Let’s imagine a woman is performing a common bicep curl with a barbell.
After several repetitions of the exercise, she notices that the barbell seems to be heavier, and the exercise more difficult at the 90° elbow angle position than at any other position in the ROM (range of motion).
She has heard the term ‘sticking point’ to describe the hardest point of the lift.
She asks her fitness professional what causes this sticking point — is it simple fatigue, a mental block, or something else related to the position of her arm during the motion?
What would the fitness professional say?
A sticking point occurs when the weight feels heaviest in a certain area for the range of motion. Your strength fails to overcome the resistance at that point, and you miss the rep. Had you blasted past it, the rest of the range of motion would have felt easier, and you likely would have finished the rep.
The sticking point occurs because muscles struggle with poor leverage or when they function weakly. Throughout an exercise, leverage and muscle strength change. Not all positions tax your muscles the same.
Imagine a bench press. About halfway down, your elbows flare out away from your shoulders. You will feel this as a sticking point. At the top and bottom of the movement, your elbows are closer to your shoulders. These positions give better leverage, so you feel stronger.
You feel the most strong at the top since your elbows extend fully. The moment arm becomes zero or close to it, meaning the best possible leverage. At the bottom on the movement, your muscles stretch; This makes them weak. You may have better leverage compared with the middle portion, but not as good as you have at the top, so it feels hard here as well.
This means the bench press will feel hardest at the bottom through the middle of the exercise, not because you have a weakness. This happens due to mechanics and physiology that applies to everyone, without exception.
Keep in mind you can also fail at any point due to fatigue from the set.