What is "These studies"? Are you referring to all studies? All observational studies? Something else?
While I can't debate "These studies" without knowing what you're referring to, this specific study provides a clear explanation of the study cohort and there's no sign that anyone was excluded or otherwise cherry-picked.
I updated my comment, I realize I was definitely vague in my criticism.
I've found that digging deeper into studies in the past that they would leave out people with heart conditions (specifically with caffeine studies) and not state that _anywhere_ in documentation. And this only came out from investigations.
While I can't debate "These studies" without knowing what you're referring to, this specific study provides a clear explanation of the study cohort and there's no sign that anyone was excluded or otherwise cherry-picked.