Increased patellar tendon microcirculation and reduction of tendon stiffness following knee extension eccentric exercises.
METHODS
Controlled laboratory study.


OBJECTIVE
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).


CONCLUSIONS
We conclude that there was increased patellar tendon microcirculation after performing knee extension eccentric exercises that resulted in a reduction in tendon stiffness.
School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University; Center of Physical Therapy, National Taiwan University Hospital, Taiwan, Republic of China.
Nai-Hao
NH
Yin
Wen-Shiang
WS
Chen
Ying-Tai
YT
Wu
Tiffany Tingfang
TT
Shih
Christer
C
Rolf
Hsing-Kuo
HK
Wang
D000328:Adult; D001810:Blood Volume; D015444:Exercise / Q000502:physiology*; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D008833:Microcirculation; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D017847:Patellar Ligament / Q000098:blood supply* / Q000502:physiology*; D013715:Tennis / Q000502:physiology; D055815:Young Adult
D006454:Hemoglobins; D010100:Oxygen