Eliminating high-intensity activity during growth reduces mechanical power capacity but not submaximal metabolic cost...

Decreases in activity levels in children worldwide are feared to have long-term health repercussions. Yet, because of the difficulty of performing controlled long-term studies in humans, we do not yet understand how decreases in childhood activity influence adult functional capacity. Here, in an avian bipedal model, we evaluated the elimination of all high-intensity activity during growth on adult performance. We evaluated three alternative hypotheses: Elimination of high-intensity activity 1) does not influence adult function, 2) results in task-specific deficits in adulthood, or 3) results in deficits that generalize across locomotor tasks. We found that animals restricted from jumping and sprinting during growth showed detriments as adults in maximal jump performance in comparison to controls, but did not require more metabolic energy during steady-state running or standing. From this, we conclude that functional deficits from elimination of high-intensity exercise are task specific and do not generalize across all locomotor functions.NEW & NOTEWORTHY Decreasing childhood activity levels are feared to have long-term health repercussions, but testing this hypothesis is hampered by restrictions of human experimentation. Here, in a bipedal animal model, we examine how the elimination of high-intensity activity during all of maturation influences adult locomotor capacity. We found restricted activity during growth reduced mechanical power capacity but not submaximal metabolic cost. This suggests that reduced childhood activity may result in task-specific, rather than generalized locomotor deficits.