Muscle function in Turner syndrome: normal force but decreased power

Area of Science:

• Pediatric Endocrinology
• Bone and Mineral Metabolism
• Genetics

Background:

• Turner syndrome (TS) is associated with decreased bone mineral density and increased fracture risk.
• The exact mechanisms linking hypogonadism, SHOX gene haploinsufficiency, and bone fragility in TS remain unclear.
• Muscle dysfunction is a potential contributor to increased fracture risk in TS.

Purpose of the Study:

• To investigate if muscle dysfunction contributes to increased fracture risk in patients with Turner syndrome.
• To determine the influence of menarche, hormone therapy, fracture history, and genotype on muscle function in TS.

Main Methods:

• A cross-sectional study involving 60 patients with TS and 432 healthy controls.
• Muscle force (Fmax) and power (Pmax) were assessed using a Leonardo Mechanograph Ground Reaction Force Platform.
• Muscle function parameters were analyzed using linear regression adjusted for age, weight, and height.

Main Results:

• Patients with TS exhibited normal maximal muscle force (Fmax).
• Maximal muscle power (Pmax) was significantly decreased in patients with TS compared to controls.
• Menarche, hormone therapy duration, fracture history, and genotype did not significantly influence muscle function parameters.

Conclusions:

• Normal Fmax in TS suggests that decreased bone strength is likely due to a primary bone deficit, not inadequate mechanical loading.
• Reduced Pmax indicates impaired muscle coordination in patients with TS.
• These findings highlight a potential role for muscle coordination deficits in the pathophysiology of bone fragility in Turner syndrome.