I actually got real evidence for this recently. I used to do regular strength training, but when my second child was born I stopped for about 2 years. I had als

I actually got real evidence for this recently. I used to do regular strength training, but when my second child was born I stopped for about 2 years. I had also been doing occasional (1-3x/yr) DEXA scans to check my body composition. When I re-scanned myself after about 2 years off, I had gained quite a bit of fat and lost muscle in most places, but gained muscle in my arms/upper body. I felt notably stronger from carrying her (and her growing older sister) and that confirmed it.