Effect of Neuromuscular Electrical Stimulation During Walking on Pain Sensitivity in Women With Obesity With Knee Pain: A Randomized Controlled Trial.

OBJECTIVE: To assess the extent to which pain sensitivity is altered in women with obesity with frequent knee symptoms who walk with either a hybrid training system (HTS) that provides antagonist muscle electrical stimulation vs sensory transcutaneous electrical nerve stimulation (TENS). DESIGN: Randomized, double-blinded, controlled trial. SETTING: University-based fitness center. PARTICIPANTS: Twenty-eight women (N=28) with obesity, aged 40-70 years, with daily knee symptoms. INTERVENTIONS: Participants were randomized to 12 weeks of biweekly 30-minute walking exercise with either HTS (HTSW group) or sensory TENS (control group). MAIN OUTCOME MEASURES: Pressure pain thresholds (PPTs) at the more symptomatic knee (local PPT) and PPT at the ipsilateral pain-free wrist (remote PPT). RESULTS: After adjustment for preintervention values and body mass index (BMI), there was a statistically significant improvement in local PPT in the HTSW group compared with the control group (P=.039). After adjustment for pretraining value, age, and BMI, changes in remote PPT when comparing groups did not reach statistical significance, although the HTS group tended to demonstrate increased remote PPT (P=.052) compared with the control group. Moreover, after adjustment for pretraining value, knee pain, and quality of life, comparing groups did not reach statistical significance, although the HTS group tended to demonstrate decreased knee pain (P=.069) compared with the control group. CONCLUSIONS: Augmentation of walking exercise with HTS was more effective than application of sensory TENS in improving local pain sensitivity at the knee but not at the wrist in women with obesity with frequent knee symptoms.

The Effect of Neuromuscular Electrical Stimulation During Walking on Muscle Strength and Knee Pain in Obese Women With Knee Pain: A Randomized Controlled Trial.

OBJECTIVE: The aim of the study was to assess the effectiveness of a hybrid training system with walking that simultaneously applies electrical stimulation to the knee extensors/flexors during walking in obese women with knee pain. DESIGN: This is a randomized, single-blind (assessor), controlled trial. Twenty-eight obese women with knee pain were randomized to 12 weeks of biweekly walking with either hybrid training system with walking or with transcutaneous electrical nerve stimulation (control). Primary outcomes (maximum isokinetic knee extensor torque and maximum isokinetic knee flexor torque) and secondary outcomes (20-m walk time, chair-stand time, stair-climb time, knee pain, and knee-related quality life) were evaluated. Change-point regression analyses were used to model the interaction for the primary outcomes. Two-sample t tests were used on pre-post change scores in secondary outcomes. RESULTS: Knee extensor torque increased significantly more in the hybrid training system with walking group than the control group when baseline knee extensor torque was greater than 57.2 Nm (P = 0.0033). When baseline knee flexor torque was at 30 or 50 Nm, there was a trend toward greater increase in the hybrid training system with walking group than the control group (P = 0.0566, P = 0.0737, respectively). There were no significant differences between groups in secondary outcomes. CONCLUSIONS: These results suggest that hybrid training system with walking is effective for improving knee extensor torque in obese women with knee pain. However, the superiority of hybrid training system with walking may vary depending on baseline knee muscle strength.

Evaluation of the Combined Application of Neuromuscular Electrical Stimulation and Volitional Contractions on Thigh Muscle Strength, Knee Pain, and Physical Performance in Women at Risk for Knee Osteoarthritis: A Randomized Controlled Trial.

BACKGROUND: Knee osteoarthritis (OA) is a leading cause of disability that is associated with quadriceps weakness. However, strengthening in people with or with risk factors for knee OA can be poorly tolerated. OBJECTIVE: To assess the efficacy of a 12-week low-load exercise program, using a hybrid training system (HTS) that uses the combination of neuromuscular electrical stimulation and volitional contractions, for improving thigh muscle strength, knee pain relief, and physical performance in women with or with risk factors for knee OA. DESIGN: Randomized, single-blinded, controlled trial. SETTING: Exercise training laboratory. PARTICIPANTS: Forty-two women 44-85 years old with risk factors for knee OA. INTERVENTIONS: Participants randomized to 12 weeks of biweekly low-load resistance training with the HTS or on an isokinetic dynamometer (control). OUTCOMES: Maximum isokinetic knee extensor torque. Secondary measures included maximum isokinetic knee flexor torque, knee pain (Knee Injury and Osteoarthritis Outcome Score), and timed 20-m walk and chair stand tests. RESULTS: The HTS and control treatments resulted in muscle strengthening, decreased knee pain, and improved physical performance. HTS group quadriceps and hamstring strength increased by 0.06 ± 0.04 Nm/kg (P > .05) and 0.05 ± 0.02 Nm/kg (P = .02), respectively. Control group quadriceps and hamstring strength increased by 0.03 ± 0.04 Nm/kg (P > .05) and 0.06 ± 0.02 Nm/kg (P = .009), respectively. Knee pain decreased by 11.9 ± 11.5 points (P < .001) for the HTS group and 14.1 ± 15.4 points (P = .001) for the control group. The 20-m walk time decreased by 1.60 ± 2.04 seconds (P = .005) and 0.95 ± 1.2 seconds (P = .004), and chair stand time decreased by 4.8 ± 10.0 seconds (P > .05) and 1.9 ± 4.7 seconds (P > .05) in the HTS and control groups, respectively. These results did not differ statistically between the HTS and control groups. CONCLUSIONS: These results suggest the HTS is effective for alleviating pain and improving physical performance in women with risk factors for knee OA. However, the HTS does not appear to be superior to low-load resistance training for improving muscle strength, pain relief, or physical function. CLINICAL TRIAL REGISTRATION NUMBER: NCT02802878. LEVEL OF EVIDENCE: I.