Interlimb Neuromuscular Responses During Fatiguing, Bilateral, Leg Extension Exercise at a Moderate Versus High Load

This study determined the load- and limb-dependent neuromuscular responses to fatiguing, bilateral, leg extension exercise performed at a moderate (50% one-repetition maximum [1RM]) and high load (80% 1RM). Twelve subjects completed 1RM testing for the bilateral leg extension, followed by repetitions to failure at 50% and 80% 1RM, on separate days. During all visits, the electromyographic (EMG) and mechanomyographic (MMG), amplitude (AMP) and mean power frequency (MPF) signals were recorded from the vastus lateralis of both limbs. There were no limb-dependent responses for any of the neuromuscular signals and no load-dependent responses for EMG AMP, MMG AMP, or MMG MPF (p = .301–.757), but there were main effects for time that indicated increases in EMG and MMG AMP and decreases in MMG MPF. There was a load-dependent decrease in EMG MPF over time (p = .032) that suggested variability in the mechanism responsible for metabolite accumulation at moderate versus high loads. These findings suggested that common drive from the central nervous system was used to modulate force during bilateral leg extension performed at moderate and high loads.

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Inter- and Intra-Individual Differences in EMG and MMG during Maximal, Bilateral, Dynamic Leg Extensions

Sports ◽

10.3390/sports7070175 ◽

2019 ◽

Vol 7 (7) ◽

pp. 175 ◽

Cited By ~ 5

Author(s):

John Paul V. Anders ◽

Cory M. Smith ◽

Joshua L. Keller ◽

Ethan C. Hill ◽

Terry J. Housh ◽

...

Keyword(s):

Individual Differences ◽

Repeated Measures ◽

Polynomial Regression ◽

Vastus Lateralis ◽

Regression Analyses ◽

Mean Power ◽

Mean Power Frequency ◽

Leg Extension ◽

Neuromuscular Responses ◽

Muscle Actions

The purpose of this study was to compare the composite, inter-individual, and intra-individual differences in the patterns of responses for electromyographic (EMG) and mechanomyographic (MMG) amplitude (AMP) and mean power frequency (MPF) during fatiguing, maximal, bilateral, and isokinetic leg extension muscle actions. Thirteen recreationally active men (age = 21.7 ± 2.6 years; body mass = 79.8 ± 11.5 kg; height = 174.2 ± 12.7 cm) performed maximal, bilateral leg extensions at 180°·s−1 until the torque values dropped to 50% of peak torque for two consecutive repetitions. The EMG and MMG signals from the vastus lateralis (VL) muscles of both limbs were recorded. Four 2(Leg) × 19(time) repeated measures ANOVAs were conducted to examine mean differences for EMG AMP, EMG MPF, MMG AMP, and MMG MPF between limbs, and polynomial regression analyses were performed to identify the patterns of neuromuscular responses. The results indicated no significant differences between limbs for EMG AMP (p = 0.44), EMG MPF (p = 0.33), MMG AMP (p = 0.89), or MMG MPF (p = 0.52). Polynomial regression analyses demonstrated substantial inter-individual variability. Inferences made regarding the patterns of neuromuscular responses to fatiguing and bilateral muscle actions should be considered on a subject-by-subject basis.

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Comparison of Inter- and Intra-Individual Neuromuscular Patterns of Responses During Moderate-Load Bilateral Leg Extension Exercise

Research Directs in Strength and Performance ◽

10.53520/rdsp2021.10515 ◽

2021 ◽

Vol 1 (1) ◽

Author(s):

Taylor Dinyer-McNeely ◽

Pasquale J. Succi ◽

Caleb C. Voskuil ◽

M. Travis Byrd ◽

Haley C. Bergstrom

Keyword(s):

Polynomial Regression ◽

Vastus Lateralis ◽

Mean Power ◽

Mean Power Frequency ◽

Leg Extension ◽

Linear Relationships ◽

Left Limb ◽

Neuromuscular Responses ◽

Quadratic Relationship ◽

The Right

Introduction: This study examined the electromyographic (EMG) and mechanomyographic (MMG), amplitude (AMP) and mean power frequency (MPF) responses during bilateral, leg extension exercise performed to failure at a moderate (70% one-repetition maximum [1RM]) load. Methods: Eleven men completed a 1RM and repetitions to failure at 70% 1RM of the leg extension. The EMG and MMG signals were recorded from the right and left vastus lateralis. Polynomial regression analyses were used to determine individual and composite, normalized neuromuscular responses for both limbs. Results: For EMG AMP, both limbs demonstrated positive, quadratic relationships. For EMG MPF, the right limb demonstrated a negative, cubic relationship and the left limb demonstrated a negative, quadratic relationship. For MMG AMP, the right limb demonstrated a positive, quadratic relationship and the left limb demonstrated a positive, linear relationship. For MMG MPF, both limbs demonstrated negative, linear relationships. 18-45% of the subjects demonstrated the same responses as the composite for the EMG and MMG signals. 14% of the subjects demonstrated the same direction and pattern of response for the right and left limb intra-individual responses. Conclusions: The variability in the inter- and intra-individual responses highlight the necessity to report individual neuromuscular responses when examining fatiguing resistance exercise.

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