When Cycling Is Better Than Another Run

50-70% of my aerobic training each week happens on a bike.

That was true when I ran my 16:56 5K, too. I was running less than 25 miles per week and doing most of my easy aerobic work on the bike.

It was even more lopsided when I started.

For my first 6 months of running, I ran 1-2 days a week, 3-8 miles total, and rode 2-3 hours a week at around 115 bpm (60% of running max HR).

My 5K went from 20:35 to the mid-17s running less than 15 miles a week.

The running sessions had a specific job and the bike gave me another (much less stressful) way to build aerobic fitness between them.

For me, that made it easier to train consistently while limiting how much running impact my (then) ~27 BMI body was taking.

What is the extra session supposed to accomplish?

Before you add another run, ask yourself that question.

Run
If you need more practice running, more time on your feet for a race, or a specific running workout.

Ride
If you want more easy aerobic work and your legs are already carrying fatigue from running and lifting.

That distinction matters when you're trying to fit everything into a normal week.

You might already have a couple of useful running sessions and a couple of lifting days. Adding more work only helps if you can keep doing the sessions that drive your progress.

Why the bike works so well

I can't stress this enough: compared to running, easy biking is an incredibly useful way to add additional aerobic training with very little stress on the body.

Plus, a stationary bike requires zero skill.

Running is high-impact. Every step is a mini collision with the ground, landing at roughly 2-3x your bodyweight. At 200 lbs, that's 400-600 lbs going through your legs thousands of times per run.

The bike has zero impact. It still trains your heart, lungs, and legs, but the recovery cost is a fraction of what running costs you.

You can do 45-90 minutes of easy riding and barely feel it the next day. It won't affect your lifting or your running. Try doing that as a run, especially if you're a heavier athlete, and I promise you'll be feeling it on leg day.

It's particularly useful if you're new to running, lift heavy, and/or are a heavier runner (even if lean!). Your heart and lungs adapt faster than your tendons and joints, so the bike lets you keep building aerobic fitness while the rest of your body catches up.

Plus, it's a great way to get some work in, read a book, or watch your favorite show.

You still need to run

The bike doesn't replace running. If you want to get better at running, you need to run, and you should be building your mileage over time.

It's just not a good idea to increase your mileage too fast at the start, but without more volume, your aerobic gains will be slow.

That's where the bike comes in.

Early on, the bike is how you get extra aerobic volume and speed up your progress.

Here's how it might go:

As your legs get used to running, more of your aerobic work can come from running and less from the bike. (Or you can just keep increasing both 😂).

Keep the easy ride easy

This is where people go wrong.

They get on the bike for an easy session, get bored, and start turning it into intervals.

Now they've added another hard workout.

If I'm using the bike for easy aerobic work, I keep it comfortable. I should be able to talk very easily and finish with plenty left.

When I use my stationary bike at home, I work the entire time. I have a "bike" desk that I put my computer on.

I stay around 115-125 on the bike, and it feels so easy it feels pointless. For comparison, I generally target 125-135 on easy runs (MHR is 190 running).

I also don't try to convert bike miles into running miles. I think about the time, effort, and purpose of the session.

Easy ride cheat sheet
Effort: If you can't fully focus on work or read a book, you are going too hard.

Heart rate: Expect 5-15 beats per minute lower than running. A good starting point is to drop 10 beats per minute off your max heart rate and all your zones. If your easy runs top out around 145, your easy rides should top out around 135.

Time: Ideally, 1.5-2x the time you'd give an easy run. A 30-minute easy run is about 45-60 minutes on the bike. But a 30-minute ride still improves your fitness.

Frequency: 1-3 rides a week, depending on how much you're running.

Capacity Training

I built Capacity Training so you can add cross-training like biking, rowing or walking, or switch a run to an indoor bike. Every workout gets a load score, lifting and cross-training included.

Run faster. Get stronger. capacitytraining.app

Mike