Strengthening Exercise and Quadriceps Force During Walking

This is a longitudinal, randomized, controlled interventional multi centric study on the effects of lower leg strengthening exercise on quadriceps force during walking in people with knee osteoarthritis. At each study centre twenty subjects will be included, for a total of 40 participants. Subjects will be randomized equally (1:1) into 1 active arm and 1 control arm.

The objective of the study is to evaluate the effect of twelve weeks of quadriceps strengthening on the mechanical output of the quadriceps during locomotion. A secondary purpose is to explore the relationship between quadriceps strengthening and compressive knee loadings. The hypothesis is that quadriceps strength training will not change quadriceps force, power, and work in locomotion in people with knee osteoarthritis.

Primary outcome is quadriceps force during walking, secondary outputs are quadriceps power and work and knee compressive loads during walking. Explorative measures are isometric and concentric isokinetic leg muscle strength, radiographic score of the knee (Kellgren and Lawrence), a one-leg rise from chair test (maximum number of reps) and a lateral step-up test (maximum number of reps).


Eligibility Criteria:
Inclusion Criteria:

A medical doctor will perform the screening of potential participants. Subjects must meet the following inclusion criteria to be eligible for study entry:

* Knee OA diagnosed according to the American College of Rheumatology criteria (26), with clinical symptoms and radiographically verified tibio-femoral osteoarthritis in one or both knees.
* Aged between 40 and 65 yrs.
* Untrained (i.e. less than 2 hours of exercise per week)
* Subject must not be using assistive walking device
* Willing and able to complete study visits and procedures
* Willing to hold activity and exercise level generally consistent during the study except that encompassed in the study.
* In general good health, in the opinion of the investigator, based on medical history and physical examination and, if necessary, laboratory values. Laboratory tests are prescribed by the medical doctor at the screening visit.
* A body mass index (BMI) of 19\<BMI≤32kg/m2
* Speaks, reads and writes Danish and/or English language

Exclusion Criteria:

Subjects who meet any of the following exclusion criteria will be ineligible for study entry:

* Subjects depending on walking device
* Pregnant or breastfeeding
* Radiographic evidence of Patello-femoral knee OA only (and no tibio-femoral OA).
* History of symptoms of autoimmune disorders (e.g., inflammatory bowel disease, multiple sclerosis, lupus, rheumatoid arthritis)
* Planned surgical procedure during the duration of the study
* History or diagnosis of musculoskeletal injuries or pathologies, including but not limited to:

  * Anterior cruciate ligament injuries
  * Meniscal injuries related to trauma (degenerative changes allowed)
  * Patellofemoral Pain Syndrome
  * Low back pain
* History, diagnosis, or signs and symptoms of clinically significant cardiovascular disease, including but not limited to:

  * Ischemic heart disease
  * Arthrosclerosis
  * Peripheral artery disease
* History, diagnosis, or signs and symptoms of diabetes
* History, diagnosis, or signs and symptoms of neurological disorders including but not limited to

  * Stroke
  * Parkinson's disease
  * Multiple sclerosis