Platform Exercise Training

Osteoarthritis (OA) is the most common disabling disease in older adults,(1) affecting over
25 million Americans, resulting in significantly impaired function and mobility(2) and a
societal economic burden.(3) The knee is the weight-bearing joint most commonly
affected,(10) and the prevalence of symptomatic knee OA is between 9% and 21% among those 65
years and older.(2, 11, 21) Loss of knee range of motion can lead to significant difficulty
in bathing, lower body dressing, stair mobility, and walking.

Impaired mobility due to knee OA will have an increasingly significant societal impact, with
67 million adults projected to have arthritis by 2030, and 25 million with
arthritis-attributable activity limitations.(22) Women are at greater risk for knee OA
compared with men. Knee OA leads to chronic disability,(23-25) functional limitations,(26)
and dependence.(27) Patients with knee OA frequently are limited in their activities by
joint stiffness or buckling, decreased range of motion, muscle weakness, poor balance,
impaired proprioception, reduced vibration sense, and/or pain. Currently, there are limited
options available for patients for improving the outcome of knee OA once they have it. At
this time, patients may use analgesics for pain with total knee replacement as the last
option. However, we recently found that greater quadriceps strength protected against the
development of incident symptomatic knee OA and progression of knee OA in women.(19-20)
Thus, strengthening the quadriceps muscle may prevent worsening of the knee joint. Though
before studying whether strengthening is effective in reducing risk for knee OA, it is
necessary to first determine an effective and tolerated means of exercise.

Vibration platform exercise may provide the benefits of strength training without adding
potentially harmful loads to the knee joint. In one study of nursing home residents with
limited functional capacity, balance and mobility improved over a 6-week whole body
vibration exercise program. (12) In another study that compared whole body vibration (WBV)
to resistance training in older women, greater improvement in knee extensor strength and
speed of movement was found with WBV exercise.(13) Additionally, after a 2-month exercise
program with older adults between the ages of 59 to 86, walking speed, step length, and the
maximum standing time on one leg significantly improved with WBV exercise.(14) WBV exercise
was safe and well tolerated in the elderly.(14, 15, 16) There have also been indications
that WBV may improve flexibility. While a study testing range of motion (ROM) found that
both the WBV and the control groups had significant increases in hamstring flexibility, only
the WBV group showed a significantly larger increase (30%) in ROM than did the control group
(14%).(17) There have also been indications WBV may improve proprioception (joint position
sense) in women with knee osteoarthritis. One study which compared control versus exercise
on a vibration platform and a balance board vibration platform found improvements in muscle
strength and proprioception, respectively.(18) Thus, these studies suggest a beneficial
effect of WBV exercise in addition to muscle strengthening, balance, and walking exercises
in improving the walking ability in the elderly.

Exercises conducted on a vibrating platform will induce a muscle reflex, increasing muscle
fiber activation at a higher level compared to performing the exercises on a non-vibrating
platform. We have selected the frequency and duration of this program based on 1) frequency
used in previous studies and recommended by the manufacturer and 2) duration of 12 weeks
based on previous data which found the most gain in knee extensor strength and speed of the
movement occurred at week 12 of a 24-week program. (13)

Vibration exercise may be a better option than strength training alone, if the exercises can
be completed in less time and with similar strength gains as resistance training, but
without the additional loads contributing to the stress on patients' joints.