The whole thing with Kimchis is that SHE answered the question as to what SHE believed was the reason for that zechus. She could have been totally mistaken. Chazal included this story in the Gemarah to illustrate a certain hashkafa in tznius. It was probably not told to Moshe Rabbeinu M’Sinai, and certainly not meant to imply it is halacha.
“Last I checked, the Torah tells us “Unishmartem M’od L’nafshoseichem” – and exercise is a pivotal aspect to keeping our bodies healthy. The Imahos may not have been joining Zumba and Pilates classes but they also were living agricultural lifestyles – filling water at the well, walking and moving constantly – they weren’t spending their days driving carpool, sitting behind desks, and basically leading sedentary lifestyles. Let’s not forget that Rivkah Imeinu gave water to ten camels – not an easy task – and Rachel and Leah brought their flocks to the well to water. “
It’s funny, I thought I had posted something similar to what you said here, but I don’t see the post, so maybe I deleted it before sending.