Cycling Dynamics and Physiological Measurements

By monitoring key aspects of your cycling and fitness progress, you get a better look at your current performance level and what you need to do to keep up the good work or continue improving. Select Garmin devices collect data while you ride in order to bring you these cycling metrics and physiological measurements. It’s worth noting that some of these metrics need additional sensors such as power and heart rate. If your device is showing you stats, but you want to know more about what they mean, then you’ve come to the right place. What can you do with this calculated information? That’s up to you, but we’ve got some suggestions.

Physiological Measurements

VO2 Max

An Edge device screen showing VO2 max. Your VO2 max score is the key to seeing, understanding and, more importantly, managing your personal fitness level. On a technical level, it describes the maximum rate at which you can bring oxygen into your body, transport it to your muscles and use it for efficient aerobic energy production. On a personal level, it is a remarkable and versatile tool with a variety of health and performance implications.

When it comes to understanding your VO2 max score, it’s easy to remember that low VO2 max scores represent poor fitness levels, and higher VO2 max scores indicate greater performance capacity. Like most aspects relating to physical performance, there is a genetic dimension to how efficiently your body uses oxygen and, by extension, your VO2 max range. That said, your VO2 max score is dynamic, and it reacts to how you live and train. With the right approach, practically everyone can improve their VO2 max score.

The people least likely to be able to improve their VO2 max are elite athletes, because they are already in excellent shape. This is great news for everyone else.

Studies have shown that being more active can make you happier and live longer. VO2 max is a key metric used to study and verify this from a scientific perspective. If you’re looking to improve, your device also offers the tools you need to get things headed in the right direction.

For those interested in performance, VO2 max can be used in a slightly different way. The more oxygen your body can use during exercise, the more power you can generate and, therefore, the faster you can ride.

Power and heart rate data is needed to record cycling VO2 max.

Tips for Cycling VO2 Estimates

The success and accuracy of the VO2 max calculation improves when your ride is a sustained and moderately hard effort and where heart rate and power are not highly variable. During your 20 minute ride:

  • Try to maintain your heart rate at greater than 70% of your maximum heart rate
  • Try to maintain a fairly constant power output
  • Avoid rolling terrain
  • Avoid riding in groups where there is a lot of drafting

Performance Condition

A graph showing performance condition over the course of a ride.

An Edge device screen showing VO2 max. For a real-time assessment of your current ability to perform, look at your performance condition. During the first 6 to 20 minutes of your ride, this metric analyzes power, heart rate and heart rate variability. The resulting number is a real-time assessment of the deviation from your baseline VO2 max, with each point on the scale representing about 1% of your VO2 max. The higher the number, the better you can expect to perform. Keep in mind that your results may vary a bit during your first few rides with a new device since it’s still learning your fitness level. This will stabilize, and checking your performance condition will become a reliable day-to-day indicator of your capability.

In addition to the alert during the first part of your ride, you can add performance condition as a data field to your training screens, and keep an eye on it as your ride unfolds. The value may move around slightly as you encounter hills or strong winds, but it will trend down once you have been going hard for a while and the ride starts to take a toll on you. This is an objective way to keep an eye on how your ability to perform is or isn’t declining as you go, because it’s telling you if your body is working harder than normal to ride at your current power output. So, performance condition can give you a bit of an early warning before you “bonk.”

Recovery Time

An Edge device screen showing VO2 max. Recovery is a critical, but often overlooked, portion of the training process. The recovery period is marked by adaptation of your body in response to training and the replenishment of vital resources. In fact, insufficient recovery can lead to entirely missing out on gains in fitness and performance. Keeping track of your recovery levels will reveal when training hard will be beneficial and ensure your work is rewarded with the results you expect. You gain the ability to update and optimize your training programs with confidence.

After each ride, your device reveals the number of hours before you will be back near 100% and capable of performing a hard ride. Provided by Firstbeat, the calculation is produced and personalized using a unique digital model of your physiology. It utilizes a combination of the session’s training effect score, performance and fitness level assessments performed during the session and the number of hours of recovery time remaining on your clock at the start of your ride.

Recovery time ranges up to 4 days.

For best results, it’s beneficial to first go for several rides with your device in order for it to accurately learn your overall fitness level. Once this is established, subsequent recovery time results may be more accurate.

Functional Threshold Power (FTP)

A graph showing lactate threshold at 90% of an athlete’s maximum heart rate.

Your functional threshold represents the maximum power output you can sustain for 1 hour. Your FTP estimate will form the basis for your personalized power zones and for most power-based training plans.

Compatible Edge® bike computers can detect your functional threshold either through a guided ride or automatically during a normal ride. Either way, by gathering heart rate data across a range of power outputs, the device will estimate your threshold in terms of power output. You will find your FTP estimate improves over time as your device learns your overall fitness level. Your Edge device also shows your FTP in relation to your weight as a watts/kg value and displays it on a simple-to-follow rainbow gauge. This allows you to very quickly compare your own power to weight ratio against riders of different sizes.

Tips for Getting your Functional Threshold Power:

Guided Test:

  • Using HR and power data, we take you through a warmup, followed by a gradual increase of targeted effort in 3 to 4 minute increments over a period of 15 to 20 minutes.
  • Based on your HR response to the increasing power effort, we calculate your FTP value.
  • You have the option to accept or reject this value. If you accept, your power zones will automatically recalculate based on the new value.
  • It is recommended that this test is performed on a road with constant gradient or on an indoor trainer.

Auto FTP Detection:

  • If you set a personal 20-minute average power record, and if 95% of this value exceeds your current FTP estimate, we will prompt you to accept a new FTP value.
  • Again, you have the option to accept or reject this value.

HRV Stress Test

If you’re wondering whether your body is ready for a hard ride or in need of a lighter effort, it might be time to check your stress score. When you’re fresh and rested inside and out, you’re better able to absorb the training effect from a tough ride. However, the same hard ride can be counterproductive if you’re tired or on the verge of overtraining. Your stress score is calculated during a 3-minute test during which your heart rate variability (HRV) is analyzed. The resulting stress score is displayed as a number from 0 to 100, with a lower number indicating a lower stress state. This measurement helps you assess what level of activity your body is ready for. More accurate results are gathered by taking the test at the same time and under the same conditions every day (recommended prior to the ride, not after). This also helps you get a feel for your own day-to-day and week-to-week variations.

You are required to stand to take the HRV stress test, because that makes the test more sensitive to low and medium levels of stress. When you are lying down, moderate levels of stress may not be revealed, but standing puts a slight load on your cardiovascular system. That load causes a meaningful drop in HRV when you have a moderate amount of stress compared to very low stress.

Cycling Dynamics

Image of an Edge 1000 cycling device with a cycling dynamics screen. Whether you ride for competition, exploration or simply for fun, Garmin can help you gather the data to prove how hard you worked or aid you in improving your form. That’s because select devices, such as our dual-sensing Garmin Vector™ pedal-based power meter, let you access cycling dynamics. Cycling dynamics refers to a suite of advanced metrics designed to give comprehensive insight into how you’re riding and how your performance changes based on variables such as position, bike setup, ride duration and more. With cycling dynamics – cyclists, coaches, bike fitters and even physical therapists can analyze individual data for precise prescriptive actions.

Seated/Standing Position

A graphic depicting seated vs standing position on a bicycle. You likely have a unique preference for position on the bike during climbs and sprints. Vector can detect and flag riding position (seated or standing) during a ride by comparing forces applied to the pedals. Your compatible Edge cycling computer will then display current position, summaries of how often and how long you have been in the position and power data, all in real time.

After your ride, you can upload your data to Garmin Connect™ online fitness community. There you can view each position, associated cadence and speed, and you can compare time spent seated vs. standing. Even learn how a certain position affects your power output, and analyze climbs and sprints. This detailed data gives you a dialed-in look at your ride and can be useful when determining position effectiveness and identifying tendencies to move positions during particular moments of a ride.

Power Phase (PP)

A graphic illustrating power phase during a pedal stroke. Power phase provides a valuable description of how you’re currently producing power in a pedal stroke. Vector detects where the leg is generating positive torque in a pedal stroke and where the greatest concentration of positive torque occurs. It also senses the angle at which these forces begin and end and where your concentration of power is produced. If you’re using the dual-sensing Vector power meter, you get to take your analysis one step further and see if there are differences between the left and right leg.

Power phase is measured as a combination of degrees and arc length, with 0 degrees representing the 12 o’clock position and 180 degrees representing the 6 o’clock position. The length of the power phase is measured by the difference between the starting and end angles. For example, a power phase starting angle of 5 degrees and a power phase end angle of 220 degrees would represent a power phase arc length of 215 degrees. With dual-sensing pedals, this information is provided for both your left and right legs. Then you can view where the majority of power is produced using the peak power phase metric (PPP). The default setting is for peak power phase to represent 50% of the power output, but this can be adjusted up or down depending on your preference.

You can view power phase metrics displayed graphically on Edge devices and on Garmin Connect. This makes it easier for you to visualize your pedal stroke.

Platform Center Offset (PCO)

An image displaying platform center offset on a pedal. The PCO measurement is calculated by identifying how force is distributed across the pedal platform during the pedal stroke. That means you can view and evaluate where force is applied relative to the center of the pedal platform and what the PCO distribution is over a given period of time. Analyzing this data can help you determine proper bike fit and cleat position. It may also be helpful in preventing injury and rehabilitation.

PCO is measured in millimeters. Positive values (e.g., +6 mm) indicate increased force toward the outside of the pedal, while negative values (e.g., -4 mm) indicate increased force toward the inside of the pedal. You can view this information in graph form on your Edge device. The red line indicates the current 10-second average value and the blue line represents the average for the previous 30 seconds.

Right/Left Balance

An image showing the power output difference between a left and right leg. The dual-sensing Vector pedals are not only able to measure your combined power output, they can also separate left-leg from right-leg power to let you know if 1 leg is producing more power than the other. In other words, how symmetrically are you pedaling?

Studies show that a large imbalance between the left and right leg force production can cause premature fatigue and even put you at increased risk for injury. That’s why it’s good to know if there’s significant asymmetry, so you can work on improving it. Symmetry means both legs are working equally hard, giving you better efficiency.