Metabolic Exercise Testing (MET)

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  • Metabolic Exercise Testing (MET) uses a machine, sensors, and a mask to measure oxygen consumed and carbon dioxide produced while exercising from low to high intensity.

  • VO2 max: the maximum amount of oxygen your body can use for energy.

    Ventilatory Thresold 1 (VT1): commonly referred to as your aerobic threshold. This correspondes to your long distance endurance capacity.

    Ventilatory Theshold 2 (VT2): commonly referred to as your anaerobic threshold and corresponds with your lactate threshold and functional threshold power (FTP).

    Metabolic Flexibility: the ability for your body to efficiently use both fat and carbohydrates for fuel and to switch between these based on demand and availability.

  • Everyone: your VO2 max is a strong predictor of your health, likelihood of dying, and ability to perform tasks as we age.

    Training efficiency: Metabolic testing allows individualized training zones based on your actual physiology rather than population estimates. This helps ensure your easy days are easy enough and your hard days are hard enough—reducing wasted training. Most recreational athletes unintentionally train in the wrong zone; metabolic thresholds reduce this mismatch.

    Athletes: VT1, VT2, and VO2 max strongly predict athletic performance making it invaluable to athletes, whether recreational or competitive.

    Weight Loss: knowing how many calories you are burning, what is being burned (fat versus carbohydrates) guides nutrition and expenditure.

  • MET testing is performed at TMD Health on either a stationary bicycle or treadmill while wearing a mask on your face. It begins with an easy warm up and then increases in difficulty every minute until high intensity is reached.

  • $250 for a single test

  • Resting/Basal Metabolic Rate (RMR): the number of calories you burn at rest

    Test involves laying still and breathing into a tube.

    Cost $50

Training with MET data

The 5 training zones that are commonly discussed are based on percentages of your maximum heart rate (HRmax). HRmax is often calculated based on the formula 220 minus your age. It then describes: Zone 1 (50-60%) for recovery/warm-up, Zone 2 (60-70%) for aerobic base/fat burning, Zone 3 (70-80%) for moderate endurance/efficiency, Zone 4 (80-90%) for hard threshold training (anaerobic), and Zone 5 (90-100%) for maximum effort/speed intervals.

This system relies on calculations based on population averages but individuals vary quite a bit in reality.

At TMD Health, we prefer the 3-zone model because it is based on what is happening physiologically, which is what we are trying to manipulate, improve, and adapt when we are training.

How this data can impact your training:

Aerobic Base Workouts (i.e. Training below VT1):

  • ↑ Mitochondrial density

  • ↑ Capillary density

  • ↑ Fat oxidation capacity

  • ↑ Lactate clearance at low intensities

  • ↓ Sympathetic stress

  • High volume tolerance

This raises VT1 indirectly by:

  • Improving oxidative capacity

  • Delaying reliance on glycolysis

  • Improving economy at subthreshold paces

Threshold Development Work outs (i.e. Training slightly above VT1)

  • ↑ Lactate transport (MCT-1, MCT-4)

  • ↑ Buffering capacity

  • ↑ Mitochondrial enzyme activity under stress

  • ↑ Fractional utilization of VO₂ max

  • Improved tolerance of “steady hard” pace

This raises VT1 more directly, because:

  • The body adapts to handling lactate at higher workloads

  • Ventilatory control shifts rightward = you feel less out of breath despite higher CO2 levels.  Also improves respiratory efficiency. 

  • The same metabolic stress occurs at a higher absolute pace

VO2 max workouts (i.e. Training high end Zone 3)

  • Increased stroke volume and cardiac output

  • Reduced resting blood pressure/heart rate

  • Increases mitochondrial and capillary density

  • Increases blood volume and hemoglobin

  • Also improves lactate transport, buffering capacity, and fractional utilization of VO2 max

How this generates performance outcomes

Raising VT1 improves:

  • Marathon pace

  • Ironman pace

  • Ultra-endurance durability

  • Long-course efficiency

Raising VT2 improves:

  • 10K pace

  • Half marathon pace

  • Time trial performance

Raising VO₂ max improves:

  • Shorter races (5k)

  • High-end ceiling – cycling time trials, rowing, cross country skiing,…

  • Team sports that involve bursts of high intensity – higher VO2 max allows for faster recovery between and more resilience for repeated bursts

  • Overall headroom

  • Has the most data for health, longevity, and all-cause mortality reduction

How this guides recovery

  • Exercise is a form of stress. It is the adaptation to this stress during periods of recovery that results in the performance gains.

  • Recovery requires energy. Your body has to spend energy to refill the tank (replete glycogen), repair and grow

  • Inadequate recovery in response to stress results in loss of energy and motivation.

  • If you train too much above VT1, you:

    • Accumulate fatigue

    • Suppress total training volume

    • Drift into chronic “gray zone” training (between VT1 and VT2)

    • Risk stagnation/plateau or regression if recovery debt gets too big

  • We use a combination of MET testing, Heart Rate Variability (HRV), Sleep duration/quality, and subjective soreness to generate recovery scores that find the ideal balance between stress and recovery to efficiently maximize progress and avoid burnout.

  • What you do outside your workouts matters. Sleep, nutrition, recovery workouts, mobility are all paramount.