That depends. If a person is health-conscious, no.
I started playing soccer in 1982, when I was 8. I began bodybuilding in '87, when I was 13. I changed over to power lifting '94, when I was 22. Coincidentally, the same year I began studying Wudang Chuan Kung Fu. I took up competing in Olympic distance triathlons in 2012, when I was 38. In April of last year, as I was being prep for my triathlon season, I was hit by a car while running. Iended up in the hospital with badly sprained ankle and some bruises. So, since I couldn't run,I tuned back to lifting weights while I recovered. At 41, I was dead lifting a quarter ton. I recovered from the accident well enough within two months to train by running again, and although time was short, I was able to compete in 3 triathlons in that season.
This isn't exceptional to the athletic community. Anyone can be healthy at any age, but I often work with people who are half my age, but twice my weight.
So you ask - is 30 old? Depends on your lifestyle (i.e., nutrition, rest ratio, fitness level...).