Description

Background Parkinson's disease is a progressive neurodegenerative disorder and one of the leading causes of disability worldwide. Impaired walking is considered one of the most bothersome symptoms that people with Parkinson's disease wish to improve, affecting independence, ability to work, and quality of life. Walking impairment is present from the early stage of the disease with an expected progression and a more frequent presentation along the course of the disease. Currently, only few medical treatments exist that target walking, and these show minor effects while causing side effects. Non-pharmacological interventions that can improve or prevent loss of walking ability are therefore highly warranted.

Exercise is a promising non-pharmacological intervention in people with Parkinson's disease with studies reporting improved walking performance following different exercise modalities, including high-intensity aerobic exercise. Despite extensive research investigating the effects of various exercise interventions on walking, few have examined more traditional walking training. This is somewhat surprising as walking is task-specific training for walking itself, while also being feasible and showing promising results in people with Parkinson's disease. In addition, walking is easily accessible and a potential efficient low-cost intervention that is commonly used and therefore well-known in clinical rehabilitation practice. Yet only two long-term studies could be located applying walking training. Despite being long-term, these studies are limited by 1) not considering possible factors facilitating adherence, 2) not performing follow-up testing, 3) not applying any inclusion criterion for walking impairment implying that any potential effects might be diminished due to well-functioning participants without walking impairments, 4) not including a comprehensive test battery (i.e., no registration of comorbidities, physical activity level, health-related quality of life), and 5) not investigating the effect on perceived walking difficulties despite the relevance of understanding the subjective impact of walking training. Further evaluation of walking interventions is therefore needed in people with Parkinson's disease.

Despite the importance of a physically active lifestyle, only 27% (potentially less) of people with Parkinson's disease meet the established physical activity recommendations (≥ 150 min/week of moderate to vigorous physical activity). Therefore, it is very challenging to design a walking intervention that increases physical activity levels while being sustainable. To do so, it is essential to incorporate motivational factors that facilitate adherence. These include high self-efficacy, low cost, less travel, self-perceived positive effects of walking, and support from family/carers and health professionals. To comply with these factors, remotely or partly supervised home-based exercise has been suggested as a feasible and effective strategy to alleviate Parkinson's disease motor symptoms. Another aspect to consider is group vs. individually based exercise sessions. Both have shown equally effective in improving functional capacity in healthy individuals, but combined group- and individual-based exercise has been recommended as the most attractive model for the broadest range of people with Parkinson's disease. Overall, by incorporating these strategies in walking training, this exercise modality might offer a sustainable, cost-effective, and easy-to-apply intervention that can be offered in local communities worldwide. This would also include people with Parkinson's disease living without easy access to training facilities or who are governed by poor healthcare systems. Another even more easy-to-apply and low-cost intervention to increase physical activity, is to offer a wearable activity tracker. One study reported increased physical activity level in people with Multiple sclerosis when offering a wearable activity tracker and engaging in group- and individual motivational online meetings compared to a control group. However, to the investigator's knowledge, this has not been assessed in people with Parkinson's disease.

Therefore, the primary aim is to investigate the efficacy of a 24-week combined supervised group- and non-supervised individual-based walking intervention (WALK) compared to both a group receiving a wearable activity tracker (HOME) and a control group (CON) on perceived walking difficulties in people with Parkinson's disease. The secondary aims are to identify and characterize responders and non-responders to walking training and to investigate the cost-effectiveness of these exercise interventions.

The hypothesis is that the WALK group will be superior to HOME and CON, while HOME will be superior to CON after 24 weeks in reducing perceived walking difficulties, which will be sustained after a 24-week follow up.

Methods and materials The project includes one main study and two embedded studies. Study 1 (main study): A single-blinded randomized controlled trial including three interventions (WALK, HOME and CON). Tests will be conducted at 0, 24 and 48 weeks.

Study 2: Identification and characterization of responders (i.e., ≥3 point decrease in the generic walking scale or ≥6% increase in maximal oxygen consumption) and non-responders to walking training.

Study 3: Economic evaluation of WALK compared to HOME and CON.

Statistical considerations The study sample size is powered based on descriptive Parkinson's disease data on the primary outcome (i.e., generic walking scale) and the assumption that a clinically meaningful change of ≥3 points will be detected between all three groups after 24 weeks (i.e. WALK > HOME > CON). Moreover, based on the inclusion criteria, a more homogeneous population sample compared to the previous study is expected, and thus a lower standard deviation. Lastly, it is expected that 15% will drop out. A one-way ANOVA was used to estimate the sample size (a=0.05, power=0.8, 24-weeks post mean values for CON, HOME and WALK = 15, 12, 9 ± 8, and dropout proportion = 15%). The calculation showed that 43 people with Parkinson's disease should be enrolled into each group.