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How and why are back to back runs beneficial

One of the big questions in running training: should you split your daily mileage into two, or should it all be done in one go?

To double or not to double, that is the question.

For many people this might sound silly—why wouldn’t you just do it all at once? But for others, doubles are actually a key way to make their training work around their lifestyle, especially when the ultra-bug bites and marathons start counting as a warm-up run!

So, without further ado, why run doubles?

The Positives

-> More fun

Believe it or not, there are some strange people out there who actually want to run more! In all seriousness though, running doubles is a great way to get in more of what we runners love best: running!

-> Convenience

I think this is probably the big one for most of us non-elites. However carefully we research and plan training schedules, if they don’t fit with our lives then they ain’t gonna happen! Doubles are a useful way of getting in training miles that would otherwise be impossible. It might be that the only way you can get your training done is by splitting it into an early morning session before work plus a half hour in your lunch break.

-> Recovery

In many situations, a little active recovery is actually proven to be more effective than complete rest. It gets the blood flowing, speeding up removal of waste metabolites and stimulating faster repair of micro-tears in the muscles. As far as we notice it, it helps to get rid of that delayed-onset-muscle-soreness (DOMS) faster. Running an additional recovery run in the day can be a great way to get your body on the right track to recovery. But, and it’s a big but, it has to be recovery. And that’s likely to be a lot slower than you might think. You should feel more energised after the run than you did before it, and you shouldn’t be breathing hard at any point. Remember, you’re running to recover, not to get in more miles—distance is irrelevant, just relax and enjoy the movement.

-> Mental and physical preparation for tired legs

For those of you ultra-runners out there, doubles can also be a useful tool to get used to running on tired legs. It isn’t practical to replicate 50 or 100 miles in training; instead, by running twice in the same day, we can replicate the fatigue more safely.

The Negatives

-> Injury and overtraining

Running more leads to more stress on the body and its systems: everything from tendons and muscles to psychology and immunity. It’s as simple as that. If you’re using doubles to get more miles into the training week, you need to be sure your body can handle it. You can’t just add in extra runs without building up to them.

-> Insufficient recovery

The other issue with doubles is that, even if you have built up to the mileages involved, you won’t be getting as much uninterrupted rest as if you were to do the same distance in singles. This is of utmost importance, and you need to make sure that your additional runs are either aiding your recovery, or that you factor in sufficient recovery elsewhere in your weekly schedule. Careful planning of morning versus evening run times can enable clever rest intervals.

-> Wrong training stimulus

Some sessions only generate the desired training effect because of their length. Long runs work by exposing the body to prolonged stress that builds over the course of the workout. The body’s structures and systems can then adapt to this. Long runs also generate a specific form of metabolic training by exhausting muscle glycogen and causing a shift toward fat metabolism. If you were to perform the same distance in two separate runs, that build-up of stress wouldn’t reach the same levels or be as prolonged, nor the metabolic state be the same, and so the desired adaptations wouldn’t occur. The point of the run has been lost.

To some extent this applies to shorter runs too, especially if you’re just beginning or your weekly mileage is low. Think of it this way: if you broke up a 5km run into ten 500m jogs (or even sprints) throughout the day, would it have the same effect? I certainly wouldn’t rate your chances at the next park run!

So, when do you run doubles?

Convenience aside, there are essentially two main ways you’d use doubles. And even if running doubles is just a means to fit running around your lifestyle, it’s worth considering how you run them.

-> For recovery

This is the main way to run twice in a day: one of them (usually the second) should be for recovery. You’ll notice that the elites run doubles all the time, but even they very rarely (if ever) do two high intensity runs in a day. Remember that this run is about recovery—you’ve already given the body a training stimulus earlier in the day, and if you add anything more now then you’re inhibiting the body’s ability to recover and improve.

-> The famous back-to-back(-to-back!)

The exception to the rule. For those training for longer ultras, sometimes we want to generate training stress beyond what is sensible or feasible in a single run. Enter the back-to-back: two long runs without adequate rest between them. Note that this is not the splitting of a long run into two, but rather two long runs in succession. Whether both in the same day, or run in the evening and the following morning, in this case you’re actually trying to offset the recovery from the first run, and instead add additional training stress before your body can recover. This is especially useful for mental training, as well as training the tendons, joints and muscles to deal with the stresses of running and fatigue for extended periods of time. It goes without saying that these should only be approached when you’re sure you’re ready for them, and additional rest must be factored in afterwards.

Thinking of trying it?

Unless you’re already training a significant mileage per week, there isn’t a whole lot of point in running doubles, as you’ll probably get better results by keeping your runs together. But if you are ready for the next step, here are a couple of final thoughts:

Question why you want to run doubles

Remember that doubles can only be effective if they’re run for a reason. In particular, consider the trade-off between stress and recovery. Is this extra run going to help or will it just set me back?—be honest with yourself. Am I using it for recovery or for extra training stress? Or do I just simply want to enjoy more running? All are valid, but consider the trade-offs: there’s no point running twice in a day just for the sake of it.

Introduce doubles slowly

Even if you feel fresher as a result, the stress of each and every mile is still there. Make sure you’re ready for them.

Run by feel

As ultra-coach David Roche puts it: ‘all doubles are optional’. It’s worth remembering. Only run the second run if you’re feeling it, and don’t hesitate to ease back if you need to. Listen to your body.


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