A near always asked question by new exercisers is what should I do first my cardio or my resistance training. Like all experts I will answer with the positive and absolute statement of "it depends." MUHAHAHAHAHAHA!
Actually it pretty set in stone depending on your goals. In freshman level classes you learn the SAID principle. Specific Adaptation to Implied Demands. Simply means you body will adapt to exactly what you do, no more than it has to. Knowing this we can plan how to include exercises that give you the most bang for buck as they say.
Most my clients are seniors or the obese. To maximize weight loss, and regain lost physical functioning, I insist on doing resistance first. Here is why. Once warmed up your body will be most capable of doing what you do first, meaning better output potential, the ability to work out a bit harder. Ability to work harder means more adaptations. Building a pound of muscle is 35 calories used perday even if you sit on your duff! They used to tell differently, they used to say do cardio first. Now that we know more that is not the case. Can you lose weight doing 30 mins cardio at 60% heart rate followed by 3 sets of ten resistance? Yes you can, but....
Second reason is for weight loss, doing your resistance first delete your glycogen reserves, your carbs, the sugar in your blood. So when you go on to do your cardio next, your body must use more fat as fuel and attempt to conserve carbs. Your post exercise burn. EPOC Post Exercise Oxygen Consumption will be higher. That is like free fat loss after your work out. Think of it as interest earned on your workout investment. Your body soon learns it will need to be more active, and will attempt to save carbs to work out, carbs are the preferred fuel over fats or protein. So while just going about your day, you are burning fat, more fat than those lazy bones that do not work out.
Athletes need to do the focus of the day first while having fresh legs to get the most out of the work out, and to be fresh to avoid injury. Like where I am training for distance I run first then do resistance MWF, and an abdominal circuit T-TH. I need to get used to high output at the end of the race with depleted blood glucose. I am not really an athlete, but you get the picture. Where a football player (NFL type) would do explosive sprints or lifts on days opposite of skill drills. A five mile run is pointless, and asking for injury.
Typical work out
10 mins warm up circuit jumping jacks, elbow to knee, free hand squats, stair steps, ect ect ect
resistance exercises like off the floor lifts, lunges, overhead presses, bench or cable presses, pull up or lat pulls, about 20 mins
30 mins cardio of what ever gets you going
10 mins stretching to cool down. (no, we also no longer stretch before working out, this is found to weaken the muscle before it ever works, causes micro tears before activity)