The study looked at whether people with ALS have lower levels of the MGF (IGF‑1 Ec) gene in their muscles and if a short, low‑intensity workout or stretch would raise those levels. It found that ALS patients start out with the same amount of MGF as healthy folks, and a single bout of light exercise or mechanical stretch didn’t change MGF levels in either group.

In an animal model of ALS, intramuscular administration of MGF, the IGF-I Ec gene splice variant, improved muscle strength and increased both motor unit and motor neuron survival. Here we investigated whether there is a deficit in MGF production in the muscles of patients with ALS. We used complementary in vivo and in vitro techniques to study the IGF-I splice variant response of human muscle to exercise or mechanical stretch. We assessed the levels of MGF and IGF-IEa mRNA in muscle biopsy samples from healthy subjects and patients with ALS, before and after exercise. We used primary muscle cells to build three-dimensional collagen constructs and subjected them to a ramp stretch. Patients with ALS had similar baseline levels of MGF and IGF-IEa mRNA to healthy controls. No up-regulation was seen in either group within a short time of a single bout of low intensity exercise. Three-dimensional human muscle constructs also detected no response to a mechanical stretch from either control subjects or ALS. We conclude that the pathology of ALS does not include a deficit in baseline levels of MGF and IGF-IEa mRNA splice variants in muscle.