Elliot wasn't sure if he could classify his mitochondrial experiments as a success. He definitely had more power available for physical activity, but it turned out to be a two-edged sword.
When testing his newfound strength, he punched a huge crater into the side of a mountain. Which caused a significant rock slide. This was a significant improvement to his strength, and he felt he had only scratched the surface of what he was potentially capable of. The reason he couldn't push me the test further was because his arm basically exploded. The bones of his hand and forearm shattered, and the flesh ruptured.
It was a dizzying sight for someone who has spent uncounted years nigh invulnerable. Before he could start to process the pain though, he watched in shock as his flesh reknit before his eyes.