Validity of Submaximal Step Tests to Estimate Maximal Oxygen Uptake in Healthy Adults

Investigating the accuracy of Apple Watch VO2 max measurements: A validation study

VO2 max is a measure of cardiorespiratory fitness and a key indicator of overall health. It is predictive of cardiovascular events and shows a strong inverse association with all-cause mortality. Increased cardiorespiratory fitness is associated with reductions in coronary artery disease, diabetes and cancer. Apple Watch offers a less resource-intensive and more feasible alternative to the gold standard assessment for VO2 max, indirect calorimetry, but the accuracy of its measurements remains uncertain. This study aimed to assess the validity of VO2 max estimates from Apple Watch in comparison to indirect calorimetry. Thirty participants wore an Apple Watch for 5-10 days to generate a VO2 max estimate. Subsequently, they underwent a maximal exercise treadmill test in accordance with the modified Åstrand protocol. The agreement between measurements from Apple Watch and indirect calorimetry was assessed using Bland-Altman analysis, mean absolute percentage error (MAPE), and mean absolute error (MAE). Overall, Apple Watch underestimated VO2 max, with a mean difference of 6.07 mL/kg/min (95% CI 3.77-8.38). Limits of agreement indicated variability between measurement methods (lower -6.11 mL/kg/min; upper 18.26 mL/kg/min). MAPE was calculated as 13.31% (95% CI 10.01-16.61), and MAE was 6.92 mL/kg/min (95% CI 4.89-8.94). These findings indicate that Apple Watch VO2 max estimates require further refinement prior to clinical implementation. However, further consideration of Apple Watch as an alternative to conventional VO2 max prediction from submaximal exercise is warranted, given its practical utility.

Self-assessment of cardiorespiratory fitness: evaluation of reliability and validity of a step test eliminating a step board

PURPOSE

Conventional assessment of cardiorespiratory fitness (CRF) requires specialized equipment and designated spaces, limiting accessibility. To address this, the modified National Institute of Occupational Safety and Health, Japan step test (mJST) was developed for self-assessment without a step board. This study evaluated the reliability and validity of the mJST.

METHODS

A total of 131 participants (49% female, aged 30-59) were divided into a derivation group (n = 82) to establish an estimated maximal oxygen consumption ( V ˙ O2 max) model using multiple regression, and validation group (n = 49) to test the accuracy of the model. All participants completed the mJST and a  V ˙ O2 max treadmill test. The mJST comprised whole-body exercise for 3min and 40s followed by a 2-min recovery period. Heart rates (HRs) during the mJST were self-recorded using a wrist-worn device and measured via electrocardiograph. Test-retest reliability and validity were assessed using intraclass correlation coefficients (ICCs) and Bland-Altman analysis.

RESULTS

Excellent test-retest reliability was observed with electrocardiograph HRs (ICC = 0.92); however, fair to good reliability was observed with the wrist-worn device (ICC = 0.75). Bland-Altman analysis showed that mJST overestimated  V ˙ O2 max by 1.24 mL·kg-1·min-1, likely owing to discrepancies in HR readings from the wrist-worn device. The correlation between estimated and measured  V ˙ O2 max was moderate (r = 0.68).

CONCLUSIONS

Eliminating the step board in step tests may aid in regular assessments of CRF to support ongoing health management. Despite limitations in device accuracy, the mJST demonstrated sufficient reliability and validity as a practical tool.

Hyperandrogenaemia, polycystic ovary syndrome, and physical fitness in women-a Northern Finland birth cohort study

OBJECTIVE

To investigate the independent associations of hyperandrogenaemia (HA) and polycystic ovary syndrome (PCOS) with physical fitness in women among the general population.

DESIGN

A population-based birth cohort study including 5889 women.

METHODS

Longitudinal associations of serum testosterone (T), free androgen index (FAI), and PCOS with cardiorespiratory fitness (CRF) (measured by heart rate after a submaximal exercise test) and grip strength over the 31 to 46 years of age timespan were examined using multivariable linear mixed models adjusted for time, body mass index, homeostatic model assessment of insulin resistance, physical activity and smoking. The results are reported as regression coefficients (β) with corresponding 95% confidence intervals [95% CI].

RESULTS

The third and fourth T and FAI quartiles were associated positively with higher heart rate after the submaximal exercise test in multivariable models indicating poorer CRF compared with women in Q1 of T and FAI (Q3: β of T = 1.58 [95% CI: 0.21 to 2.96], β of FAI = 1.97 [0.54 to 3.39]; Q4: β of T = 1.88 [0.46 to 3.30], β of FAI = 2.70 [1.15 to 4.25]). The second, third, and fourth quartiles of FAI were associated with higher grip strength in multivariable models compared with women in Q1 (Q2: β = 0.59 [0.04 to 1.14], Q3: β = 0.74 [0.16 to 1.30], Q4: β = 0.68 [0.06 to 1.27]). Excluding women with PCOS did not alter these results, while PCOS itself was not associated with CRF or grip strength.

CONCLUSION

Hyperandrogenaemia in premenopausal women was associated with poorer CRF but better grip strength, independently of PCOS, which suggests that HA, rather than PCOS, has an independent and complex association with physical fitness in premenopausal women.

The Effect of 6 Weeks of Dynamic Neuromuscular Stabilization Exercises on Motor Control, Cardiovascular Fitness, and Respiratory Performance in Overweight and Obese Women

Background: Obesity is linked to impairments in motor control, cardiovascular fitness, and respiratory function. Dynamic Neuromuscular Stabilization (DNS) aims to enhance core stability, diaphragmatic breathing, and neuromuscular coordination. This study investigated the effects of a 6-week DNS program on these functional outcomes in overweight and obese women. Methods: Thirty-six participants (aged 35-50 years, BMI: 25-34 kg/m2) were randomly assigned to either an experimental group (n = 18), which underwent DNS training, or a control group (n = 18), which received no intervention. The DNS program consisted of six weekly sessions (three supervised, three home-based), emphasizing core stabilization, diaphragmatic breathing, and neuromuscular coordination. Motor control (lumbar movement control tests), cardiovascular fitness (two-minute step test), and respiratory performance (breath-hold time, respiratory rate, and respiratory muscle strength) were assessed before and after the intervention. Results: The DNS group demonstrated significant improvements compared to the control group, with notable increases in motor control scores (p < .001) and cardiovascular fitness (p < .001). Additionally, inspiratory and expiratory breath-hold times (p < .001 for both), respiratory rate (p < .001), and maximum inspiratory and expiratory pressures (p < .001) showed substantial enhancements. No significant changes were observed in the control group. Conclusion: A 6-week DNS exercise program significantly improved motor control, cardiovascular fitness, and respiratory performance in overweight and obese women. These findings support DNS training as an effective intervention for enhancing core stability, breathing efficiency, and neuromuscular coordination, with potential applications in rehabilitation and health promotion.

Physical activity, fitness, and cardiac autonomic function among adults born postterm

Recent studies have suggested that adverse outcomes of postterm birth (≥42 completed weeks of gestation), including increased cardiometabolic risk factors, impaired glucose metabolism, and obesity, may extend into adulthood. We studied interconnected determinants of cardiovascular health, including physical activity (PA; based on accelerometry for 2 weeks), muscular strength (measured by handgrip strength), cardiorespiratory fitness (CRF; measured by 4-min step test), and cardiac autonomic function (heart rate [HR] recovery, HR variability, and baroreflex sensitivity) among 46-year-old adults from the Northern Finland Birth Cohort born postterm (n = 805) and at term (n = 2645). Adults born postterm undertook vigorous PA 2.0 min day-1 (95% CI, 0.4-3.7) less than term-born adults when adjusted for sex, age, and maternal- and pregnancy-related covariates in multiple linear regression. Postterm birth was associated with reduced CRF, based on a higher peak HR (2.1 bpm; 95% CI, 0.9-3.4) and slower HR recovery 30 s after the step test (-0.7 bpm; 95% CI, -1.3 to -0.1). Postterm birth was associated with less PA of vigorous intensity and CRF and slower HR recovery in middle age. Our findings reinforce previous suggestions that postterm birth should be included as a perinatal risk factor for adult cardiometabolic disease.

Effects of a physical therapist-driven individualized hybrid model of the exercise component of cardiac rehabilitation on patient outcomes: a prospective single group, time-series design

PURPOSE

The aim of this prospective single group, time-series study was to determine the feasibility, adherence, and effectiveness of an individualized physical therapist (PT)-driven hybrid model of the exercise component of cardiac rehabilitation (CR) that uses a novel intensity-recovery progression protocol (IRPP) and cardiac testing template (CTT) to assess achieved heart rate (HR) intensity, HR recovery, and intensity-recovery total to guide treatment.

METHODS

Assessment of a questionnaire, treadmill 6-min walk (6MW), 1-min sit-to-stand (1STS), 1-min step, and 1-min agility square tests were assessed on 100 participants. Compared to traditional CR the 36-visit 1:1 hybrid model was individualized using the IRPP program and CTT.

RESULTS

Adherence was 35% (timely) and 44% (overall) completion. The per-protocol analysis (PPA) and intent-to-treat (ITT) analysis suggest significant improvement in objective assessments baseline to visit 15 (PPA = 11 of 14) (ITT = 13 of 14), baseline to visit 30 (PPA = 12 of 14) (ITT = 12 of 14) and visit 15 to visit 30 (PPA = 9 of 14) (ITT = 10 of 14). Improvement beyond the minimal clinically important difference (MCID) was 94.3% in the 6MW and 91.4% in the 1STS.

CONCLUSIONS

The PT-driven IRPP program was feasible in terms of adherence and safety, showing significant improvement in a majority of assessments. Analysis of HR using the CTT may help clinical decision making for progression in CR.

Applying intervention mapping to develop a program for promoting short physical activity breaks during class time in upper secondary schools: the MOVE12 protocol study

Introduction

Physical inactivity is a global health challenge, exacerbated by increased screen time and sedentary behaviors. Enhancing physical activity levels at schools offers a promising approach to promote lifelong healthy habits.

Methods

This protocol paper outlines the MOVE12 pilot study, a 12-week intervention study designed to increase physical activity among Norwegian upper secondary school students through 6-7-min daily MOVE-breaks integrated into lessons. Developed using the six-phase Intervention Mapping (IM) protocol, grounded in the social-ecological model and self-determination theory, the intervention focuses on fostering motivation and creating a supportive environment. Key steps include needs assessment, performance objectives, theoretical methods, and program structuring for sustainability.

Results

Linear mixed models, t-tests, and regression analyses will evaluate quantitative outcomes, while qualitative focus groups will explore engagement and behavior change.

Discussion

MOVE12 provides insights into scalable school-based interventions addressing physical inactivity, highlighting the potential of the IM framework to establish sustainable health promotion strategies.

Validity and reliability of the step test to estimate maximal oxygen consumption in pediatric population

Cardiorespiratory fitness is the most important variable related to health and a strong predictor of mortality. However, it is rarely used in clinics due to costs, specialized equipment, space needs, and the requirements of expert staff such as an exercise physiologist, physician, or other health professional. This work aims to validate and test the reliability of a submaximal step test to estimate VO2max of 8-to 16-year-old pediatric populations as a simple and low-cost tool for clinical practice. A cross-sectional study included 242 children and adolescents (42.1% girls) aged 8-16. Cardiorespiratory fitness was determined by a maximal incremental test on a treadmill until exhaustion. The step test entailed maintaining a steady pace of 22 steps per minute for 3 min (60 bpm), with the heart rate being recorded at the end of the test. Nutritional status was computed through BMI z-score. A multiple linear regression model validated the step test and developed a new equation to predict VO2max, including the third-minute heart rate, weight, and height. The reliability among predicted and measured VO2max was assessed by Bland-Altman analysis. The mean age was 12.5 ± 2.6; 51.6% were overweight or obese. The cardiorespiratory fitness measured as VO2max was 35.01 ± 0.58 ml·min-1·kg-1. A robust correlation was observed between the predicted VO2max from the step test and the measured VO2max (r = 0.86, p < 0.001). Bland-Altman analysis indicated statistical concordance between predicted and measured VO2max. Our findings indicate that the step test protocol is valid and reliable for estimating VO2max in children and adolescents. Furthermore, the predictive equation is suitable for application among children aged 8-16.

Assessment and repeatability of aerobic capacity using the Chester Step Test among current, former, and never smokers

Cigarette smoking contributes to reduced cardiorespiratory performance, which may improve upon cessation. Consequently, former smokers' cardiorespiratory fitness should not be significantly different from that of never-smokers. This study aims to compare V̇O2max values among current, former, and never smokers and assess the repeatability of measurements using the Chester Step Test (CST). V̇O2max measurements were available from a total of 70 subjects (23 current, 23 former, and 24 never-smokers) and showed significant repeatability. Current smokers had the worst aerobic capacity, with a mean VO2max ± SD of 38.8 ± 4.5, which was significantly lower than the VO2max of 41.62 ± 3.8 in never-smokers (p < 0.0001) and 41.43 ± 4.6 in former smokers (p < 0.0001). No significant differences were observed between never-smokers and former smokers. V̇O2max estimates by CST were reproducible and showed that the aerobic capacity of individuals who smoke is substantially inferior compared to never and former smokers. Improvement in cardiorespiratory performance following smoking cessation may have important implications for smoking cessation, especially for those smokers who perceive enhanced physical performance as a tangible benefit.

Bibliometric Review of the Step Test: A Comprehensive Analysis of Research Trends and Development

BACKGROUND

The step test provides valuable information on cardiorespiratory parameters such as maximal oxygen uptake and heart rate. Cardiorespiratory capacity is critical to health-related fitness, with heart rate recovery after exercise serving as a predictor of mortality risk.

MAIN BODY

The primary objective of this review was to identify trends, key contributors, and emerging themes in the step test literature through 2023 using the Web of Science Core Collection. Bibliometric data extraction and analysis were performed using a dedicated bibliometric software (VOSviewer). The analysis showed continued interest through 2021. The research categories highlight the multidisciplinary nature of the step test, covering cardiovascular systems, respiratory systems, sports sciences, and medicine. It has gained global attention, with 31 countries involved, with Brazil and the United States leading the way. The diversity of contributing nations is increasing, reflecting a growing global interest. With 111 journals involved, such as Respiratory Care and Medicine and Science in Sports and Exercise, step test research is spread across the academic landscape. With 761 contributing researchers, there is a collaborative and diverse community. The top 10 institutions, including the University of Alabama System and Monash University, illustrate the variety of settings in which step test studies are conducted. Step test studies span multiple disciplines, underscoring their adaptability. The clusters identified in this bibliometric analysis of the step test literature guide future research, suggesting avenues for refining protocols, exploring health implications, optimizing tests for specific conditions such as chronic obstructive pulmonary disease, and adapting step tests in diverse populations.

CONCLUSIONS

Practical implications highlight the role of the step test in cardiovascular risk assessment, fitness monitoring, and rehabilitation. This broad review underscores the relevance of the step test in diverse settings, reflecting its adaptability and ease of application across occupational and clinical settings.

Maximal Oxygen Consumption Is Negatively Associated with Fat Mass in Facioscapulohumeral Dystrophy

Facioscapulohumeral dystrophy (FSHD) leads to progressive changes in body composition such as loss of muscle mass and increase in adiposity. In healthy subjects, anthropometric parameters are associated with the maximum volume of oxygen consumed per minute (VO2max), which is a health and function indicator in several populations of subjects, both healthy and pathological. Since VO2max can be difficult to test in patients with FSHD due to exercise intolerance, the identification of associated anthropometric parameters could provide new easily obtainable elements for the patients' clinical stratification. The aim of this study was to evaluate whether anthropometric and body composition parameters are associated with VO2max in patients with FSHD. A total of 22 subjects with a molecular genetics-based diagnosis of FSHD (6 females, 16 males, mean age of 35.18 years) were recruited for the study. VO2max was measured by cardiopulmonary exercise tests (CPETs) on a cycle ergometer, utilizing a step incremental technique (15 Watts (W) every 30 s). Weight (Kg) and height (m) were obtained and utilized to calculate body mass index (BMI). Body composition parameters (fat mass (FM), fat free mass (FFM), and body cell mass (BCM)) were obtained by bioelectrical impedance analysis (BIA). Significant negative associations were found between VO2max and FM (Spearman correlation coefficient (SCC) -0.712), BMI (SCC -0.673), age (SCC -0.480), and weight (SCC -0.634), unlike FFM and BCM. Our results indicate that FM, BMI, age, and body weight are negatively associated with VO2max in patients with FSHD. This evidence may help practitioners to better stratify patients with FSHD.

Reliability, validity, usefulness, and sensitivity of a submaximal test of performing burpees in 3 minutes, in assessing and detecting changes in aerobic fitness of athletes during future prolonged self-isolation in a confined environment

BACKGROUND

During a prolonged quarantine, there is a need to monitor aerobic fitness levels of trained individuals who are isolated with a simple fitness test that can be performed in confined space of their own homes. This study examined the reliability, validity, usefulness and sensitivity of a novel 3-min submaximal heart rate burpees test (or SubHR3-MBT) to assess and monitor changes in aerobic fitness, of trained athletes. In the SubHR3-MBT, male and female athletes performed 48 and 39 burpees respectively, within 3 min by following a constant beeping pace. The performance criterion of the SubHR3-MBT is the highest heart rate attained (or exercise HRpeak) at the end of 3-min (wherein a lower exercise HRpeak indicates a higher level of aerobic fitness).

METHODS

A total of 40 male and female national athletes from various sports volunteered for the study.

RESULTS

For reliability (Part 1), the SubHR3-MBT showed good relative and excellent reliability, with intraclass correlation coefficient 0.90 and coefficient of variation 2.6%, respectively. For validity (Part II), there was significant negative correlation between relative exercise HRpeak with respiratory gas-measured VO2max (r=-0.51, large; P<0.001). The test's technical error of measurement of 2.3 is slightly greater than its smallest worthwhile change of 1.5. For sensitivity (Part III), the athletes were tested twice for their SubHR3-MBT and VO2max, once at baseline and another at a followed-up test after >10 weeks. There was a significant correlation between the % change in relative exercise HRpeak with the % change in VO2max (r=-0.66, large; P<0.001).

CONCLUSIONS

The SubHR3-MBT is a reliable, valid, marginally useful test and may be able to track changes in aerobic fitness in trained athletes with moderate levels of sensitivity, in case of future isolation due to pandemic occurrence.

Validity of submaximal aerobic capacity and strength tests in firefighters

BACKGROUND

Typically, the fitness of UK firefighters is assessed via submaximal estimate methods due to the low demands on time, money, expertise and equipment. However, the firefighter-specific validity of such testing in relation to maximum aerobic capacity (V˙O2max) and particularly muscular strength is not well established.

AIMS

To examine the validity of submaximal methods to estimate V˙O2max and maximal strength in operational firefighters.

METHODS

Twenty-two full-time operational firefighters (3 female) completed same-day submaximal (Chester Step Test; CST) and maximal (treadmill) assessments of V˙O2max, with a sub-sample of 10 firefighters (1 female) also completing submaximal and maximal back-squat (i.e. one repetition maximum; 1RM) assessments. All participants then completed the Firefighter Simulation Test (FFST) within 2-4 days.

RESULTS

CST underestimated actual V˙O2max by 1.4 ml·kg-1·min-1 (~3%), although V˙O2max values were positively correlated (r = 0.61, P < 0.01) and not significantly different. Estimated V˙O2max values negatively correlated with FFST performance (r = -0.42). Predicted 1RM underestimated actual 1RM by ~2%, although these values were significantly correlated (r = 0.99, P < 0.001) and did not significantly differ. The strongest predictive model of FFST performance included age, body mass index, and direct maximal measures of 1RM and V˙O2max.

CONCLUSIONS

Submaximal back-squat testing offers good validity in estimating maximum firefighter strength without exposure to the fatigue associated with maximal methods. The CST provides a reasonably valid and cost-effective V˙O2max estimate which translates to firefighting task performance, although the error observed means it should be used cautiously when making operational decisions related to V˙O2max benchmarks.

Smartphone-based inertial measurements during Chester step test as a predictor of length of hospital stay in abdominopelvic cancer postoperative period: a prospective cohort study

BACKGROUND

Objective assessment of pre-operative functional capacity in cancer patients using the smartphone gyroscope during the Chester step (CST) test may allow greater sensitivity of test results. This study has investigated whether the CST is a postoperative hospital permanence predictor in cancer patients undergoing abdominopelvic surgery through work, VO2MAX and gyroscopic movement analysis.

METHODS

Prospective, quantitative, descriptive and inferential observational cohort study. Fifty-one patients were evaluated using CST in conjunction with a smartphone gyroscope. Multivariate linear regression analysis was used to examine the predictive value of the CST.

RESULTS

The duration of hospital permanence 30 days after surgery was longer when patients who performed stage 1 showed lower RMS amplitude and higher peak power. The work increased as the test progressed in stage 3. High VO2MAX seemed to be a predictor of hospital permanence in those who completed levels 3 and 4 of the test.

CONCLUSION

The use of the gyroscope was more accurate in detecting mobility changes, which predicted a less favorable result for those who met at level 1 of the CST. VO2MAX was a predictor of prolonged hospitalization from level 3 of the test. The work was less accurate to determine the patient's true functional capacity.

Effectiveness of digital health interventions to increase cardiorespiratory fitness: A systematic review and meta-analysis

Background

Interventions using commercial digital health tools do favorably affect health outcomes. However, the effect of digital tools on cardiorespiratory fitness, a more novel indicator cardiovascular risk, is unclear.

Purpose

Synthesize the digital health intervention literature and answer the following question: What is the effect of interventions using mobile health apps, wearable activity trackers, and/or text messaging on cardiorespiratory fitness?

Methods

A systematic review and a meta-analysis (PROSPERO CRD42023423925) were conducted to evaluate the immediate digital health intervention effect on adult cardiorespiratory fitness. In March 2023, a search of databases Embase, MEDLINE, CINHAL, and Cochrane Library was completed. Studies were included if the intervention used a mobile health app, text messaging, and/or activity tracker. Studies were excluded if an objective measure of fitness was not used; the sample included children; the setting was hospital-based; and the digital health technology was only used for data collection or described as virtual reality. Using a random-effects model, two separate meta-analyses were completed: one for single-group studies and one for multi-group studies. Standardized mean difference effect sizes (Cohen's d) were calculated. Study quality was evaluated with the Cochrane Risk of Bias tool and ROBINS-I tool.

Results

Fifty-three studies (3657 individuals) with pre-post designs (12 single-group, 41 multi-group) were included. Most studies targeted participants with a specific chronic health condition. Digital health interventions in the single-group studies had a moderate-to-large effect size (d = 0.62, 95% confidence interval (CI) [0.41-0.84], p < 0.001), and multi-group studies had small-to-moderate effect size (d = 0.38, 95% CI 0.21-0.55, p < 0.001). Significant heterogeneity of effects was observed in both the single-group and multi-group studies.

Conclusions

Interventions using text messaging, a mobile app, or activity tracker alone or in combination are effective in improving cardiorespiratory fitness in adults, particularly for those with a chronic health condition.

Effects of implementing a mandatory and consequential annual fitness assessment in a fire department over the initial 4-year period

BACKGROUND

Despite the physical nature of the occupation many firefighters have low levels of physical fitness which is associated with poor performance of occupational tasks and increased injury rates. For many fire departments an initial step in promoting health and wellness within the department is to conduct annual fitness testing.

OBJECTIVE

To examine the effects of implementing a consequential fitness assessment within a fire department.

METHODS

A retrospective repeated measures design was used to analyze annual fitness assessment data of professional firefighters (n = 1415) from 2019 to 2022 within a large urban fire department located in the mid-Atlantic region of the United States. The fitness tests included assessments of pull-ups, push-ups, sit-ups, aerobic capacity, and body composition. Repeated measure analyses of variances (ANOVAs) assessed the effect of year and a 2-way ANOVA was conducted to investigate the effects of sex and age on fitness measures on 2022 data.

RESULTS

All fitness measures were found to be maintained over the 4-year period. Significant main effects of age and sex across all fitness measures, but no significant interactions were found. Older firefighters (50 + years) exhibited lower performance (p < 0.001, d > 0.80) on muscular fitness assessments than young firefighters (20-29 years). A large effect of sex (males > females) was found for pull-ups (d = 1.04), push-ups (d = 1.23), and aerobic capacity (d = 1.38).

CONCLUSIONS

The results suggest that implementing a consequential fitness assessment could help maintain firefighters' fitness levels over a multi-year period.

The Relationship of the PROMIS® Pediatric Physical Activity Measure with Cardiorespiratory Fitness

A The PROMIS® Pediatric Physical Activity (PA) measure is a new instrument with established validity that measures a child self-report on short bouts of moderate to rigorous physical activity. The purpose of this study was to explore the relationship of the PROMIS® Pediatric PA item bank with cardiorespiratory fitness and self-efficacy. The study was conducted at the Minnesota State Fair. Youth ages 8 to 18 years completed the PROMIS® Pediatric PA and the Self-Efficacy for PA measures on an iPad. Participants performed 3-min step test with heart rates measured 1 min posttest. Participants (N = 182) were 53% female. The PROMIS® Pediatric PA had a weak, significant negative correlation with the step test measurement (r = -0.23, p = 0.001) and a weak, significant positive correlation with self-efficacy (r = 0.27, p < 0.001). Measurements did not differ between groups by sex or age group (school-age and adolescent). Youth who were obese had significantly higher heart rates post step test (p = 0.004); BMI percentile groups did not differ in other measures. Self-report of PA and the physiologic measure of heart rate are from two related but different physical fitness domains which supports their significant but weak relationship.

Assessment of Cardiorespiratory Fitness in 8-to-15-Year-Old Children with Overweight/Obesity by Three-Minute Step Test: Association with Degree of Obesity, Blood Pressure, and Insulin Resistance

OBJECTIVE

To assess cardiorespiratory fitness in children and adolescents with overweight/obesity using the Kasch pulse recovery (KPR) test, and its correlation with severity of obesity, insulin resistance, and blood pressure (BP).

METHODS

This is a retrospective analysis of baseline data from a study evaluating the efficacy of yoga for reduction of body mass index (BMI) in children aged 8-15 y with overweight/obesity. KPR three-minute step test was done. Children were classified into cardiorespiratory fitness categories based on the post-KPR heart rate (HR); the maximal oxygen consumption (VO2 max) was calculated, and the correlation analysis was done.

RESULTS

One hundred fifty-five children with mean age of 11.6 ± 1.8 y and mean BMI of 26.2 ± 4.1 kg/m2 were included. Mean post-KPR-HR and calculated VO2 max were 119 ± 14 per minute and 48.7 ± 5.6 mL/kg/min, respectively. In children < 13 y, cardiorespiratory fitness was excellent or very good in 28%, good or sufficient in 58%, and poor or very poor in 14%. BMI, waist circumference (WC), resting HR, systolic BP, and homeostatic model of insulin resistance (HOMA-IR) were higher among those with poor/very poor fitness, with WC z score being statistically significant (p = 0.015). Post-KPR-HR showed positive correlation with BMI z score (r = 0.16, p = 0.044), WC z score (r = 0.21, p = 0.011), and HOMA-IR (r = 0.22, p = 0.012).

CONCLUSION

In children with overweight/obesity, 14% had poor cardiorespiratory fitness. Post-KPR-HR and calculated VO2 max had good correlation with measures of obesity and HOMA-IR. Further studies evaluating cardiorespiratory fitness and normative data of VO2 max for Indian children are warranted.

Modeling personalized heart rate response to exercise and environmental factors with wearables data

Heart rate (HR) response to workout intensity reflects fitness and cardiorespiratory health. Physiological models have been developed to describe such heart rate dynamics and characterize cardiorespiratory fitness. However, these models have been limited to small studies in controlled lab environments and are challenging to apply to noisy-but ubiquitous-data from wearables. We propose a hybrid approach that combines a physiological model with flexible neural network components to learn a personalized, multidimensional representation of fitness. The physiological model describes the evolution of heart rate during exercise using ordinary differential equations (ODEs). ODE parameters are dynamically derived via a neural network connecting personalized representations to external environmental factors, from area topography to weather and instantaneous workout intensity. Our approach efficiently fits the hybrid model to a large set of 270,707 workouts collected from wearables of 7465 users from the Apple Heart and Movement Study. The resulting model produces fitness representations that accurately predict full HR response to exercise intensity in future workouts, with a per-workout median error of 6.1 BPM [4.4-8.8 IQR]. We further demonstrate that the learned representations correlate with traditional metrics of cardiorespiratory fitness, such as VO2 max (explained variance 0.81 ± 0.003). Lastly, we illustrate how our model is naturally interpretable and explicitly describes the effects of environmental factors such as temperature and humidity on heart rate, e.g., high temperatures can increase heart rate by 10%. Combining physiological ODEs with flexible neural networks can yield interpretable, robust, and expressive models for health applications.

Feasibility of predicting maximal oxygen uptake by using the efficiency factor in healthy men

Conventionally, efficiency is indirectly estimated through a respiratory gas analyser (oxygen, carbon dioxide), which is a complex and rather costly calculation method that is difficult to perform in many situations. Therefore, the present study proposed a modified definition of efficiency, called the efficiency factor (EF) (i.e., the ratio of work to the corresponding exercise intensity), and evaluated the relation between the EF and maximal oxygen uptake ([Formula: see text]), as well as compared the prediction models established based on the EF. The heart rate (maximal heart rate: 186 ± 6 beats min-1), rating of perceived exertion (19 ± 1), and [Formula: see text] (39.0 ± 7.1 mL kg-1 min-1) of 150 healthy men (age: 20 ± 2 years; height: 175.0 ± 6.0 cm; weight: 73.6 ± 10.7 kg; body mass index [BMI]: 24.0 ± 3.0 kg m-2; percent body fat [PBF]: 17.0 ± 5.7%) were measured during the cardiopulmonary exercise test (CPET). Through multiple linear regression analysis, we established the BMI model using age and BMI as parameters. Additionally, we created the PBF modelHRR utilizing weight, PBF, and heart rate reserve (HRR) and developed PBF modelEF6 and PBF modelEF7 by incorporating EF6 from the exercise stage 6 and EF7 from the exercise stage 7 during the CPET, respectively. EF6 (r = 0.32, p = 0.001) and EF7 (r = 0.31, p = 0.002) were significantly related to [Formula: see text]. Among the models, the PBF modelEF6 showed the highest accuracy, which could explain 62.6% of the variance in the [Formula: see text] at with a standard error of estimate (SEE) of 4.39 mL kg-1 min-1 (%SEE = 11.25%, p < 0.001). These results indicated that the EF is a significant predictor of [Formula: see text], and compared to the other models, the PBF modelEF6 is the best model for estimating [Formula: see text].

Positive Effects of Physical Activity on Prescription on Glycemic Control, Fitness, and Quality of Life in Newly Diagnosed Type 2 Diabetic Patients

The aim was to investigate the effects of physical activity on prescription (PAP) compared with standard care (SC) in adult drug-naïve T2D patients. A randomized control trial was conducted with drug-naïve T2D patients attending an out-patient clinic Vietnam. Participants were randomly assigned to the PAP group (n+=+44) or the SC group (n+=+43). The PAP group received individualized recommendations for PA, intensive face-to-face training every two weeks. The SC group received the standard recommendations according to WHO guidelines. The mean HbA1c level change was larger (-10.6±6.4 mmol/mol) in the PAP group than in the SC group (-2.4±5.8 mmol/mol) (p<0.001). A one thousand step counts per day increase was significantly associated with a decrease of -2.43 mmol/mol in HbA1c [β=-2.43, 95%CI: (-2.94, -1.92]) in the PAP group. The fasting plasma glucose levels of the PAP group decreased significantly compared with the SC group. The VO2-max increased significantly more in the PAP group than in the SC group. PAP had clear positive effects on health-related Quality of Life [mean between group difference: 9.54 (95%CI 5.84,13.23)]. Insulin resistance, BMI, waist circumference, total cholesterol, LDL cholesterol and triglycerides were significantly more decreased in the PAP group than in the control group. In conclusion, the fact that even a small change in mean step counts over three months had a beneficial effect on health-related outcomes in drug-naïve T2D patients can have large implications for treatment and management practices, not least in a middle-income country like Vietnam.

Estimation methods to detect changes in cardiorespiratory fitness due to exercise training and subsequent detraining

PURPOSE

To determine whether estimated maximal oxygen consumption ([Formula: see text]) can detect cardiorespiratory fitness (CRF) changes by behavioral modifications. This study compared changes in measured [Formula: see text]O_2max (m[Formula: see text]O_2max) through exercise intervention with e[Formula: see text]O_2max using a multiple regression model (MRM) and linear extrapolation method (LEM).

METHODS

A cross-sectional analysis involving 173 adults was conducted to establish an MRM by including age, sex, body mass index, questionnaire score, heart rate (HR) from step test, and m[Formula: see text]O_2max. Subsequently, 15 men participated in an intervention experiment comprising an 8-week, high-intensity interval training, followed by 8-week detraining, and completed anthropometric measurements, questionnaires, step tests, and m[Formula: see text]O_2max tests. m[Formula: see text]O_2max changes throughout the intervention were compared to e[Formula: see text]O_2max changes calculated using the MRM and LEM. The LEM used the HR during the step test with constant values (predetermined [Formula: see text]O₂), such as the Chester step test.

RESULTS

Inclusion of the step test HR in a questionnaire-based MRM improved the estimation power, although the MRM underestimated higher m[Formula: see text]O_2max values. In the intervention, m[Formula: see text]O_2max increased by 20.0 ± 14.1% (P < 0.01) and subsequently decreased by 9.5 ± 6.6% (P < 0.01) after exercise training and detraining, respectively. Significant method × time interactions were observed between m[Formula: see text]O_2max and e[Formula: see text]O_2max in the MRM but not in the LEM, i.e., an apparent systematic error (underestimation of high values) of the MRM was absent in the LEM, although the correlation between m[Formula: see text]O_2max and e[Formula: see text]O_2max using the LEM was moderate.

CONCLUSION

e[Formula: see text]O_2max, particularly using the MRM with HR as an explanatory factor, is not an appropriate method for detecting CRF changes along with behavioral modifications.

CLINICAL TRIAL REGISTRATION

Registered number, UMIN000041031; Registered date, 2020/07/08; URL, https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000046855.

The effects of a 1-year recreational football protocol on bone health parameters in a group of healthy inactive 50-year-old men

The main aim of the current study was to explore the effects of a 1-year recreational football protocol on bone health parameters (bone mineral content (BMC), bone mineral density (BMD), femoral neck geometry and composite indices of femoral neck strength) in a group of healthy inactive 50-year-old men. 51 middle-aged men voluntarily participated in this study, but only 41 of them completed it. Thus, the study population included 11 former football (FF) players and 30 inactive men. Inactive men were assigned to 3 different groups: controls (n=10), recreational football 30 (RF30; n=10) and recreational football 60 (RF60; n=10). The RF30 group performed two sessions of recreational football per week; the duration of each session was 30 minutes. The RF60 group performed two sessions of recreational football per week; the duration of each session was 60 minutes. The current study has demonstrated that whole body (WB) BMC, femoral neck BMD, cross-sectional moment of inertia, compression strength index, bending strength index and impact strength index increased in both experimental groups (RF30 and RF60) but not in the control group. The percentages of variations in bone health parameters were not significantly different between RF30 and RF60. In conclusion, this study suggests that recreational football is an effective method to improve bone health parameters in middle-aged men. In the studied population, most of the bone health benefits occurred after a low volume training protocol (2 * 30 minutes of recreational football per week).

Feasibility of Seated Stepping and Handshaking as a Cardiopulmonary Exercise Testing: A Pilot Study

Cardiopulmonary function is usually assessed by cardiopulmonary exercise testing (CPX) using a cycle ergometer (CE-CPX) or a treadmill, which is difficult in patients with lower extremity motor dysfunction. A stepping and handshaking (SHS) exercise has been developed that can be performed safely and easily while sitting on a chair. This study compared peak oxygen uptake (peak V.O2) between CE-CPX and SHS-CPX in healthy adults and investigated the safety and validity of SHS-CPX. Twenty young adults (mean age 27.8 ± 4.4 years) were randomly assigned to perform CE-CPX or SHS-CPX, with the other test to follow 1–2 weeks later. The peak V.O2, respiratory exchange ratio (RER), peak heart rate, blood pressure, and test completion time were compared between CE-CPX and SHS-CPX. All subjects completed the examination and met the criteria for peak V.O2. SHS-CPX and CE-CPX showed a strong correlation with peak V.O2 (r = 0.85, p < 0.0001). The peak V.O2 (40.4 ± 11.3 mL/min/kg vs. 28.9 ± 8.0 mL/min/kg), peak heart rate (190.6 ± 8.9 bpm vs. 172.1 ± 12.6 bpm), and test completion time (1052.8 ± 143.7 s vs. 609.1 ± 96.2 s) were significantly lower in the SHS-CPX (p < 0.0001). There were no adverse events. The peak V.O2 with SHS-CPX was equivalent to about 70% of that with CE-CPX despite the exercise being performed in a sitting position, suggesting its suitability as a submaximal exercise test.

Leisure-time physical activity, occupational physical activity and the physical activity paradox in healthcare workers: A systematic overview of the literature

BACKGROUND

Physical activity positively influences cardiovascular health. Results from male-dominated physically active occupations suggest that a high level of occupational physical activity may be detrimental to cardiovascular health. This observation is referred to as the physical activity paradox. Whether this phenomenon can also be observed in female-dominated occupations remains unknown.

OBJECTIVE

We aimed to provide an overview of (1) leisure-time and occupational physical activity in healthcare workers. Therefore, we reviewed studies (2) to assess the relationship between the two physical activity domains and analyzed (3) their effects on cardiovascular health outcomes in relation to the paradox.

METHODS

Five databases (CINAHAL, PubMed, Scopus, Sportdiscus, Web of Science) were systematically searched. Both authors independently screened the titles, abstracts, and full texts and assessed the quality of the studies using the National Institutes of Health's quality assessment tool for observational cohort and cross-sectional studies. All studies that assessed leisure-time and occupational physical activity in healthcare workers were included. The two authors independently rated the risk of bias using the ROBINS-E tool. The body of evidence was evaluated using the GRADE approach.

RESULTS

The review included 17 studies that assessed the leisure-time and occupational physical activity of people working in healthcare, determined the relationship between the domains (n = 7) and/or examined their effects on the cardiovascular system (n = 5). Measurements for leisure-time and occupational physical activity varied between studies. Leisure-time physical activity typically ranged between low and high intensity, with a short duration (approx. 0.8-1.5 h). Occupational physical activity was typically performed at light to moderate intensity with a very long duration (approx. 0.5-3 h). Moreover, leisure-time and occupational physical activity were almost negatively related. The few studies investigating effects on cardiovascular parameters revealed a rather unfavorable effect of occupational physical activity, while leisure-time physical activity was beneficial. The study quality was rated as fair and the risk of bias was moderate to high. The body of evidence was low.

CONCLUSIONS

This review confirmed that leisure-time and occupational physical activity of healthcare workers are opposed in their duration and intensity. Moreover, leisure-time and occupational physical activity seem to be negatively related and should be analyzed according to their relation to each other in specific occupations. Furthermore, results support the relationship between the paradox and cardiovascular parameters.

REGISTRATION

Preregistered on PROSPERO (CRD42021254572). Date of registration on PROSPERO: 19 May 2021.

TWEETABLE ABSTRACT

Does occupational physical activity adversely affect the cardiovascular health of healthcare workers in comparison to leisure-time physical activity?

Replacing sedentary time with physical activity and sleep: Associations with cardiometabolic health markers in adults

This study aimed to examine the associations of sedentary time, and substituting sedentary time with physical activity and sleep, with cardiometabolic health markers while accounting for a full 24 h of movement and non-movement behaviors, cardiorespiratory fitness (CRF), and other potential confounders. The participants were 4585 members of the Northern Finland Birth Cohort 1966, who wore a hip-worn accelerometer at the age of 46 years for 14 consecutive days. Time spent in sedentary behaviors, light-intensity physical activity (LPA), and moderate-to-vigorous-intensity physical activity (MVPA) were determined from the accelerometer and combined with self-reported sleep duration to obtain the 24-h time use. CRF was estimated from the peak heart rate in a submaximal step test. An isotemporal substitution paradigm was used to examine how sedentary time and substituting sedentary time with an equal amount of LPA, MVPA, or sleep were associated with adiposity markers, blood lipid levels, and fasting glucose and insulin. Sedentary time was independently and adversely associated with the markers of cardiometabolic health, even after adjustment for CRF, but not in partition models including LPA, MVPA, sleep, and CRF. Substituting 60, 45, 30, and 15 min/day of sedentary time with LPA or MVPA was associated with 0.2%-13.7% favorable differences in the cardiometabolic health markers after accounting for LPA, MVPA, sleep, CRF, and other confounders. After adjustment for movement and non-movement behaviors within the 24-h cycle, reallocating additional time to both LPA and MVPA was beneficially associated with markers of cardiometabolic health in middle-aged adults regardless of their CRF level.

Adherence to unsupervised exercise in sedentary individuals: A randomised feasibility trial of two mobile health interventions

Introduction

Adherence to unsupervised exercise is poor, yet unsupervised exercise interventions are utilised in most healthcare settings. Thus, investigating novel ways to enhance adherence to unsupervised exercise is essential. This study aimed to examine the feasibility of two mobile health (mHealth) technology-supported exercise and physical activity (PA) interventions to increase adherence to unsupervised exercise.

Methods

Eighty-six participants were randomised to online resources (n = 44, females n = 29) or MOTIVATE (n = 42, females n = 28). The online resources group had access to booklets and videos to assist in performing a progressive exercise programme. MOTIVATE participants received exercise counselling sessions supported via mHealth biometrics which allowed instant participant feedback on exercise intensity, and communication with an exercise specialist. Heart rate (HR) monitoring, survey-reported exercise behaviour and accelerometer-derived PA were used to quantify adherence. Remote measurement techniques were used to assess anthropometrics, blood pressure, HbA1c and lipid profiles.

Results

HR-derived adherence rates were 22 ± 34% and 113 ± 68% in the online resources and MOTIVATE groups, respectively. Self-reported exercise behaviour demonstrated moderate (Cohen's d = 0.63, CI = 0.27 to 0.99) and large effects (Cohen's d = 0.88, CI = 0.49 to 1.26) in favour of online resources and MOTIVATE groups, respectively. When dropouts were included, 84% of remotely gathered data were available, with dropouts removed data availability was 94%.

Conclusion

Data suggest both interventions have a positive impact on adherence to unsupervised exercise but MOTIVATE enables participants to meet recommended exercise guidelines. Nevertheless, to maximise adherence to unsupervised exercise, future appropriately powered trials should explore the effectiveness of the MOTIVATE intervention.

Improved VO2max Estimation by Combining a Multiple Regression Model and Linear Extrapolation Method

Maximal oxygen consumption (VO_2max) is an important health indicator that is often estimated using a multiple regression model (MRM) or linear extrapolation method (LEM) with the heart rate (HR) during a step test. Nonetheless, both methods have inherent problems. This study investigated a VO_2max estimation method that mitigates the weaknesses of these two methods. A total of 128 adults completed anthropometric measurements, a physical activity questionnaire, a step test with HR measurements, and a VO_2max treadmill test. The MRM included step-test HR, age, sex, body mass index, and questionnaire scores, whereas the LEM included step-test HR, predetermined constant VO₂ values, and age-predicted maximal HR. Systematic differences between estimated and measured VO_2max values were detected using Bland-Altman plots. The standard errors of the estimates of the MRM and LEM were 4.15 and 5.08 mL·kg^-1·min^-1, respectively. The range of 95% limits of agreement for the LEM was wider than that for the MRM. Fixed biases were not significant for both methods, and a significant proportional bias was observed only in the MRM. MRM bias was eliminated using the LEM application when the MRM-estimated VO_2max was ≥45 mL·kg^-1·min^-1. In conclusion, substantial proportional bias in the MRM may be mitigated using the LEM within a limited range.

The Chester Step Test Is a Reproducible Tool to Assess Exercise Capacity and Exertional Desaturation in Post-COVID-19 Patients

Many people recovering from an acute episode of coronavirus disease (COVID-19) experience prolonged symptoms. Exercise testing is a feasible and cost-effective option for assessing exercise tolerance, fatigue, and dyspnea related to effort. Being that the Chester step test (CST) is a progressive, submaximal test for predicting aerobic capacity, it could be a good option to explore. This study aimed to determine the reproducibility of CST for assessing exertional desaturation and exercise capacity in patients post-COVID-19 disease. A cross-sectional study was conducted on post-COVID-19 patients. Two attempts of the CST were performed. The intraclass correlation coefficient (ICC) was used to assess agreement between the two tests. Forty-two symptomatic post-COVID-19 patients were included, the mean age was 53.8 ± 10.3 years, and 52% were female. There was no significant difference between both tests (p = 0.896). Twenty-four percent of participants (10 cases) had a clinically significant decrease in SpO2 at the first assessment, compared to 30.1% (13 cases) at the second, with no significant difference. An ICC of 0.993 (95% CI: 0.987 to 0.996) was obtained for the total number of steps in the CST.

Joint Profiles of Sedentary Time and Physical Activity in Adults and Their Associations with Cardiometabolic Health

PURPOSE

This study aimed to identify and characterize joint profiles of sedentary time and physical activity among adults and to investigate how these profiles are associated with markers of cardiometabolic health.

METHODS

The participants included 3702 of the Northern Finland Birth Cohort 1966 at age 46 yr, who wore a hip-worn accelerometer during waking hours and provided seven consecutive days of valid data. Sedentary time, light-intensity physical activity, and moderate- to vigorous-intensity physical activity on each valid day were obtained, and a data-driven clustering approach ("KmL3D") was used to characterize distinct joint profiles of sedentary time and physical activity intensities. Participants self-reported their sleep duration and performed a submaximal step test with continuous heart rate measurement to estimate their cardiorespiratory fitness (peak heart rate). Linear regression was used to determine the association between joint profiles of sedentary time and physical activities with cardiometabolic health markers, including adiposity markers and blood lipid, glucose, and insulin levels.

RESULTS

Four distinct groups were identified: "active couch potatoes" ( n = 1173), "sedentary light movers" ( n = 1199), "sedentary exercisers" ( n = 694), and "movers" ( n = 636). Although sufficiently active, active couch potatoes had the highest daily sedentary time (>10 h) and lowest light-intensity physical activity. Compared with active couch potatoes, sedentary light movers, sedentary exercisers, and movers spent less time in sedentary by performing more physical activity at light-intensity upward and had favorable differences in their cardiometabolic health markers after accounting for potential confounders (1.1%-25.0% lower values depending on the health marker and profile).

CONCLUSIONS

After accounting for sleep duration and cardiorespiratory fitness, waking activity profiles characterized by performing more physical activity at light-intensity upward, resulting in less time spent in sedentary, were associated with better cardiometabolic health.

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.

Impact of mild COVID-19 on balance function in young adults, a prospective observational study

Balance is of essential importance in human life. The aim of the study is to examine the incidence of balance impairments in young adults who have recovered from mild COVID-19. The study involved 100 subjects, divided into two groups: the study group (50 individuals) comprised subjects who had recovered from mild COVID-19, and the control group (50 individuals) consisted of healthy subjects matched for gender and age. Balance was assessed using a force platform and clinical tests such as: timed up and go test, 15-s step test, sit-to-stand test and 6-min walk test. The assessment on the platform showed greater balance impairments in the trials with eyes closed; more specifically, compared to the controls, in trials with double-leg support the subjects from the study group acquired significantly higher scores in X average (lateral coordinates) (p < 0.05), Path length, V average (average Centre of Foot Pressure Velocity) (p < 0.05) and Area circular (p < 0.01), with even more significant results in trials with single-leg support in X average (p < 0.001), Y average (anterior–posterior coordinates) (p < 0.001) and Path length (p = 0.004). Higher scores in the timed up and go test were found in the study group (p = 0.013). The control group had higher scores in the remaining tests. The current findings show that mild COVID-19 may lead to balance impairments in young adults. Statistically significant differences in balance were found between the subjects in the study group and the healthy controls. Further studies in this area should take into account more age groups, and patients recovered from severe COVID-19, and should investigate long-term consequences of COVID-19 reflected by balance problems.

Feasibility of an Intervention Targeting Health through Exergaming as an Alternative to Routine Treatment (FIT HEART): protocol for a non-randomised two-armed pilot study

Background

Despite elevated risk of cardiometabolic disease among those with serious mental illness, and widespread recognition that physical activity interventions are required, there are multiple barriers to implementing typically recommended physical activity programmes in secure inpatient settings. Due to low mood, negative symptoms and poor socio-occupational functioning, psychiatric inpatients often lack motivation to engage in physical activity programmes. Moreover, regular access to outdoor spaces and exercise equipment is limited. As such, there is a need for novel physical activity interventions that are suitable for secure settings. This study aims to investigate the feasibility, acceptability and potential effectiveness of an intervention (exergaming) to promote physical activity among patients in a secure mental health setting.

Methods

This non-randomised, two-arm pilot study will employ a pre-test/post-test parallel group design, comparing the exergaming intervention with a “routine treatment” control. Two high-secure, sub-acute wards in the Long Bay Hospital Mental Health Unit will be non-randomly allocated to either the exergaming intervention or the “routine treatment” control group.

The intervention group will receive a 12-week programme comprising three 30-min exergaming sessions per week using various Xbox Kinect^TM activity-based games designed to simulate moderate intensity exercise. The “routine treatment” group will continue to receive the standard model of care delivered by the Justice Health and Forensic Mental Health Network. Accelerometers will be distributed to all participants to collect daily energy expenditure, number of steps taken, intensity of physical activity and heart rate data throughout the study.

The primary outcomes are (1) intervention feasibility and acceptability, and (2) baseline to post-intervention changes in physical health outcomes (levels of physical activity; cardiovascular fitness; clinical measures of cardiometabolic risk). Secondary outcomes are baseline to post-intervention changes in mental health outcomes (depression, anxiety, stress, positive psychiatric symptoms). Outcomes will be assessed at baseline, mid-intervention, and post-intervention.

Discussion

This research will contribute to evidence-based practice in the care of patients with serious mental illness: a vulnerable population with complex physical and mental health needs and a markedly elevated risk of cardiovascular disease. The findings will inform cardiovascular health promotion strategies and the implementation of physical activity interventions in secure inpatient settings.

Trial registration

ANZCTR, ACTRN12619000202167. Registered on 12 February 2019, https://www.anzctr.org.au. ANZCTR mandatory data items comply with the minimum dataset requirements of the World Health Organisation (WHO). The ANZCTR contributes trial registration data to the WHO International Clinical Trials Registry Platform (WHO ICTRP).

Supplementary Information

The online version contains supplementary material available at 10.1186/s40814-022-01068-2.

Impact of Physical Activity Differences Due to COVID-19 Pandemic Lockdown on Non-Alcoholic Fatty Liver Parameters in Adults with Metabolic Syndrome

BACKGROUND

A Mediterranean lifestyle with a Mediterranean diet and regular physical activity (PA) improves metabolic syndrome (MetS) characteristics and non-alcoholic fatty liver disease (NAFLD). The COVID-19 pandemic stopped healthy habits and increased NAFLD progression.

OBJECTIVES

To assess how PA differences due to COVID-19 lockdown affected NAFLD parameters in adults with MetS.

DESIGN

Longitudinal 2-year analysis of data obtained between COVID-19 pre- and post-lockdown in a parallel-group randomized trial (n = 57, aged 40-60 years old, with MetS and NAFLD).

METHODS

NAFLD status and related parameters were assessed by magnetic resonance imaging (MRI), blood collection analysis and related indexes. PA and fitness status were assessed by an Alpha-Fit test battery, accelerometers, validated Minnesota questionnaire and functional fitness score. During lockdown, study personnel telephoned patients to motivate them. Participants were grouped according to PA levels.

RESULTS

The low PA group improved its fitness score tests (0.2) after lockdown more than the medium PA group, and it decreased its sedentary activity (-48.7 min/day), increased light (20.9 min/day) and moderate (32.3 min/day) PA intensities and improved sleep efficiency (0.6%) in comparison with the medium and high PA groups. The high PA group increased its steps per day more than the other groups. The low PA group was the only group that decreased its gamma glutamyl transferase (GGT) levels (-17.0 U/L). All groups increased their fatty liver index (FLI) after lockdown, but the medium PA group increased its FLI more than the low PA group. Participants in the high PA group decreased their HDL-cholesterol levels more than participants in the medium PA group (-0.4 mg/dL).

CONCLUSIONS

Stopping regular PA together with an unhealthy lifestyle leads to a worsening of MetS and NAFLD. COVID-19 lockdown induced a decrease in PA in more active people, but inactive people increased their PA levels. Motivation seemed to be very important during lockdown.

Effect of a Six-Month Lifestyle Intervention on the Physical Activity and Fitness Status of Adults with NAFLD and Metabolic Syndrome

(1) Background: Physical inactivity has been linked to NAFLD, and exercise has been reported as useful to reduce intrahepatic fat content in NAFLD. (2) Objectives: To assess the physical activity (PA) and fitness status after a six-month lifestyle intervention (diet and PA) in adults with NAFLD and metabolic syndrome (MetS). (3) Design: Prospective cohort analysis of data obtained between baseline and six-year parallel-group randomized trial (n = 155, aged 40-60 years old, with MetS and NAFLD). Participants were randomized into three nutritional and PA intervention groups: Conventional diet (CD); MedDiet-high meal frequency (MD-HMF); MedDiet-physical activity (MD-PA). (4) Methods: PA and fitness status were assessed using a validated Minnesota questionnaire, ALPHA-FIT test battery, accelerometers, and functional fitness score. Information related to age, gender, education level, marital status, socioeconomic status, smoking habit, and alcohol consumption were also obtained. (5) Results: The CD group had higher improvement in standing handgrip than the MD-HMF group. The MD-PA group did more modified push-up repetitions than the CD group. The MD-PA and CD groups showed higher sitting handgrip than the MD-HMF group. The MD-HMF group showed the highest decrease in aerobic capacity. The MD-PA group showed lower light intensity PA/day than the CD and MD-HMF groups. The MD-PA group showed higher moderate intensity PA than the CD and MD-HMF groups. The CD group reported more METs per day than the MD-HMF group. (6) Conclusions: Lifestyle six-month intervention with diet and regular PA improved functional fitness in middle-aged patients with NAFLD and MetS. Aerobic capacity improved in patients who followed a Mediterranean diet and regular training sessions at six months.

Reference equations of oxygen uptake for the step test in the obese population

The aim of this study was to establish reference equations for the six-minute step test (6MST) based on demographic, anthropometric, body composition, and performance variables able to predict oxygen uptake (V̇O₂) in obese individuals. Seventy-three obese adults (42±14 years old, body mass index >30 kg/m²) from both sexes were included. They underwent anamnesis, body composition evaluation, and the 6MST with expired gases registered simultaneously. Three equations were developed for the obese population (n=73; 59% female). The first equation was composed of the up-and-down step cycles (UDS), sex, and age as predictors; the second equation was composed of the UDS, age, and lean mass (LM). Both equations collectively explained 68.1% of the V̇O₂ variance in the 6MST, while the third equation, composed of the UDS, age, and body mass, accounted for 67.7% of the V̇O₂ variance. UDS, sex, age, LM, and body mass were important V̇O₂ predictors of 6MST in these obese individuals. This study contributes to the dissemination of a simple, inexpensive, and fast evaluation method that can provide important indicators of cardiorespiratory fitness and guide strategies for rehabilitation.

Inspiratory Muscle Training Enhances Recovery Post COVID-19: A Randomised Controlled Trial

Background

Many people recovering from coronavirus disease 2019 (COVID-19) experience prolonged symptoms, particularly breathlessness. We urgently need to identify safe and effective COVID-19 rehabilitative strategies. The aim of the current study was to investigate the potential rehabilitative role of inspiratory muscle training (IMT).

Methods

281 adults (age 46.6±12.2 years; 88% female) recovering from self-reported COVID-19 (9.0±4.2 months post-acute infection) were randomised 4:1 to an 8-week IMT or a “usual care” waitlist control arm. Health-related quality-of-life and breathlessness questionnaires (King's Brief Interstitial Lung Disease (K-BILD) and Transition Dyspnoea Index (TDI)), respiratory muscle strength, and fitness (Chester Step Test) were assessed pre- and post-intervention. The primary end-point was K-BILD total score, with the K-BILD domains and TDI being key secondary outcomes.

Results

According to intention to treat, there was no difference between groups in K-BILD total score post-intervention (control: 59.5±12.4; IMT: 58.2±12.3; p<0.05) but IMT elicited clinically meaningful improvements in the K-BILD domains for breathlessness (control: 59.8±12.6; IMT: 62.2±16.2; p<0.05) and chest symptoms (control: 59.2±18.7; IMT: 64.5±18.2; p<0.05), along with clinically meaningful improvements in breathlessness according to TDI (control: 0.9±1.7 versus 2.0±2.0; p<0.05). IMT also improved respiratory muscle strength and estimated aerobic fitness.

Conclusions

IMT may represent an important home-based rehabilitation strategy for wider implementation as part of COVID-19 rehabilitative strategies. Given the diverse nature of long COVID, further research is warranted on the individual responses to rehabilitation; the withdrawal rate herein highlights that no one strategy is likely to be appropriate for all.

IMT can significantly improve breathlessness and respiratory muscle function in people with long COVID, and represents an effective, home-based rehabilitation strategy that could be widely implemented as part of COVID-19 recovery strategieshttps://bit.ly/3HiEyz0

A Comparison of the Validity of Three Exercise Tests for Estimating Maximal Oxygen Uptake in Korean Adults Aged 19–64 Years

The purpose of this study was to compare the validity of three submaximal exercise tests (SMETs) and develop practical predictive models for the VO2max in Korean adults. A total of 541 (287 males and 254 females) adults participated in this study. Their ages ranged from 19 to 64. The VO2max was measured using the maximal-graded exercise treadmill test. The SMETs were performed by a treadmill test, the YMCA step test, and the PACER test. Regression analysis was conducted to compare the validity of the VO2max predictive equations using SMETs. The validity of the predictive models was evaluated using explanatory power, standard error of estimate (SEE), and Bland-Altman analysis. The explanatory power between the measured VO2max and the predicted VO2max was 58.0% (<0.001), 59.2% (<0.001), and 71.7% (<0.001), respectively. The SEEs were 4.545, 4.478, and 3.732 (mL/kg/min). The models were significant predictors of VO2max and had acceptable validity in a large sample of Korean adults. Especially, among the predictive models, PACER had the highest acceptable effectiveness. Therefore, the equations developed in this study are recommended to better evaluate the cardiovascular endurance of Korean adults.

Validity of Estimating the Maximal Oxygen Consumption by Consumer Wearables: A Systematic Review with Meta-analysis and Expert Statement of the INTERLIVE Network

Background

Technological advances have recently made possible the estimation of maximal oxygen consumption (VO_2max) by consumer wearables. However, the validity of such estimations has not been systematically summarized using meta-analytic methods and there are no standards guiding the validation protocols.

Objective

The aim was to (1) quantitatively summarize previous studies investigating the validity of the VO_2max estimated by consumer wearables and (2) provide best-practice recommendations for future validation studies.

Methods

First, we conducted a systematic review and meta-analysis of studies validating the estimation of VO_2max by wearables. Second, based on the state of knowledge (derived from the systematic review) combined with the expert discussion between the members of the Towards Intelligent Health and Well-Being Network of Physical Activity Assessment (INTERLIVE) consortium, we provided a set of best-practice recommendations for validation protocols.

Results

Fourteen validation studies were included in the systematic review and meta-analysis. Meta-analysis results revealed that wearables using resting condition information in their algorithms significantly overestimated VO_2max (bias 2.17 ml·kg⁻¹·min⁻¹; limits of agreement − 13.07 to 17.41 ml·kg⁻¹·min⁻¹), while devices using exercise-based information in their algorithms showed a lower systematic and random error (bias − 0.09 ml·kg⁻¹·min⁻¹; limits of agreement − 9.92 to 9.74 ml·kg⁻¹·min⁻¹). The INTERLIVE consortium proposed six key domains to be considered for validating wearable devices estimating VO_2max, concerning the following: the target population, reference standard, index measure, testing conditions, data processing, and statistical analysis.

Conclusions

Our meta-analysis suggests that the estimations of VO_2max by wearables that use exercise-based algorithms provide higher accuracy than those based on resting conditions. The exercise-based estimation seems to be optimal for measuring VO_2max at the population level, yet the estimation error at the individual level is large, and, therefore, for sport/clinical purposes these methods still need improvement. The INTERLIVE network hereby provides best-practice recommendations to be used in future protocols to move towards a more accurate, transparent and comparable validation of VO_2max derived from wearables.

PROSPERO ID

CRD42021246192.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-021-01639-y.

Lessons learned from a pilot implementation of physical activity recommendations in axial spondyloarthritis exercise group therapy

Background

The Ankylosing Spondylitis Association of Switzerland (SVMB) aimed to implement physical activity recommendations (PAR) within their exercise groups (EGs). The PAR promote exercise in all fitness dimensions at the correct dose. To implement the PAR within EGs, they were translated into a new EG concept with five key activities: (a) training for supervising physiotherapists (PTs), (b) correctly dosed exercises in all fitness dimensions, (c) exercise counselling, (d) bi-annual fitness assessments, and (e) individual exercise training, in addition to EG. All these activities were realized in close coordination with SVMB management.

Objectives

To analyse the implementation success by evaluating adherence/fidelity, feasibility, and satisfaction at the patient, PTs, and organisational level.

Methods

The five key activities of the new EG concept were developed, executed, and assessed after 6 months. The primary outcomes for implementation success were adherence of patients to the recommended exercise behaviour, self-reported by electronic diary; fidelity of PTs to the new concept, self-reported by diary; SVMB organisational changes. Secondary outcomes were feasibility and satisfaction with the new EG concept at all three levels. The tertiary outcome, to evaluate the effectiveness of PAR, was patient fitness, assessed through fitness assessments.

Results

30 patients with axSpA (ten women, mean age 58 ± 9 years) and four PTs (three women, mean age 46 ± 9 years) participated. The patients' self-reporting of adherence to the PAR was insufficient (43%), possibly due to technical problems with the electronic dairy. The PTs' fidelity to the new EG concept was satisfactory. On all levels, the new concept was generally perceived as feasible and useful for supporting personalised exercise.The frequency of exercise counselling and the fitness assessments was found by patients and PTs to be too high and rigid. Patients' cardiorespiratory fitness [ES 1.21 (95%CI 0.59, 1.89)] and core strength [ES 0.61 (95%CI 0.18, 1.06)] improved over the 6 months.

Conclusions

The pilot implementation of PAR showed acceptance and satisfaction to be sufficient, thus confirming the need for evidence-based EGs, provided by a patient organisation in order to support active PA behaviour. However, adaptations are necessary to increase its feasibility for nationwide implementation.

Trial Registration: SNCTP, SNCTP000002880. Registered 31 May 2018, https://www.kofam.ch/en/snctp-portal/search/0/study/42491.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41927-021-00233-z.

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.

Enhanced recognition of emotional images is not affected by post-exposure exercise-induced arousal

Research suggests that aerobic exercise (i.e., exercise aiming to improve cardiovascular fitness) promotes cognition, but the impact on memory specifically, is unclear. There is some evidence to suggest that as little as one session of post-learning exercise benefits memory consolidation. Furthermore, memory may be particularly facilitated by exercise when the individual is emotionally aroused while encoding stimuli. The current study tested whether exercise after exposure to neutral and emotional images improved memory consolidation of the items among university students. Ninety-nine students were randomly instructed to either exercise or not exercise after viewing a set of images that were positive, neutral, and negative in valence, and they were later tested on their memory. Although emotional images were remembered better than non-emotional images, the results suggested that exercise did not influence this effect or enhance consolidation of the items overall. Explanations and implications for these findings are discussed.

Immersive Virtual Reality Influences Physiologic Responses to Submaximal Exercise: A Randomized, Crossover Trial

Objectives: This cross-sectional, randomly assigned study aimed to assess the influence of immersive virtual reality (VR) on exercise tolerance expressed as the duration of a submaximal exercise test (ET) on a cycle ergometer. Methods: The study enrolled 70 healthy volunteers aged 22-25years. Each participant performed an ET with and without VR. Time- and frequency-domain heart rate variability (HRV) parameters were analyzed for the first 3min (T1), the last 3min (T2), and the time at which the shorter of the two tests terminated (Tiso). In the time domain, a SD of R-R intervals (SDNN) and a root mean square of successive R-R interval differences (RMSSD) in milliseconds were computed. The following spectral components were considered: low frequency (LF), high frequency (HF), total power (TP), and LF/HF ratio. The study was registered in ClinicalTrials.gov (NCT04197024). Results: Compared to standard ET, tests in immersive VR lasted significantly longer (694 vs. 591s, p<0.00001) and were associated with lower HR response across the range of corresponding exercise levels, averaging 5-8 beats/min. In the multiple regression analysis, the ET duration was positively determined by male sex, immersion in VR, and negatively determined by HRT1 and RMSSDT1. Conclusion: Exercising in VR is associated with lower HR which allowed subjects to exercise for a longer time before reaching target heart rate (HR). In addition, the increase in exercise duration was found to be related to an adjustment in autonomic nervous activity at a given work rate favoring parasympathetic predominance.

Temporal trends in step test performance for Chinese adults between 2000 and 2014

BACKGROUD/OBJECTIVE

Cardiorespiratory endurance is an excellent marker of functional endurance and health among adults. The aim of this study was to estimate temporal trends in step test performance for Chinese adults between 2000 and 2014.

METHODS

Apparently healthy adults aged 20-59 years were included. Nationally representative step test data (n = 603,977) from 2000, 2005, 2010, and 2014 were reported descriptively by the China Physical Fitness Surveillance Center. Temporal trends in means were estimated at the sex-age level for all adults and separate location/occupation groups using sample-weighted linear regression, with trends in distributional characteristics described visually and estimated as the ratio of coefficients of variation (CVs).

RESULTS

Collectively, there was a negligible improvement in mean step test performance of 0.12 standardized effect sizes (95% confidence interval (95%CI): 0.11-0.13). Negligible to small improvements were observed for all age, sex, location, and occupation groups. Variability declined substantially over time (ratio of CVs (95%CI): 0.86 (0.86-0.86)), with negligible to large improvements in those below the 10th percentile, and negligible to moderate declines in those above the 90th percentile.

CONCLUSION

There have been negligible to large improvements in step test performance for low to average performing Chinese adults since 2000, which may be meaningful to public health because low endurance is an important risk factor for all-cause mortality.

Women's Lives Matter-The Critical Need for Women to Prioritize Optimal Physical Activity to Reduce COVID-19 Illness Risk and Severity

Physical activity (PA) is beneficial for the health and wellness of individuals and societies. During an infectious disease pandemic, such as the one caused by COVID-19, social distancing, quarantines, and lockdowns are used to reduce community spread of the disease. Unfortunately, such nonpharmacological interventions or physical risk mitigation measures also make it challenging to engage in PA. Reduced PA could then trigger physiological changes that affect both mental and physical health. In this regard, women are more likely to experience physical and psychological distress. PA is a safe and effective nonpharmacological modality that can help prevent and manage several mental and physical health problems when performed correctly. PA might even confer benefits that are directly related to decreasing COVID-19 morbidity and mortality in women. In this review, we summarize why optimal PA must be a priority for women during the COVID-19 pandemic. We then discuss chronic COVID-19 illness and its impact on women, which further underscores the need for worldwide preventive health strategies that include PA. Finally, we discuss the importance of vaccination against COVID-19 for women, as part of prioritizing preventive healthcare and an active lifestyle.

Criterion-Related Validity of Field-Based Fitness Tests in Adults: A Systematic Review

We comprehensively assessed the criterion-related validity of existing field-based fitness tests used to indicate adult health (19–64 years, with no known pathologies). The medical electronic databases MEDLINE (via PubMed) and Web of Science (all databases) were screened for studies published up to July 2020. Each original study’s methodological quality was classified as high, low and very low, according to the number of participants, the description of the study population, statistical analysis and systematic reviews which were appraised via the AMSTAR rating scale. Three evidence levels were constructed (strong, moderate and limited evidence) according to the number of studies and the consistency of the findings. We identified 101 original studies (50 of high quality) and five systematic reviews examining the criterion-related validity of field-based fitness tests in adults. Strong evidence indicated that the 20 m shuttle run, 1.5-mile, 12 min run/walk, YMCA step, 2 km walk and 6 min walk test are valid for estimating cardiorespiratory fitness; the handgrip strength test is valid for assessing hand maximal isometric strength; and the Biering–Sørensen test to evaluate the endurance strength of hip and back muscles; however, the sit-and reach test, and its different versions, and the toe-to-touch test are not valid for assessing hamstring and lower back flexibility. We found moderate evidence supporting that the 20 m square shuttle run test is a valid test for estimating cardiorespiratory fitness. Other field-based fitness tests presented limited evidence, mainly due to few studies. We developed an evidence-based proposal of the most valid field-based fitness tests in healthy adults aged 19–64 years old.

Primary Care and Physical Literacy: A Non-Randomized Controlled Pilot Study to Combat the High Prevalence of Physically Inactive Adults in Austria

The multidimensional concept of physical literacy is fundamental for lifelong physical activity engagement. However, physical literacy-based interventions are in their infancy, especially among adults. Therefore, the purpose of this pilot study was to assess the association of a physical literacy-based intervention with changes in self-reported physical literacy among inactive adults. A non-randomized controlled study (2 × 2 design) was conducted, comparing pre- vs. postintervention. Twenty-eight inactive healthy participants in the intervention group (89% female, 53 ± 10 years) entered a physical literacy-based intervention once weekly for 14 weeks. The non-treated control group consisted of 22 inactive adults (96% female, 50 ± 11 years). Physical literacy was evaluated with a questionnaire encompassing five domains: physical activity behavior, attitude/understanding, motivation, knowledge, and self-efficacy/confidence. ANOVA models were applied to evaluate changes by time and condition. Following the intervention, significant improvements were seen for overall physical literacy and in four out of five physical literacy domains, including physical activity behavior, attitude/understanding, knowledge, and self-efficacy/confidence (all p < 0.01, Cohen's d = 0.38-0.83). No changes by time x condition were found for motivation. The physical literacy-based intervention applied in this study may be a promising approach to help inactive adults to adopt an active lifestyle.

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.