You can’t just count how many reps you do to know if your workout is good enough — how long your muscles are under strain matters just as much, maybe more.

When you lift weights, how much total work you do matters more for getting stronger and bigger than whether you use heavy weights with few reps or light weights with many reps.

If you lift weights until you can’t do another rep vs. stopping just before failure, you end up doing about the same total amount of work over eight weeks — same number of reps and same weight lifted.

In previously trained adults, lifting weights with 0–1 reps left in reserve produces the same total amount of work over five weeks as lifting with 4–6 reps left in reserve, even though the latter feels harder.

For men who regularly lift weights, increasing their weekly training volume by 30% from about 12 sets led to a measurable improvement in how many repetitions they could perform at 70% of their maximum strength, but increasing volume by 60% or keeping the same volume did not produce the same improvement.

Guys who keep their usual workout routine get stronger than those who do a lot more lifting — sometimes doing more isn’t better for building strength.