Gender Differences of Achilles tendon Cross-sectional Area during Loading

Abstract

The Achilles tendon (AT) is larger and stiffer in males compared to females. AT stiffness is determined by length differences during loading. However, as some collagen fibres run transversely, changes in cross-sectional area (CSA) are also expected. The study investigates the gender differences of AT-CSA during maximal voluntary isometric contraction (MVIC). Fifteen males and fifteen females were positioned prone on the isokinetic dynamometer with knee extended and ankle flexed 90°. AT-CSA [mm 2 ] from rest to MVIC during plantar flexion was sonographically assessed. AT-CSA maximal deformation [mm 2 ] was subtracted by CSA MVIC –CSA rest . AT-CSA compliance [mm 2 /Nm] and strain [%] were calculated by dividing the CSA deformation [mm 2 ] by peak torque [Nm] and CSA at rest [mm 2 ], respectively. Gender differences were assessed by an independent sample t-test with Bonferroni correction (α=0.01). AT-CSA dimensions at rest (p=0.001) and contraction (p=0.001) as well peak torque (p=0.001) were statistically significant higher in males (54.4±5.1 mm 2 , 53.7±5.1 mm 2 , 120.1±26.8 Nm) compared to females (46.2±7.0 mm 2 , 43.4±6.9 mm 2 , 86.9±21.6 Nm). AT-CSA deformation (p=0.000) strain (p=0.000) and compliance (p=0.000) were found to be statistically significant higher in females (–2.8±0.9 mm 2 , –6.2±2.0%, –0.033±0.018 mm 2 /Nm) compared to males (–0.8±1.8 mm 2 , –1.4±3.3%, –0.007±0.008 mm 2 /Nm). During loading, the AT also deforms at the transverse level by reducing its CSA. CSA reduction was higher in females, indicating also higher CSA compliance compared to males. Higher CSA compliance might indicate higher adaptability towards loading and might be discussed as a protective factor.

Is There a Relationship between the Morphology of Connective Tissue and Reactivity during a Drop Jump? Influence of Sex and Athletic Performance Level

“…Moreover, sex differences are also present in the connective tissue morphology. Specifically, males demonstrated significantly larger AT-CSA than females [ 16 ]. This finding must be considered cautiously as, in many studies such as the one cited, tendon values were not normalized in relation to body mass, since if the samples are not homogeneous in relation to the body mass, the results after normalizing the tendon values in relation to the body mass might be different [ 3 ].…”

“…Therefore, the aim of this study is twofold: (i) to examine the relationship between the morphology of patellar tendon (PT), AT and plantar fascia (PF), and RSI during a DJ in amateur endurance runners; and (ii) to determine the influence of sex and athletic performance level on the morphology of the aforementioned structures and RSI during a DJ. Taking into account that previous studies [ 15 , 16 ] found that men showed both higher values of RSI and AT-CSA, we hypothesized that greater values of the connective tissue characteristics exhibit a greater RSI, and the variables of sex and athletic performance level influence this relationship. Additionally, given the differences in connective tissue in absolute values mentioned above, we also hypothesized that men would show greater values for normalized tendon thickness and CSA than women.…”

Motor Control and Achilles Tendon Adaptation in Adolescence: Effects of Sport Participation and Maturity

“…One study, found that the patellar tendon CSA increased 27% from mid to late adolescence (16-18 years) ( Mersmann et al, 2017a ), whereas others report reductions in tendon cross sectional areas in early adolescence ( Neugebauer and Hawkins, 2012 ). These controversial reports about the tendon’s hypertrophy in childhood to adulthood could be attributed to the age cohort and the inclusion of adolescents who participated in sports or not ( Mersmann et al, 2017b , Cassel et al, 2017 ), and gender ( Intziegianni et al, 2017 ). Our findings from this longitudinal study show that athletes had greater cross-sectional area and longer resting length of the Achilles tendon than non-athletes.…”

Effect of ankle joint position on triceps surae contractile properties and motor unit discharge rates

“…As such, a study recording MUDRs during contractions at different muscle lengths in multiple muscles from the same individuals, while controlling for the effect of prolonged muscle stretch on the motor neuron pool (Guissard et al, 1988; Trajano et al, 2014), may be necessary to gain a better understanding of how muscle length affects MUDRs. Additionally, sex‐based differences in tendon compliance (Intziegianni et al, 2017) suggest there may be differences in how muscle length is altered with ankle joint position in males and females, thus leading to an altered neural response.…”

“…Ten males (24 ± 3 years old, 81 ± 7 kg, 181 ± 5 cm) volunteered for the study. The homogenous population in this study was chosen to minimize the influence of sex-based differences in Achilles tendon stiffness (Intziegianni et al, 2017), which would affect TS muscle length changes with alterations of ankle joint position. All participants were recreationally active, defined as not involved in any varsity level or systematic training activities, but not sedentary, and were considered healthy and free of neuromuscular disease.…”