It's a question for the ages - or at least, for the fitness obsessed era in which we live. Between running and swimming, which is the better form of exercise?

In order to answer this question, we have to ask another question: What, exactly, constitutes better? Better for what? For total caloric burn?  Overall muscle conditioning? For cardiovascular health? For your joints?

The truth is that all exercise is good for you, but to best answer the question of which is better, we're going to break it down into specific categories.

For time. Even at your most intense lap pace, a brisk run will always burn more calories - if you were to run and swim for the same amount of time, that is.

For distance. Because swimmers use more of their total body to move themselves, they will burn more calories swimming the same distance than a runner who runs that same distance. This is because water is about 800 times more dense than air, so the effort to move the same distance will result in greater energy (and therefore calories) expended.

In other words, both can help you slim down and get your body ready for the beach, the bedroom, and anywhere in between.

While both forms of exercise do work your entire body, swimming allows your entire body to work against the resistance of the water, so you're getting a more total body muscle conditioning, as well as a more balanced workout. Yes, your upper body does get some action during your run, but your legs are doing most of the grunt work. When you swim, both upper and lower body get a pretty even workout.

This should come as no surprise. Whereas running is a high-impact sport, swimming is super easy on your joints. This is definitely the pick for people with joint issues or who are recovering from an injury.

In a 2008 study published in Sports Medicine & Doping Studies, researchers found swimmers and runners had almost identical rest heart rates, coming in at around 57.5 beats per minute.

While swimmers have lower heart rates swimming than runners do running, and while this may seem to insinuate that the heart wasn't getting as much of a workout, researchers believe this is not because of actual effort, but because swimming is done while prone, which facilitates greater flow of blood back to the heart. That, and the prone position allows your heart to pump more blood with each contradiction. So your heart is still working hard when swimming, and you are still getting the same heart health benefits as running, but your heart is working more efficiently in the water.

The truth is the best exercise is the one you’ll actually do. This makes the better exercise between running and swimming the one you’ll enjoy the most on a mental and physical level. Love chasing the runner’s high? Then slap on your Asics and hit the road. Love cutting through the water? Then don your Bondi swimwear and take a dip.

But know this: you don’t have to pick just one! Do them both, and reap all the perks of getting active on land and in water.