By GRETCHEN REYNOLDS
August 24, 2017
Parenting tends to bring with it an increase in joy and a decline in fitness. Epidemiological studies indicate that parents exercise less when they have young children, thanks to the scheduling demands of child care. Jogging strollers are a popular way for new parents to integrate their children directly into their exercise time and capitalize on the additional exertion of pushing that extra weight. But according to one of the first in-depth scientific examinations of the biomechanics and caloric expenditure involved in jogging with strollers, how you run behind a stroller may determine how much physical benefit you actually experience.
For the new study, published in PLOS One, researchers at Seattle Pacific University began by watching stroller-runners and cataloging the ways in which they controlled the carriage. The scientists determined that most runners used one of three techniques: They held the stroller’s handlebar with one hand, or two hands, or pushed and chased the carriage in repeated spurts.
The researchers then gathered at a local track 16 fit male and female runners with no experience using a jogging stroller. After outfitting them with special breath and cardiac monitors, the scientists asked each participant to run for 800 meters at a pace that felt comfortable. Next, they handed each a stroller containing a 35-pound dummy and had them complete three more runs, deploying alternately the one-handed, two-handed and push-and-chase techniques, while urging the runners to maintain the same pace and form as in their unencumbered run.
None of the runners were able to maintain their initial pace. Instead, their strides became shorter and choppier, particularly when they used one hand to hold the stroller or when they pushed and chased it. And, because they had slowed so much, their heart rates and energy costs did not rise compared with a normal jog, even though they were now pushing additional weight. Their form and pace were closest to normal when they used two hands.
The lesson? If parents wish to obtain ‘‘the most possible bang’’ from their exercise time, they should push themselves while they push the stroller, says Ryan Alcantara, who led the study as an undergraduate at Seattle Pacific.
Runners will burn significantly more calories in the same time frame if they maintain the same pace with a stroller that they once achieved without: According to Alcantara’s model, pushing a stroller at a constant speed increases the energy costs of running by 5 to 8 percent. The same 30-minute jog that would have burned about 360 calories for a 150-pound man or woman without a stroller should incinerate closer to 380 now, an amount that is small in terms of each run but cumulatively could contribute to weight control and improved fitness, Alcantara says.
Running at or near your prestroller pace ‘‘will feel much harder than before,’’ he adds. But as with parenthood, you get more out of it when you put more in.