Employees who keep themselves fit through participation in sport are probably far less likely to have time off work than their more sedentary colleagues. (e.g.. they're less likely to be off work with heart or respiratory problems, with diabetes-related problems derived from obesity, or with stress-related illnesses). It would seem extremely unjust to penalise them when they suffered a sports injury!
Elective surgery is not the same as illness or injury and it would be reasonable to expect employees to undergo such surgery (and the recuperation therefrom) during their holidays. However, if an employee was hospitalised through unexpected complications resulting from such surgery, it would seem equally reasonable to treat these in the same way as any other unexpected infirmity.
When I was in teaching, staff with more than one year's experience could take up to 6 months off sick every year with full pay guaranteed. Beyond that, the next 6 months was guaranteed at half pay but the education authority had the discretion to pay the full rate (which it often did). Given that we got 3 months holiday per year anyway, that was quite a generous package. In practice, about 90% of the staff hardly had any time off. (I only had 2 days off sick in my 15 years in the profession. Several of my colleagues had worked far longer than that, with never a single day off). The other 10% of the staff were hardly ever there.
Chris