Estimation of energy expenditure of Nordic walking: a crossover trial

Abstract

Background: Nordic walking (NW) requires more energy compared with conventional walking (W). However, the metabolic equation for NW has not been reported. Therefore, this study aimed to characterize responses in oxygen uptake, minute ventilation, heart rate, systolic blood pressure, and surface electromyography of the upper and lower limb muscles during NW and W and develop a metabolic equation for energy expenditure (E, mL·kg^{- 1}·min^{- 1}) of NW.

Methods: This study was performed in a randomized, controlled, crossover design to test the energy expenditure during NW and W. Fifteen healthy young men were enrolled (aged 23.7 ± 3.0 years). All participants performed two randomly ordered walking tests (NW and W) on a treadmill at a predetermined stepwise incremental walking speed (3-5 km·h^{- 1}) and grade (0-7%). The oxygen uptake, minute ventilation, heart rate, systolic blood pressure, and surface electromyography signals of the three upper limb muscles and three lower limb muscles in their right body were recorded and compared between NW and W using paired-t test. Multiple linear regression analysis was used to draw estimation of E during W and NW.

Results: Oxygen uptake (+ 15.8%), minute ventilation (+ 17.0%), heart rate (+ 8.4%), and systolic blood pressure (+ 7.7%) were higher in NW than in W (P < .05). NW resulted in increased muscle activity in all of the upper limb muscles (P < .05). In the lower limb, surface electromyography activities in two of the three lower limb muscles were increased in NW than in W only during level walking (P < .05). Energy expenditure during W and NW was estimated as follows: E_NW = 6.1 + 0.09 × speed + 1.19 × speed × grade and E_W = 4.4 + 0.09 × speed + 1.20 × speed × grade.

Conclusion: NW showed higher work intensity than W, with an oxygen consumption difference of 1.7 mL·kg^{- 1}·min^{- 1}. The coefficients were not different between the two walking methods. NW involved more muscles of the upper body than W.

Keywords: Electromyography; Energy metabolism; Heart rate; Nordic walking; Oxygen consumption.