A draw: the lying leg curl and the 45° back extension load the hamstrings about equally.
MyoHeat simulates the whole rep with muscle attachments and strengths from published research models, and shares the load between muscles the way the body is thought to: the least total effort that still moves the weight. The bars are each muscle's peak load in the rep, as a % of its maximal force.
Lying Leg Curl · 30 kg
Hamstrings29%
Tibialis anterior25%
Triceps brachii22%
Gastrocnemius17%
Deltoid16%
Sartorius13%
See it move
45° Back Extension · bodyweight
Hamstrings27%
Gluteus maximus20%
Deltoid17%
Erector spinae15%
Gastrocnemius14%
Triceps brachii13%
See it move
How sure is this?
Both exercises pass the model's literature checks: their prime movers in published EMG studies are among the muscles it loads most. The comparison is at each exercise's default load; change the weight in the app and the numbers move. It is an educational estimate, not training or medical advice. Sources, and where the model is wrong.
MyoHeat · All comparisons · Credits · Privacy