Cardio beforehand is more for someone who is looking to gain endurance, whether it is muscle or breathing. It is more important to favour a good cardio session and a little weight training for those who are preparing for a cross-country race (or semi-distance race).If, on the other hand, your objectives are to gain mass and strength, go towards weights before doing cardio. Be careful, after your session, try to avoid treadmills. Running melts, but also reduces muscle mass. Instead, go for a rowing machine or a bike, they are just as effective.For those who want to combine both, start with a little cardio, just to get a sweat going and then continue with a dynamic warm-up. Then do the weight training session of your choice and finish with cardio at a high pace (or a HIIT session).