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Electromyographic responses at the neuromuscular fatigue threshold
D J Pavlat1, T J Housh, G O Johnson
1Human Performance Laboratory, University of Nebraska, Lincoln 68588-0229, USA.
The Journal of Sports Medicine and Physical Fitness
|March 1, 1995
Summary
This study found that the electromyographic fatigue threshold (EMGFT) in the vastus lateralis muscle shows neuromuscular fatigue during continuous cycling. The EMGFT power output was comparable to the maximal oxygen uptake power output.
Area of Science:
- Exercise Physiology
- Sports Science
- Biomechanics
Background:
- Neuromuscular fatigue is a critical factor limiting exercise performance.
- The electromyographic fatigue threshold (EMGFT) is proposed as a sustainable exercise intensity.
- Understanding EMGFT's relationship with maximal aerobic capacity is essential for training.
Purpose of the Study:
- To investigate vastus lateralis electromyographic (EMG) responses during exhaustion at the EMGFT.
- To determine the power output of EMGFT relative to VO2max.
- To assess if EMGFT can be maintained without neuromuscular fatigue.
Main Methods:
- Fifteen adult males underwent EMGFT and continuous exhaustion cycling tests.
- A subsample (n=10) completed an incremental cycle ergometer test to determine VO2max.
- Surface EMG of vastus lateralis was recorded during cycling.
Main Results:
- EMGFT averaged 286 +/- 40W with a 250 +/- 85 sec time to exhaustion.
- A significant positive slope in iEMG versus time was observed during exhaustion at EMGFT.
- EMGFT power output (296 +/- 45W) was not significantly different from VO2max power output (282 +/- 47W).
Conclusions:
- The EMGFT is not sustainable without evidence of neuromuscular fatigue.
- EMGFT represents a power output comparable to VO2max.
- These findings challenge the concept of EMGFT as a fatigue-free intensity.