Why the Limits of Anaerobic Threshold Matter

Over fifty years, I've lived, trained, and worked with many talented athletes, including my sister, Lorraine, who ran four Olympic marathons. She has an Olympics bronze medal to cap off an impressive 28 year career as an internationally-ranked athlete. You could say I have finally figured it out. I am a late bloomer, and performing at a level I never thought possible at my age. I can go for an hour at full gas these days, and my heart rates are much higher than my estimated age-adjusted maximum. The video that follows is an example of the sustained red-lining I am talking about here.

I'm often asked where the ceiling lies for the oxygen‐consumption intensity an athlete can hold for an hour. This threshold — sometimes called the maximal metabolic steady state – marks the boundary between steady aerobic work and the rapid build-up of lactic acid. In plain terms, it's how close you can get to your VO₂ max for a full hour before your legs threaten to lock up.

PS: I won't go into detail about terms like VO2 max here, otherwise this will end up being a book, and not a short article. If you want to learn more about these complex things, look them up on the Internet.

What Is Anaerobic Threshold?

The anaerobic threshold is the point when your blood lactate starts to build up faster than it can be cleared. This is the hardest you can push and still stay in a steady state of metabolism for 40–60 minutes. In highly-conditioned elite athletes, it typically falls between 85 and 95 percent of the VO₂ max. Below this point, your body can clear lactate as fast as it produces it. Above it, acid burns in your muscles and you must slow down or stop.

Measured Limits in Cyclists and Runners

Laboratory simulations of one-hour efforts show that "elite-national class" cyclists (with a VO₂ max of around 70 ml/kg/min) can sustain 90 percent of that for the entire hour — equating to roughly 4.5 L of oxygen per minute. World-class marathon runners hit similar fractions: a recent female record-holder with a VO₂ max of 47.9 ml/kg/min maintained about 92 percent at her lactate threshold pace. In other words, the real-world limit sits in the low-to-mid-90s percent of the VO₂ max. In case you were wondering, my maximum is around 55–60. But more importantly, I can exceed more than 90% of that for about an hour or so. This is the benefit of smart training and nutrition.

Theoretical Upper Ceiling

You can't go beyond your VO₂ max for long. The highest recorded VO₂ max belongs to Norwegian cyclist Oskar Svendsen at 97.5 ml/kg/min. Even if you could sustain 95 percent of that, your one-hour steady state would max out at around 92–93 ml/kg/min. In practice, the global elite top out in the upper-80s to low-90s ml/kg/min range when holding threshold pace for an hour. But is this natural or enhanced?

Can You Hit Those Limits Naturally?

It's tempting to assume you need a performance-enhancing buffer, like bicarbonate loading, to edge into the top end of that range. In theory, you can reach 94–95 percent of your VO2 max without any help (like doping) — but only with extremely good training and nutrition. The adaptations required always take decades and a near-perfect alignment of factors:

• Genetic advantage — Some people are born with an abundance of slow-twitch fibres and extremely dense capillarisation. Their mitochondrial networks and lactate transport systems are simply off the charts.

• Decades of targeted training - High-volume zone two and three sessions stimulate mitochondrial biogenesis and up-regulate lactate transporters (MCT1 and MCT4), boosting your internal buffering capacity.

• Nutritional support — A whole-food diet rich in natural buffers – green leafy veg, grass-fed dairy, bone broths — and low in refined sugars helps your kidneys and lungs maintain PH without needing a supplement.

• Altitude and heat exposure — Living or training at moderate altitude, and including heat sessions forces your body to expand blood volume, increase haemoglobin, and improve ventilatory response.

• Mental resilience — Learning to tolerate severe discomfort is as much psychological as physiological. A lifelong freerange lifestyle builds the hardness to stay on that edge.

Taken together, these factors let an extraordinarily gifted and obsessively trained athlete brush up against nature's ceiling. But for most of us, bridging those final few percentage points naturally is vanishingly rare.

Practical Strategies to Naturally and Healthily Push Your Threshold

If you're not genetically pre-wired for the extreme end, you can still raise your threshold significantly without cheating by using Performance-Enhancing Drugs (PEDs):

• Build a strong aerobic base with consistent zone two volume.

• Include high-intensity threshold efforts weekly to sharpen acid clearance, but do this once you have the aerobic base.

• Optimise nutrition around whole, unprocessed foods to bolster your natural buffers.

• Use heat or altitude sessions sparingly to drive physiological adaptations.

• Cultivate mental toughness by embracing discomfort in training and everyday life.

Without resorting to PEDs like bicarbonate loading, these strategies can help you reach the high-80s percent of your VO2 max. If you have a healthy VO2 max, built by years of endurance training, improving this threshold will help you set new personal bests in events lasting 40 minutes to two hours. I will say here that bicarbonate loading is not considered doping in sport, but I still think it is dodgy.

Conclusion

In rare cases, the very best athletes can sustain mind-blowing percentages of VO₂ max for an hour without any external buffers that border on cheating. But it takes a perfect storm of genes, relentless training, optimal nutrition, and unshakeable mental resilience. For most of us, smart, natural ways will get most of that performance gain. There is no need for dodgy PEDs for a lifetime of highly-satisfying peak performances, and good health.