Triceps Surae Muscle-Tendon Properties as Determinants of the Metabolic Cost in Trained Long-Distance Runners

Abstract

Purpose: This study aimed to determine whether triceps surae’s muscle architecture and Achilles tendon parameters are related to running metabolic cost (C) in trained long-distance runners.Methods: Seventeen trained male recreational long-distance runners (mean age = 34 years) participated in this study. C was measured during submaximal steady-state running (5 min) at 12 and 16 km h–1 on a treadmill. Ultrasound was used to determine the gastrocnemius medialis (GM), gastrocnemius lateralis (GL), and soleus (SO) muscle architecture, including fascicle length (FL) and pennation angle (PA), and the Achilles tendon cross-sectional area (CSA), resting length and elongation as a function of plantar flexion torque during maximal voluntary plantar flexion. Achilles tendon mechanical (force, elongation, and stiffness) and material (stress, strain, and Young’s modulus) properties were determined. Stepwise multiple linear regressions were used to determine the relationship between independent variables (tendon resting length, CSA, force, elongation, stiffness, stress, strain, Young’s modulus, and FL and PA of triceps surae muscles) and C (J kg–1m–1) at 12 and 16 km h–1.Results: SO PA and Achilles tendon CSA were negatively associated with C (r2 = 0.69; p < 0.001) at 12 km h–1, whereas SO PA was negatively and Achilles tendon stress was positively associated with C (r2 = 0.63; p = 0.001) at 16 km h–1, respectively. Our results presented a small power, and the multiple linear regression’s cause-effect relation was limited due to the low sample size.Conclusion: For a given muscle length, greater SO PA, probably related to short muscle fibers and to a large physiological cross-sectional area, may be beneficial to C. Larger Achilles tendon CSA may determine a better force distribution per tendon area, thereby reducing tendon stress and C at submaximal speeds (12 and 16 km h–1). Furthermore, Achilles tendon morphological and mechanical properties (CSA, stress, and Young’s modulus) and triceps surae muscle architecture (GM PA, GM FL, SO PA, and SO FL) presented large correlations with C.

Active Heat Acclimation Does Not Alter Muscle–Tendon Unit Properties

“…These findings suggest that changes in tissue stiffness induced by acute heat exposure are transient and do not translate into chronic adaptations after repeated active HA sessions. Unaffected muscle and tendon stiffness suggest no effect on the metabolic cost, at least linked to soft tissue stiffness (48), reinforcing the nonalteration of muscle–tendon unit interactions and their absence of negative effect on performance after active HA.…”

Attaching artificial Achilles and tibialis cranialis tendons to bone using suture anchors in a rabbit model: assessment of outcomes

“…For one, the Achilles tendon is expected to experience greater biomechanical loads than the tibialis cranialis tendon. The triceps surae-Achilles tendon unit provides body weight support against gravity and propels the body during locomotion (Machado et al, 2021); conversely, the tibialis cranialis muscle-tendon unit contributes to foot motion during the swing phase of locomotion (Viidik, 1969). In vivo motion of the artificial tendon and suture relative to the anchor, which could affect wear of the suture against the anchor eyelet, could have been greater for the Achilles tendon than for the tibialis cranialis tendon.…”

Effects of gait retraining using minimalist shoes on the medial gastrocnemius muscle‐tendon unit behavior and dynamics during running

“…Repetitive submaximal voluntary contractions of triceps surae account for 25% to 40% of the whole‐body energy expenditure during long‐distance running 4,5 . The MTU behavior (including length, contraction/lengthening length, and velocity) and dynamics (force and power) are considered determinant factors of force production, muscle metabolic cost, and running economy in long‐distance runners 6,7 . Swinnen et al 8 .…”

“…4,5 The MTU behavior (including length, contraction/lengthening length, and velocity) and dynamics (force and power) are considered determinant factors of force production, muscle metabolic cost, and running economy in long-distance runners. 6,7 Swinnen et al 8 preliminarily showed that the medial gastrocnemius (MG) fascicle contraction length and velocity were lower during the running stance phase in habitual non-RFS runners than in RFS runners. Our previous studies reported the MG in habitual non-RFS runners seemed to contract with greater force in relatively isometric behavior and at a slower shortening velocity than RFS during running.…”