Reliability of ultrasound assessment of the rectus femoris muscle thickness: intra-rater, inter-rater, and inter-day analysis accounting for age and sex.

Background: The rectus femoris muscle plays an important role in maintaining lower limb stability and biomechanical control during basic physical activities. Both reduced quadriceps strength and decreased muscle thickness of the rectus femoris, as measured by ultrasound, are associated with an increased risk of falls in older adults. We estimated the relative and absolute intra-rater, inter-rater, and inter-day reliability of the procedure.

Exerkines: A Crosstalk between Lactate Production, Exercise and Mental Health.

Muscle skeletal striated cells secrete a wide range of proteins called myokines or "exerkines", which in turn perform autocrine, paracrine, or endocrine functions. For being able to act in the communication between skeletal muscle, adipose tissue, and mainly the brain, exerkines play a prominent role and potential influence on health promotion. Furthermore, we detected in the literature that one of these potential therapeutic substances derived from muscle contraction is a molecule derived from glycolytic metabolism that in the past was largely marginalized, the lactate.