Pedometer-Determined Step Count Guidelines for Classifying Walking Intensity in a Young Ostensibly Healthy Population

2005 ◽  
Vol 30 (6) ◽  
pp. 666-676 ◽  
Author(s):  
Catrine Tudor-Locke ◽  
Susan B. Sisson ◽  
Tracy Collova ◽  
Sarah M. Lee ◽  
Pamela D. Swan
Keyword(s):  
Steady State ◽  
Cross Validation ◽  
Moderate Intensity ◽  
Healthy Population ◽  
Test Results ◽  
Ambulatory Activity ◽  
Cut Points ◽  
State Formula ◽  
Moderate Intensity Activity ◽  
All Speeds

Purpose: (a) To establish pedometer steps/min intensity categories (i.e., light, moderate, hard, very hard) for adults under controlled conditions, and (b) use these cut-points to ascertain the number of steps expected in 30 minutes of moderate intensity activity. Methods: 25 men and 25 women, ages 18-39 years, performed 6-min exercise bouts at 3 treadmill speeds (4.8, 6.4, and 9.7 km/hr). Yamax SW-200 pedometers indicated steps, and steady-state [Formula: see text] was recorded. METs were calculated by dividing steady-state [Formula: see text] by 3.5 ml•kg−1 min−1. Linear regression was used to quantify the relationships between steps/min and METs across all speeds. Ten participants (5 M, 5 F) were randomly selected from the original 50 and constituted a holdout sample for cross-validation purposes (i.e, comparing actual and predicted METs; paired t-test). Results: The regression equation for males was: METs = −7.065 + (0.105*steps/min) r2 = 0.803. For females it was: METs = −8.805 + (0.110*steps/min) r2 = 0.830. Cross-validation was confirmed. Conclusions: Pedometer cut-points corresponding to minimal moderate intensity walking were 96 steps/min in men and 107 steps/min in women, or roughly 100 steps/min for both. This translates to approximately 3,000 steps in 30 min of moderate-intensity ambulatory activity for both genders. Key words: exercise, outcome assessment, motion sensor

scholarly journals Calibration and Cross-Validation of Accelerometery for Estimating Movement Skills in Children Aged 8–12 Years

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2776 ◽  
Author(s):  
Michael J. Duncan ◽  
Alexandra Dobell ◽  
Mark Noon ◽  
Cain C. T. Clark ◽  
Clare M. P. Roscoe ◽  
...  
Keyword(s):  
Sedentary Behaviour ◽  
Motor Skills ◽  
Cross Validation ◽  
Moderate Intensity ◽  
Roc Curve Analysis ◽  
Independent Dataset ◽  
Object Control ◽  
Cut Points ◽  
Accelerometer Cut Points ◽  
Children’S Physical Activity

(1) Background: This study sought to calibrate triaxial accelerometery, worn on both wrists, waist and both ankles, during children’s physical activity (PA), with particular attention to object control motor skills performed at a fast and slow cadence, and to cross-validate the accelerometer cut-points derived from the calibration using an independent dataset. (2) Methods: Twenty boys (10.1 ±1.5 years) undertook seven, five-minute bouts of activity lying supine, standing, running (4.5kmph−1) instep passing a football (fast and slow cadence), dribbling a football (fast and slow cadence), whilst wearing five GENEActiv accelerometers on their non-dominant and dominant wrists and ankles and waist. VO2 was assessed concurrently using indirect calorimetry. ROC curve analysis was used to generate cut-points representing sedentary, light and moderate PA. The cut-points were then cross-validated using independent data from 30 children (9.4 ± 1.4 years), who had undertaken similar activities whilst wearing accelerometers and being assessed for VO2. (3) Results: GENEActiv monitors were able to discriminate sedentary activity to an excellent level irrespective of wear location. For moderate PA, discrimination of activity was considered good for monitors placed on the dominant wrist, waist, non-dominant and dominant ankles but fair for the non-dominant wrist. Applying the cut-points to the cross-validation sample indicated that cut-points validated in the calibration were able to successfully discriminate sedentary behaviour and moderate PA to an excellent standard and light PA to a fair standard. (4) Conclusions: Cut-points derived from this calibration demonstrate an excellent ability to discriminate children’s sedentary behaviour and moderate intensity PA comprising motor skill activity.

scholarly journals Impact of ActiGraph Sampling Rate and Intermonitor Comparability on Measures of Physical Activity in Adults

2021 ◽  
pp. 1-11
Author(s):  
Kimberly A. Clevenger ◽  
Jan Christian Brønd ◽  
Daniel Arvidsson ◽  
Alexander H.K. Montoye ◽  
Kelly A. Mackintosh ◽  
...  
Keyword(s):  
Physical Activity ◽  
Sampling Rate ◽  
Mean Amplitude ◽  
Moderate Intensity ◽  
Equivalence Testing ◽  
Cut Points ◽  
Activity Intensity ◽  
Moderate Intensity Activity ◽  
Mean Differences ◽  
Vector Magnitude

Background: ActiGraph is a commonly used, research-grade accelerometer brand, but there is little information regarding intermonitor comparability of newer models. In addition, while sampling rate has been shown to influence accelerometer metrics, its influence on measures of free-living physical activity has not been directly studied. Purpose: To examine differences in physical activity metrics due to intermonitor variability and chosen sampling rate. Methods: Adults (n = 20) wore two hip-worn ActiGraph wGT3X-BT monitors for 1 week, with one accelerometer sampling at 30 Hz and the other at 100 Hz, which was downsampled to 30 Hz. Activity intensity was classified using vector magnitude, Euclidean Norm Minus One (ENMO), and mean amplitude deviation (MAD) cut points. Equivalence testing compared outcomes. Results: There was a lack of intermonitor equivalence for ENMO, time in sedentary/light- or moderate-intensity activity according to ENMO cut points, and time in moderate-intensity activity according to MAD cut points. Between sampling rates, differences existed for time in moderate-intensity activity according to vector magnitude, ENMO, and MAD cut points, and time in sedentary/light-intensity activity according to ENMO cut points. While mean differences were small (0.1–1.7 percentage points), this would equate to differences in moderate-to vigorous-intensity activity over a 10-hr wear day of 3.6 (MAD) to 10.8 (ENMO) min/day for intermonitor comparisons or 3.6 (vector magnitude) to 5.4 (ENMO) min/day for sampling rate. Conclusions: Epoch-level intermonitor differences were larger than differences due to sampling rate, but both may impact outcomes such as time spent in each activity intensity. ENMO was the least comparable metric between monitors or sampling rates.

Cross-validation of pedometer-determined cut-points for healthy weight in British children from White and South Asian backgrounds

2014 ◽  
Vol 41 (5) ◽  
pp. 389-394 ◽  
Author(s):  
Michael J. Duncan ◽  
Emma L. J. Eyre ◽  
Elizabeth Bryant ◽  
Samantha L. Birch
Keyword(s):  
South Asian ◽  
Cross Validation ◽  
Healthy Weight ◽  
Cut Points ◽  
British Children

Engine Testing of an Advanced Alloy for Microturbine Primary Surface Recuperators

2005 ◽  
Author(s):  
Wendy J. Matthews ◽  
Terry Bartel ◽  
Dwaine L. Klarstrom ◽  
Larry R. Walker
Keyword(s):  
Steady State ◽  
Oxide Scale ◽  
Engine Test ◽  
Test Results ◽  
Protective Oxide ◽  
Protective Oxide Scale ◽  
Cyclic Operation ◽  
Engine Testing

HAYNES® alloy HR-120® has been identified as a potential alloy for the manufacture of primary surface recuperators. Primary surface recuperator components have been manufactured from HR-120, and actual microturbine testing is on going. Initial engine test results indicate the formation of a protective oxide scale that is resistant to both steady-state and cyclic operation with no evidence of accelerated attack, and which is likely to meet or exceed the desired 80,000 hour component life.

Assessment of the MyWellness Key accelerometer in people with type 2 diabetes

2015 ◽  
Vol 40 (11) ◽  
pp. 1193-1198 ◽  
Author(s):  
Samantha Kate McGinley ◽  
Marni J. Armstrong ◽  
Farah Khandwala ◽  
Silvano Zanuso ◽  
Ronald J. Sigal
Keyword(s):  
Type 2 Diabetes ◽  
Normal Weight ◽  
Moderate Intensity ◽  
Exercise Session ◽  
Free Living ◽  
The Mean ◽  
Moderate Intensity Activity ◽  
The Right ◽  
Treadmill Protocol

Accelerometers are designed to measure physical activity (PA) objectively. The MyWellness Key (MWK) accelerometer has been validated primarily in younger, normal-weight populations. The aims of this study were to examine the accuracy of the MWK against directly measured lab-based exercise and free-living PA in people with type 2 diabetes, many of whom are older and overweight or obese. Thirty-five participants with type 2 diabetes completed the protocol, which included a laboratory-based session and a free-living phase. In the laboratory visit, participants completed a structured treadmill protocol wearing MWKs on each hip (all subjects) and bra cup (women only). The speed where each MWK switched from recording light- to moderate-intensity activity was determined for each MWK worn. In the free-living phase, participants wore the MWK for all waking hours for 2 weeks, and recorded exercise in PA diaries immediately after each exercise session. The mean cut-points between low (“Free”) and moderate (“Play”) intensity for the right and left waist-worn MWKs were 4.1 ± 0.5 km/h and 5.0 ± 0.9 km/h for the bra-mounted MWK; ideal cut-point would be 4.0 km/h. In the free-living phase, the Spearman correlation between PA according to PA diary and the waist-worn MWK was 0.81 (95% confidence interval (CI): 0.76, 0.85; P < 0.001), but only 0.66 (95% CI: 0.53, 0.77; P < 0.001) when on the bra. In conclusion, the waist-worn MWK measured PA volume accurately, and was acceptably accurate at discriminating between low- and moderate-intensity PA in people with type 2 diabetes. The MWK underestimated PA volume and intensity when worn on a bra.

Respiration in Exercising Fowl. III. Ventilation

1982 ◽  
Vol 96 (1) ◽  
pp. 315-324
Author(s):  
J. H. BRACKENBURY ◽  
M. GLEESON ◽  
P. AVERY
Keyword(s):  
Steady State ◽  
State Level ◽  
Minute Volume ◽  
Oxygen Extraction ◽  
Respiratory Pattern ◽  
Heavy Exercise ◽  
Predominant Role ◽  
Air Temperatures ◽  
Maximum Work ◽  
All Speeds

1. Minute volume (V), respiratory frequency (f) and tidal volume (VT) were continuously measured in domestic fowl running on a treadmill at speeds of 1.24–4.3 km h−1 in air temperatures of 18±2 °C and 35±2 °C. Oxygen extraction (E) was estimated using previously measured values of oxygen consumption. 2. At 18±2 °C V, f and VT rose abruptly at the start of exercise and V and f continued to rise except at the slower running speeds. V and f continued to rise throughout exercise at all speeds in the heat-stressed birds. In both groups VT reached a maximum at the start of exercise then fell to a new steady-state level. Steady-state V, f and VT increased with exercise speed at 18±2 °C. At 35–37 °C steady-state V and VT increased with speed but f changed relatively little. 3. E remained close to resting (0.21) at low speeds in room temperatures but decreased to 0.17 at 4.3 km h−1. In contrast E rose from 0.05 at rest in heat-stressed birds to 0.14 at 3.6 km h−1. The changes in oxygen extraction and respiratory pattern in the two groups during exercise are discussed in connexion with the control of ventilation by thermal and non-thermal factors. It is suggested that the latter play a predominant role during heavy exercise and that this accounts for the convergence of respiratory patterns in both heat-stressed and non heat-stressed birds at maximum work rates.

Transient changes in muscle high-energy phosphates during moderate exercise

1993 ◽  
Vol 75 (2) ◽  
pp. 648-656 ◽  
Author(s):  
G. D. Marsh ◽  
D. H. Paterson ◽  
J. J. Potwarka ◽  
R. T. Thompson
Keyword(s):  
Oxygen Consumption ◽  
Steady State ◽  
Recovery Period ◽  
High Energy ◽  
Second Order ◽  
Moderate Intensity ◽  
High Energy Phosphates ◽  
Order Model ◽  
Time Constants ◽  
First Order

The purpose of this study was to use 31P-nuclear magnetic resonance spectroscopy to examine changes in wrist flexor muscle metabolism during the transitions from rest to steady-state exercise (on-transient) and back to rest (off-transient). Five healthy young males (mean age 25 +/- 2 yr) performed a series of square-wave exercise tests, each consisting of 5 min of moderate-intensity work followed by a 5-min recovery period. The subjects repeated this protocol six times, and each individual's results were pooled before analysis. ATP and intracellular pH did not change significantly during exercise or recovery. Phosphocreatine (PCr) declined progressively at the onset of exercise, reaching a plateau after approximately 2 min. A reciprocal increase in Pi occurred during the onset of exercise. During the recovery period PCr was resynthesized, whereas Pi returned to resting levels. The data were plotted as a function of time and fit with both first- and second-order exponential growth or decay models; however, the second-order model did not significantly improve the fit of the data. Time constants for the first-order model of the on- and off-transient responses for both PCr and Pi were approximately 30 s. These values are nearly identical to the time constants for oxygen consumption during submaximal exercise that have been reported previously by several authors. The results of this study show that the metabolism of muscle PCr during steady-state exercise and recovery can be accurately described by a monoexponential model and, further, suggest that a first-order proportionality exists between metabolic substrate utilization and oxygen consumption.

scholarly journals Personalized Reference Intervals in Laboratory Medicine: A New Model Based on Within-Subject Biological Variation

2020 ◽  
Author(s):  
Abdurrahman Coşkun ◽  
Sverre Sandberg ◽  
Ibrahim Unsal ◽  
Coskun Cavusoglu ◽  
Mustafa Serteser ◽  
...  
Keyword(s):  
Steady State ◽  
Personalized Medicine ◽  
Clinical Chemistry ◽  
Reference Interval ◽  
Reference Intervals ◽  
Biological Variation ◽  
Test Results ◽  
Steady State Condition ◽  
Laboratory Test Results ◽  
Measurement Results

Abstract Background The concept of personalized medicine has received widespread attention in the last decade. However, personalized medicine depends on correct diagnosis and monitoring of patients, for which personalized reference intervals for laboratory tests may be beneficial. In this study, we propose a simple model to generate personalized reference intervals based on historical, previously analyzed results, and data on analytical and within-subject biological variation. Methods A model using estimates of analytical and within-subject biological variation and previous test results was developed. We modeled the effect of adding an increasing number of measurement results on the estimation of the personal reference interval. We then used laboratory test results from 784 adult patients (&gt;18 years) considered to be in a steady-state condition to calculate personalized reference intervals for 27 commonly requested clinical chemistry and hematology measurands. Results Increasing the number of measurements had little impact on the total variation around the true homeostatic set point and using ≥3 previous measurement results delivered robust personalized reference intervals. The personalized reference intervals of the study participants were different from one another and, as expected, located within the common reference interval. However, in general they made up only a small proportion of the population-based reference interval. Conclusions Our study shows that, if using results from patients in steady state, only a few previous test results and reliable estimates of within-subject biological variation are required to calculate personalized reference intervals. This may be highly valuable for diagnosing patients as well as for follow-up and treatment.

scholarly journals Dynamics of middle cerebral artery blood flow velocity during moderate-intensity exercise

2017 ◽  
Vol 122 (5) ◽  
pp. 1125-1133 ◽  
Author(s):  
Sandra A. Billinger ◽  
Jesse C. Craig ◽  
Sarah J. Kwapiszeski ◽  
Jason-Flor V. Sisante ◽  
Eric D. Vidoni ◽  
...  
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Dynamic Response ◽  
Moderate Intensity ◽  
Artery Blood Flow ◽  
Moderate Intensity Exercise ◽  
Cerebrovascular Function ◽  
Exercise Response ◽  
Response Profile ◽  
Health And Disease

The dynamic response to a stimulus such as exercise can reveal valuable insights into systems control in health and disease that are not evident from the steady-state perturbation. However, the dynamic response profile and kinetics of cerebrovascular function have not been determined to date. We tested the hypotheses that bilateral middle cerebral artery blood flow mean velocity (MCAV) increases exponentially following the onset of moderate-intensity exercise in 10 healthy young subjects. The MCAV response profiles were well fit to a delay (TD) + exponential (time constant, τ) model with substantial agreement for baseline [left (L): 69, right (R): 64 cm/s, coefficient of variation (CV) 11%], response amplitude (L: 16, R: 13 cm/s, CV 23%), TD (L: 54, R: 52 s, CV 9%), τ (L: 30, R: 30 s, CV 22%), and mean response time (MRT) (L: 83, R: 82 s, CV 8%) between left and right MCAV as supported by the high correlations (e.g., MRT r = 0.82, P < 0.05) and low CVs. Test-retest reliability was high with CVs for the baseline, amplitude, and MRT of 3, 14, and 12%, respectively. These responses contrasted markedly with those of three healthy older subjects in whom the MCAV baseline and exercise response amplitude were far lower and the kinetics slowed. A single older stroke patient showed baseline ipsilateral MCAV that was lower still and devoid of any exercise response whatsoever. We conclude that kinetics analysis of MCAV during exercise has significant potential to unveil novel aspects of cerebrovascular function in health and disease. NEW & NOTEWORTHY Resolution of the dynamic stimulus-response profile provides a greater understanding of the underlying the physiological control processes than steady-state measurements alone. We report a novel method of measuring cerebrovascular blood velocity (MCAv) kinetics under ecologically valid conditions from rest to moderate-intensity exercise. This technique reveals that brain blood flow increases exponentially following the onset of exercise with 1) a strong bilateral coherence in young healthy individuals, and 2) a potential for unique age- and disease-specific profiles.

scholarly journals Using Accelerometers in Youth Physical Activity Studies: A Review of Methods

2013 ◽  
Vol 10 (3) ◽  
pp. 437-450 ◽  
Author(s):  
Kelli L. Cain ◽  
James F. Sallis ◽  
Terry L. Conway ◽  
Delfien Van Dyck ◽  
Lynn Calhoon
Keyword(s):  
Physical Activity ◽  
Decision Rule ◽  
Decision Rules ◽  
Moderate Intensity ◽  
Accelerometer Data ◽  
Cut Points ◽  
Moderate Intensity Physical Activity ◽  
Youth Physical Activity ◽  
Intensity Physical Activity ◽  
Over Time

Background:In 2005, investigators convened by the National Cancer Institute recommended development of standardized protocols for accelerometer use and reporting decision rules in articles. A literature review was conducted to document accelerometer methods and decision rule reporting in youth physical activity articles from 2005−2010.Methods:Nine electronic databases identified 273 articles that measured physical activity and/or sedentary behavior using the most-used brand of accelerometer (ActiGraph). Six key methods were summarized by age group (preschool, children, and adolescents) and trends over time were examined.Results:Studies using accelerometers more than doubled from 2005−2010. Methods included 2 ActiGraph models, 6 epoch lengths, 6 nonwear definitions, 13 valid day definitions, 8 minimum wearing day thresholds, 12 moderate-intensity physical activity cut points, and 11 sedentary cut points. Child studies showed the most variation in methods and a trend toward more variability in cut points over time. Decision rule reporting improved, but only 54% of papers reported on all methods.Conclusion:The increasing diversity of methods used to process and score accelerometer data for youth precludes comparison of results across studies. Decision rule reporting is inconsistent, and trends indicate declining standardization of methods. A methodological research agenda and consensus process are proposed.

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