Visual control has an influence on postural stability. Whilst vestibular, somatosensoric and cerebellar changes have already been frequency analytically parameterized with posturography, sufficient data regarding the visual system are still missing. The aim of this study was to evaluate the influence of pathologic and simulated visual dysfunctions on the postural system by calculating the frequency analytic representation of the visual system throughout the frequency range F1 (0.03-0.1 Hz) of Fourier analysis. The study was divided into two parts. In the first part, visually handicapped subjects and subjects with normal vision were investigated with posturography regarding postural stability (stability effect, Fourier spectrum of postural sway, etc.) with open and closed eyes. The visually impaired and the normal group differed significantly in the frequency range F1 (p = 0.002). Significant differences of the postural stability between both groups were found only in the test position with open eyes (NO). The healthy group showed a significant loss of stability, whereas the impaired group showed an increased stability due to sufficient somatosensoric processes. Visually handicapped persons can compensate the visual information deficit through improved peripheral-vestibular and somatosensoric perception and cerebellar processing. In the second part, subjects with normal vision were examined under simulated visual conditions, e.g., hyperopia (3.0 D), reduced visual acuity (VA = 20/200), yoke prisms (4 cm/m) and pursuits (pendulum). Changes in postural parameters due to simulations have been compared to a standard situation (open eyes [NO], fixation distance 3 m). Visual simulations showed influence on frequency range F1. Compared to the standard situation, significant differences have been found in reduced visual acuity, pursuits and yoke prisms. A loss of stability was measured for simulated hyperopia, pendulum and yoke prisms base down. Stability regulation can be understood as a multi-sensoric process by the visual, vestibular, somatosensoric and cerebellar system. Reduced influence of a single subsystem is compensated by the other subsystems. Obviously the main part of reduced visual input is compensated by the vestibular system. Moreover, the body sway, represented by the stability indicator, increased in this situation.

It is important to be able to reliably reproduce active ROM and isometric strength evaluations. Using a standardized testing position, goniometry and HHD are reliable instruments in the assessment of shoulder and elbow joint performance testing. We showed good-to-excellent reproducible results for male and female control subjects and female handball athletes, although the single parameters in ROM and strength were different for each group and between the shoulders and elbows.

This study analyzed the effects of a resistance-type circuit training program (RCT) (30-35 minutes, performed twice a week for 10 weeks) on male handball players. Twenty-two males were divided into experimental (E; age 20.3 ± 0.5 years) and control groups (C; age 20.1± 0.5 years). Measures before and after RCT included squat (SJ) and countermovement jumps (CMJ), one repetition maximum (1-RM) ofbench press, pull-over and back half-squats, throwing velocity (a 3-step throw with run (RT), and a jump throw (JT)), repeated-sprint ability (six 2 x 15-m shuttle sprints with recording of best time for a single trial), anthropometric estimates of leg and thigh muscle volumes and mean thigh cross-sectional area (CSA), and a test of agility. The agility T-half test showed a significant interaction effect (p=0.001; η=0.422), with an inter-group difference in effect size (d) of 1.27 (dTG=1.24 vs. dCG=-0.03). The SJ displayed no interaction effect. The interaction effects for half back-squat (d=2.73, η=0.740) and CMJ (d=3.76, η=0.700) were large, but that for RT was smaller (η=0.460) than that for JT (η=0.745). The throwing velocity of C decreased for both measures, with negative effect sizes (d=-0.18 and d=-0.93 respectively). Upper body, leg, and thigh muscle volumes and thigh CSA increased significantly after resistance training. However, repeated-sprint parameters showed no significant changes. During the competitive season, 10 weeks of RCT with only 2 training sessions per week improved numerous measures of athletic performance in handball players, and such conditioning can be highly recommended as part of the annual training program for elite handball players.

The primary aim of the study was to examine the anthropometric characteristics, as well as the physical performance of professional handball players classified by playing position and competition level. Twenty male players (age: 20.4 ± 0.88 years) from the first handball league and 18 male players (age: 21.3 ± 1.61 years) from the second handball league were categorized as backs (8/8), pivots (5/4), and wings (7/6). The following variables were measured in both groups: peak power; vertical squat jump (SJ), and countermovement jump (CMJ); sprint times over 15 and 30 m; handball throwing velocity during the jump shot (JS); and 3 steps shot (T3 step); upper and lower limb muscle volumes; Yo-Yo Intermittent Recovery Test. Anthropometric data revealed significantly ( p = 0.003, = 0.248) less muscle volume for second league players (3.13 ± 0.29 l) than for first league (3.71 ± 0.82 l). The cross-sectional area for the first league players was also larger ( p = 0.010, = 0.192). Regarding performance parameters, we found significant ( p < 0.05 and > 0.20) league differences in five of 15 (33%) performance parameters: running throw ( = 0.285), SJ power ( = 0.670), SJ velocity ( = 0.900), peak upper limb power ( = 0.231) and Yo-Yo-IR 1 ( = 0.348). The second league players showed higher SJ velocity than the first league players ( = 0.900). In contrast, we detected a greater difference in SJ power ( = 0.670) but in favor of the first league players. Pivots were the players with the highest throwing velocity and wings were the fastest (15, 30 m sprint), strongest (countermovement jump), and most enduring (Yo-Yo-IR 1) athletes. Backs showed consistently the lowest level throwing velocity and sprint performance (exception: second league). The anthropometric differences between playing levels and playing positions may indicate the advantageous characteristics that the respective position demands, whereas the playing position differences in physical fitness characteristics may indicate training specificity issues that must be addressed cautiously.

No abstract

We have found that vision impairment influenced postural control, especially if acquired and not congenital. The somatosensory and vestibular systems serve as compensatory mechanisms, which is utilized most effectively by the congenitally blind.

Cataract surgery significantly improves postural stability. Considering the high cost of treating fall-related injuries in the elderly, the findings may imply that cataract surgery is cost effective in this regard.

Hermassi, S, Schwesig, R, Aloui, G, Shephard, RJ, and Chelly, MS. Effects of short-term in-season weightlifting training on the muscle strength, peak power, sprint performance, and ball-throwing velocity of male handball players. J Strength Cond Res 33(12): 3309–3321, 2019—This study analyzed the effects of in-season weightlifting training, conducted biweekly for 12 weeks. Twenty-two male handball players were divided into experimental (age: 20.3 ± 0.5 years, height: 1.85 ± 0.04 m, and body mass: 86.3 ± 9.4 kg) and control (age: 20.1 ± 0.5 years, height: 1.81 ± 0.05 m, and body mass: 83.9 ± 10.3 kg) groups, and performance was assessed before and after the intervention. Peak power was determined by a cycle ergometer force-velocity test, a vertical squat jump, and a countermovement jump. Measures of 1 repetition maximal strength included bench press, back half-squats, snatch, and clean and jerk. Handball-throwing velocity was assessed by standing, running, and jump throws. The change of direction T-half test and sprint times over 5, 15, and 30 m were recorded by paired photocells. The intraclass correlation coefficient of all parameters exceeded 0.75. Significant training effects were seen for all sprint (3/3) and throwing (3/3) measures, but only 7/14 strength parameters and 3/10 jump parameters. The largest increases of performance were for snatch (η2 = 0.627; d = 2.85) and 15-m sprinting (η2 = 0.852; d = 2.73). Countermovement jump force showed a negative response (d = −0.62). Three other parameters (V0 power for the upper and lower limbs, countermovement jump power) showed only small effect sizes (d = 0.45, d = 0.31, and d = 0.23, respectively). We conclude that 12 weeks of biweekly in-season weight training improved the peak power, maximal strength, sprinting, and throwing in handball players, but that their jump performance did not increase with this kind of intervention.