Influencers can’t get enough of Zone 2 low-intensity training. So why did Martin Gibala publish a research paper challenging Zone 2 for the general public? In this episode, Stuart Phillips leads Marty through a critical examination of Zone 2. 

Marty suggests that very little scientific research exists to support Zone 2 training intensity for most people—either as an effective stimulus for cardiorespiratory fitness or mitochondrial capacity. In fact, if you do between three and six hours of cardio a week, Marty believes that Zone 2 isn’t hard enough for you to efficiently accrue training benefits. In other words, if you’re an amateur athlete subscribing to the much-vaunted rule that 80% of your cardio should be in Zone 2, you’re not as fit as you otherwise could be. 

So what is Zone 2 training? And is Zone 2 causing many people to exercise inefficiently, leaving them less healthy than they otherwise might be? What should people be doing INSTEAD of Zone 2? It’s all here, in the latest episode of Exercise Science! 

Have a listener question or an idea for an episode? Email us at realexercisescience@gmail.com

LINKS

Marty and Brendon Gurd’s critical examination of Zone 2: 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

Marty’s coauthor Brendon Gurd on their Zone 2 paper at the Discover Strength podcast. 

Luke Carlson calls the “Much Ado About Zone 2” paper the most important scientific publication of 2025 in this blog post summarizing the paper.  

HIIT and Zone 2: Marty on the Discover Strength podcast

Sperlich paper referenced in this episode: Zone 2 Intensity: A Critical Comparison of Individual Variability in Different Submaximal Exercise Intensity Boundaries

Marty was a coauthor on this ACSM/ESSA position statement on exercise intensities

Marty was senior author on this Sports Medicine paper on exercise intensity in high-intensity activity, which features the intensity diagram Marty mentions

Lifehacker’s Beth Skwarecki notes, Nobody Can Agree On What Zone 2 Is

Oura’s heart rate zones

Whoop band’s heart rate zones

Garmin’s heart rate zones

Peter Attia on Zone 2: This Is How You Know If You’re in Zone 2 When Doing Cardio

More Attia: This is What Zone 2 Training Looks Like

Attia saying 80% of cardio should be Zone 2

Origins of Zone 2: Attia and San Milan in the early days of the trend

Find Stu Phillips on most platforms @mackinprof

Find Martin Gibala on Instagram, which he just joined, @gibalamj 


Exercise Science is powered by EverMe. Download EverMe for free at your favourite App store. 

DISCUSSION POINTS

00:00 Exercise fads

00:34 Intros

02:30 What Zone 2 is

04:21 No uniform definition

06:02 Lactate threshold

08:10 Zone 2 marker variability

09:54 Ventilatory threshold

11:57 Conflation with moderate

12:58 Improving exercise prescriptions

14:40 Health v. performance

16:04 Moderate intensity is better

16:58 80/20 split

18:45 Better alternatives

19:47 Zone 2 origins

20:39 Wearable intensities

22:09 Threshold testing options

23:14 Training for health

24:21 Take-home message

26:05 Vigorous is better

26:44 Listener question

DISCLAIMER

The Exercise Science podcast is for educational and entertainment purposes only and is not a substitute for professional medical advice. Strength training and fitness carry inherent risks. Always consult with a physician or qualified healthcare provider before starting any new exercise program or making changes to your diet. The hosts, producers, sponsors and guests of this podcast disclaim any liability for any injuries or losses connected with the information discussed in this show.

Our co-host Stuart Phillips was the senior author on the ACSM’s gold-standard strength training position statement, a.k.a. “the most comprehensive evidence-based guidance to date on how resistance training supports muscle strength, muscle size (hypertrophy), power, and physical performance across adulthood.” 

In the premiere episode of Exercise Science, co-host Martin Gibala takes Stu through the American College of Sports Medicine update, the first position statement in 17 years. 

Parsing the science, together, Stu and Marty break down why strength is the ultimate compound interest investment for your health span. How important is strength training? Why should you consider strength training 2x per week to be just as important as the other main exercise-related health guideline, 150 minutes of moderate-intensity exercise per week? 

Plus: How much strength training is enough? What’s the minimum that you should do? What changed during the 17 years between position stands? And how did a 1940s bodybuilding doctor rehabbing soldiers pave the way for modern strength training?Forget the oiled-up pumping-iron musclehead stereotype. In 2026, strength training is officially for EVERYONE. And if you’re going to listen to just one podcast about the new guidelines — make it this episode of Exercise Science!

LINKS

Exercise Science is everywhere @realexercisescience: Substack. YouTube. TikTok. Instagram. Apple Podcasts. Spotify. On X you can find us @realexscience. 

Stu is everywhere, too, but mostly on Instagram and X. Follow him on TikTok to make him feel nice!

Marty just started his own Instagram. Give him a follow! He’s also on X!

ACSM Position Stand 2026: The scientific article in Medicine & Science in Sports & Exercise 

Here’s the press release about the stand from the ACSM, and a great succinct infographic summarizing the main takeaways

Here are the two previous ACSM position stands on strength: 2009 and 2002 

Thomas L. DeLorme and the Medical Acceptance Of Progressive Resistance Exercise - Iron Game History

Thomas L. DeLorme and the Science of Progressive Resistance Exercise - Journal of Strength and Conditioning Research (Abstract)

Among the four students on the position stand, Stu said Brad Currier brought the evidence together, did the lion’s share of the writing and herded the cats

All about Ken Cooper, a seminal expert on aerobic fitness who came to understand the importance of strength training 

Honoring the legacy of Steve N. Blair, a giant in the field of exercise epidemiology

Marty and Stu’s MOOC: Hacking Exercise for Health

Exercise Science is produced by Ghost Bureau in Toronto. 

DISCUSSION POINTS

00:00 Marty teases Stu

01:20 Episode outline

02:34 What’s a position stand?

03:36 What is the ACSM?

03:52 Building the team

05:00 What’s new in 2026

06:20 Levels of scientific papers

07:10 2026 v. 2009

08:12 Recommendations

09:30 Effort v. failure

10:38 Volume of training

12:30 Home-based options

14:06 Advice for newbies

15:13 Strength explained

18:57 Power explained

19:37 Why now?

22:17 Weight training for women

23:03 Capt. Thomas L. Delorme

25:36 Circus strongmen

26:30 Outdated philosophies

28:01 Barriers to entry

29:33 No pain, no gain is dead 

31:45 Safety

33:30 Where to start

35:00 Takeaways

35:50 Listener question

36:50 Outro

DISCLAIMER

The Exercise Science podcast is for educational and entertainment purposes only and is not a substitute for professional medical advice. Strength training and fitness carry inherent risks. Always consult with a physician or qualified healthcare provider before starting any new exercise program or making changes to your diet. The hosts, producers, sponsors and guests of this podcast disclaim any liability for any injuries or losses connected with the information discussed in this show.

Kinesiology professor Martin Gibala is the worldwide expert on time-efficient cardio. Kinesiology professor Stuart Phillips is the global expert on strength, muscle development and protein. In Exercise Science, these two friends and colleagues translate the world of exercise science for the rest of us — separating the hype from the hard evidence.

Think you know how to build muscle? In our third episode, Martin Gibala does some mythbusting with two of the world’s most prominent experts in the science of strength development, Stuart Phillips and special guest Dr. Brad Schoenfeld, a professor of exercise science at Lehman College in the Bronx, New York. 

In addition to being a former bodybuilder and joining Stu on the ACSM strength position statement, Schoenfeld literally wrote the textbook on strength training. Together, Phillips and Schoenfeld use science and savvy to correct some of the resistance world’s most pervasive myths, including: 

• Light loads don't increase muscle size

• You have to train to absolute failure to maximize muscular adaptations

• Short rest periods are best for hypertrophy

• Cardio kills gains

• Narrow post-exercise anabolic window of opportunity

Join us to discuss these myths and more in the latest episode of Exercise Science! 

Have a listener question or an idea for an episode? Email us at realexercisescience@gmail.com

Exercise Science is powered by ⁠⁠EverMe⁠⁠. Download EverMe for free at your favourite App store. ⁠⁠

LINKS

Exercise Science is everywhere @realexercisescience: Substack. YouTube. TikTok. Instagram. Apple Podcasts. Spotify. On X you can find us @realexscience. 

Stu is everywhere, too, but mostly on Instagram and X. Follow him on TikTok to make him feel nice!

Marty just started his own Instagram. Give him a follow! He’s also on X!Whoa Brad Schoenfeld is HUGE on Instagram! One of the best feeds out there for the up-to-the-minute science on strength training. Plus here’s his lab at Lehman College.ACSM Position Statement on Resistance Training 2026

Brad’s textbook: Science and Development of Muscle Hypertrophy, 2nd Edition

Resistance Training Beyond Momentary Failure⁠⁠⁠ - Brad Schoenfeld, co-author

Divergent strength gains but similar hypertrophy after low-load and high-load resistance exercise training in trained individuals: ⁠⁠⁠many roads lead to Rome⁠⁠⁠

Exercise Science is produced by Ghost Bureau, the Toronto content marketing agency. 

DISCUSSION POINTS

00:00 Strongest exercise scientist?

02:13 Schoenfeld intro

03:47 Myth 1: Must lift heavy

06:25 Myth 2: Must train to failure

10:52 Myth 3: Short rest periods

17:26 Myth 4: Anabolic window

26:33 Myth 5: Cardio kills gains

36:54 LQ: Losing gains

DISCLAIMER

The Exercise Science podcast is for educational and entertainment purposes only and is not a substitute for professional medical advice. Strength training and fitness carry inherent risks. Always consult with a physician or qualified healthcare provider before starting any new exercise program or making changes to your diet. The hosts, producers, sponsors and guests of this podcast disclaim any liability for any injuries or losses connected with the information discussed in this show.

The science of strength and fitness is continually evolving. While we strive to provide accurate, evidence-based information, we make no representations or warranties regarding the completeness, accuracy, or timeliness of the information discussed.