gms | German Medical Science

Objective: Lower-extremity strength deficits are commonly reported in women with knee osteoarthritis (OA) or total knee arthroplasty (TKA), and may markedly reduce functional capacity and balance [1]. Resistance exercise (RE) is an effective method to improve muscle mass and strength [2], [3]. However, little is known about musculoskeletal adaptation to RE in TKA and knee OA patients. Our purpose was to analyze musculoskeletal adaptation to RE in older women with TKA and knee OA.

Material/Methods: Seven older women with TKA and knee OA in the contralateral limb (OKG; 75.3±3.1 years), and sixteen older (OG; N=8; 64.4±6.5 years) and young (YG; N=8; 23.9±3.8 years) women without musculoskeletal limitations underwent a twice-a-week RE program for 13 weeks (2 sets of 8 to 12 repetitions of unilateral leg press, knee curl and calf raise exercises in both legs). Initial RE intensity was set at 60% of 1 repetition maximum (1-RM) strength of the weaker leg, and it was increased in 5% to 10% each time 2 sets of 12 repetitions were performed in a determined exercise (both legs). Muscle strength was assessed before and after RE program by 1-RM strength test.

Results: OKG displayed lower (P<0.01) baseline 1-RM strength than OG (27.7±10.11%) and YG (57.4±11.75%), and baseline 1-RM strength of OKG was lower (P=0.007) in the OA (2.88±0.47 kg.kg-0.67) than TKA leg (3.75±0.41 kg.kg-0.67). Muscle strength improved significantly after RE training in all groups (P<0.001); however, 1-RM strength increase of OKG was greater (P<0.05) in the OA (62.2±11.6%) than TKA leg (38.9±6.0%), and greater than YG (25.2±11.9%) and OG (37.7±20.7%) increase. The greater RE induced 1-RM strength increase of OA leg reduced the 1-RM strength deficits between legs in OKG (23.4±7.4% vs. 10.8±7.7%, P=0.02). OKG also displayed greater RE intensity progression than YG and OG at leg press (OKG=103.6±33.6%; OG=36.6±17.8%; YG=40.0±16.9%; P<0.001) and calf raise (OKG=80.1±21.2%; OG=40.4±12.4%; YG=32.4±13.9%; P<0.05), and greater than YG at knee curl (OKG=142.2±42.6%; YG=43.1±17.4%; P<0.01).

Conclusion: The OA leg of OKG diseplayed greater RE-induced muscle strength than TKA leg of OKG, and both legs of OG and YG. OKG also showed greater RE intensity progression than OG and YG. These results suggest that RE is an effective method to counteract the lower-extremity strength deficits reported in women with knee OA and TKA.