Study design
This pilot study consisted of a six-month intervention. Subjects participated in a home-based exercise programme, with exercise instructions through videos on a tablet PC and daily physical activity registration through a necklace-worn sensor. During the supervised first 3 months, participants were contacted by phone for weekly coaching and help with the technology as needed. During the unsupervised last 3 months participants were not contacted by phone but could call their coach if they encountered problems. When issues couldn’t be solved by phone, the coach visited the participant at home. Both coaches involved in the exercise programme had a background in human movement sciences and/or physiotherapy, and were trained in motivational techniques for physical activity stimulation in older adults. Each participant was assigned to a coach. The study protocol was approved by the Medical Ethical Committee of University Medical Center Groningen (METc no. 2013/246). A full, detailed description of the study design is provided elsewhere [24].
Subjects
Community-dwelling pre-frail older adults living in the northern Netherlands were recruited and informed consent was obtained. Inclusion criteria were being over age 70 and the ability to walk at least 10 m independently or using a walking aid. Subjects had to be pre-frail, as indicated by the Groningen Frailty Indicator (GFI) (score of 4 or 5 out of a range of 0–15), which denotes a minor elevated chance of loss of functionality and heightened disability [3, 25]. Subjects needed sufficient mental capacity to perform a tablet-assisted exercise programme independently at home, as indicated by the score on the GFI and an additional subjective check by the coach. Exclusion criteria were physical conditions that hamper safe independent execution of a home-based exercise programme or working with a tablet, such as Parkinson’s disease stage 4 or 5 or severe visual problems. Candidates were recruited between January and November 2014 by means of advertisements and leaflets for participants of the integrated care programme Embrace [26].
Exercise programme
The exercise regimen consisted of lower-body strength and balance exercises based on the Otago Kitchen Table Exercise programme [27, 28]. Exercise included stepping out sideways, lifting the legs alternatingly to the buttock, rising on toes and heels, and lifting legs while seated. Exercise progressed in 18 levels, increasing the exercise burden by adding more repetitions and longer training time as well as incorporating the use of ankle weights in the higher levels. Level 1 consisted of a 10-min training and the exercise burden increased to 40 min/day in level 18. The exercise programme is shown in detail in an additional table in PDF format [see Additional file 1: “Additional file 1 Table exercise program contents.pdf]. Each level was presented with an instructional video on the tablet. All participants started at level 1 and could progress through the levels as desired. Participants exercised five times a week. Adherence to the program was calculated based on completion of exercise bouts. In addition to the strength and balance exercises, participants were encouraged to increase their daily overall physical activity by a visual graph showing their daily physical activity progression. The encouragement strategies employed were based upon the transtheoretical model of behaviour change (Stages of Change model) and social-cognitive theory. Both the exercise programme and the motivational strategies are explained in detail elsewhere [24].
Technical applications
Sensor
The necklace-worn sensor package included a miniature hybrid sensor containing a 3D-MEMS accelerometer and a barometric pressure sensor. Accelerometry data were sampled at 50 Hz with a range of 8 g, barometric data were sampled at 25 Hz. A micro-SD card was used for storage and exchange of data. The sensor weighed about 30 g and measured 55x25x10mm (Research prototype, Philips Research, Eindhoven, The Netherlands). Participants were asked to connect the sensor to the tablet manually using a USB cable to transfer data and load the battery every night. The sensor was used to measure daily physical activity and the performance on the functional tests.
Tablet PC
Participants received exercise instructions and distant feedback through a tablet PC, a Dell Latitude 10 with Windows 8 operating system. The tablet PC was adjusted to independent older adult use, keeping menus and necessary interaction as simple as possible. Exercise instructions were given using a web-based application (providing exercise videos and performance monitoring features; Fig. 1) that a participant could imitate. Participants could choose their own level of exercising in consultation with the coach. Each level had a different video showing the full exercise bout. The exercise programme was provided by an internet-based application running on a remote web server. Internet connection was provided by a 3G or 4G mobile internet card inserted into the tablet or by the participant’s own home Wi-Fi.
Evaluation methods
Cohort characteristics
The following variables were collected at baseline: gender, age, body mass index, GFI score, Falls Efficacy Scale International (FES-I) score, computer experience, smartphone ownership and internet type.
Functional performance
Functional performance was assessed by means of three tests performed at a maximum but safe pace before the start of the intervention (baseline), after finishing the supervised first 3 months (post-test) and after finishing the unsupervised last 3 months (follow-up) at the participants’ homes. The tests were demonstrated and assisted by the researcher and the coach. First participants were asked to perform three separate sit-to-stand (STS) actions without using chair armrests [14, 18]. Based on the performance of the STS it was evaluated whether it was safe to ask the participant to continue the assessment with the two more difficult performance tests, Next, the Timed Up & Go test (TUG) was performed twice [29, 30]. The Five times Chair-Rise test (CR) was performed twice provided the participant could perform this task [17]. The tests were assessed based on data from the necklace-worn sensor as well as a stopwatch to measure time in seconds needed to perform the test [19]. The average time needed for repetitions of the functional performance tests per measurement point was calculated and used for comparison between the three measurement points. A drop in score means an improvement in functional performance. An extensive description of the measurement procedures has been published previously [24].
Daily physical activity
Daily physical activity was assessed by means of the self-reported Short QUestionnaire to ASses Health-enhancing physical activity (SQUASH) [31], which addresses questions about habitual physical activity level during a week and the necklace-worn sensor, which was worn daily throughout the entire intervention. As the sensor was a research prototype; the SQUASH was chosen to explain the research question regarding daily physical activity.
Sensor-wearing compliance was assessed by unplugging the sensor from the tablet – the sensor only recorded data when it was unplugged. These recorded data were uploaded into the system and automatically analysed at the next plug-in for sensor recharging. The coach could look into these data in the system daily, and when there were several consequent days of errant behaviour (flatline; only a small number of hours of data collected instead of at least 4 h; data that could not be translated by the sensor due to unclear patterns) the coach got in contact with the participant to check sensor-wearing adherence, progress and technology performance. Participants wore the sensor during the week before starting the exercise programme for baseline assessment. The week before the end of the supervised period was regarded as the post-test measurement, and the week before the end of the unsupervised period was regarded as the follow-up measurement of daily physical activity. Daily physical activity was expressed by means of Time-on-legs (TOL), defined as the percentage of time during the day spent active on one’s legs (standing, walking, shuffling and analogous activities) [19, 20]. The assessment weeks at the three measurement points provided seven measurement days each. Average physical activity over these 7 days was then calculated for all three measurement points. If one or more of the seven adjacent measurement days were not available, the physical activity measurement of an adjacent day prior to or after the seven-day measurement period was added to complete a seven-day measurement period. Physical activity as measured by the necklace-worn sensor was compared between the three measurement points.
Statistical analysis
Means and standard deviations were calculated for all variables at baseline, post-test and follow-up. To test whether baseline, post-test and follow-up were equal, we performed an analysis of variance (ANOVA) with repeated measurements. Comparisons between the average scores at baseline, post-test and follow-up on the three functional performance tests (according to the stopwatch time) and daily physical activity (both sensor- and self-reported outcomes) were performed using a paired sample t-test for normally distributed variables. As the scores on the functional performance tests were skewed, a gamma distribution was used. Bonferroni adjustments for multiple comparisons were performed to assess the periods responsible for significant outcomes. Cohen’s d was calculated for baseline versus post-test measures, post-test versus follow-up measures and baseline versus follow-up measures using the following formula: Cohen’s d = (M1 – M2) / SDpooled, where M is the mean and SD the standard deviation. To interpret the effect of Cohen’s d, the following benchmarks were used: 0.01–0.20 for a very small effect, 0.20–0.50 for a small effect, 0.50–0.80 for a medium effect and > 0.80 for a large effect [32, 33]. The maximum number of available data at each time point was used. No data imputation was applied for missing data. Because of the small data set, winsorizing was applied for outliers after data inspection. SPSS statistical software (version 24.0, IBM SPSS, Chicago) was used.