The aim of the present study is to evaluate the effects of WB-EMS application in overweight women and men with knee osteoarthritis, with special consideration of sustainability. In this randomised controlled trial 72 overweight patients with knee osteoarthritis aged 40-70 years will be included and randomly assigned to two groups (WB-EMS vs. control group (CG)). The intervention group will perform six WB-EMS sessions/month of 20 min for 6 months. An intermittent low frequency WB-EMS-protocol with an impulse phase of 6s, followed by an impulse break of 4s will be applied. The control group will undergo a tailored physiotherapy program of 6 sessions defined as usual care. In addition, both groups will complete a self-management training programme for osteoarthritis of 6 sessions over 12 weeks.

Studies consistently show a positive effect of strength training on pain and function in knee osteoarthritis. In addition to local neuromuscular effects, systemic mechanisms that modulate inflammatory processes are increasingly being discussed as mechanisms of action. Overweight and obesity might be involved in this process. Despite high evidence, unfortunately only few people with osteoarthritic knee pain are willing or able to perform conventional muscular strength training on a regular basis. In this context, whole-body electromyostimulation (WB-EMS) is a time-efficient, joint-friendly and subjectively less strenuous training alternative. In WB-EMS, all large muscle groups of the body are simultaneously activated and brought to contraction by electrical impulses. Together with easy movements with minor mechanical stress on the knee joint, the additive WB-EMS activates muscle contraction and results in measurable muscular effects.

The aim of the present study is to evaluate the effects of a 6-month WB-EMS application in overweight women and men with knee osteoarthritis, with special consideration of sustainability. In this randomised controlled trial (RCT) 72 overweight patients (BMI >25 kg/m2) with knee osteoarthritis (radiographic severity Kellgren-Lawrence 2 and 3) aged 40-70 years will be included and randomly assigned to two groups (WB-EMS vs. control group (CG)). The intervention group will perform six WB-EMS sessions/month of 20 min for 6 months. An intermittent low frequency WB-EMS-protocol (85 Hz, 350 µs) with an impulse phase of 6s, followed by an impulse break of 4s will be applied. The control group will undergo a tailored physiotherapy program of 6 sessions defined as usual care. In addition, both groups will complete a self-management training programme for osteoarthritis of 6 sessions over 12 weeks.

At baseline, after 6 months of intervention and after a further 6 months of follow-up, knee pain and function will be determined by the KOOS instrument (Knee Injury and Osteoarthritis Outcome Score). Functional tests and isokinetic leg strength measurements will also be performed. In parallel, MRI assessments are applied to quantify effects on joint structure (whole organ assessment; MRI Osteoarthritis Knee Score (MOAKS)) and visceral fat as well as muscle quality changes at the mid-thigh. Whole body composition analyses are performed using segmental whole-body bioimpedance analysis (BIA) for quantification of body fat and fat-free mass. Blood samples are obtained at baseline, 6 and 12 months to determine inflammatory biomarkers (CRP, IL-1beta, MMP-3) and cartilage formation (PIINP).

The study will provide evidence and detailed insights of the WB-EMS induced effects on pain, function, muscle structure and strength, body composition, joint tissues and anti-inflammatory effects in knees with osteoarthritis. From a clinical perspective, the study will provide important information regarding a promising non-pharmacological therapeutic approach for the treatment of knee osteoarthritis.

Inclusion Criteria:

• overweight (BMI>25 kg/m2)
• radiographically confirmed early to moderate femorotibial osteoarthritis (Kellgren- Lawrence grades 2 and 3)
• osteoarthritic knee pain for at least 3 months
• average pain intensity > 2.5 (NRS 0-10)

Exclusion Criteria:

• WB-EMS in the last year or resistance exercise >1 session/week in the last year
• present glucocorticoid or opioid medication
• trauma of the knee joint within the last 3 months
• intra-articular injections in the knee joint within the last 3 months
• malignant diseases
• serious cardiovascular diseases
• conditions or diseases that are contraindications for WB-EMS
• absence ≥3 weeks during the intervention period