Walk Smarter

Unlocking Fitness and Injury Insights with Apple Watch Metrics

Health and wellness wearables are everywhere these days, tracking everything from heart rate to sleep to steps. If you’re curious about a health stat, there’s probably a gadget for it. Earlier this year, I began wearing an Apple Watch for my daily routine and stumbled across some fascinating musculoskeletal metrics that can mean a lot as we age. These seven gait-specific metrics—walking heart rate, walking asymmetry, step length, walking speed, double support time, stair speed, and the 6-minute walk test—are backed by science and paint a clear picture of your mobility. Most of these metrics can be measured using just an iPhone carried near the waist (e.g., in a pocket). However, stair speed and the 6-minute walk test typically require an Apple Watch. These metrics are studied mostly for fall risk in older folks, but even if you’re in your 40s and 50s, they’re a goldmine for gauging fitness, spotting injury recovery gaps, or dodging future issues. For instance, a wonky step length or sluggish walking speed might hint at weakness you can fix now.

Apple selected these metrics based on extensive research, as they are widely studied in gait and fitness analysis. However, not all metrics discussed below are standardized across studies. The charts below were generated using an AI engine that drew data from various databases and journals. Consider these charts as general guidelines rather than definitive assessments of your fitness or fall risk.

Walking Heart Rate

Your walking heart rate is a general measure of endurance, trackable with an iPhone or Apple Watch. An elevated heart rate while walking indicates poor aerobic endurance, and excessive exertion during walking increases fall likelihood by impairing balance. A walking heart rate exceeding 120 bpm in someone aged 60 years indicates a doubling of fall odds. In someone in their 40s, walking heart rate is better used as a fitness proxy. A 120 bpm walking heart rate at this age suggests poor fitness and possibly mobility restrictions, such as an injury.

Walking Heart Rate by Age

*For ages 10–19, heart rates are higher due to higher MHR, and children’s walking pace may vary widely.

*Data aligns with exercise guidelines from the American Heart Assciation.

Walking Asymmetry

Walking asymmetry, measured by comparing the speed of steps taken with your left versus right foot, can be captured with an iPhone carried in a pocket or an Apple Watch. For a 60-year-old, an asymmetry exceeding 8% is a strong predictor of a fall. A study of runners and rehab patients aged 40+ found that gait asymmetry exceeding 5% was associated with a 1.5–2 times higher risk of musculoskeletal injuries in the hip and knee due to uneven joint loading.

Walking Asymmetry by Age

*Asymmetry typically falls between younger and older adults, estimated at 10–17%, reflecting gradual muscle and joint changes.

*Data on walking asymmetry by age is not standardized. Chart data based on a study cited in Medicine & Science in Sports & Exercise.

Step Length

Short steps indicate a cautious gait and/or musculoskeletal weakness, measurable with an iPhone or Apple Watch. In 60-year-old men or women of average height, a step length of less than 19.7 inches indicates a doubling of fall risk. At any age, when rehabbing from an injury, the goal is to achieve an average step length of 25 inches or more, as this aligns with the step length of healthy adults and indicates restored function.

Step Length by Age

*Exact step lengths vary by height, gender, and walking speed, but these ranges reflect averages for adults of typical height (160–180 cm) walking at a normal pace (1.2–1.4 m/s). For children, ranges are adjusted for smaller stature.

Walking Speed

Slower walking speeds, measured in meters per second, are a top fall predictor and can be tracked with an iPhone or Apple Watch. A 2016 meta-analysis (adults 65+ years old) found speeds below 0.9 m/s increase fall odds by 1.7 times. Slow speeds also signal weakness, raising musculoskeletal injury risk. Speeds below 1.2 m/s in middle-aged adults (40–59) suggest incomplete recovery (e.g., post-knee replacement or ACL repair) and potential for overexertion injuries due to compensatory gait patterns.

Walking Speed by Age

*Ranges align with studies from Journal of Gerontology and biomechanics data for typical walking conditions.

Double Support Time

Double support time measures the time spent with both feet on the ground while walking, expressed as a percentage of your gait cycle, and is trackable with an iPhone or Apple Watch, though iPhone accuracy may be less precise. Higher double support time indicates gait instability, as more time with both feet on the ground suggests balance issues. A 2015 study of seniors over 65 years old found that double support time exceeding 35% doubles fall odds.

Double Support Time by Age

*Ranges align with gait analysis research, including Journal of Biomechanics and studies on age-related gait changes.

Stair Speed

A 2002 study (Journals of Gerontology) found that slow stair speed, best measured with an Apple Watch due to its barometer detecting vertical movement, predicts falls and mobility decline. In rehab, slow speeds increase joint injury risk. A risk stratification found that a stair speed of less than 0.8 ft/s increases fall odds by 1.5 times, placing individuals at high risk for falls.

*Derived from gait studies (e.g., Journal of Gerontology, Gait & Posture).

6-Minute Walk Test

This is an estimate of how far you can walk in six minutes, measured in meters, typically requiring an Apple Watch for accuracy due to continuous wrist-based monitoring. Lower scores (e.g., below 400 m for ages 70+) indicate poor endurance and mobility, a strong fall predictor. A 2019 study found that scores below 350 m triple fall risk. This metric can be a valuable tracking tool for general fitness in younger populations. The average 40-year-old should be able to walk over 610 meters. For younger populations, lower scores may indicate poor fitness, an existing injury, or mobility restrictions.

6-Minute Walk Test by Age

*Ranges align with studies in American Journal of Respiratory and Critical Care Medicine and 6MWT normative databases.

Why These Metrics Matter

Wearable devices like the Apple Watch and iPhone track gait metrics that provide insights into musculoskeletal health. These metrics are equally valuable for younger individuals to assess fitness, monitor injury recovery, and prevent mobility issues. Tracking them over time can reveal declines in aerobic or musculoskeletal health, such as pain-related compensatory patterns that may lead to injuries. Comparing results to age-specific norms helps guide decisions to consult professionals or implement targeted interventions, like strength or balance training, to optimize mobility and reduce injury risk.

Curious about your mobility or injury risk? How do you stack up against your cohorts? Schedule a remote or email-based physical therapy consultation to analyze your Apple Watch or iPhone gait metrics. Complete our brief questionnaire to provide lifestyle and fitness context, such as activity levels or injury history, enhancing our assessment. These science-backed metrics reveal fitness, recovery gaps, or weaknesses, even in your 40s or 50s. For example, gait asymmetry over 5% may increase hip or knee strain, or a step length below 25 inches could signal poor recovery from previous rehabs. Share your data, and we’ll craft a personalized exercise, mobility, and recovery plan to boost strength, balance, and mobility, keeping you moving confidently.