The Acute Transverse Strain Response of the Patellar Tendon to Quadriceps Exercise: A Gender Based Comparative Pilot Study.

Introduction: Tendons are highly adaptive to changes in loading forces put on them always from walking, running, jumping and in other sporting activities. There are few studies involving the Patellar tendon (35, 29), reported a studies on the Acute Transverse Strain response of the Patellar Tendon to quadriceps exercises, a response similar to the Achilles and other tendon studies reported. Resistive exercises are therefore shown to significantly alter the sonographic measures of the patellar tendon structure; the strain, entropy and echogenicity. Method: Ten adult males and ten adult females, with no previous ankle or knee pathology, between 22 and 55 years of age, an average age of 38.5 +/- 15 years; height of 1.60 to 1.80 m and weight of 60 to 90 kg, were recruited. A 5- to 10- MHz linear array transducer was used to obtain standardized sagittal sonograms (8), of the patellar tendon immediately before and after 50 repetitions of leg extensions exercise, 20 mm distal to the inferior pole of the patellar. The transverse strain ε, (Hencky strain) was calculated as a percentage ratio of the post- to pre-exercise tendon thickness and the result statistically analysed (35). Result: There was immediate decrease in patellar tendon thickness (P < 0.05), after the quadriceps exercise in both groups. A transverse strain of -13.8% +/- 7.8% occurred in the males and the females had a transverse strain of -9.6% +/- 3.5%. There were echotexture changes; increased tendon echogenicity (P < 0.05), decrease in entropy (P < 0.05) in both groups. The patellar tendon echogenicity was higher for all participants post exercise while the entropy dropped in the post exercise measurement in all participants. There was also a significant difference in the magnitude of transverse strain response (P < 0.05) between males and females; -13.8% for males against -9.6% for females a difference of 30%. Conclusion: This is a pilot study comparing the male and female acute strain response of the patellar tendon to quadriceps exercise and the consistency of the response in females. This strain response is consistent in both males and females but with a lower magnitude of response in females.