PeakO2® Mushroom Supplement – The Ultimate Guide & Review

PeakO2® is a trademarked blend of 6 adaptogenic mushrooms with clinical evidence for increasing power and endurance and attenuating physical and mental stress. Here we’ll examine its properties, mechanisms, effects, benefits, and applications.

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In a hurry? Here are the highlights:

• PeakO2® is a trademarked, patent-pending blend of select mushrooms created by Compound Solutions.
• It has clinical evidence for increasing power output and endurance and attenuating physical and mental stress.^​1​
• Specifically, PeakO2® increases oxygen uptake and improves oxygen utilization. As such, PeakO2® can be particularly useful for both weightlifters and endurance athletes.^​1​
• The 6 types of mushrooms are Cordyceps, Reishi, Trumpet, Shiitake, Lion’s Mane, and Turkey Tail.
• PeakO2® seems to be better than beta-alanine at improving performance.
• The types of mushrooms in PeakO2® have been studied for years and may confer other health benefits outside of augmenting physical performance.
• PeakO2® is natural, non-GMO, non-allergenic, vegan, gluten-free, and USDA certified organic.
• PeakO2® is safe and easy to supplement, and is featured in a number of pre-workout supplement blends. You can also buy it by itself.

Product Mentions:

– Genius Muscle
– Xtend Elite
– Primaforce Peak O2
– Jacked Factory Build XT

What is PeakO2?

PeakO2® is a trademarked blend of 6 adaptogenic mushrooms created by Compound Solutions, the makers of Dynamine® and TeaCrine®. PeakO2® is natural, non-GMO, non-allergenic, vegan, gluten-free, and USDA certified organic. The mushrooms in PeakO2® are grown on organic whole oats to maximize beta glucan content and bioactive compounds.^​1​

The 6 types of mushrooms in PeakO2® are:

• Cordyceps (Cordyceps militaris)
• Reishi (Ganoderma lucidum)
• King Trumpet (Pleurotus eryngii)
• Shiitake (Lentinula edodes)
• Lion’s Mane (Hericium erinaceus)
• Turkey Tail (Trametes versicolor)

Note that the specific syntax for the name varies somewhat across the web, print materials, and nutrition labels. You may see any of the following, all referring to the same ingredient:

• PeakO2
• Peako2
• PeakO₂
• Peako₂
• Peak O2
• Peak o2
• Peak O₂
• Peak o₂

For the sake of formatting and readability in this post, I’ll be using the first bolded form.

PeakO2 Benefits

• Boosts relative peak power output (RPP).
• Improves endurance.
• Attenuates physical and mental stress.
• Increases time to exhaustion (TTE).
• Increases VO2 max.
• Increases exercise capacity.
• Improves exercise economy.
• Increases peak strength.
• Improves ventilatory threshold (VT).
• Decreases recovery time.

PeakO2’s Mechanism of Action — How Does it Work?

In a nutshell, PeakO2’s primary mechanism of action seems to be increasing oxygen uptake while also improving oxygen utilization, thereby expediting ATP regeneration and preserving more muscle glycogen. It’s also thought that Cordyceps militaris specifically may improve blood flow and lactate clearance and reduce oxidative stress, allowing one to continue performing high-intensity exercise for longer.^​2–5​ These effects may sound simple, but their downstream ramifications are significant and widespread.

PeakO2 and VO2 Max

Studies have indicated that PeakO2® reliably increases VO2 max.^​6​ This is arguably its most important effect, so it’s fitting that “O2” is in the name.

As the name implies, “VO2 max” refers to the maximum amount of oxygen one can utilize during exercise, measured in milliliters of oxygen consumed in 1 minute per kilogram bodyweight (mL/kg/min). This metric is useful for measuring aerobic capacity and cardiovascular function.

Getting your VO2 max requires a lab test with special equipment, which is why it’s usually reserved for elite athletes. Picture the cliché image of a person running on a treadmill while wearing a ventilation max and electrodes connected to a monitor displaying a graph in real time while someone in a white coat jots down notes on a clipboard. Some gyms and health clinics now offer VO2 max testing; just be sure to choose a reputable facility for accuracy.

In a VO2 max test, the mask you wear measures the volume of oxygen you breathe in and the amount of air you breathe out while running on a treadmill or cycling on a stationary bike. As the exercise intensity/speed gradually increases, your oxygen intake also increases until you reach a “max” intake – a plateau – where you no longer take in more oxygen even though the exercise intensity is still increasing. That maximal uptake is your VO2 max. Beyond that point is when fatigue begins and one will likely have to cease exercising or reduce intensity. The theory goes that increased oxygen consumption results in greater ATP generation.

Now you can see how PeakO2®, in increasing one’s VO2 max, increases workload capacity and time to exhaustion and delays the onset of fatigue. This is obviously a significant benefit for runners, cyclists, and other endurance athletes.

One study showed that PeakO2® provided an 11% increase in VO2 max for participants on average.^​6​

Note that VO2 max, like heart rate, is relative, and obviously varies greatly based on factors like age, gender, fitness level, altitude, etc.; there is not necessarily a “good” VO2 max number to which you can arbitrarily compare yourself, but there are averages for people with characteristics similar to yours. This is why the accuracy of measurement is important.

PeakO2 and Time to Exhaustion (TTE)

Somewhat related to VO2 max is “Time to Exhaustion,” abbreviated TTE. This is also sometimes called “time to failure.” It is a measure of endurance. Time to Exhaustion, as the name suggests, is the amount of time for which a given power or intensity can be maintained until that power can no longer be maintained. For a hypothetical example, given some specific work rate, a cyclist’s TTE may be 30 minutes.

PeakO2® supplementation has been shown to increase TTE by 8% on average.^​6​

PeakO2 and Ventilatory Threshold (VT)

VT1 refers to the “first ventilatory threshold,” the point during exercise at which one’s breathing rate begins to increase. At VT1, you are not able to talk comfortably, but you can still string some words together, and you are not “out of breath.” VT2, or the “second ventilatory threshold,” occurs when one reaches the point at which they are “out of breath.” For example, a sedentary person may reach VT1 while walking briskly, VT2 while jogging, and VO2 max while running. For most people, VT1 lies somewhere between 50% and 75% of their VO2 max.

PeakO2® has been shown to increase VT by a whopping 41%.^​6​

PeakO2 and Relative Peak Power Output (RPP)

RPP is a measure of power output, reflecting the ability of ATP to produce energy. Using a Wingate Test, developed at the Wingate Institute in Israel in the 1970’s, on a mechanically braked bicycle ergometer, peak anaerobic power is expressed in Watts using Force x Distance. Relative peak power simply divides peak power by one’s body mass and is expressed as W/kg.

PeakO2® has been shown to increase RPP by 8%.^​6​

Other Health Benefits from PeakO2

We have known for a while that medicinal mushrooms elicit immunopotentiating, immunomodulating, and neuroprotective effects, specifically antioxidant, antitumor, and anticancer, as well as generally being anti-fatigue. We also know that these mushrooms are what’s called “adaptogenic,” helping the body “adapt” to both physical and mental stress, of which a specific primary effect is lowering cortisol.^​7–9​ These types of benefits are beyond the scope of this article, but I figured they’re worth mentioning.

About PeakO2’s Creators

Compound Solutions are leaders in the sports nutrition and supplementation industry. Their efforts in advancing scientific research for maximizing human performance are admirable and well-known. In their words, they “believe science and research is paramount to human performance.” I can get behind that.

I had actually been using PeakO2® in my supplement regimen for a while without knowing much about the company itself. It makes sense that PeakO2® is yet another exciting science- and research-backed, results-oriented compound from these guys.

Watch Compound Solutions CEO Matt Titlow talk briefly about PeakO2® and its benefits in the video below.

Here’s a similar bonus video below summarizing the findings of the studies we’ll look at further down. Not a huge fan of Thomas DeLauer, but he’s just the speaker here; the video itself is from Compound Solutions.

Lastly, Sandra Carter from M2 Ingredients discusses the unique manufacturing process that preserves PeakO2’s bioactive compounds in this video:

PeakO2 Studies

Two clinical studies have been conducted specifically on PeakO2® in humans.

I’ve referenced the first several times above already. It was a double blind study conducted at the University of North Carolina Chapel Hill that looked at the effects of daily PeakO2® supplementation for 3 weeks in young, recreationally active adults. Half of the participants took PeakO2® mushrooms and the other half took maltodextrin (placebo).^​6​ All participants underwent several types of exercise tests. As discussed already, after 3 weeks, the mushroom group saw:

• Increase in VO2 max (44 to 48.8; +11%)
• Increase in TTE (+70 seconds; +8%)
• Increase in VT (1.7 to 2.4; +41%)
• Increase in RPP (5.9 to 6.4; +8%)

These findings were consistent with previous studies conducted on Cordyceps years prior.^​2​

Researchers also looked at PeakO2® supplementation of 1 week vs. 3 weeks, as previous studies have shown little to no effect from small acute doses. They found that benefits after 1 week were minimal, and benefits after 3 weeks were much greater.^​2​

The second study, conducted at my alma mater College of Charleston, looked at a higher dose (12g/day) over 1 week compared to a lower dose (1-2g/day) over 4 weeks.^​10​

As in the first study, after 4 weeks of daily supplementation, participants saw significant improvements in VO2 max, VT, TTE, blood lactate, and power output compared to placebo. The participants in the 1-week high-dose group exhibited little to no benefits, with some benefits being seen for lower-baseline-aerobic-capacity participants. This makes sense, as people with greater levels of physical fitness have less room for improvement.^​10​

More research is needed to further dial in an optimal dosage protocol, but these studies give us a great starting point with clear ergogenic effects. It would also be nice to see future research look specifically at PeakO2’s effects on muscle hypertrophy, muscle protein synthesis, strength gains, fat metabolism, and body composition, particularly in trained individuals.

Secondly, I’d also like to see future studies investigate the potential ergogenic effects of the other mushrooms in PeakO2® besides Cordyceps. Looking at the historical research, Cordyceps seems to be the shining star here, and may be responsible for the “bulk” – if not all – of PeakO2’s efficacy. We also don’t know the exact weighting of each mushroom type in PeakO2® because it’s a proprietary blend; it could very well be mostly Cordyceps.

Lastly, I would think it is obvious that we need to look at the potential ergogenic effects of whole fruiting body extracts of real mushrooms versus mycelium on grain (MOG), since we know PeakO2® is the latter.^​11​ Mycelium supplements are known to potentially contain up to 75% starch, which invariably means a small amount of actual fungal material and a smaller amount of beneficial compounds like beta-glucans, triterpenoids, etc. Specifically, mycelium-on-grain products only contain about 6% beta-glucans on average, whereas real mushrooms have an average of about 35%.^​12,13​

I would argue it’s quite possible or even probable that whole fruiting body extracts of real mushrooms would yield greater ergogenic effects than what we’ve seen from the mycelium of PeakO2®, or that the same effects could be achieved with a lower dosage. Whole fruiting body mushroom extracts with higher beta-glucan content would also produce greater secondary health benefits.

My PeakO2 Review

I was already somewhat familiar with the exercise-capacity-augmenting effects of both Cordyceps militaris and Cordyceps sinensis. These particular mushrooms came on the scene in the early ’90’s after it was observed that the nutrition regimen of record-breaking Chinese athletes included Cordyceps supplementation. It has been shown repeatedly that high-dose Cordyceps specifically enhances exercise performance.^{​14–16​} Cordyceps militaris tends to be more widely used now than Cordyceps sinensis after it was found that the militaris species seems to contain comparatively more bioactive compounds.^​17​

In a general, subjective sense, I can definitely tell that breathing has become easier in the gym, endurance is increased, and fatigue is delayed. In terms of taste, powdered mushrooms oddly usually actually look, smell, and taste like raw cocoa powder, so think of an earthy dark chocolate. It goes great with coffee or a chocolate protein shake, or can be covered up by a tart pre-workout drink.

Again, I think the research definitely needs to look at whole fruiting body extracts of real mushrooms in the future and compare their potential ergogenic effects to those of PeakO2’s mycelium. Neither M2 Ingredients nor Compound Solutions mentions anything about the beta-glucan or starch content of PeakO2®. In fairness, they may not even test for it, and I can’t really argue with the clinically-verified results of the PeakO2® blend per se.

PeakO2 vs. Beta-Alanine

Beta-alanine is an amino acid with clinical evidence for improving muscular endurance and delaying fatigue, and has long been a staple in pre-workout supplements for that reason.^{​18–20​} PeakO2® seems obviously superior to beta-alanine for a number of reasons:

• Beta-alanine has no significant, reliable effect on power output or VO2 Max.
• Beta-alanine only shows a modest 3% improvement in muscular endurance measured by TTE, compared to 8% for PeakO2®.
• Beta-alanine supplementation produces a harmless yet annoying tingling/itching sensation called paresthesia. Some people actually like the tingles; I personally can’t stand them.
• Beta-alanine’s benefits only show up after a saturation point of 179g is reached after supplementing about 3g daily.
• Similarly, beta-alanine’s effects don’t “kick in” until after 60 seconds of continuous exercise, which is obviously longer than most weightlifting sets.

In summary, PeakO2® should produce greater results in a shorter amound of time.

Is PeakO2 Safe?

The mushrooms in PeakO2® have been eaten and studied for decades, and they are grown and milled in a GMP-certified facility by M2 Ingredients. PeakO2® is perfectly safe for human consumption.

PeakO2 Side Effects

Side effects from PeakO2® seem to be extremely rare. I’ve seen a few people complain of gastrointestinal distress.

PeakO2 Dosage

The clinically effective dosage from recent studies for an ergogenic effect from PeakO2® supplementation appears to be around 3-4g daily, requiring at least 3 weeks of supplementation, with longer chronic consumption likely yielding greater ergogenic effects. Timing seems to be unimportant as long as you’re taking it daily, but directly pre-workout may yield slightly better results.^​2​

Some other bloggers have suggested this implies the potential for a “loading phase” to reach a “saturation point,” after which a “maintenance phase” can be employed, as is the case with beta-alanine and creatine, but the research doesn’t seem to support a saturation point per se, at least not as it applies to 1 week of supplementation. Remember, Dudgeon et al noted little to no benefit from the treatment group that supplemented 12g/day for 1 week. That’s a total consumption of 84g, which is equal to the Hirsch et al study of 4g/day over 3 weeks, yet Hirsch et al saw much greater effects.^​2,10​ Hirsch et al specifically concluded that “it is difficult to discern if a loading period is beneficial or necessary.”^​2​

Studies seem to indicate a dose-dependent response up to 4g/day, provided one is supplementing daily for at least 3 weeks. Again, Dudgeon et al found little to no benefits from the 1-week high-dose (12g/day) group and greater benefits from the 4-week low-dose (1-2g/day) group. Hirsch et al saw greater ergogenic effects after 3 weeks at 4g/day than any of the groups from Dudgeon et al.^​2,10​ Moreover, past research showed no benefit from acute supplementation (2 weeks) of Cordyceps sinensis in elite cyclists.^​21​

So rather than a saturation dosage, I would argue there may be a saturation time period, given a sufficient daily dosage, for the body to adapt. I don’t want to speculate as to what that implies pharmacokinetically.

PeakO2 Supplements

Over the past few years, PeakO2® has been included in a number of pre-workout supplement powders.

PeakO2 Powder

You’re usually going to find PeakO2® in powder form, since we’re talking grams of mushrooms per day.

PeakO2 Capsules

Prefer capsules instead? Build XT is available in capsule form too.

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Medical Disclaimer:  While I love diving into and extracting useful information from clinical research related to health, fitness, supplements, and more, I am in no way a medical expert. The content on this website is for informational purposes only; it is not professional medical advice, nor is it a substitute for professional medical advice. None of the statements on this website have been evaluated by the FDA. Products mentioned are not intended to diagnose, treat, cure, or prevent any disease. Read my lengthier medical disclaimer here.