Progressive high load strength training in patients with hypermobility spectrum disorders and shoulder complaints

Introduction
Joint hypermobility is characterised by the ability to move the joints beyond the normal range of motion. Symptomatic joint hypermobility is now called hypermobility spectrum disorders (HSD). At least four out of five patients with HSD experience
shoulder complaints, including persistent pain and mechanical shoulder symptoms (instability, subluxation, laxity). However, no studies have focused on exercise-based treatment for the shoulder in this patient group. Progressive high load strength training generally results in a marked increase in muscle cross-sectional area, neural drive, and increased tendon stiffness. These are essential components of acquiring active shoulder stability during movement tasks and daily life. Because patients with HSD often display decreased strength and increased shoulder laxity/instability, they may benefit from strengthening the shoulder muscles using progressive high load strengthening.
However, many clinicians hesitate to use high load exercise in patients with HSD due to uncertainty about patient safety, treatment effectiveness and because current guidelines recommend against high load exercise for this population. As such, no studies have assessed the effect of a progressive, high load strengthening programme on patients with HSD.

Objectives
The overall objective was to investigate patients with HSD and persistent shoulder complaints and the effectiveness of progressive high load strength training as treatment. The specific study aims were:

I) to investigate the feasibility of using progressive high load strength training among patients with HSD and persistent shoulder complaints. 

II) to develop and describe a study protocol including a progressive high load (HEAVY) and less progressive low load (LIGHT) shoulder strengthening exercise programmes, targeting patients with HSD.

III) to describe the shoulder impairments of patients with HSD, focusing on differences between patients with and without self-reported mechanical shoulder symptoms

IV) in a randomised controlled trial (RCT) to investigate the effectiveness of a 16-week HEAVY programme compared with LIGHT (usual care) in patients with HSD and persistent shoulder complaints seeking primary care. The main hypothesis was that HEAVY is superior to LIGHT in improving self-reported shoulder function. 

Methods
I) Patients underwent a HEAVY programme three times weekly using exercises targeting scapular and rotator cuff muscles. Primary outcomes were predefined research progression criteria, including recruitment rate, assessment duration, patient retention, training adherence, and adverse events, besides patient and physiotherapist feedback. Data were treated with descriptive statistics and paired t-tests.

II) A protocol for a high-quality superiority, parallel-group, RCT comparing HEAVY and LIGHT (usual care) was designed and described, including considerations about improved recruitment methods, sample size, and statistical methods.

III) Baseline data from the RCT was used. Medical history, self-reported and objective characteristics on shoulder pain, shoulder discomfort due to mechanical shoulder symptoms, shoulder function, fatigue, fear of movement, shoulder related quality of life, and additional treatment were collected by external blinded physiotherapists. Mechanical shoulder symptoms were defined as self-reported shoulder instability, subluxation, and/or laxity (rated as Yes/No). Data were treated with descriptive statistics and logistic regression analyses.

IV) Patients were randomised to receive a HEAVY or LIGHT three times weekly with exercises targeting scapular and rotator cuff muscles. The primary outcome was the between-group difference at 16-week follow-up in the Western Ontario Shoulder Instability Index (WOSI, 0-2100 better to worse) and self-reported and objective secondary outcomes. Data were treated with multivariable linear regression, multivariable logistic regression, generalised linear model, and quantile regression.

Results 
I) Twelve patients were included. The recruitment rate was 5.6/month, assessment duration (mean ± SD) 105 ± 9 min, retention 100%, adherence 83%, and four patients experienced short-lasting soreness or pain. Patient feedback was positive, and the physiotherapists found the intervention relevant and applicable to the patient group.

II) The HEAVY programme consisted of five shoulder exercises. A 5-repetition maximum (RM) test was conducted at the first session to estimate the 10 RM. The first three weeks consisted of a familiarisation period progressing from three sets of a load of 50% of 10 RM in week one, to 70% of 10 RM in the second week and to 90% of 10 RM in the third week. The following six weeks (weeks 4–9) included three sets of 10 RM, and from weeks 10–15, the training load was four sets of 8 RM. A tapering period was applied in week 16 to allow the anabolic response before follow-up testing. The LIGHT programme consisted of nine exercises. Phase 1 (weeks 1-4) consisted of isometric scapula setting; Phase 2 (weeks 5-10) included isometric shoulder exercises in a neutral position. In weeks 11-13, a combination of isometric and dynamic exercises midrange using a TheraBand. In Phase 3 (weeks 14-16), the exercises were dynamic to midrange. Patients in HEAVY were supervised twice weekly, and patients in LIGHT received supervision three times during the 16-week intervention. 

III) Sixty-seven of 100 patients reported mechanical shoulder symptoms. Patients in both groups said impairments related to shoulder pain, shoulder function, fatigue, fear of movement, and shoulder related quality of life. Patients with mechanical shoulder symptoms were younger (35.1 vs 43.3 years), had longer symptom duration (median 46 vs 24 months), reported a previous shoulder dislocation (25% vs 3%), experienced that their shoulder was loose (64% vs 15%), and reported shoulder discomfort due to mechanical shoulder symptoms (OR 1.48, 95% CI 1.17, 1.87). Furthermore, a larger proportion had received additional treatment (analgesic medication, steroid injection/surgery). 

IV) In the RCT, 93 of 100 patients (93%) completed the 16-week evaluation. The between-group difference in the mean WOSI score significantly favoured HEAVY (- 174.5 points, 95% CI -341.4, -7.7, adjusted for age, sex, baseline score, clustering around physiotherapy clinics). Patients in HEAVY were less likely to have a shoulder rotation test above 180° and more likely to rate an essential improvement of “physical symptoms” (Global Perceived Effect). However, most secondary outcomes were inconclusive. There were no serious adverse events, but patients in HEAVY reported more transient muscle soreness and headaches. The per-protocol analyses supported the main findings. The clinical relevance of the between-group difference remains unclear.

Conclusions 
The HEAVY programme was feasible and tolerable for patients with HSD and persistent shoulder complaints. A high-quality RCT comparing HEAVY and LIGHT programmes was designed, described, initiated, and completed with a final inclusion of 100 patients. At baseline, patients had substantial shoulder related impairments. Twothirds of the patients reported mechanical shoulder symptoms, and were younger and more severely impaired than those without mechanical shoulder symptoms. These findings highlight the importance of addressing mechanical shoulder symptoms during treatment to understand the patients’ shoulder impairments fully. At the primary endpoint 16 weeks postintervention, HEAVY was statistically superior to LIGHT and may be used as treatment in patients with HSD and shoulder complaints to alleviate symptoms and improve shoulder function in the short term. Patients should be supported to manage the associated transient soreness and headaches. However, further studies are needed to confirm the clinical relevance of the between-group difference, to explain the underlying mechanisms, and to evaluate the long-term effectiveness. A high load training protocol may potentially improve clinical practice and treatment of the critical and severe condition of HSD.