Double down--should you run twice a day?

Run twice in one day?! You don't have to be an elite athlete to divide and conquer

Heading out for two runs in a single daylogging doubles or two-a-daysis standard practice among elites. But most mortals wouldnt 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, youre 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. Heres when it makes sense to double upand how to do it safely. (Just to be safe, follow these 10 Golden Rules of Injury Prevention no matter how often you run.)


Little Time, Big Dreams
Cumulative mileage mattersno 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 weekand 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 dont 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 cant 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. To speed up results, Recover Right With Whole Foods.

Midweek Mileage Crunch
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. Youll also enjoy two postexercise 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 its better to take two runs that you feel really good about than one that you just slog through, says Hudson. That said, theres 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.

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Aiming for a PR
Seasoned, experienced runners with a solid aerobic base and a lofty time goal can increase strength and speed with a regimen of two daily targeted workouts. This approach is for people who have pushed their training as far as they can and are looking for an extra boost, says Magness. To your quality days, add a second, shorter (one-half to three-quarters the length of your first run) intense workout tailored to your specific race goal. So if youre trying to improve speed over distance for a half or full marathon, follow a morning tempo run with an afternoon endurance-building session of, say, 3 x 1-mile repeats at slightly faster than tempo pace. If youre targeting a PR in a 5-K or 10-K, do your usual speedwork in the a.m. and add shorter, faster hill repeats or intervals in the p.m., says Hudson. For example, 4 x 2-kilometer repeats at 10-K pace with three minutes recovery followed by 4 x 400 meters at 3-K pace with one-minute recovery. Most workouts, you come in pretty fresh, says Magness. With these blocks, youre coming in tired. You have to use muscle fibers you dont typically use, so your body has to develop a different strategy to dig a little deeper. Such efforts make your warmup, cooldown, and recovery even more critical. On rest days, really rest: Take the day completely off. It can actually make people smarter about their training to know these double days are coming up, says Hudson.

The Pros and Cons of Back-to-Back Marathons

But Don't Overdo It!
Follow these guidelines for staying healthy on the double.

Build a base Accrue 18 to 24 months of running four to five times a week before adding doubles.

Run by time Start with a second run of 20 minutes. Over time, build up to no more than 45 minutes.

Ease into it Begin with one double. After a week or two, add a second. Build up to no more than four.

Space it out Allow four hours between doubles, and be sure to hydrate and fuel well between each.

Stay alert If you start to feel sick, run- down, crabby, or achy, back off. Youre probably overdoing it.

Source:  Runner's World