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Background: This study aimed to explore muscle strength production and its underlying neuromuscular characteristics in sedentary and trained individuals with intellectual disability (ID) compared with healthy sedentary individuals., Methods: Three adult groups (age: 25.07 ± 0.70) consisting of sedentary individuals with ID (IDSG), trained individuals with ID (IDTG) and a control group (CONT) participated in the present study. Peak torque (PT) during maximal voluntary isometric contraction, voluntary activation level (VAL), surface electromyography (sEMG) recordings, electrophysiological (M max ) and potentiated twitch torque (PTT responses) of the knee extensor muscles and thigh muscle volume were assessed., Results: Compared with CONT and IDTG, respectively, IDSG presented significantly lower PT (-48% and -42%), VAL (-24% and -9%), sEMG (-49% and -29%), M max (-41% and -39%) and PTT (-32% and -28%) values. These deficits were reduced between IDTG compared with CONT (i.e. PT: -10%; VAL: -16%; and sEMG: -28%) or did not differ anymore (PTT and M max ). Normalising PT to thigh muscle volume and/or computing theoretical PT value overwhelm strength production differences between IDTG and CONT. Training background influences the outcomes with IDTG exhibiting greater PT, VAL, sEMG, M max and PTT than IDSG., Conclusions: Strength production deficit in IDSG was related to both muscular and neural characteristics compared with healthy controls whereas this deficit mainly arises from neural characteristics for IDTG., (© 2019 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.)

The interest in whole-body vibration (WBV) for the enhancement of neuromuscular performance has received considerable attention. However, scientific evidence supporting the optimal prescription of WBV settings is lacking. This study investigated the acute effect of WBV combining high frequency/high peak-to-peak displacement (HH) or low frequency/low peak-to-peak displacement (LL) vs. sham intervention (SHAM) on lower limb muscle power and stiffness. A total of 223 volunteers were randomly assigned to either the HH, LL or SHAM group. Countermovement jump (CMJ) height, maximal and average power, maximal and average lower limbs stiffness obtained during a hopping test were recorded before and after the respective intervention. After the intervention, the HH group showed an increase of 4.64% in CMJ height (p<0.001) whereas the values of both the LL and SHAM groups did not change. In addition, maximal and average power of the lower limbs were significantly increased in all groups (p<0.001; 10.89% and 12.82%, respectively) while no effect on lower limbs stiffness was observed. Our data show that high frequency combined with high peak-to-peak displacement is the most optimal WBV setting for CMJ height enhancement. Further investigation should be undertaken to ascertain the effectiveness of WBV on lower limbs stiffness., (© Georg Thieme Verlag KG Stuttgart · New York.)

Whether a whole body vibration session can enhance muscle voluntary activation remains debated. This pilot study thus investigated the acute effects of an intervention with whole body vibration versus a "sham" intervention on the voluntary activation of knee extensor muscles. Ten healthy subjects volunteered to participate in two interventions, vibration and sham, in randomized order. Knee extensor muscle voluntary activation, contractile properties and maximal voluntary isometric contraction were assessed before and immediately after each intervention. No significant differences were found for any of the variables. After both interventions, muscle activation remained unchanged, whereas maximal voluntary isometric contraction was significantly reduced (p<0.05). In conclusion, the two interventions induced the same adaptations in the knee extensors. These findings can be useful in conceiving whole body vibration protocols, although future research is warranted to address the influence of vibration on neural adaptation. [ABSTRACT FROM AUTHOR]