Still, the method is not a full replacement for everything a gym offers. Walking, even at interval intensity, mainly trains the cardiovascular system and the lower-body muscles used for that motion. It does less for upper-body strength, bone density that comes from loading the skeleton with weights, or the kind of muscle growth many people seek.
Experts who have looked at the trend note that resistance training remains important, especially as we age. Japanese walking can cover a large part of the recommended weekly aerobic activity, about two hours if done four times, but it leaves gaps in strength and mobility work.
The smart approach is to treat it as a strong foundation or a time-saving cardio option, then add simple body-weight exercises or light weights a couple of days a week if full fitness is the goal.
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