Pilot investigation of the oxygen demands and metabolic cost of incremental shuttle walking and treadmill walking in patients with cardiovascular disease

Cardiopulmonary response during incremental shuttle walking test in a hallway versus on treadmill in Phase IV cardiac rehabilitation: a cross-sectional study

There is widespread use of incremental shuttle walking test (ISWT) to measure functional capacity in cardiac rehabilitation patients. Due to occasional physical space limitations, an incremental shuttle walking test on a treadmill (ISWT-T) was suggested as an alternative. Knowledge about the cardiopulmonary response between the two tests and the factors associated with the distance achieved in Phase IV cardiac rehabilitation is limited. Thus, the study aims to compare the cardiopulmonary response between ISWT and ISWT-T and investigate the factors associated with distance achieved in both tests. Thirteen participants (66.3 ± 7.3 years, 84.6% males) attending phase IV cardiac rehabilitation participated in repeated measures counterbalanced trials. Each participant performed one ISWT and one ISWT-T separated by seven days. Main outcome measures included peak heart rate (HR), systolic and diastolic blood pressure post-test, distance achieved, respiratory frequency, tidal volume (VT), minute ventilation, respiratory exchange ratio, peak oxygen uptake (VO2PEAK), and secondary outcome measures included height, weight, waist circumference (WC) leg length (LL). There were no significant differences in the cardiopulmonary responses between ISWT and ISWT-T except for VO2PEAK (25.4 ± 5.8 vs 23.7 ± 5.1, p = 0.05, respectively). Age and height were significantly correlated with distance achieved during ISWT, and ISWT-T [age (r = - 0.72, vs. r = - 0.73, p ≤ 0.05, respectively)], [height (r = 0.68, vs. r = 0.68, p ≤ 0.05, respectively)]. LL was only correlated with distance achieved on ISWT-T (r = 0.59, p ≤ 0.05). These findings suggest a similar cardiopulmonary response between the two tests, but doing ISWT in the hallway evoked a higher metabolic demand than doing it on a treadmill. Additionally, distance achieved on both tests was related to height and inversely to age.

Instrumented Assessment of Motor Performance Fatigability During the 6-Min Walk Test in Mildly Affected People With Multiple Sclerosis

There are conflicting results regarding the changes in spatio-temporal gait parameters during the 6-min walk test (6MWT) as indicators of gait-related motor performance fatigability (PF) in people with Multiple Sclerosis (pwMS). To further analyze if gait-related motor PF can be quantified using instrumented gait analysis during the 6MWT, we investigated: (i) whether gait parameters recorded during the first or second minute were more stable and thus the better baseline to assess motor PF and (ii) if the minimum toe clearance (MTC) together with “classical” spatio-temporal gait parameters can be used to quantify motor PF in pwMS. Nineteen mildly affected pwMS [12 women/7 men; 47.8 ± 9.0 years; the Expanded Disability Status Scale (EDSS): 2.7 ± 1.0] and 24 healthy controls (HC; 15 women/9 men; 48.8 ± 7.6 years) completed the 6MWT equipped with inertial measurement units. Data were analyzed using the attractor method to compare the stability of gait parameters and, besides “classical” spatio-temporal gait parameters, the MTC was calculated as a potential new marker for motor PF in pwMS as this was shown in healthy older adults. It was found that (i) gait parameters were more stable in the second than in the first minute and (ii) gait-related motor PF could not be detected based on spatio-temporal gait parameters, including the MTC. Descriptive analysis indicated a decrease in MTC variability, which is assumed to be indicative for motor PF, toward the end of the 6MWT in some pwMS. Future studies should investigate gait parameters for the assessment of motor PF in pwMS recorded during more intense and/or longer walking protocols, taking the level of disability into account. Furthermore, using gait parameters recorded in the first minute of the 6MWT as a baseline for the assessment of motor PF should be avoided.

Clinical outcomes vary between the Shuttle Walk Test and Stress Test in patients with coronary artery disease

Purpose

The purpose of this study was to determine if the Incremental Shuttle Walk Test (ISWT) can elicit similar patient responses as a treadmill stress test in patients with coronary artery disease (CAD).

Methods

Both the stress test and the ISWT were performed by 172 participants, aged 60.67±10.23 years. We screened participants for unstable angina, severe aortic stenosis, uncontrolled hypertension, and excluded if unable to walk on a treadmill. Outcome measures (signs and symptoms) included: i) patient-reported chest pain; ii) patient-reported breathlessness/exhaustion and not being able to keep up with test protocol; and iii) able to reach target HRmax. Additionally, EKG changes during the stress test were monitored for ST changes or arrhythmias.

Results

During the stress test, 15 participants reported chest pain, 23 participants reached target HRmax. No participants reported chest pain and 2 participants reached target HRmax during the ISWT. Participants reporting chest pain had a higher mean BMI and significant difference in METS (p < 0.001) during the stress test and walking distance (p = 0.03) when compared with patients who did not report chest pain during the stress test. Breathlessness and not being able to keep up with protocol were the most commonly reported in both tests. Changes in EKG were observed in 38 participants in the stress test.

Conclusion

A maximal effort stress test is better at eliciting ischemic signs and symptoms and a superior tool for diagnosis of progression or severity of CAD than the ISWT. Appropriate selection of exercise tests is important in the clinical setting.

Exercise-induced desaturation in subjects with non-cystic fibrosis bronchiectasis: laboratory-based tests versus field-based exercise tests

OBJECTIVE

To investigate the validity of field walking tests to identify exercise-induced hypoxemia and to compare cardiorespiratory responses and perceived effort between laboratory-based and field-based exercise tests in subjects with bronchiectasis.

METHODS

This was a cross-sectional study involving 72 non-oxygen-dependent participants (28 men; mean age = 48.3 ± 14.5 years; and mean FEV1 = 54.1 ± 23.4% of the predicted value). The participants underwent cardiopulmonary exercise testing (CPET) on a treadmill and constant work-rate exercise testing (CWRET) on the same day (1 h apart). In another visit, they underwent incremental shuttle walk testing (ISWT) and endurance shuttle walk testing (ESWT; 1 h apart). Desaturation was defined as a reduction in SpO2 ≥ 4% from rest to peak exercise.

RESULTS

CPET results were compared with ISWT results, as were CWRET results with ESWT results. There was no difference in the magnitude of desaturation between CPET and ISWT (-7.7 ± 6.3% vs. -6.6 ± 5.6%; p = 0.10) and between CWRET and ESWT (-6.8 ± 5.8% vs. -7.2 ± 6.3%; p = 0.50). The incremental tests showed an agreement in the magnitude of desaturation in the desaturation and no desaturation groups (42 and 14 participants, respectively; p < 0.01), as did the endurance tests (39 and 16 participants; p < 0.01). The magnitude of desaturation was similar among the participants who did or did not reach at least 85% of the maximum predicted HR.

CONCLUSIONS

Field exercise tests showed good precision to detect desaturation. Field tests might be an alternative to laboratory tests when the clinical question is to investigate exercise-induced desaturation in subjects with bronchiectasis.

Validity of the Incremental Shuttle Walk Test to Assess Exercise Safety When Initiating Cardiac Rehabilitation in Low-Resource Settings

PURPOSE

To evaluate the validity of the Incremental Shuttle Walk Test (ISWT) for determining risk stratification in cardiac rehabilitation (CR).

METHODS

This is a cross-sectional study at a major CR center in a middle-income country. Clinically stable adult cardiac patients underwent an ISWT and an exercise test (ET), wore a pedometer for 7 d, and completed the Godin-Shepherd Leisure-Time Physical Activity Questionnaire. Metabolic equivalents of task (METs) achieved on the ISWT were calculated.

RESULTS

One hundred fifteen patients were evaluated. The mean ± standard deviation distance on the ISWT was 372.70 ± 128.52 m and METs were 5.03 ± 0.62. The correlation of ISWT distance with ET METs (7.57 ± 2.57), steps/d (4556.71 ± 3280.88), and self-reported exercise (13.08 ± 15.19) was rs = 0.61 (P < .001), rs = 0.37 (P < .001), and rs = 0.20 (P = .031), respectively. Distance on the ISWT accurately predicted METs from the ET (area under the receiver operating characteristic curve = 0.774). The ability to walk ≥410 m on the ISWT predicted, with a specificity of 81.5% and a sensitivity of 65.6%, a functional capacity of ≥7 METs on ET.

CONCLUSION

The ISWT is an alternative way to evaluate functional capacity in CR and can contribute to the process of identifying patients at low risk for a cardiac event during exercise at moderate intensity.

Predicting the rate of oxygen consumption during the 3-minute constant-rate stair stepping and shuttle tests in people with chronic obstructive pulmonary disease

Background

The 3-minute constant-rate stair stepping (3-min CRSST) and constant-speed shuttle tests (3-min CSST) were developed to assess breathlessness in response to a standardized exercise stimulus. Estimating the rate of oxygen consumption (V’O₂) during these tests would assist clinicians to relate the stepping/shuttle speeds that elicit breathlessness to daily physical activities with a similar metabolic demand. This study: (I) developed equations to estimate the V’O₂ of these tests in people with chronic obstructive pulmonary disease (COPD); and (II) compared the newly developed and American College of Sports Medicine (ACSM) metabolic equations for estimating the V’O₂ of these tests.

Methods

This study was a retrospective analysis of people with COPD who completed a 3-min CRSST (n=98) or 3-min CSST (n=69). Multivariate linear regression estimated predictors (alpha <0.05) of V’O₂ to construct COPD-specific metabolic equations. The mean squared error (MSE) of the COPD-specific and ACSM equations was calculated and compared. Bland-Altman analyses evaluated level of agreement between measured and predicted V’O₂ using each equation; limits of agreement (LoA) and patterns of bias were compared.

Results

Stepping rate/shuttle speed and body mass were identified as significant predictors of V’O₂. The MSE of the COPD-specific equations was 0.05 L·min⁻¹ for both tests. Mean difference between measured and predicted V’O₂ was 0.00 L·min⁻¹ (95% LoA −0.46, 0.46) and 0.00 L·min⁻¹ (95% LoA −0.44, 0.44) for the 3-min CRSST and 3-min CSST, respectively. For the ACSM metabolic equations, the MSE was 0.10 L·min⁻¹ and 0.18 L·min⁻¹ for the 3-min CRSST and 3-min CSST, respectively. The ACSM metabolic equations underestimated V’O₂ of the 3-min CRSST by −0.18 L·min⁻¹ (95% LoA −0.68, 0.32), and overestimated V’O₂ of the 3-min CSST by 0.35 L·min⁻¹ (95% LoA −0.14, 0.84).

Conclusions

This study presents metabolic equations to predict V’O2 of the 3-min CRSST and 3-min CSST for people with COPD that are more accurate than the ACSM metabolic equations.

Energetics of male field-sport athletes during the 3-min all-out test for linear and shuttle-based running

PURPOSE

All-out, non-steady state running makes for difficult comparisons regarding linear and shuttle running; yet such differences remain an important distinction for field-based sports. The purpose of the study was to determine whether an energetic approach could be used to differentiate all-out linear from shuttle running.

METHODS

Fifteen male field-sport athletes volunteered for the study (means ± SD): age, 21.53 ± 2.23 years; height, 1.78 ± 0.68 m; weight, 83.85 ± 11.73 kg. Athletes completed a graded exercise test, a 3-min linear all-out test and two all-out shuttle tests of varied distances (25 m and 50 m shuttles).

RESULTS

Significant differences between the all-out tests were found for critical speed (CS) [F(8.97), p < 0.001), D' (finite capacity for running speeds exceeding critical speed) [F(7.83), p = 0.001], total distance covered [F(85.31), p < 0.001], peak energetic cost ([Formula: see text]) [F(45.60), p < 0.001], peak metabolic power ([Formula: see text]) [F(23.36), p < 0.001], average [Formula: see text] [F(548.74), p < 0.001], maximal speed [F(22.87), p < 0.001] and fatigue index [F(3.93), p = 0.027]. Non-significant differences were evident for average [Formula: see text] [F(2.47), p = 0.097], total [Formula: see text] [F(0.86), p = 0.416] and total [Formula: see text] [F(2.11), p = 0.134].

CONCLUSIONS

The energetic approach provides insights into performance characteristics that differentiate linear from shuttle running, yet surprising similarities between tests were evident. Key parameters from all-out linear and shuttle running appear to be partly interchangeable between tests, indicating that the final choice between linear and shuttle testing should be based on the requirements of the sport.

Effects of exercise-based cardiac rehabilitation on cardiorespiratory fitness: A meta-analysis of UK studies

BACKGROUND

Exercise-based cardiac rehabilitation can promote meaningful improvements in cardiorespiratory fitness (fitness) but the magnitude of such improvements varies according to local characteristics of exercise programmes. We aimed to determine if cardiac rehabilitation (CR), as practised in the United Kingdom (UK), could promote meaningful changes in fitness and to identify programme characteristics which may moderate these changes.

METHODS

Electronic and manual searches to identify UK CR studies reporting fitness at baseline and follow up. Change in fitness (Δfitness) was expressed as mean difference (95% CI) and effect size (ES). A random effects model was used to calculate the mean estimate for change in Δfitness. Between-group heterogeneity was quantified (Q) and investigated using planned sub-group analyses.

RESULTS

We identified n=11 studies containing 16 patient groups (n=1 578) which used the incremental shuttle walking test (ISWT) (distance walked) to assess fitness. The overall mean estimate for Δfitness showed a significant increase in distance walked (ES=0.48, P<0.001), but this estimate was highly heterogeneous (Q=77.1, P<0.001, I(2)=81%). Sub-group analyses showed significantly greater ES (Q=3.94, P=0.046) for Δfitness in patients prescribed n>12 exercise sessions compared with those receiving n≤12 sessions.

CONCLUSION

We found significant increases in fitness (based on ISWT) in patients attending exercise-based CR in the UK. However, UK studies provide approximately one-third of the exercise "dose", and produce gains in fitness less than half the magnitude reported in international studies.

Reference values for the incremental shuttle walk test in patients with cardiovascular disease entering exercise-based cardiac rehabilitation

The incremental shuttle walk test (ISWT) is used to assess functional capacity of patients entering cardiac rehabilitation. Factors such as age and sex account for a proportion of the variance in test performance in healthy individuals but there are no reference values for patients with cardiovascular disease. The aim of this study was to produce reference values for the ISWT. Participants were n = 548 patients referred to outpatient cardiac rehabilitation who underwent a clinical examination and performed the ISWT. We used regression to identify predictors of performance and produced centile values using the generalised additive model for location, scale and shape model. Men walked significantly further than women (395 ± 165 vs. 269 ± 118 m; t = 9.5, P < 0.001) so data were analysed separately by sex. Age (years) was the strongest predictor of performance in men (β = -5.9; 95% CI: -7.1 to -4.6 m) and women (β = -4.8; 95% CI: -6.3 to 3.3). Centile curves demonstrated a broadly linear decrease in expected ISWT values in males (25-85 years) and a more curvilinear trend in females. Patients entering cardiac rehabilitation present with highly heterogeneous ISWT values. Much of the variance in performance can be explained by patients' age and sex. Comparing absolute values with age-and sex-specific reference values may aid interpretation of ISWT performance during initial patient assessment at entry to cardiac rehabilitation.

Does the Incremental Shuttle Walking Test require maximal effort in healthy subjects of different ages?

OBJECTIVE

To evaluate if the Incremental Shuttle Walking Test (ISWT) requires maximal effort in healthy subjects of different ages.

DESIGN

Cross-sectional.

SETTING

University-based research laboratory.

PARTICIPANTS

331 healthy subjects separated into six groups according to age: G1, 18 to 28 years; G2, 29 to 39 years; G3, 40 to 50 years; G4, 51 to 61 years; G5, 62 to 72 years and; G6, 73 to 83 years.

MAIN OUTCOME MEASURES

Two ISWTs were performed and participants were permitted to run and to exceed 12 levels during the test, if necessary. Heart rate (HR) and symptoms of dyspnoea and fatigue were recorded before and after the test, and the percentage of age-predicted maximal HR (HRmax) was calculated. Maximal effort was defined as HRmax >90% of age-predicted HRmax.

RESULTS

Almost 31% of the subjects exceeded 12 levels in the ISWT. At the end of the test, all groups presented a median [interquartile range] HR greater than 90% of HRmax (G1: 100 [95 to 104]; G2: 100 [96 to 105]; G3: 103 [97 to 108]; G4: 99 [91 to 106]; G5: 96 [87 to 106] and G6: 96 [91 to 109]% HRmax). Regarding symptoms, all groups showed higher values after the test (P<0.05). A multiple logistic regression analysis identified female gender, older age and a lower HR before the test as determinants of not achieving 90% of HRmax at the end of the test.

CONCLUSIONS

The ISWT requires maximal effort in healthy individuals, but for that it is necessary to extend the test beyond twelve levels. Female gender, older age and lower heart rate before the test are the determinants of not reaching maximal effort.