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

Abstract

Human tendon mechanical properties are modified with loading. Moreover, there are indications that the training response in the tendon is gender specific. The aim of the current study was to examine whether in vivo patella tendon stiffness (K) differentially alters with training in older males compared with females. We also aimed to identify which endocrine pathway underlies the responses. Maximal knee extensor forces were also monitored to determine the training effect on muscle function. Fourteen healthy, habitually active older persons (seven males aged 74.0 ± 1.2 years (mean±SEM) and seven females aged 76.7 ± 1.2 years) were tested at baseline and after 12 weeks of weekly, progressive resistance training. With training, percentage increase in quadriceps maximum voluntary isometric force (MVC) was similar in males (2,469.6 ± 168.0 to 3,097.3 ± 261.9 N; +25.3 ± 6.1% (p < 0.01)) and females (1,728.8 ± 136.3 to 2,166.5 ± 135.8 N; +30.4 ± 15.1% (p < 0.05)), respectively. K increased more in males (338.0 ± 26.6 to 616.9 ± 58.7 N/mm; 79.8 ± 4.2% (p < 0.001)) compared to females (338.9 ± 31.0 to 373.2 ± 25.8 N/mm; +13.0 ± 3.7% (p < 0.001)). Interestingly, a pattern was found whereby below ~40% MVC, the females showed their greatest degree of K changes, whereas the males showed their greatest degree of K change above this relative force level. This gender contrast was also true at a standardised force level (1,200 N), with 5.8 ± 0.4% vs. 82.5 ± 1.8% increments in the females (i.e. value change from 380.3 ± 14.1 to 402.4 ± 13.3 N/mm) and the males (i.e. value change from 317.8 ± 13.8 to 580.2 ± 30.9 N/mm), respectively (p < 0.001). While circulating levels of both IGF-I and IL-6 did not alter with training, IGFBP-3 showed a significant training effect (19.1 ± 4.8%, p < 0.001) and only in the male sub-group (p = 0.038). We show here that with training, in vivo older females' tendon is less dramatically modulated than that of males'. We also show that the relative forces, at which the greatest adaptations are exhibited, differ by gender, with a suggestion of endocrine adaptations in males only. We thus propose that both training and rehabilitation regimens should consider gender-specific tendon responsiveness, at least in older persons.

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

“…In an elderly population, 14 weeks of high load resistance training (at 80 % 5RM) has been shown to increase the stiffness of the patella tendon by 65 % (Reeves et al 2003a). Similar findings have been reported by others including descriptions on how training modality and/or gender impact on the tendon responses (Onambele et al 2008;Onambele-Pearson and Pearson 2012). In contrast, it has been observed that lower intensity exercise in the form of a 6-month progressive walking programme does not influence tendon properties in older adults (Kubo et al 2008).…”

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

“…5) to stimulate further adaptive changes in the Achilles tendon in older female adults. It should be stated, that post-menopausal elderly women have a diminished tendon modulation to exercise (Onambele- Pearson and Pearson, 2012). However, whether or not the identified stagnation in the muscle and tendon adaptation can be related to a possible sex-specific reduction in the ability to respond to the anabolic stimuli in the musculotendinous tissue (Hansen and Kjaer, 2014) cannot be answered based on the current study design.…”

“…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).…”

Effects of series elastic compliance on muscle force summation and the rate of force rise

“…Similar magnitudes of change in stiffness have been demonstrated for human lower limb tendons in response to resistance training and bed rest. Twelve to 14 weeks of resistance training has been shown to facilitate a 50-84% increase in tendon stiffness and elastic modulus in young Malliaras et al, 2013) and older (Reeves et al, 2003;Onambele-Pearson and Pearson, 2012) adults. Conversely, 21 and 90 days of bed rest may reduce tendon stiffness (and elastic modulus) by 29% (De Boer et al, 2007) and 58% (Reeves et al, 2005), respectively.…”