Effects of flexibility combined with plyometric exercises vs isolated plyometric or flexibility mode in adolescent male hurdlers.

BACKGROUND: This study aims to determine the effect of flexibility exercises combined with plyometrics in hurdles race, on physical fitness, motor skills (MS) and hip range of motion. METHODS: Thirty-four male hurdlers, (age=15.7±0.7 years, body mass=59.7±2.3 kg, height=170.8±2.4 cm) were randomly assigned to four independent groups. The (Gflex+plyo), the (Gplyo), the (Gflex) and a control group (Gcon). All participants performed different tests: a test of right and left hip flexion (RHF, LHF) and extension (RHE, LHE), squat jump (SJ), countermovement jump (CMJ), stiffness jump (STFJ) and three (MS) exercises (running, hopping and leaping). A 60-m sprint on the hurdles was also performed. RESULTS: The two-way analyses of covariance for repeated measures showed that Gflex+plyo increased significantly: the CMJ, performance on 60-m and showed higher performance in the between groups' comparison. The Gflex+plyo and Gflex showed the higher percentages of changes in flexibility (RHF: 3.2±1.3% and 3.0±2.1%; RHE: 6.4±2.4% and 9.4±4.1%, LHE: 8.4±3.4% and 7.8±4.3%, respectively). Gplyo increased significantly the LHF (3.9±1.4%) more than the other groups. In the between groups' comparison, Gplyo showed the higher percentage of change in STFJ (6.4±1.8%) and the Gflex+plyo showed the higher values in running and hopping (10.7±4.6% and 13.3±2.1%, respectively). CONCLUSIONS: Specific stretching exercises combined with plyometrics may be more beneficial than other training strategies in young sprint-hurdlers. This may better improve physical fitness, hip range of motion and may increase different level of skills which may better improve performance in hurdles race.

Auditory cues behind congenitally blind subjects improve their balance control in bipedal upright posture.

BACKGROUND: Congenitally blind subjects developed postural adaptations improving somatosensory and vestibular systems to maintain upright stability and auditory skills to orient them in environment. However, the influence of auditory cues on upright stability in congenitally blind subjects stays unknown. RESEARCH QUESTION: The aim of this study is to define the influence of an auditory cue in congenitally blind subjects back space on their balance posture. METHODS: Eleven sighted subjects and eleven congenitally blind subjects performed upright bipedal and unipedal quiet stances on a force plate with two conditions of auditory cue played by a loudspeaker placed 2 m behind them. Mean CoP velocity were recorded. Student test was used to compare significant difference between blind and sighted subjects bipedal and unipedal postures stability in both conditions of auditory cue. RESULTS AND SIGNIFICANCE: Results showed that congenitally blind subjects had no significant difference in mean sway velocity compared to sighted subjects in bipedal upright posture in auditory signal condition. However, blind subjects had significant lower mean sway velocity than sighted subjects in bipedal upright posture without sound. Blind subjects had significant increased mean sway velocity during unipedal quiet standing in both auditory cue conditions (with and without sound). The results showed that congenitally blind subjects used auditory cues placed behind them in order to improve their balance control in bipedal upright posture. In this case, blind subjects could better use compensatory mechanisms to perform quiet standing as sighted subjects. Without sound or in unipedal upright posture, congenitally blind subjects probably have sensory perturbations or limitations that impose them adaptations in order to avoid falling risk. Auditory cues should be study in the aim to better understand the compensatory mechanisms used by congenitally blind subjects to perform postural balance in usual environment.