Impact of sex and chronic resistance training on human patellar tendon dry mass, collagen content, and collagen cross-linking

Abstract

LeMoine JK, Lee JD, Trappe TA. Impact of sex and chronic resistance training on human patellar tendon dry mass, collagen content, and collagen cross-linking. Am J Physiol Regul Integr Comp Physiol 296: R119 -R124, 2009. First published October 22, 2008 doi:10.1152/ajpregu.90607.2008.-Collagen content and cross-linking are believed to be major determinants of tendon structural integrity and function. Sex and chronic resistance training have been shown to alter tendon function and may also alter the key structural features of tendon. Patellar tendon biopsies were taken from untrained men [n ϭ 8, 1 repetition maximum (RM) ϭ 53 Ϯ 3 kg], untrained women (n ϭ 8, 1 RM ϭ 29 Ϯ 2 kg), and resistance-trained (10 Ϯ 1 yr of training) men (n ϭ 8, 1 RM ϭ 71 Ϯ 6 kg). Biopsies were analyzed for dry mass, collagen content, and collagen cross-linking (hydroxylysylpyridinoline). We hypothesized that these elements of tendon structure would be lower in women than men, whereas chronic resistance training would increase these parameters in men. Tendon dry mass was significantly lower in women than men (343 Ϯ 5 vs. 376 Ϯ 8 g dry mass/mg tendon wet wt, P Ͻ 0.01) and was not influenced by chronic resistance training (P Ͼ 0.05). The lower tendon dry mass in women tended to reduce (P ϭ 0.08) collagen content per tendon wet weight. Collagen content of the tendon dry mass was not influenced by sex or resistance training (P Ͼ 0.05). Similarly, cross-linking of collagen was unaltered (P Ͼ 0.05) by sex or training. Although sex alters the water content of patellar tendon tissue, any changes in tendon function with sex or chronic resistance training in men do not appear to be explained by alterations in collagen content or cross-linking of collagen within the dry mass component of the tendon. human tendon; water content; hydroxyproline; hydroxylysylpyridinoline TENDONS ARE THE FIBROELASTIC structures that connect muscle to bone and convey muscular force (5,22,23). The tensile strength of tendon tissue is estimated to be 50 -100 N/mm 2 (5), a key feature as tendons are subjected daily to high forces. The composition of tendon tissue influences its strength and integrity, playing a key role in force transmission through the muscle-tendon complex (23). Animal and human cadaver studies indicate that tendon tissue is ϳ55-70% water (5, 23), with the remaining dry mass containing the extracellular matrix and tendon cells (5,22). Collagen is the main protein component of tendon tissue, comprising ϳ65-75% of the dry mass (5,22,23). Collagen molecules are joined into fibrils and fibers by lysine-based cross-links [hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP)] (7,22,23,30). Tendon dry mass, collagen content, and cross-links have been shown to impact tendon strength and mechanical properties (22,23,30,52).Tendon tissue is dynamic, highly metabolic, and quite responsive to exercise (23,24,29,34). Tendons should therefore adapt in a positive manner to long-term loading, becoming more damage resistant and ensuring optimal muscular force transmissi...

The magnitude and character of resistance-training-induced increase in tendon stiffness at old age is gender specific

“…In vitro work also supports the suggestion that the tendinous structures of the two genders differ since it is found that female tendon has~9.6% lower dry mass, as well as reduced water content compared with males (LeMoine et al 2009). Interestingly, these authors reported no gender differences in either the cross-linking of collagen, or in collagen content normalised for dry mass (LeMoine et al 2009). What is more, these authors also report no influence of chronic resistance training on these markers (i.e.…”

Real-time sonoelastography of the patellar and quadriceps tendons: pattern description in profesional athletes and healthy volunteers.

“…In addition to contributing to knee function, knowledge about the biomechanical properties of the patellar tendon is important because it is commonly used as autograft material in the reconstruction of ligaments. Tendon strength and mechanical properties are affected by tendon dry mass, collagen content, and cross-linking [13][14][15][16]. Although the impact of exercise training on collagen content and cross-linking in human tendon tissue is unknown, animal data has shown increased collagen content with chronic training and biomechanical studies have revealed that tendon stiffness increases in tendons after long exercise [17,18].…”

Influence of aerobic cycle exercise training on patellar tendon cross‐sectional area in older women

“…This finding is analogous to our previous results after 12 weeks of resistance exercise training in older men and women . Similarly, the patellar tendon collagen content and cross-linking are unchanged in habitually resistance-trained young individuals (Lemoine et al, 2009). However, it is still likely that some change in the internal structure of the tendon occurs with exercise training, as several studies in young and old individuals report changes in the mechanical properties of the tendon (Reeves et al, 2003;Kongsgaard et al, 2007;Couppe et al, 2008;Seynnes et al, 2009;Carroll et al, 2011), albeit sometimes minor.…”