Muscle–tendon interaction and EMG profiles of world class endurance runners during hopping

Abstract

The present study examined the muscle-tendon interaction of ten international level Kenyan runners. Ultrasonography and kinematics were applied together with EMG recordings of lower limb muscles during repetitive hopping performed at maximal level. The ten Kenyans had longer gastro Achilles tendon at rest (p < 0.01) as compared with ten control subjects matched in height. Conversely, the stretching and shortening amplitudes of the tendinous tissues of the medial gastrocnemius (MG) muscle were significantly smaller in the Kenyans than in controls during the contact phase of hopping. This applied also to the fascicle length changes, which were smaller and more homogeneous among Kenyans. These limited musculo-tendinous changes resulted in higher maximal hopping height and in larger power despite their reduced body weight. The associated finding of a greater shortening to stretching ratio of the MG tendinous tissues during contact could imply that the Kenyan MG muscle-tendon unit is optimized to favor efficient storage and recoil of elastic energy, while operating at optimal muscle fascicle working range (plateau region).

Developmental differences in dynamic muscle-tendon behavior: implications for movement efficiency

“…It has been demonstrated both computationally (Ettema, 2001;Lichtwark and Wilson, 2005) and experimentally (Hoffrén et al, 2012;Sano et al, 2013) that tendons with different mechanical properties may require different muscle activation strategies to achieve similar levels of efficiency. Moreover, previous studies have shown lower agonist and higher antagonist muscle activities in pre-pubertal children than in postpubertal children and adults (Lloyd et al, 2012) during the preactivation, braking and propulsive phases of jumping activities.…”

Economical running strategy for East African distance runners

“…1). In addition, the East-Africans showed smaller tendon stretching (strain) and shortening during hopping exercises 13) (Fig. 2) data).…”

Effects of ethnicity on the relationship between vertical jump and maximal power on a cycle ergometer

“…Recently, some authors reported specific anatomical properties such as greater tendon length of the lower limbs in Afro-Caribbean subjects compared to Caucasian subjects (Kunimasa et al, 2014; Sano et al, 2013). Indeed, the greater tendon length may positively contribute to the output from the muscle tendon complex in a stretch shortening cycle during jumping with prestretch and this feature could be responsible for better vertical jump performance in the Afro-Caribbean participants.…”