title: External loading and maximum dynamic output in vertical jumping: the role of training history.
abstract: We examined the effect of training history on the load-power relationship in vertical jumping (VJ) by employing external loads ranging from -30% to +30% body weight (BW). Based on previous findings, we hypothesized that (1) the maximum dynamic output (power production and momentum generation) would be within the tested loading interval, and (2) the load-power and load-momentum relations would depend on the subject's training history. Thirty-one healthy male subjects of different training history (i.e., 9 strength-trained athletes, 12 speed-trained athletes, and 10 sedentary individuals), performed maximum countermovement jumps on a force plate while a pulley system was used to either reduce or increase the subject's BW. An increase in external loading during VJ resulted in a systematic decrease (p<.001) in power production and momentum generation in all 3 studied groups. We also observed significant Group×Load interactions (p<.01) for the load-power and the load-momentum relationships, probably due to the group differences in slopes of the trend lines that describe the loading-associated changes in power and momentum. The results suggest that, from the evolutionary standpoint, the human muscular system of the lower limbs could be designed to produce the maximum power output against the loads that are well below the mass and inertia of the human body.
authors.affiliation: Motor Control and Human Performance Laboratory, School of Kinesiology, University of Zagreb, Horvacanski zavoj 15, 10000 Zagreb, Croatia.
authors.forename: Sasa
authors.initials: S
authors.lastname: Vuk
authors.forename: Goran
authors.initials: G
authors.lastname: Markovic
authors.forename: Slobodan
authors.initials: S
authors.lastname: Jaric
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology; D001696:Biomechanical Phenomena / Q000502:physiology; D015992:Body Mass Index; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007719:Knee Joint / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D010806:Physical Education and Training; D055070:Resistance Training; D057185:Sedentary Behavior; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult