These two studies were part of the Women's Health Initiative (WHI) dataset, which investigates post-menopausal women. The study linked in OP used a published da

These two studies were part of the Women's Health Initiative (WHI) dataset, which investigates post-menopausal women. The study linked in OP used a published dataset, while the exercise study used WHI participants, meaning there was already a lot of data on the participants' health. So, the studies show effects on only women because they investigated only women. Why post-menopausal women? Because menopause is a threshold event for aging that isn't seen as clearly in men. Also, it's easy to simulate (ovarectomy) and reverse (hormones) in model systems.