Noel Lythgo

Validation of the Fitbit One, Garmin Vivofit and Jawbone UP activity tracker in estimation of energy expenditure during treadmill walking and running

Abstract Objectives: To determine the validity of energy expenditure estimation made by the Fitbit One, Garmin Vivofit and Jawbone UP activity trackers during treadmill walking and running. Determining validity of such trackers will inform the interpretation of the data they generate. Design: Cross-sectional study. Method: Fourteen adults walked at 0.70, 1.25, 1.80 ms−1 and ran at 2.22, 2.78, 3.33 ms−1 on a treadmill wearing a Fitbit One, Garmin Vivofit and Jawbone UP. Estimation of energy expenditure from each tracker was compared to measurement from indirect calorimetry (criterion). Paired t-tests, correlation coefficients and Bland–Altman plots assessed agreement and proportional bias. Mean percentage difference assessed magnitude of difference between estimated and criterion energy expenditure for each speed. Results: Energy expenditure estimates from the Fitbit One and Garmin Vivofit correlated significantly (p< 0.01; r= 0.702; 0.854) with criterion across all gait speeds (0.70–3.33 ms−1). Fitbit One, Garmin Vivofit and Jawbone UP correlated significantly (p < 0.05; r = 0.729; 0.711; 0.591) with criterion across all walking speeds (0.70–1.80 ms−1). However, only the Garmin Vivofit correlated significantly (p< 0.05; r = 0.346) with energy expenditure estimations from criterion across running speeds (2.22–3.33 ms−1). Bland–Altman plots showed proportional bias for the Fitbit One and Garmin Vivofit. Energy expenditure estimations of single speeds were overestimated by the Fitbit One and underestimated by the Garmin Vivofit. Conclusions: Energy expenditure reported by the devices distinguished between walking and running, with a general increase as exercise intensity increased. However, the reported energy expenditure from these devices should be interpreted with caution, given their potential bias and error. Practical implications Although devices report the same outcome of EE estimation, they are not equivalent to each other and differ from criterion measurements during walking and running. These devices are not suitable as research measurement tools for recording precise and accurate EE estimates but may be suitable for use in interventions of behaviour change as they provide feedback to user on trends in energy expenditure. If intending to use these devices in studies where precise measurements of energy expenditure are required, researchers need to undertake specific validation and reliability studies prior to interventions and the collection of cross-sectional data.

Balance and Gait in People with Multiple Sclerosis: A Comparison with Healthy Controls and the Immediate Change after an Intervention based on the Bobath Concept.

BACKGROUND AND PURPOSE The objective of this study is to compare the balance and gait of 11 people with multiple sclerosis (MS) to 11 healthy controls and to investigate the immediate change after a single intervention based on the Bobath concept on these activities in the MS group. METHODS Balance was assessed by ground reaction forces (GRF) and centre of pressure movements during single limb standing (SLS), the Lateral Reach Test (LRT) and the Four Square Step Test (FSST). Gait was evaluated by GRF, ankle kinematics and spatiotemporal measures. RESULTS Baseline measures in the MS group showed significantly greater vertical GRF variability (p = 0.008) during SLS reached less distance on the LRT (p = 0.001) and were slower completing the FSST (p < 0.001). During gait, the MS group walked slower (p = 0.005) and had less ankle plantarflexion (PF) (p = 0.001) than the control group. Less peak vertical GRF (p < 0.001) and peak propulsive GRF (p = 0.004) at terminal stance and increased vertical GRF in midstance (p = 0.005) were observed. The measures of balance and gait were re-assessed in the MS group immediately after a 20-min intervention based on the Bobath concept delivered to the most impaired foot and ankle. After the intervention, the MS group had significant changes towards the control group values with reduced mediolateral (p = 0.002) and vertical (p = 0.016) GRF variability in the SLS task, faster FSST time (p = 0.006) and increased ankle PF during gait (p = 0.002). DISCUSSION This study provides further evidence of balance and gait limitations in people with MS and indicates that a single treatment based on principles of the Bobath concept to the foot and ankle can result in immediate improvements in balance and ankle PF during gait in people with MS. Copyright

A water-based pressure casting method for transtibial prosthetic socket fit in developing countries

Many challenges are faced by large numbers of people with lower limb amputation in developing countries. Foremost are cost and access to skilled prosthetic services. Attempts have been made to develop socket fabrication techniques that require little or no prosthetic skill. This study investigated a water pressure casting technique (PCAST) to fabricate and fit transtibial (TT) prosthetic sockets. Ethics approval and informed consent were obtained. Fifty-three adults with unilateral TT amputation were recruited from VIETCOT (Hanoi). VIETCOT staff with ISPO category II qualifications fabricated and fitted the prostheses. Firstly, a cotton sock was placed over the residual limb followed by a plaster wrap. The participant stood with the intact limb on a weight-scale and placed the residual limb into a plastic bag-type diaphragm housed in a cylindrical tank filled with water until they stood normally with half body weight supported. Upon hardening a positive plaster model was made and a socket fabricated with a distal pelite cap. A polypropylene socket was then moulded and attached to ICRC prosthetic components and a rubber foot. The same person fabricated, fitted and aligned the prosthesis. Once a participant indicated satisfaction, the following tasks were completed: timed up-and-go (TUG), six-minute walk (6MWT), walking (GAITRite mat) and satisfaction questionnaire (SATPRO). These tasks were also completed after an extended usage period (146 ± 28 days). Thirty-one of the participants were successfully fitted: fourteen fits failed, eight failed to return, withdrew or became deceased. SATPRO (n = 31) showed high levels of satisfaction (81%) on both test occasions. 6MWT increased by 28 m (p = 0.01) after the usage period. TUG, SATPRO and gait measures remained unchanged. A sub-analysis (n = 21) compared PCAST perfor-mance to original socket and prosthesis. No differences were found. In conclusion, the PCAST may assist people with TT amputation in developing countries.

Transtibial prosthetic socket shape in a developing country: a study to compare initial outcomes in pressure cast hydrostatic and patella tendon bearing designs

This study compared the physical function and comfort level of patients with unilateral transtibial amputation after being fitted with a hand-cast Patella Tendon Bearing (PTB) socket and a pressure-cast (PCAST) hydrocast socket. The latter technique aims to reduce the skill dependency currently required for socket manufacture and fit. The study was conducted at the Vietnamese Training Centre for Orthopaedic Technologies and involved seventeen Vietnamese participants with unilateral transtibial amputation, all of whom were long term users of prosthetics. All participants were fitted with two sockets manufactured using both hand-cast and PCAST techniques with International Committee of the Red Cross components. Walking tests (timed up and go test and six-minute-walk-test), spatio-temporal gait analyses and subjective comfort assessments were completed after a short acclimatisation period with each socket. The participant-preferred socket was also noted. No significant differences were found for the measures of mobility, functional capacity, spatio-temporal gait parameters, gait symmetry, perceived comfort or participant socket preference. The results show the initial patient outcomes are similar when participants are fitted with a hand-cast PTB socket and a PCAST hydrocast sockets. Future work should confirm these findings in a longer trial.

A Multiple Regression Approach to Normalization of Spatiotemporal Gait Features.

Normalization of gait data is performed to reduce the effects of intersubject variations due to physical characteristics. This study reports a multiple regression normalization approach for spatiotemporal gait data that takes into account intersubject variations in self-selected walking speed and physical properties including age, height, body mass, and sex. Spatiotemporal gait data including stride length, cadence, stance time, double support time, and stride time were obtained from healthy subjects including 782 children, 71 adults, 29 elderly subjects, and 28 elderly Parkinsons disease (PD) patients. Data were normalized using standard dimensionless equations, a detrending method, and a multiple regression approach. After normalization using dimensionless equations and the detrending method, weak to moderate correlations between walking speed, physical properties, and spatiotemporal gait features were observed (0.01 < |r| < 0.88), whereas normalization using the multiple regression method reduced these correlations to weak values (|r| <0.29). Data normalization using dimensionless equations and detrending resulted in significant differences in stride length and double support time of PD patients; however the multiple regression approach revealed significant differences in these features as well as in cadence, stance time, and stride time. The proposed multiple regression normalization may be useful in machine learning, gait classification, and clinical evaluation of pathological gait patterns.

Increased Shoe Heel Height Generates Greater Peak Knee Extension Moments than Fast Walking Speeds

Wearing high heeled footwear during gait increases risks of trips and falls, and suffering from lower-limb injuries. High heel footwear increases knee extension moment and hence knee joint load. Consequently, prolonged wearing of high heel footwear may increase risks of knee osteoarthritis. Although, many studies have investigated the effect of heel height on knee joint moments, most studies do not account for the confounding effect of walking speed. Three-dimensional gait analysis and inverse dynamics were used to investigate the effect of heel height and walking speed on the peak knee joint moment during stance. This found heel height affects the peak knee extension moment more significantly than walking speed. More importantly, this study shows that wearers of higher heel heights are likely to be exposed to greater knee compression forces than when walking faster.

Validity of the Four Square Step Test to Assess Dynamic Balance, Step Velocity and Displacement

The four square step test (FSST) is commonly used to assess dynamic standing balance in elderly adult populations. To date, only the time (recorded by a stop-watch) to complete the test has been used. Other important dynamic balance information such as step velocity and step displacement can be extracted. This study re-examined the validity of recording the FSST time with a stop-watch by comparing it to a “gold standard” method (Vicon) and investigated the relationship between FSST stop-watch time and measures of step velocity, step displacement, and age. After familiarization, fourty-one healthy adults (42 ± 12 yrs.) completed three FSST trials. The FSST time was recorded by a stop-watch and the participants’ foot movements were simultaneously recorded by a Vicon motion system (120 Hz). Measures extracted from the Vicon system were FSST time, step velocity (four directions) and step displacement (four directions). A paired t-test was used to compare FSST time recorded by each system. Pearson’s correlation analyses were conducted to identify relationships between measures. No significant difference was found between the FSST time recorded by the methods (mean difference = 0.02 ± 0.11 s). Moreover, a strong positive linear relationship (r = 0.99, p < 0.0001) was found between the FSST time recorded by the methods. A moderate linear relationship was found between the FSST time (Vicon) and step velocity (r = 0.67, p < 0.0001). Poor linear relationships were found between (1) step velocity and step displacement, (2) FSST time (Vicon) and step displacement, (3) FSST time (both methods) and age, (4) age and step velocity, and (5) age and step displacement. In conclusion, the FSST stop-watch method is valid. Moreover, it may be used to predict step velocity but not step displacement. No relationship was found between age and the FSST time, step velocity or step displacement.