Physiological and biomechanical responses to walking underwater on a non-motorised treadmill: Effects of different exercise intensities and depths in middle-aged healthy women

Non-motorised underwater treadmills are commonly used in fitness activities. However, no studies have examined physiological and biomechanical responses of walking on non-motorised treadmills at different intensities and depths. Fifteen middle-aged healthy women underwent two underwater walking tests at two different depths, immersed either up to the xiphoid process (deep water) or the iliac crest (shallow water), at 100, 110, 120, 130 step-per-minute (spm). Oxygen consumption (VO2), heart rate (HR), blood lactate concentration, perceived exertion and step length were determined. Compared to deep water, walking in shallow water exhibited, at all intensities, significantly higher VO2 (+13.5%, on average) and HR (+8.1%, on average) responses. Water depth did not influence lactate concentration, whereas perceived exertion was higher in shallow compared to deep water, solely at 120 (+40%) and 130 (+39.4%) spm. Average step length was reduced as the intensity increased (from 100 to 130 spm), irrespective of water depth. Expressed as a percentage of maximum, average VO2 and HR were: 64–76% of peak VO2 and 71–90% of maximum HR, respectively at both water depths. Accordingly, this form of exercise can be included in the “vigorous” range of exercise intensity, at any of the step frequencies used in this study.

Pedestrian self-reported exposure to distraction by smart phones while walking and crossing the road

Pedestrian crashes account for approximately 14% of road fatalities in Australia. Crossing the road, while a minor part of total walking, presents the highest crash risk because of potential interaction with motor vehicles. Crash risk is elevated by pedestrian illegal use of the road, which may be widespread (e.g. 20% of crossings at signalised intersections at a sample of sites, Brisbane) and enforcement is rare. Effective road crossing requires integration of multiple skills and judgements, any of which can be hindered by distraction. Observational studies suggest that pedestrians are increasingly likely to ‘multitask’, using mobile technology for entertainment and communication, elevating the risk of distraction while crossing. To investigate this, intercept interviews were conducted with a convenience sample of 211 pedestrians aged 18-65 years in Brisbane CBD. Self-reported frequency of using a smart phone for activities at two levels of distraction: cognitive only (voice calls); or cognitive and visual (text messages, internet access) while walking or crossing the road was collected. Results indicated that smart phone use for potentially distracting activities while walking and while crossing the road was high, especially among 18-30 year olds, who were significantly more likely than 31-44yo or 45-65yo to report smart phone use while crossing the road. For 18-30yo and the higher risk activity of crossing the road, 32% texted at high frequency levels and 27% used internet at high frequency levels. Risky levels of distracted crossing appear to be a growing safety issue for 18-30yo, with greater attention to appropriate interventions needed.

Mechanical analysis of foot plantar fascia during normal walking condition

Foot plantar fascia is an important foot tissue in stabilizing the longitudinal arch of human foot. Direct measurement to monitor the mechanical situation of plantar fascia at human locomotion is difficult. The purpose of this study was to construct a three-dimensional finite element model of the foot to calculate the internal stress/strain value of plantar fascia during different stage of gait. The simulated stress distribution of plantar fascia was the lowest at heel-strike, which concentrated on the medial side of calcaneal tubercle. The peak stress of plantar fascia was appeared at push-off, and the value is more than 5 times of the heel-strike position. Current FE model was able to explore the plantar fascia tension trend at the main sub-phases of foot. More detailed fascia model and intrinsic muscle forces could be developed in the further study.

Image-based midsole insert design and the material effects on heel plantar pressure distribution during simulated walking loads

The primary objective of this paper is to study the use of medical image-based finite element (FE) modelling in subjectspecific midsole design and optimisation for heel pressure reduction using a midsole plug under the calcaneus area (UCA). Plugs with different relative dimensions to the size of the calcaneus of the subject have been incorporated in the heel region of the midsole. The FE foot model was validated by comparing the numerically predicted plantar pressure with biomechanical tests conducted on the same subject. For each UCA midsole plug design, the effect of material properties and plug thicknesses on the plantar pressure distribution and peak pressure level during the heel strike phase of normal walking was systematically studied. The results showed that the UCA midsole insert could effectively modify the pressure distribution, and its effect is directly associated with the ratio of the plug dimension to the size of the calcaneus bone of the subject. A medium hardness plug with a size of 95% of the calcaneus has achieved the best performance for relieving the peak pressure in comparison with the pressure level for a solid midsole without a plug, whereas a smaller plug with a size of 65% of the calcaneus insert with a very soft material showed minimum beneficial effect for the pressure relief.

The effect of an in–shoe orthotic heel lift on loading of the Achilles tendon during shod walking

- Study Design Controlled laboratory study - Objective To investigate the effect of a 12–mm in–shoe orthotic heel lift on Achilles tendon loading during shod walking using transmission–mode ultrasonography. - Background Orthotic heel lifts are thought to lower tension in the Achilles tendon but evidence for this effect is equivocal. - Methods The propagation speed of ultrasound, which is governed by the elastic modulus and density of tendon and is proportional to the tensile load to which it is exposed, was measured in the right Achilles tendon of twelve recreationally–active males during shod treadmill walking at matched speeds (3.4±0.7 km/h), with and without addition of a heel lift. Vertical ground reaction force and spatiotemporal gait parameters were simultaneously recorded. Data were acquired at 100Hz during 10s of steady–state walking. Statistical comparisons were made using paired t–tests (α=.05). - Results Ultrasound transmission speed in the Achilles tendon was characterized by two maxima (P1, P2) and minima (M1, M2) during walking. Addition of a heel lift to footwear resulted in a 2% increase and 2% decrease in the first vertical ground reaction force peak and the local minimum, respectively (P<.05). Peak ultrasonic velocity in the Achilles tendon (P1, P2, M2) was significantly lower with addition of an orthotic heel lift (P<.05). - Conclusions Peak ultrasound transmission speed in the Achilles tendon was lower with the addition of a 12–mm orthotic heel lift, indicating the heel lift reduced tensile load in the Achilles tendon, thereby counteracting the effect of footwear. These findings support the addition of orthotic heel lifts to footwear in the rehabilitation of Achilles tendon disorders where management aims to lower tension within the tendon. - Level of Evidence Therapy, level 2a

Achilles tendon loading patterns during barefoot walking and slow running on a treadmill: An ultrasonic propagation study

Measurement of tendon loading patterns during gait is important for understanding the pathogenesis of tendon "overuse" injury. Given that the speed of propagation of ultrasound in tendon is proportional to the applied load, this study used a noninvasive ultrasonic transmission technique to measure axial ultrasonic velocity in the right Achilles tendon of 27 healthy adults (11 females and 16 males; age, 26 ± 9 years; height, 1.73 ± 0.07 m; weight, 70.6 ± 21.2 kg), walking at self-selected speed (1.1 ± 0.1 m/s), and running at fixed slow speed (2 m/s) on a treadmill. Synchronous measures of ankle kinematics, spatiotemporal gait parameters, and vertical ground reaction forces were simultaneously measured. Slow running was associated with significantly higher cadence, shorter step length, but greater range of ankle movement, higher magnitude and rate of vertical ground reaction force, and higher ultrasonic velocity in the tendon than walking (P < 0.05). Ultrasonic velocity in the Achilles tendon was highly reproducible during walking and slow running (mean within-subject coefficient of variation < 2%). Ultrasonic maxima (P1, P2) and minima (M1, M2) were significantly higher and occurred earlier in the gait cycle (P1, M1, and M2) during running than walking (P < 0.05). Slow running was associated with higher and earlier peaks in loading of the Achilles tendon than walking.

Variation in the walking time to bus stop by the degree of transit captivity

Measures of transit accessibility are important in evaluating transit services, planning for future services and investment on land use development. Existing tools measure transit accessibility using averaged walking distance or walking time to public transit. Although the mode captivity may have significant implications on one’s willingness to walk to use public transit, this has not been addressed in the literature to date. Failed to distinguish transit captive users may lead to overestimated ridership and spatial coverage of transit services. The aim of this research is to integrate the concept of transit captivity into the analysis of walking access to public transit. The conventional way of defining “captive” and “choice” transit users showed no significant difference in their walking times according to a preliminary analysis. A cluster analysis technique is used to further divide “choice” users by three main factors, namely age group, labour force status and personal income. After eliminating “true captive” users, defined as those without driver’s licence or without a car in respective household, “non-true captive” users were classified into a total of eight groups having similar socio-economic characteristics. The analysis revealed significant differences in the walking times and patterns by their level of captivity to public transit. This paper challenges the rule-of-thumb of 400m walking distance to bus stops. In average, people’s willingness to walk dropped drastically at 268m and continued to drop constantly until it reached the mark of 670m, where there was another drastic drop of 17%, which left with only 10% of the total bus riders willing to walk 670m or more. This research found that mothers working part time were the ones with lowest transit captivity and thus most sensitive to the walking time, followed by high-income earners and the elderly. The level of captivity increases when public transit users earned lesser income, such as students and students working part time.

Does gait speed indicate prosthetic walking potential following lower limb amputation?

Background: Gait speed is an indicator of walking ability, morbidity and mortality; and is a reliable, valid and sensitive outcome measure commonly used in the rehabilitation setting. Gait speed is a quick and efficient assessment method; yet, to date, there has been little investigation of its potential use in populations with lower limb amputation.

Long time, no see? (DIY walking)

Building on the launch of an early prototype at Balance Unbalance 2013, we now offer a fully realised experience of the ‘Long Time, No See?’ site specific walking/visualisation project for conference users to engage with on a do it yourself basis, either before, during or after the event. ‘Long Time, No See?’ is a new form of participatory, environmental futures project, designed for individuals and groups. It uses a smartphone APP to guide processes of individual or group walking at any chosen location—encouraging walkers to think in radical new ways about how to best prepare for ‘stormy’ environmental futures ahead. As part of their personal journeys participants’ contribute site-specific micro narratives in the form of texts, images and sounds, captured via the APP during the loosely ‘guided’ walk. These responses are then uploaded and synthesised into an ever-building audiovisual and generative artwork/‘map’ of future-thinking affinities, viewable both online at long-time-no-see.org (in Chrome) (and at the same time on a large screen visualisations at QUT’s Cube Centre in Brisbane Australia). The artwork therefore spans both participants’ mobile devices and laptops. If desired outcomes can also be presented publicly in large screen format at the conference. ‘Long Time, No See?’ has been developed over the past two years by a team of leading Australian artists, designers, urban/environmental planners and programmers.