I've recently been having this argument with Paul. I've been doing leg days twice a week because I really want a squat booty for the pool this summer (and it might help my running, too). The thing is Paul is usually wrecked after leg day. He's gently hoisting himself off the couch by arm power alone while I prance up the stairs and laugh at his pain. So this last leg day Paul appointed himself
The 'I am going to puke, pass out, or die' face
I went up 20 pounds on leg extensions. I used him as a human squat rack (the Y doesn't have them) so I could squat 40 pounds heavier than I had been without a rack. I doubled the weight I was using for lunges. I PR'ed my leg press and calf raises. All the while Paul pushed me to go harder, squat lower, add more weight. I was CERTAIN that I would be walking like a cowboy the next day. I was wrong.
This discovery caused me to dig deeper into the science behind DOMS and post-exercise soreness. I found an article in the Journal of Experimental Biology where I learned just how wrong 'No Pain, No Gain' is. According to the authors the study was designed to 'test the hypothesis that symptomatic (i.e. detectable) damage is a necessary precursor for muscle remodeling'. In short, they wanted to see if muscle growth can happen without being sore.
PR!
Two groups of college students were tested. The first group was given three weeks of 'training' where they slowly ramped up their exercise. The second group was thrown in with the first on the fourth week with no ramp up. They just had to keep up as best they could. The second group showed higher levels of creatine kinase (an enzyme that is released when muscle is damaged through exercise, injury, etc.) and expressed more soreness and exertion than the first group. So, if more muscle damage means more growth, then the second group should have shown more gains right? Wrong.
Muscle gain and strength increases were equal across both groups. This study went as far as blood work and muscle biopsy to verify these findings! And it wasn't the only study that had similar findings and results. So my takeaway from all of this is that, if you know you're working hard and you're still seeing gains, then a lack of soreness the day after exercise doesn't mean you won't progress. It just means you can get off the toilet and climb the stairs without calling Life Alert! And I call that a win!