Eccentric and Concentric Exercise of the Triceps Surae: An in Vivo Study of Dynamic Muscle and Tendon Biomechanical Parameters

Abstract

Triceps surae eccentric exercise is more effective than concentric exercise for treating Achilles tendinopathy, however the mechanisms underpinning these effects are unclear. This study compared the biomechanical characteristics of eccentric and concentric exercises to identify differences in the tendon load response. Eleven healthy volunteers performed eccentric and concentric exercises on a force plate, with ultrasonography, motion tracking, and EMG applied to measure Achilles tendon force, lower limb movement, and leg muscle activation. Tendon length was ultrasonographically tracked and quantified using a novel algorithm. The Fourier transform of the ground reaction force was also calculated to investigate for tremor, or perturbations. Tendon stiffness and extension did not vary between exercise types (P = .43). However, tendon perturbations were significantly higher during eccentric than concentric exercises (25%-40% higher, P = .02). Furthermore, perturbations during eccentric exercises were found to be negatively correlated with the tendon stiffness (R2 = .59). The particular efficacy of eccentric exercise does not appear to result from variation in tendon stiffness or extension within a given session. However, varied perturbation magnitude may have a role in mediating the observed clinical effects. This property is subject-specific, with the source and clinical time-course of such perturbations requiring further research.

The impact of loading, unloading, ageing and injury on the human tendon

“…; Chaudhry et al . ). The cellular response to concentric or eccentric contractions to the same force level is similar with respect to the expression of collagen (Garma et al .…”

Using technology to measure daily and weekly movement patterns in exercise medicine patients

“…An Achilles tendon, for example, may not necessarily distinguish the difference7 between doing 3 sets of 10 eccentric drops under the watchful eye of a physiotherapist or walking up 30 stairs. What matters more is possibly the amount of daily load that the tendon can ‘just’ cope with at any given point of time.…”

An in vitro investigation into the effects of 10 Hz cyclic loading on tenocyte metabolism

“…However, systematic review articles have generally supported the use of extracorporeal shock wave therapy (ESWT) or eccentric loading as two of the more effective treatment options . Recent studies have focused on establishing mechanisms of action for both ESWT and eccentric loading . ESWT directly applies mechanical stimulation to tendon in the range of 8‐10 Hz, whilst biomechanical studies of eccentric exercises have demonstrated that vibrations occur in the lower limb in a similar 8‐12 Hz range whilst completing the exercises.…”

“…[6][7][8][9][10][11][12] Recent studies have focused on establishing mechanisms of action for both ESWT and eccentric loading. 13,14 ESWT directly applies mechanical stimulation to tendon in the range of 8-10 Hz, whilst biomechanical studies of eccentric exercises have demonstrated that vibrations occur in the lower limb in a similar [8][9][10][11][12] Hz range whilst completing the exercises. With both treatments producing perturbations within the muscle-tendon complex at a frequency of approximately [8][9][10][11][12] Hz, [13][14][15] it has subsequently been hypothesized that [8][9][10][11][12] Hz perturbation may stimulate tendon repair at a cellular level.…”