Free tool
Resistance profile explorer
See where in the rep each version of an exercise is hardest, and why.
Short answer: A free weight is hardest where it is furthest sideways from the joint, a cable where it pulls at right angles to the limb, and a band where it is stretched most. So a dumbbell lateral raise is hardest at the top, while a cable version loads the bottom too.
Main muscle: Biceps
Standing dumbbell curl
free weightHardest in the middle of the rep
The lever arm is longest when your forearm is level with the floor.
Preacher curl
free weightHardest at the bottom, with the muscle stretched
The pad sets your upper arm forward, so the hardest point moves to the bottom.
Incline dumbbell curl
free weightHardest in the middle of the rep
Still hardest mid-rep, but your arm starts behind you, so the biceps are longer throughout.
Cable curl facing away
cableHardest at the bottom, with the muscle stretched
The cable pulls from behind, keeping tension when the arm is straight.
Band curl
bandHardest at the top, with the muscle squeezed
The band stretches most at the top.
Based on mechanics: where the weight, cable or band is hardest to move. Machines differ between brands.
What a resistance profile is
It is how hard an exercise feels at each point of the rep. It depends on the lever arm: the horizontal distance between the joint and the line the weight or cable pulls along.
Why it matters
Exercises that are hardest when the muscle is stretched have built more muscle in several studies (Maeo et al., 2021; Maeo et al., 2023).
Machines and bands
Machines use cams that change the profile, and these differ between brands. Bands get harder as they stretch, so they load the top of a rep most.
Scientific sources
- Maeo et al. (2021). Greater hamstrings muscle hypertrophy but similar damage protection after training at long versus short muscle lengths. Medicine & Science in Sports & Exercise.
- Maeo et al. (2023). Triceps brachii hypertrophy is substantially greater after elbow extension training performed in the overhead versus neutral arm position. European Journal of Sport Science.
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Educational information for adults aged 18 and over. It does not diagnose, treat or manage any medical condition. If you have a health condition, or symptoms that worry you, speak to your doctor or a health professional.