Training for half marathon while racing

I’m contemplating trying to run a half marathon in about 7 months (about 2 months after my cycling racing ends). I don’t run much or at all currently. For cycling I’m competing most weekends and averaging about 450-500 TSS per week, with some weeks peaking above 650 TSS.

  1. How much will running compromise my cycling and specifically my racing (cycling is my priority)
  2. How can I ease into running gradually to build mileage? Can I backload the running as the racing season winds down? How so?

What are your goals for the half? If your only looking to complete it, you could pretty easily do that with 8 weeks of running. If you are looking to go fast, you’ll want to build up mileage to get a decent base, then Add speed work once a week once your race season is over.

Since it’s my first, my goal is just to finish.

I would start early, but only 1-2 runs per week, both easy, one short(ish) 45-60 mins, the other starting the same but stretching gradually towards 80-90 mins. That will give you a base without hindering the bike. Then for the last 8 weeks, add in speed work as suggested above.

If you have good fitness and isn’t overweight or something that could harm your joints, 2 months should be enough to get ready for a half marathon so, if cycling is your priority i wouldn’t worry with running before the end of the season.

If you dont have a history of running be careful. Aerobically you’ll be very fit but your muscle / joints won’t be conditioned to the impact.

It’ll be very easy to push too hard and get injured.

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Thank you all for all the advice. I think I’ll start with 2 runs per week about 20-30 min each (2-3 miles) for the first couple of weeks and then gradually ramp it up to 10-12 miles per week as the season winds down. Then come August I can focus on running with a goal of doing the half in late October/November. As someone pointed out, I have the aerobic fitness, the challenge is the different joints and pounding that I’d be taking. By ramping slowly, I’ll hopefully avoid that problem. Thanks again.


The (slow!) runs now will help develop the joints and muscular endurance specific to running. Slow is the word. The general consensus is to limit easy runs at 75-78% of max HR.

@chad has tri plan that include swim and run, try to use one of the plan and delete the swim/rides keeping only the run parts.

@UKCarl is spot on with his comments IMO.

Be really careful, I’ve known a good number of very good cyclists who start running and they are far to fit for their own good! They have the cardiac ability to run fast but haven’t built up the joint and ligament strength and durability that only comes with a good amount of running.

It’ll almost certainly feel very easy but build up time and distance slower than you think you should.

No offense, but don’t do this. One should not have their first few runs be this long. Run for like 15 minutes to get your joints used to it. Then ramp up the time after your bike race.

Depends on the running background and experience of the person, of course. Someone who has not run regularly in years, you are correct. Someone with quite some mileage, starting at 45 minutes is no issue.

I started training in December for a 70.3 this august and had next to no running base. I’ve had pretty good success (no injuries, increasing miles and pace) following the BarryP plan. It gets you running more often with 3 short runs, 2 medium runs, and 1 long each week all at easy pace, which for me falls between 135-145hr. I started at about 10 miles a week and I’m now averaging 20-25.

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