A high step count does not tell you whether your aerobic system was trained. The LFS standard for easy aerobic work, often called Zone 2, is three sessions a week of at least 30 continuous minutes at a conversational pace: full sentences, but you could not sing. Shorter sessions, or ones that drift harder, do not count.
Many of the people I coach hit 9,000 to 11,000 steps a day. They are proud of it, and they should be. It beats sitting.
But a step count tells you how much you moved. It says almost nothing about whether your heart and working muscles spent any sustained time doing the work that builds aerobic capacity. Steps come in pieces: a trip to the car, a lap of the office, the walk to a meeting. Easy aerobic training is one continuous block, held long enough and steady enough to ask the body for an adaptation.
I call that kind of input a signal, in the physiological sense: something strong enough and long enough to tell the body to change. Ten thousand scattered steps rarely add up to one.
What Has To Happen Each Week
Three sessions a week. At least 30 minutes each, ideally 30 to 45. Conversational pace the whole way: you can speak in full sentences without gasping, but you could not sing.
Walking uphill counts. So does cycling, rowing, the elliptical or an easy jog. Any of them can work, and any of them can miss. What decides it is the pace you hold and how long you hold it.
A 20-minute session does not count toward the three. Neither does a session that started easy and finished as a hard workout.
Why This Matters After 40
For most professionals over 40, the problem is not effort. When they train, they train hard. What gets skipped is the easy, steady, unglamorous work underneath the hard sessions, because it does not feel like it is doing anything.
That base is what you draw on in ordinary life: a full day on your feet in a new city, a long hike, three flights of stairs without stopping at the top. It also supports the harder training. Near-maximum intervals are short. The hours between them are aerobic.
What the Research Shows
The thinking behind easy aerobic work comes from how muscle chooses its fuel. At easy effort, working muscle relies more on fat. As effort rises, it leans more on carbohydrate, and lactate starts to build up in the blood. The aim of this kind of session is to spend sustained time on the easy side of that shift.
One study measured this in three very different groups: professional endurance athletes, moderately active people, and people with metabolic syndrome (San-Millán & Brooks, 2018). Each person exercised at rising intensities while the researchers measured blood lactate and how much fat and carbohydrate they were burning. Across all three groups, the pattern was consistent: as lactate rose, fat burning fell and carbohydrate burning rose.
The authors point out that lactate and fat are both fuels handled by the mitochondria, the energy-producing structures inside muscle cells. So measuring the two together gives an indirect read on how well a person’s muscle can switch between fuels and use oxygen.
The limits matter. This was a comparison of groups at one point in time. It shows how fuel use and lactate relate across people with very different fitness. It did not test a training program, and it does not say how many sessions a week to do.
Where the Number Comes From
I want to be plain about the dose. I know of no study that tested three sessions of 30 to 45 minutes a week in adults over 40 and found it to be the right amount. Three sessions is the LFS standard, set from years of coaching and from what this work asks of the body.
You may notice it looks lower than the public health guideline of 150 minutes a week of moderate activity. The two numbers measure different things. 150 minutes is a weekly total, and you can reach it in short bouts spread across the week. Three sessions of 30 to 45 minutes describes what has to happen inside a single session. You can clear the weekly total and never once hold 30 continuous minutes at a steady, easy pace. That session is what this standard asks for. More easy work on top of the three is welcome.
How You Know It Counted
- You passed the talk test for the whole session, not just the first ten minutes.
- If you wear a heart rate monitor, you stayed below roughly 70 percent of your maximum.
- You logged it, and it ran 30 minutes or longer.
How It Gets Missed
- Counted as steps. A busy day on your feet feels like it should count. Unless it held a continuous 30-minute block at a steady pace, it did not.
- Drift. The pace creeps up. By minute 12 you are breathing too hard to talk, and the session has become a moderately hard workout.
- Shortened. Twenty minutes on the bike after lifting, logged as cardio.
- Stacked after heavy strength work. On tired legs, a steady easy pace is harder to hold, and the session tends to drift or get cut.
- Skipped because it feels too easy. Easy is the assignment.
Where to Start
Pick an activity you already do. Slow it down until you could narrate what you are doing, out loud, in full sentences. Hold that pace for 30 minutes. Around minute ten you will want to speed up. Hold the pace anyway.
Build frequency first: one session in the first week, two in the second, then three. If you have heart, joint or balance concerns, talk to your physician before you start.
What to Do This Week
- Schedule easy aerobic sessions of at least 30 continuous minutes on an activity you already do: walking uphill, cycling, rowing or an easy jog. If three is a jump, do one this week and add one each week until you reach three.
- Run the talk test for the whole session: full sentences, no gasping, no singing. If you wear a heart rate monitor, stay below roughly 70 percent of your max.
- Log each session's length. Anything under 30 minutes, or anything that drifted into hard breathing, does not count toward the three.
Sources
- San-Millán I, Brooks GA. (2018). Assessment of Metabolic Flexibility by Means of Measuring Blood Lactate, Fat, and Carbohydrate Oxidation Responses to Exercise in Professional Endurance Athletes and Less-Fit Individuals. Sports Medicine, 48(2), 467-479. doi:10.1007/s40279-017-0751-x PMID 28623613.
Client stories may combine details from more than one person, with identifying details changed for privacy. This article is educational and is not medical advice.
Also published in Built to Endure, our free weekly publication.