Work Group recommendations: 2002 Exercise and Physical Activity Conference, St. Louis, Missouri

Session III, Biomechanical Considerations for Exercise

Work Group members: David Krebs, PhD, PT, Massachusetts General Hospital, Boston, (Chair); Walter Herzog, PhD, University of Calgary, Alberta, Canada; Chris A. McGibbon, PhD, Massachusetts General Hospital, Boston, Massachusetts; Leena Sharma, MD, Northwestern University, Evanston, Illinois


There is not enough fundamental information on the biomechanical consequences of arthritis. Based on current knowledge, we offer the following recommendations:

  • 1Eliminate extreme inactivity, and promote at least moderate exercise and physical activity, in children and adults of all ages to:
    • Prevent the loss of proteoglycans that results from immobilization. Immobilization results in loss of cartilage and may also adversely affect bone mineral density;

    • Eliminate compensations at other joints, which may lead to muscle and whole-body biomechanical abnormalities such as asymmetrical loading, poor segment alignment (posture), and uncoordinated patterns of the joints and limb segments (inefficient energy transfer);

    • Strengthen muscles and enhance muscular coordination; and

    • Emphasize preventive measures for both overuse (joint injury) and underuse (inactivity).

  • 2Exercise recommendations should be specific to the arthritis (e.g., acute/chronic osteoarthritis; juvenile rheumatoid arthritis, rheumatoid arthritis) subset because so little is known about the biomechanical issues related to these different subsets, but the following appear to be biomechanically most relevant to exercise prescription:
    • anatomic (e.g., alignment, compartment involvement)

    • body weight

    • baseline muscle status

    • quantitative gait characteristics

    • type of activity, (e.g., gardening [bending, crouching, kneeling], competitive and leisure sports [high impact, high injury risk], mechanical labor [bending, lifting, climbing])

Research Agenda

Little fundamental biomechanical information exists about arthritis. The field needs more research on:

  • 1Effects of tissue loading
    • How do tissues adapt, positively or negatively, to mechanical loading?

    • What are the effects of everyday loading in normal tissues and in all stages of disease?

    • What are the effects of exercise-induced loading in normal tissues and at all stages of disease?

  • 2In vivo load data from humans on:
    • Loading during activities of daily living

    • Loading during exercise interventions

    • Aging and natural history of disease within subsets as listed above

    • Effects of knee compartment involvement, especially upon alignment

    • Joint involvement

    • Alignment and effects of interventions (e.g., foot orthotics)

    • Joint laxity

    • Effects of increased (or decreased) body weight

    • Muscle strength changes

    • Gait characteristics (mechanistic [characterize loading abnormalities and compensations], prognostic [predict disease progression]

    • Mechanical risk factors for incident and progressive arthritis

  • 3Appropriate exercise interventions and physical activity recommendations for specific subsets
  • 4Long-term outcomes from exercise trials categorized and reported by: symptoms, structural outcome (radiographic, magnetic resonance imaging), long-term functional outcomes (measures of joint physical function, gait and other locomotor activities of daily living) and disability