Signal is Barbell Medicine’s evidence-based framework for understanding testosterone testing, low testosterone, TRT, and the health factors that shape the signal you’re seeing.
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New from Barbell Medicine
Your testosterone level is a signal. It points at what’s going on underneath the hood: your general health, sleep, body composition, exercise habits, medications, and medical history.
Most low testosterone lab results are not isolated hormone problems. Signal is an evidence-based framework for understanding what your labs are actually telling you, what to do next, and when testosterone therapy is — and is not — appropriate.
Digital edition available now. First hardcover printing sold out while pre-orders are being fulfilled. Hardcover and bundle ordering will reopen soon.
Hardcover ordering will reopen once current pre-orders have been fulfilled.
Why Signal Exists
In 1889, a renowned French neurologist injected himself with extract of animal testicles and announced at a medical conference in Paris that he had found the fountain of youth. The press picked it up. A professional baseball pitcher used it before a game and threw a shutout. The Washington Post called it proof.
The extract contained essentially no testosterone. Brown-Séquard was injecting himself with placebo.
More than 135 years later, the testosterone-as-elixir narrative still drives a multi-billion-dollar industry. Men are being medicated for problems they do not have, missing problems they do have, and trying to interpret labs without a clear framework for what those labs actually mean.
Signal is that framework. It was written to help patients, clinicians, coaches, and lifters understand what testosterone levels are actually telling them — and what to do next.
The Problem
The testosterone conversation is full of confident answers. The hard part is knowing whether the right question has been asked in the first place.
Roughly a quarter of testosterone prescriptions written in the U.S. between 2002 and 2013 were initiated without a confirming lab. The drug was started on symptoms alone.
Baillargeon et al., JAMA Internal Medicine, 2015
More than half of men meeting criteria for symptomatic androgen deficiency experienced remission by the next study wave without any intervention.
Travison et al., Journal of the American Geriatrics Society, 2011
In population studies, many men aged 45 and older meet criteria for testosterone deficiency, while only a minority receive treatment.
Mulligan et al., International Journal of Clinical Practice, 2006
Men are being medicated for problems they do not have, missing problems they do have, and trying to make treatment decisions without a clear diagnostic framework. Signal was written to walk through that step at the level of detail it deserves.
Testosterone does not exist in isolation. Signal helps you interpret the lab result in the context of health, training, sleep, body composition, and treatment decisions.
Signal digital edition is available now. The first hardcover printing has sold out while existing pre-orders are being fulfilled. Hardcover and bundle ordering will reopen soon.
Choose Your FormatShipping is calculated at checkout for hardcover and bundle orders.
FAQ
No. Signal is a framework for evaluating whether testosterone therapy is appropriate in the first place, and what to do if it is not.
Most of the book covers what a testosterone result is actually pointing toward: testing issues, sleep, body composition, training, nutrition, medications, medical history, and other underlying drivers. The TRT chapter covers the evidence so readers can make a more informed decision.
Yes. The TRT chapter, monitoring discussion, fertility considerations, and cessation section are especially relevant for people currently using testosterone therapy or thinking about coming off.
The book also covers the broader diagnostic framework, which can help you understand whether testosterone therapy is addressing the underlying issue or only changing the number.
All three. The main text is written for motivated non-clinical readers, while the deeper clinical material is designed to be useful for physicians, NPs, PAs, coaches, and other professionals who help people navigate testosterone questions.
The goal is to give readers a defensible framework they can use in conversation with a clinician, patient, or client.
The hardcover is the physical edition of Signal.
The digital edition is an EPUB delivered through BookFunnel. It can be read in your browser or the BookFunnel app, or transferred to a compatible e-reader.
The hardcover + digital bundle includes both editions. Your digital copy is delivered through BookFunnel, while the hardcover is shipped separately.
Digital purchases are fulfilled through BookFunnel. After your purchase, you’ll receive access to your copy of Signal through your BookFunnel library.
You can read the book in your browser or the BookFunnel app, or transfer the EPUB to a compatible e-reader. Use the same email address you used for your Barbell Medicine order when accessing your BookFunnel library.
BookFunnel also provides reader support if you need help accessing or transferring your book.
Yes. The digital edition is delivered as an EPUB through BookFunnel, giving you flexibility to read in the BookFunnel app or browser, or use the file with a compatible e-reader.
Shipping is calculated at checkout based on your address for hardcover and bundle orders. Digital-only purchases do not require shipping.
If you purchase the hardcover + digital bundle, your digital edition is delivered separately through BookFunnel and does not depend on shipment of the hardcover.
The podcast series covers many of the conclusions and key pieces of evidence. The book delivers the complete framework, case studies, decision tree, and protocol-level detail.
If you listened to the podcast and want the full system in one place, Signal is where it lives.
Not currently. If an audio edition becomes available, we’ll announce it separately.
Hardcover orders are covered by a 30-day money-back guarantee. Email support@barbellmedicine.com if you need help with a refund.
Digital editions are not refundable once delivered.
We are working to make Signal available through additional book retailers and distribution channels. Availability may vary by format and retailer.
You can purchase the hardcover, digital edition, or hardcover + digital bundle directly from Barbell Medicine here.
Signal: What Testosterone Levels Are Telling You About Your Health by Jordan Feigenbaum, MD and Austin Baraki, MD.
Choose Your FormatDigital edition available immediately
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| Book Type | Digital, Hardcover, Hardcover + Digital Bundle |
