How to Use the MOXY Monitor to Dial in Your Cycling Warm-Up and Spot Interval Fatigue

Use short, sharp efforts to drive muscle oxygen down, then ghost pedal until you hit a higher active saturation. Higher ceilings, higher floors.

The MOXY Monitor is one of the fastest ways to see what your legs are actually doing during a warm-up, a hard interval, and the recovery that follows. Unlike heart rate, which reacts slowly, muscle oxygen (SMO2) responds almost instantly to changes in intensity. That makes the MOXY Monitor invaluable for setting an optimal warm-up, pacing threshold intervals, and identifying cumulative fatigue.

Quick primer: SMO2 and THb

SMO2 is the percentage of oxygen bound in the muscle at the sensor site. Total hemoglobin (THb) reflects the local blood volume. A simple way to think about it: SMO2 is volts on a battery and THb is amps. You want to increase both so the muscles get fresh oxygen and can clear metabolic byproducts efficiently.

Why the MOXY Monitor beats heart rate alone

• SMO2 responds quickly to intensity changes, offering real-time feedback on oxygen delivery and extraction.
• It reveals local muscle dynamics that heart rate cannot, like vasoconstriction/vasodilation and the impact of body position.
• The MOXY Monitor helps you find the sweet spot: a warm-up that drives SMO2 down during short efforts and lets it rebound to a higher ceiling during recovery.

The warm-up protocol that works (practical and repeatable)

This protocol is simple, repeatable, and designed to produce progressively higher SMO2 ceilings and higher floors. It also primes monocarboxylate transporters that help convert lactate back to usable energy.

1. Ride easy for 4.5 minutes to settle into a baseline SMO2.
2. Do a 30-second “pick-me-up” at very high intensity—enough to drive SMO2 deep (in some athletes this hits the low 20s).
3. Ghost pedal (very low cadence and minimal load) for 4.5 minutes to let SMO2 rebound and plateau.
4. Repeat the cycle for 25–40 minutes depending on age, environment, and fatigue. Minimum effective time is about 22 minutes.

Watch the MOXY Monitor during the 30-second efforts and the recovery. Each time you finish a pick-me-up, the goal is to reach a slightly higher SMO2 peak than before. That tells you the legs have vasodilated and are ready for harder work.

Reading SMO2 during intervals and spotting fatigue

Three useful patterns to watch for on the MOXY Monitor:

• Rapid dive and rebound: Short high-intensity efforts should make SMO2 dive, then recovery should produce a clear rebound and a new, higher plateau.
• Threshold plateau: During sustained threshold efforts, SMO2 will often settle into a plateau. If it holds, your power is repeatable. If SMO2 trends downward, fatigue is accumulating.
• Ceiling suppression: After repeated hard efforts, the peak SMO2 during recovery may not reach earlier highs. That drop signals dehydration, cumulative fatigue, or insufficient recovery.

If you see a steady fatigue line—SMO2 declining while heart rate rises—consider lowering power by 5–7 watts to find a sustainable plateau and improve repeatability.

Practical tips for reliable MOXY Monitor readings

• Sensor placement matters. Be consistent with where you place the sensor; readings are location specific.
• Less adipose helps. Lower body fat at the sensor site improves signal quality.
• Connectivity options. The MOXY Monitor transmits on ANT+ and Bluetooth so you can see SMO2 on head units or software like PerfPro Studio.
• Body position affects SMO2. Standing often produces lower SMO2 because it’s powerful but less efficient; sitting back up can change blood flow and shift values.
• Use short efforts to probe. Thirty-second pick-ups are a great diagnostic tool to measure how low you can push SMO2 and how quickly it recovers.

How to use SMO2 targets in sessions

While exact numbers are individual, you can use SMO2 to guide intensity and readiness:

• Target deep dives during short efforts (for some athletes that’s low 20s).
• Look for progressively higher recovery peaks session to session; consistency in hitting a ceiling indicates a well-prepared muscle state.
• During threshold intervals, aim for a stable SMO2 plateau. If it drops through a set, reduce power slightly to restore repeatability.

Final coaching notes

The MOXY Monitor gives you a direct window into muscle oxygen dynamics. Use it to fine-tune warm-ups, pace long efforts, and detect accumulating fatigue earlier than heart rate alone would allow. Small adjustments—timing of a pick-me-up, a few watts here or there, consistent sensor placement—can make your intervals more productive and repeatable.

Apply these principles consistently and you’ll get clearer, actionable feedback from every warm-up and interval session. Higher ceilings and higher floors: that’s the sign your legs are ready.

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