Walking cadence (steps/min) and intensity in 61-85-year-old adults: the CADENCE-Adults study

Gait differences between COPD and healthy controls: systematic review and meta-analysis

BACKGROUND

Despite the importance of gait as a determinant of falls, disability and mortality in older people, understanding of gait impairment in COPD is limited. This study aimed to identify differences in gait characteristics during supervised walking tests between people with COPD and healthy controls.

METHODS

We searched 11 electronic databases, supplemented by Google Scholar searches and manual collation of references, in November 2019 and updated the search in July 2021. Record screening and information extraction were performed independently by one reviewer and checked for accuracy by a second. Meta-analyses were performed in studies not considered at a high risk of bias.

RESULTS

Searches yielded 21 085 unique records, of which 25 were included in the systematic review (including 1015 people with COPD and 2229 healthy controls). Gait speed was assessed in 17 studies (usual speed: 12; fast speed: three; both speeds: two), step length in nine, step duration in seven, cadence in six, and step width in five. Five studies were considered at a high risk of bias. Low-quality evidence indicated that people with COPD walk more slowly than healthy controls at their usual speed (mean difference (MD) -19 cm·s-1, 95% CI -28 to -11 cm·s-1) and at a fast speed (MD -30 cm·s-1, 95% CI -47 to -13 cm·s-1). Alterations in other gait characteristics were not statistically significant.

CONCLUSION

Low-quality evidence shows that people with COPD walk more slowly than healthy controls, which could contribute to an increased falls risk. The evidence for alterations in spatial and temporal components of gait was inconclusive. Gait impairment appears to be an important but understudied area in COPD.

Physical Activity Levels and Sedentary Behavior of People Living With Mild Cognitive Impairment: A Cross-Sectional Study Using Thigh-Worn Accelerometers

Community-dwelling people with Mild Cognitive Impairment self-reporting not to be meeting recommended physical activity levels participated in this study to (a) determine compliance of wearing (thigh-worn) accelerometers, (b) describe physical activity levels and sedentary behavior, and (c) determine the validity of the Physical Activity Scale for the Elderly (PASE) compared with activPAL accelerometers. A total of 79 people had valid accelerometer data (median [interquartile range]: age, 71 [54-75] years). Compliance was 86.81%. Participants were sedentary for 10.6 hr per day and engaged in a median of 9 min per day of moderate-intensity physical activity. Fair correlations were found between the PASE and total stepping time per day (r = .35, p < .01), total number of steps per day (r = .36, p < .01), and number of steps in stepping activities completed for ≤1 min (r = .42, p < .01). The PASE and Standing time (r = .04, p = .724) and PASE and Sitting time (r = .04, p = .699) had little to no relationship. The use of thigh-worn accelerometers for this population is achievable. People with Mild Cognitive Impairment have high levels of sedentary behavior and minimal engagement in moderate-intensity physical activity. The PASE has fair, positive criterion validity with activity-based outcomes measured by activPAL accelerometers but not with sedentary behavior, which is high for this population.

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.

Validation of "CENTR(AR)" walking trails: Different field criteria do not lead to different physical activity intensities in people with COPD

BACKGROUND

Validating walking trails is essential to promote physical activity (PA) safely and confidently in people with COPD.

OBJECTIVES

We aimed to validate predetermined light, moderate, and vigorous intensities of walking trails in people with COPD.

METHODS

This cross-sectional study included individuals with COPD walking in predetermined light, moderate and vigorous intensity trails. Activity intensity and volume outcomes were collected. Dyspnoea and fatigue (modified Borg scale), energy expenditure (EE, Sensewear), heart rate (HR, HR monitor), time spent in different PA intensities, and cadence (ActiGraph) were recorded and used to classify PA intensity.

RESULTS

Twenty people with COPD [71(7) years, 80 % male, FEV1%predicted 65.6(11.6)] were included. Fatigue differed significantly between light and moderate [3.0(2.0;4.0) vs 3.4(2.5;4.5), p = 0.01], but not vigorous (3.5[2.5-4.0]) tracks. Dyspnoea [2.3(1.5) vs 2.7(1.6) vs 2.6(1.4)], EE [5.1(0.8) vs 4.9(0.5) vs 4.6(0.8) METs], HR [92.5(11.1) vs 93.7(18.6) vs 95.4(15.0) beats/min] and cadence [115.1(104.0;120.3) vs 104.7(99.6;117.6) vs 111.2(99.9;118.5) steps/min] were similar across trails (p > 0.05). Time spent in light and moderate PA, EE volume, walking time, and step count increased along with the proposed intensity levels (p < 0.01). Walking trails were categorised as moderate intensity in most participants.

CONCLUSION

Walking trails were safe and valid for practising moderate-intensity PA in people with COPD. Participants adjusted their physiological responses and perceived symptoms to match a moderate intensity.

Associations between physical activity, sedentary behaviour and cognitive domain performance of people living with mild cognitive impairment in the community

INTRODUCTION

Physical activity is known to positively influence cognitive performance. For adults with mild cognitive impairment (MCI), the relationship between physical activity levels and cognitive performance is unknown. This cross-sectional study aimed to determine if cognitive performance [as measured by the Montreal Cognitive Assessment (MoCA)] of people living in the community with MCI is associated with their physical activity levels or sedentary behaviour.

METHODS

ActivPAL™ accelerometers were used to objectively measure physical activity and sedentary behaviour for seven full days. Cognitive performance was measured using the MoCA.

CONSUMER AND COMMUNITY INVOLVEMENT

No involvement other than as research participants RESULTS: Eighty-two participants from the Balance on the Brain randomised controlled trial were included. Most participants were retired (88%), with 33 (40%) reporting a fall in the last year. The median MoCA score was 24 (IQR 22-26). Participants achieved a mean of 6296 (±2420) steps per day and were sedentary for 10.6 (±2) hours per day. The only physical activity outcomes that had a fair, positive correlation were moderate- to vigorous-intensity physical activity measures of total stepping time and total number of steps (with a cadence of ≥100 steps/min) with the orientation MoCA domain score (r(82) = 0.36, p ≤ 0.001 and r(82) = 0.37, p ≤ 0.001, respectively). Higher total sedentary time had a weak, positive correlation with better visuospatial/executive performance (r(82) = 0.23, p = 0.041). The orientation outcomes remained significant when analysed in an adjusted logistic regression model.

CONCLUSION

This study found that performance in the MoCA orientation domain had a fair-positive correlation with moderate-intensity physical activity (i.e., stepping time and step count with a cadence of ≥100 steps/min) as measured by a thigh-worn accelerometer for community-dwelling older adults with MCI. When considering the relationship between cognitive domains and sedentary behaviour, consideration may be needed regarding whether cognitive enhancing activities (such as crosswords and other brain games) are being performed, which may confound this relationship. Further investigation is required to confirm these results.

Exploring the electrical robustness of conductive textile fasteners for wearable devices in different human motion conditions

Conventional snap fasteners used in clothing are often used as electrical connectors in e-textile and wearable applications for signal transmission due to their wide availability and ease of use. Nonetheless, limited research exists on the validation of these fasteners, regarding the impact of contact-induced high-amplitude artefacts, especially under motion conditions. In this work, three types of fasteners were used as electromechanical connectors, establishing the interface between a regular sock and an acquisition device. The tested fasteners have different shapes and sizes, as well as have different mechanisms of attachment between the plug and receptacle counterparts. Experimental evaluation was performed under static conditions, slow walking, and rope jumping at a high cadence. The tests were also performed with a test mass of 140 g. Magnetic fasteners presented excellent electromechanical robustness under highly dynamic human movement with and without the additional mass. On the other hand, it was demonstrated that the Spring snap buttons (with a spring-based engaging mechanism) presented a sub-optimal performance under high motion and load conditions, followed by the Prong snap fasteners (without spring), which revealed a high susceptibility to artefacts. Overall, this work provides further evidence on the importance and reliability of clothing fasteners as electrical connectors in wearable systems.

A Low or High Physical Activity Level Does Not Modulate Prostate Tumor Tissue Protein Synthesis Rates

INTRODUCTION

Physical activity level has been identified as an important factor in the development and progression of various types of cancer. In this study, we determined the impact of a low versus high physical activity level on skeletal muscle, healthy prostate, and prostate tumor protein synthesis rates in vivo in prostate cancer patients.

METHODS

Thirty prostate cancer patients (age, 66 ± 5 yr; body mass index, 27.4 ± 2.9 kg·m -2 ) were randomized to a low (<4000 steps per day, n = 15) or high (>14,000 steps per day, n = 15) physical activity level for 7 d before their scheduled radical prostatectomy. Daily deuterium oxide administration was combined with the collection of plasma, skeletal muscle, nontumorous prostate, and prostate tumor tissue during the surgical procedure to determine tissue protein synthesis rates throughout the intervention period.

RESULTS

Daily step counts averaged 3610 ± 878 and 17,589 ± 4680 steps in patients subjected to the low and high physical activity levels, respectively ( P < 0.001). No differences were observed between tissue protein synthesis rates of skeletal muscle, healthy prostate, or prostate tumor between the low (1.47% ± 0.21%, 2.74% ± 0.70%, and 4.76% ± 1.23% per day, respectively) and high (1.42% ± 0.16%, 2.64% ± 0.58%, and 4.72% ± 0.80% per day, respectively) physical activity group (all P > 0.4). Tissue protein synthesis rates were nearly twofold higher in prostate tumor compared with nontumorous prostate tissue.

CONCLUSIONS

A short-term high or low physical activity level does not modulate prostate or prostate tumor protein synthesis rates in vivo in prostate cancer patients. More studies on the impact of physical activity level on tumor protein synthesis rates and tumor progression are warranted to understand the potential impact of lifestyle interventions in the prevention and treatment of cancer.

Remotely delivered exercise to older rural cancer survivors: a randomized controlled pilot trial

PURPOSE

The study aimed to determine the feasibility of remotely delivered exercise (tele-exercise) for older, rural cancer survivors and to explore the effects of tele-exercise on physical function, physical activity, and patient-reported outcomes.

METHODS

Participants were rural cancer survivors age ≥ 60 years (79% female; mean age 70.4 ± 5.7) randomly assigned to the remotely delivered EnhanceFitness (tele-EF) exercise program, inclusive of aerobic, strength, and balance training and led by American Council on Exercise certified instructors for 1 h, 3 days/week for 16 weeks (n = 20) or to a waitlist control group (n = 19). We assessed feasibility, physical function, accelerometer-measured physical activity, and patient-reported outcomes at baseline and post intervention.

RESULTS

Among those screened as eligible, 44 (64%) consented to participate with 39 randomized after completing baseline measures. Attrition was equivalent between groups (n = 1, each) with 95% completing the study. The median class attendance rate was 86.9% (interquartile range: 79-94%). Compared to controls, tele-EF participants had statistically significant improvement in the five-time sit-to-stand test (- 3.4 vs. - 1.1 s, p = 0.03, effect size = 0.44), mean daily light physical activity (+ 38.5 vs 0.5 min, p = 0.03, effect size = 0.72) and step counts (+ 1977 vs. 33, p = 0.01, effect size = 0.96). There were no changes in self-efficacy for exercise, fatigue, or sleep disturbance between groups.

CONCLUSIONS

Findings indicate that tele-EF is feasible in older, rural cancer survivors and results in positive changes in physical function and physical activity.

IMPLICATIONS FOR CANCER SURVIVORS

Tele-EF addresses common barriers to exercise for older, rural cancer survivors, including limited accessible opportunities for professional instruction and supervision.

Real-world walking cadence in people with COPD

Introduction

The clinical validity of real-world walking cadence in people with COPD is unsettled. Our objective was to assess the levels, variability and association with clinically relevant COPD characteristics and outcomes of real-world walking cadence.

Methods

We assessed walking cadence (steps per minute during walking bouts longer than 10 s) from 7 days' accelerometer data in 593 individuals with COPD from five European countries, and clinical and functional characteristics from validated questionnaires and standardised tests. Severe exacerbations during a 12-month follow-up were recorded from patient reports and medical registries.

Results

Participants were mostly male (80%) and had mean±sd age of 68±8 years, post-bronchodilator forced expiratory volume in 1 s (FEV1) of 57±19% predicted and walked 6880±3926 steps·day-1. Mean walking cadence was 88±9 steps·min-1, followed a normal distribution and was highly stable within-person (intraclass correlation coefficient 0.92, 95% CI 0.90-0.93). After adjusting for age, sex, height and number of walking bouts in fractional polynomial or linear regressions, walking cadence was positively associated with FEV1, 6-min walk distance, physical activity (steps·day-1, time in moderate-to-vigorous physical activity, vector magnitude units, walking time, intensity during locomotion), physical activity experience and health-related quality of life and negatively associated with breathlessness and depression (all p<0.05). These associations remained after further adjustment for daily steps. In negative binomial regression adjusted for multiple confounders, walking cadence related to lower number of severe exacerbations during follow-up (incidence rate ratio 0.94 per step·min-1, 95% CI 0.91-0.99, p=0.009).

Conclusions

Higher real-world walking cadence is associated with better COPD status and lower severe exacerbations risk, which makes it attractive as a future prognostic marker and clinical outcome.

High cadence cycling not high work rate, increases gait velocity post-exercise

Gait velocity, or walking speed, has been referred to as the sixth vital sign, and research suggests that it is highly sensitive to change. Previous research has demonstrated the utility of cycling to improve gait parameters and in particular gait velocity in a variety of populations. However, it is unclear if the benefits from cycling to gait velocity stem from increased cadence, increased work rate, or the interaction between them. Therefore, the objective of the current research was to explicitly test the relationship between cycling work rate, cycling cadence, and gait velocity. 45 recreationally active young adults were randomly assigned to cycle at a normalised cadence and work rate, a higher cadence, or a higher work rate (CONTROL, FAST, HARD). All participants completed two ten-metre walk tests (10 MWT) pre- and post-cycling intervention. There was a significant interaction between group and time and post hoc comparisons showed that the FAST group walked significantly faster than the HARD group post-cycling. These results support the hypothesis that cycling at a cadence greater than the comfortable walking cadence, and not cycling at an increased work rate, increased gait velocity post-exercise for all members of our sample of healthy young adults.

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.

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.

The Impact of Nordic Pole Walk Advice Alone or in Combination With Exercise Strategies on Daily Physical Activity in Patients With Intermittent Claudication: A Randomized Clinical Trial

OBJECTIVE

The impact of exercise interventions on physical activity (PA) remains undetermined in intermittent claudication, which is why it is important to include objectively measured PA as an additional endpoint. The aim of this prespecified secondary analysis of a randomized clinical trial was to investigate the impact of unsupervised Nordic pole walk advice (WA) alone or in combination with hospital-based supervised exercise (SEP) or home-based structured exercise (HSEP) on PA in patients with intermittent claudication.

METHODS

In total, 166 patients with intermittent claudication (mean age = 72 [SD = 7.4] y; 41% women) were randomized to 3 intermittent claudication-treatment strategies: WA, WA + SEP, or WA + HSEP. All patients received Nordic poles and standardized WA (≥30 min, 3 times weekly). Patients randomized to HSEP and SEP accepted participation in an additional 6-months exercise program. PA was measured with an accelerometer-based activPAL3 monitor for 7 days at baseline and at 3, 6, and 12 months. PA outcomes were steps per day, time spent within a stepping cadence ≥100 steps per minute, time spent upright, number of body transitions from sitting to standing, and number of sitting bouts of >30 minutes and >60 minutes.

RESULTS

At 1 year, no intergroup differences were observed in any of the PA variables, whereas significant intergroup differences were observed at 3 months regarding time spent within a stepping time cadence ≥100 steps per minute. The mean change for HSEP (2.47 [SD = 10.85] min) was significantly different from the mean change for WA (-3.20 [SD = 6.24] min). At 6 months, the number of sitting bouts (>60 min) for SEP was significantly different from WA (mean change = 0.24 [SD = 0.69] vs -0.23 [SD = 0.81]).

CONCLUSION

This study indicates that the addition of 6 months of HSEP or SEP does not improve PA at 1 year, as compared to unsupervised WA alone. Factors of importance for increasing PA in patients with intermittent claudication require further investigation.

IMPACT

At the 1-year follow-up, the addition of intermittent claudication-tailored additional exercise strategies did not improve daily PA in patients with intermittent claudication compared with unsupervised Nordic pole WA alone. Future studies may explore the role of behavior change techniques to increase PA in this patient group.

Association of daily step patterns with frailty in community older Chinese women

To investigate the association between the number of days an individual takes 8,000 steps or more and frailty among older chinese women. The number of days per week taking 8,000 steps or more were measured with triaxial accelerometers. The Fried Phenotype model was used to assess frailty status. Compared to participants who walked 8,000 steps or more 0 days per week, the odds ratio of frailty was lower among those who took 8,000 steps or more 1-2 days and 3-7 days per week. Additionally, taking 3,800 steps or more in bouts of ≥10 min or taking 1,500 steps or more in ≥100 steps/min was significantly and negatively associated with frailty. These foundings indicate that, in addition to participants taking 8,000 steps or more at least one day per week, step duration and intensity may also be important factors for preventing and improving frailty in older women.

Walking more, not faster, is associated with bone health in China of community-dwelling older women:A cross-sectional study

AIMS

To examine the association between daily steps and step intensity with bone health in Chinese community-dwelling older women.

METHODS

Data from 1116 women in the Physical Activity and Health in Older Women Study in China, 2021. Three bone parameters: bone quality index (BQI), speed of sound (SOS), and broadband ultrasound attenuation (BUA) were measured in the left heel using an ultrasound bone densitometer and transformed into dichotomous variables from medians. Daily steps and step intensity (slow step time, brisk step time, peak 1-min cadence, peak 30-min cadence, and peak 60-min cadence) were measured using a triaxial accelerometer. Participants with high BQI, SOS, and BUA levels were used as references for logistic regression models to explore the association of daily steps and step intensity with bone health.

RESULTS

Daily steps were positively associated with the BQI (odds ratio [OR] = 0.94, confidence interval [CI] = 0.89,1.00), SOS (OR = 0.93, CI = 0.88,0.99), and BUA (OR = 0.93, CI = 0.88,0.99) among older women. There was no significant association between peak cadence and bone health. Slow step time was positively associated with the BQI (OR = 0.94, CI = 0.90,0.99) and SOS (OR = 0.93, CI = 0.88,0.97), while brisk step time was positively associated with the BQI (OR = 0.89, CI = 0.82,0.97), SOS (OR = 0.87, CI = 0.80,0.94), and BUA (OR = 0.89, CI = 0.82,0.97). Moreover, 10,000 steps/day or more was significantly associated with the BQI (OR = 0.52, CI = 0.33,0.81), SOS (OR = 0.55, CI = 0.35,0.86), and BUA (OR = 0.45, CI = 0.28, 0.70) compared to <6000 steps/day.

CONCLUSION

Increasing the number of daily steps or the duration of walking, whether fast or slow, may benefit the bone health of older women.

Immediate Effect of Ankle Exoskeleton on Spatiotemporal Parameters and Center of Pressure Trajectory After Stroke

Gait impairments is a common condition in post-stroke subjects. We recently presented a wearable ankle exoskeleton called G-Exos, which showed that the device assisted in the ankle's dorsiflexion and inversion/reversion movements. The aim of the current pilot study was to explore spatiotemporal gait parameters and center of pressure trajectories associated with the use of the G-Exos in stroke participants. Three post-stroke subjects (52-63 years, 2 female/1 male) walked 160-meter using the G-Exos on the affected limb, on a protocol divided into 4 blocks of 40-meters: (I) without the exoskeleton, (II) with systems hybrid system, (III) active only and (IV) passive only. The results showed that the use of the exoskeleton improved swing and stance phases on both limbs, reduced stride width on the paretic limb, increased stance COP distances, and made single support COP distances more similar between the paretic and non-paretic limb. This suggests that all G-Exos systems contributed to improving body weight bearing on the paretic limb and symmetry in the gait cycle.

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.

Associations between patterns of physical activity, pain intensity, and interference among older adults with chronic pain: a secondary analysis of two randomized controlled trials

Background: Clinical management of chronic pain often includes recommendations to engage in physical activity (PA), though there are little data on the interplay between pain symptoms and key aspects of PA participation (e.g., intensity and bout duration) among older adults. Herein we investigate the longitudinal relationships between changes in PA behavior and changes in pain intensity and interference among low-active older adults with obesity and chronic pain. Methods: Participants (N = 41) were enrolled in two randomized pilot trials wherein they were assigned to an intervention focused on participation in frequent PA across the day, or to a low-contact control. Participants completed the 3-item PROMIS pain intensity scale and 8-item PROMIS pain interference scale before and after the interventions. Participants also wore an ActivPAL accelerometer for 7 days before and during the final week of the interventions. Results: A series of linear regression analyses demonstrated that increased time spent stepping at a high-light intensity in very short bouts was associated with increased pain intensity scores. By contrast, increased time spent stepping at a high-light intensity in bouts of 5-20 min was associated with reductions in pain intensity and interference scores. Increased time spent stepping at a moderate intensity overall was associated with reduced pain intensity scores, and time spent stepping at a moderate intensity for 10-20 min associated with reduced pain interference. Conclusion: These findings suggest older adults with chronic pain may benefit by moving at high-light or moderate intensities in brief bouts of at least 5 min in duration.

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.

Walk Smarter, Not Harder: Effects of Cadence Manipulation on Gait Biomechanics in Patients with Patellofemoral Osteoarthritis

PURPOSE

This study aimed to investigate the effect of walking cadence on knee flexion angular impulse and peak external flexion moment in patients with patellofemoral osteoarthritis (OA).

METHODS

Forty-eight patients with patellofemoral OA underwent repeated quantitative gait analyses on an instrumented treadmill using a randomized crossover design. Walking trials were conducted at a fixed gait speed, under three cadence conditions: (i) preferred cadence, (ii) +10% increased cadence, and (iii) -10% decreased cadence, completed in random order. Using a linear mixed model, we tested the association of cadence conditions with surrogate measures of patellofemoral load (primary outcome measure: knee flexion angular impulse) while controlling for body mass. We then repeated the analyses while sequentially replacing the dependent variable with secondary outcome measures.

RESULTS

Walking with increased cadence decreased (adjusted mean difference [95% confidence interval]) the knee flexion angular impulse (-0.85 N·m·s -1 [-1.52 to -0.18], d = 0.20) and peak knee flexion moment (-4.11 N·m [-7.35 to -0.86], d = 0.24), whereas walking with decreased cadence increased the knee flexion angular impulse (1.83 N·m·s -1 [1.15 to 2.49], d = 0.42) and peak knee flexion moment (3.55 N·m [0.30 to 6.78], d = 0.21). Similar decreases and increases were observed for secondary outcome measures.

CONCLUSIONS

Walking with increased cadence, while maintaining a fixed gait speed, reduces knee flexion angular impulse as well as other surrogate measures of knee loading in patients with patellofemoral OA.

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.

Wrist Accelerometer Estimates of Physical Activity Intensity During Walking in Older Adults and People Living With Complex Health Conditions: Retrospective Observational Data Analysis Study

BACKGROUND

Accurate measurement of daily physical activity (PA) is important as PA is linked to health outcomes in older adults and people living with complex health conditions. Wrist-worn accelerometers are widely used to estimate PA intensity, including walking, which composes much of daily PA. However, there is concern that wrist-derived PA data in these cohorts is unreliable due to slow gait speed, mobility aid use, disease-related symptoms that impact arm movement, and transient activities of daily living. Despite the potential for error in wrist-derived PA intensity estimates, their use has become ubiquitous in research and clinical application.

OBJECTIVE

The goals of this work were to (1) determine the accuracy of wrist-based estimates of PA intensity during known walking periods in older adults and people living with cerebrovascular disease (CVD) or neurodegenerative disease (NDD) and (2) explore factors that influence wrist-derived intensity estimates.

METHODS

A total of 35 older adults (n=23 with CVD or NDD) wore an accelerometer on the dominant wrist and ankle for 7 to 10 days of continuous monitoring. Stepping was detected using the ankle accelerometer. Analyses were restricted to gait bouts ≥60 seconds long with a cadence ≥80 steps per minute (LONG walks) to identify periods of purposeful, continuous walking likely to reflect moderate-intensity activity. Wrist accelerometer data were analyzed within LONG walks using 15-second epochs, and published intensity thresholds were applied to classify epochs as sedentary, light, or moderate-to-vigorous physical activity (MVPA). Participants were stratified into quartiles based on the percent of walking epochs classified as sedentary, and the data were examined for differences in behavioral or demographic traits between the top and bottom quartiles. A case series was performed to illustrate factors and behaviors that can affect wrist-derived intensity estimates during walking.

RESULTS

Participants averaged 107.7 (SD 55.8) LONG walks with a median cadence of 107.3 (SD 10.8) steps per minute. Across participants, wrist-derived intensity classification was 22.9% (SD 15.8) sedentary, 27.7% (SD 14.6) light, and 49.3% (SD 25.5) MVPA during LONG walks. All participants measured a statistically lower proportion of wrist-derived activity during LONG walks than expected (all P<.001), and 80% (n=28) of participants had at least 20 minutes of LONG walking time misclassified as sedentary based on wrist-derived intensity estimates. Participants in the highest quartile of wrist-derived sedentary classification during LONG walks were significantly older (t₁₆=4.24, P<.001) and had more variable wrist movement (t₁₆=2.13, P=.049) compared to those in the lowest quartile.

CONCLUSIONS

The current best practice wrist accelerometer method is prone to misclassifying activity intensity during walking in older adults and people living with complex health conditions. A multidevice approach may be warranted to advance methods for accurately assessing PA in these groups.

"Can Do" vs. "Do Do" in Older Adults: A Cross-Sectional Analysis of Sensor-Derived Physical Activity Patterns

(1) Background: Identifying groups with a misaligned physical capacity (PC) and physical activity (PA) is potentially relevant for health promotion. Although an important health determinant, deeper knowledge of underlying walking behavior patterns in older adults is currently missing. We aim to identify specific PA signatures of misaligned groups and determine PA variables discriminating between groups. (2) Methods: In total, 294 community-dwelling older adults (≥70 years) were divided into four quadrants based on thresholds for PA (≥ or <5000 steps/day) and PC (≤ or >12 s, Timed Up and Go test). Kruskal-Wallis and effect sizes were calculated to compare quadrants' PA variables and to determine the discriminative power of PA parameters on walking duration, frequency, and intensity. (3) Results: We identified quadrant-specific PA signatures. Compared with "can do-do do", the "cannot do-do do" group performs shorter continuous and lower-intensity walks; the "can do-do not do" group takes fewer steps and walks with less intensity. The "cannot do-do not do" group presents lower values in all PA variables. "Walking duration greater or equal 3 METs" was the strongest discriminative PA variable. (4) Conclusion: We provide distinct PA signatures for four clinically different groups of older adults. Walking intensity is most useful to distinguish community-dwelling older adults, which is relevant for developing improved customized health promotion interventions.

The elevated metabolic cost of walking at preferred speeds of healthy elderly on treadmills compared to overground is not related to increased self-reported anxiety

PURPOSE

To investigate whether the elevation in metabolic cost of walking on treadmills compared to overground for healthy elderly is related to self-reported anxiety and if changes in self-reported anxiety are related to changes in heart rate.

METHODS

We measured overground preferred walking speed, oxygen consumption rate and heart rates during rest and walking, and self-reported anxiety in 10 elderly (mean age 69.5 ± 3.1 years, 8 males and 2 females). At their preferred speed, the participants first walked overground, then on a high treadmill, and then on a low treadmill. Gross and Net metabolic costs of walking were calculated from the rates of oxygen consumption.

RESULTS

Gross and net metabolic cost of walking were higher (p < 0.05) on high treadmill (net cost: 2.64 J kg^-1 m^-1) and low treadmill (net cost: 2.68 J kg^-1 m^-1) compared to overground (net cost: 2.44 J kg^-1 m^-1), and the same was true for heart rate. There were no significant differences (p > 0.05) in metabolic costs and heart rates between the two treadmill conditions. Self-reported anxiety was higher on the high treadmill compared to overground (p = 0.004) and compared to low treadmill (p = 0.02). We found no significant difference (p > 0.05) for self-reported anxiety between overground and the low treadmill.

CONCLUSION

These results show that treadmill walking cannot be adequately generalized to overground walking. The differences found in metabolic cost on treadmills compared to overground were not related to differences in self-reported anxiety. Furthermore, the changes in heart rate are not related to changes in self-reported anxiety.

User-centered design of feedback regarding health-related behaviors derived from wearables: An approach targeting older adults and persons living with neurodegenerative disease

Objective

There has been tremendous growth in wearable technologies for health monitoring but limited efforts to optimize methods for sharing wearables-derived information with older adults and clinical cohorts. This study aimed to co-develop, design and evaluate a personalized approach for information-sharing regarding daily health-related behaviors captured with wearables.

Methods

A participatory research approach was adopted with: (a) iterative stakeholder, and evidence-led development of feedback reporting; and (b) evaluation in a sample of older adults (n  =  15) and persons living with neurodegenerative disease (NDD) (n  =  25). Stakeholders included persons with lived experience, healthcare providers, health charity representatives and individuals involved in aging/NDD research. Feedback report information was custom-derived from two limb-mounted inertial measurement units and a mobile electrocardiography device worn by participants for 7-10 days. Mixed methods were used to evaluate reporting 2 weeks following delivery. Data were summarized using descriptive statistics for the group and stratified by cohort and cognitive status.

Results

Participants (n  =  40) were 60% female (median 72 (60-87) years). A total of 82.5% found the report easy to read or understand, 80% reported the right amount of information was shared, 90% found the information helpful, 92% shared the information with a family member or friend and 57.5% made a behavior change. Differences emerged in sub-group comparisons. A range of participant profiles existed in terms of interest, uptake and utility.

Conclusions

The reporting approach was generally well-received with perceived value that translated into enhanced self-awareness and self-management of daily health-related behaviors. Future work should examine potential for scale, and the capacity for wearables-derived feedback to influence longer-term behavior change.

Daily step volume and intensity moderate the association of sedentary time and cardiometabolic disease risk in community-dwelling older adults: A cross-sectional study

OBJECTIVE

To investigate the moderating effect of step count and peak cadence on the relationship of sedentary time and cardiometabolic disease risk in community-dwelling older adults.

METHODS

This cross-sectional study included 248 older adults aged 60-80 years without cardiovascular disease (66.0 ± 4.6 years of age; 78 % females). Sedentary time, step count and peak cadence were measured by a hip-worn accelerometer for seven days. Peak cadence was defined as the average of 30 min of the day (but not necessarily consecutive) with the highest cadence (steps per minute) for all valid days. Cardiometabolic disease risk was defined using a sex-specific continuous metabolic syndrome score (cMetS). Sedentary time was used as an explanatory variable for cMetS and step count and peak cadence as moderators. The analyses were adjusted for known cardiometabolic disease risk factors and accelerometer wear time. The Johnson-Neyman technique was used to specify the value of moderator variables at which the significant relationship between sedentary time and cMetS disappears.

RESULTS

Both step count (β = -0.186, P = 0.032) and peak cadence (β = -0.003, P = 0.007) showed a moderating effect on the relationship of sedentary time and cMetS. The association of sedentary time and cMetS was not statistically significant (p > 0.05) when step count or peak cadence exceed 5715 steps per day and 57 steps per minute, respectively.

CONCLUSION

Steps per day and peak cadence moderate the association of sedentary time and cardiometabolic disease risk in older adults. Therefore, steps per day and peak cadence seem to offset the deleterious effects of sedentary time on cardiometabolic health in this population.

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.

Relationships Between Physical Activity Metrics of Intensity and Diabetes

INTRODUCTION

Physical activity (PA) prevents diabetes-associated complications. Little is known about what constitutes effective PA interventions to mitigate diabetes. Identifying PA metrics associated with the efficacy of PA interventions will provide insight into devising strategies to treat diabetes.

PURPOSE

The aim of this study was to analyze the relationships between preclinical and postclinical variables from a 10-week intervention designed to increase PA in adults with diabetes.

METHODS

A secondary analysis was performed to evaluate data using Wilcoxon rank sum test, permutation test and Spearman correlation to analyze hemoglobin A1c (HbA1c), weight, and PA metrics (maximum steps per episode, cadence, daily steps, and 6-minute walk).

RESULTS

Poststudy HbA1c level was associated with maximum steps (r = -0.63, P = .03) and 6-minute walk (r = -0.50, P = .09). Baseline weight was associated with average cadence (r = -0.76, P = .007), and poststudy weight was associated with average cadence (r = -0.60, P = .041) and maximum steps (r = -0.62, P = .03).

CONCLUSIONS

Cadence and maximum steps per episode reflect PA intensity and were associated with HbA1c and weight in adults with diabetes.

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.

Smartphone-Based Gait Cadence to Identify Older Adults with Decreased Functional Capacity

<b><i>Background:</i></b> Functional capacity assessment is a critical step in the preoperative evaluation to identify patients at increased risk of cardiac complications and disability after major noncardiac surgery. Smartphones offer the potential to objectively measure functional capacity but are limited by inaccuracy in patients with poor functional capacity. Open-source methods exist to analyze accelerometer data to estimate gait cadence (steps/min), which is directly associated with activity intensity. Here, we used an updated Step Test smartphone application with an open-source method to analyze accelerometer data to estimate gait cadence and functional capacity in older adults. <b><i>Methods:</i></b> We performed a prospective observational cohort study within the Frailty, Activity, Body Composition and Energy Expenditure in Aging study at the University of Chicago. Participants completed the Duke Activity Status Index (DASI) and performed an in-clinic 6-min walk test (6MWT) while using the Step Test application on a study smartphone. Gait cadence was measured from the raw accelerometer data using an adaptive empirical pattern transformation method, which has been previously validated. A 6MWT distance of 370 m was used as an objective threshold to identify patients at high risk. We performed multivariable logistic regression to predict walking distance using a priori explanatory variables. <b><i>Results:</i></b> Sixty patients were enrolled in the study. Thirty-seven patients completed the protocol and were included in the final data analysis. The median (IQR) age of the overall cohort was 71 (69–74) years, with a body mass index of 31 (27–32). There were no differences in any clinical characteristics or functional measures between participants that were able to walk 370 m during the 6MWT and those that could not walk that distance. Median (IQR) gait cadence for the entire cohort was 110 (102–114) steps/min during the 6MWT. Median (IQR) gait cadence was higher in participants that walked more than 370 m during the 6MWT 112 (108–118) versus 106 (96–114) steps/min; <i>p</i> = 0.0157). The final multivariable model to identify participants that could not walk 370 m included only median gait cadence. The Youden’s index cut-point was 107 steps/min with a sensitivity of 0.81 (95% CI: 0.77, 0.85) and a specificity of 0.57 (95% CI: 0.55, 0.59) and an AUCROC of 0.69 (95% CI: 0.51, 0.87). <b><i>Conclusions:</i></b> Our pilot study demonstrates the feasibility of using gait cadence as a measure to estimate functional capacity. Our study was limited by a smaller than expected sample size due to COVID-19, and thus, a prospective study with preoperative patients that measures outcomes is necessary to validate our findings.

The impact of different step rate threshold methods on physical activity intensity in older adults

BACKGROUND

Older adults benefit most from engaging in higher-intensity physical activity, which is often determined using step rate thresholds. Fixed step rate thresholds that correspond to moderate (MPA) and vigorous-intensity physical activity (VPA) have been developed for heuristic activity promotion. The activPAL monitor uses step rate thresholds to determine activity intensity. Stepping thresholds may also vary based on body mass index (BMI) or aerobic fitness level in older adults. Despite the various thresholds used in the literature, it is unclear whether they produce similar outcomes.

RESEARCH QUESTION

How does time spent in physical activity intensities compare between different step rate thresholds in older adults?

METHODS

Thirty-eight participants (24♀; 67 ± 4 years; BMI: 26.6 ± 4.4 kg/m²) wore an activPAL monitor 24-hr/day for up to 7-d (total: 205-d). Aerobic fitness (V̇O₂max: 23 ± 8 ml/kg/min) was determined via indirect calorimetry during a maximal, graded cycling test. Time spent in each intensity category (light-physical-activity [LPA], MPA, VPA) was determined using the fixed (MPA/VPA) 100/130, 110/130, and activPAL step rate thresholds (74/212), as well as BMI-adjusted absolute (108.5 ± 2.5/134.0 ± 4.8) and BMI-adjusted relative (40%/60% V̇O₂max; 111.4 ± 14.7/132.0 ± 19.0) cut-offs. Times spent in each intensity category were compared between methods.

RESULTS

The activPAL and 100/130 thresholds yielded less LPA and more MPA than all other methods. The activPAL had no time spent in VPA at all. The BMI-adjusted absolute and relative thresholds produced statistically equivalent time in LPA and MPA (via equivalence testing), but not VPA. No two methods yielded similar time spent in LPA, MPA, or VPA.

SIGNIFICANCE

The choice of step rate threshold has a major impact on physical activity intensity outcomes in older adults. Inherently, strategies that adjust for older adults' body size and/or aerobic fitness level provide a more individualized data processing strategy than fixed thresholds that assume the same threshold for all older adults.

Mediating effect of muscle power on the relationship of physical activity with physical fitness and physical function in older women

OBJECTIVE

This study analyzed if the associations of physical activity with physical fitness and physical function in older women are mediated by muscle power.

METHODS

Participants were 54 older women (age 73.5 ± 6.8 yrs). Moderate-to-vigorous intensity physical activity (min day^-1) was measured by accelerometry. Lower limb muscle power (W/kg) was estimated from a single two-leg countermovement jump performed on a force platform. Physical fitness (lower body strength, agility/dynamic balance, and aerobic endurance) was objectively assessed through the Senior Fitness Test Battery, respectively: 30s chair stand (repetitions), 8-ft up-and-go (s), and 6-min walk test (m). Physical function was subjectively evaluated via the 12-item Composite Physical Function Scale Questionnaire (score). Mediation effects were estimated using bootstrapped 95% confidence intervals and were deemed significant if 0 was not included in the intervals.

RESULTS

Mediation analysis controlling to age revealed an indirect effect of moderate-to-vigorous intensity physical activity through muscle power on all physical fitness components, specifically lower body strength (B = 0.048, 95% BootCI [0.013, 0.114]), agility/dynamic balance (B = -0.009, 95% BootCI [-0.024, -0.002]) and aerobic endurance (B = 0.656, 95% BootCI [0.142, 1.597]) and on physical function global score (B = 0.040 95% BootCI [0.009, 0.094]).

CONCLUSIONS

These results suggest that physical activity of at least moderate intensity is relevant to daily functional competence, by promoting the maintenance or improvement of muscle power.