In Dr. Yeoh's experience, 5 minutes of recovery is adequate between VO2 max interval blocks to allow return to performing the next block of intervals

Even though VO2 max and lactate threshold are genetically determined, most people haven't reached their genetic potential, so there is substantial room to increase and improve both metrics

The aerobic system breaks down one molecule of glucose into 36-38 molecules of ATP (the body's energy currency), while the anaerobic system only produces 2 ATP per glucose molecule, making the aerobic system approximately 18-19 times more efficient

The 30/30 Version 2 or 60/60 protocol involves 60 seconds at VO2 max speed followed by 30 seconds of moderate jog recovery, repeated until complete exhaustion

Dr. Yeoh's own VO2 max training protocol uses a 1:1 work-to-rest ratio at 10-minute intervals: 1 minute at 90-100% maximum heart rate (Zone 5) followed by 1 minute rest/cooldown, repeated 5 times for 10 minutes total, followed by 5-minute recovery phase before resuming the next interval block, continuing until complete exhaustion

Zone 2 training (60-70% of maximum heart rate) should be added to training programs because it increases mitochondrial density, which leads to improved oxygen utilization, increased fat oxidation, and enhanced lactic acid clearance

Recovery (rest periods) between interval sets is critical; a 2018 British study found that longer recovery durations facilitate higher training loads and greater training adaptations

Lactate threshold training should focus on increasing the aerobic system's ability to supply power at higher workloads, which reduces and delays the anaerobic system's contribution, thereby improving sustainable power output because the aerobic system is more efficient than anaerobic

The basic principle for improving both VO2 max and lactate threshold is interval training, and many different protocols and recommendations have proven effective for different people

VO2 max measures how efficient your cardiorespiratory system is in delivering oxygen to muscles and how efficient muscles are in using that oxygen

Interval training is considered the key method to improve both VO2 max and lactate threshold, though there is no universal consensus on the best specific protocol

The 30/30 Version 1 protocol involves 30 seconds at VO2 max speed followed by 30 seconds of moderate jog recovery; Dr. Billat found that during the moderate jog phase, metabolism remains ramped up near VO2 max, resulting in better utilization and more efficient use of time compared to classic protocol

For lactate threshold training, Dr. Yeoh uses either a 3:1 or 4:1 work-to-rest ratio with exercises maintained in Zone 4 (80-90% of maximum heart rate) to adapt the body to dealing with increased lactic acid and to efficiently clear lactic acid

The VO2 max equation is: VO2 max = cardiac output × arterial-venous oxygen difference in muscles, which can be rearranged as VO2 max = stroke volume × heart rate × arterial-venous oxygen difference

Three critical factors to consider when developing interval training protocols are: (1) the intensity of the interval, (2) the number of intervals performed, and (3) the rest period between each interval

Lactic acid is a byproduct of anaerobic glucose metabolism, and as lactic acid accumulates during intense exercise, fatigue increases; anaerobic metabolism is useful primarily for short bursts of energy like the final meters of a marathon or powerlifting

Both VO2 max and lactate threshold are limited and affected by genetics, age, and sex, making it difficult to compare values between individuals; athletes should establish their own baseline as a reference point rather than comparing to others

As fitness level increases from VO2 max training, athletes can increase the duration of their interval training time blocks

A 2000 University of Tennessee study found that VO2 max improvements with training were primarily due to increases in cardiac output (oxygen delivery) rather than increases in oxygen utilization by muscles, meaning the cardiovascular system contributes 70-85% of VO2 max improvement

Dr. Veronique Billat developed velocity at VO2 max (vVO2 max)—the speed at which someone reaches maximum aerobic capacity—as a better predictor of VO2 max improvement, lactate threshold improvement, and endurance performance than absolute VO2 max values