Adding just 100 grams to a running shoe increases the metabolic cost of running by 1%.

A landmark 2016 study by researchers at the University of Colorado Boulder confirmed that shoe mass significantly affects running economy. Led by researcher Wouter Hoogkamer, the team tested runners on a treadmill using identical-looking shoes that varied in weight by 100 grams. The results demonstrated that for every 100 grams added per shoe, the aerobic demand of running increased by approximately 1%.This metabolic penalty arises because running involves a continuous cycle of accelerating and decelerating the limbs. Unlike weight carried on the torso, weight on the feet demands more energy because it sits at the end of a long lever—the leg. This is known as the "pendulum effect," where adding mass farther from the pivot point (the hip) increases the muscular effort required to swing the limb.For an elite marathoner running at a 2:03:00 pace, a 1% increase in metabolic cost can translate to a performance loss of approximately 30 to 60 seconds. This explains why manufacturers like Nike and Adidas invest heavily in PEBA-based foams such as ZoomX, which deliver high energy return while remaining remarkably lightweight. By reducing shoe mass from 250 grams to 150 grams, an athlete can theoretically improve their running efficiency enough to break personal records without any change in fitness level.