Long-term reliability of the incremental shuttle walking test in clinically stable cardiovascular disease patients

Feasibility of home-based cardiac rehabilitation in frail older patients: a clinical perspective

(A) BACKGROUND

Home-based cardiac rehabilitation (CR) is an attractive alternative for frail older patients who are unable to participate in hospital-based CR. Yet, the feasibility of home-based CR provided by primary care physiotherapists (PTs) to these patients remains uncertain.

(B) OBJECTIVE

To investigate physiotherapists' (PTs) clinical experience with a guideline-centered, home-based CR protocol for frail older patients.

(C) METHODS

A qualitative study examined the home-based CR protocol of a randomized controlled trial. Observations and interviews of the CR-trained primary care PTs providing home-based CR were conducted until data saturation. Two researchers separately coded the findings according to the theoretical framework of Gurses.

(D) RESULTS

The enrolled PTs (n = 8) had a median age of 45 years (IQR 27-57), and a median work experience of 20 years (IQR 5-33). Three principal themes were identified that influence protocol-adherence by PTs and the feasibility of protocol-implementation: 1) feasibility of exercise testing and the exercise program; 2) patients' motivation and PTs' motivational techniques; and 3) interdisciplinary collaboration with other healthcare providers in monitoring patients' risks.

(E) CONCLUSION

Home-based CR for frail patients seems feasible for PTs. Recommendations on the optimal intensity, use of home-based exercise tests and measurement tools, and interventions to optimize self-regulation are needed to facilitate home-based CR.

Incremental shuttle walking test to assess functional capacity in cardiac rehabilitation: a narrative review

Background/Aims

Low functional capacity has been recognised to be the most important predictor of overall mortality compared to all other cardiovascular risk factors in patients with cardiovascular disease. Walk tests, such as the incremental shuttle walking test and the 6-Minute Walk Test, are used to assess functional capacity in patients, the effectiveness of a cardiac rehabilitation programme and the prognosis of cardiovascular diseases. The aim of this review was to provide a narrative review of the literature and identify the key features of the incremental shuttle walking test as a measure of functional capacity testing in cardiac rehabilitation patients.

Methods

The PubMed, MEDLINE, Elsevier and Google Scholar databases were searched for relevant scientific articles published up to March 2021 with no restriction on start day. The key words defined by researchers were ‘incremental shuttle walking test’, ‘exercise test’, ‘functional capacity’, ‘cardiovascular disease’, ‘cardiac rehabilitation’, ‘reliability’ ‘prediction; ‘walk tests’. A final set of 31 articles was included in this narrative review.

Results

Evidence-based findings suggest that the incremental shuttle walking test is a valid, reliable, sensitive, useful tool for detecting and predict cardiorespiratory capacity.

Conclusions

Clinicians can be confident that they can use the incremental shuttle walking test to monitor changes in functional capacity in patients with cardiovascular disease.

Effects of multicomponent exercise training intervention on hemodynamic and physical function in older residents of long-term care facilities: A multicenter randomized clinical controlled trial

OBJECTIVES

To assess hemodynamic and physical function responses during a two-month multicomponent group exercise program (MCEP) in residents of long-term care facilities.

METHODS

40 older long-term care residents were randomly allocated equally to an intervention (IG; n = 20; 80 ± 7 years) and control group (CG; n = 20; 79 ± 7 years); they all submitted to hemodynamic (blood pressure and heart rate) and functional assessments before and after the MCEP. The IG performed a twice-weekly, two-months multicomponent exercise program composed of functional mobility, balance, muscle strength, and flexibility exercises; while the CG did not perform any exercise intervention.

RESULTS

There was a statistically significant decrease in systolic blood pressure (7.25 ± 14.64 mmHg; t = 2.2; effect size = 0.34; p < 0.05) following a two-month MCEP as compared with baseline. In all functional measurements (balance, mobility) were significantly improved after the MCEP (p < 0.05).

DISCUSSION

These data indicate that a two-month MCEP can improve systolic blood pressure and functionality in older residents of long-term care facilities.

Lower Lean Mass Is Associated with Greater Arterial Stiffness in Patients with Lower Extremity Artery Disease

Background: Arterial stiffness is independently associated with lower extremity artery disease (LEAD). Although obesity is already known as an independent cardiovascular risk factor, it was found that, paradoxically, in patients diagnosed with cardiovascular disease, an increase in body mass index (BMI) was associated with a decrease in mortality. However, the underlying mechanism of this paradoxical association remain uncertain. In this study, we firstly hypothesize that arterial stiffness correlates with body mass; secondly, the underlying mechanism of the association for patients with LEAD is individual body composition, in particular, lean mass. Methods: The present study was performed as a single-center, prospective, observational analysis. A total of 412 patients with current or previously diagnosed LEAD (Rutherford Classification 2–4) were included, the cfPWV and AIx were measured as indices of arterial stiffness, and a body composition assessment was performed. Results: In male patients, there was a significantly negative correlation between the AIx and lean mass coefficient (p = 0.004, 95% CI: −0.28 (−0.48–0.09)). Conclusion: For patients with peripheral arterial disease, our data show that lower lean mass in male patients is associated with increased arterial stiffness as measured by the AIx. Therefore, progressive resistance training may be beneficial for the reduction in arterial stiffness in PAD patients in secondary prevention.

ECG changes during ISWTs in adult patients commencing CR: a retrospective case note review

The incremental shuttle walk test (ISWT) is a valid, reliable submaximal exercise test used in the assessment of patients prior to cardiac rehabilitation (CR). Simultaneous electrocardiogram (ECG) measurements would provide important information on the safety of the test, and adequacy of subsequent cardiac risk stratification. Risk stratification is recommended to assess patients' suitability for cardiac rehabilitation. For example, ST-segment depression >2 mm from baseline during testing would place a person in a high-risk category. However, such ECG measurements are rarely undertaken in clinical practice. The aim of the study was to investigate the incidence of ECG changes during an ISWT, and report on the possible impact of these findings on subsequent cardiac risk stratification. A retrospective case note review was undertaken for the year 2017. Baseline clinical characteristics from eligible patients were gathered including those with ischaemic heart disease, heart failure, transplant and valve replacement, along with ECG measurements during the ISWT. The impact of ECG findings on cardiac risk stratification was calculated, based on risk stratification developed by the American Association of Cardiovascular and Pulmonary Rehabilitation. The safety of the ISWT was measured by the absence of major ECG changes. Data were gathered for 295 patients. Minor ECG changes were identified during the ISWT in 189 patients (64.1%), with no major changes. The presence of silent myocardial ischaemia (ST-segment depression) had an impact on cardiac risk stratification in 27 patients. There was a statistically significant positive association between ST-segment depression with cardiac risk stratification (p<0.001). In conclusion, the ISWT is safe in terms of ECG changes. The impact of ECG findings on cardiac risk stratification is significant and worthy of further consideration.

Comparison of heart rate response and heart rate recovery after step test among smoker and non-smoker athletes

BACKGROUND

Exercise performance depend on the ability of the cardiovascular system to respond to a wide range of metabolic demands and physical exertion.

OBJECTIVES

To investigate the habitual smoking effects in heart rate response and heart rate recovery after step test in athletes.

METHODS

Seventy-eight physically healthy active athletes (45 non-smokers and 33 smokers) aging 27±8 years old, participated in this study. All participants completed the International Physical Activity Questionnaire and performed the six-minute step test. Cardiovascular parameters such (resting heart rate, peak heart rate, heart rate at 1 min after testing, heart rate recovery, recovery time, blood pressure at rest, and post-testing blood pressure) were recorded.

RESULTS

Smoker-athletes had higher resting heart rate (76 ± 9bpm vs. 72 ± 10bpm, p<0.05), maximum heart rate (154 ± 18bpm vs. 147 ± 17bpm, p<0.05) and recovery time (7min 25sec ± 6min 31sec vs. 4min 21sec ± 4min 30sec, p<0.05) than non-smoker athletes. Scores from the IPAQ were approximately the same (M=7927 ± 10303, M= 6380 ± 4539, p<0.05).

CONCLUSION

Smoking was found to affect athletes' cardiovascular fitness. The change of the athletes' heart rate recovery and recovery time contributes to the adaptation of cardiovascular function in training requirements.

Eight-week equipment-based Pilates exercises positively affects quality of life, and functional capacity in non-active adult women: a randomized controlled trial

BACKGROUND

The Pilates exercises are popular for muscle conditioning among women. However, the effects on conditioning of healthy non-active adult women due to Pilates practicing are not fully explained. The aim of this randomized controlled trial was to assess the effects of equipment-based Pilates exercises on the percentage of body fat, weight, body mass index (BMI), functional capacity, and quality of life of adult healthy women.

METHODS

Seventy-eight non-active women were randomly assigned to 2 groups (Pilates or Control). The Pilates group performed a total of 16 exercise sessions (60 minutes each, performed twice a week for 8 consecutive weeks). The control group was instructed to perform no exercise. Percentage of body fat (DXA scans), weight, BMI, distance covered in the incremental shuttle walk test, maximal oxygen uptake (VO<inf>2max</inf>), and quality of life (SF-36 scores) were analyzed.

RESULTS

There were no significant between-group differences at baseline, but significant group-by-time interaction was observed for Pilates group postintervention. Higher distance covered (P=0.01), VO<inf>2max</inf> (P=0.04), and quality of life (P=0.04) were observed after the intervention compared to the control group. No differences were observed for body composition.

CONCLUSIONS

Two months of equipment-based Pilates training improved functional capacity and quality of life in healthy adult women.

Reliability and responsiveness of incremental shuttle walk test to estimate exercise capacity in patients with pulmonary arterial hypertension

The purpose of the present study was to evaluate the reliability and responsiveness of the incremental shuttle walk test (ISWT) to estimate exercise capacity in patients with pulmonary arterial hypertension (PAH). This was a cross-sectional longitudinal study performed on stable PAH patients (n=30, mean age ± standard deviation, 60±13.6 years) with World Health Organization functional class II & III. Reliability was assessed by comparing the distance covered between ISWT-1 (initial) and ISWT-2 (retest). Responsiveness was determined by comparing the distance covered in the ISWT-3 post pulmonary rehabilitation (PR) to the ISWT-1. The distance covered between ISWT-1 (177±87.85 m) and ISWT-2 (191.67±96.39 m) was not statistically significant. The result of the relative reliability has shown to be excellent with an intraclass correlation coefficient (ICC2,1= 0.98, 95%CI = 0.95-0.99). Absolute reliability was evaluated through the standard error of the measurement and minimal detectable change at a 95% confidence interval (MDC95) were 12.29 and 33.9 m, respectively. Bland Altman plot showed good agreement between the two ISWTs. Following PR, the effect size (ES=0.78) and standardised response mean (SRM=1.50) were moderate and large respectively. ISWT is considered to be a reliable and responsive measure to estimate exercise capacity in patients with PAH. The ISWT may be considered a suitable alternative tool over a 6-min walk test and in the absence of equipment availability or expertise for conducting cardiopulmonary exercise test for the assessment of exercise capacity in these patients.

Reliability, Validity, and Responsiveness of the Incremental Shuttle Walk Test in Patients With Interstitial Lung Disease

PURPOSE

To determine the reliability, validity, and responsiveness of the incremental shuttle walk test (ISWT) in patients with interstitial lung disease (ILD).

METHODS

This was a cross-sectional longitudinal study. Patients (n = 27, 10 males; mean age ± SD, 61 ± 9.8 y) with ILD of any etiology, who participated in an outpatient pulmonary rehabilitation (PR) program, were recruited. Reliability was determined by comparing the distance covered in meters between the ISWT-1 and the ISWT-2. Validity was assessed by correlating the distance covered in the ISWT-1, with the maximum oxygen consumption ((Equation is included in full-text article.)O2max) obtained through cardiopulmonary exercise testing and distance covered during the 6-min walk test (6MWT). Responsiveness was assessed by comparing the distance covered in the ISWT-3, undertaken after the completion of PR, to the ISWT-1.

RESULTS

The distance covered was equivalent between the ISWT-1 (216.7 ± 64.9 m) and the ISWT-2 (220.7 ± 67.3 m), with an excellent intraclass correlation coefficient (ICC2,1 = 0.91; 95% CI, 0.81-0.95). The standard error of measurement and minimal detectable change at the 95% CI (MDC95) values for the ISWT were 19.5 m and 53.9m, respectively. There were significant correlations between the distance covered on the ISWT and (Equation is included in full-text article.)O2max (r = 0.79, P < .0001) and the distance covered on the 6MWT (r = 0.76, P < .0001). Following PR, the change in the ISWT distance showed large effect size (ES = 0.85) and standardized response mean (SRM = 1.58).

CONCLUSIONS

The ISWT is a reliable, valid, and responsive measure of estimated functional capacity in patients with ILD.

Determinants of walking fitness in patients with heart failure attending cardiac rehabilitation

Introduction

Patients with heart failure (HF) attending cardiac rehabilitation (CR) benefit in terms of improved quality of life, physical fitness and reduced hospital admissions. Too few patients with HF attend CR and little data exist on the characteristics of those who do especially in respect of physical fitness. This study evaluates the extent by which clinical and demographic factors determine walking fitness in patients with a primary diagnosis of HF.

Methods

Clinical data from the British Heart Foundation National Audit of Cardiac Rehabilitation identified 1519 patients with HF who completed an incremental shuttle walk test (ISWT). Stepwise regression accounting for age, gender and multiple potential confounders assessed their contribution to total walking distance.

Results

Mean age was 64.5 (SD 12.70) years with a range of ISWT distances across gender and associated comorbidities from 215 to 282 m. Walking distance reduced by 4.9 m for each year increase in age above mean age (p<0.001). After accounting for confounders, females walked 42.1 m less than males (p≤ 0.001). Pulmonary disease and the existence of depression was associated with a 39.3 and 52.2 m reduction in walking distance, respectively. Body mass index >30 was associated with 28.5 m reduction in walking distance (p<0.001). HF severity failed to improve the regression model fit or achieve significance in the analysis.

Conclusions

Age, gender and the presence of pulmonary disease or depression were highly significant factors in predicting walking fitness in patients with HF. The study also produced a set of reference values based on these four factors to aid the interpretation of walking fitness in patients with HF.

Is Exercise Prescription in Cardiac Rehabilitation Influenced by Physical Capacity or Cardiac Intervention?

This study investigated the influence of cardiac intervention and physical capacity of individuals attending an Australian outpatient cardiac rehabilitation program on the initial exercise prescription. A total of 85 patients commencing outpatient cardiac rehabilitation at a major metropolitan hospital had their physical capacity assessed by an incremental shuttle walk test, and the initial aerobic exercise intensity and resistance training load prescribed were recorded. Physical capacity was lower in surgical patients than nonsurgical patients. While physical capacity was higher in younger compared with older surgical patients, there was no difference between younger and older nonsurgical patients. The initial exercise intensity did not differ between surgical and nonsurgical patients. This study highlights the importance of preprogram exercise testing to enable exercise prescription to be individualized according to actual physical capacity, rather than symptoms, comorbidities and age, in order to maximize the benefit of cardiac rehabilitation.

What factors are associated with patients walking fitness when starting cardiac rehabilitation?

INTRODUCTION

Patients with heart failure (HF) are now a priority group for cardiac rehabilitation (CR). A fundamental component of CR is increasing physical fitness through exercise training. Even though studies show fitness benefits, there is little evidence in routine populations of individual factors that may influence fitness. This study aims to evaluate the extent to which demographics and clinical measures predict physical fitness in patients with HF and develop reference values to guide practice.

METHODS

Data from the National Audit Cardiac Rehabilitation (NACR) was analysed. 2047 patients (73% male) with HF completed an incremental shuttle walk test (ISWT). Backward regression accounting for patient characteristics and new comorbidity groups were used to identify predictors of distance using ISWT. Reference values were produced from the percentiles of the ISWT distance.

RESULTS

Population age was 64.43 years (12.39 SD) with an average ISWT distance of 278.57 m (SD 158.57). Demographics, risk factors and comorbidities explained 26% of the variance in distance (adjusted R2 = 0.256, p value < 0.001). Diuretics (-33.01 m ±8.07 SD) and socioeconomic status (9.12 m ±2.91 SD) were significant predictors of baseline walking fitness. Furthermore, respiratory obstructions, musculoskeletal issues and metabolic diseases were associated with reduced walking distance of 29.8 m, 26.6 m and 18.4 m respectively.

CONCLUSION

Use of diuretics, socioeconomic status and presence of comorbidities were significant predictors of walking performance in patients with HF who attended CR and were fit enough to carry out an ISWT. Reference values, to aid clinical practice, were developed that included age, gender and comorbidities status.

Interpreting Meaningful Change in the Distance Walked in the 10-Metre ISWT in Cardiac Rehabilitation

BACKGROUND

The interpretability of change in exercise test scores is an important measurement property. This study aimed to provide a framework for the interpretation of individual change scores of the 10metre incremental shuttle walk test (ISWT) in cardiac rehabilitation.

METHODS

In a quantitative pre-post design study, 52 patients who were referred to a hospital outpatient department for cardiac rehabilitation participated in this study. Participants completed two ISWTs prior to cardiac rehabilitation. Post cardiac rehabilitation, participants completed a global rating of change score and two ISWTs. Change scores were analysed for smallest detectable change (SDC) and minimum important change (MIC).

RESULTS

The SDC for an individual was 47 metres. The predicted MIC for participants to report an improvement ranged from 70 to 92 metres. The predicted MIC for participants who did not report a deterioration in the global rating of change (i.e., those who reported unchanged or improved) ranged from 16 to 42 metres.

CONCLUSIONS

The MIC for patients who report any improvement in physical fitness and functional capacity is 70 metres. These results suggest that over an 8-week program, patients would need to improve by at least seven shuttles to perceive an improvement in their physical fitness and functional capacity. Patients with small increases in the 10-metre ISWT distance may still report deterioration in their physical fitness and functional capacity.

Does peripheral arterial occlusive disease influence muscle strength and exercise capacity in COPD patients?

Background

The pathophysiology of chronic obstructive pulmonary disease (COPD) is complex and understanding of it has been changing in recent years, with regard to its multisystemic manifestations, especially peripheral dysfunction and its influence on intolerance to exercise.

Objectives

To evaluate the relationship between peripheral arterial occlusive disease (PAOD) and peripheral muscle strength and exercise capacity in COPD patients.

Methods

We conducted a cross-sectional study of 35 patients with COPD who were evaluated with the Ankle-Brachial Index, handgrip strength test, 1 repetition maximum (1RM) of knee extensors and flexors, and distance covered in the incremental shuttle walking test (dISWT).

Results

COPD patients with coexisting PAOD had lower dominant handgrip strength test results (33.00 vs. 26.66 kgf, p = 0.02) and worse performance in the dISWT (297.32 vs. 219.41 m, p = 0.02) when compared to the COPD patients without PAOD. Strong correlations were found between the result of the handgrip strength test and both the dISWT (r = 0.78; p < 0.001) and the 1RM/knee extension (r = 0.71; p = 0.03); and also between the dISWT and both the 1RM/knee extension (r = 0.72; p = 0.02) and the 1RM/knee flexion (r = 0.92; p < 0.001). The linear regression model showed that the dISWT variable alone explains 15.3% of the Ankle-Brachial Index result (p = 0.01).

Conclusion

COPD patients with PAOD exhibit reduced muscle strength and lower exercise capacity than COPD patients without PAOD.

Validity, responsiveness and minimum clinically important difference of the incremental shuttle walk in idiopathic pulmonary fibrosis: a prospective study

The incremental shuttle walk (ISW) is well validated in COPD but limited psychometric data restrict its use in idiopathic pulmonary fibrosis (IPF). Study 1: 50 patients performed the ISW and 6 min walk test (6MWT). Study 2: 72 patients completed the ISW before and after pulmonary rehabilitation (PR). The ISW correlated strongly with 6MWT distance (r=0.81,p<0.0001). Mean (95% confidence interval) improvement in ISW with PR was 54 (38 to 70) m with an effect size of 0.29. Distribution-based and anchor-based minimum clinically important difference (MCID) estimates ranged from 31 to 46 m. The ISW is valid and responsive in IPF, with an anchor-based MCID estimate similar to that observed in chronic obstructive pulmonary disease.

TRIAL REGISTRATION NUMBER

Pre-results; NCT02530736, NCT02436278.

Evaluation of determinants of walking fitness in patients attending cardiac rehabilitation

AIM

This study aims to investigate the ability of patients' baseline characteristics to predict the distance walked during the incremental shuttle walk test (ISWT) in the cardiac rehabilitation (CR) population and to produce reference values to guide practice.

METHODS

Secondary analysis was conducted on National Audit Cardiac Rehabilitation data collected between 2010 and 2015. Patients (n=8863) were included if they were aged ≥18 years and had a recorded ISWT score assessed before starting CR. Stepwise regression was used to identify factors predicting the ISWT distance. Age, gender, body mass index, height, weight; presence of hypertension, dyslipidemia or diabetes; smoking and physical activity were independent variables. ISWT distance was the dependent variable. The 25th, 50th and 75th percentiles of the ISWT distance were used as reference values.

RESULTS

Age and gender explained 27% of the variance of the distance covered in the ISWT (R2=0.27, adjusted R2=0.27,Standard Error of the Estimate (SEE) = 148.7, p<0.001). Reference values using age and gender categories were developed.

CONCLUSION

Age and gender were the significant factors for predicting the walking fitness in the CR population, with age being the best predictor. The age and gender reference values produced represent a potentially valuable tool to be used in the clinical setting.

Reliability and validity of an audio signal modified shuttle walk test

Background:

The audio signal in the conventionally accepted protocol of shuttle walk test (SWT) is not well-understood by the patients and modification of the audio signal may improve the performance of the test.

Objectives:

The aim of this study is to study the validity and reliability of an audio signal modified SWT, called the Singla-Richa modified SWT (SWT_SR), in healthy normal adults.

Patients and Methods:

In SWT_SR, the audio signal was modified with the addition of reverse counting to it. A total of 54 healthy normal adults underwent conventional SWT (CSWT) at one instance and two times SWT_SR on the same day. The validity was assessed by comparing outcomes of the SWT_SR to outcomes of CSWT using the Pearson correlation coefficient and Bland–Altman plot. Test-retest reliability of SWT_SR was assessed using the intraclass correlation coefficient (ICC). The acceptability of the modified test in comparison to the conventional test was assessed using Likert scale.

Results:

The distance walked (mean ± standard deviation) in the CSWT and SWT_SR test was 853.33 ± 217.33 m and 857.22 ± 219.56 m, respectively (Pearson correlation coefficient - 0.98; P < 0.001) indicating SWT_SR to be a valid test. The SWT_SR was found to be a reliable test with ICC of 0.98 (95% confidence interval: 0.97–0.99). The acceptability of SWT_SR was significantly higher than CSWT.

Conclusions:

The SWT_SR with modified audio signal with reverse counting is a reliable as well as a valid test when compared with CSWT in healthy normal adults. It better understood by subjects compared to CSWT.

Reproducibility of the incremental shuttle walk test for women with morbid obesity

OBJECTIVE

The incremental shuttle walk test (ISWT) is a valuable tool for the assessment of functional capacity. However, few studies have used the ISWT in individuals with obesity or have determined its reproducibility in this population.

PURPOSE

The aim of the present study was to evaluate the reproducibility of the ISWT in women with morbid obesity.

METHODS

Twenty-three women with a body mass index >40 kg/m(2) (mean age: 39.1 ± 7.7) performed the ISWT twice on the same day.

RESULTS

The mean distance traveled was 313.3 ± 100.2 m on the first test and 322.5 ± 98.9 on the second test, with no significant difference between tests. The intraclass correlation coefficient (0.91) indicated excellent reproducibility. Reliability determined through Bland-Altman analysis revealed a small mean difference between tests (-9.2 m).

CONCLUSION

The practice of repeating the ISWT appears to be unnecessary for women with morbid obesity, as demonstrated by the excellent reproducibility of the test.

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.

Measurement properties of the incremental shuttle walk test. a systematic review

Background: The incremental shuttle walk test (ISWT) was developed > 20 years ago and has been used to assess peak exercise capacity in a variety of chronic diseases. The aim of this systematic review is to describe the measurement properties of the ISWT in a clinical population.Methods: Of 800 articles identified by electronic and hand searches, 35 were included. Twenty-one articles included data on the validity of the ISWT, 18 on the reliability, four on the responsiveness,and four on the interpretability.Results: Most of the studies were conducted in patients with COPD (n = 13) or cardiac disease(n = 8). For criterion validity, comparisons between distance covered during the ISWT and peak oxygen consumption reported correlations ranging from 0.67 to 0.95 ( P <.01). Intraclass correlation coefficients for test-retest reliability ranged from 0.76 to 0.99. The ISWT was shown to be responsive to pulmonary rehabilitation and bronchodilator administration. The minimal clinically important difference (MCID) in patients with COPD was 48 m. Predictive equations for the distance in the ISWT are available for healthy individuals.Conclusions: The ISWT can be considered a valid and reliable test to assess maximal exercise capacity in individuals with chronic respiratory diseases. The ISWT has been shown to be responsive to pulmonary rehabilitation and bronchodilator use in individuals with COPD, cystic fibrosis,and asthma. Further studies examining responsiveness and the MCID of the ISWT in patients with conditions other than lung diseases are required for the interpretation of interventions in other populations.

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

OBJECTIVE

To determine if the metabolic cost of the incremental shuttle-walking test protocol is the same as treadmill walking or predicted values of walking-speed equations.

SETTING

Primary care (community-based cardiac rehabilitation).

PARTICIPANTS

Eight Caucasian cardiac rehabilitation patients (7 males) with a mean age of 67±5.2 years.

PRIMARY AND SECONDARY OUTCOME MEASURES

Oxygen consumption, metabolic power and energy cost of walking during treadmill and shuttle walking performed in a balanced order with 1 week between trials.

RESULTS

Average overall energy cost per metre was higher during treadmill walking (3.22±0.55 J kg/m) than during shuttle walking (3.00±0.41 J kg/m). There were significant post hoc effects at 0.67 m/s (p<0.004) and 0.84 m/s (p<0.001), where the energy cost of treadmill walking was significantly higher than that of shuttle walking. This pattern was reversed at walking speeds 1.52 m/s (p<0.042) and 1.69 m/s (p<0.007) where shuttle walking had a greater energy cost per metre than treadmill walking. At all walking speeds, the energy cost of shuttle walking was higher than that predicted using the American College of Sports Medicine walking equations.

CONCLUSIONS

The energetic demands of shuttle walking were fundamentally different from those of treadmill walking and should not be directly compared. We warn against estimating the metabolic cost of the incremental shuttle-walking test using the current walking-speed equations.

Reliability of quantitative TUG measures of mobility for use in falls risk assessment

Recent advances in body-worn sensor technology have increased the scope for harnessing quantitative information from the timed-up-and-go test (TUG), well beyond simply the time taken to perform the test. Previous research has shown that the quantitative TUG method can differentiate fallers from non-fallers with greater success than the manually timed TUG or the Berg Balance Test. In order to advance this paradigm of falls risk estimation it is necessary to investigate the robustness of the quantitative TUG variables. This study investigated the inter-session and intra-session reliability of 44 quantitative TUG variables measured from the shanks and lower back of 33 study participants aged between 55-65 yrs. For intra-session reliability, 25 variables demonstrated excellent reliability (ICC>0.75), and 12 demonstrated "fair to good reliability" with ICCs between 0.4 and 0.75. Analysis of test-retest reliability resulted in ICC > 0.75 for 18 out of 44 variables, with 20 variables showing fair to good reliability. Turn time parameters demonstrated poor reliability. We conclude that this is a reliable instrument that may be used as part of a long-term falls risk assessment, with further work required to improve certain turn parameters.

Influence of step length on 6-minute walk test performance in patients with chronic heart failure

OBJECTIVE

To investigate the influence of gait parameters including step length and walking speed during performance of the 6-minute walking test (6MWT) in patients with chronic heart failure (CHF).

DESIGN

Observational study.

SETTING

Specialist heart failure clinic.

PARTICIPANTS

Patients with CHF and aged-matched, apparently healthy controls.

INTERVENTIONS

Each patient and control performed a 6MWT following a standardised protocol in a 15m corridor. The number of steps (defined as step from left foot to right foot) taken every 15m was counted, and reported as minute-by-minute changes in 6MWT performance. In addition, minute-by-minute changes in time taken to complete 15m and mean walking speed throughout the test were calculated.

MAIN OUTCOME MEASURES

Walking speed and step length.

RESULTS

Thirty patients with CHF {87% males; mean age 75 [standard deviation (SD) 8] years} and 10 healthy controls [80% males; mean age 77 (SD 11) years] undertook the 6MWT. For the CHF group, the mean distance walked was 309 (SD 48)m and the peak Borg score was 12 (SD 1). For the controls, the mean distance walked was 334 (SD 138)m and the peak Borg score was 12 (SD 1). Patients with CHF showed no significant minute-by-minute changes in step length or walking speed over the course of the 6MWT. In the first 5minutes, healthy controls had a longer step length and faster walking speed than patients with CHF [step length: mean difference in the first minute was 0.03m, 95% confidence interval (CI) of the difference 0.01 to 0.05m; P=0.02; walking speed: mean difference in the first minute 0.04m/second, 95% CI of the difference 0.02 to 0.07m/second; P=0.01]. A multiple linear regression analysis demonstrated that body mass index (P=0.02) was the most important predictor of 6MWT performance.

CONCLUSION

Patients with CHF have a shorter step length and walk more slowly than controls during the 6MWT. Altered gait mechanics may contribute to limited exercise capacity in patients with CHF.