It will not be an exaggeration to say that fashion drawing of a male figure is a rather neglected topic. Only a few books cover the subject for fashion drawing. In the meantime, plenty of female figure drawing resources exist for fashion professionals.
There are some objective reasons for that: women's fashion is a much bigger part of fashion industry. Also, women's fashion is overall more diverse due to the fact that practically all aspects of male fashion, one way or another, are absorbed by women's fashion. For example: trousers, pants, jackets and suits are as much part of fashion industry for women as it is for men. On the other hand, skirts and dresses are still (at least for now) offered only for women.
Nevertheless, at least partially, this lack of resources on the subject of male fashion figure drawing is due to the fact that in fashion drawing it is more difficult to design a prototypical, stylish and trendy male figure than female figure.
At the same time, traditions of methodical exploration of male figure drawing for visual arts are historically deep and remarkable. Starting from Doryphoros, continuing to Vitruvian Man by Leonardo da Vinci and up to the Modulor by Le Corbusier, the cannons of male figure were thoroughly explored and researched.
Successful drawing of standard prototypical male figure for fashion requires understanding of male figure anatomy, knowledge about muscle structure and proportions. Rendering of muscle structure when drawing male figure would help to create a more authentic look for a male figure drawing.