In the present study, comparing e-biking to conventional bicycling on two different routes simulating relevant cycling to work options, e-biking was faster and less intensive than conventional bicycling, especially on the hilly route. However, 95% of time spent biking, both for e-bike and conventional bike, were considered to be MVPA.

E-biking were faster than conventional bicycling, and reduced the time cycling with almost 30% in the hilly route. These results support the findings from previous studies regarding lower trip duration with an E-bike compared with a conventional bicycle [19, 30, 31], due to a higher speed. Gojanovic et al. [19] observed that when riding an E-bike, speed was on average 6 km/h higher than on a conventional bicycle, on the same route, similar to the 5 km/t in the present study. Furthermore, observational studies found on average 2 km/h higher speed in E-bike cyclists compared with individuals travelling by conventional bicycles [30, 31]. Schleinitz et al. [30] also illustrated that age, road gradient, and bicycle infrastructure may influence differences in cycling speed and trip duration between E-bikes and conventional bicycles.

E-biking was less intense than conventional bicycling, both relative (a 17% lower \( \overset{.}{\mathrm{V}}{\mathrm{O}}_2 \max \)) and absolute (36% lower time spent in VPA). To the authors´ knowledge, in only one published study exercise intensity has been measured relative to cardiorespiratory fitness when riding an E-bike and a conventional bicycle. Gojanovic et al. [19] observed 55% of \( \overset{.}{\mathrm{V}}{\mathrm{O}}_2 \max \) when subjects cycled on an E-bike, and 72% of \( \overset{.}{\mathrm{V}}{\mathrm{O}}_2 \max \) during conventional bicycling, and slightly higher compared to the 51 and 58% in present study. In the present study, when the participants cycled on the conventional bicycle, the difference between the hilly and flat route was larger, probably due to higher physical effort cycling uphill without electrical support. Therefore, the findings may suggest that conventional bicycles are more sensitive to individual- and environmental factors, such as topography. Compared to studies on conventional bicycles, Oja and colleagues [32] supported the present findings, in 68 commuting adults, as the relative intensity was 57–65% of \( \overset{.}{\mathrm{V}}{\mathrm{O}}_2 \max \), whereas Geus et al. [17] observed a higher intensity of 77–79% of \( \overset{.}{\mathrm{V}}{\mathrm{O}}_2 \max \).

Exercise intensity, presented as METs, was in the present study also lower when subjects cycled on the E-bike compared to the conventional bike, however, figures for the hilly and flat routes were similar. The explanation for similar average MET-values during the flat and hilly routes are the periods of downhill with lower energy demand following the periods of ascending during hilly biking. A few previous studies have presented MET-values (4–6 METs) for E-bikes when cycling on a varied terrain [19,20,21,22]. These findings were similar, or somewhat lower, to the estimated METs in the present study, however, considerable lower than the measured METs. Presenting energy expenditure or exercise intensity using the standard 1-MET value (3.5 ml O 2 /kg/min) may result in lower reported levels in individuals since the standard 1-MET value has been reported to be overestimating resting metabolic rate by 35 and 14% in individuals with a mean BMI of 30 and 20 kg/m2, [25], respectively, and similar to the present study (resting metabolic rate of 3.0 ml O 2 /kg/min). However, our results indicate that both using the standard 1-MET or measured RMR, e-biking can be categorised as at least MVPA.

E-biking was faster and less intense, making it suited for busy modern lives. It will get you quicker to work and you might not need a shower. But, on the other hand, less time spent cycling at a lower intensity is not ideal as most people are inactive. However, most of the time spent cycling on both the E-bike and the conventional bicycle, in both routes, was spent in MVPA.

The present findings indicate that due to lower intensity and trip duration, an E-bike needs to be used more frequently or to cover longer distances, to achieve the same health benefits [15], as adults commuting by a conventional bicycle. On the other hand, in several European nations, most adults do commute by motorised transportation to work [33], which according to Costa et al. [18] can be categorised as sedentary behaviour or light intensity physical activity (below 3 METs). Since the present findings indicate at least a moderate intensity of physical activity when e-biking, an increase in the level of transport-related physical activity will follow switching from car commuting to E-bikes, and more individuals probably meeting the physical activity recommendations. Also, considering that frequently reported barriers to cycling or walking for transport have been travel time [34,35,36,37] and physical effort [36, 37]; the E-bike seems to be a good option for those living too far away from work to walk or cycle with a conventional bike.

Strength and limitations

The main strengths of the present study were the objective measurements of RMR, direct measurements of \( \overset{.}{\mathrm{V}}{\mathrm{O}}_2 \max \) in the laboratory and \( \overset{.}{\mathrm{V}}{\mathrm{O}}_2 \) during the field tests as well as using GPS to measure elevation and distance covered. However, due to a small sample size not the findings are presented as descriptive rather than analytical. During the field tests, the participants may have cycled at a higher intensity, due to participating in an experimental study. In addition, the cycling trips is not necessarily representative to all cycling trips in Norway. The participants performed the four field tests on the same day, which may have affected our results. However, the route and type of bicycle were selected in random order.

Conclusion

Cycling on the E-bike resulted in lower trip duration and exercise intensity, compared with the regular bicycle. However, most of the time was spent in MVPA. Therefore, changing commuting mode from car to E-bike will significantly increase levels of physical activity while commuting.