Aerobic Exercise Prescription in Cardiac Rehabilitation Based on Heart Rate from Talk Test Stages and 6-Minute Walk Test

BACKGROUND

Although the Talk Test (TT) is a reliable and low-cost test, its use for aerobic exercise prescription is still limited.

OBJECTIVE

To analyze the heart rate (HR) in the stages of the TT and at the peak of the 6-minute walk test (6MWT) as a parameter to prescribe aerobic exercise compared with HR at the first and second ventilatory thresholds (VT1 and VT2) of cardiopulmonary exercise test (CPET).

METHODS

Individuals with cardiovascular disease attended three assessment days: 1) anamnesis and CPET; 2) 6MWT; and 3) TT. One-way repeated measures ANOVA or Friedman's test were used to compare HR at VT1 and VT2 with HR at TT stages: last positive (TT+), first equivocal (TT±), and negative (TT-), and at the peak of the 6MWT. Pearson's or Spearman's test assessed correlations between HR at VTs, TT stages, and 6MWT. Statistical significance was set at 5%.

RESULTS

The study included 22 cardiac patients (13 men, 61 ± 8 years). HR at VT1 was similar to HR at TT+ (p = 0.987) and TT± (p = 0.154), and moderately correlated with TT+ (r = 0.479, p = 0.024). HR at VT2 was similar to TT- (p = 0.383), with a strong correlation (r = 0.757, p < 0.001). HR at the peak of the 6MWT was significantly different from HR at TT+, TT±, and VT1 (p = 0.001, p = 0.005, and p < 0.001, respectively) but similar to TT- (p = 0.68).

CONCLUSIONS

HR at TT+ and TT- reflect HR at VT1 and VT2, respectively, differently from 6MWT, which was similar only to VT2. TT may be an objective test to assist aerobic exercise prescription in cardiac rehabilitation.

Effects of high-intensity and moderate-intensity exercise training on cardiopulmonary function in patients with coronary artery disease: A meta-analysis

Purpose

The study aims to evaluate the effects of high-intensity and moderate-intensity exercise training on cardiopulmonary function and exercise endurance in patients with coronary artery diseases (CAD).

Methods

We performed a systematic search of the English and Chinese databases from their inception to March 2022. Randomized controlled trials (RCTs) were included to compare high-intensity and moderate-intensity exercise training on cardiopulmonary function in patients with CAD. The primary outcomes included peak oxygen uptake (peak VO₂) and anaerobic threshold (AT). The secondary outcomes included left ventricular ejection fraction (LVEF), exercises duration (ED), respiratory exchange ratio (RER), resting heart rate (RHR), peak heart rate (PHR) and oxygen pulse (O₂ pulse). The continuous variables were expressed as mean differences (MD) along with their corresponding standard deviations (SD), and the I² test was applied in the assessment of heterogeneity.

Results

After systematically literature search, 19 studies were finally selected for our meta-analysis (n = 1,036), with 511 patients in the experimental group (high-intensity exercise) and 525 patients in the control group (moderate-intensity exercise). The results showed that high-intensity exercise significantly increased patients' Peak VO₂ [MD = 2.67, 95% CI (2.24, 3.09), P < 0.00001], LVEF [MD = 3.60, 95% CI (2.17, 5.03), P < 0.00001], ED [MD = 37.51, 95% CI (34.02, 41.00), P < 0.00001], PHR [MD = 6.86, 95% CI (4.49, 9.24), P < 0.00001], and O₂ pulse [MD = 0.97, 95% CI (0.34, 1.60), P = 0.003] compared with moderate-intensity exercise. However, there were no significant differences in AT [MD = 0.49, 95% CI (−0.12, 1.10), P = 0.11], RER [MD = 0.00, 95% CI (−0.01, 0.02), P = 0.56], and RHR [MD = 1.10, 95% CI (−0.43, 2.63), P = 0.16].

Conclusion

Our results show that high-intensity exercise training has more significant positive effects compared with moderate-intensity exercise training in improving peak VO₂, LVEF, ED, PHR and O₂ pulse in patients with CAD, while no significant differences were observed in AT, RER and RHR. To sum up, high-intensity exercise training is better than moderate-intensity exercise training in improving cardiopulmonary function and exercise endurance in patients with CAD.

Systematic review registration

PROSPERO (CRD42022328475), https://www.crd.york.ac.uk/PROSPERO/.

Which high-intensity interval training program is more effective in patients with coronary artery disease?

The aim of the study is to examine high-intensity interval training (HIIT) programs and a moderate-intensity continuous training (MICT) program, which are frequently used in cardiac rehabilitation programs in terms of their effects on the functional capacity and quality of life of patients with coronary artery disease (CAD). The study included 20 patients with CAD (mean age, 60.95 ± 5.08 years) who had undergone revascularization surgery. The participants were randomized into HIIT-short, HIIT-long, and MICT groups. All the groups participated in a 24-session exercise-based cardiac rehabilitation program. The participants' exercise capacity was evaluated using the maximal exercise test and estimated VO2max values, functional capacity using the 6-min walk test (6MWT), and quality of life using the Short Form-36 survey and MacNew Heart Disease Health-related Quality of Life (MacNew) questionnaire. It was determined that the estimated VO2max values statistically significantly improved after treatment (P < 0.05), and both HIIT groups were superior to the MICT group (P < 0.05). Only the HIIT groups achieved the minimal clinically important difference in the 6MWT distance. After treatment, only the MICT group had a statistically significant improvement in quality of life. There was no statistically significant difference between the groups in relation to the improvement in the 6MWT distance and quality of life (P > 0.05). The results of our study showed that both HIIT programs were superior to MICT in improving the maximal exercise capacity of patients with CAD, and the three programs had a similar effect on quality of life.

Effects of Endurance Training on Motor Signs of Parkinson's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Evidence has demonstrated that endurance training (ET) reduces the motor signs of Parkinson's disease (PD). However, there has not been a comprehensive meta-analysis of studies to date.

OBJECTIVE

The aim of this study was to compare the effect of ET versus nonactive and active control conditions on motor signs as assessed by either the Unified Parkinson's Disease Rating Scale part III (UPDRS-III) or Movement Disorder Society-UPDRS-III (MDS-UPDRS-III).

METHODS

A random-effect meta-analysis model using standardized mean differences (Hedges' g) determined treatment effects. Moderators (e.g., combined endurance and physical therapy training [CEPTT]) and meta-regressors (e.g., number of sessions) were used for sub-analyses. Methodological quality was assessed by the Physiotherapy Evidence Database.

RESULTS

Twenty-seven randomized controlled trials (RCTs) met inclusion criteria (1152 participants). ET is effective in decreasing UPDRS-III scores when compared with nonactive and active control conditions (g =  - 0.68 and g =  - 0.33, respectively). This decrease was greater (within- and between-groups average of - 8.0 and - 6.8 point reduction on UPDRS-III scores, respectively) than the moderate range of clinically important changes to UPDRS-III scores (- 4.5 to - 6.7 points) suggested for PD. Although considerable heterogeneity was observed between RCTs (I² = 74%), some moderators that increased the effect of ET on motor signs decreased the heterogeneity of the analyses, such as CEPTT (I² = 21%), intensity based on treadmill speed (I² = 0%), self-perceived exertion rate (I² = 33%), and studies composed of individuals with PD and freezing of gait (I² = 0%). Meta-regression did not produce significant relationships between ET dosage and UPDRS-III scores.

CONCLUSIONS

ET is effective in decreasing UPDRS-III scores. Questions remain about the dose-response relationship between ET and reduction in motor signs.

Can the Six-Minute Walk Test Be Used to Individualize Physical Activity Intensity in Patients with Breast Cancer?

Simple Summary

Physical activity has proven to be effective in breast cancer patients. Appropriate exercise intensity for each patient is necessary to maintain this practice in patients with possible comorbidities and potential adverse events of specific treatments. These programs should be proposed to many patients so to prescribe the adapted program; this will necessitate easy and cost-effective tests. It is useful to use an adapted target heart rate (HR) to prescribe exercise intensity. In this work, we assessed the potential equivalence of the ventilatory threshold HR obtained during a cardiopulmonary exercise test and the HR measured over the last 3 min of the six-minute walk test (6MWT-HR). At baseline, the 6MWT-HR was in good agreement and showed moderate but statistical correlation with the VT-HR in breast cancer patients. The best correlation between these two tests was obtained after the APA program and chemotherapy. These results were independent of body mass index. The 6MWT is useful to prescribe APA programs before and also after chemotherapy concomitant with physical activity.

Abstract

Background: Adapted physical activity (APA) aids breast cancer patients. It is necessary to use an adapted target heart rate (HR) when prescribing exercise intensity. Methods: In total, 138 patients previously included in two published randomized clinical trials underwent the CPET and 6MWT before and after adjuvant therapy. Of these patients, 85 had performed APA, and 53 had received only the usual therapy. HRs were recorded during the two tests. Results: Before starting chemotherapy, good agreement (intraclass correlation (ICC) 0.69; confidence interval at 95% IC_0.95 (0.591–0.769); p < 0.001) and a moderate correlation were evident between the 6MWT-HR and ventilatory threshold HR of the CPET (r = 0.70; p < 0.001). Good agreement and a high positive correlation were noted only in the group who engaged in APA (ICC 0.77; IC_0.95 (0.659–0.848); p < 0.001; r = 0.8; p < 0.01); moderate agreement and a moderate positive correlation were apparent in the control group (ICC 0.57; IC_0.95 (0.329–0.74); p < 0.001; r = 0.6; p < 0.01). The correlations were independent of age and body mass index. Conclusions: The 6MWT-HR can be used to prescribe exercise intensity for breast cancer patients both before and after specific treatment with concomitant APA.

Comparison of High-Intensity Interval Training to Moderate-Intensity Continuous Training in Older Adults: A Systematic Review

High-intensity interval training (HIIT) is emerging as a safe and effective means to combat chronic diseases. The objective of this work was to perform a systematic review of the effect of HIIT interventions in an aging population. Three electronic databases were searched for randomized trials comparing the effect of HIIT and moderate-intensity continuous training in older adults. After a thorough screening process, 15 articles were identified as meeting the inclusion criteria. All studies expressed a comparable or superior effect of HIIT in cardiorespiratory fitness measures. No studies reported a lessened effect of HIIT in comparison with moderate-intensity continuous training. This systematic review demonstrates that HIIT is a useful exercise regimen, which can be used in older adults to increase cardiorespiratory fitness. More research is needed to determine the effects of HIIT in an aging, predominately female population.

Six-minute walk test in cardiac rehabilitation

Six-minute walk test (6MWT) is a simple and safe tool for assessing exercise tolerance in  various  categories  of  patients.  Currently,  6MWT  is  used to assess the functional status of a patient and determine the strategy of increasing physical activity, primarily in patients with reduced exercise tolerance and contraindications for cardiopulmonary exercise  test. The basic requirements for the 6MWT are presented, taking into account the factors affecting its  informativeness  and  accuracy,  as  well  as the interpretation of results. The diagnostic and prognostic value of 6MWT in different categories of patients are discussed. The prospects for 6MWT use in cardiac rehabilitation for planning rehabilitation program, prescribing exercises,  determining  the  risk   of   complications,   and   evaluating the effectiveness  are  considered.  The  limitations  of  6MWT  and  ways to overcome it, as well as directions for further research are presented.

Effects of different percentages of body weight-supported treadmill training in Parkinson’s disease: a double-blind randomized controlled trial

Background/aim

Body weight-supported treadmill training (BWSTT) might have greater effects than conventional treadmill training (TT) in neurological diseases such as Parkinson’s disease (PD). The aim of this study was to evaluate the effects of different percentages of BWSTT on gait, balance, quality of life, and fatigue in PD.

Materials and methods

Thirty-five patients with moderate to advanced PD were randomized into three BWSTT groups according to the supported percentage of body weight: 0% BWSTT (control group; unsupported TT), 10% BWSTT, or 20% BWSTT. Five patients were excluded due to early discharge and 30 patients completed BWSTT sessions lasting 30 min, 5 days a week, for 6 weeks during their inpatient rehabilitation stay. The primary outcome was 6-min walk distance (6MWD). Secondary outcomes were Unified Parkinson’s Disease Rating Scale (UPDRS), Berg Balance Scale (BBS), Nottingham Health Profile (NHP), Fatigue Impact Scale, and Fatigue Severity Scale scores. Measurements were performed before and after the training.

Results

The unsupported TT group demonstrated no significant improvement in the outcome measures after a 6-week training except for BBS and NHP emotional subscores. Moreover, the NHP pain subscore increased in the unsupported TT group after training. The 10% and 20% supported BWSTT groups demonstrated significant improvements in 6MWD (P = 0.004 and P < 0.001, respectively), UPDRS - motor score (P = 0.012 and P = 0.005, respectively), NHP pain subscore (P = 0.003 and P = 0.002, respectively), and fatigue (P = 0.005 for both) after training. The 20% BWSTT provided the highest improvement in balance among the three groups (P < 0.001) and greater relief of fatigue than 10% BWSTT (P = 0.002).

Conclusion

Six weeks of BWSTT improved walking distance and balance ability, relieved fatigue, and additionally reduced pain in patients with moderate to advanced PD.

Aerobic Interval vs. Continuous Training in Patients with Coronary Artery Disease or Heart Failure: An Updated Systematic Review and Meta-Analysis with a Focus on Secondary Outcomes

BACKGROUND

In a previous meta-analysis including nine trials comparing aerobic interval training with aerobic continuous training in patients with coronary artery disease, we found a significant difference in peak oxygen uptake favoring aerobic interval training.

OBJECTIVE

The objective of this study was to (1) update the original meta-analysis focussing on peak oxygen uptake and (2) evaluate the effect on secondary outcomes.

METHODS

We conducted a systematic review with a meta-analysis by searching PubMed and SPORTDiscus databases up to March 2017. We included randomized trials comparing aerobic interval training and aerobic continuous training in patients with coronary artery disease or chronic heart failure. The primary outcome was change in peak oxygen uptake. Secondary outcomes included cardiorespiratory parameters, cardiovascular risk factors, cardiac and vascular function, and quality of life.

RESULTS

Twenty-four papers were identified (n = 1080; mean age 60.7 ± 10.7 years). Aerobic interval training resulted in a higher increase in peak oxygen uptake compared with aerobic continuous training in all patients (1.40 mL/kg/min; p < 0.001), and in the subgroups of patients with coronary artery disease (1.25 mL/kg/min; p = 0.001) and patients with chronic heart failure with reduced ejection fraction (1.46 mL/kg/min; p = 0.03). Moreover, a larger increase of the first ventilatory threshold and peak heart rate was observed after aerobic interval training in all patients. Other cardiorespiratory parameters, cardiovascular risk factors, and quality of life were equally affected.

CONCLUSION

This meta-analysis adds further evidence to the clinically significant larger increase in peak oxygen uptake following aerobic interval training vs. aerobic continuous training in patients with coronary artery disease and chronic heart failure. More well-designed randomized controlled trials are needed to establish the safety of aerobic interval training and the sustainability of the training response over longer periods.

Relationships between heart rate target determined in different exercise testing in COPD patients to prescribed with individualized exercise training

Background

It has been scientifically proven that pulmonary rehabilitation improves exercise tolerance and facilitates the carrying out of daily physical activities. To optimize the physical and physiological benefits, it is necessary to individualize the training intensity for each patient. The aim of this study is to compare the heart rate (HR) responses to three exercise modalities measuring aerobic fitness in chronic obstructive pulmonary disease patients, in order to easily prescribe individual target HRs for endurance training.

Patients and method

Fifty COPD patients (mean age: 60.1±8.5 years) were included in the study. Each patient carried out a cardiopulmonary exercise test, a 6-minute walk test (6MWT) and a 6-minute stepper test (6MST). During these tests, HR was recorded continuously. After the cardiopulmonary exercise test, the HR was noted at the ventilatory threshold (VT) and at the end of the two exercise field tests (6MWT_peak and 6MST_peak). The values of the HR during the last 3 minutes of both field tests were averaged (6MWT₄₅₆ and 6MST₄₅₆). Finally, the HR at 60% of the HR reserve was calculated with the values of the HR measured during 6MWT and 6MST (HRr_60%walk, HRr_60%step).

Results

The HRs measured during the 6MST were significantly higher than those measured during the 6MWT. The HRr_60%step was not significantly different from 6MWT₄₅₆ and 6MWT_peak HR (P=0.51; P=0.48). A significant correlation was observed between 6MWT₄₅₆ and 6MWT_peak (r=0.58). The 6MWT₄₅₆ and 6MWT_peak HR were correlated with HRr_60%step (r=0.68 and r=0.62). The VT could be determined in 28 patients. The HR_VT was not different from 6MWT₄₅₆, 6MWT_peak, and HRr_60%step (P=0.57, P=0.41 and P=0.88) and was correlated to 6MWT₄₅₆, 6MWT_peak, and HRr_60%step (r=0.45, r=0.40, r=0.48).

Conclusion

An individualized target HR for endurance training can be prescribed from the HR measured during routine tests, such as 6MWT or 6MST.

Fixed-distance walk tests at comfortable and fast speed: Potential tools for the functional assessment of coronary patients?

OBJECTIVES

There is ambiguity concerning the walk tests available for functional assessment of coronary patients, particularly for the walking speed. This study explores the psychometric properties of two walking tests, based on fixed-distance tests, at comfortable and fast velocity, in stabilized patients at the end of a cardiac rehabilitation program.

METHODS

At a three-day interval 58 coronary patients (mean age of 64.85±6.03 years, 50 men) performed three walk tests, the first two at a comfortable speed in a random order (6-minute walk test - 6MWT - and 400-metre comfortable walk test - 400mCWT) and the third at a brisk speed (200-metre fast walk test - 200mFWT). A modified Bruce treadmill test was associated at the end of the second phase. Monitored main parameters were: heart rate, walking velocity, VO₂.

RESULTS

Tolerance to the 3 tests was satisfactory. The reliability of the main parameters was good (intraclass correlation coefficient>0.8). The VO₂ concerning 6MWT and 400mCWT were not significantly different (P=0.33) and were lower to the first ventilatory threshold determined by the stress test (P<0.001): 16.2±3.0 vs. 16.5±2.6 vs. 20.7±5.1mL·min^-1·kg^-1 respectively. The VO₂ of the 200mFWT (20.2±3.7) was not different from the first ventilatory threshold.

CONCLUSIONS

400mCWT and 200mFWT are feasible, well-tolerated and reliable. They explore two levels of effort intensity (lower and not different to the first ventilatory threshold respectively). 400mCWT is a possible alternative to 6MWT. Associated with 200mFWT it should allow a better measurement of physical capacities and better customization of exercise training.

Effects of resistance training combined with moderate-intensity endurance or low-volume high-intensity interval exercise on cardiovascular risk factors in patients with coronary artery disease

OBJECTIVES

To determine the effects of resistance training combined with either moderate-intensity endurance or low-volume high-intensity interval training on cardiovascular risk profiles in patients with coronary artery disease.

DESIGN

Factorial repeated-measures study design.

METHODS

Nineteen patients were randomized into moderate-intensity endurance (n = 10) or high-intensity interval (n = 9) groups, and attended 2 supervised exercise sessions a week for 6-months. The first 3-months involved exclusive moderate-intensity endurance or high-intensity interval exercise, after which progressive resistance training was added to both groups for the remaining 3-months. Fitness (VO(2)peak), blood pressure and heart rate, lipid profiles and health related quality of life assessments were performed at pretraining, 3 and 6-months training.

RESULTS

VO(2)peak increased from pretraining to 3-months in both groups (moderate-intensity endurance: 19.8 ± 7.3 vs. 23.2 ± 7.4 ml kg(-1)min(-1); high-intensity interval: 21.1 ± 3.3 vs. 26.4 ± 5.2 ml kg(-1)min(-1), p<0.001) with no further increase at 6-months. Self-evaluated health and high-density lipoprotein were increased following 6-months of moderate-intensity endurance exercise, while all remaining indices were unchanged. Low-volume high-intensity interval exercise did not elicit improvements in lipids or health related quality of life. Blood pressures and heart rates were unchanged with training in both groups.

CONCLUSIONS

Findings from our pilot study suggest improvements in fitness occur within the first few months of training in patients with coronary artery disease, after which the addition of resistance training to moderate-intensity endurance and high-intensity interval exercise elicited no further improvements. Given the importance of resistance training in cardiac rehabilitation, additional research is required to determine its effectiveness when combined with high-intensity interval exercise.

A study of the 200-metre fast walk test as a possible new assessment tool to predict maximal heart rate and define target heart rate for exercise training of coronary heart disease patients

Objective:

To develop a new predictive model of maximal heart rate based on two walking tests at different speeds (comfortable and brisk walking) as an alternative to a cardiopulmonary exercise test during cardiac rehabilitation.

Design:

Evaluation of a clinical assessment tool.

Setting:

A Cardiac Rehabilitation Department in France.

Subjects:

A total of 148 patients (133 men), mean age of 59 ±9 years, at the end of an outpatient cardiac rehabilitation programme.

Main measures:

Patients successively performed a 6-minute walk test, a 200 m fast-walk test (200mFWT), and a cardiopulmonary exercise test, with measure of heart rate at the end of each test. An all-possible regression procedure was used to determine the best predictive regression models of maximal heart rate. The best model was compared with the Fox equation in term of predictive error of maximal heart rate using the paired t-test.

Results:

Results of the two walking tests correlated significantly with maximal heart rate determined during the cardiopulmonary exercise test, whereas anthropometric parameters and resting heart rate did not. The simplified predictive model with the most acceptable mean error was: maximal heart rate = 130 − 0.6 × age + 0.3 × HR200mFWT (R2 = 0.24). This model was superior to the Fox formula (R2 = 0.138). The relationship between training target heart rate calculated from measured reserve heart rate and that established using this predictive model was statistically significant ( r = 0.528, p < 10−6).

Conclusions:

A formula combining heart rate measured during a safe simple fast walk test and age is more efficient than an equation only including age to predict maximal heart rate and training target heart rate.

Walking tests during the exercise training: specific use for the cardiac rehabilitation

Walk tests, principally the six-minute walk test (6mWT), constitute a safe, useful submaximal tool for exercise tolerance testing in cardiac rehabilitation (CR). The 6mWT result reflects functional status, walking autonomy and efficacy of CR on walking endurance, which is more pronounced in patients with low functional capacity (heart failure - cardiac surgery). The 6mWT result is a strong predictor of mortality. However, clinically significant changes and reliability are still subject to debate - probably because of the ambiguity in terms of the target speed (either comfortable or brisk walking). Of the other time-based walk tests, the 2-minute-walk test is the only one applicable during CR, reserved for patients with severe disabilities by its psychometric properties. Fixed-distance tests (principally the 200m fast walk test) and incremental shuttle walking, tests explore higher levels of effort and may represent a safe and inexpensive alternative to laboratory-based tests during CR. These walking tests may be useful for personalizing prescription of training programs. However, the minimum clinically significant difference has not yet been determined. Lastly, walking tests appear to be potential useful tools in promoting physical activity and behavioural changes at home. Thus, validation of other walk tests with better psychometric properties will be necessary.

Reproducibility, validity and responsiveness of the 200-metre fast walk test in patients undergoing cardiac rehabilitation

Objective:

To investigate the reliability, validity and responsiveness of the 200-metre fast walk test in patients with coronary artery disease engaged in a cardiac rehabilitation programme.

Design:

Descriptive study.

Setting:

Tertiary care hospital.

Subjects:

Thirty stable patients with coronary artery disease (51.9 ± 8.7 years), referred to the cardiac rehabilitation department after an acute coronary syndrome.

Intervention:

Not applicable.

Main measures:

Six-minute walk test distance, time to perform the 200-m fast walk test, peak power output of the graded maximal exercise test, before and after the programme; SF-36 quality of life questionnaire at baseline. Walk tests were performed twice at baseline to assess reliability.

Results:

The 200-m fast walk test was highly reliable (ICC = 0.97). It was significantly correlated with the graded maximal exercise test peak power and the 6-minute walk test at baseline ( r = −0.417; P < 0.05; and r = −0.566; P < 0.01, respectively) and after the training programme ( r = −0.460, P < 0.05; and r = −0.926; P < 0.01, respectively). At baseline, there was a strong correlation between the 200-m fast walk test time and the physical component score of the SF-36 ( r = −0.77; P < 0.01), but not between the 200-m fast walk test time and the SF-36 mental component score. Mean 200-m fast walk test time was significantly different between the patients performing ≤90 W ( n = 11) or ≥100 W ( n = 19) at the baseline graded maximal exercise test (121.7 ± 13.6 vs. 115.5 ± 10.1 seconds; P < 0.05). The responsiveness was strong with a standardized response mean at 1.11.

Conclusion:

The 200-m fast walk test is a reliable, valid and responsive high-intensity walk test in patients with coronary artery disease after an acute coronary syndrome. It can thus give additional information to that given by the 6-minute walk test and the graded maximal exercise test.