Effects of a Six-Week Eccentric Exercise Program on Patients with Patellar Tendinopathy: Single-Subject Research Study

Abstract

Purpose: Eccentric exercise is commonly recommended in the conservative treatment of chronic tendinopathies. This single-subject research study evaluated the effects of a six-week eccentric exercise program developed for patients with patellar tendinopathy (jumper's knee). Methods: Four patients (mean age 23.75 years; three female, one male) with unilateral patellar tendinopathy participated in this study. A nonconcurrent multiple baseline design was implemented and involved repeated measures of knee pain, knee function, and peak isometric force of the quadriceps and hamstring muscles. Measurements of isokinetic average torque of the quadriceps and hamstring muscles were collected prebaseline and postintervention. The intervention phase involved a six-week eccentric exercise program. Data were analyzed both visually and statistically. Results: Visual results indicated reductions in intensity (n = 3) and unpleasantness (n = 3) of knee pain, improved knee function (n = 3), increased isometric quadriceps peak force of the ipsilateral side (n = 3) and the contralateral side (n = 4), increased isometric hamstring peak force of the ipsilateral side (n = 1) and the contralateral side (n = 1), and increased concentric average torque of the ipsilateral quadriceps (n = 2) and the contralateral side (n = 3). Most visual analyses were supported by the C-statistic. Discussion: The eccentric exercise program showed mixed clinical benefits for four patients with patellar tendinopathy. However, none of the patients achieved full recovery within the suggested six-week treatment period.