Many people need to do their cardio and strength training in the same exercise session because of their schedule or need to use fitness center facilities and/or equipment. Even experienced exercisers sometimes ask the question: should I do cardio or strength training first? Unfortunately, no one answer applies to everybody. It all depends on what your goals are. Once you've set your goals, though, it's easy to decide which to do first.

If you're a runner, swimmer, or cyclist (or all three) and strength training is intended to improve your sports performance and prevent injuries, do your cardio before your strength training. If you do strength training first, you will deplete the tremendous amount of energy you need to do hard endurance training. Training for endurance sports is so taxing, in fact, that many athletes don't feel like doing strength training afterwards. Don't go to that extreme, but you do have to be realistic. Your weights and reps are going to be less than what they would be if you hadn't done cardio exercise first. As long as you're putting forth your best effort and making progress, just relax and accept it.

If you're a strength athlete, such as a weightlifter, football player, or thrower, and cardio is intended to give you more endurance for your lifting or throwing and control your weight, do your cardio after your strength training. Your goal is to lift the most weight, the most times that you can, so you need to save the cardio for after your strength training. Doing cardio first will sap your strength.

If you're preparing for a military or law enforcement physical fitness test, you need to find out the order of events in the test. Are the strength exercises done before the run and/or swim, or after? Whichever it is,do your workout in exactly the same order as the test is given. If for some reason you can't find out the order of events in the test, do your cardio after strength training. That's the typical order.

What if you're training for all-around fitness? In that case, alternate doing cardio before strength training and doing cardio after strength training. That will ensure equal development of both cardiovascular fitness and strength; plus, it's more realistic. Primitive humans, who were always in excellent physical condition, usually walked and jogged to the hunt or battle. Then they sprinted and did strength work (spear throwing, fighting, wrestling, etc.) though they often would have to chase game or enemies (or run from them) afterwards too. On the other hand, sometimes they were surprised by an animal or ambushed by enemies and had to do their strength work first to defend themselves, and then do some cardio afterwards to get away. To be fit the way humans were before city life softened us up, you need to be able to do either cardio and strength training when you're partially fatigued.

I hate it when authors say you have to decide for yourself and won't give a definitive answer, but you can see that this is a question that you really do have to answer for yourself. To put it simply, decide which activity is most important to your goals: cardio or strength training. Do that one first. If it's neither, then alternate doing one before the other. Is that definitive enough?