Putting the Cardio Before the Horse
If we had a nickel for every time someone asked us whether it's okay to do cardio and strength training on the same day -- and if so, in what order -- we'd have at least a quarter, a significant value in a land rife with parking meters. So we'll do our best to address those queries, ideally before the meter maid circles back.
First, for most Moving Crew readers -- i.e., people who exercise at light to moderate intensities -- performing both on one day is fine, according to the American College of Sports Medicine. You're not putting high enough demands on your body to significantly compromise the value of either activity or risk injury.
So do your 20 minutes watching CNN on the treadmill, and follow it up with your half-hour set of strength training moves. Or do a strength training circuit of six exercises with no rest between sets and keep your heart tapping throughout. Godspeed, ya big galoot.
The asterisks begin to fly as intensity levels increase.
"You wouldn't want to have a heavy lifting day after running 10 miles" on the same day, says William Kraemer, a professor of kinesiology, physiology and neurobiology at the University of Connecticut. That's because your body is busy restoring energy, rebuilding damaged tissue and recovering hormones exhausted during the first exercise bout.
After hard activity, "your body wants to say, 'We're in repair mode,' " Kraemer says. If you jump to another demanding task while your system is busy synthesizing protein to repair stressed muscles, the body goes back into metabolic mode, which interrupts the recovery. "You want to be fully metabolically and neurologically capable for the big stuff. Whatever [activity] you do first will have the highest quality," he says.
Kraemer suggests following a tougher strength session with a light run, or doing hard interval cardio training before light lifting.
While the strength-cardio sequence matters little, Walter Thompson, a kinesiology, health and nutrition professor at Georgia State University, does recommend an ordered approach within a strength training session.
This essentially involves doing the bigger-payoff moves earlier in your workout. So, for example, work your large muscles (quads) before smaller ones (abductors); perform multi-joint exercises (bench press) before single-jointers (biceps curls).
A related question we hear often (hey, cut us a break -- we need another quarter) is whether doing too much cardio will burn away muscle. Thompson and Kraemer say the answer for most people is no.
But lots of cardio -- say, an hour of intense activity five days a week -- can deplete muscle glycogen, especially in people on low-carbohydrate diets. (Is anyone still on a low-carb diet?) This could compromise muscle growth. Carbs are our bodies' first choice as an energy source, and if there's not enough available the body will eventually tap into protein stores for energy -- stores that would otherwise be used to strengthen muscle.
But, Thompson says, even a robust cardio routine should not interfere with muscle mass increase in people with a balanced diet of about 65 percent carbohydrates, 20 percent fat and 15 percent protein.
There's a little more to this -- real sciencey stuff about muscle fiber size -- but the heavy lifting is done (figuratively) and we've got to run (literally: our meter expires in 30 seconds).
-- John Briley