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Exercise and osteoarthritis.

To the Editors: Dr. Charlson and her colleagues have made an important contribution toward understanding the rational use of exercise for osteoarthritis (1). However, their statement that "sessions included light stretching and strengthening exercises" merits some elaboration. Stretching and strengthening have many descriptors in addition to light (for example, isometric, maximal contraction, passive, and so forth) (2). Furthermore, various types of stretching and strengthening may be effective in arthritis treatment (3, 4) independent of ambulation. Perhaps the authors could elaborate on the nature of the light stretching and strengthening in their study and their relevance to its outcome.