Influence of aging on the in vivo properties of human patellar tendon

• Published in: Journal of applied physiology (1985) Vol. 105; no. 6; pp. 1907 - 1915
• Main Authors: Carroll, C. C, Dickinson, J. M, Haus, J. M, Lee, G. A, Hollon, C. J, Aagaard, P, Magnusson, S. P, Trappe, T. A
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01-12-2008; American Physiological Society
• Subjects: Adult; Aged; Aging; Aging - physiology; Biological and medical sciences; Biomechanical Phenomena; Body Mass Index; Comparative analysis; Female; Fundamental and applied biological sciences. Psychology; Gender differences; Humans; Magnetic Resonance Imaging; Male; Mechanical properties; NMR; Nuclear magnetic resonance; Patellar Ligament - diagnostic imaging; Patellar Ligament - growth & development; Patellar Ligament - physiology; Sex Characteristics; Stress, Mechanical; Tendons; Ultrasonography; Human; In vivo; Vertebrata; Senescence; Mammalia; ultrasonography; Ageing; stress-strain relationship; tendon injury; Lesion; Stress; Tendon
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00059.2008

1 Human Performance Laboratory, Ball State University, Muncie, Indiana; 2 Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense; and 3 University of Copenhagen, Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, Copenhagen, Denmark
Submitted 19 January 2008
; accepted in final form 1 October 2008
Tendons are important for optimal muscle force transfer to bone and play a key role in functional ability. Changes in tendon properties with aging could contribute to declines in physical function commonly associated with aging. We investigated the in vivo mechanical properties of the patellar tendon in 37 men and women [11 young (27 ± 1 yr) and 26 old (65 ± 1 yr)] using ultrasonography and magnetic resonance imaging (MRI). Patella displacement relative to the tibia was monitored with ultrasonography during ramped isometric contractions of the knee extensors, and MRI was used to determine tendon cross-sectional area (CSA) and signal intensity. At peak force, patellar tendon deformation, stress, and strain were 13 ( P = 0.05), 19, and 12% less in old compared with young ( P < 0.05). Additionally, deformation, stiffness, stress, CSA, and length were 18, 35, 41, 28, and 11% greater ( P < 0.05), respectively, in men compared with women. After normalization of mechanical properties to a common force, no age differences were apparent; however, stress and strain were 26 and 22% higher, respectively, in women compared with men ( P < 0.05). CSA and signal intensity decreased 12 and 24%, respectively, with aging ( P < 0.05) in the midregion of the tendon. These data suggest that differences in patellar tendon in vivo mechanical properties with aging are more related to force output rather than an age effect. In contrast, the decrease in signal intensity indirectly suggests that the internal milieu of the tendon is altered with aging; however, the physiological and functional consequence of this finding requires further study.
ultrasonography; tendon injury; stress-strain relationship
Address for reprint requests and other correspondence: T. A. Trappe, Human Performance Laboratory, Ball State Univ., Muncie, IN 47306 (e-mail: ttrappe{at}bsu.edu )