In the Everest valley of Nepal, because of the rugged mountain terrain, the ‘roads' are nothing more than dirt mountain footpaths. Most of the material is conveyed over long distances by professional porters who carry impressive burdens in a wicker basket supported by a strap looped over their head. We measured the body weight and loads carried by the Himalayan porters passing along the busy footpath to Namche Bazaar, the main market place of the Everest region. On average, the porters were carrying loads equivalent to 90% of their body weight on the last day of a 7-9 day trip covering a horizontal distance of ~100 km with >8000 m of total ascents and >6300 m of total descents. Interestingly, these porters adopt a specific rhythm of walking: they generally walk slowly and make very frequent rest stops using a T-stick or stone-platforms built along the trail to support the load during the pause. It has been shown that African women could carry head-supported loads more economically than Western subjects because they have developed a mechanical energy-saving strategy. Similarly, Nepalese porters could also have developed a mechanism to carry economically their very heavy loads. To test this hypothesis, we measured the energy consumption and the mechanical work done during level walking under different loading and speed conditions in the Nepali porters and in Western subjects. We compared these results to those of the African women. Nepalese porters carry loads at a lower cost than either the control subjects or the African women. For example, for a load equivalent to 60% of body weight, western Caucasian subjects increases their metabolic rate by 60%, the African women by 40% and the Nepalese porters by only 30%. Contrary to the African women who are taking advantage of the load to reduce the work performed, Nepalese porters do not modify their gait while carrying a load. Consequently, the mechanical work performed is not reduced as compared to control subjects walking at same speed-load combinations. Yet the Nepalese porters are the most economical load-carriers measured to date, particularly while carrying heavy loads at walking speeds slower than 1.4 m/s, but the exact mechanisms by which they save energy are still unknown. G. J. Bastien et al. Eur J Appl Physiol 94, 76 (2005); G. J. Bastien et al. Science 308, 1755 (2005); G. J. Bastien et al. J Exp Biol submitted.

The capability of estimating the walking direction of people would be useful in many applications such as those involving autonomous cars and robots. We introduce an approach for estimating the walking direction of people from images, based on learning the correct classification of a still image by using SVMs. We find that the performance of the system can be improved by classifying each image of a walking sequence and combining the outputs of the classifier. Experiments were performed to evaluate our system and estimate the trade-off between number of images in walking sequences and performance.

Objective: Pedometer programs are effective in increasing physical activity in sedentary individuals, a population that is at an increased for developing metabolic syndrome and each of its individual components. The aim of this study was to observe the effects of incremental increases in pedometer assessed physical activity on MetS components in sedentary overweight women. Design: This study was a longitudinal, quasi-experimental design. Participants were recruited from a 12-week work-site pedometer program and grouped after the intervention based on their self-paced increases in pedometer assessed physical activity with (a) active participants that increased their daily activity by mean volume >3000 steps/day or (b) participants who remained sedentary. Subjects: A multi-ethnic heterogeneous sample of seventy-seven sedentary middle-aged women (BMI: 30.15 plus or minus 5.24 kg/m2, age: 46.00 plus or minus 9.93 years). Measurements: Self-reported physical activity, pedometer assessed physical activity (steps/day), body mass index, resting heart rate, waist circumference, blood pressure, triglycerides, HDL-C and fasting glucose at baseline and after the 12-week program. Results: The active group showed significant within-group improvements (P less than or equal to .01) in waist circumference and fasting glucose. Significant between group changes were observed in resting heart rate (P less than or equal to .01), weight (P less than or equal to .01), BMI (P less than or equal to .01), and systolic blood pressure (P less than or equal to .001); however, the changes observed in systolic blood pressure were not independent of weight loss. Conclusions: Our study showed that incremental increases in steps/day over 12 weeks is effective in inducing mild, but favorable changes in some MetS components. This data suggests that this approach to increasing step/day is a viable starting point for sedentary individuals that may find it difficult to initially accumulate 10,000 steps/day.

This dissertation was designed to determine the effects of body mass index (BMI) and walking speed on activity monitor outputs. A secondary purpose was to compare the activity monitors’ performance in a free-living environment. In the first experiment, 71 participants wore three waist-mounted activity monitors (Actical, ActiGraph, and NL-2000) and an ankle-mounted device (StepWatch 3) while walking on a treadmill (40, 67 and 94 m/min). The tilt angle of each device was measured. The Actical recorded 26% higher activity counts (P < 0.01) in obese persons with a tilt <10 degrees, compared to normal weight persons. The ActiGraph was unaffected by BMI or tilt angle. In the second experiment, the steps recorded by the devices were compared to actual steps. Speed had the greatest influence on the accuracy these devices. At 40 m/min, the ActiGraph was the least accurate device for normal weight (38%), overweight (46%) and obese (48%) individuals. The Actical, NL-2000 and StepWatch averaged 65%, 73% and 99% of steps taken, respectively. Lastly, several generations of the ActiGraph (7164, GT1M, and GT3X), and other research grade activity monitors (Actical; ActivPAL; and Digi-Walker) were compared to a criterion measure of steps. Fifty-six participants performed treadmill walking (40, 54, 67, 80 and 94 m/min) and wore the devices for 24-hours under free-living conditions. BMI did not affect step count accuracy during treadmill walking. The StepWatch, PAL, and the AG7164 were the most accurate across all speeds; the other devices were only accurate at the faster speeds. In the free-living environment, all devices recorded about 75% of StepWatch-determined steps, except the AG7164 (99%). Based on these findings, we conclude that BMI does not affect the output of these activity monitors. However, waist-borne activity monitors are highly susceptible to under-counting steps at walking speeds below 67 m/min, or stepping rates below 100 steps/min. An activity monitor worn on the ankle is less susceptible to these speed effects and provides the greatest accuracy for step counting.

This dissertation investigated 1) the energy expenditure of stepping in place during TV commercials (commercial stepping), 2) determined the best objective tool to measure commercial stepping, 3) and assessed the efficacy of commercial stepping to increase the activity levels of sedentary, overweight adults. First, twenty-three adults (normal to obese) had their energy expenditure measured while at rest, sitting, standing, stepping in place and walking at 3.0 mph on the treadmill, followed by one hour each of sedentary TV viewing and commercial stepping in the laboratory. Stepping in place, walking at 3.0 mph, and commercial stepping, had a higher caloric requirement than either rest, or sedentary TV viewing. One hour of commercial stepping resulted in an average of 2111 actual steps. The waist mounted Digiwalker and New Lifestyles pedometers counted 72% and 80% of steps, while the ankle mounted Omron and Stepwatch counted 100% and 98% of actual steps respectively. Having established commercial stepping as a moderate intensity-measurable activity, eleven adults, participated in a 3-week pilot study to investigate the effects of commercial stepping at home (one week baseline, followed by two weeks commercial stepping across ≥90 min/day of TV watching). Compared to baseline, adults took more steps when watching TV, and watched 34% less TV during the 2nd two weeks. In the free-living environment, the StepWatch counted significantly more steps than the Omron pedometers (ankle and waist). Thirdly, this study compares two physical activity prescriptions: 1) commercial stepping across ≥90 min/day of TV watching; and 2) walking ≥30 min/day in 58 sedentary overweight adults. Outcomes were daily steps, adherence, dietary intake, TV watching and weight after 12 wks in a behavioral intervention. Both groups adhered equally to their prescriptions, and daily steps significantly (P<0.05) increased (~3000 steps/day) from 0 to 12-wks, with no difference between groups. TV viewing was significantly (P<0.05) reduced in both groups. Despite a reduction (P<0.05) in self-reported dietary intake, there were no changes in weight in either group. Instructing people to step in place during 90 minutes of TV watching results in a change in daily steps roughly equivalent to encouraging people to walk 30 min/day.

Purpose: To determine the step count accuracy of three pedometers and one accelerometer in pregnant women during treadmill walking. Methods: Subjects were 30 women in the second or third trimester (20-36 weeks) who were screened for pregnancy-related risk factors. Each subject was fitted with a belt containing three physical activity monitors: Yamax Digiwalker SW-200 (DW), New Lifestyles NL 2000 (NL), and GT3X Actigraph accelerometer (ACT). The Omron HJ-720 (HJ) was placed in the pants pocket. Subjects walked at 54, 67, 80, and 94 m•min-1 for two minutes each. Actual steps were determined by an investigator using a hand-tally counter. Percentage of actual steps was calculated for each device at each speed and compared. Results: There was a significant interaction between speed and device (F9,20=7.574,P<0.001). At all speeds, the NL and HJ were most accurate. At 54 m•min-1, the DW was significantly less accurate (P<0.001) than all other devices and the ACT was significantly less accurate (P<0.001) than the NL and HJ. At 67 m•min-1, the ACT and DW were significantly less accurate (P<0.001) than the NL and HJ. At 80 m•min-1, the DW was significantly less accurate (P=0.024) than the NL and HJ. At 94 m•min-1, the ACT was significantly less accurate (P=0.001) than the NL and HJ. No significant differences were found at any speed for the NL (P=0.996) and HJ (P=0.298). Trimester did not significantly affect device accuracy. Conclusion: In pregnant women, the ACT and DW are less accurate than the NL and HJ. The HJ appeared to be the most accurate. These results can be useful in developing further research studies and physical activity programs that focus on walking during pregnancy.

This research investigated the association of street network connectivity differences across travel modes with travel behaviour – mode choice, distance traveled and number of trips. To date research on travel behaviour relationships with urban form has not developed empirical evidence on street designs as distinct networks for walking and driving. A street network having greater connectivity and continuity for the pedestrian mode of travel vis-à-vis the vehicular network, like the Fused Grid, will likely encourage more walking. This hypothesis was investigated using a quasi-experimental approach within a rational utility behavioural framework. Local travel behaviour is theorized to be affected by desire to access goods and services (broadly termed, ‘activities’) in the community where people live. Using inferential statistics, the research tested for relationships between measured street patterns and self-reported local travel by King County, WA households. The main variables were ratios (walking : driving) of network connectivity and density, in the vicinity of travel survey households. Demographics and household characteristics, as well as other behaviourally influential urban form factors (residential density, proximity of destinations, etc.), were included in regression models, allowing control for confounding factors. Findings suggest that street networks with connectivity that provides better routing for one mode of transportation over others encourage more travel by the favored mode. The regression model demonstrated that a change from a pure small-block grid to a modified grid (i.e. Fused Grid) can result in an 11.3% increase in odds of a home-based trip being walked. The modified street pattern like a Fused Grid is also associated with a 25.9% increase, over street patterns with equivalent route directness for walking and driving, in the odds a person will meet recommended levels of physical activity. Finally, the Fused Grid’s 10% increase in relative connectivity for pedestrians is associated with a 23% decrease in local vehicle travel distance (VMT), and its improved continuity is associated with increased walking trips and distance. Conclusions: Other factors being equal, residential street networks with either more direct routing for pedestrians or more pedestrian facilities relative to vehicular network are associated with improved odds of walking and reduced odds of driving.

This thesis investigated the cost-effectiveness of a 12-month supervised aerobic walking program with or without a behavioural intervention and an educational pamphlet, compared to an unsupervised/self-directed educational pamphlet intervention, among individuals with moderate osteoarthritis (OA) of the knee. Analyses included an economic evaluation to assess the cost effectiveness of the two walking interventions from both the societal and Canadian provincial/territorial health care payer perspectives. A value of information analysis exploring the potential value of future research was also performed. Results revealed that the unsupervised/self-directed intervention was the most cost-effective approach given that it cost the least to implement and participants had higher quality-adjusted life years (QALYs). Walking, either supervised in a community setting, or unsupervised in a setting such as the home, may be a favourable non-pharmacological option for the management of OA of the knee. The thesis concludes with a policy discussion relating to the funding of non-pharmacological therapies.

The benefits of brief-duration, early exercise programs in stroke have been shown, but the effects of longer-duration aerobic training early after stroke have not been examined. The purpose of this study was to determine the effects of an early aerobic exercise program that extended beyond inpatient into outpatient rehabilitation on aerobic capacity, walking parameters (walking distance, speed, and symmetry), health-related quality of life, and balance. Patients in the subacute phase after stroke (n = 15) with mild to moderate impairment received aerobic exercise in addition to conventional rehabilitation. The study participants demonstrated significant improvement in aerobic and walking capacity, peak work rate, quality of life, balance, and gait velocity from baseline to midpoint. However, no difference was found between midpoint and final. This early aerobic exercise program following stroke significantly improved aerobic capacity, walking ability, quality of life and balance during the inpatient period although no further improvement was observed during the outpatient period.

Objective: To describe the walking characteristics of a sample of ambulatory subjects with sub-acute incomplete spinal cord injury (iSCI). Methods: 52 subjects were included in a secondary analysis of clinical and spatiotemporal measures of walking. The study sample was described as a whole and subsequently divided into subgroups on the basis of 3 clinical factors (etiology, severity, and neurological level of injury) and 4 gait factors (gait aid, velocity, symmetry, and variability). Results: Clinical and spatiotemporal parameters were highly variable across the study population. Sub–groups with unique gait features were best identified by velocity and variability. Conclusions: Spatiotemporal measures of walking provide augmented description of walking in the sub-acute iSCI population. Sub-grouping by gait factors warrants further investigation with respect to their ability to act as predictors and modifiers of treatment effect.