Habitual loading results in tendon hypertrophy and increased stiffness of the human patellar tendon

Abstract

The purpose of this study was to examine patellar tendon (PT) size and mechanical properties in subjects with a side-to-side strength difference of > or =15% due to sport-induced loading. Seven elite fencers and badminton players were included. Cross-sectional area (CSA) of the PT obtained from MRI and ultrasonography-based measurement of tibial and patellar movement together with PT force during isometric contractions were used to estimate mechanical properties of the PT bilaterally. We found that distal tendon and PT, but not mid-tendon, CSA were greater on the lead extremity compared with the nonlead extremity (distal: 139 +/- 11 vs. 116 +/- 7 mm(2); mid-tendon: 85 +/- 5 vs. 77 +/- 3 mm(2); proximal: 106 +/- 7 vs. 83 +/- 4 mm(2); P < 0.05). Distal tendon CSA was greater than proximal and mid-tendon CSA on both the lead and nonlead extremity (P < 0.05). For a given common force, stress was lower on the lead extremity (52.9 +/- 4.8 MPa) compared with the nonlead extremity (66.0 +/- 8.0 MPa; P < 0.05). PT stiffness was also higher in the lead extremity (4,766 +/- 716 N/mm) compared with the nonlead extremity (3,494 +/- 446 N/mm) (P < 0.05), whereas the modulus did not differ (lead 2.27 +/- 0.27 GPa vs. nonlead 2.16 +/- 0.28 GPa) at a common force. These data show that a habitual loading is associated with a significant increase in PT size and mechanical properties.

Life-long endurance running is associated with reduced glycation and mechanical stress in connective tissue

“…The protocol for measuring anatomical cross-sectional area of the quadriceps femoris muscle (Q-CSA) and patellar tendon CSA/length has been described elsewhere (Couppe et al 2008;Mikkelsen et al 2013). In brief, Q-CSA of the mid-thigh level and tendon CSA/ length was measured using magnetic resonance imaging (MRI; General Electric, Sigma Horizon LX 1.5 T, T1-weighted SE, Millwaukee, WI, USA).…”

“…The typical error percentage was 2 %. Patellar tendon CSA and length was determined by T1w TSE para axial and sagital plane MRI using a knee coil and parameters as described previously (Couppe et al 2008). A plastic tube containing 1.0 % CuSO 4 was placed in the FOV for normalization of tendon signal intensity.…”

“…The axial scans were performed perpendicular to the patellar tendon. As described in detail elsewhere, the tendon CSA was measured regionspecific (proximal, mid, and distal; Couppe et al 2008). Average tendon CSA was calculated from the three sites and used for further analysis.…”

“…Tendon biopsies were obtained from the nondominant extremity (Couppe et al 2008) according to procedures described in detail elsewhere ). In brief, after sterilization of the insertion site, the skin was injected with local anesthetic (1 % lidocaine), and a 3-to 5-mm-long incision was made distally to the patella apex.…”

Olimpik Okçularda Parmak Fleksör Tendonlarının Sonografik Değerlendirmesi

“…Overuse type of tendon injuries are among the most common musculoskeletal pathologies in recreational and competitive athletes; and the structural changes have been widely reported (1). Load-induced structural changes, especially hypertrophy, have been also studied in tendons of animals and healthy subjects (2)(3)(4)(5)(6)(7)(8)(9)(10)(11). On the other hand, relevant data regarding asymptomatic athletes are scarce (6,10,12).…”