Verbal instructions play a key role in motor learning and performance. Whereas directing one's attention toward bodily movements or muscles (internal focus) tends to hinder performance, instructing persons to focus on the movement outcome, or an external object related to the performed task (external focus) enhances performance. The study's purpose was to examine whether focus of attention affects maximal force production during an isometric midthigh pull (IMTP) among 18 trained athletes (8F & 10M). Athletes performed 3 IMTP trials a day for 3 consecutive days. The first day was a familiarization session in which athlete's received only control instructions. The following 2 days athletes received either control, internal, or external focus of attention instructions in a randomized, within-subject design. Compared to performance with an internal focus of attention, athletes applied 9% greater force when using an external focus of attention (p < 0.001, effect size [ES] = 0.33) and 5% greater force with control instructions (p = 0.001, ES = 0.28). A small positive 3% advantage was observed between performances with an external focus of attention compared with control instructions (p = 0.03, ES = 0.13). Focusing internally on body parts and/or muscle groups during a movement task that requires maximal force hinders performance, whereas focusing on an object external to the self leads to enhanced force production, even when using a simple multijoint static task such as the IMTP.
http://www.canberra.edu.au/researchrepository/items/04454bad-cbdb-461a-bf25-6784c5fd65cd/1/ Copyright: ©2016 National Strength & Conditioning Association Version:This is the non-final version of an article that was accepted for publication in the Journal of Strength and Conditioning Research, which has been published at http://doi.org/10.1519/JSC.0000000000001188 . Changes resulting from the publishing process may not be reflected in this document. ABSTRACTThis study determined whether body composition, strength and power changes that occur during pre-season can be maintained during an international rugby sevens season. Fourteen male international rugby sevens players (age 21.4 ± 2.2 y; mean ± SD) were categorized as a forward (n=7) or back (n=7), and assessed for height, mass (M), skinfolds (S) (∑7), upper body (UB) strength, lower body (LB) strength and LB power. Bench press, back squat and a countermovement jump were used to measure strength and power at three time points: initial, early season and late season. Forwards were taller (185 ± 4cm), heavier (95 ± 6kg) and possessed a greater lean body mass (55.5 ± 4.0 M·S -0.14 ) than backs (181 ± 8cm, 88.5 ± 5.5kg, 51.9 ± 3.4 M S -0.14 ). Over the full season, small (~5% ± 5%; mean ± 90% confidence limits) positive changes occurred in body composition. LB strength gained during the pre-season decayed in-season, whereas UB strength increased moderately (~10% ± 3%) across the season. Power showed inconsistencies between measured variables with a moderate positive change across the season in mean velocity and relative peak power. Forwards showed a small decrease in peak power (relative and absolute). Moderate changes were observed in mean power over the season, forwards decreasing (~6% ± 6%) and backs increasing (~8% ± 6%). Rugby sevens forwards in this study found it difficult to maintain and improve power qualities in-season.Training loads of forwards and backs should be differentiated to maximize strength and power inseason. KEY WORDSPre-season, in-season, back squat, bench press, countermovement jump
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The purpose of this investigation was to identify differences in end range of motion (ROM) kinetic and kinematic strategies between highly resistance and vertical jump-trained athletes and controls. Weightlifters (WL: n = 4), short track speed skaters (STSS: n = 5), and nonresistance-trained controls (C: n = 6) performed 6 standing vertical squat jumps (SJ) and countermovement jumps (CMJ) without external resistance. Jump testing was performed using 3-dimensional marker trajectories captured with a 15-camera motion analysis system synchronized with 2 in-ground force plates. During SJ, there were large effects for the difference in time before toe off of peak vertical velocity between WL to STSS and C (ES: -1.43; ES: -1.73, respectively) and for the decrease between peak and toe off vertical velocity (ES: -1.28; ES: -1.71, respectively). During CMJ, there were large effects for the difference in time before toe off of peak vertical velocity between WL to STSS and C (ES: -1.28; ES: -1.53, respectively) and for decrease between peak and toe off vertical velocity (ES: -1.03; ES: -1.59, respectively). Accompanying these differences for both jump types were large effects for time of joint deceleration before toe off for all lower body joints between WL compared with C with large effects between WL and STSS at the hip and between STSS and C at the ankle. These findings suggest that the end ROM kinetic and kinematic strategy used during jumping is group-specific in power-trained athletes, with WL exhibiting superior strategies as compared with resistance- and jump-trained STSS.
Williams, KJ, Chapman, DW, Phillips, EJ, and Ball, N. Load-power relationship during a countermovement jump: A joint level analysis. J Strength Cond Res 32(4): 955-961, 2018-This study aimed to investigate whether hip, knee, and ankle peak power is influenced by the relative load lifted, altering the joint and system load-power relationship during a countermovement jump (CMJ). Twenty-three male national representative athletes (age: 20.3 ± 3.1 years, squat 1 repetition maximum [1RM]: 133.8 ± 24.8 kg) completed 3 CMJs at relative barbell loads of 0, 10, 20, 30, and 40% of an athlete's estimated back squat 1RM. Ground reaction force and joint kinematics were captured using a 16 camera motion capture array integrated with 2 in-ground triaxial force plates. Hip ((Equation is included in full-text article.)= 20%, range 0 > 40%), knee ((Equation is included in full-text article.)= 0%, 0 > 20%), and ankle ((Equation is included in full-text article.)= 40%, 0 > 40%) peak power was maximized at different percentages of absolute strength, with an athlete-dependent variation in load-power profiles observed across all lower-body joints. A decrease in system (body + barbell mass) peak power was significantly (p ≤ 0.05, r = 0.45) correlated with a reduction in knee peak power. Timing of instantaneous system and hip peak power occurred significantly closer to toe-off as load increased. The findings highlight that the generation and translation of lower-body joint power is influenced by external load and athlete-dependent traits. This subsequently alters the load-power profile at a system level, explaining the broad spectrums of loads reported to optimize system power during a CMJ. When training, we recommend that a combination of barbell loads based on assorted percentages of the estimated 1RM be prescribed to optimize joint and system power during a CMJ.
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