A simple step test to estimate cardio-respiratory fitness levels of rheumatoid arthritis patients in a clinical setting

Association Between Change in Nonexercise Estimated Cardiorespiratory Fitness and Mortality in Men

Objective

To examine the association between change in nonexercise estimated cardiorespiratory fitness (eCRF) and mortality risk in adult men.

Patients and Methods

A total of 10,445 men (mean age, 44.6±9.3 years) from the Aerobics Center Longitudinal Study underwent 2 comprehensive medical examinations and peak work rate tests between January 1, 1979, and December 31, 2002, with an average time between measures of 5.7±4.9 years. Participants were observed for 11.6±6.4 years after their second examination until death or December 31, 2003. The eCRF was calculated with the Jackson et al (2012) and Nes et al (2011) published nonexercise estimation equations. Cox proportional hazards models were performed to examine the association between change in eCRF and all-cause and cardiovascular disease (CVD) mortality.

Results

There were 601 deaths (192 CVD deaths) during the follow-up period. For both eCRF equations, a higher eCRF at baseline was associated with significant reductions in mortality risk from all causes and CVD (P<.001). Change in eCRF by the Jackson equation remained significantly associated with all-cause mortality (P<.001) and CVD mortality (P=.02) after multivariable adjustment. Every 1 metabolic equivalent (3.5 mL·kg⁻¹·min⁻¹) increase in eCRF was associated with a 21% and 22% reduction in mortality risk from all causes or CVD, respectively. No significant associations were observed between change in eCRF by the Nes equation and all-cause (P=.69) or CVD (P=.85) mortality risk after multivariable adjustment.

Conclusion

The association between change in nonexercise eCRF and mortality risk may be equation dependent.

Personalized Lifestyle Intervention and Functional Evaluation Health Outcomes SurvEy: Presentation of the LIFEHOUSE Study Using N-of-One Tent-Umbrella-Bucket Design

The working definition of health is often the simple absence of diagnosed disease. This common standard is limiting given that changes in functional health status represent early warning signs of impending health declines. Longitudinal assessment of functional health status may foster prevention of disease occurrence and modify disease progression. The LIFEHOUSE (Lifestyle Intervention and Functional Evaluation-Health Outcomes SurvEy) longitudinal research project explores the impact of personalized lifestyle medicine approaches on functional health determinants. Utilizing an adaptive tent-umbrella-bucket design, the LIFEHOUSE study follows the functional health outcomes of adult participants recruited from a self-insured employee population. Participants were each allocated to the tent of an all-inclusive N-of-one case series. After assessing medical history, nutritional physical exam, baseline functional status (utilizing validated tools to measure metabolic, physical, cognitive, emotional and behavioral functional capacity), serum biomarkers, and genomic and microbiome markers, participants were assigned to applicable umbrellas and buckets. Personalized health programs were developed and implemented using systems biology formalism and functional medicine clinical approaches. The comprehensive database (currently 369 analyzable participants) will yield novel interdisciplinary big-health data and facilitate topological analyses focusing on the interactome among each participant's genomics, microbiome, diet, lifestyle and environment.

Test-Retest Reliability of Home-Based Fitness Assessments Using a Mobile App (R Plus Health) in Healthy Adults: Prospective Quantitative Study

BACKGROUND

Poor physical fitness has a negative impact on overall health status. An increasing number of health-related mobile apps have emerged to reduce the burden of medical care and the inconvenience of long-distance travel. However, few studies have been conducted on home-based fitness tests using apps. Insufficient monitoring of physiological signals during fitness assessments have been noted. Therefore, we developed R Plus Health, a digital health app that incorporates all the components of a fitness assessment with concomitant physiological signal monitoring.

OBJECTIVE

The aim of this study is to investigate the test-retest reliability of home-based fitness assessments using the R Plus Health app in healthy adults.

METHODS

A total of 31 healthy young adults self-executed 2 fitness assessments using the R Plus Health app, with a 2- to 3-day interval between assessments. The fitness assessments included cardiorespiratory endurance, strength, flexibility, mobility, and balance tests. The intraclass correlation coefficient was computed as a measure of the relative reliability of the fitness assessments and determined their consistency. The SE of measurement, smallest real difference at a 90% CI, and Bland-Altman analyses were used to assess agreement, sensitivity to real change, and systematic bias detection, respectively.

RESULTS

The relative reliability of the fitness assessments using R Plus Health was moderate to good (intraclass correlation coefficient 0.8-0.99 for raw scores, 0.69-0.99 for converted scores). The SE of measurement and smallest real difference at a 90% CI were 1.44-6.91 and 3.36-16.11, respectively, in all fitness assessments. The 95% CI of the mean difference indicated no significant systematic error between the assessments for the strength and balance tests. The Bland-Altman analyses revealed no significant systematic bias between the assessments for all tests, with a few outliers. The Bland-Altman plots illustrated narrow limits of agreement for upper extremity strength, abdominal strength, and right leg stance tests, indicating good agreement between the 2 assessments.

CONCLUSIONS

Home-based fitness assessments using the R Plus Health app were reliable and feasible in young, healthy adults. The results of the fitness assessments can offer a comprehensive understanding of general health status and help prescribe safe and suitable exercise training regimens. In future work, the app will be tested in different populations (eg, patients with chronic diseases or users with poor fitness), and the results will be compared with clinical test results.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2000030905; http://www.chictr.org.cn/showproj.aspx?proj=50229.

Development and Validation of 3 Min Incremental Step-In-Place Test for Predicting Maximal Oxygen Uptake in Home Settings: A Submaximal Exercise Study to Assess Cardiorespiratory Fitness

The purpose of this research was to develop the 3 min incremental step-in-place (3MISP) test for predicting maximal oxygen uptake (V.O_2max). A total of 205 adults (20–64 years) completed the 3MISP and V.O_2max tests. Using age, gender, body composition (BC) including percent body fat (PBF) or body mass index (BMI), and with or without heart rate (HR) at the beginning of exercise (HR0) or difference between HR at the third minute during the exercise and the first minute post exercise (ΔHR3 − HR4) in the 3MISP test, six V.O_2max prediction models were derived from multiple linear regression. Age (r = −0.239), gender (r = 0.430), BMI (r = −0.191), PBF (r = −0.706), HR0 (r = −0.516), and ΔHR3 − HR4 (r = 0.563) were significantly correlated to V.O_2max. Among the six V.O_2max prediction models, the PBF model^{∆HR3 − HR4} has the highest accuracy. The simplest models with age, gender, and PBF/BMI explained 54.5% of the V.O_2max in the PBF model^BC and 39.8% of that in the BMI model^BC. The addition of HR0 and ∆HR3 − HR4 increases the variance of V.O_2max explained by the PBF and BMI models^{∆HR3 − HR4} by 17.98% and 45.23%, respectively, while standard errors of estimate decrease by 10.73% and 15.61%. These data demonstrate that the models established using 3MISP-HR data can enhance the accuracy of V.O_2max prediction.

Testing of a Self-administered 6-Minute Walk Test Using Technology: Usability, Reliability and Validity Study

BACKGROUND

The need to attend a medically supervised hospital- or clinic-based appointment is a well-recognized barrier to exercise participation. The development of reliable and accurate home-based functional tests has the potential to decrease the burden on the health care system while enabling support, information, and assessment.

OBJECTIVE

This study aims to explore the usability (ie, acceptability, satisfaction, accuracy, and practicality) of the EasyMeasure app to self-administer the 6-minute walk test (6MWT) in young, healthy adults and determine parallel form reliability and construct validity of conducting a self-administered 6MWT using technology.

METHODS

We used a usability study design. English-speaking, undergraduate university students who had access to an iPhone or iPad device running iOS 10 or later and self-reported ability to walk for 6 minutes were recruited for this study. Consenting participants were randomized to either a standard 6MWT group (ie, supervised without the use of the app) or a technology 6MWT group (ie, unsupervised with the app to mimic independent implementation of the test). All participants performed a maximal treadmill test. Participants in the 6MWT group completed the Unified Theory of Acceptance and Use of Technology (UTAUT) questionnaire and a satisfaction questionnaire after completing the assessment. Parallel form reliability of the 6MWT using technology was analyzed by comparing participant self-administered scores and assessor scores using Pearson correlation coefficients across and between trials. Construct validity was assessed by comparing participant 6MWT scores (both standard and using technology) with maximum treadmill test variables (peak oxygen uptake and ventilatory threshold [VT]).

RESULTS

In total, 20 university students consented to participate in the study. All but 2 participants (8/10, 80%) in the technology 6MWT group had deviations that prevented them from accurately conducting the 6MWT using the app, and none of the participants were able to successfully score the 6MWT. However, a significantly strong correlation was found (r=.834; P=.003) when comparing participants' scores for the 6MWT using technology with the assessors' scores. No significant correlations were found between maximal treadmill test peak oxygen uptake scores and 6MWT prediction equations using standard 6MWT scores (equation 1: r=0.119; P=.78; equation 2: r=0.095; P=.82; equation 3: r=0.119; P=.78); however, standard 6MWT scores were significantly correlated with VT values (r=0.810; P=.02). The calculated submaximal treadmill scores and assessor 6MWT scores using technology also demonstrated a significant correlation (r=0.661; P=.04).

CONCLUSIONS

This study demonstrated significant usability concerns regarding the accuracy of a self-administered 6MWT using the EasyMeasure app. However, the strong and significant correlation between the 6MWT and VT values demonstrates the potential of the 6MWT to measure functional capacity for community-based exercise screening and patient monitoring.

Testes funcionais validados em indivíduos hospitalizados e não hospitalizados: revisão sistemática

Objetivo: Realizar uma revisão sistemática sobre os testes funcionais validados em diferentes perfis de indivíduos hospitalizados e não hospitalizados e avaliar as evidências psicométricas para confiabilidade e validade. Métodos: Trata-se de uma revisão sistemática. Foram utilizadas as bases de dados EMBASE, MEDLINE, Lilacs e SciELO com as palavras-chave Functional Tests (Walk Test, Gait Speed Test, Chair Stand Test, Timed Up And Go, Step Test),Validation Studies as Topic e sinônimos. Foram incluídos estudos de validação de testes funcionais em indivíduos hospitalizados ou não hospitalizados que utilizaram os critérios de validade e/ou confiabilidade e relacionaram os testes a diferentes variáveis. Esses artigos poderiam ser observacionais longitudinais ou de corte transversal ou estudos de validação que utilizaram dados de ensaios clínicos. Foram excluídos os artigos que não apresentaram características importantes da amostra e a descrição do teste. Resultados: A pesquisa resultou em 36.150 artigos, e 89 foram incluídos. Os estudos foram organizados em tabelas com informações como autor, ano; critérios de validação; amostra; teste; variáveis associadas; resultados. A qualidade dos artigos foi avaliada por meio da Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Conclusão: Os testes funcionais são válidos e confiáveis para a avaliação de indivíduos hospitalizados e não hospitalizados, estando associados à força muscular, capacidade de caminhar, controle postural, atividades de vida diária, risco de quedas, hospitalização e mortalidade.

Promotion of Healthy Aging Within a Community Center Through Behavior Change: Health and Fitness Findings From the AgeWell Pilot Randomized Controlled Trial

The purpose of this randomized controlled trial was to determine if behavior change through individual goal setting (GS) could promote healthy aging, including health and fitness benefits in older adults who attended a community "AgeWell" Center for 12 months. Seventy-five older adults were randomly allocated to either a control or a GS group. Health outcomes were measured at baseline and after 12 months of the participants' having access to the exception of Agewell Center facilities. The findings demonstrate that participation in the Center in itself was beneficial, with improved body composition and reduced cardiovascular risk in both groups (p < .05), and that this kind of community-based resource offers valuable potential for promoting protective behaviors and reducing health risk. However, a specific focus on identifying individual behavior change goals was required in order to achieve increased activity engagement (p < .05) and to bring about more substantial improvements in a range of health, diet, and physical function measures (p < .05).

Assessment of the Effects of Aerobic Fitness on Cerebrovascular Function in Young Adults Using Multiple Inversion Time Arterial Spin Labeling MRI

This cross-sectional study investigated the effects of aerobic fitness on cerebrovascular function in the healthy brain. Gray matter cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) were quantified in a sample of young adults within a normal fitness range. Based on existing Transcranial Doppler ultrasound and fMRI evidence, we predicted a positive relationship between fitness and resting gray matter CBF and CVR. Exploratory hypotheses that higher V . O2peak would be associated with higher GM volume and cognitive performance were also investigated. 20 adults underwent a V . O2peak test and a battery of cognitive tests. All subjects also underwent an MRI scan where multiple inversion time (MTI) pulsed arterial spin labeling (PASL) was used to quantify resting CBF and CVR to 5% CO2. Region of interest analysis showed a non-significant inverse correlation between whole-brain gray matter CBF and V . O2peak; r = -0.4, p = 0.08, corrected p (p') = 0.16 and a significant positive correlation between V . O2peak and whole-brain averaged gray matter CVR; r = 0.62, p = 0.003, p' = 0.006. Voxel-wise analysis revealed a significant inverse association between V . O2peak and resting CBF in the left and right thalamus, brainstem, right lateral occipital cortex, left intra-calcarine cortex and cerebellum. The results of this study suggest that aerobic fitness is associated with lower baseline CBF and greater CVR in young adults.

The impact of cardiorespiratory fitness on classical cardiovascular disease risk factors in rheumatoid arthritis: a cross-sectional and longitudinal study

Rheumatoid arthritis (RA) is associated with an increased risk of cardiovascular disease (CVD). Advanced measures of cardiorespiratory fitness (CRF) are associated with CVD risk factors. The present study aimed to examine whether CVD risk factors can predict clinic-based measures of CRF, using the Siconolfi step test and to determine if exercise can improve RA patients' cardiovascular health. Sixty-five RA patients (46 females, age 58 ± 11 years) completed assessments of CRF, CVD risk factors, body composition and RA characteristics. Ten patients participated in a follow-up 8-week exercise intervention. CRF was low (22 ml kg^-1 min^-1) and associated with higher diastolic blood pressure (r = - 0.37, p = 0.002), higher global CVD risk (r = - 0.267,  p = 0.031) and worse body composition profile (body fat, r = - 0.48, p < 0.001; waist, r = - 0.65, p < 0.001; hip, r = - 0.58, p < 0.001). Regular exercise significantly improved CRF (p = 0.021), lower body strength (p < 0.001), agility (p < 0.001), systolic blood pressure (p = 0.021), body fat (p = 0.018), waist circumference (p = 0.035), hip circumference (p = 0.016), disease activity (p = 0.002), disability (p = 0.007) and QoL (p = 0.004). Elevated diastolic blood pressure and worse body composition profile are strong predictors of clinic-based measures of CRF. CRF is an important determinant of CVD risk and warrants inclusion in the routine assessment of RA patients. Regular exercise can improve CRF and CVD risk factors without any exacerbation of disease activity and should be offered as part of routine care.

Developing and Validating a Step Test of Aerobic Fitness among Elementary School Children

Purpose: The tests to estimate aerobic fitness among children require substantial space and maximum effort, which is often difficult for children. We developed a simple submaximal step test (Step Test of Endurance for Pediatrics, or STEP) and assessed its reliability, validity, and ability to estimate aerobic fitness among elementary school children. Method: Children aged 5-10 years completed the STEP with a protocol consisting of 0.1-, 0.2-, and 0.3-metre (4, 8, and 12 in.) step heights. Participants underwent treadmill testing with open circuit spirometry to determine actual maximal oxygen consumption (V̇o_2max). Intra-class correlation coefficients (ICCs) assessed test-retest reliability of the STEP and its component tests. Multivariate linear regression assessed the associations between the STEP and V̇o_2max, adjusting for potential covariates such as age, sex, BMI, and comorbidity count. Results: The STEP showed excellent reliability (ICC ≥ 0.92; N = 170), irrespective of effort level during testing. Significant effort issues and collinearity among the independent variables led us to exclude children aged 5-6 years (n = 45) from the regression analysis. The final regression model for children aged 7-10 years with adequate effort (n = 111), as defined by a respiratory exchange ratio of 1.0 or more, showed that the STEP, sex, and BMI were significantly predictive of V̇o_2max (R ² = 0.51). Conclusions: This new, effort-independent step test can estimate the aerobic fitness of children aged 7-10 years. Regression equations to estimate V̇o_2max from the STEP were provided.

The Siconolfi step test: a valid and reliable assessment of cardiopulmonary fitness in older men with prostate cancer

BACKGROUND

Assessing fitness and promoting regular physical activity can improve health outcomes and early recovery in prostate cancer. This is however, underutilised in clinical practice. The cardiopulmonary exercise test (CPET) is increasingly being used pre-treatment to measure aerobic capacity and peak oxygen consumption (VO2peak - a gold standard in cardiopulmonary fitness assessment). However, CPET requires expensive equipment and may not always be appropriate. The Siconolfi step test (SST) is simpler and cheaper, and could provide an alternative.The aim of this study was to evaluate the validity and reliability of SST for predicting cardiopulmonary fitness in men with prostate cancer. Men were recruited to this two-centre study (Surrey and Newcastle, United Kingdom) after treatment for locally advanced prostate cancer. They had one or more of three risk factors: elevated blood pressure, overweight (BMI > 25), or androgen deprivation therapy (ADT). Cardiopulmonary fitness was measured using SST and cycle ergometry CPET, at two visits three months apart. The validity of SST was assessed by comparing it to CPET. The VO2peak predicted from SST was compared to the VO2peak directly measured with CPET. The reliability of SST was assessed by comparing repeated measures. Bland-Altman analysis was used to derive limits of agreement in validity and reliability analysis.

RESULTS

Sixty-six men provided data for both SST and CPET. These data were used for validity analysis. 56 men provided SST data on both visits. These data were used for reliability analysis. SST provided valid prediction of the cardiopulmonary fitness in men > 60 years old. The average difference between CPET and SST was 0.64 ml/kg/min with non-significant positive bias towards CPET (P = 0.217). Bland-Altman 95% limits of agreement of SST with CPET were ± 7.62 ml/kg/min. SST was reliable across the whole age range. Predicted VO2peak was on average 0.53 ml/kg/min higher at Visit 2 than at Visit 1 (P = 0.181). Bland-Altman 95% limits of agreement between repeated SST measures were ± 5.84 ml/kg/min.

CONCLUSIONS

SST provides a valid and reliable alternative to CPET for the assessment of cardiopulmonary fitness in older men with prostate cancer. Caution is advised when assessing men 60 years old or younger because the VO2peak predicted with SST was significantly lower than that measured with CPET.

Perceived Versus Performance Fatigability in Patients With Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, inflammatory disease that affects 1% of the general population. Fatigue is a common complaint of patients with RA, however their perceived fatigue may be more exacerbated than objective measures of fatigue may indicate. The assessment of fatigue is made complex due to inconsistent and vague terms used to define fatigue, and the task dependence of fatigability. Fatigue is defined as a state of exhaustion and decreased strength, while fatigability indicates an individual's susceptibility to fatigue. In order to offer some clarity to the manifestation of fatigue in clinical populations, in this review we outline that fatigue should be described with subsections that are related to the symptom, such as: perceived fatigability and performance fatigability. Where perceived fatigability indicates the subjective state of the individual and thus involves the individual's subjective measure of fatigue, performance fatigability would be measured through clinical and laboratory-based assessments that quantify the functional decline in performance. This review describes RA and the various neuromuscular changes associated with the disease that can lead to alterations in both perceived and performance fatigue. From there, we discuss fatigue and RA, how fatigue can be assessed, effects of exercise interventions on RA symptoms and fatigue, and recommendations for future studies investigating subjective and objective measures of fatigability.

Change in Submaximal Cardiorespiratory Fitness and All-Cause Mortality

OBJECTIVE

To evaluate the relationship between change in submaximal cardiorespiratory fitness (sCRF) and all-cause mortality risk in adult men and women.

PATIENTS AND METHODS

A prospective study with at least 2 clinical visits (mean follow-up time, 4.2±3.0 years) between April 1974 and January 2002 was conducted to assess the relationship between change in sCRF and mortality risk during follow-up. Participants were 6106 men and women. Submaximal CRF was determined using the heart rate obtained at the 5-minute mark of a graded maximal treadmill test used to determine maximal CRF (mCRF). Change in sCRF from baseline to follow-up was categorized into 3 groups: increased fitness (decreased heart rate, <-4.0 beats/min), stable fitness (heart rate, -4.0 to 3.0 beats/min), and decreased fitness (increased heart rate, >3.0 beats/min).

RESULTS

The mean change in sCRF at follow-up for all 6106 study participants was -0.5±10.0 beats/min, and the mean change in mCRF was -0.3±1.4 metabolic equivalents. Change in sCRF was related to change in mCRF, though the variance explained was small (R²=0.21; P<.001). The hazard ratios (95% CIs) for all-cause mortality were 0.60 (0.38-0.96) for stable and 0.59 (0.35-1.00) for increased sCRF compared with decreased sCRF after adjusting for age, change in weight, and other common risk factors for premature mortality. The hazard ratios for changes in sCRF and mCRF were not significant after adjusting for changes in mCRF (P=.29) and sCRF (P=.60), respectively.

CONCLUSION

A simple 5-minute submaximal test of CRF identified that adults who maintained or improved sCRF were less likely to die from all causes during follow-up than were adults whose sCRF decreased.

The 8-foot up and go test is the best way to assess physical function in the rheumatoid arthritis clinic

Objectives

RA is characterized by poor physical function, which compromises patients’ quality of life and outcome. Clinical assessment of function is usually performed using self-reported questionnaires, such as the Multi-Dimensional HAQ (MDHAQ) and the Short Form-36 (physical component) (SF36-PC). However, such subjective measures may not accurately reflect real functional status. This study aimed to determine: (i) which clinically practicable objective test best represents overall physical function; and (ii) the extent to which self-reported subjective functional measures reflect objectively assessed function.

Methods

Objective [isometric knee extensor strength, handgrip strength, sit-to-stands in 30 s, 8-foot up and go (8′UG), 50-foot walk (50′W) and estimated aerobic capacity (V̇O₂max)] and subjective (MDHAQ and SF36-PC) measures of function were correlated with one another to determine the best overall test of functional status in 82 well-controlled RA patients (DAS28 (s.d.) = 2.8 (1.0)).

Results

In rank order of size, averaged correlations (r) to the other outcome measures were as follows: 8′UG: 0.650; 50′W: 0.636; isometric knee extensor strength: 0.502; handgrip strength: 0.449; sit-to-stands in 30 s: 0.432; and estimated V̇O₂max: 0.358. The MDHAQ was weakly (0.361) and the SF36-PC moderately correlated (0.415) with objective measures.

Conclusion

Our results show that the most appropriate measure of objective physical function in RA patients is the 8′UG, followed by the 50′W. We found discordance between objectively and subjectively measured function. In clinical practice, an objective measure that is simple and quick to perform, such as the 8′UG, is advocated for assessing real functional status.

Effect of BMI, Body Fat Percentage and Fat Free Mass on Maximal Oxygen Consumption in Healthy Young Adults

INTRODUCTION

Maximal oxygen consumption (VO_2max) is an important measure of cardiorespiratory capacity of an individual at a given degree of fitness and oxygen availability. Risk of cardiovascular diseases increases with increasing degree of obesity and a low level of VO_2max has been established as an independent risk factor for cardiovascular mortality.

AIM

To determine VO_2max in young adults and to find its correlation with Body Mass Index (BMI), Body Fat% and Fat Free Mass (FFM).

MATERIALS AND METHODS

Fifty four (male=30, female=24) healthy young adults of age group18-25 years after screening by Physical Activity Readiness Questionnaire (PAR-Q) participated in the study. Height was measured by stadiometer. Weight was measured by digital weighing scale with 0.1 kg sensitivity. Body fat% was measured by Bioelectrical Impedance Analysis (BIA) method. FFM was calculated by subtracting fat mass from the body weight. VO_2max (mL.kg^-1.min^-1) was obtained by Submaximal Exercise Test (SET) by first two stages of Bruce Protocol with the basis of linear relationship between Heart Rate (HR) and oxygen consumption (VO₂). Data were analysed statistically in GraphPad Prism software version 6.01 for windows.

RESULTS

VO_2max (mL.kg^-1.min^-1) of male (43.25±7.25) was significantly (p<0.001) higher than female (31.65±2.10). BMI showed weak negative correlation (r= -0.3232, p=0.0171) with VO_2max but Body Fat% showed strong negative correlation (r= -0.7505, p<0.001) with VO_2max. FFM positively correlated (r=0.3727, p=0.0055) with VO_2max.

CONCLUSION

Increased body fat is associated with decreased level of VO_2max in young adults. Obesity in terms of Fat% is a better parameter than BMI for prediction of low VO_2max.

Validity of the Nurses' health study physical activity questionnaire in estimating physical activity in adults with rheumatoid arthritis

Background

Patients with rheumatoid arthritis (RA) demonstrate reduced aerobic capacity, excess cardiovascular risk, mobility limitations and are less physically active than their healthy peers. Physical activity may decrease RA disease activity through its anti-inflammatory effects and psychological and health benefits. To successfully manage RA symptoms and reduce cardiovascular risks associated with RA through increased physical activity (PA), accurate physical activity assessments are critical. Accelerometry is an objective physical activity measure, but not widely used. Validity of the Nurses’ Health Study physical activity questionnaire II (NHSPAQ) has not been determined for estimation of physical activity in RA. This study examined NHSPAQ validity in adults with RA compared to accelerometry-based metabolic equivalents determined (METs) and results of performance tests. We hypothesized NHSPAQ scores would correlate moderately (0.4–0.5) with accelerometer physical activity estimates.

Methods

Thirty-five adults with RA (mean age [SD] 62 (Williams et. al, Health Qual Life Outcomes10:28, 2012) years, 28 females (80%) recruited from a hospital-based clinic registry participated in a one-week accelerometry trial. Medical data was compiled. Participants completed the NHSPAQ, a self-paced 20-m walk test, and modified timed step test. Participants wore an accelerometer for 7 consecutive days, then completed a physical activity log and another NHSPAQ. Metabolic equivalents (METs) were derived from NHSPAQ and accelerometers using standardized formulas. NHSPAQ METs were correlated with accelerometer METs and data from performance measures.

Results

Average disease duration was 21 years (SD = 11), 63% patients took biologics. The average weekly METs reported were 29 (SD = 33) and accelerometer METs were 33 (SD = 22). NHSPAQ METs correlated moderately with accelerometer-derived METs (r = 0.48 95% CI (0.15–0.70). Self-reported PA correlated moderately with Step Test performance (r = 0.50 95% CI (0.18–0.72).

Conclusion

Patients with RA exhibit low physical activity levels. General fitness measures were moderately correlated with physical activity levels. A moderate significant correlation existed between NHSPAQ and accelerometry METs. These preliminary data suggest the NHSPAQ may be useful to describe physical activity levels in this population.