Influence of exercise intensity on training-induced tendon mechanical properties changes in older individuals

Abstract

This study compared the effects of low vs. high intensity training on tendon properties in an elderly population. Participants were pair-matched (gender, habitual physical activity, anthropometrics, and baseline knee extension strength) and then randomly assigned to low (LowR, i.e.,~40 % 1RM) or high (High R, i.e.,~80 % 1RM) intensity resistance training programmes for 12 weeks, 3× per week (LowR, n=9, age 74±5 years; HighR, n=8, age 68 ±6 years). Patellar tendon properties (stiffness [K], Young's modulus [YM], cross-sectional area [T CSA ], and tendon length [T L ]) were measured pre and post training using a combination of magnetic resonance imaging (MRI), B-mode ultrasonography, dynamometry, electromyography and ramped isometric knee extensions. With training K showed no significant change in the LowR group while it incremented by 57.7 % in the HighR group (p<0.05). The 51.1 % group difference was significant (p<0.05). These differences were still apparent when the data was normalized for T CSA and T L , i.e., significant increase in YM post-intervention in HighR (p<0.05), but no change in LowR. These findings suggest that when prescribing exercise for a mixed genders elderly population, exercise intensities of ≤40 % 1RM may not be sufficient to affect tendon properties.

The Achilles tendon is mechanosensitive in older adults: adaptations following 14 weeks versus 1.5 years of cyclic strain exercise

“…strength training) have confirmed that tendons preserve their adaptability to mechanical loading even in older age (Grosset et al, 2014;Karamanidis et al, 2014;Maganaris et al, 2004;OnambelePearson and Pearson, 2012;Reeves et al, 2003a,b). One common finding of the limited number of exercise training intervention studies in older participants is a post-intervention increase in tendon stiffness and Young's modulus, in the absence of any changes in tendon dimensions (Grosset et al, 2014;Onambele-Pearson and Pearson, 2012;Reeves et al, 2003a). The lack of changes in tendon CSA may have been caused by the limited number of transversal scans (typically from 3 regions) taken along the tendon, which may exclude regional CSA changes as reported in studies with younger adults in response to strength training (Arampatzis et al, 2007a;Kongsgaard et al, 2007;Magnusson and Kjaer, 2003;Seynnes et al, 2009).…”

“…The specific motor skill training programme was based on the previous work of Perez et al (2004) and Jensen et al (2005), and was intended to provoke increased excitability of the cortical representation of specific muscles. The motor skill training was conducted bilaterally with a low intensity (30-45% MVC), which could therefore not influence the tendon mechanical, morphological and material properties due to the low tendon strain magnitude (Arampatzis et al, 2007a;Grosset et al, 2014). At the start of each training session, following a standardized warm-up of 2-3 min of submaximal isometric contractions, the participants performed unilateral and bilateral plantarflexion MVCs from which their maximal resultant ankle plantarflexion moments and the 90% intensities for the training session were calculated.…”

“…Furthermore, it appears that in the elderly, adaptations in AT properties in response to loading are adjusted in a way that the maximal strain of the tendinous structures is kept relatively constant, as seen in younger adults (Arampatzis et al, 2007a). However, unlike in muscles, it has to be ensured that the exercise intervention implements tendon strains corresponding to high mechanical loading (intensities of at least 80-90% of MVC) to induce tendon adaptation (Arampatzis et al, 2007a;Grosset et al, 2014). Similar to adaptations to loading, a relatively fast deterioration in the tendon mechanical, material and morphological properties has been shown during bed rest and paralysis (Kubo et al, 2000;Maganaris et al, 2006;Reeves et al, 2005), as well as trainingdetraining studies (Kubo et al, 2012).…”

“…Nonetheless, several exercise intervention studies (e.g. strength training) have confirmed that tendons preserve their adaptability to mechanical loading even in older age (Grosset et al, 2014;Karamanidis et al, 2014;Maganaris et al, 2004;OnambelePearson and Pearson, 2012;Reeves et al, 2003a,b). One common finding of the limited number of exercise training intervention studies in older participants is a post-intervention increase in tendon stiffness and Young's modulus, in the absence of any changes in tendon dimensions (Grosset et al, 2014;Onambele-Pearson and Pearson, 2012;Reeves et al, 2003a).…”

Análises proteômicas do tendão calcâneo sob efeito do envelhecimento e treinamento de força

“…Esses aspectos podem contribuir para melhorar as propriedades mecânicas alteradas com o envelhecimento, diminuindo as falhas em atividades motoras e, consequentemente, o número de lesões (Viidik, 1967;Vogel, 1980;Woo et al, 1981; Haut e Haut, 1997;Maganaris et al, 2004; Burgess et al, 2007;Grosset et al, 2014).…”