YIA Winner: Load Specific Patellar and Achilles Tendon Adaptation.. - Wiesinger

YIA Winner at 21st annual congress of the ECSS - ECSS Vienna 2016 Wiesinger, H.P.1, Rieder, F.1, Kösters, A.1, Müller, E.1, Seynnes, O.R.2 1: PLUS (Salzburg, AUT), 2: NSSS (Oslo, NOR) Introduction Tendon viscoelastic properties enable, inter alia, reducing the metabolic cost of locomotion (Lichtwark et al. 2007), enhancing muscle power production (Alexander & Bennet-Clark 1977) or preventing peak load injuries (Roberts & Azizi 2010). While the dual requirement of being strong but functionally adequate seem to be met by inherent repair and remodelling processes, current knowledge on tendon adaptations is largely fragmented into studies yielding partial information. This study aimed to determine whether distinct sets of tendon properties are seen in athletes engaged in sports with contrasting requirements for tendon function and structural integrity. Methods Thirty-nine male adults (27.3 ± 5.7 yrs) divided in four groups (elite ski jumpers, endurance runners and water polo players, and controls) were tested. From the original data set by combining ultrasonography, dynamometry, electromyography and 2D motion analysis, the following variables are presented: patellar (PT) and Achilles tendon (AT) stiffness, cross-sectional area normalized to body mass (nCSA), hysteresis and recovered strain energy. Results Tendon nCSA was smaller in water polo players than in other athletes (AT and PT; -24 to -28%) or controls (PT only; -9%). In runners (PT only; +26%) and ski jumpers (PT and AT; +21% and +13%, respectively), nCSA was larger than in controls. However, tendon stiffness only differed in ski jumpers, compared to controls (PT and AT; +11% and +27%, respectively) and water polo players (AT only; +23%). Hysteresis values were lower in the PT of ski jumper (-33%) and runner (-30%) compared to controls. The recovered strain energy was greater in ski jumpers compared to water polo players and controls (PT +55% and +52% and AT +32% and +36%, respectively) and to runners (PT only; +40%). Discussion Tendon strength or fatigue quality requirements seem to be preserved by adjustments of tendon size. However, uncoupled morphological and mechanical properties indicate that functional requirements may also influence tendon adaptations. The ability to conserve mechanical energy does not seem particularly confined to individuals subjected to a high volume of running training. Similar group differences in properties of PT and AT suggest that adaptive mechanisms may override their functional specificity. References 1. Alexander R McN & Bennet-Clark H C. Storage of elastic strain energy in muscle and other tissue. Nature, 1977. 2. Lichtwark G A & Wilson A M. Is Achilles tendon compliance optimised for maximum muscle efficiency during locomotion? J Biomech, 2007. 3. Roberts T J & Azizi E. The series-elastic shock absorber: tendons attenuate muscle power during eccentric actions. J Appl Physiol (1985), 2010. Contact: [email protected]