University of Jyväskylä

Dissertation: 2 September 2016 MSc Lauri Stenroth (Faculty of Sport and Health Sciences, Biomechanics)

Start date: Sep 02, 2016 12:00 PM

End date: Sep 02, 2016 03:00 PM

Location: Seminaarinmäki, Seminarium, S212

Lauri Stenroth. Kuvaaja Elisa Vuori-Stenroth
Lauri Stenroth. Kuvaaja Elisa Vuori-Stenroth
MSc Lauri Stenroth defends his doctoral dissertation in biomechanics “Structure and function of human triceps surae muscle and tendon in aging”. Opponent Professor Bill Baltzopoulos (Liverpool John Moores University, UK) and Custos Professor Taija Juutinen (University of Jyväskylä). The doctoral dissertation is held in English.


Aging is associated with loss of muscle mass leading to impairments in muscle function, such as loss of muscle strength or power. These impairments may eventually lead to physical disabilities. Although loss of muscle mass has a major role in age-related loss of muscle function, there is a disproportionate loss of muscle strength and power with aging suggesting that other factors are also involved. These other factors may include age-related modifications in muscle architecture and tendon mechanical properties, factors that have a significant effect on muscle function. Currently there is no consensus about age-related changes in muscle architecture or tendon mechanical properties, or their role in age-related impairments of physical function. Therefore, the aim of this thesis was to examine associations between aging and muscle architecture, tendon mechanical properties and muscle-tendon function during walking in the human triceps surae muscle by comparing healthy young and older adults. Associations between tests of physical function and triceps surae muscle-tendon properties were also investigated in older adults. The results suggested only modest effects of aging on triceps surae muscle architecture and Achilles tendon mechanical properties. However, inter-individual differences in triceps surae muscle architecture and Achilles tendon stiffness explained variance in 6-minute walk test and in timed “up-and-go” –test in older adults. Muscle-tendon function was found to be dependent on walking speed in older adults, with no significant differences between young and older adults when compared at matched walking speed. These results suggest that the commonly observed age-related slowing of preferred walking speed may represent an attempt to compensate for loss of muscle strength in triceps surae muscle. In conclusion, the results of the current thesis suggest that aging may be related to changes in triceps surae muscle architecture and Achilles tendon mechanical properties. However, these changes seem to be part of an adaptation process that helps to maintain muscle function despite declines in muscle mass and strength with aging.

The dissertation Structure and function of human triceps surae muscle and tendon in aging is published in the series Jyväskylä Studies in Jyväskylä Studies in Sport, Physical Education and Health number 242, Jyväskylä: University of Jyväskylä, 2016, 87 pp. ISBN 978-951-39-6714-7 (nid.) ISBN 978-951-39-6715-4 (PDF). It is available at the Soppi University Shop and University of Jyväskylä Web Store, tel. +358 (0)40 805 3825,

Further information:

Lauri Stenroth,, puh. 050 3233862

Communications Officer Anitta Kananen,, puh. +358 40 805 4142

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