In this episode of Iron Culture, hosts Eric Trexler and Eric Helms discuss various topics including the ongoing debate about the relationship between muscle growth and strength gains. They discuss brand new findings from the largest and longest-running study on resistance training, explore the implications of "apparent" sex differences in strength gains, and emphasize the need for nuanced statistical analysis in understanding the factors that contribute to strength gains and observed sex differences.

Want to read a thorough analysis of the article we discussed in this episode (and many more)? Support the show by joining the MASS Community at massresearchreview.com

Chapters

00:00 Intro

09:10 The Debate on Muscle Size and Strength

12:30 New Research on Muscle Strength and Size

20:45 Exploring Sex Differences in Muscle Training

26:40 The Hierarchy of Evidence in Research

32:00 Relationships Between Strength And Muscle Size

36:40 Lifting For Sport: History And Changing Cultural Norms

39:00 Back To The Study Results (Understanding Sex Differences in Strength Gains)

42:15 Nuances of Statistical Analysis: Relationships Between Strength And Muscle Size

54:10 Aside About Collegiate Sports In USA

56:50 Causal Discovery Analysis in Strength Research

1:08:00 Summary and Conclusions: The Role of Muscle Growth in Strength Gains

1:21:45 Listener Question: Sample Sizes in Exercise Science

1:27:10 Outro

In this episode of Iron Culture, hosts Eric Helms and Michael Zourdos engage with Dr. Zac Robinson to discuss his dissertation research on the effects of resistance training volume on muscle adaptations. The conversation delves into the complexities of individual responses to training, the importance of research design, and the implications of findings for coaching practices. They emphasize the need for caution in interpreting data and the evolving nature of sports science, highlighting the significance of collaboration and flexibility in training approaches.

Chapters

00:00 Introduction and Guest Introduction

06:25 The PhD Journey and Team Dynamics

11:32 Dissertation Overview and Research Focus

18:43 Research Methodology and Individual Variability

26:50 Understanding Individual Response Variation in Training

32:09 Study Design: Isolating Variables in Training Responses

37:33 The Importance of Replication in Research

42:40 Findings

53:41 Limitations and Implications of the Study

01:00:17 Genetics and Individual Response Variability

01:02:59 The Dose-Response Relationship in Training

01:06:25 Shifting Perspectives on Training Individualization

01:11:00 The Role of Sports Science in Coaching

01:19:51 Future Directions in Resistance Training Research

In this episode, Drs Trexler and Helms discuss various topics including updates on Eric's surgery, the valuable (but very modest) effects of protein intake on muscle gains, incontinence after contest prep, the relationship between sleep quality and nutrient timing, the recent ban on smelling salts in the NFL, and more.

Time stamps:

00:00 Introduction

01:11 Preview of next week's episode (non-responders, hyper-responders, etc)

07:01 Trex's surgery update

12:11 Discussion on Protein Meta-Analyses and Research Updates (how much does protein intake actually matter for gains?)

33:10 Why meta-analyses differ from RCTs in terms of "expiration dates"

44:15 The Impact of Training vs. Nutrition (for muscle growth)

51:41 Q&A: Supplementation for Lifters (and Specifically Vegans Who Lift)

55:49 Incontinence, Increased Urine Output, and Contest Prep

59:16 Chrono Nutrition and Sleep Quality

01:11:28 The Role of Smelling Salts in Sports Performance (and Football)

In this episode of Iron Culture, Helms and Trex have a lengthy discussion about the ECA stack and yohimbine. The history, the mechanisms, the regulatory changes, the practical applications – you name it, they cover it. Don’t miss this episode if you have an interest in fat loss, stimulants, or dietary supplementation in general.

Also, be sure to check out the newest issue of the MASS Research Review! Learn more at massresearchreview.com

Time stamps

0:00 Intro

4:18 New issue of the MASS Research Review

10:42 Helms contest prep update

13:15 The history of the ECA stack and supplement regulation

30:07 Ephedra vs Ephedrine

35:31 Why people took ephedrine / ECA stack

36:30 Trends in PED use over time

45:00 Research on the ECA stack

50:58 Banning lifters for stimulant use

53:15 Effects of ephedrine + caffeine on metabolism and fat loss

1:02:44 What does aspirin really add to the ECA stack?

1:13:00 Do NSAIDs blunt hypertrophy?

1:21:25 How yohimbine works (and yohimbe vs yohimbine distinction)

1:31:10 Regulatory status of yohimbine

1:32:58 Practical applications

Back when Trex was a 14 year old, his wrestling coach noticed his passion for training and nutrition. This coach took Trex under his wing, and they started absorbing and applying as much information as they could. Their source material, almost exclusively, was the content produced by Dr. Jim Stoppani – primarily from magazine articles, but also from the totally novel medium of online video content. Jim was a jacked PhD with tons of “in the trenches” experience - back in 2005 that was a very rare combination, and there’s no question that people like Jim led the way for the next generation of “bodybuilding academics” like Helms and Trex.

Jim has made a huge mark on the fitness industry. Perhaps his most impressive feat is maintaining his impact and relevance as the industry has fundamentally transformed itself multiple times. Jim was the face of some of the biggest muscle magazines (in their prime), one of the most recognizable content creators when bodybuilding dot com was THE place for online fitness, and way ahead of the curve when it comes to building your own platform and leveraging mobile fitness applications. In this episode of Iron Culture, the Erics have a great chat with Dr. Stoppani about how the industry (and science communication more broadly) has evolved over the last 25-30 years.

To learn more about Jim and support his work, check out his social media channels and his website

https://www.jimstoppani.com/

Time stamps

0:00 Intro

3:22 Jim’s education

14:18 Jim’s transition to the muscle magazine industry

30:44 Jim’s bodybuilding dot com days

44:52 Fitness content creation in the age of social media: the good, the bad, and the ugly

Join hosts Eric Trexler and Eric Helms as they explore the potential "replication crisis" in exercise science, drawing parallels to the well-documented crisis in psychology. In this episode, they delve into the challenges of replicating research findings, the perils of placing too much confidence in singular studies, the importance of cautious interpretation of new studies, and the value of meta-analyses in understanding true effect sizes. Whether you're a seasoned lifter or new to the world of evidence-based practice, this conversation offers valuable insights into making informed decisions about your training.

Time stamps:

00:00 – Introduction (and Helms’ travel updates)

17:29 - Replication Crisis in Psychology: Discussion on the replication crisis observed in psychology and its implications.

32:45 – What is “replication”

44:36 – Results of “reproducibility project” in exercise science

1:00:04 – Why are replication rates so low in exercise science?

1:27:24 – What does this mean for “evidence-based fitness” and application of exercise science?

Relevant links:

www.massresearchreview.com

https://pubmed.ncbi.nlm.nih.gov/26315443/

https://pubmed.ncbi.nlm.nih.gov/40522610/

In this episode of Iron Culture, Dr. Eric Trexler and Dr. Lauren Colenso-Semple discuss science related to attractiveness, coolness, and personality type. They explore scientific studies on the factors associated with perceived attractiveness and "coolness," discussing body fat percentages and societal perceptions. The conversation shifts to how personality traits appear to predict workout preferences and engagement in fitness, then they debate the importance of matching exercise to individual characteristics.

Time stamps:

00:00 Introduction to Iron Culture and Guests

5:57 The Science of (Male) Attractiveness

10:39 Evolutionary Underpinnings of Male Attractiveness

13:53 Distorted Perceptions of Attractiveness (In the Fitness World)

20:10 The Irony of Pursuing Attractiveness

22:22 Body-Fat and Optimized Health

24:18 Surprising Article Feedback

28:50 Unrealistic Body Standards and Gender Perceptions

32:49 Achieving the Outcome Versus Doing Hard Things

35:07 Attractiveness is More Than Body Shape/Size

37:48 The Science of Being Cool

47:19 Matching Exercise To Personality Types

References:

Xia F, Sauciuvenaite J, Bissland R, Hambly C, Starr-Vaanholt L, Faries MD, et al. The relationship between body fatness and physical attractiveness in males. Personality and Individual Differences. 2025 Sep 1;243:113240.

de Jager S, Coetzee N, Coetzee V. Facial Adiposity, Attractiveness, and Health: A Review. Front Psychol. 2018 Dec 21;9:2562.

Brierley ME, Brooks KR, Mond J, Stevenson RJ, Stephen ID. The Body and the Beautiful: Health, Attractiveness and Body Composition in Men’s and Women’s Bodies. PLoS One. 2016;11(6):e0156722.

Sorokowski P, Kościński K, Sorokowska A, Huanca T. Preference for Women’s Body Mass and Waist-to-Hip Ratio in Tsimane’ Men of the Bolivian Amazon: Biological and Cultural Determinants. PLoS One. 2014 Aug 22;9(8):e105468.

Tovée MJ, Cornelissen PL. Female and male perceptions of female physical attractiveness in front-view and profile. Br J Psychol. 2001 May;92(Pt 2):391–402.

Jayedi A, Khan TA, Aune D, Emadi A, Shab-Bidar S. Body fat and risk of all-cause mortality: a systematic review and dose-response meta-analysis of prospective cohort studies. Int J Obes (Lond). 2022 Sep;46(9):1573–81.

Hu J, Chen X, Yang J, Giovannucci E, Lee DH, Luo W, et al. Association between fat mass and mortality: analysis of Mendelian randomization and lifestyle modification. Metabolism. 2022 Nov;136:155307.

Ramlau-Hansen CH, Thulstrup AM, Nohr EA, Bonde JP, Sørensen TIA, Olsen J. Subfecundity in overweight and obese couples. Hum Reprod. 2007 Jun;22(6):1634–7.

Wei S, Schmidt MD, Dwyer T, Norman RJ, Venn AJ. Obesity and menstrual irregularity: associations with SHBG, testosterone, and insulin. Obesity (Silver Spring). 2009 May;17(5):1070–6.

Liu Y, Hu X, Xiong M, Li J, Jiang X, Wan Y, et al. Association of BMI with erectile dysfunction: A cross-sectional study of men from an andrology clinic. Front Endocrinol (Lausanne). 2023;14:1135024.

https://psycnet.apa.org/doiLanding?doi=10.1037%2Fxge0001799

https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2025.1587472/full

In this episode of Iron Culture, Eric Helms interviews Dr. Stian Larsen, who shares his journey from powerlifting to becoming a researcher in exercise science. They discuss the intricacies of biomechanics, the importance of understanding squat techniques, and the latest research findings on muscle hypertrophy and resistance profiles. Stian emphasizes the need for practical applications in training and the significance of collaboration in research. The conversation also touches on future research directions and the role of education in advancing the field of strength training.

Time stamps

0:00 Introduction

4:33 Stian's Journey in Powerlifting and Coaching

16:00 Biomechanics and the Sticking Point in Squats

23:56 Understanding Muscle Forces and Training Strategies

33:04 Transitioning to Hypertrophy Research

35:43 Research on Muscle Length and Hypertrophy

48:58 Practical Applications of Research Findings

50:02 Biceps Research Findings and Surprises

1:03:28 Practical Applications of Research Findings

1:04:53 Quadriceps Hypertrophy Study Results

1:22:27 Lateral Raises and Resistance Profiles

In this episode of Iron Culture, the Erics provide some updates, corrections, and clarifications related to their recent episode exploring the science of microplastics. After that they take a brief moment to celebrate the 100th issue of the MASS Research Review, then answer listener questions on topics including: tasty meat alternatives, programming supersets, scaling dietary variables for very small/short individuals, the pros & cons of "extended release" caffeine formulations, the utility & shortcomings of BMI as a health metric, and more.

MASS is celebrating its 100th issue, but it's never to late to join in on the fun! Learn more at massresearchreview.com

Also, don't miss Iron Culture's sister podcast, ⁨@fpfpodcast⁩ hosted by MASS's very own Eric Trexler and Dr. Lauren Colenso-Semple

Time stamps (coming soon):

0:00 Intro

0:58 Revisiting microplastics (updates, corrections, and clarifications)

25:08 MASS celebrates 100th issue

34:00 Well-wishes for bodybuilding legend Ronnie Coleman

41:37 Tasty meat alternatives

47:12 Programming supersets

49:23 Scaling dietary variables for very small/short individuals

57:10 The utility & shortcomings of BMI as a health metric

1:05:03 Individual response variation to training

1:16:12 The pros & cons of "extended release" caffeine formulations

In this episode of Iron Culture, Dr. Eric Helms talks about his forthcoming article in the MASS Research Review covering the purported harms of high-protein diets. This isn’t your typical oversimplified dunk-fest that readily dismisses concerns about high-protein diets. Instead, Helms reviews a thorough paper that reviews common concerns in detail and assessed their plausibility in an objective manner. The claims include:

Claim 1 – protein reduces lifespan

Claim 2 – protein makes bones weaker

Claim 3 – protein harms kidneys

Claim 4 – protein causes diabetes

After that, Dr. Eric Trexler discusses a recent Instagram thread that pulled him into arguments against his will. The post was about his recent article on ketogenic diets and seed oils – two topics that are always bound to attract some controversy and heated debate. This conversation discusses the strengths and limitations of different types of scientific research and also touches on bias, objectivity, and the process of seeking the truth with an open mind.

Time stamps:

0:00 Intro

3:00 Helms’ new article about the purported harms of high-protein diets

19:25 Claim 1 – protein reduces lifespan

27:48 Claim 2 – protein makes bones weaker

43:38 Claim 3 – protein harms kidneys

50:53 Claim 4 – protein causes diabetes

57:22 Trex’s social media beefs – keto and seed oils

1:03:40 Types of observational studies

1:08:35 Seeking truth versus defending biases

1:17:32 Limitations versus fatal flaws

1:24:19 Limitations of RCTs (randomized controlled trials)

1:32:23 Wrapping up