Context: Knee injury is a common problem for runners. Knee pain is a common symptom in knee injury and is associated with alterations in knee and hip muscle activation and hip joint angles. Relieving pain through intervention may help to restore neuromuscular function. Objective: To examine the effects of ice and transcutaneous electrical nerve stimulation (TENS) combination treatment on perceived knee pain, hip frontal plane angle, and muscle activation during running in individuals with experimental knee pain (EKP). Design: Crossover. Setting: Laboratory. Subjects: 19 participants (11 males and 8 females, 23.2 ± 1.9 y, 176 ± 11.6 cm, 71.5 ± 16.9 kg; right leg dominant). Interventions: Hypertonic saline was infused into the infrapatellar fat pad for 74 minutes (total 11.1 mL). Subjects underwent 2 treatment conditions (sham; ice/TENS combination). Measurements were recorded during running at 4 time points (preinfusion, postinfusion, posttreatment, and postinterval). Main Outcome Measures: Perceived knee pain on a 100-mm visual analog scale (VAS), knee and hip muscle peak electromyography (EMG) amplitude, and hip adduction angles. Results: Hypertonic saline infusion increased perceived anterior knee pain in all participants. The average of peak perceived knee pain was 28 mm on a 100-mm VAS in EKP application. While the increased perceived knee pain level stayed consistent across time in the sham session, ice/TENS combination treatment significantly reduced perceived knee pain by 35% at 6 minutes after the treatment start (p = 0.049), and the reduced knee pain lasted for 22 minutes (p > 0.05). Peak EMG amplitude of the gluteus medius was decreased by 13.5% and 14.3% (p = 0.023; p = 0.013) during running after EKP in sham and treatment sessions, respectively. However, the peak EMG amplitude was not restored to pain-free level during running after the treatment (p = 0.026). No other muscles changed their peak EMG amplitude due to EKP or treatment. Hip adduction angles during running were also not altered by EKP or treatment (p > 0.3) in both sham and treatment sessions. Conclusions: EKP increased perceived knee pain and decreased peak muscle activation of the gluteus medius during running. Ice/TENS combination treatment reduced perceived knee pain quickly, but did not restore neuromechanics during running.



College and Department

Life Sciences; Exercise Sciences



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ice/TENS combination treatment, peak EMG amplitude, hip adduction angle, hypertonic saline infusion