What does resistance atrophy mean in weight lifting?

Answer 1

Resistance atrophy is the reduction of resistance over time, particularly through a movement. When you move free weights quickly, the resistance atrophy is due to momentum of the weight reducing the amount of energy required to continue moving the weight.

Elastic "strength bands" are more resistant to short-term resistance atrophy, because they tend to provide more resistance as they're stretched. However, such elastic bands can become worn out over time, contributing to long-term atrophy.

Body weight exercises, which use the mass (or a percentage thereof) of the person doing the exercise to provide resistance with gravity. Momentum-based resistance atrophy is in play here, as well as long-term atrophy due to the usual loss of body mass that occurs with exercise, though this will cap when a healthy weight is reached, and may even reverse as muscle mass is added.

Answer 2

Muscular atrophy is the wasting away lean muscle mass. It is usually undesirable.