EMTBs may not be for the lazy after all, a study from the Brigham Young University published in the Journal of Medical Internet Research (yes that's a real thing) suggests.
The study showed that despite riders on eMTBs believing they got significantly less of a workout on bikes with motors, their average heart rates were at 94% of those who used conventional bikes.
The limited study recruited 33 mountain bikers aged 18-65, with a median age of 37.8 years. There had varying degrees of experience, from less than one year of cycling to over 11. The participants completed two laps of a 5.5 mile circuit with 700 metres of elevation gain - one lap was on a Class 1 pedal-assist 2017 Specialized Turbo Levo FSR Comp Carbon 6Fattie models with a maximum assistance speed of 20 mph (32 kph), and the other on the 2017 Specialized Stumpjumper FSR Comp 6Fattie model. The idea was to have two bikes that were as similar as possible except for the motor. Apple watches and Polar H10 heart rate monitors were used to monitor heart rates, and Strava was used to record ride speed, distance, and time.
Riders completed the loop on average 12 minutes 40 seconds faster on the eMTBs but their average heart rates were roughly similar over the loop - 154.8 bpm on the regular bike and 144.9 bpm on the eMTB. This placed the participants in the same 'vigorous intensity' exercise zone on both bikes. Despite these similarities, when asked about the experience afterwards, most of the riders agreed with the statement, "heart rate is considerably lower while riding an eMTB as compared with a conventional mountain bike."
In short, the study is suggesting that eMTBs offer a good form of workout without the rider feeling like they are exercising as much. It goes on to suggest they may be a benefit for "more sedentary individuals" to use eMTBs "to engage in regular physical activity and meet physical activity guidelines."
The new study also supports previous research by much of the same team, which includes students Taylor Hoj and Clark Julian, that found e-bikes (not e-mountain bikes) are capable of providing much of the cardiovascular health benefits that conventional bikes provide.
"Those who used e-bikes still had elevated heart rates and enjoyed their experience," said Dr. Ben Crookston, one of the study's authors and a professor in BYU's College of Life Sciences. "I think this is a game changer for those who have found biking too difficult. It makes this important form of exercise accessible to a broader community. We are at least encouraged from a health promotion standpoint that we now have another tool to promote an active lifestyle.”
Of course, we should take these results with a heaping tablespoon of salt. This study used a small sample size so we should be careful to not extrapolate these results too far. Furthermore, the participants were not regular eMTB riders so may have been exerting themselves more than a long-time eMTB rider who is more used to the equipment. Additionally heart rate is only one measurement of exertion, the study itself suggests that "more sophisticated measures, such as maximal oxygen uptake, metabolic equivalents, and watts" would provide a stronger conclusion.
The full study can be read here