Walking cadence (steps/min) and intensity in 21-40 year olds: CADENCE-adults

Changes in Accelerometer-Measured Physical Activity and Sedentary Time Across Retirement Transition as a Predictor of Self-Rated Health

BACKGROUND

Retirement transition has been shown to associate with changes in physical activity (PA) and self-rated health (SRH), but their interrelationship is less studied. The aim was to investigate changes in accelerometer-measured total PA, moderate to vigorous PA (MVPA), and sedentary time across retirement transition as a predictor of SRH.

METHODS

Data from the Swedish Retirement Study and the Finnish Retirement and Aging study were harmonized and pooled. Data from 3 waves (about 12 mo apart) were included: 1 preretirement (wave 1) and 2 postretirement follow-ups (wave 2-3). A totally of 245 participants (27% men) were included. Thigh-worn accelerometers were used to collect data for PA variables (wave 1-2), and SRH was obtained from the questionnaire (wave 1-3).

RESULTS

Between wave 1 and 2, total PA decreased with 11 (CI, -22 to -1) minutes per day, MVPA was stable (0 [CI, -3 to 3] min), and sedentary time decreased nonsignificantly with 9 (CI, -20 to 1) minutes. SRH changed between all 3 waves (all P < .001). At preretirement, 10 more minutes of MVPA was associated with greater odds of better SRH when adjusting for accelerometer wear-time, cohort, sex, age, and occupational status (odds ratio: 1.11 [95% CI, 1.02-1.22]). This association was no longer statistically significant when additionally adjusting for marital status, body mass index, and smoking. No significant associations were observed between changes in the PA variables during retirement transition and SRH at postretirement follow-ups.

CONCLUSIONS

This study showed a cross-sectional association between MVPA and greater odds of reporting better SRH before retirement. No longitudinal associations were observed between changes in the PA variables from before to after retirement and later changes in SRH.

Is dog walking suitable for physical activity promotion? Investigating the exercise intensity of on-leash dog walking

Background

Approximately a quarter of the global population is physically inactive, increasing the prevalence of chronic health conditions such as cardiovascular disease. Clearly, a population shift is needed to increase physical activity participation. Given almost half of American and Australian households have at least one dog, dog walking has the potential to increase physical activity. The objective of this study was to characterize the exercise intensity of dog walking using physiological measures to determine whether it achieved a threshold for health-enhancement.

Method

From February 2020 to September 2022, dog owners (aged > 18 years, without impediment to walking) who resided in metropolitan Sydney participated in an on-leash dog walk for a minimum of 20 minutes, while wearing a heart rate monitor and carrying a phone to track cadence, route and duration.

Results

Forty-three participants were recruited (aged 34.26 ± 16 years). Data from measures of %heart rate reserve (38 ± 10.8 %HRR), %heart rate max (61 ± 7.2 %HRmax) and average cadence (45 ± 8.4steps/min) classified dog-walking as light intensity. However, when using average walking speed (4.29 ± 0.8 km/hr) and metabolic equivalents (3.53 ± 0.6METs), the walk was classified as moderate intensity.

Conclusion

Overall, depending on the intensity measure used, dog walking was positioned in the upper range of light intensity and the lower range of moderate intensity. Although dog walking at a certain intensity may be difficult to prescribe as strategy for meeting current moderate-to-vigorous focused physical activity recommendations, it should be recognised as a beneficial activity that may reach moderate intensity on some occasions.

Agreement between the activPAL accelerometer and direct observation during a series of gait and sit-to-stand tasks in people living with cervical dystonia

Background

Accelerometers are commonly used for the assessment of PA; however, these devices have not been validated in people with dystonia who experience movement limitations. To properly understand movement behaviors and deliver accurate exercise prescription in this population, the validity of these devices must be tested.

Objective

This study aimed to validate step count and postural transitions detected by the activPAL accelerometer (AP) against direct observation (DO) during two functional assessments: the 30-s sit-to-stand (30STS) and 6-min usual-pace walk tests. Methods: A total of 11 participants with cervical dystonia (CD) (male/female n = 5/6; mean age = 61 years; BMI = 24 kg/m2) performed the 6-min usual pace walking and 30STS while wearing the activPAL. A trained observer counted steps and observed the number of sit-to-stands.

Results

The average step count detected with AP and DO was 651.8 (218-758) and 654.5 (287-798) respectively. The average transitions detected were 11 (4-16) and 12 (4-17) respectively. Both methods showed good agreement and there was a statistically significant and strong correlation between the two methods, i.e., transitions (r = 0.983, p = 0.0001), and step counts (r = 0.9841, p = 0.0001).

Conclusion

There is a good agreement between activPAL and direct observation for step counts and transitions between sitting and standing in people living with CD.

The Effectiveness and Perceptions of Three Moderate Intensity Walking Cadence Aids and their Effects on Affective States: A Mixed Methods Study

Substantial health benefits can be derived from walking at a moderate intensity cadence. To help regulate this cadence, three distinct aids exist 1) self-perception; 2) cadence prescription; 3) auditory cues. This study aimed to compare the effectiveness and explore perceptions of these aids to promote moderate intensity walking and effects on affective states, thereby addressing an important research gap. Individualised moderate relative intensity waking cadence was determined for participants (n = 23, Mage = 26.35, SD = 10.11). A convergent mixed-methods design was employed. A within-persons repeated measures design was used to explore the effectiveness of three aids (general guidelines, cadence prescription, and music) on promoting moderate intensity physical activity and positive affective states. Perceptions of these aids were elicited through qualitative interviews and thematic content analysis. Main effects for condition on relative physical activity intensity (η2 = .72) and positive affect (η2 = .25) were observed. Music evoked significantly higher relative physical activity intensity than other conditions (p values < .01), and higher positive affect compared to the general guidelines condition (p = .038). A significantly greater proportion of participants achieved moderate relative intensity physical activity during the music compared to general guidelines condition (p = .03). Congruently, qualitative findings suggested that participants predominantly perceived music as most effective for promoting a moderate intensity cadence and positive affect. However, individual variability existed in ability to utilise this aid. Implications of the findings for practitioners seeking to promote a moderate intensity cadence and positive affect during walking are discussed.

Life-course social participation and physical activity in midlife: longitudinal associations in the 1970 British Cohort Study (BCS70)

A hypothesized benefit of social participation is that it encourages people to be more physically active. However, limited evidence exists on the association between social participation over the life-course and physical activity in midlife. We sought to apply a life-course framework to examine the association of social participation and device measured physical activity in midlife in the UK. We used the 1970 British Birth Cohort Study (BCS70), which includes all people born in Britain during a single week in 1970. Social participation was assessed at ages 16, 30, 34 and 42. Physical activity was measured by accelerometery at age 46, as mean daily step count and time spent in moderate to vigorous physical activity (MVPA). The associations of social participation and physical activity were tested using two different life-course models: the sensitive period model and the accumulation model. Individuals with medium and high participation compared to no social participation over their life-course had higher mean daily step count and MVPA in midlife, supporting the accumulation model. In the sensitive period model, only those that actively participated at age 42 had higher mean daily steps and MVPA compared to those who did not participate. Our study provides empirical evidence on the importance of sustaining social participation at all ages over the life-course rather than at a particular timepoint of someone's life. If our findings reflect causal effects, interventions to promote social participation throughout the life-course could be an avenue to promote physical activity in middle life.

The feasibility and acceptability of an app-based intervention with brief behavioural support (APPROACH) to promote brisk walking in people diagnosed with breast, prostate and colorectal cancer in the UK

INTRODUCTION

Increased moderate to vigorous physical activity (MVPA) can improve clinical and psychosocial outcomes for people living with and beyond cancer (LWBC). This study aimed to assess the feasibility and acceptability of trial procedures in a pilot randomised controlled trial (RCT) of a theory-driven app-based intervention with behavioural support focused on promoting brisk walking (a form of MVPA) in people LWBC (APPROACH).

METHODS

Participants diagnosed with breast, prostate or colorectal cancer were recruited from a single UK hospital site. Assessments at baseline and 3 months included online questionnaires, device-measured brisk walking (activPAL accelerometer) and self-reported weight and height. Participants were randomised to intervention or control (care as usual). The intervention comprised a non-cancer-specific app to promote brisk walking (National Health Service 'Active 10') augmented with print information about habit formation, a walking planner and two behavioural support telephone calls. Feasibility and acceptability of trial procedures were explored. Initial estimates for physical activity informed a power calculation for a phase III RCT. A preliminary health economics analysis was conducted.

RESULTS

Of those medically eligible, 369/577 (64%) were willing to answer further eligibility questions and 90/148 (61%) of those eligible were enrolled. Feasibility outcomes, including retention (97%), assessment completion rates (>86%) and app download rates in the intervention group (96%), suggest that the trial procedures are acceptable and that the intervention is feasible. The phase III RCT will require 472 participants to be randomised. As expected, the preliminary health economic analyses indicate a high level of uncertainty around the cost-effectiveness of the intervention.

CONCLUSIONS

This pilot study demonstrates that a large trial of the brisk walking intervention with behavioural support is both feasible and acceptable to people LWBC. The results support progression onto a confirmatory phase III trial to determine the efficacy and cost-effectiveness of the intervention.

Device-measured physical activity and cardiometabolic health: the Prospective Physical Activity, Sitting, and Sleep (ProPASS) consortium

BACKGROUND AND AIMS

Physical inactivity, sedentary behaviour (SB), and inadequate sleep are key behavioural risk factors of cardiometabolic diseases. Each behaviour is mainly considered in isolation, despite clear behavioural and biological interdependencies. The aim of this study was to investigate associations of five-part movement compositions with adiposity and cardiometabolic biomarkers.

METHODS

Cross-sectional data from six studies (n = 15 253 participants; five countries) from the Prospective Physical Activity, Sitting and Sleep consortium were analysed. Device-measured time spent in sleep, SB, standing, light-intensity physical activity (LIPA), and moderate-vigorous physical activity (MVPA) made up the composition. Outcomes included body mass index (BMI), waist circumference, HDL cholesterol, total:HDL cholesterol ratio, triglycerides, and glycated haemoglobin (HbA1c). Compositional linear regression examined associations between compositions and outcomes, including modelling time reallocation between behaviours.

RESULTS

The average daily composition of the sample (age: 53.7 ± 9.7 years; 54.7% female) was 7.7 h sleeping, 10.4 h sedentary, 3.1 h standing, 1.5 h LIPA, and 1.3 h MVPA. A greater MVPA proportion and smaller SB proportion were associated with better outcomes. Reallocating time from SB, standing, LIPA, or sleep into MVPA resulted in better scores across all outcomes. For example, replacing 30 min of SB, sleep, standing, or LIPA with MVPA was associated with -0.63 (95% confidence interval -0.48, -0.79), -0.43 (-0.25, -0.59), -0.40 (-0.25, -0.56), and -0.15 (0.05, -0.34) kg/m2 lower BMI, respectively. Greater relative standing time was beneficial, whereas sleep had a detrimental association when replacing LIPA/MVPA and positive association when replacing SB. The minimal displacement of any behaviour into MVPA for improved cardiometabolic health ranged from 3.8 (HbA1c) to 12.7 (triglycerides) min/day.

CONCLUSIONS

Compositional data analyses revealed a distinct hierarchy of behaviours. Moderate-vigorous physical activity demonstrated the strongest, most time-efficient protective associations with cardiometabolic outcomes. Theoretical benefits from reallocating SB into sleep, standing, or LIPA required substantial changes in daily activity.

College Students' Day-to-Day Maladaptive Drinking Responses to Stress Severity and Stressor-Related Guilt and Anger

BACKGROUND

Stress is a common part of college students' daily lives that may influence their physical activity (PA) and alcohol use. Understanding features of daily stress processes that predict health behaviors could help identify targets for just-in-time interventions.

PURPOSE

This study used intensive longitudinal data to examine whether prior day stress processes predict current day PA or alcohol use.

METHODS

Participants (N=58, Mage=20.5, 59% women, 70% White) were 18-to-25-year-old students who engaged in binge drinking at least twice monthly and used cannabis or tobacco in the past year. They wore activity (activPAL4) and alcohol (Secure Continuous Remote Alcohol Monitor) monitors for 11 days to assess daily PA (e.g., step counts) and alcohol use (e.g., drinking day), and completed daily surveys about yesterday's stress, including number of stressors (i.e., frequency), stressor intensity (i.e., severity), and frequency of affective states (e.g., guilt). Multilevel models examined prior day stress predicting current day PA or alcohol use.

RESULTS

Participants had higher odds of current day drinking (odds ratio=1.21) and greater area under the curve (B=0.08) when they experienced greater than usual stress severity the prior day. Participants had higher current day peak transdermal alcohol concentration (B=0.12) and area under the curve (B=0.11) when they more frequently experienced guilt due to stressors the prior day.

CONCLUSIONS

College students' unhealthy response of increasing alcohol use due to stress could adversely impact health outcomes. There is a critical need for interventions addressing students' ability to effectively manage and respond to the stress-inducing, daily demands of student life.

Cadence (steps/min) and relative intensity in 61 to 85-year-olds: the CADENCE-Adults study

BACKGROUND

We previously demonstrated that a heuristic (i.e., evidence-based, rounded yet practical) cadence threshold of ≥ 100 steps/min was associated with absolutely-defined moderate intensity physical activity (i.e., ≥ 3 metabolic equivalents [METs]) in older adults 61-85 years of age. Although it was difficult to ascertain achievement of absolutely-defined vigorous (6 METs) intensity, ≥ 130 steps/min was identified as a defensible threshold for this population. However, little evidence exists regarding cadence thresholds and relatively-defined moderate intensity indicators, including ≥ 64% heart rate [HR] maximum [HRmax = 220-age], ≥ 40% HR reserve [HRR = HRmax-HRresting], and ≥ 12 Borg Scale Rating of Perceived Exertion [RPE]; or vigorous intensity indicators including ≥ 77%HRmax, ≥ 60%HRR, and ≥ 14 RPE.

PURPOSE

To analyze the relationship between cadence and relatively-defined physical activity intensity and identify relatively-defined moderate and vigorous heuristic cadence thresholds for older adults 61-85 years of age.

METHODS

Ninety-seven ostensibly healthy adults (72.7 ± 6.9 years; 49.5% women) completed up to nine 5-min treadmill walking bouts beginning at 0.5 mph (0.8 km/h) and progressing by 0.5 mph speed increments (with 2-min rest between bouts). Directly-observed (and video-recorded) steps were hand-counted, HR was measured using a chest-strapped monitor, and in the final minute of each bout, participants self-reported RPE. Segmented mixed model regression and Receiver Operating Characteristic (ROC) curve analyses identified optimal cadence thresholds associated with relatively-defined moderate (≥ 64%HRmax, ≥ 40%HRR, and ≥ 12 RPE) and vigorous (≥ 77%HRmax, ≥ 60%HRR, and ≥ 14 RPE) intensities. A compromise between the two analytical methods, including Youden's Index (a sum of sensitivity and specificity), positive and negative predictive values, and overall accuracy, yielded final heuristic cadences.

RESULTS

Across all relatively-defined moderate intensity indicators, segmented regression models and ROC curve analyses identified optimal cadence thresholds ranging from 105.9 to 112.8 steps/min and 102.0-104.3 steps/min, respectively. Comparable values for vigorous intensity indicators ranged between126.1-132.1 steps/min and 106.7-116.0 steps/min, respectively. Regardless of the relatively-defined intensity indicator, the overall best heuristic cadence threshold aligned with moderate intensity was ≥ 105 steps/min. Vigorous intensity varied between ≥ 115 (greater sensitivity) or ≥ 120 (greater specificity) steps/min.

CONCLUSIONS

Heuristic cadence thresholds align with relatively-defined intensity indicators and can be useful for studying and prescribing older adults' physiological response to, and/or perceived experience of, ambulatory physical activity.

TRIAL REGISTRATION

Clinicaltrials.gov NCT02650258. Registered 24 December 2015.

Traditional lifestyle factors partly mediate the association of socioeconomic position with intrahepatic lipid content: The Maastricht study

Background & Aims

Recent studies have unveiled an association between socioeconomic position (SEP) and intrahepatic lipid (IHL) content. The aim of this study was to examine to what extent traditional lifestyle factors mediate the relationship between SEP and IHL content, independent of aetiology, and non-alcoholic fatty liver disease (NAFLD).

Methods

We used cross-sectional data derived from The Maastricht Study (N = 4,001; mean age: 60 years, 49% women, 32% low education level, 21% diabetes, 21% NAFLD). Education, income, and occupation were used as indicators of SEP. Physical activity (accelerometer), intake of total energy, alcohol, saturated fat, protein, vitamin E, dietary fibre, and fructose from sugar-sweetened beverages (SSBs) and fruit juice (food frequency questionnaires) were potential mediators. IHL content was quantified by magnetic resonance imaging. Age, sex, and type 2 diabetes were covariates. Multiple parallel mediation analyses (bootstraps = 10,000) were performed.

Results

Individuals with a low education level had a 1.056-fold higher IHL content (95% CI: 1.03-1.08) and a 44% greater NAFLD risk (OR:1.44; 95% CI:1.18-1.77) compared with those with higher education levels. Approximately 8.9% of educational disparity in risk of IHL content was attributable to moderate-to-vigorous physical activity; 6.3% to fructose intake from SSBs; 5.5% to dietary fibre; and -23% to alcohol. Approximately 8.7% of educational disparity in risk of NAFLD was attributable to moderate-to-vigorous physical activity; and 7.7% to fructose intake from SSBs. However, the indirect effect of these mediators was small (0.998 for IHL content and 1.045 for NAFLD) in comparison to the total effect. Similar results were found when income and occupation were used as SEP indicators.

Conclusions

Societal measures may alleviate the burden of NAFLD and further studies that identify mediators other than traditional lifestyle factors are warranted to define the relationship underlying SEP and IHL content.

Impact and implications

Individuals with a low or medium level of education, income, or occupational status had more fat accumulation in their livers than individuals with a higher education, income, or occupational status. This difference may be attributed to the influence of unhealthy lifestyle factors, such as reduced physical activity and a higher intake of sugar-sweetened beverages among individuals with lower socioeconomic position. Nevertheless, other yet unknown factors may also play a role.

Relationship of Daily Step Counts to All-Cause Mortality and Cardiovascular Events

BACKGROUND

The minimal and optimal daily step counts for health improvements remain unclear.

OBJECTIVES

A meta-analysis was performed to quantify dose-response associations of objectively measured step count metrics in the general population.

METHODS

Electronic databases were searched from inception to October 2022. Primary outcomes included all-cause mortality and incident cardiovascular disease (CVD). Study results were analyzed using generalized least squares and random-effects models.

RESULTS

In total, 111,309 individuals from 12 studies were included. Significant risk reductions were observed at 2,517 steps/d for all-cause mortality (adjusted HR [aHR]: 0.92; 95% CI: 0.84-0.999) and 2,735 steps/d for incident CVD (aHR: 0.89; 95% CI: 0.79-0.999) compared with 2,000 steps/d (reference). Additional steps resulted in nonlinear risk reductions of all-cause mortality and incident CVD with an optimal dose at 8,763 (aHR: 0.40; 95% CI: 0.38-0.43) and 7,126 steps/d (aHR: 0.49; 95% CI: 0.45-0.55), respectively. Increments from a low to an intermediate or a high cadence were independently associated with risk reductions of all-cause mortality. Sex did not influence the dose-response associations, but after stratification for assessment device and wear location, pronounced risk reductions were observed for hip-worn accelerometers compared with pedometers and wrist-worn accelerometers.

CONCLUSIONS

As few as about 2,600 and about 2,800 steps/d yield significant mortality and CVD benefits, with progressive risk reductions up to about 8,800 and about 7,200 steps/d, respectively. Additional mortality benefits were found at a moderate to high vs a low step cadence. These findings can extend contemporary physical activity prescriptions given the easy-to-understand concept of step count. (Dose-Response Relationship Between Daily Step Count and Health Outcomes: A Systematic Review and Meta-Analyses; CRD42021244747).

Modifications of 24-h movement behaviors to prevent obesity in retirement: a natural experiment using compositional data analysis

BACKGROUND

Retirement often leads to a more passive lifestyle and may therefore lead to weight gain. This study aims to investigate longitudinal associations between changes in 24-h movement behaviors and BMI and waist circumference in relation to the transition from work to retirement.

METHODS

The study population included 213 retiring public sector workers (mean age 63.5 years, standard deviation 1.1) from the Finnish Retirement and Aging study. Before and after retirement participants wore an Axivity accelerometer on their thigh and filled in a daily log for at least four days to measure daily time spent sleeping, in sedentary behavior (SED), light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA). Also, their body mass index (BMI) and waist circumference were measured repeatedly. Compositional linear regression analysis and isotemporal substitution analysis were used to study associations between one-year changes in 24-h movement behaviors and concurrent changes in BMI and waist circumference.

RESULTS

An increase in MVPA in relation to sleep, SED and LPA was associated with a decreasing BMI (β = -0.60, p = 0.04) and waist circumference (β = -2.14, p = 0.05) over one year from before retirement to after retirement. In contrast, increasing sleep in relation to SED, LPA and MVPA was associated with an increasing BMI (β = 1.34, p = 0.02). Reallocating 60 min from MVPA to SED or sleep was estimated to increase BMI by on average 0.8-0.9 kg/m2 and waist circumference by 3.0 cm during one year.

CONCLUSIONS

During the transition from work to retirement, increasing MVPA was associated with a slight decrease in BMI and waist circumference, whereas increasing sleep was associated with an increasing BMI. Common life transitions, like retirement, should be considered when giving recommendations and guidance for physical activity and sleep.

A Low-Cost Instrumented Shoe System for Gait Phase Detection Based on Foot Plantar Pressure Data

This paper presents a novel low-cost and fully-portable instrumented shoe system for gait phase detection. The instrumented shoe consists of 174 independent sensing units constructed based on an off-the-shelf force-sensitive film known as the Velostat conductive copolymer. A zero potential method was implemented to address the crosstalk effect among the matrix-formed sensing arrays. A customized algorithm for gait event and phase detection was developed to estimate stance sub-phases including initial contact, flat foot, and push off. Experiments were carried out to evaluate the performance of the proposed instrumented shoe system in gait phase detection for both straight-line walking and turning walking. The results showed that the mean absolute time differences between the estimated phases by the proposed instrumented shoe system and the reference measurement ranged from 45 to 58 ms during straight-line walking and from 51 to 77 ms during turning walking, which were comparable to the state of art.Clinical and Translational Impact Statement-By allowing convenient gait monitoring in home healthcare settings, the proposed system enables extensive ADL data collection and facilitates developing effective treatment and rehabilitation strategies for patients with movement disorders.

Association between cognition and gait in multiple sclerosis: A smartphone-based longitudinal analysis

BACKGROUND

Gait and cognition impairments are common problems among People with Multiple Sclerosis (PwMS). Previous studies have investigated cross-sectional associations between gait and cognition. However, there is a lack of evidence regarding the longitudinal association between these factors in PwMS. Therefore, the objective of this study was to explore this longitudinal relationship using smartphone-based data from the Floodlight study.

METHODS

Using the publicly available Floodlight dataset, which contains smartphone-based longitudinal data, we used a linear mixed model to investigate the longitudinal relationship between cognition, measured by the Symbol Digit Modalities Test (SDMT), and gait, measured by the 2 Minute Walking test (2 MW) step count and Five-U-Turn Test (FUTT) turning speed. Four mixed models were fitted to explore the association between: 1) SDMT and mean step count; 2) SDMT and variability of step count; 3) SDMT and mean FUTT turning speed; and 4) SDMT and variability of FUTT turningt speed.

RESULTS

After controlling for age, sex, weight, and height, there were significant correlations between SDMT and the variability of 2 MW step count, the mean of FUTT turning speed. No significant correlation was observed between SDMT and the 2 MW mean step count.

SIGNIFICANCE

Our findings support the evidence that gait and cognition are associated in PwMS. This may support clinicians to adjust treatment and intervention programs that address both gait and cognitive impairments.

Cadence (steps/min) as an indicator of the walk-to-run transition

BACKGROUND

Humans naturally transition from walking to running at a point known as the walk-to-run transition (WRT). The WRT commonly occurs at a speed of ∼2.1 m/s (m/s) or a Froude number (dimensionless value considering leg length) of 0.5. Emerging evidence suggests the WRT can also be classified using a cadence of 140 steps/min. An accurate cadence-based WRT metric would aid in classifying wearable technology minute-level step metrics as walking vs. running.

PURPOSE

To evaluate performance of 1) WRT predictors directly identified from a treadmill-based dataset of sequentially faster bouts, and 2) accepted WRT predictors compiled from previous literature.

METHODS

Twenty-eight adults (71.4% men; age = 36.6 ± 12.8 years, BMI = 26.2 ± 4.7 kg/m2) completed a series of five-minute treadmill walking bouts increasing in 0.2 m/s increments until they freely chose to run. Optimal WRT values for speed, Froude number, and cadence were identified using receiver operating characteristic (ROC) curve analyses. WRT value performance was evaluated via classification accuracy metrics.

RESULTS

Overall accuracies (metric, percent) according to WRT predictors from previous literature were: speed (2.1 m/s, 55.0%), Froude number (0.5, 76.8%), and cadence (140 steps/min, 91.1%), and those from the dataset herein were: speed (1.9 and 2.0 m/s, 78.6%), Froude number (0.68, 77.3%), and cadence (134, 139, and 141 steps/min, 92.9%). The three equally accurate cadence values support a heuristic range of cadence-based WRT values in young and middle-aged adults: 135-140 steps/min.

SIGNIFICANCE

A tight range of cadence values performed better as WRT predictors compared to either previously reported or directly identified speed or Froude number values. These findings have important implications for gait classification, especially considering cadence is a simple metric which can be readily assessed across settings using direct observation or wearable technologies.

Physical activity virtual intervention for improving mental health among university students during the COVID-19 pandemic: A Co-creation process and evaluation using the Behavior Change Wheel

Background

During the COVID-19 pandemic, there were reductions in university students' physical activity, which further increased their mental distress, calling for technology-based physical activity interventions to address the challenges in delivering in-person interventions. This study aimed to develop a technology-based physical activity intervention and pilot test it.

Methods

We developed a virtually-delivered team-based physical activity challenge using the Behavior Change Wheel and Co-creation Framework based on Self-determination Theory. A pilot study was conducted in the evaluation phase to measure the recruitment rate, dropout rate, change in physical activity, and mental distress while identifying problems and collecting participants' opinions regarding the challenge. Wilcoxon signed-rank tests were conducted to assess the change in physical activity and mental distress. Qualitative data were analyzed using thematic analysis.

Results

A three-week physical activity challenge comprising five identified intervention functions was held with 480 participants. The recruitment rate was 84.8% resulting from 407 virtual challenge participants who were conveniently joined as research participants. The dropout rate for the pilot study was 10.96% resulting from the incompatibility problems with the application. Among sample participants who lacked physical activity, participation in this challenge improved their physical activity by 52.5 min of moderate-intensity physical activity per week and reduced their mental distress by three points of self-reporting questionnaire-20 score. Issues regarding the virtual application and the influence of participation in the challenge on basic psychological needs emerged. Participants' opinions identified lack of time as the main barrier to physical activity.

Conclusion

A co-created physical activity intervention developed using the Behavioral Change Wheel Framework inspired high interest from university students and may increase their physical activity and improve their mental health. Several suggestions were discussed to address the identified problems and improve the internal and external validity of the evaluation phase.

Trial registration

TCTR20220720004 (retrospectively registered on July 19, 2022).

Step-Based Metrics and Translations of Physical Activity Guidelines among Adults in the HCHS/SOL

PURPOSE

In a cross-sectional sample of US Hispanic/Latino adults, we aimed to describe step-based metric distributions, estimate their associations with activity counts and self-report, and calibrate step-based translations of current (2018) US physical activity (PA) guidelines, that is, ≥150 min·wk -1 moderate-to-vigorous PA (MVPA) from accelerometer counts and self-report.

METHODS

The Hispanic Community Health Study/Study of Latinos enrolled 16,415 Hispanic/Latino adults 18-74 yr from four US cities (2008-2011). Participants completed the Global PA Questionnaire and 1 wk of Actical accelerometer wear ( n = 12,528). Weighted medians were used to describe step-based metrics, and Spearman correlations estimated their relationships with count-based and self-reported PA indicators. Receiver operator characteristic curve analyses were used to examine the ability of each step-based metric to classify participants meeting PA guidelines.

RESULTS

Overall, US Hispanic/Latino adults accumulated medians of 6770 steps per day and 6, 18, 236, and 630 min·d -1 at ≥100, ≥70, 1-69, and 0 steps per minute, respectively. Count-based time in MVPA, light PA, and sedentary behavior were most strongly correlated ( rs = 0.79-0.85) with times ≥70, 1-69, and 0 steps per minute, respectively, whereas self-reported MVPA had similar correlations with steps per day and times ≥40 and ≥70 steps per minute ( rs = 0.28-0.29). Time ≥70 steps per minute had the greatest capacity to classify participants meeting PA guidelines with both measures of MVPA.

CONCLUSIONS

This study provides the first normative values (based on percentiles) of step-based metrics for US Hispanic/Latino adults, which can facilitate surveillance, program planning, research, and data interpretation. Our finding that PA guidelines corresponded to 6000-7000 steps per day or ~20 min·d -1 at ≥70 steps per minute with an Actical accelerometer can be considered alongside dose-response relationships with health outcomes to develop step-based recommendations that are consistent with and better communicate PA guidelines.

Frailty Syndrome as a Transition from Compensation to Decompensation: Application to the Biomechanical Regulation of Gait

Most gait parameters decrease with age and are even more importantly reduced with frailty. However, other gait parameters exhibit different or even opposite trends for aging and frailty, and the underlying reason is unclear. Literature focuses either on aging, or on frailty, and a comprehensive understanding of how biomechanical gait regulation evolves with aging and with frailty seems to be lacking. We monitored gait dynamics in young adults (19-29 years, n = 27, 59% women), middle-aged adults (30-59 years, n = 16, 62% women), and non-frail (>60 years, n = 15, 33% women) and frail older adults (>60 years, n = 31, 71% women) during a 160 m walking test using the triaxial accelerometer of the Zephyr Bioharness 3.0 device (Zephyr Technology, Annapolis, MD, USA). Frailty was evaluated using the Frail Scale (FS) and the Clinical Frailty Scale (CFS). We found that in non-frail older adults, certain gait parameters, such as cadence, were increased, whereas other parameters, such as step length, were decreased, and gait speed is maintained. Conversely, in frail older adults, all gait parameters, including gait speed, were decreased. Our interpretation is that non-frail older adults compensate for a decreased step length with an increased cadence to maintain a functional gait speed, whereas frail older adults decompensate and consequently walk with a characteristic decreased gait speed. We quantified compensation and decompensation on a continuous scale using ratios of the compensated parameter with respect to the corresponding compensating parameter. Compensation and decompensation are general medical concepts that can be applied and quantified for many, if not all, biomechanical and physiological regulatory mechanisms of the human body. This may allow for a new research strategy to quantify both aging and frailty in a systemic and dynamic way.

Cadence-based classification of moderate-intensity overground walking in 41- to 85-year-old adults

BACKGROUND

Walking cadence (steps/min) has emerged as a valid proxy of physical activity intensity, with consensus across numerous laboratory-based treadmill studies that ≥100 steps/min approximates absolutely defined moderate intensity (≥3 metabolic equivalents; METs). We recently reported that this cadence threshold had a classification accuracy of 73.3% for identifying moderate intensity during preferred pace overground walking in young adults. The purpose of this study was to evaluate and compare the performance of a cadence threshold of ≥100 steps/min for correctly classifying moderate intensity during overground walking in middle- and older-aged adults.

METHODS

Participants (N = 174, 48.3% female, 41-85 years of age) completed laboratory-based cross-sectional study involving an indoor 5-min overground walking trial at their preferred pace. Steps were manually counted and converted to cadence (total steps/5 min). Intensity was measured using indirect calorimetry and expressed as METs. Classification accuracy (sensitivity, specificity, accuracy) of a cadence threshold of ≥100 steps/min to identify individuals walking at ≥3 METs was calculated.

RESULTS

The ≥100 steps/min threshold demonstrated accuracy of 74.7% for classifying moderate intensity. When comparing middle- vs. older-aged adults, similar accuracy (73.4% vs. 75.8%, respectively) and specificity (33.3% vs. 34.5%) were observed. Sensitivity was high, but was lower for middle- vs. older-aged adults (85.2% vs. 93.9%, respectively).

CONCLUSION

A cadence threshold of ≥100 steps/min accurately identified moderate-intensity overground walking. Furthermore, accuracy was similar when comparing middle- and older-aged adults. These findings extend our previous analysis in younger adults and confirm the appropriateness of applying this cadence threshold across the adult lifespan.

Moderate-intensity stepping in older adults: insights from treadmill walking and daily living

BACKGROUND

A step cadence of 100 steps/minute is widely used to define moderate-intensity walking. However, the generalizability of this threshold to different populations needs further research. We investigate moderate-intensity step cadence values during treadmill walking and daily living in older adults.

METHODS

Older adults (≥ 60 years) were recruited from urban community venues. Data collection included 7 days of physical activity measured by an activPAL3™ thigh worn device, followed by a laboratory visit involving a 60-min assessment of resting metabolic rate, then a treadmill assessment with expired gas measured using a breath-by-breath analyser and steps measured by an activPAL3™. Treadmill stages were undertaken in a random order and lasted 5 min each at speeds of 1, 2, 3, 4 and 5 km/h. Metabolic equivalent values were determined for each stage as standardised values (METS_standard) and as multiples of resting metabolic rate (METS_relative). A value of 3 METS_standard defined moderate-intensity stepping. Segmented generalised estimating equations modelled the association between step cadence and MET values.

RESULTS

The study included 53 participants (median age = 75, years, BMI = 28.0 kg/m², 45.3% women). At 2 km/h, the median METS_standard and METS_relative values were above 3 with a median cadence of 81.00 (IQR 72.00, 88.67) steps/minute. The predicted cadence at 3 METS_standard was 70.3 (95% CI 61.4, 75.8) steps/minute. During free-living, participants undertook median (IQR) of 6988 (5933, 9211) steps/day, of which 2554 (1297, 4456) steps/day were undertaken in continuous stepping bouts lasting ≥ 1 min. For bouted daily steps, 96.4% (90.7%, 98.9%) were undertaken at ≥ 70 steps/minute.

CONCLUSION

A threshold as low as 70 steps/minute may be reflective of moderate-intensity stepping in older adults, with the vast majority of all bouted free-living stepping occurring above this threshold.

Exploring the associations of daily movement behaviours and mid-life cognition: a compositional analysis of the 1970 British Cohort Study

BACKGROUND

Movement behaviours (eg, sedentary behaviour (SB), moderate and vigorous physical activity (MVPA), light intensity physical activity (LIPA) and sleep) are linked to cognition, yet the relative importance of each component is unclear, and not yet explored with compositional methodologies.

OBJECTIVE

To (i) assess the associations of different components of daily movement and participant's overall cognition, memory and executive function, and (ii) understand the relative importance of each individual component for cognition.

METHODS

The 1970 British Cohort Study (BCS70) is a prospective birth cohort study of UK-born adults. At age 46, participants consented to wear an accelerometer device and complete tests of verbal memory and executive function. Compositional linear regression was used to examine cross-sectional associations between 24-hour movement behaviours and standardised cognition scores. Isotemporal substitution was performed to model the effect of reallocating time between components of daily movement on cognition.

RESULTS

The sample comprised 4481 participants (52% female). Time in MVPA relative to SB, LIPA and sleep was positively associated with cognition after adjustments for education and occupational physical activity, but additional adjustment for health status attenuated associations. SB relative to all other movements was robustly positively associated with cognition. Modelling time reallocation between components revealed an increase in cognition centile after MVPA theoretically replaced 9 min of SB (OR=1.31; 95% CI 0.09 to 2.50), 7 min of LIPA (1.27; 0.07 to 2.46) or 7 min of sleep (1.20; 0.01 to 2.39).

CONCLUSIONS

Relative to time spent in other behaviours, greater MVPA and SB was associated with higher cognitive scores. Loss of MVPA time, given its smaller relative amount, appears most deleterious. Efforts should be made to preserve MVPA time, or reinforce it in place of other behaviours.

How many days are needed? Measurement reliability of wearable device data to assess physical activity

INTRODUCTION/PURPOSE

Physical activity studies often utilize wearable devices to measure participants' habitual activity levels by averaging values across several valid observation days. These studies face competing demands-available resources and the burden to study participants must be balanced with the goal to obtain reliable measurements of a person's longer-term average. Information about the number of valid observation days required to reliably measure targeted metrics of habitual activity is required to inform study design.

METHODS

To date, the number of days required to achieve a desired level of aggregate long-term reliability (typically 0.80) has often been estimated by applying the Spearman-Brown Prophecy formula to short-term test-retest reliability data from studies with single, relatively brief observation windows. Our work, in contrast, utilizes a resampling-based approach to quantify the long-term test-retest reliability of aggregate measures of activity in a cohort of 79 participants who were asked to wear a FitBit Flex every day for approximately one year.

RESULTS

The conventional approach can produce reliability estimates that substantially overestimate the actual test-retest reliability. Six or more valid days of observation for each participant appear necessary to obtain 0.80 reliability for the average amount of time spent in light physical activity; 8 and 10 valid days are needed for sedentary time and moderate/vigorous activity respectively.

CONCLUSION

Protocols that result in 7-10 valid observation days for each participant may be needed to obtain reliable measurements of key physical activity metrics.

Validity and Accuracy of Step Count as an Indicator of a Sedentary Lifestyle in People With Chronic Obstructive Pulmonary Disease

OBJECTIVE

To determine the validity and accuracy of <5000 steps/day as a sedentary lifestyle indicator, and the optimal step count cut point value for indicating a sedentary lifestyle in people with chronic obstructive pulmonary disease (COPD).

DESIGN

Analysis of baseline data from a randomized clinical trial.

SETTING

Sydney, Australia.

PARTICIPANTS

Stable COPD on the waitlist for pulmonary rehabilitation.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Step count and time in sedentary behavior (SB) were assessed using thigh-worn accelerometry. A sedentary lifestyle was defined as <5000 steps/day. Pearson correlation coefficients were analyzed between step count and time spent in SB. Sensitivity, specificity, and accuracy were calculated for the <5000 steps/day threshold. Receiver operating characteristic curves with the area under the curve were computed for step count in identifying a sedentary lifestyle.

RESULTS

69 people with COPD (mean age=74 years, SD=9; forced expiratory volume in 1 second, mean=55%, SD=19 predicted) had sufficient wear data for analysis. There was a moderate inverse correlation between step count and time spent in SB (r=-0.58, P<.001). Step count had a fair discriminative ability for identifying a sedentary lifestyle (area under the curve=0.80, 95% confidence interval [CI], 0.68-0.91). The <5000 steps/day threshold had a sensitivity, specificity, and accuracy of 82% (95% CI, 70-94), 70% (95% CI, 54-86), and 78%, respectively. A lower threshold of <4300 steps/day was more accurate for ruling in a sedentary lifestyle.

CONCLUSIONS

Compared with thigh-worn accelerometry, <5000 steps/day is a valid and reasonably accurate indicator of a sedentary lifestyle in this population.

The challenges of measuring physical activity and sedentary behaviour in people with rheumatoid arthritis

The importance of sufficient moderate-to-vigorous physical activity as a key component of a healthy lifestyle is well established, as are the health risks associated with high levels of sedentary behaviour. However, many people with RA do not undertake sufficient physical activity and are highly sedentary. To start addressing this, it is important to be able to carry out an adequate assessment of the physical activity levels of individual people in order that adequate steps can be taken to promote and improve healthy lifestyles. Different methods are available to measure different aspects of physical activity in different settings. In controlled laboratory environments, respiratory gas analysis can measure the energy expenditure of different activities accurately. In free-living environments, the doubly labelled water method is the gold standard for identifying total energy expenditure over a prolonged period of time (>10 days). To assess patterns of physical activity and sedentary behaviour in daily life, objective methods with body-worn activity monitors using accelerometry are superior to self-reported questionnaire- or diary-based methods.

Walking Attenuates Postprandial Glycemic Response: What Else Can We Do without Leaving Home or the Office?

We evaluated the effects of different exercise types suitable for a home/work setting on the postprandial glucose response. Twenty-three healthy, active, young individuals performed one of two studies (12 in Study 1 and 11 in Study 2), with four randomized protocols each. After a meal high in carbohydrate content (1 g of carbohydrate per kg of body weight), in Study 1, participants performed 30 min of either walking (WALK), bench stepping exercise (STEP) or isometric wall squat (SQUAT); in Study 2, participants performed 30 min of either walking (WALK), neuromuscular electrical stimulation alone (P_NMES) or superimposed on voluntary muscle contraction (VC_NMES). In both studies, participants performed a prolonged sitting condition (CON) that was compared to the exercise sessions. In Study 1, WALK and STEP significantly reduced the glucose peak compared to CON (p < 0.011). In Study 2, the peak was significantly reduced in WALK compared to CON, P_NMES and VC_NMES (p < 0.011) and in VC_NMES compared to CON and P_NMES (p < 0.011). A significant reduction of 3 h glucose iAUC was found for WALK and VC_NMES compared to CON and P_NMES (p < 0.033). In conclusion, WALK is the most effective strategy for improving the postprandial glycemic response. However, STEP and VC_NMES can also be used for reducing postprandial glycemia.

Evaluation of physical health status beyond daily step count using a wearable activity sensor

Physical health status defines an individual's ability to perform normal activities of daily living and is usually assessed in clinical settings by questionnaires and/or by validated tests, e.g. timed walk tests. These measurements have relatively low information content and are usually limited in frequency. Wearable sensors, such as activity monitors, enable remote measurement of parameters associated with physical activity but have not been widely explored beyond measurement of daily step count. Here we report on results from a cohort of 22 individuals with Pulmonary Arterial Hypertension (PAH) who were provided with a Fitbit activity monitor (Fitbit Charge HR^®) between two clinic visits (18.4 ± 12.2 weeks). At each clinical visit, a maximum of 26 measurements were recorded (19 categorical and 7 continuous). From analysis of the minute-to-minute step rate and heart rate we derive several metrics associated with physical activity and cardiovascular function. These metrics are used to identify subgroups within the cohort and to compare to clinical parameters. Several Fitbit metrics are strongly correlated to continuous clinical parameters. Using a thresholding approach, we show that many Fitbit metrics result in statistically significant differences in clinical parameters between subgroups, including those associated with physical status, cardiovascular function, pulmonary function, as well as biomarkers from blood tests. These results highlight the fact that daily step count is only one of many metrics that can be derived from activity monitors.

Agreement and relationship between measures of absolute and relative intensity during walking: A systematic review with meta-regression

INTRODUCTION

A metabolic equivalent (MET) is one of the most common methods used to objectively quantify physical activity intensity. Although the MET provides an 'objective' measure, it does not account for inter-individual differences in cardiorespiratory fitness. In contrast, 'relative' measures of physical activity intensity, such as heart rate reserve (HRR), do account for cardiorespiratory fitness. The purpose of this systematic review with meta-regression was to compare measures of absolute and relative physical activity intensity collected during walking.

METHODS

A systematic search of four databases (SPORTDiscus, Medline, Academic Search Premier and CINAHL) was completed. Keyword searches were: (i) step* OR walk* OR strid* OR "physical activity"; (ii) absolute OR "absolute intensity" OR mets OR metabolic equivalent OR actigraph* OR acceleromet*; (iii) relative OR "relative intensity" OR "heart rate" OR "heart rate reserve" OR "VO2 reserve" OR VO2* OR "VO2 uptake" OR HRmax* OR metmax. Categories (i) to (iii) were combined using 'AND;' with studies related to running excluded. A Bayesian regression was conducted to quantify the relationship between METs and %HRR, with Bayesian logistic regression conducted to examine the classification agreement between methods. A modified Downs and Black scale incorporating 13 questions relative to cross-sectional study design was used to assess quality and risk of bias in all included studies.

RESULTS

A total of 15 papers were included in the systematic review. A comparison of means between absolute (METs) and relative (%HRR, %HRmax, %VO2R, %VO2max, HRindex) values in 8 studies identified agreement in how intensity was classified (light, moderate or vigorous) in 60% of the trials. We received raw data from three authors, incorporating 3 studies and 290 participants. A Bayesian random intercept logistic regression was conducted to examine the agreement between relative and absolute intensity, showing agreement in 43% of all trials. Two studies had identical relative variables (%HRR) totalling 240 participants included in the Bayesian random intercept regression. The best performing model was a log-log regression, which showed that for every 1% increase in METs, %HRR increased by 1.12% (95% CI: 1.10-1.14). Specifically, the model predicts at the lower bound of absolute moderate intensity (3 METs), %HRR was estimated to be 33% (95%CI: 18-57) and at vigorous intensity (6 METs) %HRR was estimated to be 71% (38-100).

CONCLUSION

This study highlights the discrepancies between absolute and relative measures of physical activity intensity during walking with large disagreement observed between methods and large variation in %HRR at a given MET. Consequently, health professionals should be aware of this lack of agreement between absolute and relative measures. Moreover, if we are to move towards a more individualised approach to exercise prescription and monitoring as advocated, relative intensity could be more highly prioritised.

Perspectives on exercise intensity, volume, step characteristics and health outcomes in walking for transport

Background

Quantification of movement intensity and energy utilization, together with frequency of trips, duration, distance, step counts and cadence, is essential for interpreting the character of habitual walking for transport, and its potential support of health. The purpose of the study is to illuminate this with valid methods and novel perspectives, and to thereby provide a new basis for characterizing and interpreting walking in relation to health outcomes.

Methods

Habitual middle-aged commuting pedestrians (males = 10, females = 10) were investigated in the laboratory at rest and with maximal treadmill and cycle ergometer tests. Thereafter, levels of oxygen uptake, energy expenditure, ventilation, heart rate, blood lactate, rated perceived exertion, cadence, number of steps, duration, distance, and speed were recorded during the normal walking commute of each participant in Greater Stockholm, Sweden. The number of commutes per week over the year was self-reported.

Results

Walking in the field demanded about 30% more energy per km compared to level treadmill walking. For both sexes, the walking intensity in field was about 46% of maximal oxygen uptake, and energy expenditure amounted to 0.96 kcal · kg^{- 1} · km^{- 1}. The MET values (males: 6.2; females: 6.5) mirrored similar levels of walking speed (males: 5.7; females: 5.9 km · h^{- 1}) and levels of oxygen uptake (males: 18.6; females: 19.5 mL · kg^{- 1} · min^{- 1}). The average number of MET-hours per week in a typical month was 22 for males and 20 for females. This resulted in a total weekly energy expenditure of ~1,570 and 1,040 kcal for males and females, respectively. Over the year, the number of walking commutes and their accumulated distance was ~385 trips and 800 km for both sexes.

Conclusion

Walking in naturalistic field settings demands its own studies. When males and females walk to work, their relative aerobic intensities and absolute energy demands for a given distance are similar. It is equivalent to the lower part of the moderate relative intensity domain. The combination of oxygen uptake, trip duration and frequency leads to high and sustained levels of MET-hours as well as energy expenditure per week over the year, with a clear health enhancing potential. Based on this study we recommend 6000 transport steps per day, or equivalent, during five weekdays, over the year, in order to reach optimal health gains.

Detecting Parkinson's Disease through Gait Measures Using Machine Learning

Parkinson’s disease (PD) is one of the most common long-term degenerative movement disorders that affects the motor system. This progressive nervous system disorder affects nearly one million Americans, and more than 20,000 new cases are diagnosed each year. PD is a chronic and progressive painful neurological disorder and usually people with PD live 10 to 20 years after being diagnosed. PD is diagnosed based on the identification of motor signs of bradykinesia, rigidity, tremor, and postural instability. Though several attempts have been made to develop explicit diagnostic criteria, this is still largely unrevealed. In this manuscript, we aim to build a classifier with gait data from Parkinson patients and healthy controls using machine learning methods. The classifier could help facilitate a more accurate and cost-effective diagnostic method. The input to our algorithm is the Gait in Parkinson’s Disease dataset published on PhysioNet containing force sensor data as the measurement of gait from 92 healthy subjects and 214 patients with idiopathic Parkinson’s Disease. Different machine learning methods, including logistic regression, SVM, decision tree, KNN were tested to output a predicted classification of Parkinson patients and healthy controls. Baseline models including frequency domain method can reach similar performance and may be another good approach for the PD diagnostics.

Team IHMC at the 2020 Cybathlon: a user-centered approach towards personal mobility exoskeletons

Background

The past few decades have seen rapid advancements in exoskeleton technology, with a considerable shift towards applications involving users with gait pathologies. Commercial devices from ReWalk, Ekso Bionics, and Indego, mainly designed for rehabilitation purposes, have inspired the development of many research platforms aimed at extending capabilities for use as safe and effective personal mobility devices. The 2016 Cybathlon featured an impressive demonstration of exoskeletons designed to enable mobility for individuals with spinal cord injury, however, not a single team completed every task and only two completed the stairs. Major improvements were showcased at the 2020 Cybathlon, with seven of the nine teams completing a similar set of tasks. Team IHMC built upon its silver-medal success from 2016 with an upgraded device, Quix.

Methods

Quix features several notable improvements including an additional powered degree of freedom for hip ab/adduction to laterally shift the device and reduce user effort while walking, custom-tailored cuffs and soft goods based on 3D body scans to optimize user comfort, and a streamlined testing pipeline for online tuning of gait parameters.

Results

Team IHMC finished in fourth place behind the teams from EPFL and Angel Robotics. Although we suffered from a considerably slower flat-ground walking speed, our pilot reported marked improvements in overall effort, comfort, and ease-of-use compared to our previous device.

Conclusions

Clear progress in exoskeleton development has been exhibited since the inaugural Cybathlon, with tasks involving rough terrain, stairs, and ramps now posing little threat to most of the competitors. As a result, the layout of the powered exoskeleton course will likely undergo significant modifications to further push the devices towards suitability for personal everyday use. The current tasks do not address the issue of donning and doffing, nor do they simulate a scenario similar to maneuvering a kitchen to prepare a meal, for example. An additional limitation that may be more difficult to test in a competition setting is the required upper-body effort to manipulate the device in an effective manner.

Prenatal and postnatal correlates of moderate-to-vigorous physical activity in midlife: evidence from the 1970 British Cohort Study

Background

It is hypothesised that lifelong physical activity behaviours are established in early life, however there is minimal, and contradictory, evidence examining prenatal and postnatal factors in relation to adulthood physical activity. We investigated associations between prospectively ascertained prenatal/postnatal factors and device-measured moderate-to-vigorous physical activity (MVPA) in midlife.

Methods

Analyses included 5011 participants from the 1970 British Cohort Study, a birth cohort study of individuals born within the same week. At birth, the following factors were ascertained: socioeconomic position (SEP), maternal age, number of previous pregnancies, maternal smoking, maternal diabetes, gestational age, birth weight, breastfeeding status and infant health concerns. MVPA was captured at age 46 with a thigh-worn accelerometer device following a 24-hour protocol over 7 days.

Results

In sex-adjusted models, lower SEP (−6.7 min/day (95% CI: −9.0 to –4.4) in those with a partly or unskilled paternal occupation), younger maternal age (0.4 min/day (0.2 to 0.5) per additional year of maternal age), maternal smoking during pregnancy (−2.5 min/day (−4.0 to –1.0)) and post-term gestational age (−7.4 min/day (−11.5 to –3.4); boys only) were associated with lower MVPA at age 46. In the mutually adjusted model, associations did not change but there was some evidence that birth weight may also be associated with MVPA levels.

Conclusions

SEP, maternal age, maternal smoking, post-term birth in boys and birth weight were associated with MVPA in midlife, indicating that midlife physical activity behaviours may be partially established at birth. Early interventions in disadvantaged environments may have a positive impact on physical activity throughout the life course.

A catalog of validity indices for step counting wearable technologies during treadmill walking: the CADENCE-adults study

BACKGROUND

Standardized validation indices (i.e., accuracy, bias, and precision) provide a comprehensive comparison of step counting wearable technologies.

PURPOSE

To expand a previously published child/youth catalog of validity indices to include adults (21-40, 41-60 and 61-85 years of age) assessed across a range of treadmill speeds (slow [0.8-3.2 km/h], normal [4.0-6.4 km/h], fast [7.2-8.0 km/h]) and device wear locations (ankle, thigh, waist, and wrist).

METHODS

Two hundred fifty-eight adults (52.5 ± 18.7 years, 49.6% female) participated in this laboratory-based study and performed a series of 5-min treadmill bouts while wearing multiple devices; 21 devices in total were evaluated over the course of this multi-year cross-sectional study (2015-2019). The criterion measure was directly observed steps. Computed validity indices included accuracy (mean absolute percentage error, MAPE), bias (mean percentage error, MPE), and precision (correlation coefficient, r; standard deviation, SD; coefficient of variation, CoV).

RESULTS

Over the range of normal speeds, 15 devices (Actical, waist-worn ActiGraph GT9X, activPAL, Apple Watch Series 1, Fitbit Ionic, Fitbit One, Fitbit Zip, Garmin vivoactive 3, Garmin vivofit 3, waist-worn GENEActiv, NL-1000, PiezoRx, Samsung Gear Fit2, Samsung Gear Fit2 Pro, and StepWatch) performed at < 5% MAPE. The wrist-worn ActiGraph GT9X displayed the worst accuracy across normal speeds (MAPE = 52%). On average, accuracy was compromised across slow walking speeds for all wearable technologies (MAPE = 40%) while all performed best across normal speeds (MAPE = 7%). When analyzing the data by wear locations, the ankle and thigh demonstrated the best accuracy (both MAPE = 1%), followed by the waist (3%) and the wrist (15%) across normal speeds. There were significant effects of speed, wear location, and age group on accuracy and bias (both p < 0.001) and precision (p ≤ 0.045).

CONCLUSIONS

Standardized validation indices cataloged by speed, wear location, and age group across the adult lifespan facilitate selecting, evaluating, or comparing performance of step counting wearable technologies. Speed, wear location, and age displayed a significant effect on accuracy, bias, and precision. Overall, reduced performance was associated with very slow walking speeds (0.8 to 3.2 km/h). Ankle- and thigh-located devices logged the highest accuracy, while those located at the wrist reported the worst accuracy.

TRIAL REGISTRATION

Clinicaltrials.gov NCT02650258. Registered 24 December 2015.

Microplastic: A particulate matter(PM) generated by deterioration of building materials

Particulate matter (PM), an inhalable material, is generated from various sources, including building materials. To maintain indoor air quality, it is necessary to analyze harmful substances and establish a method for their remediation. The purpose of this study is to identify the particles generated during the deterioration of building materials and analyze the composition of fine dust particles with respect to the degree of deterioration. The concentration of particles generated was analyzed using an SPS30 PM sensor in the built chamber. PM10 and PM2.5 levels of the maximum of 41.95 mg/m³ and 20.63 mg/m³, respectively, were generated from the tested building materials. The components of the collected PM were carbon, hydrogen, and silicon, among others, which are high-molecular-weight compounds. Particles of size 2.5 µm or less were detected, and the possibility of generating nanoplastics was investigated.

Classification of moderate-intensity overground walking speed in 21- to 85-year-old adults

The Compendium of Physical Activities reports that walking at 2.5 mph associates with absolutely-defined moderate intensity (i.e., ≥3 metabolic equivalents [METs]). However, it is unclear whether this speed threshold is accurate during overground walking and/or across the adult age-span. This study aimed to identify optimal and heuristic speed thresholds associated with 3 METs during overground walking across age groups. Healthy adults (n = 248, 21-85 years old, 49% women) performed a 5-minute self-paced overground walking trial. Speed was measured using an electronic gait mat, and oxygen uptake was measured using indirect calorimetry and converted to METs. Optimal and heuristic thresholds and classification accuracy metrics were determined and compared using ROC curve analyses. Speed thresholds (95% CIs) associated with 3 METs for the whole sample, young (21-40 years), middle-aged (41-60 years) and older-aged (61-85 years) groups were 1.29 (1.25, 1.33), 1.30 (1,26, 1,35), and 1.25 (1.21, 1.29) m/s, respectively. Overall, 3 mph and 5 km/h performed better than 2.5 mph and 4.5 km/h in balancing both sensitivity and specificity (higher Youden's Indices). Overground walking speeds associated with 3 METs were similar across age groups. A heuristic threshold of 3 mph or 5 km/h may better identify absolutely-defined moderate intensity overground walking.

Effects of different exercise intensities on prefrontal activity during a dual task

The effects of physical exercise on cognitive tasks have been investigated. However, it is unclear how different exercise intensities affect the neural activity. In this study, we investigated the neural activity in the prefrontal cortex (PFC) by varying the exercise intensity while participants performed a dual task (DT). Twenty healthy young adults performed serial subtraction while driving a cycle ergometer. Exercise intensity was set to one of three levels: low, moderate, or high intensity. We did not find any significant change in PFC activity during DT under either the control (no exercise) or low-intensity conditions. In contrast, we observed a significant increase in PFC activity during DT under moderate- and high-intensity conditions. In addition, we observed complex hemodynamics after DT. PFC activity decreased from baseline after DT under the control condition, while it increased under the low-intensity condition. PFC activity remained higher than the baseline level after DT under the moderate-intensity condition but returned to baseline under the high-intensity condition. The results suggest that moderate-intensity exercise with a cognitive load effectively increases PFC activity, and low-intensity exercise may increase PFC activity when combined with a cognitive load.

Dose-response association between step count and cardiovascular disease risk markers in middle-aged adults

Several step-based daily targets have been widely circulated, but there is a lack of empirical population-based evidence to support such guidance. We examined dose-response associations between step count and classical CVD risk markers (glycated hemoglobin, high density lipoprotein cholesterol, triglycerides, and C-reactive protein) in 4665 adults (aged 46 years; 51.4% female) in a cross-sectional study. Step counts were measured from a thigh mounted accelerometer (activPAL) worn over 7 days. The shape of the dose-response curve for most risk markers was "L-shaped," with linear risk reduction up to around 10 000 steps a day. Controlling for stepping intensity did not materially alter our results.

Objectively-measured step cadence and walking patterns in a rural African setting: a cross-sectional analysis

Objectives

To investigate free-living, accelerometry-derived step cadence and walking strategy parameters in 263 adult women (19–56 years) within a rural African setting. Participants were categorised into weight groups: Under-to-Normal Weight (UW/NW: < 25 kg/m²), Overweight-to-Obese (OW/OB: ≥ 25 kg/m²). From the minute-by-minute uni-axial accelerometry data, outcomes describing physical activity intensity, step volume, step cadence and step bouts were extracted. In addition, walking pattern parameters for step bout length and step cadence were determined.

Results

Average step volume was 13,568 steps/day, and > 85% of participants were classified as active-to-highly-active. Overall, ≈ 45% of daily steps was accumulated in the low-to-moderate intensity range. Peak cadence indices were higher in the UW/NW group (p ≤ 0.0112). For both groups, 75% of steps were accumulated in bouts > 15 min, and 95% of bouts were accumulated at 1–39 steps/min. The UW/NW group employed a more varied step cadence, and higher cadences contributed more to step accumulation than the OW/OB group (p ≤ 0.05). There were no significant group differences in bout length strategy parameters (p ≥ 0.0861). Despite no difference between the weight groups in step volume, there were differences in some step cadence indices which reflect higher step intensities, and in cadence strategies chosen to accumulate steps.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-022-06045-9.

Sedentary behaviour and physical activity are associated with biomarkers of endothelial dysfunction and low-grade inflammation-relevance for (pre)diabetes: The Maastricht Study

AIMS/HYPOTHESIS

Biomarkers of endothelial dysfunction and low-grade inflammation are important in the pathogenesis of CVD and can potentially be modified by physical activity and sedentary behaviour. Effects of physical activity on biomarkers of endothelial dysfunction may be especially prominent in type 2 diabetes.

METHODS

In the population-based Maastricht Study (n = 2363, 51.5% male, 28.3% type 2 diabetes, 15.1% prediabetes [defined as impaired glucose tolerance and impaired fasting glucose]), we determined biomarkers of endothelial dysfunction and low-grade inflammation, and combined z scores were calculated. Physical activity and sedentary behaviour were measured by activPAL. Linear regression analyses were used with adjustment for demographic, lifestyle and cardiovascular risk factors.

RESULTS

The association between total, light, moderate-to-vigorous and vigorous intensity physical activity and sedentary time on the one hand and biomarkers of endothelial dysfunction on the other were generally significant and were consistently stronger in prediabetes and type 2 diabetes as compared with normal glucose metabolism status (p for interaction <0.05). Associations between physical activity and sedentary behaviour on the one hand and low-grade inflammation on the other were also significant and were similar in individuals with and without (pre)diabetes (p for interaction >0.05).

CONCLUSIONS/INTERPRETATION

Physical activity and sedentary behaviour are associated with biomarkers of endothelial dysfunction and low-grade inflammation. For biomarkers of endothelial dysfunction, associations between physical activity and sedentary behaviour were consistently stronger in (pre)diabetes than in normal glucose metabolism. Whether increasing physical activity or decreasing sedentary time can positively influence biomarkers of endothelial dysfunction in individuals with prediabetes and type 2 diabetes requires further study.

A Wearable Soft Robotic Exoskeleton for Hip Flexion Rehabilitation

Leg motion is essential to everyday tasks, yet many face a daily struggle due to leg motion impairment. Traditional robotic solutions for lower limb rehabilitation have arisen, but they may bare some limitations due to their cost. Soft robotics utilizes soft, pliable materials which may afford a less costly robotic solution. This work presents a soft-pneumatic-actuator-driven exoskeleton for hip flexion rehabilitation. An array of soft pneumatic rotary actuators is used for torque generation. An analytical model of the actuators is validated and used to determine actuator parameters for the target application of hip flexion. The performance of the assembly is assessed, and it is found capable of the target torque for hip flexion, 19.8 Nm at 30°, requiring 86 kPa to reach that torque output. The assembly exhibits a maximum torque of 31 Nm under the conditions tested. The full exoskeleton assembly is then assessed with healthy human subjects as they perform a set of lower limb motions. For one motion, the Leg Raise, a muscle signal reduction of 43.5% is observed during device assistance, as compared to not wearing the device. This reduction in muscle effort indicates that the device is effective in providing hip flexion assistance and suggests that pneumatic-rotary-actuator-driven exoskeletons are a viable solution to realize more accessible options for those who suffer from lower limb immobility.

Fusion of Human Gaze and Machine Vision for Predicting Intended Locomotion Mode

Predicting the user's intended locomotion mode is critical for wearable robot control to assist the user's seamless transitions when walking on changing terrains. Although machine vision has recently proven to be a promising tool in identifying upcoming terrains in the travel path, existing approaches are limited to environment perception rather than human intent recognition that is essential for coordinated wearable robot operation. Hence, in this study, we aim to develop a novel system that fuses the human gaze (representing user intent) and machine vision (capturing environmental information) for accurate prediction of the user's locomotion mode. The system possesses multimodal visual information and recognizes user's locomotion intent in a complex scene, where multiple terrains are present. Additionally, based on the dynamic time warping algorithm, a fusion strategy was developed to align temporal predictions from individual modalities while producing flexible decisions on the timing of locomotion mode transition for wearable robot control. System performance was validated using experimental data collected from five participants, showing high accuracy (over 96% in average) of intent recognition and reliable decision-making on locomotion transition with adjustable lead time. The promising results demonstrate the potential of fusing human gaze and machine vision for locomotion intent recognition of lower limb wearable robots.

Technology-based contingency management for walking to prevent prolonged periods of workday sitting

Sedentary behavior is an emerging public health issue. Frequent, brief bouts of walking are recommended by experts to reduce the health risks correlated with physical inactivity and prolonged sedentary periods. The purpose of the current study was to extend the literature by evaluating a remote, technology-based contingency management (CM) intervention that reinforced frequent, brief bouts of walking to decrease prolonged periods of sitting during the workday. A packaged intervention consisting of a contingency contract, monetary incentives, goal setting, textual prompts, and performance feedback was implemented with individuals with sedentary job responsibilities working from home during the COVID-19 pandemic. The intervention increased the number of physically active intervals to mastery for 4 participants, thereby disrupting prolonged periods of sedentary time. For 2 participants, the intervention did not meaningfully increase the number of physically active intervals. Results suggest that a remote, digital CM intervention can decrease sedentary behavior in home office environments.

The Effects of Postprandial Walking on the Glucose Response after Meals with Different Characteristics

We evaluated the effect of postprandial walking on the post-meal glycemic response after meals with different characteristics. Twenty-one healthy young volunteers participated in one of two randomized repeated measures studies. Study 1 (10 participants) assessed the effects of 30 min of brisk walking after meals with different carbohydrate (CHO) content (0.75 or 1.5 g of CHO per kg/body weight). Study 2 (11 participants) evaluated the effects of 30 min of brisk walking after consuming a mixed meal or a CHO drink matched for absolute CHO content (75 g). Postprandial brisk walking substantially reduced (p < 0.009) the glucose peak in both studies, with no significant differences across conditions. When evaluating the glycemic response throughout the two hours post-meal, postprandial walking was more effective after consuming a lower CHO content (Study 1), and similarly effective after a mixed meal or a CHO drink (Study 2), although higher glucose values were observed when consuming the CHO drink. Our findings show that a 30 min postprandial brisk walking session improves the glycemic response after meals with different CHO content and macronutrient composition, with implications for postprandial exercise prescription in daily life scenarios.

Clubfoot Activity and Recurrence Exercise Study (CARES)

BACKGROUND

Approximately half of treated clubfoot patients initially corrected with the Ponseti method experience relapse that requires additional treatment. The consequences of relapse on childhood activity levels have not been well studied. Ponseti noted lower functional ratings at 18-year follow-up in clubfoot patients who had undergone tibialis anterior tendon transfer for relapse.

METHODS

Clubfoot Activity and Recurrence Exercise study (CARES) is an observational, prospective cohort study that compares physical activity in 30 clubfoot patients without and with relapse. Eligible participants were 5 to 10 years old, diagnosed with idiopathic clubfoot at birth, and had not received any clubfoot treatment for at least 6 months before study. Recruitment for this study occurred in-person and through Facebook clubfoot groups. Consented participants wore Fitbits secured to their wrists for at least 14 days, and completed a demographic survey, Child Health Questionnaire (CHQ), and the clubfoot disease-specific instrument (CDSI). Participants' daily activity was monitored through Fitabase.

RESULTS

Participants without and with clubfoot relapse had similar daily step counts, distance walked, and step intensities, except for moderately active step intensity, which was higher in the clubfoot relapse group. Total steps, total distance, distances (very active, moderately active), minutes (very active, fairly active), and lightly active intensity of steps were significantly higher for participants whose families earn more than $100,000 per year. Various physical activities and sports were reported by both groups in daily activity sheets. Neither demographics nor the CDSI or the CHQ scores significantly differed between the 2 groups. Step counts of children with clubfoot with or without relapse were similar to published levels for healthy children.

CONCLUSION

Children with clubfoot initially treated with the Ponseti method who undergo treatment for relapse have comparable physical activity to those who have not relapsed. They also have comparable step counts to that of the general pediatric population. These reassuring findings can guide conversations with parents when addressing concerns regarding their children's physical activity after treatment for relapse of clubfoot deformity.

LEVEL OF EVIDENCE

Level II-therapeutic studies-investigating the results of treatment.

Differences in Park Walking, Comparing the Physically Inactive and Active Groups: Data from mHealth Monitoring System in Seoul

Despite the overall increase in physical activities and park uses, the discrepancies between physically inactive and active people have increasing widened in recent times. This paper aims to empirically measure the differences in walking activity in urban parks between the physically inactive and active. As for the dataset, 22,744 peoples' 550,234 walking bouts were collected from the mHealth system of the Seoul government, using the smartphone healthcare app, WalkOn, from September to November 2019, in Seocho-gu district, Seoul, Korea. We classified the physically inactive and active sample groups, based on their regular walking (≥150 min of moderate-to-vigorous walking activity a week), and analyzed their park walking activities. We found that while there was no significant difference in walking measures of non-park walking between the sample groups, the difference did exist in park walking. The park walking average in the physically active group had more steps (p = 0.021), longer time (p = 0.008), and higher intensity (p < 0.001) of walking than that in the inactive group. Each park also revealed differences in its on-site park walking quantity and quality, based on which we could draw the list of 'well-walked parks', which held more bouts and more moderate-to-vigorous physical activities (MVPAs) than other parks in Seocho-gu district. This paper addresses how park walking of physically inactive and active people is associated with multiple differences in everyday urban walking.

The Dilemma of Analyzing Physical Activity and Sedentary Behavior with Wrist Accelerometer Data: Challenges and Opportunities

Physical behaviors (e.g., physical activity and sedentary behavior) have been the focus among many researchers in the biomedical and behavioral science fields. The recent shift from hip- to wrist-worn accelerometers in these fields has signaled the need to develop novel approaches to process raw acceleration data of physical activity and sedentary behavior. However, there is currently no consensus regarding the best practices for analyzing wrist-worn accelerometer data to accurately predict individuals' energy expenditure and the times spent in different intensities of free-living physical activity and sedentary behavior. To this end, accurately analyzing and interpreting wrist-worn accelerometer data has become a major challenge facing many clinicians and researchers. In response, this paper attempts to review different methodologies for analyzing wrist-worn accelerometer data and offer cutting edge, yet appropriate analysis plans for wrist-worn accelerometer data in the assessment of physical behavior. In this paper, we first discuss the fundamentals of wrist-worn accelerometer data, followed by various methods of processing these data (e.g., cut points, steps per minute, machine learning), and then we discuss the opportunities, challenges, and directions for future studies in this area of inquiry. This is the most comprehensive review paper to date regarding the analysis and interpretation of free-living physical activity data derived from wrist-worn accelerometers, aiming to help establish a blueprint for processing wrist-derived accelerometer data.

What do masks mask? A study on transdermal CO2 monitoring

Medical professionals have complained of extreme discomfort and fatigue from continuous wearing of N95 respirators (N95) overlaid with surgical masks (SM) and face shields (FS) during COVID-19 pandemic. However, there are no reports on the effect of face coverings on transdermal CO₂ (TrCO₂) levels (a measure of blood CO₂) during moderate activity. In this study, real-time monitoring of TrCO₂, heart rate and skin surface temperature was conducted for six subjects aged 20-59 years with and without wearing personal protective equipment (PPE). We initially studied the effect of wearing PPE (N95+SM+FS) at rest. Then, the effect of moderate stepping/walking activity (120 steps per minute for 60 min) while wearing PPE was evaluated. In addition, we investigated the effect of exercising intensity with different masks. We observed a significant difference (p < 0.0001) in TrCO₂ levels between without and with PPE during moderate exercise, but not while resting. TrCO₂ levels were correlated to exercise intensity independently with masking condition and breathability of masks. For the first time, we present data showing that a properly fitting N95 worn along with SM and FS consistently leads to elevated TrCO₂ under moderate exertion, which could contribute to fatigue over long-term use.

A Transparent Method for Step Detection using an Acceleration Threshold

Step-based metrics provide simple measures of ambulatory activity, yet device software either includes undisclosed proprietary step detection algorithms or simply do not compute step-based metrics. We aimed to develop and validate a simple algorithm to accurately detect steps across various ambulatory and non-ambulatory activities. Seventy-five adults (21-39 years) completed seven simulated activities of daily living (e.g., sitting, vacuuming, folding laundry) and an incremental treadmill protocol from 0.22-2.2ms^-1. Directly observed steps were hand-tallied. Participants wore GENEActiv and ActiGraph accelerometers, one of each on their waist and on their non-dominant wrist. Raw acceleration (g) signals from the anterior-posterior, medial-lateral, vertical, and vector magnitude (VM) directions were assessed separately for each device. Signals were demeaned across all activities and bandpass filtered [0.25, 2.5Hz]. Steps were detected via peak picking, with optimal thresholds (i.e., minimized absolute error from accumulated hand counted) determined by iterating minimum acceleration values to detect steps. Step counts were converted into cadence (steps/minute), and k-fold cross-validation quantified error (root mean squared error [RMSE]). We report optimal thresholds for use of either device on the waist (threshold=0.0267g) and wrist (threshold=0.0359g) using the VM signal. These thresholds yielded low error for the waist (RMSE<173 steps, ≤2.28 steps/minute) and wrist (RMSE<481 steps, ≤6.47 steps/minute) across all activities, and outperformed ActiLife's proprietary algorithm (RMSE=1312 and 2913 steps, 17.29 and 38.06 steps/minute for the waist and wrist, respectively). The thresholds reported herein provide a simple, transparent framework for step detection using accelerometers during treadmill ambulation and activities of daily living for waist- and wrist-worn locations.