Singles Vs. Doubles: What Would Happen?
This question has been bothering me lately…
Is it better to run your miles all at once or split them up?
Training dogma (and perhaps common sense) would have you think that fitting your miles in one go would be the best way to gain that aerobic adaptation that we are searching for.
However, there has been an increasing amount of evidence — both experimental and empirical — that splitting those miles has no effect on your aerobic system’s development and can in fact aid in recovery.
The reason that your body can still make the same aerobic adaptations has to do with glycogen depletion and cumulative fatigue as you advance in your training cycle — in simpler terms your body is already in a depleted state at the start of your second run so the break in between runs still allows you to gain fitness because the same enzymes are triggered as with singles.
Ok maybe that wasn’t a simpler explanation but the point is whether you are running singles or doubles you are still gaining the aerobic fitness that you are looking for during an easy run.
Now, lets move on to the pros and cons of each:
Weekly Mileage In Single Runs
My high school coach was old school in a lot of aspects — how you ran your mileage was one of those. Running twice a day to him was out of the question because it just made it easier on you, and although I detailed earlier about how that isn’t necessarily the case… he might have been onto something else. I’m talking about the mental aspect (something we don’t think about as much as we should) — mentally running becomes tougher the longer you are running, so doing your miles all in one is better for developing that mental strength associated with grinding it out.
The cons to this approach come in the form of fatigue and an overall higher demand on you body and mind. Something that these shorter runs do is allow your body to release more growth hormone and allow you mind to recover in between runs. This can be a huge deal in your training!
Depending on your body type and how you respond to mileage doing all of your runs at once might not be the best option for your recovery and overall wellbeing. This approach may lend to you being worn down and not recovering to the best of your ability at the end of a training cycle.
Weekly Mileage In Doubles
We already discussed a few of the benefits of running doubles over singles — but I want to dive further into how our body releases growth hormone in response to running. Growth hormone is extremely important in recovery, there is a huge spike in production over the first 30–40 minutes and then it kind of levels off from there with production rate decreasing from there (think bell curve). So if your goal is to optimize recovery than it would be logical to think that a 30–40 minute run in the morning and a 30–40 minute run in the evening would allow your body to recover more than if you ran 70–80 minutes straight.
The cons to doubling come in the mental aspect again and depending on the race you are training for — you would have to accommodate for that. In marathon and half marathon training, mentality can be a make or break in both your training cycle and in the race itself which is the goal!
Time would be another con, in Running With The Buffaloes University of Colorado coach Mark Wetmore talks about all of his “student-athletes” run singles because they had limited time to fit a run in. If you are a professional, you can run in the morning and evening however I do understand that it can be tough to schedule. On the flip side if you only have 50 minutes in the morning before work and 30 minutes in the evening before you have to put the kids to bed — doubles are a good way to keep up with your plan.
Optimize your schedule!
My Take
Ultimately it comes down to what works best for your body and your schedule.
With singles and doubles I think we can periodize them and eventually have a pretty good mix throughout the week — So in a base building phase I would prefer mostly singles but with a double mixed in to help with recovery and keep you fresh. Then, as the program progresses — eventually the only longer days would be the long run and then a medium long run. The rest of the week would have doubles mixed in — I think this would help you stay fresh as the program progresses but you would still reap the benefits of grinding through the miles in the buildup phase of your program.
That’s my take, what’s yours?
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-Justin
