Their heart rates also differed. In general, people’s heart rates were about 8 percent lower when they pedaled e-bikes, but still consistently hovered within the range considered moderate exercise. As a result, during the two weeks when the volunteers rode e-bikes, they accumulated sufficient minutes of moderate physical activity to meet the standard exercise recommendation of 150 minutes of moderate activity. When they rode the standard bikes, they did not.

Most also reported liking the pedal assist, Ms. Stenner says. More than two-thirds of the participants told the researchers they enjoyed the e-bikes and could imagine using them “for many years,” according to a final study questionnaire.

But whether e-bikes might pose a greater risk for injuries than standard bicycles remains an open question. “No serious injuries were reported to us,” during the research, Ms. Stenner says.

The other new study of e-bikes, which was published in December in Injury Prevention, is more cautionary, however. For it, researchers at New York University’s School of Medicine combed a national database of emergency room visits for information about accidents related to riding a standard bicycle, motorized scooter or an e-bike from 2000 to 2017.

They found plenty of reports. More than nine million men, women and children showed up in an emergency room after being hurt while riding a standard bike during those 17 years. Another 140,000 injured themselves on scooters, and about 3,000 on e-bikes (an uncommon novelty in the early years of the study). In general, the e-bike injuries were the most severe and likely to require hospitalization.

Why e-bikers tended to hurt themselves more seriously than other riders is not clear from the injury data, says Charles DiMaggio, an injury epidemiologist at NYU Langone Health, who led the new study. But speed likely played a role. “We know that e-bikes can go faster than traditional pedal cycles,” he says, unless you are a bike racer who bombs down hills at more than 20 or 30 miles per hour. “And we know that increased speed often results in more-severe injuries.”

But there is encouraging news embedded within the injury statistics, he says. In the earliest years covered by the study, a majority of e-bike injuries involved children under age 18, who seem to have been the earliest adopters of this new cycling technology. The incidence among this group declined precipitously in the later years of the study, though, even as it rose among people aged 45 to 65. This shift could indicate that the younger riders became “more familiar” with how to ride e-bikes safely, Dr. DiMaggio says, a development that, with time and experience, should reduce injuries among other, older riders. Or the numbers could suggest that fewer young people are using e-bikes, leaving their parents or grandparents to be the ones now to try out e-bikes, and fall off them.