Author (year) Assessments Outcomes Adverse effects Song et al. (2003) [15 ] WOMAC (pain/stiffness/physical function); knee extensor strength and endurance; flexibility; BMI; cardiovascular functioning test Knee extensor strength and endurance, flexibility, cardiovascular functioning test were improved BMI and WOMAC were decreased No adverse event Brismée et al. (2007) [16 ] WOMAC (pain/stiffness/physical function); VAS; knee range of motion WOMAC and VAS were decreased No adverse event Song et al. (2007) [17 ] WOMAC (pain/physical function); motivation; health behaviors Motivation and health behaviors were improved WOMAC was decreased No adverse event Lee et al. (2009) [18 ] WOMAC (pain/stiffness/physical function); SF-36; 6-min walking test SF-36 and 6-min walking test were improved WOMAC was decreased No adverse event Song et al. (2009) [19 ] WOMAC (pain/stiffness/physical function); Survey of Activities and Fear of Falling in the Elderly WOMAC was decreased Survey of Activities and Fear of Falling in the Elderly was improved No adverse event Wang et al. (2009) [20 ] WOMAC (pain/stiffness/physical function); VAS; SF-36; BMI; 6-min walking test; sit-to-stand test; Center for Epidemiology Studies Depression Index; self-efficacy 6-min walking test, sit-to-stand test, SF-36, self-efficacy were improved WOMAC, VAS, Center for Epidemiology Studies Depression Index were decreased One participant reported an increase of knee pain Ni et al. (2010) [21 ] WOMAC (pain/stiffness/physical function); 6-min walking test; stair climb test; body weight 6-min walking test, stair climb test, body weight were improved WOMAC was decreased No adverse event Song et al. (2010) [22 ] Bone mineral density; knee extensor and flexor strength and endurance; Survey of Activities and Fear of Falling in the Elderly Knee extensor endurance was increased Bone mineral density and Survey of Activities and Fear of Falling in the Elderly were improved No adverse event Tsai et al. (2013) [23 ] WOMAC (pain/stiffness/physical function); timed-up-and-go test; sit-to-stand test; mini-mental state examination Timed-up-and-go test, sit-to-stand test, mini-mental state examination were improved WOMAC was decreased No adverse event Wortley et al. (2013) [24 ] WOMAC (pain/stiffness/physical function); BMI; 6-min walking test; timed-up-and-go test; stair climb test; Physical Activity Scale for the Elderly Physical Activity Scale for the Elderly, 6-min walking test, stair climb test, timed-up-and-go test were improved WOMAC was decreased No adverse event Tsai et al. (2015) [25 ] Verbal descriptive scale; pain behavior Verbal descriptive scale and pain behavior were decreased No adverse event