Doctor’s Orders

Take two runs a day and call me in the morning

It’s Saturday morning. You’re about to head out the door to run your favorite trail for an hour when you get called into work for the day. You cut your run to 30 minutes so that you can get to work on time, thinking that perhaps you will run another 30 minutes in the evening. You ask yourself, “Is it OK to break up one run into two? Will I still get the same benefit?” Excellent question.

Running double workouts in one day might seem hardcore. While many competitive runners run twice a day to log a large weekly training volume, double workouts aren’t solely for elites.

Strategies for Running Twice a Day

> Run very easy during your morning run.

> Allow at least five hours between your workouts to recover.

Consume about two calories of simple carbohydrates like glucose per pound of body weight (0.5 gram/pound)

> immediately after your first run to speed recovery. For a 150-pound runner, that means consuming about 300 calories of carbohydrates, which equals about three 8-ounce glasses of chocolate milk. Keep consuming carbs over the next few hours.

Rehydrate after your first run by drinking 15 ounces of water or electrolyte drink per pound of body weight lost during your run.

> Start by doing two-a-days just once or twice per week, cutting the length of the single run you’d normally do by 15 minutes. Don’t do more than 10 to 11 runs a week. For example, if you normally run 60 minutes, cut that back to 45 minutes and do a second run of 30 to 40 minutes.

> When to Do Doubles

If you run less than 30 to 40 miles a week, it’s better to run just once a day. Running five miles all at once is better than running two miles in the morning and three miles in the evening. Longer single runs build endurance and make you a better trail runner (plus, you get to see more of the trail!).

Once your weekly mileage reaches a level at which your daily runs are averaging an hour or more and your weekend long run is one-and-a-half to two hours, it’s beneficial to run twice a day at least a couple of times a week as you further increase your weekly mileage rather than to extend the length of all of your runs. Of course, running twice a day takes additional time out of your day and makes it more difficult to recover between runs, so you will need to factor that in too.

Proper nutrition after your first run is important so you can  quickly recover between runs. Consume 200 to 400 calories of carbohydrates and protein immediately after your first run, and spread the runs at least five hours apart.

> Spread the Stress

The biggest advantage of doubling up is that it allows you to increase your training load while minimizing stress on your body and reducing recovery time. Both physically and psychologically, it’s easier to run four miles in the morning and six miles in the evening than it is to run 10 miles (or even eight miles) all at once.

The only time you should avoid running twice is on the day of your long run. Your long run should always be completed at once, especially if you’re training for long trail races, because of important endurance and metabolic aspects of the long run that can only be obtained by continuous running. For example, one of the purposes of long runs is to deplete (or severely lower) muscle glycogen, your stored form of carbohydrates. When you deplete muscle glycogen, lots of interesting adaptations occur, including the storage of more fuel in your muscles, a greater reliance on fat by your muscles and an increased capacity of your liver to make more glucose for energy. If you break up your long run, you won’t deplete your glycogen fuel tank, so you’ll miss the opportunity to make the adaptations. Long trail runs also prepare your muscles, bones, tendons and ligaments to handle the stress of running on trails and callous you for the psychological fatigue that accompanies running for a long period of time.

> Hormones

Many of the adaptations you make from training are initiated by signals from hormones, which are amplified and transmitted via signaling cascades and lead to protein synthesis. This signaling is fast, occurring within minutes of completing a workout.

When you run twice a day, you get two hormonal responses and thus two opportunities for adaptation to training because you have more frequent signals for protein synthesis. Repeated hormonal responses lead to a concerted accumulation of structural and functional proteins in your muscles, like more mitochondria and enzymes, improving your aerobic fitness and enabling you to run faster.

> Metabolism

If you want to lose weight, running twice a day can be an effective strategy. For one thing, it allows you to raise your daily and weekly mileage, which increases the number of calories you’ll burn. Running also elevates your metabolic rate for a few hours after you stop, as your body uses fat as energy to recover and return to homeostasis, so splitting your run into two shorter runs gives you two separate elevations in your post-workout metabolic rate, which gives you two opportunities to burn more calories during the day.

A study published in British Journal of Sports Medicine had women run for 50 minutes at 70-percent VO₂max one day and twice for 25 minutes at the same intensity another day. A similar study published in Canadian Journal of Applied Physiology had men cycle for 30 minutes at 70-percent VO₂max one day and twice for 15 minutes at the same intensity another day. Both studies found that the combined increase in post-workout metabolic rate was higher after two workouts compared to one.

Many of my athletes training for long races have benefited from two-a-days when running high mileage. They say it keeps their legs feeling fresh while still accumulating a lot of miles. When they run more than an hour a day, it’s harder for them to bounce back the next day for a workout. Any time I have coached a runner who runs more than 50 to 60 miles a week, he or she feels a lot better when breaking some of the runs up into two runs a day. You’ll notice a difference, too.

So, the next time something unexpected happens that forces you to cut your run short, don’t fret, just break up your run into two. It may be the double boost you need.

Dr. Jason Karp holds a Ph.D. in exercise physiology, and is a nationally recognized coach and owner of RunCoachJason.com. He is the author of five books, including 101 Developmental Concepts & Workouts for Cross Country Runners, 101 Winning Racing Strategies for Runners and Running for Women