Increased patellar tendon microcirculation and reduction of tendon stiffness following knee extension eccentric
Nai-Hao Yin1, Wen-Shiang Chen, Ying-Tai Wu
1School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University; Center of Physical Therapy, National Taiwan University Hospital, Taiwan, Republic of China.
Study Design:
Controlled laboratory study.
Objectives:
To measure and compare patellar tendon stiffness and microcirculation in college tennis players and nonathletic students when performing eccentric knee extension exercises that do and do not reduce tendon stiffness.
Background:
Previous studies suggest that tendon microcirculation response during exercises may vary based on the tendon's plastic properties. Methods The study included 3 groups of college-age male students: tennis players who performed 4 sets of either 40 (n = 12) or 80 (n = 13) repetitions of eccentric knee extension exercise and nonathletic students (n = 14) who performed 4 sets of 40 repetitions. Tendon stiffness was measured before and after exercise completion. Changes in total hemoglobin and oxygen saturation (OSat) were analyzed while performing the 4 sets. Comparisons were made within and between the groups. The level of association between tendon microcirculation and stiffness reduction was assessed.
Results:
The 2 groups (player/4 × 80 and student/4 × 40) exhibiting patellar tendon stiffness reductions (P<.008) showed higher total hemoglobin and OSat levels, above the pre-exercise levels, in the fourth set compared to the first set of exercises (P<.004). The tennis players who performed 4 sets of 40 repetitions exhibited higher OSat levels in the fourth set than in the first set (P = .004) but had no reduction in tendon stiffness. Changes in OSat levels in the fourth set were correlated with patellar tendon stiffness reductions (r = -0.381, P = .02).
Conclusion:
We conclude that there was increased patellar tendon microcirculation after performing knee extension eccentric exercises that resulted in a reduction in tendon stiffness.
