294 ‒ Peak athletic performance: How to measure it and how to train for it

KEYPOINTS

• 01

  VO2 max is a powerful longevity metric because it integrates every system.

  Olav Aleksander Bu is a Norwegian engineer turned exercise physiologist and coach. His athletes include triathletes Kristian Blummenfelt and Gustav Iden, who have won Olympic, World Championship and Ironman titles. He calls VO2 max 'the holy grail' for quantifying longevity. A great heart isn't enough: lungs, muscles, the nervous system and more must all work for you to reach a high VO2 max. Peter argues everyone, athlete or not, should know their number and how it ranks for their age and sex.

• 02

  Think of the body as an engine: oxygen in, power out, velocity as the final test.

  Rather than getting lost in metabolic pathways, Olav often treats physiology as a black box. Oxygen consumption measures fuel burned, power meters measure work, and distance per time is the ultimate outcome. If an intervention improves these, keep doing it. Elite athletes convert energy more efficiently, roughly 20% into propulsion and 80% into heat, so the same distance costs them less oxygen. The further a metric sits from velocity (power, then ventilation), the noisier it becomes.

• 03

  How a lab VO2 max test works, and why portable analyzers now rival the lab.

  On a treadmill or bike, a turbine or mixing chamber measures airflow while a sample line measures oxygen and CO2. Room air is about 20.9% oxygen, and about a quarter of the oxygen you inhale gets used. From the difference in concentrations and the volume of air breathed, the system calculates oxygen uptake. Olav's team works with the portable VO2 Master. In side-by-side testing on his athletes, who use about 6–7 L/min, it differs from lab equipment by only about 50 mL, which surprised Peter. Lab precision comes at the cost of less realistic conditions, such as cooling and how athletes move.

• 04

  Absolute versus relative numbers, and why 60-minute power beats short tests.

  Relative VO2 or watts per kg predicts hilly racing, such as the Tour de France, where power at threshold per kg historically lined up the podium. On flat courses, absolute output matters more. Blummenfelt is about 175 cm and 80 kg, built for propulsion, not looks. Olav warns that estimating 'functional threshold power' from 8–10-minute tests is misleading, because much of that energy comes from glycolysis rather than aerobic metabolism. A true 60-minute effort can't be faked, and comparing 5-minute with 60-minute power reveals sprinter versus time-trialist profiles.

• 05

  At the elite level, energy supply becomes the limiter.

  Olav's rule of thumb is about 20 joules per mL of oxygen. At 6 L/min, Peter calculates about 30 kcal per minute, or roughly 1,800 kcal per hour, far beyond what the gut can absorb. Peter cites the Weir equation as the fuller version. This is why specialization matters: Blummenfelt and Iden tested near 90 mL/kg/min for Olympic racing, but to set Ironman records the team deliberately let VO2 max fall below 80. That 'detuned the engine' toward sustainable multi-hour power, since athletes can't eat enough to train both.

• 06

  To raise VO2 max, accumulate as much work as possible near VO2 max.

  Olav reframes VO2 max training around total oxygen consumed per session, or kilojoules of work at high output, rather than a fixed interval pattern. Peter's old routine was 6–10 efforts of 5 minutes on and 5 minutes off, accumulating 30–50 minutes. Olav suggests experimenting with interval lengths to pack in the most high-output work, using heart rate near maximum as a sign you're close to VO2 max. Peter has tried everything from 30 seconds on and off to 8 minutes on and off at a 1:1 work-to-rest ratio.

• 07

  Low-intensity training isn't junk if it's mindful.

  Olav argues every session should be 'high quality.' Easy riding leaves the mental capacity to feel and refine position and movement, which hard efforts don't. Peter recalls training as a cyclist at a relaxed 200 W while hunting for the narrowest shoulder and knee position, and believes most of an approximately 5% gain came from reduced frontal area. Specialist cyclists and swimmers build this feel more than triathletes, who tend to solve problems by brute force, with swimming showing the biggest gap.

• 08

  Lactate markers: LT1, LT2 and maximal lactate steady state.

  Peter defines his zone 2, about three hours a week, as the highest power at which lactate stays under 2 mmol, roughly an RPE of 6–7. On a step test, Olav describes a flat section, then a linear rise (LT1, near maximal fat oxidation), then a near-vertical climb (LT2, close to maximal lactate steady state, or MLSS). True MLSS requires 20–30-minute efforts with lactate sampled about every five minutes. Contrary to common belief, it doesn't correspond to an RER (respiratory exchange ratio) of 1 and occurs at lower RER in longer events. For Ironman athletes, LT1 sits near 80% of VO2 max. Their fat oxidation exceeds 1 g/min even on high-carb diets.