Intro to Triathlons Pt. 1: Why Should You Try One After Your Marathon?
So you ran a marathon… now what? A triathlon might just be the answer to your question!
If you just ran a marathon, you probably know this emotional rollercoaster: for a week you feel unstoppable and like a completely new person, and then, suddenly, you’re in that weird post-race slump of “okay, now what do I do with my life?” The post-race blues are a real thing and can throw a wrench into your day-to-day life. This is where triathlon sneaks in as a pretty perfect “next chapter” for runners.
Last year after the San Francisco Marathon, we gave you a quick “What now?” run-down that included a suggestion to try a tri. Today, we’re back with a more detailed how-to about your triathlon journey.
During a triathlon, you still get the endurance buzz. You still get a very well-earned finish line. But you also get variety, new skills to learn, and way less mental grind than locking into another run-heavy cycle would require.
In this guide, I’ll break down what a triathlon actually is, why marathoners tend to love it, which distance makes the most sense first, and next week, we’ll look into how to train without feeling like you’re starting from zero.
Triathlon 101 (in plain English)
A triathlon is three sports done back-to-back, timed from start to finish. First you swim, then you hop on a bike, and then you take whatever is left in the tank an run. Yes, it’s all in one go, with the clock running the whole time.
What race day feels like
Most races use wave starts (groups going off by age or category), which you’ll likely be somewhat familiar with if you’ve run any bigger marathon, or a rolling start (you line up and shuffle into the water a few at a time). Then you swim, run into a transition area, bike, come back, transition again, and run to the finish.
You do not need to be elite (or rich)
You don’t need a $7,000 bike or an aero helmet or a pro background. For your first tri, you mainly need basic swim gear, a safe bike, a helmet, and a willingness to learn a few new things.
Quick tri vocabulary lesson
- T1 / T2: Transitions. T1 is swim-to-bike, T2 is bike-to-run.
- Brick workout: A bike ride followed immediately by a run (even a short one).
- Drafting rules: In most beginner-friendly triathlons, you can’t ride close behind someone to “hide” from the wind. (Some races allow drafting, but assume non-drafting unless told otherwise.)
- Tri suit: A one-piece or two-piece outfit you can swim, bike, and run in. Nice, but mostly not required.
Why triathlon is a great next chapter after a marathon
1) Fresh motivation (and new skill curve)
Running improvement can get slow after you’ve done the marathon thing for a while. Triathlon gives you a new learning curve, especially with swimming, and that makes training feel interesting again. Progress comes fast at the start, which is super motivating. (For my ultra, my coach prescribed biking and swimming as cross-training. Seeing rapid improvement in either kept me motivated for my runs, especially when I couldn’t see tangible improvement in my running.)
2) Lower impact without losing fitness
After a marathon, your body just went through a lot. Triathlon lets you keep building aerobic fitness while reducing the repetitive pavement pounding and the impact of high run mileage. Swimming and biking are easier on joints and tendons, which is a big deal if your marathon build left you a little creaky. (Again, I basically did something of a running-heavy tri training for my ultramarathon. It helped my body keep it together and stay healthy when my collective weekly distance went to 200 km/week.)
3) You become a more complete athlete
- Cycling builds aerobic volume and leg strength without the same impact cost, making it a great form of cardiovascular exercise.
- Swimming improves breathing control, posture, and overall body awareness (it can also be humbling, in a good way). Integrating swimming into your training can yield even better results.
When you train for a triathlon, you end up fitter and stronger in addition to being good at running far.
Usual triathlon distances
There are a few different tri distances that you can do. Some people will start with a Sprint or Olympic triathlon, some will go to Half or Full Ironman (possibly the most popular triathlon races around the globe).
Sprint
- Swim: 740m
- Bike: 20k
- Run: 5k
What it feels like: Do you still remember your first 5k? It was hard and fast and even though it felt endless, it was over before you really got into it. That’s the Sprint, and it’s a great way to figure out whether you’re good at combining three sports into one in a race setting.
Olympic triathlon
- Swim: 1500m
- Bike: 40k
- Run: 10k
What it feels like: This is the “real triathlon” distance for a lot of people. Still manageable, but you’ll want a bit more bike endurance and swim confidence. It’s a great goal if you want a challenge without turning training into a part-time job.
70.3 (Half Ironman)
- Swim: 1.9k
- Bike: 90k
- Run: 21.1k (half marathon)
What it feels like: Totally doable for marathoners after you learn fueling and long-ride durability. The bike is the big commitment. You can’t fake 90k if you haven’t spent time in the saddle.
Full Ironman
- Swim: 3.8k
- Bike: 180k
- Run: 42.2k
What it feels like: This is not the “next step” for most people right after a marathon. The volume, cost, logistics, and burnout risk are real. It’s a whole lifestyle block.
How to choose your first one
You’ll need to be honest with yourself. Pick based on your time availability, swim comfort, injury history, and your “why” (trying something new vs chasing a huge badge). If your goal is “have fun and get addicted,” start with Sprint or Olympic.
Triathlon is a logistics sport
This might be the biggest shift for you. Running by itself rewards endurance. For a triathlon, you’ll need endurance plus some good logistical skills. You’re managing gear for three sports, two transitions, and pacing across three legs. That might be the hardest one; to pace yourself well across three very different sports. Fueling also starts early and matters a lot.
Transitions are the “fourth discipline”
The good news is that if you manage your logistics well, especially as a beginner, you can grab a ton of “free speed” just by not panicking in transition. If you can calmly put on a helmet, find your bike, and not forget your shoes, you’re ahead of a lot of people doing a tri for their first time.
Pacing is the crux of the race
The bike is where many marathoners get tricked. It can feel easy to pump the pedals, especially early on. But triathlon is like going out way too fast in a marathon. You can do it, but you’ll pay later. The goal is to ride strong while keeping your legs usable for the run. What that means for you, you’ll need to figure out in training.
What carries over from marathon training
You’re not starting from scratch. As a runner, you already have a huge advantage.
- Aerobic base: You can already handle endurance without burning out.
- Mental toughness: You know how to stay calm and work through discomfort.
- Pacing discipline: You know how to hold back, even if you sometimes ignore it.
- Fueling basics: You already know how to manage your carbs and hydration, and you’re likely not just winging it.
- Training structure: Easy days, long days, workouts, recovery. You’re not new to the process.
What won’t carry over
There are a few things you’ll likely be completely new to when it comes to triathlons. (After all, that might be why you’re doing it.) Here are the skills you likely won’t have at the ready from your marathon training.
Swimming is the wildcard
In swimming, technique can matter more than fitness. You can be marathon-fit and still feel cooked after 200 meters if you’re tense and fighting the water.
The biggest barriers are usually breathing control, being comfortable with your face in the water, and staying relaxed when your heart rate spikes.
Biking is its own kind of hard
Bike nutrition can make or break your race
You can eat more on the bike than you can while running. That’s a big advantage, but only if you train it. Good bike fueling can make the run leg way more enjoyable and, quite literally, reward you in the long run.
Open-water nerves are normal
Low visibility, crowds, contact, getting bumped, swimming “off line.” It’s a lot at first. The fix is gradual exposure and choosing a beginner-friendly swim setting for race one.
Next Week: The HOW of triathlons
We’ll stop here today now that we’ve talked about why you should try a tri. Let it marinate for a bit and come back next week (once you’ve decided that you absolutely need to try one) for the HOW of going from marathons (or running in general) to triathlon training!