Cardio is more than Cardio: What to train for Healthy Aging

Oct 5

8 min read

A common question I get is, "How much cardio should I be doing?" The internet hasn't made it easier. One source says Zone 2 is everything, another says only HIIT matters, and your watch says you hit your steps. So I'd to ask a better question: what are you actually trying to train? You may not need more cardio. You need to know what each kind is doing for you.

Why Cardiovascular Fitness Matters for Longevity

Cardiorespiratory fitness is how well your heart, lungs, blood vessels and muscles work together to take in and use oxygen. It's one of the strongest health markers we have. A 2024 overview in the British Journal of Sports Medicine, covering 199 studies and more than 20 million observations, found that people with high fitness had roughly half the risk of early death compared with people with low fitness. They also had lower rates of several chronic diseases, especially heart failure.

One caution: these are observational studies, and fitter people differ from less fit people in lots of ways. The evidence strongly suggests fitness matters, but it doesn't prove that raising your fitness by a set amount adds a set number of years. It's a very good reason to train, not a guarantee.

The most common measure is VO2 max, the most oxygen your body can use during all-out effort. Think of it as the size of your engine. It declines with age, and that decline speeds up. A long-running U.S. study found losses of about 3 to 6% per decade in your 20s and 30s, rising to more than 20% per decade in your 70s, even among active people. The good news is that it stays trainable. Aerobic training reliably improves fitness in older adults, and the people who start lowest often gain the most.

Cardio Isn't One Thing

First, a distinction that matters: physical activity is moving more and sitting less (ie walking the dog, gardening, taking the stairs.) Cardiovascular training is deliberately challenging your heart and lungs enough to drive a specific adaptation.

Both matter. They just aren't the same thing. And within training, different intensities build different parts of the engine.

The Different Intensities, Explained

Easy aerobic (often called "Zone 2"). This builds your foundation: more tiny blood vessels in your muscles, more mitochondria (the cell's energy factories), a heart that pumps more blood per beat, and better use of fat as fuel. "Zone 2" usually means the pace just below the point where breathing starts to pick up noticeably. But zone systems aren't standardized. Some

use three zones, some five, some seven, and age-based heart rate formulas can be off by a lot for any one person. That's why the talk test (you can speak in full sentences) and effort on a 1 to 10 scale are just as useful as a heart rate monitor.

What's overstated? A 2025 review in Sports Medicine found little evidence that Zone 2 is uniquely best for improving mitochondria or VO2 max in everyday exercisers. Harder work often does as well or better, minute for minute. Easy aerobic work is valuable because it's sustainable, repeatable and easy to recover from. It isn't magic.

Tempo. Comfortably hard, short phrases only. It builds your ability to hold a strong, steady pace, like a long climb on the bike.

Threshold. Harder still, near the top of what you can sustain, usually in blocks of 8 to 20 minutes. It raises the pace you can hold before fatigue builds fast.

VO2 max intervals. Hard efforts of roughly 2 to 5 minutes, repeated a few times. Why that length? It takes a minute or two for your oxygen use to climb near its ceiling, so the interval needs to be long enough to spend real time there, but short enough to repeat. The recovery between efforts (often 2 to 4 minutes, easy) is what lets each rep be high quality instead of a slow fade.

Sprints. Truly all-out, about 10 to 30 seconds, with long recovery (often 2 to 4 minutes or more). These aren't just shorter VO2 max intervals. A short sprint relies mostly on your fast, immediate energy systems and trains power and speed. A 3-minute hard interval is limited mainly by how fast you can deliver and use oxygen. Different stress, different adaptation.

Cardio Training Cheat Sheet

Boundaries between these categories are approximate. Different systems draw the lines in different places.

Type	What It Trains	What It Feels Like	Typical Duration	Example
Easy aerobic / endurance	Aerobic base, capillaries, mitochondria, fat use	RPE 3–4/10. Full sentences.	30–90+ min	Brisk walk, easy bike ride, steady hike
Tempo / moderate-hard	Sustained strong pace	RPE 5–6. Short phrases.	15–40 min	Steady uphill hike, rolling bike ride
Threshold	Pace you can hold before fatigue spikes	RPE 7. A few words at a time.	2–3 blocks of 8–20 min	3 x 10 min hard, 3 min easy
VO2 max intervals	Top-end aerobic capacity	RPE 8–9. Talking isn't happening.	2–5 min efforts, 4–6 reps	4 x 3 min hard uphill, 3 min easy
Sprints	Speed, power, anaerobic capacity	All-out.	10–30 sec, long rests	6 x 20 sec bike sprints, 3 min easy

Myth Buster

MYTH: "If I'm active and get plenty of steps, I don't need cardio training."

Daily movement is enormously valuable. A 2022 analysis of 15 studies found that in adults over 60, the lower mortality risk linked to more steps leveled off around 6,000 to 8,000 a day. But being active isn't automatically the same as training your fitness. If most of your steps are easy, your engine may not have a strong reason to grow. Keep the steps, and add some purposeful effort too.

MYTH: "If cardio is good, harder cardio must be better."

Not necessarily. The Generation 100 trial followed about 1,500 Norwegians aged 70 to 77 for five years. The group doing twice-weekly intervals had the lowest death rate, but the difference wasn't statistically conclusive, and the control group (following standard activity guidelines) did well too. Intensity is a useful tool, but consistency matters more. Hard sessions also need recovery, and easy aerobic work is what lets you train hard on the days that count.

Does My Hiking, Walking or Strength Training Count?

Walking: It depends. For someone newer to exercise, a brisk walk or steep hill can be real training. For a fit hiker, a flat stroll is valuable activity but probably not a training stimulus. Pace, terrain and your fitness level decide.

Hiking, biking, skiing, pickleball: Count them by actual intensity. A long climb to a ridge might be two hours of tempo with some threshold mixed in. A mellow groomer day is mostly easy. Pickleball is stop-and-go, closer to repeated short bursts.

Strength training: Yes, it helps. A 2022 meta-analysis found resistance training modestly improved fitness in healthy older adults. But being out of breath during a circuit is different from sustained aerobic work. Often your legs tire before your heart and lungs are fully challenged. Strength training is essential. It just doesn't replace cardio.

What Should My Week Actually Look Like?

Here's one example for a healthy, active adult of roughly 45 to 70 who strength trains. It's a starting point, not a prescription.

2–3 strength sessions
2 or more easy aerobic sessions of 30–60 minutes: brisk walks, bike rides, hikes
Occasional harder work, maybe once a week or every other week: tempo, threshold or a short set of intervals
Daily movement throughout the week
Recreational days counted honestly. A hard 4-hour hike or big ski day may already be your hard cardio session for the week. Don't stack intervals on top of it just to check a box.

Build training around your total activity and recovery. From your 50s on, recovery takes a bit longer, so keep hard cardio and heavy leg days apart when you can. Sleeping poorly or legs feel heavy? Make it an easy day. If you have heart disease, symptoms like chest pain, or you're new to vigorous exercise, talk with your doctor before adding hard intervals.

Try It: Choose Your Cardio

Want to feel the difference between intensities? Pick one of these per session. They train different things, so they aren't interchangeable. Warm up for 5 to 10 minutes first, starting easy and building gradually. Bikes, inclines and hills are easier on the joints than flat running for the harder options.

Option 1: Build Your Base (20–25 minutes). Continuous brisk walking, hiking, cycling or rowing at RPE 3–4, a pace where you could hold a full conversation. You should finish feeling like you could keep going. Easier: 10–15 minutes on flat ground. Harder: add hills or go 45 minutes or longer.

Option 2: Challenge Your Ceiling (about 30 minutes with warm-up). 4 rounds of 3 minutes hard (RPE 8) and 3 minutes easy, then a 5-minute cool-down. By the end of each hard effort you can only get out a word or two, but your last rep should look like your first. Easier: 3 rounds of 2 minutes hard, 2 minutes easy. Harder: 5 rounds, or 4-minute efforts.

Option 3: Short + Fast (about 20 minutes with warm-up). 6 rounds of 15–20 seconds fast and hard (RPE 9), with 2–3 minutes very easy between, then a 5-minute cool-down. A stationary bike or uphill walk works well. Every effort should feel sharp because you're fully recovered. Easier: 4 rounds of 10 seconds, fast but not all-out. Harder: build to 8 rounds. Best for people who already train regularly without joint issues.

Most weeks, Option 1 should show up most often. Save Options 2 and 3 for days when you feel fresh, once a week or less.

Strong and Fit: You Want Both

Strength training is the foundation of how we coach at MTN Life Fitness, and our classes stay primarily strength-focused. Some workouts will get your heart rate up, but that's a bonus, not a replacement for your walks, rides and hikes.

Longevity asks for several things at once: strength, muscle, power, balance, mobility and cardiorespiratory fitness. You don't have to choose between being strong and having a good engine. The goal is both.

Bottom Line

Walking, hiking, intervals and sprints all train your cardiovascular system, but they don't train it the same way. Build a base with easy aerobic work, add harder efforts when you're recovered, count your mountain days honestly, and keep lifting. You don't need to do more. You need to know what you're doing it for.

Curious where your fitness stands before ski season? MTN Life Fitness offers ski fitness assessments in Park City. Book your assessment HERE.

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Sources & Further Reading

Lang JJ, et al. Cardiorespiratory fitness is a strong and consistent predictor of morbidity and mortality among adults: an overview of meta-analyses. British Journal of Sports Medicine, 2024.
Fleg JL, et al. Accelerated longitudinal decline of aerobic capacity in healthy older adults. Circulation, 2005.
Stensvold D, et al. Effect of exercise training for five years on all cause mortality in older adults: the Generation 100 study. BMJ, 2020.
Storoschuk KL, et al. Much Ado About Zone 2: A Narrative Review Assessing the Efficacy of Zone 2 Training for Improving Mitochondrial Capacity and Cardiorespiratory Fitness in the General Population. Sports Medicine, 2025.
What Is "Zone 2 Training"?: Experts' Viewpoint on Definition, Training Methods, and Expected Adaptations. International Journal of Sports Physiology and Performance, 2025.
Paluch AE, et al. Daily steps and all-cause mortality: a meta-analysis of 15 international cohorts. Lancet Public Health, 2022.
Smart TFF, et al. The role of resistance exercise training for improving cardiorespiratory fitness in healthy older adults: a systematic review and meta-analysis. Age and Ageing, 2022.
U.S. Department of Health and Human Services. Physical Activity Guidelines for Americans, 2nd Edition. 2018.