Running Twice A Day – What’s The Point?

Heading out for two runs in a single day–logging “doubles” or “two-a-days”–is standard practice among elites. But most mortals wouldn’t dream of it: not enough time and too much injury risk. “There is a misconception that doubles are something only high-mileage, elite runners do,” says Steve Magness, an exercise physiologist and cross-country coach for the University of Houston. “But a lot of runners can benefit from them.” Including time-crunched folks trying to squeeze in miles and veterans looking to step things up. For good reason: Studies suggest doubling up and running in a depleted state can boost fat-burning, train the body to use glycogen more efficiently, and stimulate mitochondria production (more mitochondria can delay fatigue). “By shortening the time between runs, you’re challenging your body to recover faster,” says Greg McMillan, an exercise physiologist and coach in Flagstaff, Arizona. “And a faster recovery is a good thing.” But bad things can happen if you overdo it. Here’s when it makes sense to double up–and how to do it safely.

“Cumulative mileage matters–no matter how you do it,” says Brad Hudson of Hudson Elite Marathon Performance in Boulder, Colorado. You can boost your total miles by doubling once a week–and still keep a rest day. Four to 10 hours after a key workout like an interval session or a tempo run, go for an easy 20- to 45-minute run, and don’t fret about pace. This will boost mileage and aid recovery from the first workout by increasing blood flow to the muscles and flushing out lactic acid and other metabolic waste products. The result? Fresher legs for your next run. “The best massage you can get is from a second run,” says Hudson. On days you can’t bear the thought of lacing up again, try pool-running, cycling, or the elliptical. Such options offer similar recovery benefits without  the pounding, says Hudson.

No doubt, it can be tough to run six to eight miles on a Wednesday. Divide the run in two, and you can reap a surprising number of benefits. For example, logging two 40-minute runs delivers a double boost of human growth hormone (production peaks about 40 minutes into a run), which helps build and repair muscle. You’ll also enjoy two post exercise spikes in your resting metabolic rate, which could aid in weight loss. And finally, you can push the pace a bit on the shorter runs. “Sometimes it’s better to take two runs that you feel really good about than one that you just slog through,” says Hudson. That said, there’s simply no substitute for the weekly long run when it comes to building endurance, muscle strength, and mental readiness, particularly if you have a half or full marathon in sight. Maintain your long run and key workouts and split only midlength recovery runs, says Magness.