Reliability and Validity of Garmin Forerunner 735XT for Measuring Running Dynamics In-field
Authors
Nielsen, Michael Skovsgaard ; Andersen, Christian Hauge
Term
4. semester
Education
Publication year
2017
Submitted on
2017-06-07
Pages
10
Abstract
Baggrund: Nye aktivitetsure kan måle løbedynamik, men de skal være pålidelige og gyldige i virkelige omgivelser for at kunne bruges til realtidsfeedback, genoptræning af løbestil og forebyggelse af skader. Denne studie undersøgte Garmin Forerunner 735XT med HRM-Run (GFR) ved at sammenligne fire mål: lodret oscillation (hvor meget kroppen bevæger sig op og ned), jordkontakttid (den tid foden er i kontakt med underlaget), skridtlængde (afstand pr. skridt) og kadence (skridt pr. minut) med fuld kropsbevægelse målt af bårne bevægelsessensorer (inertimåleenheder, IMU’er). Metode: 24 rekreativt aktive deltagere løb på en lige strækning ved tre hastigheder (10, 12 og 14 km/t). For hver hastighed blev der indsamlet to minutters data, og der var to basismålinger for at teste gentagelighed. GFR registrerede løbedynamik, mens Xsens MVN Link IMU’er indsamlede 3D-bevægelsesdata. Pålidelighed (gentagelighed) og gyldighed (overensstemmelse med IMU-målinger) blev vurderet med standardmetoder, herunder Intraclass Correlation Coefficient (ICC) og Bland-Altman-analyse, som vurderer henholdsvis enighed og systematiske forskelle. Resultater: GFR viste høj pålidelighed mellem basismålinger (høj ICC). Sammenlignet med IMU-målinger var gyldigheden god for lodret oscillation, skridtlængde og kadence (god overensstemmelse), mens jordkontakttid havde moderat overensstemmelse. Bland-Altman-analysen viste, at GFR havde en tendens til at overvurdere lodret oscillation og undervurdere jordkontakttid. Konklusion: Garmin Forerunner 735XT med HRM-Run giver generelt pålidelige og gyldige feltmålinger af løbedynamik. Dog bør jordkontakttid og lodret oscillation tolkes med forsigtighed på grund af systematiske afvigelser.
Background: New consumer wearables can measure running form, but they must be reliable and valid in real-world use to support real-time feedback, gait retraining, and injury prevention. This study tested the Garmin Forerunner 735XT paired with the HRM-Run (GFR) by comparing four metrics—vertical oscillation (how much the body moves up and down), ground contact time (time the foot spends on the ground), step length (distance per step), and cadence (steps per minute)—against full-body motion measured with wearable inertial sensors (IMUs). Methods: Twenty-four recreationally active adults ran on a straight path at three speeds (10, 12, and 14 km/h). Two minutes of data were collected at each speed, with two baseline trials to assess repeatability. Running dynamics were recorded by the GFR, and 3D motion was captured by Xsens MVN Link IMUs. Reliability (repeatability) and validity (agreement with IMU-based measures) were evaluated using standard approaches, including the Intraclass Correlation Coefficient (ICC) and Bland-Altman analysis, which assess agreement and systematic bias. Results: The GFR showed high reliability between baseline trials (high ICC). Compared with IMU-based measurements, validity was good for vertical oscillation, step length, and cadence (good agreement), and moderate for ground contact time. Bland-Altman analysis indicated that the GFR tended to overestimate vertical oscillation and underestimate ground contact time. Conclusion: The Garmin Forerunner 735XT with HRM-Run provides generally reliable and valid field measurements of running dynamics. However, ground contact time and vertical oscillation should be interpreted with caution due to systematic bias.
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