Slow-SPEED UK is an 18-month randomised, double-blind feasibility trial evaluating the delivery, adherence, and acceptability of a digitally supported physical activity programme in community-dwelling adults aged 40 and over with objectively confirmed hyposmia (reduced sense of smell) and low baseline physical activity. Participants are randomly assigned 1:1 to either a full-dose activity-support programme (targeting a 100% increase in daily step count) or a very low-dose active control (targeting a 10% increase). Both arms are delivered via a smartphone application linked to a wearable activity monitor (Fitbit Charge 6), with personalised weekly goals expressed as relative percentages to maintain blinding. The study is not designed to test clinical efficacy.
Slow-SPEED UK is an 18-month, randomised, double-blind, parallel-group feasibility trial evaluating the feasibility, acceptability, and safety of a digitally supported physical activity programme in community-dwelling adults aged 40 and over with objectively confirmed hyposmia (reduced sense of smell) and low baseline physical activity. The study is not designed or powered to assess clinical efficacy or disease outcomes. Participants are identified through two routes: the PREDICT-PD research platform at Queen Mary University of London, and the Smell and Taste Clinic at James Paget University Hospital NHS Foundation Trust. Potential participants undergo telephone pre-screening followed by confirmatory olfactory testing using the 40-item University of Pennsylvania Smell Identification Test (UPSIT). Those scoring at or below the 15th percentile for age and sex are classified as hyposmic. Eligible individuals then enter a 4-week run-in period during which habitual daily step count is measured using a Fitbit Charge 6. Only those averaging fewer than 7,000 steps per day over at least 21 valid days proceed to randomisation. If recruitment falls below 70% of target after the first two months, and subject to Sponsor approval and REC amendment, the eligibility threshold may be broadened to fewer than 10,000 steps per day. Eligible participants are randomly assigned 1:1 to one of two arms using sequentially numbered opaque sealed envelopes, stratified by age, sex, baseline activity level, and severity of smell loss. Double-blinding is maintained by presenting all activity goals within the smartphone application as relative percentage targets rather than absolute step values, ensuring neither participants nor investigators are aware of group allocation during the study period. Both arms use the Slow-SPEED smartphone application integrated with the Fitbit Charge 6 wearable activity tracker. The intervention arm targets a progressive increase in daily step count up to 100% above individual baseline, with weekly goals increasing by 5% increments. The active control arm targets a 10% increase above baseline, with weekly goals increasing by 0.5% increments. Both arms use the same application structure, automated feedback, goal progression algorithm, and motivational features, including gamification, visualised progress, and optional non-directive motivational prompts. All participants also complete assessments using the Roche Mobile Application V2 (remote motor tasks performed every 6 weeks throughout the study period) and wear an Axivity AX6 accelerometer for 7-day bursts at baseline, 9 months, and 18 months. Assessments are conducted at three time points: baseline (in-person), 9 months (remote), and 18 months (in-person). Baseline and 18-month in-person visits include olfactory testing (UPSIT), blood pressure measurement using standard sphygmomanometry, clinical motor assessment (MDS-UPDRS Part III), digital motor tasks (BRAIN test, Digital Finger Tapping, Manus Neurodynamica digital pen, NeuroClues eye-tracking), and a structured battery of questionnaires covering physical activity (LAPAQ), mood and anxiety (HADS), sleep quality (PSQI), quality of life, autonomic symptoms (SCOPA-AUT), and cognitive screening (MoCA). The 9-month remote assessment includes questionnaires and remote digital task completion. Physical activity is measured continuously throughout the study period via the Fitbit Charge 6. The primary endpoint is the change in average daily step count from baseline (weeks 0-4) to the final four weeks of the 18-month study period, analysed descriptively as a measure of engagement and sustainability. Secondary endpoints include change in moderate-to-vigorous physical activity (MVPA), wearable-derived digital mobility and gait measures, motor and non-motor assessments, and participant-reported outcomes including health-related quality of life and usability of the digital tools. The primary objective is to evaluate feasibility, defined by recruitment rate, retention, adherence to the intervention, engagement with digital tools, completeness of outcome data, and safety over 18 months. Secondary objectives are descriptive and exploratory. All analyses follow the intention-to-treat principle and emphasise estimation with 95% confidence intervals rather than hypothesis testing. Results will be used to inform the design and operational parameters of a future definitive trial.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
QUADRUPLE
Enrollment
110
Gamified motivational smartphone app
Change in Average Daily Step Count
Change in average daily step count from baseline (weeks 0-4) to the final four weeks of the 18-month study period (approximately weeks 75-78), measured continuously using the Fitbit Charge 6 wearable activity monitor. Average daily step count will be calculated across four-week periods and analysed descriptively as a measure of engagement and sustainability in keeping with the feasibility aims of the study.
Time frame: Baseline (weeks 0-4) to 18 months (weeks 75-78)
Feasibility of Study Delivery
Composite feasibility outcome assessed by: (1) proportion of eligible participants who consent to take part (recruitment rate); (2) proportion of randomised participants who complete the 18-month study period (retention); (3) adherence to the intervention, measured by app engagement metrics and Fitbit wear time; (4) completeness of remote and in-person assessment data; and (5) frequency and nature of adverse events (safety).
Time frame: Throughout the 18-month study period, with summaries at 9 months and 18 months
Change in Moderate-to-Vigorous Physical Activity (MVPA) Intensity
Change in mean daily minutes spent at or above 64% of age-predicted maximum heart rate (HRmax), measured continuously via the Fitbit Charge 6 photoplethysmography sensor. Distribution of time across intensity bands will be described and the feasibility of capturing sustained heart-rate data over 18 months will be assessed. Analyses are exploratory only.
Time frame: Baseline (weeks 0-4) to 9 months and 18 months
Cardiorespiratory Fitness: Estimated VO₂max
Feasibility of obtaining a remote estimate of aerobic fitness (VO₂max) via the Fitbit algorithm throughout the study period. Analyses will focus on completion rates, participant tolerance, and signal stability of remote VO₂max estimation. Resting heart rate and heart rate variability (HRV) will also be summarised as the average daily resting values to assess feasibility and stability of remote cardiovascular monitoring.
Time frame: Continuously throughout the 18-month study period, with summaries at baseline, 9 months, and 18 months
Blood Pressure
Feasibility of repeated blood pressure measurement using standard sphygmomanometry, assessed at baseline and 18-month in-person visits. Supine and standing readings will be taken in accordance with American Autonomic Society recommendations to assess orthostatic hypotension. Collected for safety monitoring and feasibility assessment only; not used for clinical diagnosis.
Time frame: Baseline and 18 months (in-person visits)
Remote Digital Motor Assessment: Roche Mobile Application V2
Feasibility of repeated remote motor task completion using the Roche Mobile Application V2 smartphone platform. Active tasks include finger tapping, shape drawing, reaction time, information processing, executive functioning, balance, gait, and upper limb performance, administered every 6 weeks throughout the study period. Feasibility assessed by number of data points received, proportion of expected submissions completed, and drop-off patterns across predefined 6-week windows from 0 to 78 weeks.
Time frame: Every 6 weeks from randomisation to 18 months (approximately 13 assessment windows)
Structured Motor Examination: MDS-UPDRS Part III, Functional Gait Assessment, and Mini-BESTest
Feasibility of administering in-person structured motor assessments including the Movement Disorder Society Unified Parkinson's Disease Rating Scale Part III (MDS-UPDRS Part III), the Functional Gait Assessment (FGA), and the Mini-Balance Evaluation Systems Test (Mini-BESTest), with and without cognitive dual-tasking. Examinations will be video recorded with participant consent to allow baseline and follow-up comparison. Videos are not used for clinical decision-making.
Time frame: Baseline and 18 months (in-person visits)
Upper Limb Digital Motor Performance: BRAIN Test, Digital Finger Tapping, and Manus Neurodynamica Digital Pen
Feasibility of administering digital upper limb motor assessments at in-person visits, including: (1) the Bradykinesia Akinesia Incoordination (BRAIN) test, a validated computer-based keyboard tapping task; (2) the Digital Finger Tapping test; and (3) the Manus Neurodynamica digital pen, an AI-based handwriting and fine-motor assessment device recording kinematic and dynamic features of writing and drawing. These tools are included as exploratory assessments of upper limb motor function.
Time frame: Baseline and 18 months (in-person visits)
Free-Living Mobility and Gait: Axivity AX6 Accelerometer
Feasibility of collecting continuous raw accelerometer data from a 6-axis inertial movement sensor (Axivity AX6) worn on the dominant wrist for 7-day bursts at specified time points. Data will provide wearable-derived digital mobility and gait metrics in free-living conditions. Analyses will assess completion rates, wear-time compliance, and data quality across assessment windows.
Time frame: Baseline, 9 months, and 18 months (7-day wear bursts)
Oculomotor Assessment: NeuroClues Eye-Tracking
Feasibility of administering a standardised high-frequency binocular eye-tracking battery (NeuroClues) at in-person visits, including prosaccades, antisaccades, fixation, and pursuit tasks. Key endpoints include prosaccade latency (ms), antisaccade latency (ms), antisaccade error rate (%), fixation stability, and saccadic intrusions. Included as an exploratory assessment of oculomotor control only.
Time frame: Baseline and 18 months (in-person visits)
Sleep Quality: Fitbit Sleep Metrics and Pittsburgh Sleep Quality Index (PSQI)
Feasibility of remote long-term sleep monitoring using the Fitbit Charge 6, capturing sleep onset latency (SOL), total sleep time (TST), sleep efficiency (SE), and duration of sleep stages (deep, light, REM, and awake). Complemented by the validated Pittsburgh Sleep Quality Index (PSQI) questionnaire administered at each assessment time point. Feasibility assessed by data completeness, wear-time adherence, and questionnaire completion rates.
Time frame: Fitbit continuously throughout 18 months; PSQI at baseline, 9 months, and 18 months
Mood, Anxiety, and Psychological Wellbeing: HADS and Oxford Happiness Questionnaire
Feasibility of repeated administration of the Hospital Anxiety and Depression Scale (HADS) and the Oxford Happiness Questionnaire (OHQ), a 29-item self-report measure of subjective wellbeing. Feasibility assessed by questionnaire completion rates and missing data patterns. Mood and autonomic symptoms are also captured via MDS-UPDRS Part I at in-person visits.
Time frame: Baseline, 9 months, and 18 months
Cognitive Function: Montreal Cognitive Assessment (MoCA)
Feasibility of administering the Montreal Cognitive Assessment (MoCA) at in-person visits to ensure participants can engage appropriately with study procedures and to assess the feasibility of repeated in-person cognitive testing in this population. Not used for clinical diagnosis or prediction.
Time frame: Baseline (in-person visit)
Autonomic Symptoms: SCOPA-AUT
Feasibility of repeated administration of the validated Scales for Outcomes in Parkinson's Disease-Autonomic (SCOPA-AUT) questionnaire as a general autonomic function measure. Feasibility assessed by completion rates across repeated remote and in-person administrations.
Time frame: Baseline, 9 months, and 18 months
Olfactory Function: UPSIT
Feasibility of repeated olfactory assessment using the 40-item University of Pennsylvania Smell Identification Test (UPSIT) at in-person visits. UPSIT scores will be recorded to assess the feasibility and stability of repeated olfactory testing across the study period. Results are not used for individual risk prediction or clinical diagnosis.
Time frame: Baseline and 18 months (in-person visits)
Health-Related Quality of Life and Functional Status: WHOQOL-BREF and Lawton iADL Scale
Feasibility of administering the World Health Organisation Quality of Life assessment (WHOQOL-BREF) and Lawton's Instrumental Activities of Daily Living (iADL) scale at annual assessment time points. Feasibility assessed by completion rates, missing data patterns, and participant burden ratings.
Time frame: Baseline and 18 months
Smartphone Application Usability: System Usability Scale (SUS)
Feasibility and acceptability of the Slow-SPEED smartphone application assessed using the System Usability Scale (SUS). Participant ratings will be used to evaluate usability and inform improvements to the user experience for a future definitive trial.
Time frame: 9 months and 18 months
Digital Engagement and App Usage
Quantitative assessment of participant interaction with the Slow-SPEED application, measured by total number of app opens across predefined time windows: baseline period (0-1 month), and post-randomisation periods of 1-6 months, 6-12 months, and 12-18 months. Reported separately by study arm.
Time frame: Throughout the 18-month study period
Adherence to Weekly Step and Activity Goals
Compliance with the intervention assessed by: (1) proportion of participants achieving an increase in mean daily step count relative to baseline at 18 months, categorised as 0-25%, 26-50%, 51-75%, and 76-100% increase; (2) proportion achieving an increase in mean daily MVPA minutes relative to baseline, using the same categories; (3) total number of weekly step goals completed across the 18-month period; and (4) total number of weekly intensity goals completed across the 18-month period. Reported separately for both study arms.
Time frame: Throughout the 18-month study period, with summaries at 6, 12, and 18 months
Participant Retention
Proportion of randomised participants remaining in the study without withdrawal, assessed at 6, 12, and 18 months following randomisation. Reported separately for the intervention and active control arms.
Time frame: 6 months, 12 months, and 18 months
Motivators and Barriers to Physical Activity Engagement
Feasibility of administering a self-designed questionnaire to explore participant-reported motivators and barriers to engagement with the physical activity programme. Responses will inform the design and participant support strategies for a future definitive trial.
Time frame: Baseline and 18 months
Research Composite Score (RCS)
An exploratory composite research index aggregating standardised scores across four domains already collected within the study: Physical activity domain-average daily step count and mean daily MVPA minutes, derived continuously from the Fitbit Charge 6 Self-reported symptom domain-scores from HADS, PSQI, WHOQOL-BREF, SCOPA-AUT, and Lawton iADL scale Sensory domain-UPSIT olfactory score adjusted for age and sex Digital engagement domain-Fitbit wear time, Slow-SPEED app opens, and Roche Mobile Application V2 completion rates Domain scores will be standardised and combined descriptively to characterise overall patterns of engagement and function across the study period. The RCS is a research-only instrument. No individual-level scores or predictions will be generated, communicated to participants, or used for clinical decision-making. Results will be used solely to inform the design of a future definitive trial.
Time frame: Baseline, 9 months, and 18 months
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