Korean Journal of Geriatrics & Gerontology

Table. 1.

Table. 1. Table 1

Characteristics of the studies included in this systematic review

Author (year)	Participants (age，sex)	Inclusion criteria of participants	Intervention	Outcome variables (ES of relevant outcomes)
Experimental group (n)	Control group (n)
I. Stretching exercise vs. no exercise
Aoki et al. [8] (2009)	67 to 82 years All females	Diagnosed with severe KOA by radiographs	Home based self-stretching (n=17) Stretching method: seated quadriceps stretching and prone rectus femoris stretching	No intervention (n=17)	Pain (VAS) [0.20] Supine-ROM [0.20] Gait-ROM [0.11] Gait-speed [0.23]
Gao et al. [26] (2023)	≥65 years Male: 16 Female: 11	Diagnosed with unilateral or bilateral KOA based on the ACR clinical criteria; grade≥ 2 based on the K-L classification; normal or corrected-to-normal vision; ability to step over obstacles without assistance	PNF stretching (n=13) Stretching method: diagonal and spiral patterns and stretching techniques (contract-relax, hold-relax, reversal of antagonists and repeated stretch)	No intervention (health lecture) (n=14)	Pain (VAS) [0.26] Step length [0] Crossing velocity [0.32] Foot clearance [0]
Song et al. [36] (2020)	≥65 years Male: 11 Female: 18	Diagnosed with medial KOA in one or both legs	PNF stretching (n=13) Stretching method: flexion-abduction-internal, extension-adduction-external, flexion-adduction-external and extension-abduction-internal rotations	No intervention (n=16)	Pain (WOMAC) [0.83] Hip extension ROM [0.51] Hip flexion ROM [0.73] Knee flexion ROM [0.63] Ankle plantar flexion ROM [0.53] Ankle dorsal flexion ROM [0.41]
Kannas et al. [34] (2023)	≥50 years	Diagnosed with KOA based on the K-L radiographic evaluation criteria	Passive stretching (n=10) Stretching method: passive stretching in an extended prone position, lumbar L2-L4, maintaining lordosis, immobilizing pelvis for full joint flexion	No intervention (n=10)	Knee ROM [0.43] Mean torque [−0.36] Maximum torque [0.58] Max torque angle [0.62*]
Ahmed [37] (2010)	45 to 70 years	Diagnosed with severe KOA scheduled to have primary total knee arthroplasty	Self-stretching (n=10) Stretching method: seated quadriceps stretching (knee flexion assisted by hand, or by the opposite leg while the patient in a prone position); supine hamstring stretching (fully extended knee and lifted foot with a towel around the foot, in a supine position)	No intervention (n=10)	Pain (VAS) [0.98] ROM [0.47] Pain (WOMAC) [0.82] Stiffness (WOMAC) [0.74] Physical function (WOMAC) [0.66] Total WOMAC [0.72]
II. Stretching exercise and another type of exercise vs. another type of exercise
Weng et al. [38] (2009)	46 to 78 years Male: 26 Female: 106	Diagnosed with moderate KOA based on the Altman grade II	Static stretching and isokinetic exercises (n=33) Stretching method: active-assistive stretching on the quadriceps and biceps femoris in a supine position	Isokinetic exercises (n=33); no intervention control (n=33)	Pain (VAS) [0.60]^† ROM [0.31]^† Lequesne’s index [0.74*]^†
Weng et al. [38] (2009)	46 to 78 years Male: 26 Female: 106	Diagnosed with moderate KOA based on the Altman grade II	PNF stretching and isokinetic exercises (n=33) Stretching method: stretching on the quadriceps and biceps femoris; hold-relax, contract-relax, contract-relax agonist contract and hold-relax agonist contract	Isokinetic exercises (n=33); no intervention control (n=33)	Pain (VAS) [0.73]^† ROM [0.61]^† Lequesne index [0.79*]^†
Author (year)	Participants (age，sex)	Inclusion criteria of participants	Intervention	Outcome variables (ES of relevant outcomes)
Experimental group (n)	Control group (n)
III. Stretching exercise vs. another type of exercise or therapy
Zhang et al. [27] (2022)	45 to 65 years Male: 13 Female: 37	Diagnosed with KOA based on the criteria in the “Guidelines for the Diagnosis and Treatment of Osteoarthritis 2018 Edition.” grade 1 or 2 based on the K-L classification; body mass index ≤36 kg/m²; knee pain with VAS≥2 (0-10 points)	Stretching training exercise (n=25) Stretching method: 5 items of quadriceps training and neuromuscular training	YiJinJing (Qigong) exercise (n=25); 5 items compiled by the State Sports General Administration of China	Pain (VAS) [0.23] Pain (WOMAC) [−0.21] Stiffness (WOMAC) [−0.33] Physical function (WOMAC) [0.11] Mental component summary [−0.59] Physical component summary [0.55] Beck depression inventory [0.79] Perceived stress scale [0.93] Berg balance scale [−0.18] Stride velocity [−0.54] Stride length [0] Stance phase time [0.07] Swing phase time [0.15*]
Nafees et al. [23] (2023)	≥40 years Male: 11 Female: 37	Diagnosed with KOA based on the ACR clinical and radiological criteria	PNF stretching and isometric quadriceps strengthening exercises (n=25) Stretching method: hold-relax on tight hamstring muscle in a supine lying position	Dynamic soft tissue mobilization technique and isometric quadriceps strengthening exercises (n=25)	Pain (VAS) [0] Right AKET [0.12] Light AKET [0.15] Symptoms (KOOS) [−0.06] Pain (KOOS) [0.19] ADLs (KOOS) [0.15] Sports and recreational (KOOS) [0.11] Quality of life (KOOS) [0.02]
Masekar et al. [29] (2020)	40 to 60 years Male: 10 Female:26	Radiologically and clinically diagnosed with KOA by certified orthopedic surgeons or physiotherapists; grade 2 or 3 based on the K-L classification	PNF stretching and other physical therapies (n= 18) Stretching method: in a supine position with hip flexed, hamstring stretch with knee extension performed by a therapist	Muscle energy technique and other physical therapies (n=18)	Pain (NPRS) [0.97] Function (WOMAC total) [0.88] AKET [0.35*]
IV. Stretching exercise as part of various exercises vs. no exercise or another type of exercise/therapy
Suzuki et al. [31] (2018)	50 to 70 years Male: 23 Female: 29	Pre-radiographic KOA (grade 0 or 1 based on the K-L classification); ability to walk independently on a flat surface without an ambulatory assistive device Bilateral KOA cases were not considered separately from unilateral cases	10 programs of multiple exercises including hamstring and quadricep stretching (n=28) Stretching method: hamstring stretching in a chair-sitting position with one knee extended, followed by the upper body tilting forwarded; quadriceps stretching in a side-lying position with knees flexed, followed by pulling one foot behind the body Other exercises: multiple exercises involving training the knee and hip muscles	Single program of quadriceps exercises (n=24)	Pain (VAS) [0.15] Pain and stiffness (JKOM) [0.14] ADLs (JKOM) [0.08] Participation in social activities (JKOM) [0.16] General health (JKOM) [−0.23] Total (JKOM) [0.15] Strength of knee extension [0.05]
Author (year)	Participants (age，sex)	Inclusion criteria of participants	Intervention	Outcome variables (ES of relevant outcomes)
Experimental group (n)	Control group (n)
Mazloum et al. [22] (2018)	≥40 years Male:28 Female:13	Diagnosed with KOA based on the ACR clinical and radiological criteria; knee pain on most days of the previous month (mean 4); osteophyte in radiography	Conventional therapeutic exercise including isometric strengthening and stretching (n=14) Stretching method: in a supine position, knee flexion to straighten the soles, followed by lifting non-healthy limb with full knee extension, using a Thera-band on foot for ankle dorsiflexion	No intervention (n=13) Pilates training exercise (n=14)	Compared to no intervention controlLequesne index [0.35] The time required to complete four functional activities [0.72] Joint position sense [0.86] Compared to Pilates training controlLequesne index [−0.18] The time required to complete four functional activities [0.09] Joint position sense [−0.29]
Assar et al. [35] (2020)	≥40 years All females	Diagnosed with KOA based on the ACR clinical criteria; ≥grade 2 based on the K-L classification; self-reporting knee instability	Water based strengthening and aerobic exercises, step and proprioceptive exercises and core training; static stretching as warm up and cool down (n=12) Warming up stretching exercise included quadriceps, hamstrings, triceps surae, abductors and adductors of hip and gluteal muscles	No intervention (n=12) Total resistance exercise (n=12)	Compared to no intervention control Knee instability [0.78] Stiffness (WOMAC) [0.55] Pain (VAS) [0.57] Berg Balance Scale [0.78] Quadriceps strength [0.47] Knee flexion ROM [0.88] Compared to total resistance exercise control Knee instability [−0.39] Stiffness (WOMAC) [0.03] Pain (VAS) [0.08] Berg Balance Scale [0.33*] Quadriceps strength [−0.07] Knee flexion ROM [−0.48]
Nahayatbin et al. [28] (2018)	45 to 65 years	Diagnosed with KOA, grade 2 or 3 based on the K-L classification 3; ≥grade 3 of lower limb muscles strength based on the Oxford scale	Closed kinetic chain exercise with routine physical therapy; static stretching exercise was included as warm-up (n=16)	Tai Chi exercise with routine physical therapy (n=16) Routine physical therapy (n=16)	Compared to Tai Chi exercise with routine physical therapy control Symptoms (KOOS) [−0.5] Pain (KOOS) [−0.41] ADLs (KOOS) [−0.38] Sport (KOOS) [−0.31] Quality of life (KOOS) [0.04] Total score (KOOS) [−0.49] 6MWT [−0.19] Compared to routine physical therapy control Symptoms (KOOS) [0.64] Pain (KOOS) [0.51] ADLs (KOOS) [0.26] Sport (KOOS) [0.40] Quality of life (KOOS) [0.57] Total score (KOOS) [0.60] 6MWT [0.16*]
Author (year)	Participants (age，sex)	Inclusion criteria of participants	Intervention	Outcome variables (ES of relevant outcomes)
Experimental group (n)	Control group (n)
Arslan and Kul [30] (2022)	40 to 70 years Male: 6 Female: 45	Diagnosed with primary KOA based on the ACR’s clinical and radiologic criteria; grade 2 or 3 based on the K-L classification	Transcutaneous electrical nerve stimulation combined with therapeutic home exercise program including knee stretching (n=25)	Radial extracorporeal shockwave treatment combined with therapeutic home exercise program including knee stretching (n=26)	Pain (VAS) [0.20] Pain (WOMAC) [0.23] Stiffness (WOMAC) [0.19] Physical function (WOMAC) [0.05] Total (WOMAC) [−0.03] Right knee Flexion-active [0.04] Right knee flexion-passive [0] Left knee flexion-active [0.04] Left knee flexion-passive [−0.06] TUG [0.12*]
Lai et al. [24] (2018)	50 to 70 years Male: 2 Female: 32	Diagnosed with KOA by an orthopedic surgeon based on the ACR clinical and radiologic criteria	Strength exercise including squat training and stretching (n=18) Stretching exercise was included as warm-up and cool-down covered the joint motion and muscle stretch.	No intervention (n=16)	Plantarflexion of ankle [0.003] Dorsiflexion of ankle [0.002] Varus of ankle [0.017] Valgus of ankle [0.004] Flexion of knee [0.124*] Extension of knee [0.004]
Ha et al. [39] (2018)	Middle-aged All females	Diagnosed with KOA; received a doctor's consent to participate in the exercise program; did not participate in regular exercise or other exercise programs for the past 6 months	Aquatic exercise (n=9) including stretching exercise as warm up	No intervention (n=8)	Weight [0.12] Body mass index [0.007] Body fat [0.012] Waist circumference [0.13] Systolic blood pressure [0.16] Diastolic blood pressure [0] Fasting blood glucose [0.27] Hemoglobin A₁C [0.27] Triglyceride [0.06] High density lipoprotein cholesterol [0.05] C-reactive protein [0] VO₂ _max [0.34] Right knee flexion peak torque/body weight [0.32] Left knee flexion peak torque/body weight [0.27] Right knee flexion peak torque/body weight [0.12] Left knee flexion peak torque/body weight [0.12] Pain (WOMAC) [0.27] Stiffness (WOMAC) [0.37] Physical function (WOMAC) [0.18] Total (WOMAC) [0.23]
Author (year)	Participants (age，sex)	Inclusion criteria of participants	Intervention	Outcome variables (ES of relevant outcomes)
Experimental group (n)	Control group (n)
da Silva et al. [25] (2015)	≥18 years or above Male: 4 Female: 26	Diagnosed with chronic KOA based on the ACR clinical criteria; moderate to very severe knee pain according to the Lequesne algofunctional index; knee pain on most days at least 3 months within a year	Group rehabilitation program including strengthening, function task-oriented and balance exercise (n=15); stretching exercise was included as warm up Stretching method: active stretching of quadriceps, hamstrings, and calf	No intervention (n=15)	Pain (Lequesne index) [0.41] Distance (Lequesne index) [0.41] Function (Lequesne index) [0.10] Total score (Lequesne index) [0.34] Physical functioning (SF-36) [0.38] Physical role (SF-36) [0.64] Pain (SF-36) [0.39] General health (SF-36) [0.35] Vitality (SF-36) [0.40] Social function (SF-36) [0.03] Emotional role (SF-36) [0.50] Mental health (SF-36) [0.33] Chairstand test [0.43] SitandReach test [0.28] TUG [0.6] 6MWT [0.38]
Oliveira et al. [32] (2012)	50 to 75 years Male: 6 Female: 92	Diagnosed with KOA based on the ACR criteria; ≥grade 2 of the K-L classification	Femoral quadriceps strengthening exercise including stretching as warm up (n=50) Stretching method: hamstring muscles stretching with an elastic band in a seated position	No intervention (n=50)	TUG [0.32] Lequesne Index [0.21] Pain (WOMAC) [0.09] Stiffness (WOMAC) [0.27] Function (WOMAC) [0.18*]
Braghin et al. [33] (2018)	45 to 75 years Male: 11 Female: 31	Diagnosed with KOA based on the K-L classification grade 1 to 3	Symptomatic KOA (n=15); asymptomatic KOA (n=11)	No intervention (n=16)	Symptomatic vs. control Total (WOMAC) [0.26] Pain (WOMAC) [0.34] Stiffness (WOMAC) [0.22] Function (WOMAC) 0.21] Step up/over: Liftup index, left [0.20] Liftup index, right [0.12] Movement time, left [0.21] Movement time, right [0.21] Impact index, left [0.01] Impact index, right [0.18] Semistatic balance: Eyesopen stable surface [0.27] Eyesclosed stable surface [0.15] Eyesopen unstable surface [0.12] Eyesclosed unstable surface: [0.25]
Author (year)	Participants (age，sex)	Inclusion criteria of participants	Intervention	Outcome variables (ES of relevant outcomes)
Experimental group (n)	Control group (n)
			Physical exercises of strengthening, aerobic exercise and functional training including stretching as warm up	Asymptomatic vs. control Total (WOMAC) [0.39] Pain (WOMAC) [0.52] Stiffness (WOMAC) [0.22] Function (WOMAC) [0.35] Step up/over: Liftup index left [0.36] Liftup index right [0.27] Movement time–left [0.21] Movement time–right [0.29] Impact index left [0.17] Impact index right [0.09] Semistatic balance: Eyes-open stable surface [0.28] Eyes-closed stable surface [0.03] Eyes-open unstable surface [0.06] Eyes-closed unstable surface [0.12]

*Favoring experimental group, ^†compared to isometric strengthening group. ES, effect size; KOA, knee osteoarthritis; ACR, American college of rheumatology; VAS, visual analogue scale; K-L, Kellgren and Lawrence; JKOM, Japanese Knee Osteoarthritis Measure; PNF, proprioceptive neuromuscular facilitation; ROM, range of motion; WOMAC, Western Ontario and McMaster Universities Arthritis Index; AKET, active knee extension test; KOOS, Knee Injury and Osteoarthritis Outcome Score; ADL, activities of daily living; NPRS, Numeric Pain Rating Scale; SF-36, 36-Item Short Form Survey; TUG, Timed Up and Go Test; 6MWT, 6-Minute Walk Test.

Korean J Geriatr Gerontol 2024;25:105-121 https://doi.org/10.15656/kjgg.2024.25.2.105