If you do a workout that targets both your upper and lower body, your muscles in those areas won't grow at the same rate or in the same way. Research shows that most combined workout routines lead to noticeably different muscle growth patterns between your arms and chest compared to your legs and glutes.

When you train your upper and lower body, your muscles don't all grow at the same rate. To get the best overall results, you probably need to adjust how much you train each specific area instead of using the same routine for everything.

Individual hypertrophic responses to resistance training are highly variable across muscle groups and are not consistently correlated between upper and lower body musculature.

Different parts of your body don't grow muscle at the same rate when you lift weights. Because your upper and lower body respond differently to workouts, you might need to adjust how much you train each muscle group to get the best results.

You can't really grow bigger muscles until you've done about 18 weightlifting sessions—your body needs time to adapt before it starts building real muscle.

Some people’s muscles grow a lot with training, others don’t—but if one person’s arms grow, their legs usually grow similarly, meaning your body’s natural response is more important than which muscles you train.