Interlimb Comparison of Electromyographic and Mechanomyographic Amplitude Responses of the Vastus Medialis to Submaximal and Maximal Isometric Contractions

Research on interlimb differences in neuromuscular recruitment patterns is limited. If interlimb differences exist, future exercise studies may have to reason for which limb (dominant vs. nondominant) to choose when examining muscle activation and contraction characteristics. PURPOSE: To investigate interlimb differences in normalized electromyographic (EMG) and mechanomyographic (MMG) amplitude responses of the vastus medialis muscle during submaximal and maximal isometric leg extension muscle actions. METHODS: Fourteen recreationally trained females (mean age ± SD = 22.3 ± 2.0 y) performed isometric leg extension muscle actions at 10-100% (10% increments) of maximal voluntary isometric contraction (MVIC) for their dominant (determined by kicking preference) and nondominant limbs. The muscle actions were performed unilaterally in the seated position of an isokinetic dynamometer. Subjects performed maximal isometric leg extension muscle actions for both limbs to determine each limb\u27s MVIC; then, they performed the submaximal isometric leg extension muscle actions in a random order of intensity. A bipolar surface EMG electrode arrangement and an accelerometer were placed over the vastus medialis muscle to detect EMG and MMG signals, respectively. The amplitudes of the EMG and MMG signals were expressed as root mean square (RMS) and normalized to their highest recorded value (% max). Two separate 2 (limb) × 10 (intensity) repeated measures ANOVAs were conducted to determine interlimb differences in normalized EMG and MMG RMS. RESULTS: There were no significant interactions for normalized EMG (p = 0.550) or MMG (p = 0.513) RMS. A main effect for limb was also not significant for normalized EMG (p = 0.653) or MMG (p = 0.490) RMS; however, a significant main effect for intensity was present for normalized EMG (10-90 \u3c 100, 10-80 \u3c 90, 10-60 \u3c 80, 10-50 \u3c 60 & 70, 20-30 \u3c 50, 20 \u3c 30 & 40% MVIC; p \u3c 0.001) and MMG (10-90 \u3c 100, 10-60 \u3c 90, 10-40 \u3c 70 & 80, 20 \u3c 60% MVIC; p \u3c 0.001) RMS. CONCLUSION: There were no interlimb differences in EMG or MMG RMS at submaximal and maximal isometric leg extension muscle actions. As they provided comparable information, either limb may be used for examining muscle activation and contraction characteristics in exercise studies using healthy, recreationally trained participants

The Effects of Eight Weeks of Leucine/Whey Protein Supplementation and Resistance Training on Isokinetic Peak Torque

Resistance training can lead to significant increases in muscle size and strength. Supplementing the diet with leucine and whey protein purportedly increases protein synthesis, potentially accelerating the processes involved with hypertrophy and strength increases. PURPOSE: To examine the effects of leucine and whey protein supplementation during 8 weeks of unilateral dynamic constant external resistance (DCER) training on isokinetic peak torque. METHODS: Thirty-five men (mean age ± SD = 22.3 ± 2.3 y) volunteered to participate in this investigation. Participants were randomly assigned to one of three groups: supplement (SUPP), placebo (PLA), or control (CON). The SUPP and PL participants then trained the leg extensors of the dominant limb (based on kicking preference) three times per week for eight weeks. Leg extension peak torque was determined for all participants pretraining and post training at 0, 60, 120, 180, 240, and 300°.s-1 using an isokinetic dynamometer. RESULTS: The results indicated there was no significant time × velocity × group interaction (p = 0.55). There was, however, a significant time × group interaction. Both the SUPP group (p \u3c 0.001) and the PLA group (p = 0.02) demonstrated significant increases in peak torque from pretraining to post training, while the CON group did not (p = 0.59). There was no difference in the magnitude of the gain in isokinetic peak torque between the SUPP and PLA groups (p = 0.62). CONCLUSION: Isokinetic peak torque increased significantly following 8 weeks of DCER training. However, the increase in peak torque was not augmented by leucine and whey protein supplementation

Digital Nucleic Acid Memory

Advancing digital Nucleic Acid Memory (dNAM) as an innovative data storage method, our research harnesses DNA\u27s high information density, stability, and energy efficiency for non-volatile memory applications . dNAM offers a sustainable alternative that improves upon the limitations of current memory materials

An evaluation of group contingencies in organizational behavior management

Businesses lose money every year due to employee absences. The purpose of the study was to evaluate a group contingency based lottery incentive system. Twenty behavior therapists employed at a non-profit organization were assigned to 10 groups of two, each with a supervisor as the team leader. Teams were eligible for lottery-based incentives based on the average weekly attendance rate. Results indicated that the employees had a higher percentage of sessions attended during the group contingency phase than during the baseline, agency initiated incentive program and the initial reversal back to baseline. Given that the attendance rates did not decrease to baseline levels during the reversal, one could argue that attendance behavior was influenced by contingency specifying stimuli during the intervention rather than the reinforcement contingency itself. All the participants indicated in the social validity questionnaire that they considered themselves to be "rule followers." Contingency specifying stimuli as the mechanism of behavior change is a cost effective intervention that requires minimal response effort to implement