Plantarflexor Muscle-Tendon Properties are Associated With Mobility in Healthy Older Adults.
BACKGROUND
Muscle mass, strength, and power are known determinants of mobility in older adults but there is limited knowledge on the influence of muscle architecture or tendon properties on mobility. The purpose of this study was to examine the relationship between mobility and plantarflexor muscle-tendon properties in healthy older adults.


METHODS
A total of 52 subjects (age 70-81 years) were measured for 6-minute walk test (6MWT), timed "up and go"-test (TUG), isometric plantarflexion strength, Achilles tendon stiffness, triceps surae muscle architecture, lower extremity lean mass, isometric leg extension strength, and leg extension power. Partial correlations and multivariate regression models adjusted for sex, age, body mass, and height were used to examine the relationship between mobility (6MWT and TUG) and lower limb muscle-tendon properties.


RESULTS
Multivariate regression models revealed that Achilles tendon stiffness (p = .020), plantarflexion strength (p = .022), and medial gastrocnemius fascicle length (p = .046) were independently associated with 6MWT. Plantarflexion strength (p = .037) and soleus fascicle length (p = .031) were independently associated with TUG.


CONCLUSIONS
Plantarflexor muscle-tendon properties were associated with mobility in older adults independent of lower extremity lean mass, leg extension strength, or power. Plantarflexion strength was a stronger predictor of mobility than leg extension strength or power. The novel finding of this study was that muscle architecture and tendon properties explained interindividual differences in mobility. This study highlights the importance of the plantarflexors for mobility in older adults and provides understanding of possible mechanisms of age-related decline in mobility.
Gerontology Research Center and Department of Health Sciences, University of Jyvaskyla, Jyvaskyla, Finland. Department of Biology of Physical Activity, Neuromuscular Research Center, University of Jyvaskyla, Jyvaskyla, Finland. lauri.stenroth@jyu.fi.
Lauri
L
Stenroth
Gerontology Research Center and Department of Health Sciences, University of Jyvaskyla, Jyvaskyla, Finland.
Elina
E
Sillanpää
School of Healthcare Science, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, UK.
Jamie S
JS
McPhee
School of Healthcare Science, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, UK. Division of Clinical Physiology, School of Graduate Entry to Medicine and Health, University of Nottingham, Nottingham, UK.
Marco V
MV
Narici
Institute of Exercise Biology and Physiotherapy, University of Tartu, Tartu, Estonia.
Helena
H
Gapeyeva
Institute of Exercise Biology and Physiotherapy, University of Tartu, Tartu, Estonia.
Mati
M
Pääsuke
Institute of Myology, GH Pitié-Salpêtrière, UPMC UM76, INSERM U974, CNRS UMR7215, Paris, France.
Yoann
Y
Barnouin
Institute of Myology, GH Pitié-Salpêtrière, UPMC UM76, INSERM U974, CNRS UMR7215, Paris, France.
Jean-Yves
JY
Hogrel
Institute of Myology, GH Pitié-Salpêtrière, UPMC UM76, INSERM U974, CNRS UMR7215, Paris, France.
Gillian
G
Butler-Browne
Myology Center of Research, UMRS974 - UPMC Sorbonne Universités / U974 - Inserm / FRE3617 - CNRS/AIM, Paris, France.
Astrid
A
Bijlsma
Department of Rehabilitation Medicine, VU University Medical Center, Amsterdam, The Netherlands.
Carel G M
CG
Meskers
Department of Internal Medicine, Groene Hart Hospital, Gouda, The Netherlands. Department of Rehabilitation Medicine, VU University Medical Center, Amsterdam, The Netherlands.
Andrea B
AB
Maier
Department of Biology of Physical Activity, Neuromuscular Research Center, University of Jyvaskyla, Jyvaskyla, Finland.
Taija
T
Finni
Gerontology Research Center and Department of Health Sciences, University of Jyvaskyla, Jyvaskyla, Finland.
Sarianna
S
Sipilä
D000368:Aged; D000375:Aging / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000502:physiology*; D013710:Tendons / Q000502:physiology*; D016138:Walking
Gait Biomechanics; Muscle; Muscle architecture; Physical performance; Tendon stiffness