Walking economy is predictably determined by speed, grade, and gravitational load.

The metabolic energy that human walking requires can vary by more than 10-fold, depending on the speed, surface gradient, and load carried. Although the mechanical factors determining economy are generally considered to be numerous and complex, we tested a minimum mechanics hypothesis that only three variables are needed for broad, accurate prediction: speed, surface grade, and total gravitational load. We first measured steady-state rates of oxygen uptake in 20 healthy adult subjects during unloaded treadmill trials from 0.4 to 1.6 m/s on six gradients: -6, -3, 0, 3, 6, and 9°. Next, we tested a second set of 20 subjects under three torso-loading conditions (no-load, +18, and +31% body weight) at speeds from 0.6 to 1.4 m/s on the same six gradients. Metabolic rates spanned a 14-fold range from supine rest to the greatest single-trial walking mean (3.1 ± 0.1 to 43.3 ± 0.5 ml O2·kg-body-1·min-1, respectively). As theorized, the walking portion (V̇o2-walk = V̇o2-gross - V̇o2-supine-rest) of the body's gross metabolic rate increased in direct proportion to load and largely in accordance with support force requirements across both speed and grade. Consequently, a single minimum-mechanics equation was derived from the data of 10 unloaded-condition subjects to predict the pooled mass-specific economy (V̇o2-gross, ml O2·kg-body + load-1·min-1) of all the remaining loaded and unloaded trials combined (n = 1,412 trials from 90 speed/grade/load conditions). The accuracy of prediction achieved (r2 = 0.99, SEE = 1.06 ml O2·kg-1·min-1) leads us to conclude that human walking economy is predictably determined by the minimum mechanical requirements present across a broad range of conditions.NEW & NOTEWORTHY Introduced is a "minimum mechanics" model that predicts human walking economy across a broad range of conditions from only three variables: speed, surface grade, and body-plus-load mass. The derivation/validation data set includes steady-state loaded and unloaded walking trials (n = 3,414) that span a fourfold range of walking speeds on each of six different surface gradients (-6 to +9°). The accuracy of our minimum mechanics model (r2 = 0.99; SEE = 1.06 ml O2·kg-1·min-1) appreciably exceeds that of currently used standards.

Associations between active living-oriented zoning and no adult leisure-time physical activity in the U.S.

Nearly one-third of adults report no leisure-time physical activity (LTPA). Governmental and authoritative bodies recognize the role that community design through zoning code changes can play in enabling LTPA. This study examined the association between zoning and no adult LTPA in the U.S. This study was conducted between 2012 and 2016, with analyses occurring in 2015-2016. Zoning codes effective as of 2010 were compiled for jurisdictions located in the 495 most populous U.S. counties and were evaluated for pedestrian-oriented code reform zoning, 11 active living-oriented provisions (e.g., sidewalks, bike-pedestrian connectivity, mixed use, bike lanes) and a summated zoning scale (max=12). Individual-level LTPA data were obtained from the 2012 CDC Behavioral Risk Factor Surveillance System (BRFSS). County-aggregated, population-weighted zoning variables were constructed for linking to BRFSS. Log-log multivariate regressions (N=147,517 adults), controlling for individual and county characteristics and with robust standard errors clustered on county, were conducted to examine associations between zoning and no LTPA. Relative risks (RR) compared predicted lack of LTPA at 0% and 100% county-level population exposure to each zoning predictor. Zoning code reforms were associated with a 13% lower probability of no LTPA (RR: 0.87, 95% CI: 0.82-0.92). Except for crosswalks, all zoning provisions were associated with an 11-16% lower probability of no LTPA. Having all 12 zoning provisions was associated with a 22% lower probability of no LTPA (RR: 0.78, 95% CI: 0.72-0.83). The results suggest that active living-oriented zoning is a policy lever available to communities seeking to reduce rates of no LTPA.

The Walking Suitability Index of the Territory (T-WSI): a new tool to evaluate urban neighborhood walkability.

AIM: To design an easy method to evaluate the walkability of an urban neighborhood, in order to support Public Administrations in the decision making related to urban health policy and local development. METHODS: The tool, called the Walking Suitability Index of the territory (T-WSI), has been further developed by our team. T-WSI is applied to each street of an environmental area. It includes 12 indicators subdivided into 4 categories: practicability, safety, urbanity, pleasurableness. Data collected in each street are inserted in an algoritm to perform weighted sums and to aggregate the indicators and the categories, up to compute the final index. To validate T-WSI an experimental study was carried out in two environmental areas of Rome: "San Saba" and "Sacco Pastore". RESULTS: The average index is: 58.6 for the neighborhood "San Saba" and for 55.1 for "Sacco Pastore. Both results detected gaps in the design for pedestrian use of public spaces. Among the analysed categories, Safety showed the worst results in both neighborhoods, mainly for the lack of "protection from vehicle speed". CONCLUSIONS: The developed tool is easy to use, inexpensive, sensible and reproducible, offering a good basis for urban health policy decisions. The relevance of the tool stands on the survey methodology, based on the direct and objective observation of the context.

Normative values of cognitive and physical function in older adults: findings from the Irish Longitudinal Study on Ageing.

OBJECTIVES: To provide normative values of tests of cognitive and physical function based on a large sample representative of the population of Ireland aged 50 and older. DESIGN: Data were used from the first wave of The Irish Longitudinal Study on Ageing (TILDA), a prospective cohort study that includes a comprehensive health assessment. SETTING: Health assessment was undertaken at one of two dedicated health assessment centers or in the study participant's home if travel was not practicable. PARTICIPANTS: Five thousand eight hundred ninety-seven members of a nationally representative sample of the community-living population of Ireland aged 50 and older. Those with severe cognitive impairment, dementia, or Parkinson's disease were excluded. MEASUREMENTS: Measurements included height and weight, normal walking speed, Timed Up-and-Go, handgrip strength, Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Color Trails Test, and bone mineral density. Normative values were estimated using generalized additive models for location shape and scale (GAMLSS) and are presented as percentiles, means, and standard deviations. RESULTS: Generalized additive models for location shape and scale fit the observed data well for each measure, leading to reliable estimates of normative values. Performance on all tasks decreased with age. Educational attainment was a strong determinant of performance on all cognitive tests. Tests of walking speed were dependent on height. Distribution of body mass index did not change with age, owing to simultaneous declines in weight and height. CONCLUSION: Normative values were found for tests of many aspects of cognitive and physical function based on a representative sample of the general older Irish population.

Staging of mobility, transfer and walking functions of elderly persons based on the codes of the International Classification of Functioning, Disability and Health.

BACKGROUND: The International Classification of Functioning, Disability and Health (ICF) was introduced by the World Health Organization as a common taxonomy to describe the burden of health conditions. This study focuses on the development of a scale for staging basic mobility and walking functions based on the ICF. METHODS: Thirty-three ICF codes were selected to test their fit to the Rasch model and their location. Of these ICF items, four were used to develop a Guttman- type scale of "basic mobility" and another four to develop a"walking" scale to stage functional performance in the elderly. The content validity and differential item functioning of the scales were assessed. The participants, chosen at random, were Japanese over 65 years old using the services of public long-term care insurance, and whose functional assessments were used for scale development and scale validation. RESULTS: There were 1164 elderly persons who were eligible for scale development. To stage the functional performance of elderly persons, two Guttman-type scales of "basic mobility" and "walking" were constructed. The order of item difficulty was validated using 3260 elderly persons. There is no differential item functioning about study location, sex and age-group in the newly developed scales. These results suggested the newly developed scales have content validity. CONCLUSIONS: These scales divided functional performance into five stages according to four ICF codes, making the measurements simple and less time-consuming and enable clear descriptions of elderly functioning level. This was achieved by hierarchically rearranging the ICF items and constructing Guttman-type scales according to item difficulty using the Rasch model. In addition, each functional level might require similar resources and therefore enable standardization of care and rehabilitation. Illustrations facilitate the sharing of patient images among health care providers. By using the ICF as a common taxonomy, these scales could be used internationally as assessment scales in geriatric care settings. However these scales require further validity and reliability studies for international application.

Workplace nutrition and physical activity promotion at Liverpool Hospital.

ISSUE ADDRESSED: The workplace is an effective way of reaching large numbers of adults during working hours, and increasing physical activity, promoting healthy eating or both.This paper evaluates the effectiveness of a workplace intervention in a hospital setting in Australia. METHODS: A 12-week program was conducted with 399 employees of Liverpool Hospital, NSW, to increase physical activity and healthy eating. Participants received a pedometer, healthy cookbook, water bottle, sandwich container and Measure Up campaign resources. A web-based survey was completed at baseline and follow up. RESULTS: Sixty-six per cent of participants completed the follow-up survey. Those that did not complete the follow-up evaluation were not significantly different to completers. Respondents reported a significant increase in median minutes walked to 200 minutes and in vigorous physical activity to 85 minutes over the previous week. Participants consuming adequate fruit and vegetable per day increased by 24.7% and 22.7%, respectively. More participants also consumed breakfast on seven days of the week and consumed one or more litres of water per day. CONCLUSIONS: The intervention was successful for the participants. With some improvements to processes, we encourage further similar programs with the health sector workforce.