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.

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.

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.

Most of the research on how much to lift and how often was done on young men who already train—so we don’t know if the same rules apply to women, older people, or beginners.

If you lift weights more each week for each muscle, you’ll likely gain more muscle size—studies show about 3.9% more growth compared to doing less.

If you're already experienced with weight training, doing the exact number of sets your past logs suggest (1.2 times your usual) builds more muscle than doing a fixed number of 22 sets every week — and this is shown by measuring your thigh muscle thickness with ultrasound.