Technology Supported High Intensity Training in Chronic Low Back Pain: the Techno-HIT Trial

Chronic low back pain (CLBP) is one of the most common chronic musculoskeletal disorder worldwide and is responsible for the highest levels of disability of all diseases. All state-of-the-art guidelines recommend implementing exercise therapy (ET) in CLBP management. Researchers have shown that a novel ET modality, namely high intensity training (HIT), can be valuable. A clinical evaluation study in a larger spectrum of persons with CLBP in a rehabilitation centre setting is essential. Thereby, technology might support HIT.

The primary goal of this clinical trial is to evaluate the short- and long-term effectiveness of a time contingent individualized High intensity training (HIT) protocol on disability compared to moderate intensity training (MIT) in persons with severely disabling chronic low back pain (CLBP). Secondary goals entail 1) evaluating short- and long-term effectiveness of HIT on psychosocial correlates, central pain processing, and broad physical fitness, 2) investigating additional effects of (prolonged) HIT at home, 3) investigating added value of technology through a mobile (smartphone) and dashboard (computer) application that offers support during home training, 4) evaluating cost-effectiveness of (technology supported) HIT compared to MIT. The main research question\[s\] (RQ) it aims to answer are:

* RQ1: To what extent is HIT effective on the short- and long term to improve disability in persons with severely disabling CLBP compared to MIT as used in usual care?
* RQ2a: To what extent does HIT have a short- and/or long-term effect on central pain processing and psychosocial correlates in persons with severely disabling CLBP?
* RQ2b:To what extent does HIT have a short- and/or long-term effect on outcomes related to broad physical fitness in persons with severely disabling CLBP?
* RQ3a: To what extent does prolonged (technology-supported) HIT at home provide additional training effects in persons with severely disabling CLBP?
* RQ3b:To what extent does a mobile application that offers support for HIT at home provide added value for treatment outcomes of persons with severely disabling CLBP?
* RQ3c:To what extent is the techno-HIT application usable and qualitative (assessed by SUS and uMARS) as a therapeutic support mechanism, as evaluated by persons with severely disabling CLBP?
* RQ4: To what extent is HIT or HIT supported by a mobile application cost effective compared to MIT for patients with severely disabling CLBP?

This RCT includes a total sample size of n=168 persons with chronic low back pain (CLBP) randomly divided into three groups of each 56 participants (Group 1: 'TechnoHIT'; Group 2: 'HIT'; Group 3: 'MIT'). For each group, the trial involves a 24-week exercise intervention with a total of 52 rehabilitation sessions (4 educational sessions in the biopsychosocial program in the first two weeks and two physical therapy sessions each week (n=48 in total)) in three phases (2 therapy phases and 1 follow- up phase). The first therapy phase consists of 12 weeks and is performed in the hospitals (Jessa and UZA) under supervision of PhD-students (with a physiotherapy background) that are members of the FWO TECHNOHIT consortium and clinical study assistants (with a physiotherapy background). The second therapy phase consists of 12 weeks and is performed in the home setting of the participant. The follow-up phase only consists of advice towards continuation of physical activity and app logging or no contact based on group randomization. The first follow-up visit is planned directly after the last treatment session in the hospital. The second follow-up visit will take place 3 months after the last treatment session, shortly after the last at-home session. The last two follow-up visits will take place 6 and 18 months after the last at-home session.

Patients with CLBP who present themselves at UZA/Jessa for consultation and start-up of a rehabilitation program (i.e. within the Belgian reimbursement system for medical treatments defined as a 'K60 programma: Ambulante multidisciplinaire revalidatiezitting met een minimumduur van 120 minuten voor een wervelzuilaandoening') who ought to be eligible for the study by the physician (=who meet the inclusion criteria), will be informed about this study by the physician. If they are interested, a study flyer and an approval form for further contact will be issued by the physician. The form is signed by the patient and returned. The researchers will contact the potential participant within a period of two to seven days, answer initial questions, review the inclusion criteria, and provide the informed consent (online/hard copy according to the preference of the potential participant). Patients who sign and return the informed consent within two weeks will be contacted for possible enrolment.

This study will start recruitment in January 2024 and have an active intervention phase of three years. The end of the recruitment phase is therefore planned around January 2027. After the recruitment phase, a period of six months is reserved for final data analysis and scientific publication writing. The total duration of this study is therefore 3.5 years (the end of the study is expected around August 2027).

Pre-phase: biopsychosocial education program (4 sessions, T-1-T0):

Four sessions with educational content (60 min./session, 2x/week) will be organized at the hospitals at the start of the intervention for all groups. This educational content relates to a) pain education/dealing with pain, b) ergonomics, c) activity management and optimizing the working and social environment, and d) neurophysiology of pain. These sessions will be provided by the PhD students. The content of this education program is based on scientific research and publications on patient education from renowned organizations such as retrainpain.org and pain in motion and on extensive work previously done by members of the consortium. The content will be standardized between the test centers UZA and Jessa.

Phase 1: intervention at the hospital facility (24 sessions, week 1-12, T0-T1) The three groups will follow a 12-week training program in which a time contingent approach is used as proposed by recent clinical practice guidelines. To limit performance bias, each group will train separately and will not be able to evaluate differences between the therapies.

Group 1 ('TechnoHIT') and group 2 ('HIT') - These groups will perform 1,5h exercise therapy sessions twice a week comprising of a combination of cardiorespiratory interval, general resistance, and core muscle strength training, all at high intensity, according to a previously published protocol by our research group. Briefly, cardiorespiratory training consists of an interval protocol on a cycle ergo-meter consisting of five one-minute 100% VO2max workload bouts, separated by one minute of active rest at 50% VO2max workload. 100% VO2max bouts increase every two sessions by 10''. Active rest remains stable. This protocol is repeated from session 13 to 24 with an updated workload (+5% WMax). General resistance training consists of three upper body and three lower body exercises executed on fitness equipment performed at 80% of the one repetition maximum. Core muscle strength training consists of six static core exercises and related progressions. Exercises were chosen in function of their ability to load the core muscles at an intensity of \>60% of the maximum voluntary contraction.

Group 3 ('MIT', control group) - This group will perform 1,5h exercise therapy sessions twice a week of cardiorespiratory continuous load, general resistance and core muscle training, all at moderate intensity, according to a previously published protocol by our research team. Briefly, cardiorespiratory training consists of a continuous training protocol on a cycle ergometer. Participants start with 14 minutes of cycling (90 repetitions per minute at 60%VO2max workload). Duration will be increased every two sessions with 1'40'' up to 22'40''. This protocol is repeated from session 13 to 24 with an updated workload (+5% WMax). General resistance training is identical to the protocol described in 'HIT' with the exception of the exercise intensity (exercises are performed here at 60% of 1RM). Core muscle strength training is identical to the protocol described in 'HIT' with the exception of the exercise intensity. Participants perform one set of ten repetitions of a ten second static hold. Exercises are made more difficult when they were executed with a stable core posture for the indicated time by increasing the time of the static hold each six sessions.

Phase 2: intervention at home (24 sessions, week 13-24, T1-T2) The three groups will follow a comparable 12-week training program as phase 1 but in their home setting. The participants of group 1 will be supported by a mobile application on their phone. The participants of group 1 \& 2 will be provided with a fitness bike, a smartwatch (Polar M200), and training mat during the execution of this phase. Sessions missed by the participants because of adverse events (e.g., acute increase of low back pain, acute musculoskeletal issues due to exercises) will be registered.

Group 1 ('TECHNO-HIT') - Participants in this group receive an exercise schedule via the TechnoHIT mobile application, a home trainer (E50, Tunturi Fitness), a heartrate sensor (H10, Polara) and smartwatch (Ignite, Polar), and a training mat for the duration of this phase. They are asked to perform a 60 min. home program twice a week containing cardiorespiratory and core muscle strength training, both at high intensity (HIT protocol methods are equal to those in Phase 1). The training sessions of these patients are guided by the mobile application. The user reports performes exercises in the mobile application, that keeps track of their progress, calculates compliance with the program and gives motivational feedback based on the patient's performance and adherence.

Group 2 ('HIT') - Participants in this group receive an exercise schedule on paper, a home trainer (i.e. fitness bike) and a training mat for the duration of this phase. They are asked to perform a one-hour home program twice a week containing cardiorespiratory and core muscle strength training, both at high intensity. They also receive a diary to log their training sessions.

Group 3 ('MIT', control group) - Participants in this group receive an exercise schedule on paper. They are asked to perform a one-hour home program twice a week containing cardiorespiratory and core muscle training, both at moderate intensity. They also receive a diary to log their training sessions. As we decided not to provide a bicycle and exercise mat in order to match the "therapy as usual" setting, cardiorespiratory training in this phase will be based on a brisk walking modality performed at the same moderate exercise intensity and matched for training volume.

The Techno-HIT home-training system consists of the following components and main functionalities:

* a mobile application for the patients at home (to receive the HIT training program, to schedule the training in sessions over the week, to receive reminders and notifications, to see the overall HIT training program or get more details on exercises and performed sessions, to have access to exercise instructions, to get guidance by the app while performing the exercises, to get motivational feedback after performing the exercise and reporting the status, to get feedback about progress and adherence, to select a strategy to improve the adherence, to report a variety of activities beyond the HIT program, etc.);
* a dashboard application for the physiotherapists / researchers (to see an overview of notifications about the patient's training status, to search through patient files and notifications, to manage patient groups, to provide the info on the HIT training, to update exercise parameters, to follow-up on the patients' progress and view aggregated visual representations of progress, to send hints to the patients, to follow system suggestions for a progression or regression, to give feedback to patients). Some functionalities are "admin" functionalities and require an authorized account (e.g. to create new patient files, to manage caregiver accounts, etc.).

Participants perform two assessments at baseline (T-1: PRE before psychosocial education \& T0: PRE after psychosocial education), and 4 longitudinal assessment (T1: MID after a 12-week program in-hospital, T2: POST after a 12-week program at home, T3: POST 6 month follow-up, T4: POST 18 month follow-up) consisting of both physical testings and filling in health and disease related questionnaires. At T-1, the assessments have a duration of approximately 2 hours (90min questionnaires + 30min QST measurements). During this assessment, sociodemographic data of the participant will also be collected. At T0, physical assessments will be added, aswell as additional questionnaires. T0 will have a duration of approximately 3 hours. At T1, T2, T3 and T4, additional questionnaires will be added, increasing the duration to 3 hours and 40 minutes.

A rater cross-over assessment protocol will be used to ensure blinding of assessors. All assessments are carried out by trained PhD-students and postdoctoral researchers that are part of the FWO Techno-HIT Trial project in the specialized movement and pain assessment labs of REVAL, UHasselt and MOVANT, UAntwerpen. (see section outcomes for detailed information on the depicted outcome measures)

All data is treated confidentially and encrypted during the execution of the tests ('HIT-TECH', followed by a timing letter/number (T-1 =A, T0=0, T1=1, T2=2, T3=3, T4=4) and a sequence number (01 to 15)). To associate the data with the subjects during data analysis, a subject identification list (0-15, randomized) is used. The identification and key of the code is monitored by an independent researcher who is not involved in the research. All data collected is stored in the Google Drive (UHasselt)/Microsoft Teams (UAntwerp) file stream and only members of the research team with a university account and password can access the source data. Source data is kept for 25 years in accordance with GCP standards for reuse or for results validation.

Eligibility Criteria:
Inclusion Criteria:

* speak Dutch
* be 18 to 65 years old
* have nonspecific CLBP defined as chronic primary musculoskeletal pain (ICD-11: MG30.011) in the low back persisting for at least 12 weeks12, whereby fluctuations in pain can be present and pain can be alternated by remission phases. Furthermore, regarding the specification of 'severity', only participants with a profile consisting of a score of \>20% on the Modified Oswestry disability Index (i.e. 'moderate disability') will be included.
* have and make use of a working iOS/Android smartphone

Exclusion Criteria:

* when they have had spinal fusion surgery
* when they have a musculoskeletal and/or chronic disorder aside from CLBP that could affect the correct execution of the therapy program or evaluation of the outcomes
* when they have severe comorbidities (e.g., paresis or sensory disturbances by neurological causes, diabetes mellitus, rheumatoid arthritis)
* when they are pregnant
* when they have ongoing compensation claims
* when they are not able to attend regular therapy appointments