Scott….just listened to your aging (aged) athlete Evokecast…..Thanks! from me who is one year younger and one less knee replacement than you and still ski touring passion….you mentioned still doing intervals as an old guy, though the idea that they are still icing on the cake of endurance training…..my question is anything “different” to recommend for intervals for an older (70ish) but not much injured guy….ie length of time (of active vs rest in between etc), intensity, multiples compared to your recommendations for typical/younger endurance training intervals?? formulas to Do or Not Do?? Thanks, Chet Roe