No pain, no gain, no idea what half these terms mean.
The unofficial motto of every gym that essentially glorifies suffering as a prerequisite for improvement. It was probably invented by someone selling ibuprofen, and it's been used to justify questionable exercise decisions since the dawn of spandex.
Short for natural, meaning someone who builds muscle without performance-enhancing substances, which on the internet is apparently everyone and simultaneously no one. Claiming to be natty is the fitness world's version of "I woke up like this."
Completing the second half of a race or workout faster than the first half. The pacing strategy that separates the disciplined from the over-enthusiastic who died at mile 2.
Strength gains from your nervous system learning to recruit muscle fibers more efficiently, not from building bigger muscles. It's why beginners make huge strength gains before visible muscle appears, frustrating mirror-watchers everywhere.
The alleged automatic credential that natural (non-steroid using) athletes can play to explain their slower progress or smaller physiques. The fitness equivalent of 'I have a boyfriend.'
The theoretical ceiling of muscle mass and strength achievable without performance-enhancing drugs, calculated through various formulas that people on steroids love to exceed while claiming natural status.
The controlled lowering phase of an exercise, typically performed with heavier weight than you can lift concentrically. It's the part of the rep where gravity becomes your training partner and your muscles scream about the betrayal.
The miraculous rapid muscle growth and strength increases experienced by beginners in their first 6-12 months of training. Enjoy it while it lasts, because nothing will ever feel this easy again.
The practice of consuming specific nutrients at strategic times relative to training to optimize performance and recovery. The fitness equivalent of believing that eating cake at midnight has fewer calories.