Use walking at the beginning of a session as a physical and mental warm-up, and integrate it into your routine to build muscle.

noli's read

Starting a run with a few minutes of walking is an excellent habit validated by the American Council on Exercise (expert opinion) for gently waking up the body. A systematic review of the literature published in the African Journal of Biomedical Research confirms that this type of dynamic warm-up ideally prepares both the cardiovascular system and the mind for the exertion to come. However, the idea that walking "truly builds muscle" requires nuance depending on the individual profile. A ten-week observational study shows that walking improves muscle quality and tone primarily in sedentary or elderly individuals. Nevertheless, sports physiologists at the Hospital for Special Surgery (expert opinion) point out that to genuinely increase muscle volume, the body requires progressive resistance greater than that provided by standard flat-ground walking. Walking is therefore excellent for endurance and overall health, but should ideally be accompanied by strength exercises if one aims to build muscle mass.

the sources

No named source held this one up — that absence is part of the verdict.