Stereotype Threat Effect on a Simple Motor Task: An Investigation of the Visuo-Spatial Working Memory.

Purpose: Based on the Chalabaev et al. (2013) study showing that in a Stereotype Threat (ST) situation the velocity of force production in a simple motor task can be affected, this study aimed to replicate this result and tested the role of Visuo-Spatial Working Memory (VSWM) in the ST effect. Method: Twenty one female athletes performed maximum voluntary contractions of the knee extensor muscles on an isokinetic dynamometer (Biodex), under neutral, ST, and ST with mental imagery conditions. The Rate Force of Development (RFD), a velocity indicator, was measured under each condition. VSWM and avoidance-related processes were measured in at a separate time. Results: Data confirmed that the RFD decreased when the stereotype threat was introduced, but also that mental imagery of the movement in the pre-contraction stage prevented this effect. Moreover, in the ST condition avoidance-related processes did not affect the RFD. In contrast, higher VSWM performance was associated with higher RFD. Conclusion: These findings suggest that the ST effects on a simple motor task can be explained by an alteration of working memory which impairs movement preparatory processes in the pre-contraction stage.

Does electrical stimulation enhance post-exercise performance recovery?

Elite sport requires high-volume and high-intensity training that inevitably induces neuromuscular fatigue detrimental for physical performance. Improving recovery processes is, therefore, fundamental and to this, a wide variety of recovery modalities could be proposed. Among them, neuromuscular electrical stimulation is largely adopted particularly by endurance-type and team sport athletes. This type of solicitation, when used with low stimulation frequencies, induces contractions of short duration and low intensity comparable to active recovery. This might be of interest to favour muscle blood flow and therefore metabolites washout to accelerate recovery kinetics during and after fatiguing exercises, training sessions or competition. However, although electrical stimulation is often used for recovery, limited evidence exists regarding its effects for an improvement of most physiological variables or reduced subjective rating of muscle soreness. Therefore, the main aim of this brief review is to present recent results from the literature to clarify the effectiveness of electrical stimulation as a recovery modality.

Effects of an electrostimulation training program on strength, jumping, and kicking capacities in soccer players.

The present study investigated the influence of a 5-week electrostimulation (EMS) training program on muscular strength, kicking velocity, sprint, and vertical jump performance in soccer players. Twenty amateur soccer players participated in the study, 10 in the electrostimulated group and the remaining 10 in a control group. Electrostimulation was applied on the quadriceps muscles over 5 weeks. Subjects were tested before, during (wk-3), and after (wk-5) the EMS training program. Maximal voluntary contraction using different contraction mode (i.e., eccentric, concentric, and isometric), vertical jump height, sprint running for 10 m, and ball speed were examined. We observed an increase in isometric and eccentric maximal knee extension torques and also a gain in ball speed performance without run up at wk-3. After 5 weeks of EMS training, eccentric, isometric, and concentric torques and ball speed had significantly improved. It appeared appropriate to conduct EMS training during at least 3 weeks to observe beneficial effects in specific soccer skills such as ball speed.