Likely a medical checkup.
And given the letters BMI was shown and her behavior afterwards, she might be a bit above the average value on the BMI index.
So why does that "other" exercise promote sleep? Would've thought it being closer to the heavy side instead of light in the exercise spectrum. Is it just the adrenalin?
@Amenohi Not only it tenses and then relaxes all muscles in the body, but it also releases a lot of oxytocin. And that stuff, among other things, regulates blood pressure and makes you sleepy when in big amounts. It also a metabolite of melatonin, after all.
SO yes, it can be perfectly counted as an exercise. There are even diets based around it.
Going by the tummy squeeze her BMI is far below thicc. No square or outwards stretched waist line. What the hell is she going on about ... The body standards in this manga are WTF.