European Journal of Physical Education and Sport Science ISSN: 2501 - 1235 ISSN-L: 2501 - 1235 Available on-line at: www.oapub.org/edu Volume 3 │ Issue 9 │ 2017 doi: 10.5281/zenodo.847756 CONTINUOUS WEIGHTED JUMPING: EFFECTS ON VERTICAL JUMP HEIGHT Sevene T. G.1, DeBeliso M.2, Carson C.3, Berning J. M.3, Harris C.4, Adams K. J.1i California State University, Monterey Bay, Seaside, CA, USA 1 2 Southern Utah University, Cedar City, UT, USA New Mexico State University, Las Cruces, NM, USA 3 Metropolitan State University of Denver, Denver, CO, USA 4 Abstract: High intensity, near maximal exercise is a conditioning activity which can cause neural hyper-stimulation and lead to acute enhanced power production known as postactivation potentiation (PAP). Investigations need to be conducted to better understand the duration and intensity of the conditioning activity and subsequent effects on the fatigue-potentiation relationship. Purpose: To investigate the effect of 30 seconds of continuous vertical jumping while wearing a vest loaded with 30% of body weight on power output as measured with a maximal vertical jump (VJ). Methods: 14 volunteers (8 weight trained males [23.0+2.9 yrs, 79.8+13.8 kg, 179.9+8.6 cm] and 6 weight trained females [23.0+2.9 yrs, 69.9+13.3 kg, 171.6+7.0 cm]) participated in the study. Pre-testing consisted of each participant performing 3 VJs. The highest VJ was recorded as baseline. A weighted vest was then loaded equaling 30% of the individual's body weight; while wearing the weighted vest, participants performed 30 seconds of continuous VJs. Immediately after jumping participants were seated in a chair for 3 minutes; at 3 minutes, they performed a maximal VJ without the weighted vest in the same manner as done during pre-testing. Two additional VJs were repeated at 4 and 5 minutes post weighted jumping. A mixed design ANOVA with repeated measures was performed. Results: Results showed main effects for each of the independent variables tested, gender and jump. The posttest values at all 3 intervals for both males and females were significantly different from the pretest scores (F [3, 36] = 21.74, p < 0.05). Post hoc analysis indicated that the pretest VJ scores (M = 280.1±18.6 cm) decreased significantly Corresponding Author: Dr. Kent Adams, 100 Campus Center, Kinesiology Department, Valley Hall, Suite D, CSU Monterey Bay, Seaside, CA 93955, 831-582-4114, 831-582-3737 (fax), kadams@csumb.edu i Copyright © The Author(s). All Rights Reserved. © 2015 – 2017 Open Access Publishing Group 12 Sevene T. G., DeBeliso M., Carson C., Berning J. M., Harris C., Adams K. J. CONTINUOUS WEIGHTED JUMPING: EFFECTS ON VERTICAL JUMP HEIGHT at the 3 minute interval (M = 278.1±18.3 cm), followed by a significant increase in height at the 4 minute interval (M = 281.1±18.7 cm), and another increase at the 5 minute interval (M = 283.0±19.2 cm). Males jumped significantly higher than the females across all trials (p<0.05), however there was no significant difference between male and female VJ gain scores between pre-PAP VJ and 3, 4 and 5 minute post weighted exercise VJ. Conclusion: Results suggest that 30 seconds of weighted VJs causes fatigue which decreases VJ at 3 minutes post exercise. However, a PAP effect was seen at 4 and 5 minutes post weighted exercise significantly increasing VJ above pre testing. From a practical perspective, coaches must be aware of the complex nature of the fatiguepotentiation relationship when attempting to elicit a PAP effect in the individual athlete. Keywords: post-activation potentiation; power; jump 1. Introduction Post-Activation Potentiation (PAP) is a neuromuscular phenomenon which occurs when the nervous system is acutely hyper-stimulated and allowed to recover, resulting in increased muscular power output (5, 7, 12, 14, 17, 20, 22, 25, 30). Various types of conditioning activities (e.g., weighted jumps; functional isometrics; heavy lifting) have been used to hyper-stimulate the nervous system prior to performing an explosive movement (e.g., vertical jump, shot put, sprinting) (1, 3, 4, 10, 11, 16, 18, 21, 29, 31-33). Key to eliciting a PAP response is the fatigue-potentiation relationship (13, 19, 24, 26, 27, 30). Basically, this can be thought of as a balancing act; that is, with a stimulus or conditioning activity fatigue occurs inhibiting potentiation; as one recovers, fatigue is reduced and in theory potentiation takes over; if a potentiation state occurs, research suggests there is an optimal time window of potentiation which may elicit a PAP response in an acute exhibition of power (8, 12-14, 19, 22, 24, 26, 27, 30). The length of this time window of potentiation has been the subject of several recent investigations (e.g., 1, 8, 13, 19, 26, 27), whereas the duration of the conditioning activity has experienced less research focus (e.g., 6, 12, 14, 22). Studies indicate that a conditioning activity that is too long in duration (e.g., > 5 total repetitions or 5 seconds of total contraction time) causes too much fatigue and limits the PAP effect (12, 14, 22). For downloading the full article, please access the following link: https://oapub.org/edu/index.php/ejep/article/view/982 European Journal of Physical Education and Sport Science - Volume 3 │ Issue 9 │ 2017 13