Estimation of Maximal Oxygen Consumption and Heart Rate Recovery Using the Tecumseh Sub-Maximal Step Test and their Relationship to Cardiovascular Risk Factors

Accuracy of smartwatches for the remote assessment of exercise capacity

Exercise capacity is a strong independent predictor of cardiovascular and all-cause mortality. The utilization of well-established submaximal tests of exercise capacity such as the 6-min walk test (6MWT), 3-min step test (3MST) and 10-chair rise test (10CRT) in the community would improve patient care but requires remote monitoring technology. Consumer grade smartwatches provide such an opportunity, however, their accuracy in measuring physiological responses to these tests is unclear. The aim of this study was to determine the accuracy of consumer grade smartwatches in assessing exercise capacity to develop a framework for remote, unsupervised testing. 16 healthy adults (7 male (44%), age median 27 [interquartile range (IQR) 26,29] years) performed 6MWTs using two protocols: (1) standard-straight 30 m laps (6MWT-standard) and 2) continuous lap-circular 240 m laps around a park (6MWT-continuous lap), 3MSTs and 10CRTs. Each one of these four tests was performed three times across two clinic visits. Each participant was fitted with a Garmin Vivoactive4 and Fitbit Sense smartwatch to measure three parameters: distance, step counts and heart rate (HR) response. Reference measures were a meter-wheel, hand tally counter and ECG, respectively. Mean HR was measured at rest, peak exercise and recovery. Agreement was measured using Bland-Altman analysis for repeated measures and summarized as median absolute percentage errors (MAPE). Distance during 6MWT-continuous lap had better agreement than during 6MWT-standard for both Garmin (MAPE: 6.4% [3.0, 10.4%] versus 20.1% [13.9, 28.4%], p < 0.001) and Fitbit (8.0% [2.9, 10.1% versus 18.8% [15.2, 28.1%], p < 0.001). Garmin measured step count more accurately than Fitbit (MAPE: 1.8% [0.9, 2.9%] versus 8.0% [2.6, 12.3%], p < 0.001). Irrespective of test, both devices showed excellent accuracy in measuring HR at rest and recovery (≤ 3%), while accuracy decreased during peak exercise (Fitbit: ~ 12% and Garmin: ~ 7%). In young adults without mobility difficulties, exercise capacity can be measured remotely using standardized tests and consumer grade smartwatches.

StepTest4all: Improving the Prediction of Cardiovascular Capacity Assessment in Young Adults

Cardiovascular capacity, expressed as maximal oxygen uptake (VO2max), is a strong predictor of health and fitness and is considered a key measure of physiological function in the healthy adult population. The aim of this study was to investigate the influence of the physical activity levels (PAlevel) of participants in the StepTest4all (validated protocol for the estimation of VO2max in adults). The sample consisted of 69 participants, including 27 women (age 21.7 ± 3.6 years; body mass = 63.5 ± 14.8 kg; height = 1.64 ± 0.06 m; body mass index = 23.7 ± 5.3 kg/m2) and 42 men (aged 21.7 ± 3.4 years; body mass = 72.0 ± 7.3 kg; height = 1.77 ± 0.07 m; body mass index = 23.1 ± 2.1 kg/m2). The participants were assigned to one of the two groups: (i) the VO2max prediction group and (ii) the prediction model validation group. In the multiple linear regression, the following predictors of VO2max remained significant: sex (p < 0.001), physical activity level (p = 0.014), and HRR60 (p = 0.020). The prediction equation (R2 = 74.0%, SEE = 4.78) showed a close and strong relationship between the measurements and can be expressed as follows: VO2max = 17.105 + 0.260·(HRR60) + 8.563·(sex) + 4.097·(PAlevel), in which HRR60 is the magnitude of the HR decrease (bpm) in one minute immediately after stopping the step, and sex: men = 1, women = 0, and PAlevel is level 1 (low), level 2 (moderate), and level 3 (high). The StepTest4all was shown to be a suitable method for estimating cardiovascular capacity, expressed as VO2max, in young adults. Retaining PAlevel as a significant predictor allows us to better individualize the participants' VO2max.

Exploring the Relationship Between the Indices of Body Composition With Grip Strength Performance and Peak VO2

Background The importance of measurements of body composition in terms of various indices including Body Mass Index (BMI), Body Surface Area (BSA), Body Size Index (BSI), and Waist to Height ratio (WtHR) in the diagnosis of health risks and mortality outcome analysis has largely been limited to their use relating to determining abdominal obesity. The understanding of the extent of implications of the newer, underutilized indices of body composition is deficient. Peak VO₂ (maximal oxygen uptake) majorly serves for the evaluation of the measure of aerobic capacity. Grip strength performance is a simple, primary, objective predictor of overall physical status and muscular and cardiovascular fitness. This study aimed to derive the relationship between a gamut of parameters such as BMI, BSA, WtHR, BSI, grip strength performance and peak VO₂ investigated using the latest scientific methodology in a cross-section of the population in a rural tertiary care center. Methodology This study was a descriptive, cross-sectional study carried out in a rural medical college in central India. Sixty participants from the healthcare setting were considered eligible for the study within the age group of 18 to 45 years. Anthropometric assessments like height (in cm), weight (in kg), waist circumference (in cm), and BMI were carried out. BSA, WtHR, and BSI were calculated using the respective formulae. VO₂ max (maximal oxygen uptake) recordings were done using the treadmill/ergometer and metabolic module of LabChart software (Bella Vista, New South Wales, Australia). Grip Strength Performance was quantified by measuring the amount of static force with which the hand is able to squeeze a transducer. It was measured using Grip Force Transducer (MLT004 / ST) from AD Instruments (Bella Vista, New South Wales, Australia). Results Upon analysis, a significant negative correlation was obtained between BSI and BMI (r= -0.51, p<0.0001) whereas a significant positive correlation was found between BSA and BMI (r= 0.71, p< 0.0001). A significant correlation was also seen between WtHR and BMI (r= 0.71, p< 0.0001) while a negative significant correlation between peak VO₂ and BMI (r= -024,p=0.0425) was deduced. Similarly, a negative correlation was evident between BSA and BMI (r= -0.46, p=0.0002) with a positive correlation between WtHR and BSA (r= 0.30,p=0.0188). Grip strength performance positively correlated with BSA (r= 0.58, p< 0.0001) whereas peak VO₂ showed a significant negative correlation with WtHR (r= -026,p=0.043). There was also a positive significant correlation between grip strength performance and peak VO₂ (r= 0.37, p=0.0033) Conclusion The study determined the relationships of grip strength performance and peak VO₂, with the body composition indices in order to provide an overview of the mortal risks of an individual which might mediate the prognosis. Based on the relative independence of BSI with peak VO₂ and grip strength performance, the unification of these parameters can help assess the overall health of an individual.

FGF21-Sirtuin 3 Axis Confers the Protective Effects of Exercise Against Diabetic Cardiomyopathy by Governing Mitochondrial Integrity

BACKGROUND

Exercise is an effective nonpharmacological strategy to alleviate diabetic cardiomyopathy (DCM) through poorly defined mechanisms. FGF21 (fibroblast growth factor 21), a peptide hormone with pleiotropic benefits on cardiometabolic homeostasis, has been identified as an exercise responsive factor. This study aims to investigate whether FGF21 signaling mediates the benefits of exercise on DCM, and if so, to elucidate the underlying mechanisms.

METHODS

The global or hepatocyte-specific FGF21 knockout mice, cardiomyocyte-selective β-klotho (the obligatory co-receptor for FGF21) knockout mice, and their wild-type littermates were subjected to high-fat diet feeding and injection of streptozotocin to induce DCM, followed by a 6-week exercise intervention and assessment of cardiac functions. Cardiac mitochondrial structure and function were assessed by electron microscopy, enzymatic assays, and measurements of fatty acid oxidation and ATP production. Human induced pluripotent stem cell-derived cardiomyocytes were used to investigate the receptor and postreceptor signaling pathways conferring the protective effects of FGF21 against toxic lipids-induced mitochondrial dysfunction.

RESULTS

Treadmill exercise markedly induced cardiac expression of β-klotho and significantly attenuated diabetes-induced cardiac dysfunction in wild-type mice, accompanied by reduced mitochondrial damage and increased activities of mitochondrial enzymes in hearts. However, such cardioprotective benefits of exercise were largely abrogated in mice with global or hepatocyte-selective ablation of FGF21, or cardiomyocyte-specific deletion of β-klotho. Mechanistically, exercise enhanced the cardiac actions of FGF21 to induce the expression of the mitochondrial deacetylase SIRT3 by AMPK-evoked phosphorylation of FOXO3, thereby reversing diabetes-induced hyperacetylation and functional impairments of a cluster of mitochondrial enzymes. FGF21 prevented toxic lipids-induced mitochondrial dysfunction and oxidative stress by induction of the AMPK/FOXO3/SIRT3 signaling axis in human induced pluripotent stem cell-derived cardiomyocytes. Adeno-associated virus-mediated restoration of cardiac SIRT3 expression was sufficient to restore the responsiveness of diabetic FGF21 knockout mice to exercise in amelioration of mitochondrial dysfunction and DCM.

CONCLUSIONS

The FGF21-SIRT3 axis mediates the protective effects of exercise against DCM by preserving mitochondrial integrity and represents a potential therapeutic target for DCM.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03240978.

Validation of StepTest4all for Assessing Cardiovascular Capacity in Young Adults

BACKGROUND

Cardiovascular capacity, expressed as maximal oxygen uptake (VO_2max), is a strong predictor of health and fitness and is considered a key measure of physiological function in the healthy adult population. The purpose of this study was to validate a specific step test (StepTest4all) as an adequate procedure to estimate cardiovascular capacity in young adults.

METHODS

The sample was composed of 56 participants, including 19 women (aged 21.05 ± 2.39 years, body mass = 57.50 ± 6.64 kg, height = 1.62 ± 0.05 m, body mass index = 22.00 ± 2.92 kg/m²) and 37 men (aged 22.05 ± 3.14 years, body mass = 72.50 ± 7.73 kg, height = 1.76 ± 0.07 m, body mass index = 23.34 ± 2.17 kg/m²). Participants were included in one of the following groups: (i) the group used to predict the VO_2max, and (ii) the group used to validate the prediction model. All participants performed the StepTest4all protocol. The step height and the intensity of the effort was determined individually. Heart rate and oxygen uptake were measured continuously during rest, effort, and recovery phases. The validation process included the following three stages: (i) mean data comparison, (ii) simple linear regression, and (iii) Bland-Altman analysis.

RESULTS

The linear regression retained, as significant predictors of the VO_2max, sex (p < 0.001) and heart rate recovery for one minute (p = 0.003). The prediction equation revealed a high relationship between measurements (R² = 63.0%, SEE = 5.58). The validation procedure revealed non-significant differences (p > 0.05) between the measured and estimated maximal oxygen uptake, high relationship (R² = 63.3%), and high agreement with Bland-Altman plots. Thus, VO_2max can be estimated with the formula: VO_2max = 22 + 0.3 · (HRR_1min) + 12 · (sex), where HRR_1min is the magnitude of the HR decrease (bpm) in one minute immediately after the step was stopped, and sex: men = 1, women = 0.

CONCLUSIONS

The StepTest4all is an adequate procedure to estimate cardiovascular capacity, expressed as VO_2max, in young adults. In addition, it is possible to determine the qualitative level of cardiovascular capacity from the heart rate recovery for one minute, more specifically, poor: <20, moderate: 20 to 34, good: 35 to 49, and excellent: ≥50. This procedure has the benefit of being simple to apply and can be used by everyone, even at home, without specialist supervision.

Protocol of a mixed-method randomised controlled pilot study evaluating a wilderness programme for adolescent and young adult cancer survivors: the WAYA study

INTRODUCTION

The majority of childhood, adolescent and young adult (AYA) cancer survivors suffer from long-term and late effects such as fatigue, psychological distress or comorbid diseases. Effective health promotion strategies are needed to support the health of this vulnerable group. This protocol provides a methodological description of a study that aims to examine the feasibility and safety of performing a randomised clinical trial (RCT) on a wilderness programme that is developed to support the health of AYA cancer survivors.

METHODS AND ANALYSIS

The pilot RCT study has a mixed-method design, including quantitative and qualitative evaluations. Participants are AYAs, aged 16-39 years, that have been diagnosed with cancer during childhood, adolescence or young adulthood. A total of 40 participants will be randomly assigned to a wilderness programme (n=20) or a holiday programme (n=20). Both arms include participation in an 8-day summer programme, followed by a 4-day programme 3 months later. Primary outcomes are feasibility and safety parameters such as time to recruitment, willingness to be randomised, programme adherence and adverse effects. Secondary outcomes include self-reported health such as self-esteem, quality of life, self-efficacy and lived experiences. Descriptive statistics will be used to analyse outcomes and explore indications of differences between the programmes. Interviews are analysed by directed content analysis and hermeneutic phenomenology. A convergent parallel mixed-method analysis design will be applied to integrate quantitative and qualitative data. Results of this feasibility study will inform the preparation for a larger RCT with AYA cancer survivors.

ETHICS AND DISSEMINATION

The study protocol is approved by the Swedish Ethical Review Authority (reference: 2020-00239). This study will be performed between January 2021 and December 2023. Results will be published in international peer-reviewed journals, presented at conferences and disseminated to participants, cancer societies, healthcare professionals and outdoor instructors.

TRIAL REGISTRATION NUMBER

NCT04761042.

Cardiorespiratory fitness, fatness, and the acute blood pressure response to exercise in adolescence

OBJECTIVE

Exaggerated exercise blood pressure (BP) is associated with cardiovascular risk factors in adolescence. Cardiorespiratory fitness and adiposity (fatness) are independent contributors to cardiovascular risk, but their interrelated associations with exercise BP are unknown. This study aimed to determine the relationships between fitness, fatness, and the acute BP response to exercise in a large birth cohort of adolescents.

METHODS

2292 adolescents from the Avon Longitudinal Study of Parents and Children (aged 17.8 ± 0.4 years, 38.5% male) completed a sub-maximal exercise step test that allowed fitness (VO2 max ) to be determined from workload and heart rate using a validated equation. Exercise BP was measured immediately on test cessation and fatness calculated as the ratio of total fat mass to total body mass measured by DXA.

RESULTS

Post-exercise systolic BP decreased stepwise with tertile of fitness (146 (18); 142 (17); 141 (16) mmHg) but increased with tertile of fatness (138 (15); 142 (16); 149 (18) mmHg). In separate models, fitness and fatness were associated with post-exercise systolic BP adjusted for sex, age, height, smoking, and socioeconomic status (standardized β: -1.80, 95%CI: -2.64, -0.95 mmHg/SD and 4.31, 95%CI: 3.49, 5.13 mmHg/SD). However, when fitness and fatness were included in the same model, only fatness remained associated with exercise BP (4.65, 95%CI: 3.69, 5.61 mmHg/SD).

CONCLUSION

Both fitness and fatness are associated with the acute BP response to exercise in adolescence. The fitness-exercise BP association was not independent of fatness, implying the cardiovascular protective effects of cardiorespiratory fitness may only be realized with more favorable body composition.

Smartphone-Based VO2max Measurement With Heart Snapshot in Clinical and Real-world Settings With a Diverse Population: Validation Study

BACKGROUND

Maximal oxygen consumption (VO₂max) is one of the most predictive biometrics for cardiovascular health and overall mortality. However, VO₂max is rarely measured in large-scale research studies or routine clinical care because of the high cost, participant burden, and requirement for specialized equipment and staff.

OBJECTIVE

To overcome the limitations of clinical VO₂max measurement, we aim to develop a digital VO₂max estimation protocol that can be self-administered remotely using only the sensors within a smartphone. We also aim to validate this measure within a broadly representative population across a spectrum of smartphone devices.

METHODS

Two smartphone-based VO₂max estimation protocols were developed: a 12-minute run test (12-MRT) based on distance measured by GPS and a 3-minute step test (3-MST) based on heart rate recovery measured by a camera. In a 101-person cohort, balanced across age deciles and sex, participants completed a gold standard treadmill-based VO₂max measurement, two silver standard clinical protocols, and the smartphone-based 12-MRT and 3-MST protocols in the clinic and at home. In a separate 120-participant cohort, the video-based heart rate measurement underlying the 3-MST was measured for accuracy in individuals across the spectrum skin tones while using 8 different smartphones ranging in cost from US $99 to US $999.

RESULTS

When compared with gold standard VO₂max testing, Lin concordance was p_c=0.66 for 12-MRT and p_c=0.61 for 3-MST. However, in remote settings, the 12-MRT was significantly less concordant with the gold standard (p_c=0.25) compared with the 3-MST (p_c=0.61), although both had high test-retest reliability (12-MRT intraclass correlation coefficient=0.88; 3-MST intraclass correlation coefficient=0.86). On the basis of the finding that 3-MST concordance was generalizable to remote settings whereas 12-MRT was not, the video-based heart rate measure within the 3-MST was selected for further investigation. Heart rate measurements in any of the combinations of the six Fitzpatrick skin tones and 8 smartphones resulted in a concordance of p_c≥0.81. Performance did not correlate with device cost, with all phones selling under US $200 performing better than p_c>0.92.

CONCLUSIONS

These findings demonstrate the importance of validating mobile health measures in the real world across a diverse cohort and spectrum of hardware. The 3-MST protocol, termed as heart snapshot, measured VO₂max with similar accuracy to supervised in-clinic tests such as the Tecumseh (p_c=0.94) protocol, while also generalizing to remote and unsupervised measurements. Heart snapshot measurements demonstrated fidelity across demographic variation in age and sex, across diverse skin pigmentation, and between various iOS and Android phone configurations. This software is freely available for all validation data and analysis code.

Relationship between blood pressure response during hemodialysis and exercise tolerance or heart rate recovery measured using cardio-pulmonary exercise testing in maintenance hemodialysis patients

Background

This study investigated the association between the blood pressure response during hemodialysis (HD) and exercise tolerance or heart rate recovery (HRR) measured with cardiopulmonary exercise testing (CPX).

Methods

The study enrolled 23 patients who had been undergoing 4-h regular maintenance HD. The maximum workload (Loadpeak), peak oxygen uptake (VO2peak), workload and oxygen uptake at the anaerobic threshold (LoadAT and VO2AT, respectively), and HRR were measured with CPX. The average systolic blood pressure during HD (SBPav) was measured, and the number of times the SBP was less than 100 mmHg was determined in the 2-week period after CPX.

Results

The SBPav showed a significant correlation with LoadAT (r = 0.46) and Loadpeak (r = 0.43, p < 0.05). The number of times the SBP was less than 100 mmHg showed a significant correlation with the HRR (r = − 0.44, p < 0.05).

Conclusion

Exercise intolerance and HRR in HD patients may be associated with blood pressure instability during HD.

Cardiorespiratory Fitness as a Correlate of Cardiovascular, Anthropometric, and Physical Risk Factors: Using the Ruffier Test as a Template

Background

Assessment of cardiorespiratory fitness (CRF) is a standard procedure in routine clinical practices. Early identification of risk factors through screening is vital in the fight against chronic diseases. Evaluation of CRF can impose cost implications in the clinical setting; thus, a simple and easy-to-use test is to be advocated. The Ruffier test is a simple test that can assess CRF, and it is necessary to find whether the test reflects the effects of compounding factors in CRF.

Objective

This study aims to determine the association between CRF (estimated VO2max) with cardiovascular, anthropometric, and physical risk factors using the Ruffier test.

Methods

A cross-sectional study with a sample of 52 male participants was conducted. Before the Ruffier test, each participant's body weight, height, waist circumference, skinfold thickness, thigh length, lower-limb length, thigh circumference, physical activity, blood pressure, smoking, diabetes, and pulmonary functions were recorded, and these factors correlated with CRF.

Results

There was a significant inverse relationship found between the estimated VO2max and age, height, body weight, body mass index, waist circumference, a sum of skinfold, fat percentage, thigh length, lower-limb length, thigh circumference, smoking, blood pressure, heart rates, and diabetes (p < 0.05). A significant positive correlation was found between the estimated VO2max with physical activity and respiratory functions (p < 0.05). In the multivariable model, body weight and resting heart rate were significantly inversely associated with the estimated VO2max(p < 0.05).

Conclusion

Using the Ruffier test, various risk factors of CRF are correlated with the estimated VO2max. This test reflects the effects of different compounding factors on CRF; therefore, it can be used in routine clinical practices to identify the risk factors early.

Submaximal Exercise Testing in Cardiovascular Rehabilitation Settings (BEST Study)

Background

This study compared changes in measured versus predicted peak aerobic power (V̇O_2peak) following cardiovascular rehabilitation (CR). Peak cardiopulmonary exercise testing (CPET) results were compared to four V̇O_2peak estimation methods: the submaximal modified Bruce treadmill, Astrand-Ryhming cycle ergometer, and Chester step tests, and the Duke Activity Status Index (DASI).

Methods

Adults with cardiovascular disease (CVD) who completed a 12-week CR program were assessed at baseline and 12 weeks follow-up. CPET, the DASI and three subsequent submaximal exercise tests were performed in a random order.

Results

Of the 50 adults (age: 57 ± 11 years) who participated, 46 completed the 12-week CR program and exercise tests. At baseline 69, 68, and 38% of the treadmill, step and cycle tests were successfully completed, respectively. At follow-up 67, 80, and 46% of the treadmill, step and cycle tests were successfully completed, respectively. No severe adverse events occurred. Significant improvements in V̇O_2peak were observed with CPET (3.6 ± 5.5 mL^.kg^–1.min^–1, p < 0.001) and the DASI (2.3 ± 4.2 mL^.kg^–1.min^–1, p < 0.001). Bland-Altman plots of the change in V̇O_2peak between CPET and the four V̇O_2peak estimation methods revealed the following: a proportional bias and heteroscedastic 95% limits of agreement (95% LoA) for the treadmill test, and for the cycle and step tests and DASI, mean bias’ and 95% LoA of 1.0 mL^.kg^–1.min^–1 (21.3, −19.3), 1.4 mL^.kg^–1.min^–1 (15.0, −12.3) and 1.0 mL^.kg^–1.min^–1 (13.8, −11.8), respectively.

Conclusion

Given the greater number of successful tests, no serious adverse events and acceptable mean bias, the step test appears to be a valid and safe method for assessing group-level mean changes in V̇O_2peak among patients in CR. The DASI also appears to be a valid and practical questionnaire. Wide limits of agreement, however, limit their use to predict individual-level changes.

Validation of Submaximal Step Tests and the 6-Min Walk Test for Predicting Maximal Oxygen Consumption in Young and Healthy Participants

Background: This study aimed to test the validity of three different submaximal tests (i.e., 3-min step test with 20.3-cm step box height (3MST₂₀), 3-min step test with 30-cm step box height (3MST₃₀), and 6-min walk test (6MWT)) in estimating maximal oxygen consumption (VO_2max) in young and healthy individuals. Methods: The 3MST₂₀, 3MST₃₀, 6MWT, as well as the cardiopulmonary exercise test (CPET) were performed in 73 participants (37 men and 36 women; mean age: 30.8 ± 9.3 years). All participants visited the clinic three times in a random order for anthropometric measurements, three submaximal tests, and the VO_2max test. Multiple linear regression analyses were conducted to construct the VO_2max prediction equations for each submaximal test. Results: The prediction equations developed based on multiple regression analyses for each submaximal tests were as follows: 3MST₂₀: VO_2max = 86.0 − 10.9 × sex (male = 1, female = 2) − 0.4 × age − 0.1 × weight − 0.1 × heart rate recovery at 30 s (HRR30s); 3MST₃₀: VO_2max = 84.5 − 10.2 × sex (male = 1, female = 2) − 0.4 × age − 0.1 × weight − 0.1 × HRR30s; and 6MWT: VO_2max = 61.1 − 11.1 × sex (male = 1, female = 2) − 0.4 × age − 0.2 × weight − 0.2 × (distance walked·10⁻¹). The estimated VO_2max values based on formulated equations were 37.0 ± 7.9, 37.3 ± 7.6, and 36.9 ± 7.9 mL∙kg⁻¹∙min⁻¹ derived from the 3MST₂₀, 3MST₃₀, and 6MWT, respectively. These estimated VO_2max values were not significantly different from the measured VO_2max value, 37.3 mL∙kg⁻¹∙min⁻¹. The estimated VO_2max based on the 3MST₂₀, 3MST₃₀, and 6MWT results explained 73.4%, 72.2%, and 74.4% of the variances in the measured VO_2max (p < 0.001), respectively. Conclusions: The 3MST₂₀, 3MST₃₀, and 6MWT were valid in estimating VO_2max in relatively young and healthy Asian individuals.

Yoga and Cardiovascular Health Trial (YACHT): a UK-based randomised mechanistic study of a yoga intervention plus usual care versus usual care alone following an acute coronary event

OBJECTIVE

To determine the effects of yoga practice on subclinical cardiovascular measures, risk factors and neuro-endocrine pathways in patients undergoing cardiac rehabilitation (CR) following acute coronary events.

DESIGN

3-month, two-arm (yoga +usual care vs usual care alone) parallel randomised mechanistic study.

SETTING

One general hospital and two primary care CR centres in London. Assessments were conducted at Imperial College London.

PARTICIPANTS

80 participants, aged 35-80 years (68% men, 60% South Asian) referred to CR programmes 2012-2014.

INTERVENTION

A certified yoga teacher conducted yoga classes which included exercises in stretching, breathing, healing imagery and deep relaxation. It was pre-specified that at least 18 yoga classes were attended for inclusion in analysis. Participants and partners in both groups were invited to attend weekly a 6- to 12-week local standard UK National Health Service CR programme.

MAIN OUTCOME MEASURES

(i) Estimated left ventricular filling pressure (E/e'), (ii) distance walked, fatigue and breathlessness in a 6 min walk test, (iii) blood pressure, heart rate and estimated peak VO2 following a 3 min step-test. Effects on the hypothalamus-pituitary-adrenal axis, autonomic function, body fat, blood lipids and glucose, stress and general health were also explored.

RESULTS

25 participants in the yoga + usual care group and 35 participants in the usual care group completed the study. Following the 3-month intervention period, E/e' was not improved by yoga (E/e': between-group difference: yoga minus usual care:-0.40 (-1.38, 0.58). Exercise testing and secondary outcomes also showed no benefits of yoga.

CONCLUSIONS

In this small UK-based randomised mechanistic study, with 60 completing participants (of whom 25 were in the yoga + usual care group), we found no discernible improvement associated with the addition of a structured 3-month yoga intervention to usual CR care in key cardiovascular and neuroendocrine measures shown to be responsive to yoga in previous mechanistic studies.

TRIAL REGISTRATION NUMBER

NCT01597960; Pre-results.

Masked hypertension and submaximal exercise blood pressure among adolescents from the Avon Longitudinal Study of Parents and Children (ALSPAC)

PURPOSE

Masked hypertension is associated with increased cardiovascular risk but is undetectable by clinic blood pressure (BP). Elevated systolic BP responses to submaximal exercise reveal the presence of masked hypertension in adults, but it is unknown whether this is the case during adolescence. We aimed to determine if exercise BP was raised in adolescents with masked hypertension, and its association with cardiovascular risk markers.

METHODS

A total of 657 adolescents (aged 17.7 ± 0.3 years; 41.9% male) from the Avon longitudinal study of parents and children (ALSPAC) completed a step-exercise test with pre-, post-, and recovery-exercise BP, clinic BP and 24-hour ambulatory BP. Masked hypertension was defined as clinic BP <140/90 mm Hg and 24-hour ambulatory BP ≥130/80 mm Hg. Assessment of left-ventricular (LV) mass index and carotid-femoral pulse wave velocity (aortic PWV) was also undertaken. Thresholds of clinic, pre-, post-, and recovery-exercise systolic BP were explored from ROC analysis to identify masked hypertension.

RESULTS

Fifty participants (7.8%) were classified with masked hypertension. Clinic, pre-, post-, and recovery-exercise systolic BP were associated with masked hypertension (AUC ≥ 0.69 for all, respectively), with the clinic systolic BP threshold of 115 mm Hg having high sensitivity and specificity and exercise BP thresholds of 126, 150, and 130 mm Hg, respectively, having high specificity and negative predictive value (individually or when combined) for ruling out the presence of masked hypertension. Additionally, this exercise systolic BP above the thresholds was associated with greater left-ventricular mass index and aortic PWV.

CONCLUSIONS

Submaximal exercise systolic BP is associated with masked hypertension and adverse cardiovascular structure in adolescents. Exercise BP may be useful in addition to clinic BP for screening of high BP and cardiovascular risk in adolescents.

The Reliability and Validity of a Modified Squat Test to Predict Cardiopulmonary Fitness in Healthy Older Men

Background

Shortcomings are noted in currently available cardiopulmonary field tests for the older adult and thus relevant research is still ongoing.

Purpose

The purpose of this study was to investigate the reliability and validity of a modified squat test and to establish a regression model for predicting aerobic fitness in the older adult.

Methods

Twenty-five healthy men aged 60 to 75 years completed this study. Each subject performed two modified squat tests with a prototype testing equipment and a maximal exercise test to determine maximal oxygen consumption. Recovery heart rates (HR) (0~30, 60~90, and 120~150 seconds) were measured following the modified squat tests. The fitness indexes included the sum of recovery HR, recovery HR index, age-adjusted recovery HR index, and immediate HR.

Results

The results revealed that the age-adjusted recovery HR index fitness had the highest intraclass correlation coefficients (ICC) of 0.9 and Pearson's correlation coefficients of 0.71, which suggested the modified squat test can reasonably assess cardiopulmonary fitness for the older adult. The regression equation for estimating aerobic power was [Formula: see text] = 16.781 + 16.732 × (age-adjusted recovery HR index) + 0.02467 × (physical activity level).

Conclusion

The modified squat test is a valid and reliable field test and thus can be an option to assess the cardiopulmonary fitness level of healthy older men in clinics or communities.

Relationship between hand grip strength and peak VO2 in community-dwelling elderly outpatients

Background: Hand grip strength and peak oxygen uptake (VO2) are important components of frailty. However, the relationship between these two variables among community-dwelling elderly people is still unclear. The present study aimed to investigate this relationship.Methods: Participants were 190 Japanese community-dwelling elderly outpatients (61 men and 129 women, mean age 78.0 years). Hand grip strength of participants’ dominant hand was measured using a Smedley-type hand dynamometer. Peak VO2 levels were assessed with a cardiopulmonary exercise test. Skeletal muscle mass index (SMI) and usual walking speed were assessed physiologically and physically. Sample size was calculated using G*Power 3.1.9.2.Results: There were significant correlations between hand grip strength and age (r = −0.22), peak VO2 (r = 0.40), SMI (r = 0.51), and usual walking speed (r = 0.29). There were significant differences in age, peak VO2 and SMI after participants were divided into normal and low hand grip strength groups according to the Asian Working Group for Sarcopenia threshold, whether both sexes were combined or considered separately. Multiple logistic regression analysis showed that peak VO2, SMI and age were independent determinants of hand grip strength after adjusting for potential confounders (Exp(B) = 0.871; 0.475; 1.065). Longitudinal analysis after 6 months of exercise training showed the percentage of change in hand grip strength and peak VO2 were correlated positively (r = 0.22) for 92 participants. Conclusion: Peak VO2 is independently associated with hand grip strength among community-dwelling elderly outpatients.