The purpose of this study was to analyze the effects of a quadriceps femoris muscle eccentric training program on strength gain in patients with patellar tendinitis. The effect of an eight-week eccentric exercise program on quadriceps femoris muscle work was evaluated in four groups of subjects–two groups of “normal” (healthy) subjects and two groups of patients with patellar tendinitis. All four groups participated in a home muscle stretching exercise program, but only two groups–one group of normal subjects (N-A) and one group of subjects with tendinitis (T-A)–received additional eccentric training on an eccentric isokinetic dynamometer. The eccentric quadriceps femoris muscle work ratio (involved limb/uninvolved limb x 100) was used to quantify strength in the N-A and T-A Groups. Pain ratings were recorded for subjects with tendinitis before and after the eight-week experiment and were correlated with the dependent variable using a Spearman rank-order correlation coefficient. The N-A Group performed significantly better than all subjects with tendinitis (p less than .05). Subjects in the T-A Group, however, showed a trend toward increasing eccentric quadriceps femoris muscle work capacity over the eight-week training period. As pain ratings in the T-A Group increased, work ratios decreased. We concluded that eccentric exercise may be an effective treatment for patellar tendinitis, but that knee pain may limit optimal gains in strength.
Diagnosis: Patellar tendinopathy
Outcome: Strength tested with eccentric contractions on KIN/COM dynamometer and VAS scores both resting and during activity. Normal subjects gained more strength (23%) than tendinitis group also increased strength but it was not statistically significant, noting that while strength did increase, the pain may limit work loads, which thereby hinders strength increases. Though they tested pain levels they did not report how pain changed over the course of the treatment in any group.
When Assessed: 8 weeks
Subjects: 31 subjects, 15 female, 16 male aged 21-45 years. 15 had patellar tendinopathy and 16 were normal controls.
Protocol: Subjects were divided into 4 groups, normal and tendinitis groups with home stretches only and normal and tendinitis groups with the addition of isokinetic eccentric exercises done 3 times per week on KIN/COM dynamometer for 8 weeks progressing from 30 degrees per second to 70 degrees per second. Six sets of 5 reps were done in week one, 8 sets of 5 week 2 and 12 sets of 5 week 3-8.
Other Activity: No mention.
Chad’s Comments: Noted the Curwin and Stanish theory, suggesting that eccentric exercise would better prepare the patient to withstand the higher forces of eccentric contractions during sports or ADLs with the theory it was these contractions that cause the damage to the tendon, they cited the 1973 Komi study on force velocity curves which is not on Medline. Difficult to determine much from this study as the results were not given in very clear format, the protocol was only 8 weeks long and the exercises were done 3 times per week with sets of only 5 repetitions.
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Chad Reilly is a Physical Therapist, obtaining his Master’s in Physical Therapy from Northern Arizona University. He graduated Summa Cum Laude with a B.S. Exercise Science also from NAU. He is a Certified Strength and Conditioning Specialist, and holds a USA Weightlifting Club Coach Certification as well as a NASM Personal Training Certificate. Chad completed his Yoga Teacher Training at Sampoorna Yoga in Goa, India.