Add Yahoo as a preferred source to see more of our stories on Google. Marlo Alleva demonstrates a reverse plank knee up. Variation is the key to positive changes when it comes to our fitness.

Variation is the key to positive changes when it comes to our fitness. Sometimes our bodies grow too familiar with the same movements or our growing strength needs more intensity and challenges.

When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. There’s a good chance you’ve heard of the plank exercise if you have spent time working out at ...