Is Creatine Causing Your Shin Pain? + Splitting Training, Endometriosis for Lifters | Direct Line · May 2026

This is the free preview of the May 2026 Direct Line, our monthly AMA for Barbell Medicine Plus subscribers. Three reader questions answered in full.

We open with a mid-30s woman with bilateral shin pain and exertional foot numbness who started creatine a month ago and is asking whether the supplement is the cause. We walk through the compartment syndrome literature, the 2025 case report being passed around online and misinterpreted, what creatine actually does to total body water (and what it doesn’t), the four compartment pressure studies that exist, the Waterman 2013 demographic data on who actually gets chronic exertional compartment syndrome, and the workup we would actually run if this person walked into clinic.

Next, whether splitting your resistance training across the day affects strength and hypertrophy. We cover BBM’s general heuristic on frequency as a distribution tool for training load, the Schoenfeld meta-analyses on frequency (2016 and 2019), the wrinkle on cardiorespiratory fitness and exercise snacks, and where we go off the reservation compared to a strict evidence-based read.

We close with endometriosis for the lifter, including the seven-year average diagnostic delay, the 2022 ESHRE guideline shift away from required laparoscopy, what the menstrual cycle and performance literature actually says (McNulty 2020), why the anti-inflammatory diet narrative is mostly noise, the iron and protein levers that matter, post-operative return-to-lifting timelines, the meet-timing question, and Austin’s clinical case walk on supplement stacks and GLP-1 anti-inflammatory effects. A dedicated full episode on endometriosis is coming this summer.

The full unabridged Direct Line covers ten more questions, including where the GLP-1 strength trials actually are, why DEXA misleads on muscle mass loss, how we arrived at the Vital 5 weightings, the salt sermon for strongman, running shoes for casual runners, hernias and crunches in older lifters, the Bristol Stool Chart, Austin on coaching his residents, and a fresh reading list. Full episode on BBM Plus.

Timestamps:

Question 1 · Creatine and shin pain01:2713:21

Question 2 · Splitting your workout across the day13:2120:29

Question 3 · Endometriosis for the lifter20:29

What we cover:

The clinical workup for chronic exertional compartment syndrome and why creatine is rarely the culprit. The Schoenfeld frequency literature and why training load matters more than the day it’s distributed across. Endometriosis basics including diagnostic delay, prevalence, and the 2022 ESHRE guideline change. Why most endometriosis “diets” don’t have evidence behind them, and which nutrition levers actually matter (iron, protein, energy availability). Post-operative return to training, meet-timing options, supplement stacks, and the role of GLP-1 receptor agonists in chronic anti-inflammatory effects.

Resources:

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Waterman B.R. et al. 2013. Risk factors for chronic exertional compartment syndrome in a physically active military population. Am J Sports Med 41(11):2545-2552.

https://pubmed.ncbi.nlm.nih.gov/24036570/

Powers M.E. et al. 2003. Creatine supplementation increases total body water without altering fluid distribution. J Athl Train 38(1):44-50.

https://pubmed.ncbi.nlm.nih.gov/12937471/

Antonio J. et al. 2021. Common questions and misconceptions about creatine supplementation (ISSN position). J Int Soc Sports Nutr 18(1):13.

https://pubmed.ncbi.nlm.nih.gov/33557850/

Bruneau A. et al. 2025. Creatine supplementation associated with chronic exertional compartment syndrome: case report. [TO ADD: PMID once indexed]

Schoenfeld B.J. et al. 2016. Effects of resistance training frequency on measures of muscle hypertrophy: a systematic review and meta-analysis. Sports Med 46(11):1689-1697.

https://pubmed.ncbi.nlm.nih.gov/27102172/

Schoenfeld B.J. et al. 2019. How many times per week should a muscle be trained to maximize hypertrophy? J Sports Sci 37(11):1286-1295.

https://pubmed.ncbi.nlm.nih.gov/30558493/

ESHRE Endometriosis Guideline Development Group. 2022. ESHRE guideline: endometriosis. Hum Reprod Open 2022(2):hoac009.

https://pubmed.ncbi.nlm.nih.gov/35350465/

McNulty K.L. et al. 2020. The effects of menstrual cycle phase on exercise performance in eumenorrheic women: systematic review and meta-analysis. Sports Med 50(10):1813-1827.

https://pubmed.ncbi.nlm.nih.gov/32661839/

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