Bike/Run Balance and Discipline Specific Training Blocks

Athletes many times begin their triathlon career and preparation coming from swim, bike or running backgrounds.  This type of a background lends itself to training like a swimmer, biker, or runner versus like a triathlete.  Those athletes that don’t come from this type of a background many times seek to immerse themselves into the world of one, or all of these single sports in an effort to improve their triathlon pro-ness. In this writing, I discuss the use of single sport focus blocks as well as the delicate balance between bike and run stress in any triathlon preparation program.

The most common area I see athletes applying focus blocks is are those that may have run limiters.  Many times they really focus, and in some cases over focusing on their run training volume or run training stress. Although bigger run miles can lead to better running, that doesn’t always lead to faster run times off of the bike in triathlon. How does one know what the correct balance between bike and run training stress for the sport of triathlon?

If you are an athlete that is training for a non-draft triathlon (IRONMAN or 70.3), I never like to see the run volume on a weekly basis much more than a 1/5 of the bike volume in miles. That is, if the bike mileage is 200 per week, we shouldn’t see the run mileage beyond 40 miles per week. This rule of thumb applies where bike training mileage is below 450 in IRONMAN, and 275 in 70.3 (almost everyone!). What this rule of thumb attempts to do is ensure that the athlete has the bike durability required to use their run fitness/strength after a 56 mile or 112 mile bike ride. Although run mileages that exceed this rule may improve open run times, this improvement will likely be negated (and in many cases reduced further) in triathlon running due to the significant impact that the bike ride will have on the athlete – they are simply not in a position to run well off the bike due to reduced bike durability/fitness.

So how does one go about improving their off the bike run times if they can’t increase run volume beyond 1/5 of bike volume? First off, we look at what their “decouple” is…..meaning how much slower they run a 10k, or half marathon off the bike versus during an open road race. Assuming there is no nutrition limiters, and the bike is executed (paced) in a reasonable way, we look for less than 6 percent in 70.3 and less than 12 percent in IRONMAN (this percentage about doubles when you double the race distance). That is, if you run a 1:40 open half marathon, we shouldn’t see 70.3 run splits of slower than 1:46. If we do, than there is likely a lack of bike durability and good running off the bike will come with more bike miles. If the de-couple is less than this, than it’s their open running ability that’s limiting them. In this case, if they have already been running at 1/5 bike volume, we may start to consider a run focused block of 3-4 months where we really focus on the running mileage/stress at the reduction in stress from the bike.  This run focus block would typically culminate in a run race – like a marathon to fully immerse the athlete in that culture. During this block the athlete goes well below the 1/5 rule of thumb to improve open run times, and then goes back to a more balanced triathlon preparation program as they prepare for their next triathlon. The key is to not go beyond the 1/5 rule of thumb while in direct preparation for a triathlon, since any improvements in open run times will likely not translate to improvements in off the bike running due to lack of bike durability – the athlete is simply not in a position to run well when they get their feet on the ground.  This situation many times also translates to slower bike splits given the well-known “pounding” the legs take with large run mileage.  Both of these issues intuitively mean that any run focused period should be kept at least 16-20 weeks out from a major goal triathlon race.  This approach will insure that there is enough time to apply bike stress under a more balanced triathlon program before a big race where the new running speed can be adapted to great running speed off the bike.

Swim focus blocks should be treated similar to run focus blocks and kept about 16-20 weeks out from race day, to insure enough time to build the important lower body durability that comes with cycling and running.  Cycling focus blocks on the other hand can be used a bit more liberally as the cycling stress applies to improving about 50% of triathlon, and also has significant cross over to running well off the bike.  Athletes who decide to apply a focused block of cycling should keep those periods at least 8-12 weeks from major goal triathlon races.  In most cases this period leaves enough time to safely increase run stress to that required for the race distance.

Incorrectly used single sport focus periods are a simple but common mistake for many triathletes. Manipulating training volume is one of the most powerful tools we have as athletes and coaches and the balance of bike/run stress is particularly important and should be approached VERY carefully.