Im guessing you mean it as a question because you have asked questions before.
When a muscle is eccentrically lengthened, the energy requirement drops substantially because ATP breakdown and heat production are both slowed. This pretty much causes an increase in metabolism.
The more oxygen consumption in training leads to an overall decrease in oxygen requirements and increased force/power production.
Also, most people know the concentric phase of lifts and just release for the eccentric, even though the eccentric can massively increase muscle hypertrophy and strength.