Topic
Work rate
About: Work rate is a research topic. Over the lifetime, 40 publications have been published within this topic receiving 3750 citations.
Papers published on a yearly basis
Papers
TL;DR: It is concluded that most COPD subjects studied increased blood lactate at low work rates, and this findings provide a physiologic rationale for exercise training of patients with COPD.
Abstract: Though exercise training is part of most pulmonary rehabilitation programs, whether there is a physiologic basis for increased exercise tolerance is unclear. We sought to determine whether patients with chronic obstructive pulmonary disease (COPD) are capable of obtaining a physiologic training effect, as manifested by a reduction in blood lactate and ventilation (VE) at a given level of exercise. We also sought to determine whether training work rate determines the size of the training effect. Nineteen participants with COPD of predominantly moderate severity in an inpatient rehabilitation program performed two cycle ergometer exercise tests at a low and a high work rate for 15 min or to tolerance and also an incremental exercise test to tolerance. Arterial blood was sampled for blood gas and lactate analyses. Identical tests were performed before and after 5-day-per-week cycle ergometer training for 8 wk either for 45 min/day at a high work rate (average, 71 W) or for a proportionally longer time at a low work rate (average, 30 W). Average FEV1 was 56 +/- 12% predicted and did not change with training. Peak exercise lactate (average, 6.5 mEq/L) was not correlated with FEV1. For the high work rate training group, identical work rates engendered less lactate (4.5 versus 7.2 mEq/L) and less VE (48 versus 55 L/min) after training; the low work rate training group had significantly less lactate and VE decrease (p less than 0.01). Further, endurance time for the high constant work rate increased 73% in the high work rate training group but only 9% in the low work rate training group. At identical work rates, VE decrease average 2.5 L/min per mEq/L decrease in lactate (r = 0.75). We conclude that most COPD subjects studied increased blood lactate at low work rates. Many of these patients were able to achieve a physiologic training effect. Though total work was the same, training at a high work rate was more effective than was training at a low work rate. The lower VE requirement to perform exercise was in proportion to the lower lactate level, but the VE decrease for a given decrease in lactate was smaller than that seen in normal subjects (7.2 L/min/mEq/L), apparently because patients with COPD fall to hyperventilate in response to lactic acidosis (PaCO2 does not drop). These findings provide a physiologic rationale for exercise training of patients with COPD.
874 citations
1 Jan 1976
611 citations
TL;DR: The justification for relating lactate increase to tissue anaerobiosis during exercise is presented, and the gas exchange methods for measuring the anaerobic threshold are described.
Abstract: During exercise, the oxygen consumption above which aerobic energy production is supplemented by anaerobic mechanisms, and which results in a significant increase in lactate, is termed the anaerobic threshold (AT). This power output has important functional implications because it is a demarcation of the work rate above which metabolic acidosis accelerates the stimulation to breathing, and exercise endurance becomes reduced. The justification for relating lactate increase to tissue anaerobiosis during exercise is presented, and the gas exchange methods for measuring the AT are described. The form of work affects the AT, treadmill being about 10% greater than cycling in sedentary subjects. It is useful for predicting the ability of the subject to sustain a given work rate for a prolonged period and for determining the VO2 above which there is cardiovascular insufficiency in meeting tissue O2 requirements.
457 citations
TL;DR: Modification of the stage duration during an incremental exercise test may influence the submaximal and maximal physiological variables and change the validity of using these results for predicting performance, and prescribing or monitoring training.
Abstract: Physiological variables, such as maximum work rate or maximal oxygen uptake (VO2max), together with other submaximal metabolic inflection points (e.g. the lactate threshold [LT], the onset of blood lactate accumulation and the pulmonary ventilation threshold [VT]), are regularly quantified by sports scientists during an incremental exercise test to exhaustion. These variables have been shown to correlate with endurance performance, have been used to prescribe exercise training loads and are useful to monitor adaptation to training. However, an incremental exercise test can be modified in terms of starting and subsequent work rates, increments and duration of each stage. At the same time, the analysis of the blood lactate/ventilatory response to incremental exercise may vary due to the medium of blood analysed and the treatment (or mathematical modelling) of data following the test to model the metabolic inflection points. Modification of the stage duration during an incremental exercise test may influence the submaximal and maximal physiological variables. In particular, the peak power output is reduced in incremental exercise tests that have stages of longer duration. Furthermore, the VT or LT may also occur at higher absolute exercise work rate in incremental tests comprising shorter stages. These effects may influence the relationship of the variables to endurance performance or potentially influence the sensitivity of these results to endurance training. A difference in maximum work rate with modification of incremental exercise test design may change the validity of using these results for predicting performance, and prescribing or monitoring training. Sports scientists and coaches should consider these factors when conducting incremental exercise testing for the purposes of performance diagnostics.
382 citations
TL;DR: The results show that the adaptations to endurance exercise training enable an individual to adjust to the energy requirement of constant load submaximal work more rapidly, resulting in a smaller O2 deficit.
Abstract: This study was undertaken to evaluate the effects of endurance exercise training on O2 deficit and O2 debt, and on the time courses of the adjustment to, and recovery from, submaximal exercise of oxygen uptake (VO2) carbon dioxide production (VCO2), minute ventilation (VE), and heart rate (HR). Eight subjects participated in a 9-wk-long exercise program that increased their VO2max by 24%. It was found that O2 deficit and O2 debt were lower at the same absolute work rate and not significantly different at the same relative work rate after training. The increases in VO2, VCO2, VE, and HR at the onset of constant load submaximal work, and the decreases in VO2, VCO2, VE, and HR in recovery were more rapid at both the same absolute and the same relative work rates after training. These results show that the adaptations to endurance exercise training enable an individual to adjust to the energy requirement of constant load submaximal work more rapidly, resulting in a smaller O2 deficit. The rate of recovery is also more rapid after training, resulting in a smaller O2 debt.
358 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 2 |
| 2024 | 4 |
| 2023 | 5 |
| 2022 | 11 |
| 2021 | 2 |
| 2020 | 2 |