Background
Chronic low back pain (CLBP) is one of the most common chronic musculoskeletal disorders worldwide with a prevalence of 20%.1 Up to 85% of low back pain (LBP) diagnoses are non-specific, meaning no specific cause can be defined and management can be challenging.2 CLBP is currently ranked as the number one cause of disability.1 However, the magnitude of disability related to CLBP is not merely determined by the direct impact of pain and discomfort, but also by limitations in daily activities and societal participation.3 4 For instance, CLBP contributes to 13% of all causes of work absenteeism.5 In persons with CLBP, sleep disturbances and psychological factors such as anxiety and stress play a role.6 7 Since psychosocial and emotional factors are strong predictors of LBP chronicity, persons with CLBP may end up in a lifelong vicious circle characterised by invalidating pain, work absenteeism, physical deconditioning, sedentary lifestyle and comorbidities such as obesity or depression.2 8–10 As a result, CLBP has major socioeconomic implications and creates a burden on our healthcare system with global cost estimations rising substantially each decade.11 Optimised CLBP management through innovative research efforts is therefore essential.12
State-of-the-art guidelines recommend implementing exercise therapy (ET) in CLBP management.13 Nevertheless, treatment effect sizes in CLBP remain modest.13 Different factors may explain this.
First, many studies providing ET in CLBP started from the idea that the back should be treated carefully.14 15 This often results in exercise intensities below the required level for optimal treatment success and reinforcing anxious thoughts about loading the spine.16 Nevertheless, recent findings have demonstrated that high-intensity training (HIT) can be a valuable method to improve the effect sizes of concerning short-term and long-term disability and exercise capacity in persons with CLBP.17 18 However, the short-term and long-term effects of HIT in a large population with severe CLBP need to be investigated.
Second, it is striking to observe the lack of correlation between patients’ improvements in pain and disability after ET on the one hand and results on physical outcome measures such as endurance or strength on the other hand.19 This shows that ET effects in CLBP might not be directly or solely attributable to these changes in the musculoskeletal system.19 Substantial evidence now points out that ET provides multiple central effects such as psychological, (neuro)physiological and autonomic adaptations.20 21 In this regard, literature shows a positive effect of HIT on central sensitisation,22 mental well-being23 and adaptations of the cardiovascular system.24 Furthermore, there are indications that the implementation of sufficient exercise intensity and duration is related to better effects on pain.25 26 To date, it is unknown how ET can be optimised to improve and retain these central modulation effects maximally.
Third, many ET interventions used a pain-contingent approach (progress based on pain), as opposed to a time-contingent approach (progress over time regardless of pain) that is now advised in chronic pain,27 reinforcing again the message that the spine is vulnerable and that the exercise should be adapted or stopped in case of an increase in pain.28 A time-contingent HIT programme leads to significant short-term effect sizes to reduce disability in persons with CLBP.17
Additionally, long-term exercise programmes can lead to larger effect sizes for pain reduction and to an improved endogenous pain processing.29 30 Furthermore, it takes weeks to years to achieve behavioural change.31 From a feasible, cost-efficient perspective, longer ET protocols are preferably executed at home. However, such a training set-up requires clear guidance and support, as treatment compliance is low without it.32 33 For that reason, technology might support the treatment by encouraging persons with CLBP to keep performing their exercises in their own environment and prolong the rehabilitation process.34 For example, a video-based protocol is more effective in improving pain, function, kinesiophobia, expectations and several other factors than usual exercise practice at home.35 Still, it is unclear which duration leads to optimal improvement and the additional value of technology should be further investigated.36
Finally, although individualised exercises combined with education are recommended in chronic pain,14 37 clinicians often fail to implement this in clinical practice.19 Evidence shows altered brain structure and function in CLBP patients, and an approach including pain neuroscience education to cognitively prepare patients for ET is recommended.38 Additionally, exercises are often too uniform given the heterogeneity of CLBP patients.19 Therefore, many patients fail to adhere to their exercises, leading to poor treatment outcomes.39 Furthermore, the exercise intensity of these non-individualised exercises can, again, be too low for the specific individual. Individualised interventions and personalised guidance to increase patients’ adherence and to adapt the intensity accordingly need to be investigated to enhance therapy success.39
Therefore, the primary goal of this study is to evaluate the short-term and long-term effectiveness of a time-contingent individualised HIT protocol preceded by pain science education (PSE) on disability compared with moderate-intensity training (MIT) as used in usual care, in persons with severely disabling CLBP. Secondary goals entail evaluating (1) the short-term and long-term effectiveness of HIT on central effects such as psychological, (neuro)physiological and autonomic adaptations, and on broad physical fitness; (2) the additional effects of prolonged HIT at home; (3) the added value of technology through a mobile application that offers support during HIT home training and (4) cost-effectiveness of (technology supported) HIT compared with MIT.