You might already be familiar with the 5-zone training system developed by Sally Edwards in 1992. It is a great system, but it’s specifically built for endurance athletes logging steady-state miles, whereas my 7-zone training system is built for healthspan, biological age reduction, and ultimate time efficiency for regular people and those who want to explore their upper limits. The 1992 Edwards model fundamentally stops at the limits of aerobic capacity (100% MHR), completely ignoring (or being unaware of) the physiological miracles that occur in the supramaximal zones.

Researchers William Haskell and Samuel Fox developed the widely known formula for estimating Maximum Heart Rate (MHR = 220 – age). While this is accurate for more than two-thirds of the population, many people fall outside this range due to genetic factors. The formula works adequately for me, but when I was doing the sport of tower running (competitive stairwell racing in skyscrapers), I would regularly exceed my “calculated” maximum heart rate, sometimes for up to 10 minutes. This is where I stumbled upon the magical unicorn zone of VO2 max improvement.

My model goes two zones higher than Sally’s 5 zones. I found Zone 6 to be incredibly powerful, but Zone 7 to be the magical unicorn zone, offering rapid VO2 increase, mitochondrial miracles, supercompensation, fat furnace activation for 12+ hours, and much more. During and since my tower-running days, I tested the theory on many others, with consistent results showing that it develops VO2 max faster than any other method I am aware of. I also became my own “poster child” for this type of training by increasing my VO2 max from 47 to 63 in 3 months. I was able to produce similar results for others, despite traditional training “science” telling me such improvement should take 2-3 years at best. Click here for that story.

I also found the minimum effective intensity for a competitive athlete to improve their VO2 max was 80% of their Max Heart Rate (MHR), or Zone 3. For a deconditioned person, this zone would provide rapid improvements, but for a highly trained individual, it is slow improvement or maintenance. This is why I use Zone 3 as the baseline for comparing the results of the other zones; the zones above it show exponential growth, as I and others I have tested it on have experienced and verified with my Pnoe gas exchange analyzer.

Here is a breakdown of my 7 training zones, the exponential benefits (or detriments) to your VO2 max, and the metabolic after-effects. This is based on my own data from hundreds of X Gym members, my fellow tower runners, and friends who are willing to submit themselves to my Xtreme X Gym Xperiments.

Zone 7 (120% Max Heart Rate)

• VO2 Benefit: 32x the benefit of Zone 3. Just 1 minute in Zone 7 equals 32 minutes in Zone 3.

• After-Effect: Supercompensation for 12 to 36 hours.

• The Reality: Most Americans are not physically and/or mentally able to reach Zone 7. Only highly trained athletes with an elite mental ability to endure extreme suffering can ever even hope to touch this level. I would get into this zone for about half of my tower races and could sustain it for 3 minutes max on a good day, and that would typically win me that race.

Zone 6 (110% Max Heart Rate)

• VO2 Benefit: 16x the benefit of Zone 3. 1 minute here equals 16 minutes in Zone 3.

• After-Effect: EPOC for 8+ hours.

• The Reality: This is where most Americans never go. Some are able physically, but not mentally. This was my racing zone, sustainable for up to 10 minutes, and would usually place me in the top 3 in a race.

Zone 5 (100% Max Heart Rate)

• VO2 Benefit: 8x the benefit of Zone 3. 1 minute here equals 8 minutes in Zone 3.

• After-Effect: EPOC for 4+ hours.

• The Reality: This is where most Americans rarely go. This was my training zone when I was a competitive athlete, but it’s now the zone I usually “touch” once or twice during most X Gym Xardio or sprint-interval workouts. IF EVERY AMERICAN JUST MOMENTARILY “TOUCHED” ZONE 5 ONLY TWICE A WEEK, OUR COUNTRY WOULD BE THE FITTEST IN THE WORLD.

Zone 4 (90% Max Heart Rate)

• VO2 Benefit: 4x the benefit of Zone 3. Just 1 minute here equals 4 minutes in Zone 3.

• After-Effect: EPOC for 2+ hours.

• The Reality: Most Americans spend about 1% of their lives here. This is the zone I spend the most time in during every Xardio workout. As a tower runner, I felt my workout didn’t start until I was within this zone. Every zone below it was a warm-up.

Zone 3 (80% Max Heart Rate)

• VO2 Benefit: The warm-up zone. Provides VO2 maintenance but requires a minimum of 30+ minutes to very slowly improve VO2 (to a point, until it plateaus, and it will).

• The Reality: Most Americans spend about 3% of their lives here. I do not feel fatigue or benefit in this zone. When I was a tower runner, it was a complete waste of time, so I would blast through it as fast as I could.

Zone 2 (70% Max Heart Rate)

• VO2 Benefit (mostly detriment): Walking and chores. This does not maintain VO2. VO2 can improve (then plateau) in the deconditioned, but will decline in trained individuals.

• The Reality: Most Americans spend about 18% of their lives here.

Zones 0 and 1 (Resting and Sleeping Heart Rates)

• VO2 Detriment: Rapid decline. VO2 declines with age, regardless of session length.

• The Reality: Most Americans spend 78% of their lives here.

For those looking to save time, achieve ultimate muscle tone, and actively reduce their biological age, tapping into zones 4 and above through highly efficient, intense functional intervals is where the real results happen.

IMPORTANT NOTE: Get clearance from your doctor before acting on this information or anything else you learn on the internet.