A biomechanical comparison of self-selected and experimentally controlled speeds and grip widths during the bench press exercise.

The purpose of this study was to compare one repetition maximum (1RM), a rating of discomfort, and myoelectric activity between self-selected and experimentally controlled speeds and grip widths during the bench press (BP). Four BP conditions used were self-selected speed and grip (SS), self-selected speed and experimentally controlled grip (SC), experimentally controlled speed and self-selected grip (CS), and experimentally controlled speed and grip (CC). Twenty male individuals completed 1RM measurements with each BP condition and then performed 16 BP trials (four trials per condition) for measuring myoelectric activity. A one-way repeated measures analysis of variance was conducted for 1RM. Frequency analyses were conducted for a rating of discomfort. Two-way repeated measures multivariate analyses of variance were performed for myoelectric activity. SS showed a significantly higher 1RM than SC, CS, and CC. CC was characterised as the most uncomfortable BP condition (80%) followed by CS (15%), SC (5%), and SS (0%). There were no significant main effects and interaction of speed and width on myoelectric activity. A self-selected speed and grip width was recommended because it would allow a more practical and ecologically valid assessment of 1RM and a lower rating of discomfort during the BP.

Predicting individual differences in motor learning: A critical review.

The ability to predict individual differences in motor learning has significant implications from both theoretical and applied perspectives. However, there is high variability in the methodological and analytical strategies employed as evidence for such predictions. Here, we critically examine the evidence for predictions of individual differences in motor learning by reviewing the literature from a 20-year period (2000-2020). Specifically, we examined four factors: (i) the predictor and predicted variables used, (ii) the strength of the prediction and associated sample size, (iii) the timescale over which the prediction was made, and (iv) the type of motor task used. Overall, the results highlight several issues that raise concerns about the quality of the evidence for such predictions. First, there was a large variation in both predictor and predicted variables, suggesting the presence of a large number of researcher degrees of freedom. Second, sample sizes tended to be small, and the strength of the correlation showed an inverse relation with sample size. Third, the timescale of most predictions was very short, mostly constrained to a single day. Last, most studies were largely restricted to two experimental paradigms - adaptation and sequence learning. Based on these issues, we highlight recommendations for future studies to improve the quality of evidence for predicting individual differences in motor learning.

Lower Limb Force Asymmetries During Landing and Jumping Exercises: A Pilot Study.

Significant asymmetries can exist between the lower limbs' force production during the take-off phase of bilateral jumping exercises. Some studies have indicated that similar asymmetries can also exist during the landing phase. It has not been demonstrated if the magnitude of lower body asymmetry was similar between the landing (L) and take-off (TO) phases of bilateral jumping movements. The main purpose of this study was to compare the asymmetry measured during the L and TO phases of bilateral jumping exercises to determine if there was a difference in asymmetry between the phases. In order to quantify the degree of the asymmetry, the vertical ground reaction force (vGRF) produced by each leg was measured during execution of vertical-jump (VJ) and drop-jump (DJ) exercises. Eleven recreationally trained individuals completed three VJ and DJ trials while two force plates recorded vGRF. A two-way repeated measures ANOVA was used to compare the asymmetry levels with the phase (within- subject: L and TO) and the exercise (within- subject: VJ and DJ) being factors. A significant difference in the asymmetry was found between the L and TO phases (p < .05). These findings suggested that there was greater asymmetry in the distribution of vGRF during landing than during take-off.