Yes, regular training can decrease your caloric expenditure. Just how many fewer calories you’ll burn when you’re well trained is highly individual, says Bryan Heiderscheit, professor of orthopedics and rehabilitation and director of the runners clinic at the University of Wisconsin-Madison. However, the difference in calorie burn between your well-trained and less-trained self is not enough to warrant a crosstraining obsession.
“For the amount of calories that you might not spend as you become more experienced and refined, it’s not really worth thinking about” crosstraining, Heiderscheit says. Proof: One study published in the Journal of Applied Physiology determined that well-trained runners burn five to seven percent fewer calories than their nonathletic counterparts. A run you did as a newbie athlete that burned 500 calories, for example, might burn 465 to 475 calories when you’re better trained, assuming you’ve stayed the same weight.
That drop in calories spent signifies an increase in economy, the goal of most endurance runners because the miles get easier when the body’s not working as hard to fuel them.
But if your main goal is to burn the most calories possible on each run, up your training speed; several studies have shown that runners are most efficient at frequently used training paces, and that the faster you run, the more calories you’ll burn per mile. So quickening your clip may be the only tweak necessary to maintain the burn. Check out this Runner’s World calculator to see how a change in pace will affect your caloric expenditure. According to the calculator, if a 150-pound runner ran 12-minute pace for an hour, he’d burn 567 calories. Drop that pace to 11-minutes per mile, and he’d burn 618 calories an hour.
THE BOTTOM LINE: It’s likely you’ll burn slightly fewer calories the better trained you are. If you train at a constant pace, increasing it should help your well-trained self maintain the calorie burn of your newbie running days.