Why some weights feel harder but don't make you bigger
Variable resistance training promotes greater fatigue resistance but not hypertrophy versus constant resistance training
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Variable resistance didn’t improve 1RM strength or muscle hypertrophy at all compared to constant resistance.
Most fitness culture assumes changing resistance patterns (like chains or bands) should lead to better overall gains. This study proves that for strength and size, it doesn’t matter.
Practical Takeaways
If you want to do more reps before failing (e.g., for sports, HIIT, or conditioning), switch to variable resistance machines or bands on leg press or squat variations.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Variable resistance didn’t improve 1RM strength or muscle hypertrophy at all compared to constant resistance.
Most fitness culture assumes changing resistance patterns (like chains or bands) should lead to better overall gains. This study proves that for strength and size, it doesn’t matter.
Practical Takeaways
If you want to do more reps before failing (e.g., for sports, HIIT, or conditioning), switch to variable resistance machines or bands on leg press or squat variations.
Publication
Journal
European Journal of Applied Physiology
Year
2013
Authors
S. Walker, J. Hulmi, M. Wernbom, K. Nyman, W. Kraemer, J. Ahtiainen, K. Häkkinen
Related Content
Claims (6)
If you get much stronger—like more than 20% stronger—on an exercise you’ve been doing for a long time, it probably means your muscles got bigger, not just your brain getting better at telling your muscles to work harder.
If you train with weights that change resistance throughout the movement (like using bands or machines that adjust), you can do more reps and lift more total weight before getting tired than if you use the same weight the whole time — and after 20 weeks, this difference is pretty big.
When you do resistance training with changing resistance (like bands or machines that get harder at different points), your body sends out quick chemical signals—like ERK1/2 and hormones—that seem to help you feel less tired over time, possibly making you more endurance-ready in the long run.
Whether you use machines that change resistance as you lift or keep the same weight all the way through, after 20 weeks of training, healthy men gain about the same strength and muscle size either way.
When you lift weights that get harder or easier as you move (like with resistance bands), your body reacts more strongly in the short term—your muscles get more tired, your stress hormones spike higher, and your cells show more signs of being worked hard—compared to lifting the same weight the whole time, even after training for 20 weeks.