The Effects of Different Wearable Resistance Loads and Placements During Vertical Jumping and Sprint Running
Several training options are available to produce specific adaptations depending on the requirement of the sport and the athlete. Specific strength exercises that closely mimic the sporting performance action enable overload and most likely optimise transference of adaptation to the sport/activity of interest. An example of this is wearable resistance (WR) (i.e. an external load attached to the body) which enables movement specific actions to be performed with additional resistance attached to various areas of the body. WR may be a potential training option that allows athletes to train full body strength, speed and power exercises without compromising technique. Acute and longitudinal performance increases have been reported in jumping and sprint running with WR; however, clarity is lacking when specifying the optimum load and load placement position. Previous WR research has involved weighted vests, hand held weights or loads attached to the thigh, ankle or foot. However, recent technological developments have enabled WR loading configurations to be attached to multiple areas of the body allowing greater functional dynamic actions to be performed. Therefore, the purpose of this thesis was to determine the acute kinematic and kinetic changes in vertical jump (VJ) and sprint running performance with differing load magnitudes and load placements. The aim of the first study was to determine the acute changes in kinematics and kinetics when an additional load equivalent to 3 or 6% body mass (BM) was attached to the upper or lower body during vertical jumping. Twenty athletic subjects performed the counter movement jump (CMJ), drop jump (DJ) and pogo jump (PJ) in a randomised fashion wearing no external load, 3 or 6% BM affixed to the upper or lower body (three jumps per condition). The main finding in terms of the landing phase was that the effect of WR was non-significant. However, landing relative vertical ground reaction force (Fv) tended to be higher with the same magnitude of lower WR compared to upper WR. With regards to the propulsive phase the main findings were that: 1) for both the CMJ and DJ, WR resulted in a significant decrease in jump height (CMJ: -12 to -17%, DJ: -10 to -14%), relative peak power (CMJ: -8 to -17%, DJ: -7 to -10%) and peak velocity (CMJ: -4 to -7%, DJ: -3 to -8%); 2) there was no significant effect of load placement; and, 3) PJ reactive strength index was significantly reduced (-15 to -21%) with all WR conditions. Consideration should be given to the inclusion of WR in sports where VJ?s are important components as it may provide a novel training stimulus. The purpose of the second study was to determine the acute changes in kinematics and kinetics when an additional load equivalent to 3% BM was attached to the anterior or posterior surface of the lower limbs during sprint running. Nineteen male rugby athletes performed six 20 m sprints in a randomised fashion wearing no resistance or 3% BM affixed to the anterior or posterior surface of the lower limbs (two sprints per condition). No significant differences were found between the anterior and posterior WR conditions in any of the variables of interest. There was no significant change in sprint times over the initial 10 m; however the 10 to 20 m split times were significantly slower (-2 to -3%) for the WR conditions compared to the unloaded sprints. A significant change in the relative force-velocity (F-v) slope (-10 to -11%) and theoretical maximum velocity (V0) (-5 to -6%) was found, while a non-significant increase in theoretical maximum force (F0) (5%) occurred. WR of 3% BM may be a suitable training modality to enhance sprint running acceleration performance without negatively affecting sprint running kinematics, particularly for athletes requiring a more force dominant F-v profile. WR provides a novel overload training method for an athlete that enables vertical jumping and sprint running to be performed without negatively impacting on kinematics. WR training may benefit athletes for whom explosive lower-body movements such as jumping and sprint running are performed as part of training and competition.