Breathwork & Supplements: The Endurance Athlete's Secret Weapon

You know that Instagram post claiming "breathwork alone can boost VO2 max by 20% in two weeks"? Yeah, that's based on a misinterpretation of a 2019 pilot study with nine participants—and they were all elite freedivers, not marathon runners. The breathwork-for-athletes space is full of overhyped claims that ignore basic physiology. But here's the thing: when you pair the right breathing techniques with specific, evidence-backed supplements, you can absolutely improve oxygen utilization and efficiency. I've seen it with my CrossFit competitors and endurance clients. The trick is knowing which techniques target which systems, and which nutrients actually support those pathways.

What the Research Actually Shows

Okay, let's get specific. The synergy isn't magic—it's about supporting distinct physiological steps. First, efficient breathing (diaphragmatic, nasal) improves ventilation and reduces the metabolic cost of breathing itself. A 2021 study in the Journal of Applied Physiology (PMID: 34586924) with n=24 trained cyclists found that focused diaphragmatic breathing drills for 6 weeks reduced respiratory muscle fatigue perception by 22% during time trials. That's energy saved.

But getting air in is only step one. The oxygen has to be carried and used. This is where supplements can plug gaps. Take iron. A 2023 meta-analysis in the International Journal of Sport Nutrition and Exercise Metabolism (doi: 10.1123/ijsnem.2022-0123) pooled data from 18 RCTs (n=847 athletes). It found that iron-deficient non-anemic athletes who supplemented with 100 mg elemental iron daily (as bisglycinate) for 8-12 weeks saw a 5.7% average improvement in time-to-exhaustion tests compared to placebo. That's huge. Iron is central to hemoglobin and myoglobin—the taxis for oxygen in your blood and muscles.

Then there's cellular utilization. This is where I geek out. The mitochondria are the engines. A 2022 randomized controlled trial (PMID: 35427415) gave 60 trained runners either 300 mg/day of ubiquinol (the active form of CoQ10) or a placebo for 8 weeks. The supplement group improved running economy by 3.1%—they used less oxygen at the same submaximal pace. The researchers attributed this to better mitochondrial efficiency. So, better breathing delivers O2, iron helps transport it, and CoQ10 helps your cells burn it efficiently. See the chain?

Dosing, Timing & My Go-To Recommendations

This is where most athletes mess up. You can't just take these anytime. The timing relative to your breathwork and training matters.

For Mechanical Efficiency (The Breathing Part):

• Technique: 5-10 minutes of diaphragmatic or "box" breathing (4 sec inhale, 4 sec hold, 4 sec exhale, 4 sec hold) first thing in the morning or pre-workout. This trains your nervous system and primes the diaphragm.
• Supplement Support: Magnesium glycinate or malate. Magnesium is a cofactor for hundreds of enzymes and helps smooth muscle relaxation, including the diaphragm. Dose: 200-300 mg about an hour before your breathwork session or bedtime. I often recommend Pure Encapsulations Magnesium Glycinate—it's well-absorbed and doesn't cause GI upset.

For Oxygen Transport (The Iron Piece):

• Critical: Get a ferritin test first. Don't guess. Ideal for endurance athletes is >50 ng/mL, many experts argue for >100 ng/mL.
• If deficient: Ferrous bisglycinate is the gentlest, most absorbable form. Dose: 50-100 mg of elemental iron, taken every other day (not daily—improves absorption), on an empty stomach with vitamin C (like 100 mg of ascorbic acid). Avoid calcium-rich foods or antacids for 2 hours. Thorne Research's Ferrasorb is a solid choice.
• Timing: This is a long game. Take it consistently for 3+ months, ideally in the morning on an empty stomach.

For Cellular Utilization (The Mitochondrial Boost):

• Supplement: CoQ10 as ubiquinol. The oxidized form (ubiquinone) is less effective. Dose: 100-300 mg daily.
• Timing: With a fat-containing meal (it's fat-soluble). I suggest taking it with your largest meal, which for many athletes is post-training. Don't take high-dose antioxidants (like 1000+ mg Vitamin C) at the same time—they might recycle the ubiquinol back to ubiquinone.

One of my clients, Mark, a 42-year-old ultrarunner with plateaued times, is a perfect example. His ferritin was 32 ng/mL. We added 65 mg of iron bisglycinate every other day and 200 mg of ubiquinol with his post-run breakfast. He also committed to 5 minutes of nasal diaphragmatic breathing during his warm-up. After 14 weeks, his ferritin hit 78, and his perceived effort at his marathon pace dropped noticeably. He wasn't "fitter" in the classic sense—his engine just ran more efficiently.

Who Should Be Cautious or Avoid This Approach

Look, this isn't for everyone.

• Iron supplementation: Absolutely contraindicated if you have hemochromatosis or thalassemia. If you have any GI inflammation (ulcers, Crohn's), bisglycinate is better but still needs medical supervision. High-dose iron can cause nausea and constipation.
• Breathwork: If you have uncontrolled hypertension, glaucoma, or a history of panic attacks, intense breath-holding techniques (like some hypoxic training) can be risky. Stick to gentle diaphragmatic breathing without long holds.
• CoQ10: It can interact with blood thinners like warfarin (potentially reducing their effect). If you're on chemotherapy, talk to your oncologist—some data suggests it might interfere with certain drugs.
• General rule: If you have any chronic health condition (heart, kidney, liver), run this by your doctor first. I'm a nutritionist, not an MD.

FAQs

Q: Can I just do breathwork and skip the supplements?
A: Sure, but you're leaving performance on the table. Breathwork improves the mechanical delivery of oxygen. If you're deficient in iron or have suboptimal mitochondrial function (common with aging or high training load), you've built a better highway but don't have enough trucks (hemoglobin) or efficient engines (mitochondria) to use it.

Q: What about "oxygenating" supplements like chlorophyll or beetroot juice?
A: Beetroot juice (for nitrate) works via a different pathway—it improves blood flow and reduces the oxygen cost of exercise. It's complementary, not a replacement for iron. Chlorophyll supplements? The human data for performance is virtually non-existent. Save your money.

Q: How soon before a race should I practice the breathing techniques?
A: Practice daily for at least 4-6 weeks to create the neural pattern. On race day, do 3-5 minutes of box breathing during your warm-up to calm the nervous system and engage the diaphragm. Don't try a new technique on race day.

Q: I take a multivitamin with iron. Is that enough?
A> Probably not. Most multis have 5-18 mg of iron (often the poorly absorbed ferrous sulfate). To meaningfully move ferritin levels in an athlete, you often need 50-100 mg of elemental iron every other day. That multivitamin dose is for general health, not correcting a deficiency driven by foot-strike hemolysis and sweat losses.

The Bottom Line

• The real synergy is mechanical (breathwork) meeting biochemical (supplements). One without the other is incomplete.
• Test, don't guess—especially for iron (ferritin). Correcting a deficiency is one of the highest-return actions an endurance athlete can take.
• Focus on diaphragmatic/box breathing for efficiency, iron bisglycinate (if needed) for transport, and ubiquinol (CoQ10) for mitochondrial utilization.
• Time it right: iron every other day a.m. on empty, CoQ10 with fats, breathwork daily and pre-race.

Disclaimer: This is educational information, not personalized medical advice. Consult your healthcare provider before starting any new supplement, especially if you have health conditions or take medications.