Methods

A randomized, double-blind, placebo-controlled trial was performed. Postmenopausal women with knee OA were allocated to receive either CR (20 g� d (-1) for 1 wk and 5 g� d (-1) thereafter) or placebo (PL) and were enrolled in a lower limb resistance training program. They were assessed at baseline (PRE) and after 12 wk (POST). The primary outcome was the physical function as measured by the timed-stands test. Secondary outcomes included lean mass, quality of life, pain, stiffness, and muscle strength.

Results

Physical function was significantly improved only in the CR group (P= 0.006). In addition, a significant between-group difference was observed (CR: PRE= 15.7�1.4, POST= 18.1�1.8; PL: PRE= 15.0�1.8, POST= 15.2�1.2; P= 0.004). The CR group also presented improvements in physical function and stiffness subscales as evaluated by the Western Ontario and McMaster Universities Osteoarthritis Index (P= 0.005 and P= 0.024, respectively), whereas the PL group did not show any significant changes in these parameters (P> 0.05). In addition, only the CR group presented a significant improvement in lower limb lean mass (P= 0.04) as well as in quality of life (P= 0.01). Both CR and PL groups demonstrated significant reductions in pain (P< 0.05). Similarly, a main effect for time revealed an increase in leg-press one-repetition maximum (P= 0.005) with no significant differences between groups (P= 0.81).

Conclusions

CR supplementation improves physical function, lower limb lean mass, and quality of life in postmenopausal women with knee OA undergoing strengthening exercises.