Muscle-tendon architecture in Kenyans and Japanese : Potential role of genetic endowment in the success of elite Kenyan endurance runners

Aim The specificity of muscle-tendon and foot architecture of elite Kenyan middle- and long-distance runners has been found to contribute to their superior running performance. To investigate the respective influence of genetic endowment and training on these characteristics, we compared leg and foot segmental lengths as well as muscle-tendon architecture of Kenyans and Japanese males (i) from infancy to adulthood and (ii) non-athletes versus elite runners. Methods The 676 participants were divided according to their nationality (Kenyans and Japanese), age (nine different age groups for non-athletes) and performance level in middle- and long-distance races (non-athlete, non-elite and elite …

Muscle-Tendon Interaction During Human Dolphin-Kick Swimming

Without high impact forces, it is not clear how humans can utilize tendon elasticity during low-impact activities. The purpose of the present study was to examine the muscle-tendon behavior together with the electromyographic (EMG) activities of the vastus lateralis (VL) muscle during the human dolphin-kicking. In a swimming pool, each subject (n = 11) swam the 25 m dolphin-kicking at two different speeds (NORMAL and FAST). Surface EMGs were recorded from the VL and biceps femoris (BF) muscles. Simultaneous recordings of the knee joint angle by electro-goniometer and of the VL fascicle length by ultrasonography were used to calculate the muscle-tendon unit and tendinous length of VL(L-MTU a…

Specific muscle-tendon architecture in elite Kenyan distance runners

The Achilles tendon moment arm (MA_AT) and foot lever ratio (FLR) can play important roles for force production and movement economy during locomotion. This notion has become more relevant, and suggestion has been given that the Kenyan runners belonging to the world elite would have specific anatomical, mechanical, and functional properties in their lower limbs and that this feature could be responsible for their high running economy. The present study aimed to characterize the AT of elite Kenyan distance runners as compared with Japanese ones, and to examine the potential relationship with their running performance. Ultrasonography was used to measure AT cross-sectional area and AT soleus …

Muscle-Tendon Interaction During Human Dolphin-Kick Swimming

Without high impact forces, it is not clear how humans can utilize tendon elasticity during low-impact activities. The purpose of the present study was to examine the muscle-tendon behavior together with the electromyographic (EMG) activities of the vastus lateralis (VL) muscle during the human dolphin-kicking. In a swimming pool, each subject (n = 11) swam the 25 m dolphin-kicking at two different speeds (NORMAL and FAST). Surface EMGs were recorded from the VL and biceps femoris (BF) muscles. Simultaneous recordings of the knee joint angle by electro-goniometer and of the VL fascicle length by ultrasonography were used to calculate the muscle-tendon unit and tendinous length of VL (LMTU a…

Age-specific neuromuscular interaction during elderly habitual running

Aim It has been reported that advancing age causes tendons to become more compliant and fascicles length shorter. This could then lead to enhancement of movement efficiency provided that the elderly adults can activate their muscles in the same way as the younger adults (YOUNG) during dynamic movements. This study was designed to examine the age-specific behaviour of the medial gastrocnemius (MG) fascicles and tendinous tissues together with lower-leg muscle activities when the well-trained elderly runners ran on the treadmill at preferred speeds. Methods The well-trained 11 elderly subjects (ELD) who have running experiences and 11 YOUNG were recruited as subjects. While ELD were running o…

Specific distribution of cross-sectional area in each hamstring muscle of sprint runners and relationship between those and sprint performance

Economical running strategy for East African distance runners

The superior success of East-African endurance runners has stimulated a large amount of interest in exploring valid reasons for their performance, especially for neuromuscular mechanics. This review provides a brief overview of classic neuromuscular interaction during running; and, thereafter, describes a specific neuromuscular interaction alternative to the classic stretch-shortening cycle concept for enhancing the running economy of East-African distance runners.