Background: Due to fear of injury and risk of fractures, many people with osteogenesis imperfecta (OI) avoid vigorous exercise that is likely to improve muscle and bone weakness common in this disorder. Low-intensity muscle strength training with blood flow restriction (BFR-LI) via an inflatable cuff leads to similar improvements in muscle size and strength to conventional high-intensity strength training but has not been applied in OI.Objectives: To evaluate the effect of BFR-LI on muscle and bone health and quality of life in adults with OI type I.Methods: For this randomized controlled trial, 40 adults (18-65y) with OI type I will be recruited. Exclusion criteria include pregnancy or \<6 months postpartum, deep vein thrombosis, acute fractures, recent surgery, regular vigorous exercise, or contraindications to exercise. Participants will be randomly assigned to perform BFR-LI or standard care. The BFR-LI group will perform home-based exercises 2-3 times/week for 12 weeks at low training intensity (20% of 1-repetition maximum) which will increase every 4 weeks. Muscle and bone parameters will be evaluated using scans (peripheral computed tomography and dual-energy x-ray absorptiometry) and muscle strength tests, and quality of life (mental well-being, participation, pain and fatigue) by the PROMIS questionnaire at baseline, immediately, three, and six months after training.
Osteogenesis imperfecta type I, aged between 18 and 65 years old
Pregnancy/<6 months postpartum
Deep vein thrombosis (now or history of)
Cardiovascular, respiratory, or neuromuscular diseases
Recent cardiovascular events/untreated hypertension
Parallel
Blood flow restriction training
Other interventionThe validated Smartcuffs PRO will be used. Maximal occlusion pressure (MOP), i.e., the pressure needed to fully occlude blood flow in the limb, is determined using a pulse pressor sensor while lying. 80% of the MOP is used for the training, achieving partial arterial occlusion and total venous occlusion. Resistance exercises (squats, hamstring curls, toe stands) are performed at 20% 1RM and in 4 sets (1x30, 1x15, 1x15, and 1x until failure). Participants will perform the 12-week training program from home, for 2-3x per week with a minimal 48-h interval between each session. After 12 weeks, they have the possibility to train for another 12 weeks (so 24 weeks in total). After each 4 weeks of training, 1RM estimates will be remeasured, to ensure progression of the training. Participants in the control group will have the option to switch to the training group after 6 months. They will be followed up for 6 months (same protocol as intervention group, though without the 9 month-follow-up).
Muscle mass
Subtotal lean mass (whole body minus head; kg), lean mass of both legs, and arms (as control parameters that could assess any systemic effects of the training) will be measured by dual energy X-ray absorptiometry (DXA; Hologic QDR- Discovery device; software version 2.3.1; Hologic, Bedford, MA, USA).
Other muscle parameters: muscle strength measurements
Indirect 1RM measurements (via 20RM; dynamic muscle strength; kg) of quadriceps (squats), hamstrings (knee flexion), and calves (toe stands)
Other muscle parameters: muscle strength measurements
Handheld dynamometry of quadriceps, hamstrings, and calves (isometric muscle strength; N).
Other muscle parameters: muscle strength measurements
Peak power (kW) during the chair rise test, single two leg jumping, and heel rise test (mechanography; Leonardo Mechanograph; Novotec Medical Inc., Pforzheim, Germany; dynamic muscle strength).
Bone parameters
Bone mass (bone mineral content, g) will be determined through whole body/lumbar spine/bilateral femoral neck DXA measurements and 3D shaper-software (3D-shaper Medical 2025).
Feedback training
Participants will be asked for feedback on the training to optimize its implementation in future in clinical practice. We will do this by one-to-one semi-structured interviews. All interviews will be conducted face-to-face. Open-ended questions will be used to understand the experiences of the participants.
Physical activity
Physical activity will be measured through the International Physical Activity Questionnaire (IPAQ). This questionnaires measures activity in minutes/week and Metabolic Equivalent of Task (MET)-minutes/week. Based on MET-minutes/week, activities are categorized in light, moderate or vigorous activity. Scores (min/week for each activity, MET-min/week for each activity and total MET-min/week) range between zero and unlimited. The higher the scores, the more active the participant. Additionally, participants will be asked to report any changes in participation to vigorous exercise.
Number of patients with changes in participation to exercise
Participants will be asked to report any changes in participation to vigorous exercise during the study
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University Hospital, Ghent
Lead sponsor
Brittle Bone Society
Collaborator
Osteogenesis Imperfecta Federation
Collaborator
University Ghent
Collaborator
