Loading to challenge movement
Loading should challenge a movement pattern, not change it.
The idea of loading a movement pattern is to put stress on your body. This stress, that hopefully over time you’ll adapt to and recover from, will facilitate you becoming a stronger, more resilient human. There are several mechanisms at work, namely increasing the muscle fiber size (getting jacked), increasing the ability to produce force (getting strong and stuff) and neural adaptations (your brain figuring things out).
Why?
There are several common reasons a movement pattern might change as loading increases:
Lack of confidence at a certain weight or number of reps, or even in a certain position or tempo
Insufficient strength or coordination
Lack of body awareness
Muscular imbalance, generally between the right and left or front and back
Protecting an (past or present) injured muscle or muscle group
What’s going to happen:
Nothing will immediately happen, but you’ll impair or limit the stress you're imposing on your body (which in turn will impair or limit your adaptation)
You’ll get hurt.
What do you do:
In the most basic sense, use loading to challenge your movement pattern without allowing it to change your movement pattern. After that:
Figure out (or have someone else figure out) when and why your movement pattern changes
Acknowledge and/or address your current limitation
*Disregard for the concept will result in lifelong disappointment and inability to cope with underachieving and inadequacies, causing you to lose your sense of purpose and fulfillment. Kidding.