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April 19, 2024

Some of the most well-known metrics for your fitness are VO2Max and FTP. These metrics are mostly used to measure your fitness over time and to enable you to make effective training plans. However, their significance extends beyond training plans, influencing your body’s metabolism during workouts.

During workouts your body uses several energy systems at the same time to account for its energy expenditure, mainly body fats and carbohydrates. While fat reserves are ample, carbohydrate stores are limited, emphasizing the importance of replenishment during intense workouts.

Why your fitness matters

The intensity of your workout directly correlates with the percentage of carbohydrates burned. Accurately assessing your fitness prevents misjudgments in carbohydrate expenditure,

Example of an athlete of 70 kg:
On the left VO2Max = 48, FTP = 220W. On the right: VO2Max – 60, FTP = 330

How to measure your fitness



This metric denotes your body’s maximum oxygen consumption during exercise. This metric can be measured for different types of sports. The most reliable measurement is a lab test but devices like head units and smartwatches such as from Garmin can nowadays estimate it quite accurately for you, based on your heart rate and/or power. Browse through the companion app of your device and you might just find your value.


FTP is a cycling metric that stands for Functional Threshold Power. It represents an approximation of your maximal lactate steady state (MLSS), measured in watts. In common language it is referred to as the maximum amount of wattage you can sustain pushing for around 1 hour. In cycling training, FTP is used to determine power zones used in training, and help give athletes a point of reference to help with pacing.

This is how you can measure your FTP:

  • Easy: devices like head units and smartwatches such as from Garmin can estimate it easily for you as long as you use a power sensor. Be aware it can seriously underestimate your FTP if you trained below your maximum capabilities.
  • Solid: run an FTP test protocol. Indoor cycling computers usually have a powersensor. You can take a specific ‘FTP test’ with is usually 20 minutes long such as on Zwift or any other platform.


Fill in your fitness in EatMyRide

EatMyRide needs either your VO2Max or FTP. If you train by heart rate you also need to set your heart rate zones for the most accurate results. Many devices such as from Garmin nowadays track your VO2Max and FTP.

How to see the impact of my fitness on my metabolism

Go to Profile > Personal > Cycling to see the carbohydrate and body fat burn at different exercise intensities. If you change your fitness metrics, the metabolism estimation will change as well. The metabolism values are used to calculate your burn and intake in the EatMyRide mobile app. Also the Carbohydrate Burn/Intake Balancer datafield for Garmin uses these values to show your burn and intake in real time.