Morphological changes of lower leg muscles according to ankle joint position during sitting evaluated by gravity mri in young females.
Ryo Miyachi, Toshiaki Yamazaki, Naoki Ohno and 1 others
PMID 31320784WHAT IT FOUND
Sitting with the ankle plantarflexed or dorsiflexed was associated with uneven changes in lower leg muscle cross-sectional area along each muscle.
Some regions were larger while others were smaller, so ankle position did not change the whole muscle uniformly.
Key findings
01Soleus cross-sectional area changed unevenly along the muscle: the 1/4 proximal region was greater for plantarflexion, while the distal 1/4 region was greater for dorsiflexion or neutral.
02In the medial gastrocnemius and lateral gastrocnemius, the 1/4 distal region was greater for dorsiflexion or neutral than plantarflexion; in the TA, the 1/4 proximal region was greater for dorsiflexion, while the 1/4 distal region was greater for plantarflexion.
03Maximum cross-sectional area differed by muscle: soleus maximum did not differ, medial and lateral gastrocnemius maximum were greater for neutral and plantarflexion than dorsiflexion, and TA maximum was greater for neutral and dorsiflexion than plantarflexion.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 15 healthy young females with no pain or leg or spine history were studied, so the findings cannot be taken as evidence for patients with pain or leg or spine problems. The study measured muscle cross-sectional area, not strength, function, atrophy, or clinical outcomes. Muscle activity and contraction were not evaluated, so the influence of muscle contraction is unclear. The entire muscle was not always evaluated because the muscle belly was within the measurement interval in some participants but not others. No intervention was tested, so the study cannot show that ankle positioning prevents disuse atrophy or improves patient outcomes.
Declared interests
No potential conflicts of interest were disclosed. The work was supported by JSPS KAKENHI Grant Number JP16K01500.
The easy way to misread this
Do not conclude that sitting ankle position prevents muscle atrophy or improves strength. This study only measured muscle cross-sectional area in healthy young women; it did not test an intervention or patient outcomes.