Heart Rate and Energy Expenditure Validity of Garmin Instinct Devices During Hiking Outdoors with and without Trekking Poles: A Pilot Study

ACSM has again named wearable technology the top fitness trend for 2024. Yet, the validity of wrist-worn devices for measuring average/maximal heart rate (HR) and estimating energy expenditure (EE) during outdoor hiking with and without trekking poles is unknown. PURPOSE: To determine the concurrent validity of identical Garmin Instinct devices to record valid measures of average and maximal HR as well as estimated EE during outdoor hiking with no poles, 1 or 2 trekking poles. METHODS: 11 (n=6 males, n=5 females, aged 20-39 yrs) adults randomly completed 3 pole conditions (no poles, 1 or 2 poles) during an ~10 min. uphill and ~10 min. downhill hike on the same trail. Two Garmin Instinct devices were evaluated, along with the Polar H10 chest strap (average/maximal HR criterion) and Cosmed K5 portable metabolic cart (EE criterion). Data were analyzed for validity (Mean Absolute Percent Error [MAPE] and Lin’s Concordance Coefficient [CCC]), with predetermined thresholds of MAPE<10% and CCC>0.70. A two-way ANOVA was used to determine differences between identical Garmin devices, p<0.05 RESULTS: There were no effects between Instinct #1 or #2 for average HR (p=0.09) or maximal HR (p=0.23), yet there was a main effect (p=0.01) for Instinct #1 being higher than #2 for EE (3 condition average: 179.8±35.4 or 165.2±21.8 kcals). Garmin Instinct #1 and #2 were valid for average HR (MAPE: 1.4% & 1.5%; CCC: 0.98 & 0.98) and max. HR (MAPE: 1.6% & 1.6%; CCC: 0.95 & 0.95) for the no poles condition. Contrarily, Garmin Instinct #1 was not valid during the 1 and 2 poles conditions for average HR (MAPE: 4.4% & 4.3%; CCC: 0.25 & 0.62) or max. HR (MAPE: 4.6% & 4.2%; CCC: 0.06 & 0.45), and Garmin Instinct #2 was not valid for max. HR in the 1 pole condition (MAPE: 3.4%; CCC: 0.55), but was valid for 1 and 2 poles for average HR (MAPE: 0.9% & 0.9%; CCC: 0.99 & 0.99) and 2 poles for max. HR (MAPE: 1.4%; CCC: 0.95). Both Garmin Instinct #1 and #2 were not valid for measuring EE in the no pole (MAPE: 18.2% & 15.6%; CCC: 0.40 & 0.32), 1 pole (MAPE: 19.6% & 16.1%; CCC: 0.33 & 0.28), or 2 pole (MAPE: 14.9% & 16.1%; CCC: 0.57 & 0.28) conditions. CONCLUSIONS: There is some validity for HR measurements during hiking with Garmin Instinct devices, but the accuracy can be impacted by trekking pole condition. There are also discrepancies between devices, and these devices should not be used to estimate EE.