Human Performance Outliers Podcast with Zach Bitter

Dr. Trent Stellingwerff joined the show to discuss the topic of relative energy deficiency syndrome (RED-S) in endurance athletes, and body competition management. Trent is the Chief Performance Officer (CPO) at the Canadian Sports Institute. Trent has developed many national and international collaborations in various applied research projects in the fields of nutrition and physiology, and been a part of 8 IOC position statements. Trent joined the show to discuss the topic of relative energy deficiency syndrome in endurance athletes, and body competition management in athletics.
Trent: csipacific.ca/team-members/trent-stellingwerff | X: @TStellingwerff
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Mark Dowdle arrives 15 minutes before the start of Last Soul Ultra, but still wins with nearly 400 miles. Should we have more unsupported ultra running events? Badwater 135 lack of streaming and interesting shoe policy. Jeff Garmire joins me to discuss and share his upcoming documentary.
Jeff Garmire: freeoutside.com | IG: @thefreeoutside | YT: @Freeoutside
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Find Zach: zachbitter.com | IG: @zachbitter | X: @zbitter | FB: Zach Bitter | Strava: Zach Bitter

Matt Fox joined me to chat about his interest in the marathon after coming from a National class middle distance background, his trajectory with content creation, the Chinese running shoe market, and his power weight ratio journey. 
Matt Fox: sweatelite.co | IG: @mattinglisfox
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Episode summary: Zach Bitter interviews Matt Fox (Sweat Elite)
Matt's background: Former Australian middle-distance runner who twice finished 5th at Olympic/World trials (consistent 1:48 800m). Felt he "failed" after never making a national team, which later fueled his curiosity about how better runners train.
How Sweat Elite started: After a failed Strava-like app, Matt launched a site interviewing pros. He later began filming elite workouts (inspired by old FloTrack videos), but it lost money due to last-minute travel costs and limited YouTube revenue. He recouped losses by documenting his own marathon builds.
Content landscape: Athletes now prefer posting their own journeys, making third-party workout videos harder. Influencers-as-coaches is a growing issue; both agree formal qualifications aren't required (many great coaches never had them), but buyers should do due diligence. Bad influencer coaches can still introduce people to the sport who later seek better help.
Creators they follow: Truett Haynes (humor + ambitious Olympic Trials goal despite current times being far off; recently hired Rory Linkletter). Also Eric Floberg (cinematography) and Rory Linkletter (authenticity, Canadian marathon record pursuit).
Weight/body composition debate: Matt accidentally got very lean (70 kg) for a 2:20 marathon, then gained 3–4 kg and plateaued at 2:23–2:24. After noticing he was much larger than the Japanese runners he raced with, he used carb-cycling (high carbs around key sessions, deficit on easy days) to drop back to ~69 kg and ran 2:18–2:19. He has since lost another ~12 kg.
He stresses this is highly individual and risky. Personality matters: people with OCD/obsessive tendencies are more likely to develop RED-S or eating disorders. He now studies nutrition to give safer guidance.

Examples cited: Josh Kerr's long-term leaning-out, George Cush dropping weight before winning Comrades, Ryan Hall hitting a point where further loss hurt performance.

Both emphasize timing (fuel hard sessions, restrict on recovery days), not living in a perpetual deficit, and resetting after races.

Chinese super shoes: Matt recently lab-tested 12 models from Anta, Li-Ning, 361°, Xtep, Dynafish, etc. Many perform comparably to Western shoes at half the price and often last longer. Notable mentions: Li-Ning Dragon Flight (79 g, technically illegal but extremely fast; a legal version is coming), Anta C10 (very similar to Puma Fast-R), Dynafish trainer (versatile, durable, sub-200 g).
Barriers in the U.S.: high tariffs, limited specialty-store distribution, and brands currently focused on the Chinese market. Anta and Li-Ning are expanding globally.

Matt's current status: Recovering from injury, posting daily on Instagram/Strava as Matt Fox. Targeting a 2:17 or faster at the Melbourne Marathon in two months.
Timestamps:
0:00:02 — Intro and welcome to the episode
0:00:45 — Matt shares his background and connection to the podcast
0:01:42 — Matt's unusual running journey and early Sweat Elite work
0:04:33 — Matt's competitive middle-distance background and Olympic trials attempts
0:05:50 — Stepping away from elite running and building Sweat Elite
0:07:19 — From a failed app to interviewing pro runners
0:09:06 — Building content, monetization challenges, and workout videos
0:13:10 — Athletes making their own content and the creator/brand shift
0:14:36 — Should influencers need qualifications to coach?
0:21:08 — Coaching credentials and the role of experience
0:22:34 — Content creators Matt is excited about
0:25:46 — Truett Haynes, Rory Linkletter, and the entertainment factor
0:31:34 — Transition to weight, performance, and body composition
0:33:19 — Matt's marathon progression and how weight loss affected performance
0:40:27 — The nuance of weight loss, RED-S, and individual differences
0:48:32 — Why the conversation is different for different runners
0:50:22 — Timing carbohydrates and avoiding energy deficiency
0:52:19 — George Kusche at Comrades
0:57:30 — Josh Kerr seemingly fully optimized
01:03:12 — Chinese running shoes and why they matter
01:06:12 — Jack Crago and testing Chinese shoe models
01:08:25 — Distribution, tariffs, and market access in the U.S.
01:13:02 — Shoe durability and foam life
01:15:28 — Lightest legal shoes and new tech from Chinese brands
01:17:42 — Anta, Puma, and the global shoe market
01:19:04 — Puma concept shoes and performance development
01:20:49 — Why Chinese brands are expanding more slowly in the West
01:22:12 — Matt's trip to China and how he got deeper into shoe tech
01:23:54 — Dynafish and ultra-light trainers
01:26:12 — Wrap-up, where to find Matt, and final thoughts

I reached the end of my journey with the blood clot I discovered at the end of June. I learned a lot through the process, along with information about my personal risk for blood clotting. I unpack all of that and share my return to training. 
Episode Sponsors:
LMNT: drinkLMNT.com/HPO (free sample pack with purchase)

deltaG: deltagketones.com Code: BITTER20 (20% Off)

Kila Insoles: kilarun.com Code: BITTER ($50 Off)

Podcast Details:
Support HPO: zachbitter.com/hposponsors

HPO Website: zachbitter.com/hpo 

Zach's Coaching: zachbitter.com/coaching

Zach's Journal: substack.com/@zachbitter

Find Zach: zachbitter.com | IG: @zachbitter | X: @zbitter | FB: Zach Bitter | Strava: Zach Bitter

Vic Johnson shares the practical limits of high-carb strategies, discusses how carbohydrate needs can exceed what the gut can absorb, especially under heat and high intensity. Vic shares typical successful ranges, why hotter races and faster pacing worsen digestion, and emphasizes consistent intake over large boluses that can trigger GI issues. They discuss individualizing targets for mid-pack runners, finding a personal carb "cap" in training then scaling back for race day, sex differences (body size, culture, psychology), links between GI issues and disordered eating, the role of day-to-day carb intake in building intestinal transporters, and practical choices between drink mix vs gels.
Vic Johnson: mountainsportsnutrition.com | IG: @mountain.sports.dietitian
Episode Sponsors:
LMNT: drinkLMNT.com/HPO (free sample pack with purchase)

deltaG: deltagketones.com Code: BITTER20 (20% Off)

True Nutrition: truenutrition.com/hpo Code: HPO (20% Off)

Podcast Details:
Support HPO: zachbitter.com/hposponsors

HPO Website: zachbitter.com/hpo 

Zach's Coaching: zachbitter.com/coaching

Zach's Journal: substack.com/@zachbitter

Find Zach: zachbitter.com | IG: @zachbitter | X: @zbitter | FB: Zach Bitter | Strava: Zach Bitter