Assessment of Functional Capacity in Clinical and Research Applications

Fleg¹,

Piña²,

Balady³

et al. 2000

Circulation

250

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A fundamental requirement for many of the activities of daily living is the ability to perform predominantly aerobic, ie, oxygen-using, work. Such activities require the integrated efforts of the heart, lungs, and circulation to deliver oxygen to the metabolically active muscle mass. Thus, the assessment of functional or aerobic exercise time or peak oxygen consumption provides important diagnostic and prognostic information in a wide variety of clinical settings. Furthermore, numerous clinical trials, especially those in patients with heart failure, have used aerobic exercise time or peak oxygen consumption as a primary or secondary end point. This brief advisory will highlight the major clinical and research applications of functional capacity assessment. For a comprehensive review of exercise testing, the reader is referred to the American College of Cardiology/American Heart Association Guidelines for Exercise Testing. 1 Physiology and TerminologyThe maximal capacity of an individual to perform aerobic work is defined by the maximal oxygen consumption (V O 2 max), the product of cardiac output (CO) and arteriovenous oxygen (AV O 2 ) difference at exhaustion. Although V O 2 max is measured in liters per minute, it is usually expressed per kilogram of body weight to facilitate intersubject comparisons. Functional capacity, particularly when estimated rather than measured directly, is often expressed in metabolic equivalents (METs); 1 MET represents resting energy expenditure and approximates 3.5 mL O 2 ⅐ kg Ϫ1 ⅐ min Ϫ1. Because V O 2 max is typically achieved by exercise that involves only about half of the total body musculature, it is generally believed that V O 2 max is limited by maximal CO rather than peripheral factors. 2 V O 2 max is affected by age, sex, conditioning status, and the presence of diseases or medications that influence its components. V O 2 max in a young world-class male endurance athlete can exceed 80 mL ⅐ kg Ϫ1 ⅐ min Ϫ1, whereas a value of 15 mL ⅐ kg Ϫ1 ⅐ min Ϫ1 is typical for a sedentary but healthy 80-year-old woman. Aerobic capacity declines 8% to 10% per decade in nonathletic subjects, 3 mediated largely by decreases in maximal heart rate and AV O 2 difference. Earlier studies suggested that the age-associated decline in V O 2 max may be attenuated to Ϸ5% per decade in endurance-trained subjects who continue to exercise vigorously. However, recent longitudinal observations with Ͼ20 years of follow-up have demonstrated declines of 10% to 15% per decade in such individuals, 4 mediated in part by a reduction in training intensity. At any age, V O 2 max in men is 10% to 20% greater than in women, in part because of a higher hemoglobin concentration, a larger proportion of muscle mass, and a greater stroke volume in men. These age and sex differences in V O 2 max must be considered in interpretations of functional capacity in individuals. Endurance training augments V O 2 max by 10% to 30% primarily by increasing maximal stroke volume and the AV O 2 difference. 5 True V O 2 max is usual...

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“…V O 2max was defined as the greatest 15-s mean value obtained. Our criteria for reaching V O 2max required a plateau in oxygen consumption (i. e., an increase in treadmill grade with no increase in oxygen consumption) and/or a respiratory exchange ratio (RER) over 1.15 [15]. All of our subjects reached V O 2max criteria.…”

Section: Methodsmentioning

confidence: 88%

“…We increased treadmill speed by 0.45 m · s − 1 (1 MPH) in each subsequent stage during both days. During the final minute of each 4-min stage, we asked subjects to provide a rating of perceived exertion (RPE) on the Borg (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) scale [9], until they reached an RPE of 15 (speed at RPE of 15 = sRPE15) on both days. Previous data have demonstrated that an RPE value of 16 represents an intensity that corresponds closely to LT [22].…”

Section: Methodsmentioning

confidence: 99%

Untitled

2017

Sports Med Int Open

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ABStR AC tRunning economy (oxygen uptake or metabolic rate for running at a submaximal speed) is one of the key determinants of distance running performance. Previous studies reported linear relationships between oxygen uptake or metabolic rate and speed, and an invariant cost of transport across speed. We quantified oxygen uptake, metabolic rate, and cost of transport in 10 average and 10 sub-elite runners. We increased treadmill speed by 0.45 m · s − 1 from 1.78 m · s − 1 (day 1) and 2.01 m · s − 1 (day 2) during each subsequent 4-min stage until reaching a speed that elicited a rating of perceived exertion of 15. Average runners' oxygen uptake and metabolic rate vs. speed relationships were best described by linear fits. In contrast, the subelite runners' relationships were best described by increasing curvilinear fits. For the sub-elites, oxygen cost of transport and energy cost of transport increased by 12.8 % and 9.6 %, respectively, from 3.58 to 5.14 m · s − 1 . Our results indicate that it is not possible to accurately predict metabolic rates at race pace for sub-elite competitive runners from data collected at moderate submaximal running speeds (2.68-3.58 m · s − 1 ). To do so, metabolic rate should be measured at speeds that approach competitive race pace and curvilinear fits should be used for extrapolation to race pace.

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Use of respiratory quotients in assessment of aerobic work capacity

Cited by 148 publications

References 0 publications

Dietary nitrate supplementation enhances short but not longer duration running time-trial performance

Dietary nitrate supplementation enhances short but not longer duration running time-trial performance

Assessment of Functional Capacity in Clinical and Research Applications

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