Reliability and validity of the Tritrac-R3D accelerometer during backpacking: A case study

This study investigated the utility of the Tritrac-R3D accelerometer as a r eliable and valid instrument in the quantification of physical activity whi le backpacking in the field and to evaluate heart-rate responses and oxygen consumption to assess the feasibility of using the Tritrac-R3D to estimate caloric expenditure. Two 7-day backpacking expeditions were conducted in t wo consecutive years by a single subject at Grand Canyon National Park. Ari zona. The average hiking he-art rate ranged from 60% to 77% HRmax during th e expeditions. The average rate of estimated caloric cost ranged from 6.8 t o 11.7 kcals . min.(-1) (equivalent to 408 to -702 kcals . hr.(-1)), indica ting a relatively moderate to high level of exertion. The Tritrac had adequ ate consistency and reliability in the field between the two expeditions in recorded activity counts. The Tritrac underestimated caloric expenditure d uring backpacking with changes in terrain, and hiking speed contributed to even greater disparity in accuracy.