If running once a day is good, running twice a day is better, right? Well, not so fast — literally and figuratively.
‘For the elite half or full marathoner, adding doubles can increase running mileage pretty safely and can actually enhance recovery,’ says Anh Bui, DPT, CSCS, level 1 USATF-certified coach of Run Resiliently Physical Therapy.
Greg Laraia, a running coach at Motiv in New York City, adds that the primary benefit is accumulating more volume, which ideally adds up to more durability and/or speed on race day.
But, the strategy ‘has to be for the right person and it has to be done very meticulously,’ Bui says.
So before you start adding another run to your days, make sure you can check off these benchmarks—and follow the tips from Bui and Laraia to do doubles right.
How to know it’s time to add doubles to your trainingYou run at least six days a week
First and foremost, you should be maximising your single-run days by running six days a week as much as you possibly can, Bui says.
Laraia agrees: ‘I’d rather see somebody just add more singles than add a double.’ Running singles typically allows you 24 hours in between runs to fully recover.
That said, once you’re consistently running six days a week, with some of those runs in the double digits, you may want to consider doubles. ‘For a lot of advanced marathoners, if you do 14 miles in the morning, your fatigue could be a lot higher [than if you] break that up into a 10-mile session in the morning and then a four-mile easy run in the evening,’ Laraia says.
The doubles strategy is especially helpful for those clocking high mileage, allowing you to maintain volume while adding in recovery breaks.
You’re pressed for time or want to run-commute
There are some exceptions to the above. If your marathon pace is 12 minutes per mile, for example, and an eight-mile run may take too long to get in before work, splitting it up (and doing five miles in the morning and three after work, for example), may be a good idea, per Bui. (However, doing so may not result in the same benefits since it’s not as much of a volume-adding strategy as a time-saving one.)
Similarly, Laraia and Bui agree that city dwellers who can run-commute home from work may naturally benefit from this approach.
You’re not injured or prone to injury
You have to be sure your body can handle the additional mileage. The number-one sign that it can’t is if you’re already managing an injury or if you have a long history of injuries, Bui says. ‘It wouldn’t make sense to add intensity [or] volume to that,’ she says, adding that you need to be able to fully recover from one run a day before adding a second.
‘Every time you’re going for a run, you’re still pounding the pavement,’ says Laraia, adding that he doesn’t love the word ‘recovery run’ for this reason. If running already exacerbates an injury or issue, running more is certainly not going to help it, Laraia says.
You’re already strength training
‘Running twice a day means you’re going to run more mileage, which means you need to be very durable,’ Bui says.
Research shows that strength training and plyometrics can help build durability. ‘You need to be lifting weights twice a week, at minimum once a week, and you should not sacrifice lifting for running another session,’ Bui says.
Laraia agrees: ‘If you’re not doing strength training minimum once a week, let’s add that before we even think about a double,’ he says. ‘I need you to be strong enough to do 26 miles.’
You have your nutrition dialled in and you’re prepared to eat more
The experts agree that nutrition becomes even more critical for runners adding doubles. ‘I think the biggest mistake in terms of adding doubles is you don’t eat enough throughout the day so your energy levels are going to be low by the time you get out there again,’ Bui says.
Even if you’re not adding mileage (but rather just dividing up existing mileage into two runs a day), your body is in ‘workout mode’ for longer, Laraia says. ‘Your metabolism is going to run a little hotter if you’re doing two runs because it’s not completely coming down.’ Make sure you’re rehydrating and replenishing all your macros in between runs.
You’re on top of recovery, mentally and physically
Recovery also becomes even more crucial for athletes running twice a day, which means getting at least seven to nine hours of sleep becomes even more non-negotiable. But the experts also say to factor in life stress.
‘Some people almost force the double, meaning they’re so busy from their workday, they’re super stressed out, they’re rushing home, they’re skipping their snacks so that they can do the second run, and that’s really not the point,’ Bui says. ‘Make sure that it fits into your lifestyle, your routine, you can recover well from it, and you’re healthy.’
How to Add Doubles to Your Routine
‘My general rule of thumb for life and endurance sports is to gradually introduce new things,’ Bui says. She recommends starting with just one ‘painfully slow’ 30-minute double a week (meaning the second run of the day is 30 minutes) for at least two weeks. ‘If your body’s feeling generally good, you can up that to two doubles a week. Some people go as high as three,’ though three doubles a week works best if you’re already running about 50 miles or more per week.
You’ll know you’ve pushed too hard into doubles if you’re feeling constantly fatigued, have difficulty focusing throughout the day, have trouble sleeping, or can no longer hit paces during workouts, says Bui, as signs of overtraining.
The first run of the day should be your ‘primary’ run, and the other should be your shakeout or ‘flush’ run, Laraia says. But ideally, reserve quality miles like speed sessions for days when you’re just running once and keep both of your doubles day runs easy, particularly your midweek easy runs. ‘You’re just accumulating time on feet,’ Laraia says. (An exception to this rule is double thresholds, or the Norwegian Training Method, which is its own beast.)
Here’s the key to doubles in general: Make sure to allow at least six hours in between your runs, Laraia says. This allows for your muscles and energy systems to recover (along with your mind!). If you start the second workout too soon, ‘your body’s going to be struggling on the second run and your body’s going to go into overload mode versus benefiting,’ he says.
Another tack: ‘One of the things that I dabble with for people that are interested in doubles is looking at an overnight,’ Laraia says. ‘So if you run at night and then wake up and run the next morning, technically you slept and it’s a different day, but it’s only 12 hours between runs, which is kind of like a double.’ Consider it a sort of introduction to running twice a day.
Either way, listening to your body is key. ‘Injury is obviously the biggest [warning sign] for everything,’ Bui says. But also watch out for excessive fatigue, irritability, or soreness that doesn’t go away within 48 hours.