I'm a 115lbs 35-year old male and I've recently put aside my weight training to focus on cardio. I've always jumped rope to warm up but now I'm really trying to focus on it and I've noticed something...what seems to limit how long I can jump for is my feet. Is that normal? It's not my arms, not my breathing, not my heart, but my feet. If it weren't for my feet it, feels like I could go all day.
I jump at a rate of 2.5 jumps per second barefoot on a carpet floor with 3/4 thick foam mats on top. That gets my heart rate up to about 120 BPM. I can only do sets of about 300 jumps at a time before I have to rest my feet. Although recently, putting everything else aside for jump rope seems to have increased to 400 and sometimes 600 jumps per set.
I'll do a set and wait a minute or two before doing another (sometimes I end up waiting way too long). And this will continue for 30 minutes to an hour or so (the longer it goes on for, the more likely I'm waiting too long between sets). Regardless of how long I actually do it, I don't think I ever get more than 3000 jumps in total because I probably start slacking as time goes on and take longer breaks.
Conventional wisdom seems to indicate that with proper form your arms should get tired first but this doesn't happen. Nor does it feel like I'm out of breath or that my heart is beating too fast.
What gives? I tried Googling but literally every result is about your arms getting tired and not your feet.
And suppose my feet didn't get tired, does the fact that neither my breathing nor heart make me feel like I have to stop mean I should jump even harder?