Blood-flow Restricted Exercise in Inclusion Body Myositis

Low-intensity Blood-flow Restricted Muscle Exercise in Patients With Sporadic Inclusion Body Myositis: a Randomised Controlled Trial

This study evaluates the effects of a low-intensity blood-flow restricted exerciser protocol on patient reported physical function, in patients with sporadic inclusion body myositis. The study is designed as a parallel group randomized controlled trial with a treatment group and a control group.

Sporadic inclusion body myositis (sIBM) is a disease characterized by skeletal muscle inflammation and severe muscle atrophy especially in the muscles in the thigh and the finger flexors. In time the muscle weakness will cause the affected person to become unable to walk and carry out basic tasks in the every day life. Currently no effective treatment exist for sIBM patients, however several studies indicate that exercise may be beneficial for the patients. In the resent years a lot of research attention has been directed toward low-intensity training with partial vascular occlusion as an alternative to the conventional high intensity strength training. Interestingly the low-intensity blood-flow occluded training is found to be at least as beneficial in causing muscle growth as the conventional strength training but with very little mechanical load on joints and tendons. Furthermore the blood-flow occluded training seem to result in a hyper-activation of muscle stem cells which play an important role in muscle regeneration. This make the blood-flow restricted training modality a very interesting treatment possibility for sIBM patients because it might be able to restore and/or maintain the skeletal muscle tissue and therefore also muscle function.

Participants will receive care as usual (various DMARDs, different from patient to patient) + 12 wks of low-intensity blood-flow restricted training twice per week.

The intervention consists of low-intensity blood-flow restricted training involving 5 lower extremity exercises performed uni lateral in four sets to concentric failure with an intensity of approximately 25 repetition maximum (25RM).

The intervention consists of various DMARDs, which are given to the patients depending on their physical state and the disease activity.

Patient reported physical function will be evaluated with the short form (36) health survey (SF-36) subscale: Physical Function. The scale ranges from 0 to 100 where 100 is the highest score.

An assessment tool used by the physician to evaluate disease activity in various organ systems via a scoring system and VAS scales.

An assessment tool used by the physician to evaluate the damage caused by the disease or co-morbid conditions, to various organ systems. The system uses VAS scales.

A 2-min maximal walk test where the participant is encouraged to cover the greatest distance possible.

Participants are instructed to rise from a chair walk 3 m forward, pass a marking and return to the chair and sit down as fast as possible

HAQ is a questionnaire to evaluate patient reported disability. It has 8 categories with a range of questions. Each question is scored from 0 to 3 where 0 is no disability and 3 is unable to do.

Muscle biopsies will be taken on a selected number of subjects from either the vastus lateralis or the tibialis anterior muscle, for the use in future analysis of i.e. muscle fibre size and distribution, myogenic stem cell activity, capillary density, muscle inflammation ect.

The maximal isometric and dynamic knee extension muscle strength will be evaluated in a Kin-Com dynamometer. Isometric strength data will be analyzed for peak torque, maximal impulse and maximal contractile rate of force development (RFD)

The Nottingham Power Rig is used for evaluating the maximal muscle power that can be generated in the leg extensors.

Inclusion Criteria: Clinical features Duration of weakness > 12 months Weakness of finger flexors > shoulder abductors AND knee extension > hip flexion Pathologic features Invasion of nonnecrotic fibres of mononuclear cells or rimmed vacuoles or increased major histocompatibility complex I (MHC-1) but no intracellular amyloid deposits or 15-18nm filaments Exclusion Criteria: Lack of gait function Co-morbidity contraindicating the use of blood-flow restricted training (previous deep vein thrombosis/pulmonary embolism or known peripheral ischemic disease). Co-morbidity preventing resistance training (severe heart/lung-disease, uncontrolled hypertension (systolic > 160mmHg, diastolic > 100mmHg), severe knee/hip arthritis)

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