Cardiorespiratory responses during cycle ergometer exercise with different ramp slope increments in patients with chronic obstructive pulmonary disease

The Effect of High-Intensity Aerobic Exercise on the Pulmonary Function among Inactive Male Individuals

A spirometer is an important instrument in the assessment of the lung functions. FVC, FEV1, MVV and ratio of FEV1/FVC are indicators of strong respiratory function that deteriorate due to a sedentary lifestyle. Prolonged aerobic exercises are thought to improve aerobic capacity and to have a favorable effect on lung function. Thus, the main aim of this study was to investigate the effect of such aerobic exercise for three weeks, specifically continuous treadmill running, on lung function (FVC, FEV1, ratio of FEV1/FVC, and MVV) in inactive yet healthy male individuals. For this study, 72 inactive male individuals were given a pulmonary function test. The test was performed three times for each session (starting with five minutes and increasing by ten minutes every three sessions, up to a maximum of 25 minutes), and its mean value was used for analysis. Exercise was performed three days a week for three weeks. The Wilcoxon test was done to determine changes pre- to post-test. Repeated-measure analyses were used to compare the changes of pulmonary values between high-intensity sessions. Spearman correlation rho was conducted to assess association between MVV, FVC, and FEV1, and the Friedman test was used to compare the mean ratio of FEV1/FVC before and after exercise of different intensities. FEV1, MVV and a ratio of FEV1/FVC were significantly improved after high-intensity aerobic exercise of different intensities. In addition positive relation of MVV with FEV1 improvements was found. In contrast, there were insignificant improvements in FVC before and after exercise of different intensities and with no positive relation of MVV improvements. The improvements in MVV could reflect subtle changes in lung function or airway reactivity not detected by the FVC test. In addition, higher exercise intensity or longer duration may be needed to affect other lung function parameters like MVV, FEV1 and FEV1/FVC. Thus our results demonstrate that high-intensity aerobic exercise on the treadmill has a positive effect on the pulmonary function of inactive healthy subjects.

Reliability and Physiological Interpretation of Pulmonary Gas Exchange by "Circulatory Equivalents" in Chronic Heart Failure

BACKGROUND

Peak ratios of pulmonary gas-exchange to ventilation during exercise (V˙O2/V˙E and V˙CO2/V˙E, termed "circulatory equivalents") are sensitive to heart failure (HF) severity, likely reflecting low and/or poorly distributed pulmonary perfusion. We tested whether peak V˙O2/V˙E and V˙CO2/V˙E would: (1) distinguish HF patients from controls; (2) be independent of incremental exercise protocol; and (3) correlate with lactate threshold (LT) and ventilatory compensation point (VCP), respectively.

METHODS AND RESULTS

Twenty-four HF patients (61±11 years) with reduced ejection fraction (31±8%) and 11 controls (63±7 years) performed ramp-incremental cycle ergometry. Eighteen HF patients also performed slow (5±1 W/min), medium (9±4 W/min), and fast (19±6 W/min) ramps. Peak V˙O2/V˙E and V˙CO2/V˙E from X-Y plot, and LT and VCP from 9-panel plot, were determined by 2 independent, blinded, assessors. Peak V˙O2/V˙E (31.2±4.4 versus 41.8±4.8 mL/L; P<0.0001) and V˙CO2/V˙E (29.3±3.0 versus 36.9±4.0 mL/L; P<0.0001) were lower in HF than controls. Within individuals, there was no difference across 3 ramp rates in peak V˙O2/V˙E (P=0.62) or V˙CO2/V˙E (P=0.97). Coefficient of variation (CV) in peak V˙O2/V˙E was lower than for LT (5.1±2.1% versus 8.2±3.7%; P=0.014), and coefficient of variation in peak V˙CO2/V˙E was lower than for VCP (3.3±1.8% versus 8.7±4.2%; P<0.001). In all participants, peak V˙O2/V˙E was correlated with, but occurred earlier than, LT (r2=0.94; mean bias, -0.11 L/min), and peak V˙CO2/V˙E was correlated with, but occurred earlier than, VCP (r2=0.98; mean bias -0.08 L/min).

CONCLUSIONS

Peak circulatory equivalents during exercise are strongly associated with (but not identical to) LT and VCP. Peak circulatory equivalents are reliable, objective, effort-independent indices of gas-exchange abnormality in HF.

Influence of Pedaling Cadence and Incremental Protocol on the Estimation of EMGFT

Duff, TM, Fournier, H, Hopp, OB, Ochshorn, E, Sanders, ES, Stevens, RE, and Malek, MH. Influence of pedaling cadence and incremental protocol on the estimation of EMGFT. J Strength Cond Res 30(8): 2206-2211, 2016-Theoretically, the electromyographic fatigue threshold (EMGFT) is the highest exercise intensity that an individual can exercise at indefinitely without an increase in electromyography (EMG) amplitude. This index is estimated from a single incremental test. There are, however, factors that may influence EMG amplitude such as pedaling cadence or the incremental protocol used. The purposes of this study were to determine whether different pedaling cadences and/or incremental protocols influence the estimation of the EMGFT. Eight healthy college-aged men performed incremental cycle ergometry on three separate visits. The participants exercised using the following combinations of pedaling cadences and incremental protocols in random order: 25 W at 70 RPM; 13 W at 70 RPM; and 25 W at 100 RPM. The EMGFT value was determined from the vastus lateralis muscle of each participant for each of the three conditions. Separate 1-way repeated measures analysis of variances were performed to determine mean differences for various outcome indices. The mean maximal power output for the 13 W at 70 RPM condition was significantly lower than the two other conditions. There were, however, no significant mean differences (F (2,14) = 2.03; p = 0.169) for EMGFT between the three conditions. The findings of this study indicated that different pedaling cadences and incremental protocols did not influence the estimation of the EMGFT.

Comparison of laboratory- and field-based exercise tests for COPD: a systematic review

Exercise tests are often used to evaluate the functional status of patients with COPD. However, to the best of our knowledge, a comprehensive systematic comparison of these tests has not been performed. We systematically reviewed studies reporting the repeatability and/or reproducibility of these tests, and studies comparing their sensitivity to therapeutic intervention. A systematic review identified primary manuscripts in English reporting relevant data on the following exercise tests: 6-minute walk test (6MWT) and 12-minute walk test, incremental and endurance shuttle walk tests (ISWT and ESWT, respectively), incremental and endurance cycle ergometer tests, and incremental and endurance treadmill tests. We identified 71 relevant studies. Good repeatability (for the 6MWT and ESWT) and reproducibility (for the 6MWT, 12-minute walk test, ISWT, ESWT, and incremental cycle ergometer test) were reported by most studies assessing these tests, providing patients were familiarized with them beforehand. The 6MWT, ISWT, and particularly the ESWT were reported to be sensitive to therapeutic intervention. Protocol variations (eg, track layout or supplemental oxygen use) affected performance significantly in several studies. This review shows that while the validity of several tests has been established, for others further study is required. Future work will assess the link between these tests, physiological mechanisms, and patient-reported measures.

Neuromuscular and metabolic comparisons between ramp and step incremental cycle ergometer tests

INTRODUCTION

We compared peak and submaximal mean values for neuromuscular and metabolic parameters between ramp (15 W · min(-1)) and step (30 W increments every 2 min) incremental cycle ergometer tests.

METHODS

Thirteen healthy adults (7 men and 6 women; mean ± SD age = 23.4 ± 3.3 years) performed randomly ordered ramp or step incremental tests. Two-way repeated measures analyses of variance were used to analyze the data.

RESULTS

The ramp incremental test resulted in lower mean EMG amplitude, O2, and HR values at the common power outputs, with no differences for MMG amplitude values.

CONCLUSIONS

It is possible that the cumulative effect of producing an increased amount of work during the step (total work = 75.83 kJ) vs. ramp (total work = 65.60 kJ) incremental cycle ergometer tests at the common power outputs may have contributed to the greater fatigue-induced increase in muscle recruitment and/or firing rate, oxygen consumption, and heart rate.

Metabolic parameters for ramp versus step incremental cycle ergometer tests

The purpose of this study was to examine mean differences and the patterns of responses for oxygen uptake ([Formula: see text]O(2)), heart rate (HR), and rating of perceived exertion (RPE) for ramp (15 W·min(-1)) versus step (30 W increments every 2 min) incremental cycle ergometer tests. Fourteen subjects (age and body mass of 23.2 ± 3.1 (mean ± SD ) years and 71.1 ± 10.1 kg, respectively) visited the laboratory on separate occasions. Two-way repeated measures ANOVAs with appropriate follow-up procedures, as well as paired t tests, were used to analyze the data. In addition, polynomial regression analyses were used to determine the patterns of responses for each dependent variable for the ramp and step tests. The ramp protocol resulted in lower mean [Formula: see text]O(2) and HR values at the common power outputs than the step protocol with no differences in RPE. The increased amount of work performed during the step (total work = 75.83 kJ) versus ramp (total work = 65.60 kJ) tests at the common power outputs may have contributed to the greater [Formula: see text]O(2) and HR values. The polynomial regression analyses showed that most subjects had the same patterns of responses for the ramp and step incremental tests for HR (86%) and RPE (93%) but different patterns for [Formula: see text]O(2) (71%). The findings from the present study suggested that the protocol selection for an incremental cycle ergometer test can affect the mean values for [Formula: see text]O(2) and HR, as well as the [Formula: see text]O(2) - power output relationship.

Test-Retest Reliability and Physiological Responses Associated with the Steep Ramp Anaerobic Test in Patients with COPD

The Steep Ramp Anaerobic Test (SRAT) was developed as a clinical test of anaerobic leg muscle function for use in determining anaerobic power and in prescribing high-intensity interval exercise in patients with chronic heart failure and Chronic Obstructive Pulmonary Disease (COPD); however, neither the test-retest reliability nor the physiological qualities of this test have been reported. We therefore, assessed test-retest reliability of the SRAT and the physiological characteristics associated with the test in patients with COPD. 11 COPD patients (mean FEV₁ 43% predicted) performed a cardiopulmonary exercise test (CPET) on Day 1, and an SRAT and a 30-second Wingate anaerobic test (WAT) on each of Days 2 and 3. The SRAT showed a high degree of test-retest reliability (ICC = 0.99; CV = 3.8%, and bias 4.5 W, error −15.3–24.4 W). Power output on the SRAT was 157 W compared to 66 W on the CPET and 231 W on the WAT. Despite the differences in workload, patients exhibited similar metabolic and ventilatory responses between the three tests. Measures of ventilatory constraint correlated more strongly with the CPET than the WAT; however, physiological variables correlated more strongly with the WAT. The SRAT is a highly reliable test that better reflects physiological performance on a WAT power test despite a similar level of ventilatory constraint compared to CPET.

Why peak power is higher at the end of steeper ramps: an explanation based on the "critical power" concept

Experimental studies have consistently reported higher peak power outputs at the termination of steeper ramp exercises. One explanation can be deduced from oxygen uptake kinetics. This short communication offers an alternative explanation based on the "critical power" concept of human bioenergetics. Algebraic, calculus, and geometric aspects of this explanation are all detailed, and it is illustrated with data from a previous study.

Using the oxygen-cost diagram in ramp-slope selection for dyspneic patients

BACKGROUND

Maximal incremental exercise testing should be completed within 8-12 minutes. The ramp-slope influences the exercise duration. Oxygen-cost diagram (OCD) is a scoring scale for the capability of daily activity performed and therefore can be used to estimate the ramp-slope.

METHODS

The OCD-algorithm and the reported-algorithm were used prospectively in random order for selecting optimal ramp-slope: Ramp-slope(OCD)=Score(OCD)xweight in kg/40 for men and weight/50 for women and Ramp-slope(reported)=(Predicted V(O2peak)-V(O2unloaded))/100. Fifty-three dyspneic patients and 16 normal controls were enrolled to perform a ramp-pattern exercise. Fourteen patients not reaching maximum exercise levels were excluded. The exercise capacity, exercise time, and success rate of loaded exercise between 8 and 12 minutes were measured.

RESULTS

Comparing the reported-algorithm to the OCD-algorithm in normal controls, the only difference was that the ramp-slope was higher in males; in patients, the ramp-slope was higher in males, the exercise time shorter and the success rate lower (8.6+/-3.3 vs. 9.4+/-2.1 min, 61.5% vs. 84.6%, both p<0.05); in obese patients, the ramp-slope was lower and the exercise time longer.

CONCLUSION

OCD score can predict the ramp-slope selection for exercise testing in normal controls and dyspneic patients. This may be affected by gender and body weight when using the reported-algorithm for dyspneic patients.

Using baseline respiratory function data to optimize cycle exercise test duration

BACKGROUND

It is often difficult to select an appropriate workload increment for progressive cycle exercise tests in order to achieve optimal test duration (8-12 min). We hypothesize that baseline respiratory function can be systematically used to select appropriate workload increment to optimize test duration in patients referred to the clinical laboratory.

METHODOLOGY

One hundred and eighty consecutive exercise tests (with increments of 15 W/min) were retrospectively assessed. Using regression analysis, an equation was generated that predicts the work rate increment that would provide exercise duration of 8-12 min. The validity of this equation was tested prospectively in 231 consecutive tests performed with the calculated workload increment rounded to the nearest 5 watts (W).

RESULTS

The best regression equation was: workload increment (W/min)=1.94 x FEV1 (L) + 0.63 x TLCO (mmol/min per kPa) - 0.07 x age + 1.94 x gender (male=1, female=0) + 4.12 (r=0.85, P < 0.0001). Using this equation allowed selection of the most appropriate workload increment in 79% of tests and reduced the number of tests of non-optimal duration from 72% (for a fixed increment of 15 W/min) to 38%.

CONCLUSIONS

Utilization of this regression equation allows standardization in the selection of workload increment, and reduces the number of cycle exercise tests of inadequate duration.