When young men lift weights for 12 weeks, their short-term spikes in testosterone and IGF-1 after workouts don’t seem to predict whether they’ll gain more muscle or get stronger.

If young guys lift weights for 12 weeks, their muscle strength gains in the leg press don’t seem to be linked to how much their hormones spike right after each workout.

If young guys who lift weights do intense training every day for two weeks, their morning hormone levels might dip for a bit—but they bounce back within four days after stopping, so it’s just a short-term blip, not a long-term problem.

Even if your hormones spike a lot right after your first few workouts, that doesn’t mean you’ll grow more muscle or get stronger later on.

When young men lift weights regularly for 15 weeks, their body’s immediate hormone spike after each workout stays about the same—no matter how many times they do it. It’s like their body keeps reacting the same way every time, without getting used to it.

Even if your body has more of these muscle-building hormones like testosterone and IGF-1, it doesn’t mean you’ll grow bigger muscles from lifting weights over 12 weeks.