How Fit Are You? 3 Ways to Measure Without Focusing on Weight

“As you get more fit, you’re going to see that the heart rate comes down at the same intensity of exercise,” said Christopher Lundstrom, a lecturer in sport and exercise science at the University of Minnesota. “So that heart rate is certainly a good measure and an easy measure that anybody could take.”

Another heart rate-related metric to track is variability, which can be assessed using more advanced smartwatches or fitness trackers. Heart rate variability measures how much your heart rate fluctuates from one beat to the next, and more variability is considered a sign of good cardiovascular health.

While we often think of the heart as a metronome, beating at a steady pace, there are actually small variations in the length of each beat and the time between them. “At rest, very low heart rate variability shows that the heart is just doing all it can to keep up,” Dr. Lundstrom said. “The more fit you are, the more your heart has the ability to adapt and adjust really quickly to changing demands.”

VO2 max is the most precise assessment of cardio-respiratory health, measuring the capacity of the heart and lungs to take in oxygen, distribute it throughout the body and convert it into cellular energy. VO2 max is typically performed in a lab and requires special equipment that most people don’t have access to, but there are at-home tests — like the three-minute step test — that can provide a rough estimate.

Physical fitness can also be defined by “performance metrics and maximizing strength, power, endurance,” Dr. Lundstrom said. Setting — and hitting — workout targets is perhaps the most tangible strategy to track your strength and endurance progress.