Now THIS is my area of expertise. I research Cannabinoids at large as well as for my thesis on their effects.
Yes, Cannabinoids have been shown to produce negative growth changes in skeletal muscle cells in vitro in mammals, for a short duration of time and in a transient effect.
Essentially the cause a slowing of the electro-mechanical coupling(1), which is a fancy way of saying - slowing down the tim it takes the nerve signal to produce contraction (electro=nerve; mechanical=muscle)
References
(1)Cannabinoid signalling inhibits sarcoplasmic Ca2+ release and regulates excitation-contraction coupling in mammalian skeletal muscle./ Oláh T1, Bodnár D1, Tóth A1, Vincze J1, Fodor J1, Reischl B2, Kovács A1, Ruzsnavszky O1, Dienes B1, Szentesi P1, Friedrich O2, Csernoch L3. / Journal of Physiology (2016)