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The relationships among endurance performance measures as estimated from VO2PEAK, ventilatory threshold, and electromyographic fatigue threshold: a relationship design.

Graef JL, Smith AE, Kendall KL, Walter AA, Moon JR, Lockwood CM, Beck TW, Cramer JT, Stout JR - Dyn Med (2008)

Bottom Line: The resulting slopes from each successive work bout were used to calculate EMG(FT).Furthermore, the mean workload at VT was 130.7 +/- 37.8 W compared with 134.1 +/- 43.5 W at EMG(FT) (p > 0.05) with a strong correlation between the two variables (r = 0.766).As a result of these findings, the EMG(FT) test may provide an attractive alternative to estimating VT.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Health and Exercise Science, University of Oklahoma, Huston Huffman Center, 1401 Asp Avenue, Norman, OK 73019, USA. Jennifer.L.Graef-1@ou.edu

ABSTRACT

Background: The use of surface electromyography has been accepted as a valid, non-invasive measure of neuromuscular fatigue. In particular, the electromyographic fatigue threshold test (EMG(FT)) is a reliable submaximal tool to identify the onset of fatigue. This study examined the metabolic relationship between VO(2PEAK), ventilatory threshold (VT), and the EMGFT, as well as compared the power output at VO(2PEAK), VT, and EMG(FT).

Methods: Thirty-eight college-aged males (mean +/- SD = 22.5 +/- 3.5 yrs) performed an incremental test to exhaustion on an electronically-braked cycle ergometer for the determination of VO(2PEAK) and VT. Each subject also performed a discontinuous incremental cycle ergometer test to determine their EMG(FT) value, determined from bipolar surface electrodes placed on the longitudinal axis of the vastus lateralis of the right thigh. Subjects completed a total of four, 2-minute work bouts (ranging from 75-325 W). Adequate rest was given between bouts to allow for subjects' heart rate to drop within 10 beats of their resting heart rate. The EMG amplitude was averaged over 10-second intervals and plotted over the 2-minute work bout. The resulting slopes from each successive work bout were used to calculate EMG(FT).

Results: Power outputs and VO2 values from each subject's incremental test to exhaustion were regressed. The linear equations were used to compute the VO2 value that corresponded to each fatigue threshold. Two separate one-way repeated measure ANOVAs indicated significant differences (p < 0.05) among metabolic parameters and power outputs. However, the mean metabolic values for VT (1.90 +/- 0.50 l.min-1) and EMG(FT)VO2(1.84 +/- 0.53 l.min-1) were not significantly different (p > 0.05) and were highly correlated (r = 0.750). Furthermore, the mean workload at VT was 130.7 +/- 37.8 W compared with 134.1 +/- 43.5 W at EMG(FT) (p > 0.05) with a strong correlation between the two variables (r = 0.766).

Conclusion: Metabolic measurements, as well as the power outputs at VT and EMG(FT), were strongly correlated. The significant relationship between VT and EMG(FT) suggests that both procedures may reflect similar physiological factors associated with the onset of fatigue. As a result of these findings, the EMG(FT) test may provide an attractive alternative to estimating VT.

No MeSH data available.


Related in: MedlinePlus

Determination of EMGFT. a. Describes the relationship between EMG amplitude and time for the four power outputs used in the EMGFT test. The greatest slope was a result from the highest power output. b. Depicts the relationship for the power outputs versus slope coefficients with the y-intercept defined as the EMGFT.
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Figure 1: Determination of EMGFT. a. Describes the relationship between EMG amplitude and time for the four power outputs used in the EMGFT test. The greatest slope was a result from the highest power output. b. Depicts the relationship for the power outputs versus slope coefficients with the y-intercept defined as the EMGFT.

Mentions: Participants returned 24–48 hours after the GXT to perform the EMGFT test. Following a five-minute warm-up on an electronically-braked cycle ergometer (Quinton Corival 400), participants completed four two-minute cycling bouts at incrementally ascending workloads (75 W–300 W). The initial workload corresponded with the workload at which VT occurred, determined during the GXT. Adequate rest was given between bouts to allow for participants' heart rate to drop within 10 beats of their resting heart rate. The rate of rise in EMG amplitude values (EMG slope) from the four workloads were plotted over 120 seconds (Figure 1a). The EMG slope values for each of the four power outputs were then plotted to determine EMGFT (Figure 1b). The line of best fit was extrapolated to the y-axis, and the power output at which it intersected the y-axis was defined as the EMGFT. The participants completed the EMGFT protocol two times; familiarization trial and baseline.


The relationships among endurance performance measures as estimated from VO2PEAK, ventilatory threshold, and electromyographic fatigue threshold: a relationship design.

Graef JL, Smith AE, Kendall KL, Walter AA, Moon JR, Lockwood CM, Beck TW, Cramer JT, Stout JR - Dyn Med (2008)

Determination of EMGFT. a. Describes the relationship between EMG amplitude and time for the four power outputs used in the EMGFT test. The greatest slope was a result from the highest power output. b. Depicts the relationship for the power outputs versus slope coefficients with the y-intercept defined as the EMGFT.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2542988&req=5

Figure 1: Determination of EMGFT. a. Describes the relationship between EMG amplitude and time for the four power outputs used in the EMGFT test. The greatest slope was a result from the highest power output. b. Depicts the relationship for the power outputs versus slope coefficients with the y-intercept defined as the EMGFT.
Mentions: Participants returned 24–48 hours after the GXT to perform the EMGFT test. Following a five-minute warm-up on an electronically-braked cycle ergometer (Quinton Corival 400), participants completed four two-minute cycling bouts at incrementally ascending workloads (75 W–300 W). The initial workload corresponded with the workload at which VT occurred, determined during the GXT. Adequate rest was given between bouts to allow for participants' heart rate to drop within 10 beats of their resting heart rate. The rate of rise in EMG amplitude values (EMG slope) from the four workloads were plotted over 120 seconds (Figure 1a). The EMG slope values for each of the four power outputs were then plotted to determine EMGFT (Figure 1b). The line of best fit was extrapolated to the y-axis, and the power output at which it intersected the y-axis was defined as the EMGFT. The participants completed the EMGFT protocol two times; familiarization trial and baseline.

Bottom Line: The resulting slopes from each successive work bout were used to calculate EMG(FT).Furthermore, the mean workload at VT was 130.7 +/- 37.8 W compared with 134.1 +/- 43.5 W at EMG(FT) (p > 0.05) with a strong correlation between the two variables (r = 0.766).As a result of these findings, the EMG(FT) test may provide an attractive alternative to estimating VT.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Health and Exercise Science, University of Oklahoma, Huston Huffman Center, 1401 Asp Avenue, Norman, OK 73019, USA. Jennifer.L.Graef-1@ou.edu

ABSTRACT

Background: The use of surface electromyography has been accepted as a valid, non-invasive measure of neuromuscular fatigue. In particular, the electromyographic fatigue threshold test (EMG(FT)) is a reliable submaximal tool to identify the onset of fatigue. This study examined the metabolic relationship between VO(2PEAK), ventilatory threshold (VT), and the EMGFT, as well as compared the power output at VO(2PEAK), VT, and EMG(FT).

Methods: Thirty-eight college-aged males (mean +/- SD = 22.5 +/- 3.5 yrs) performed an incremental test to exhaustion on an electronically-braked cycle ergometer for the determination of VO(2PEAK) and VT. Each subject also performed a discontinuous incremental cycle ergometer test to determine their EMG(FT) value, determined from bipolar surface electrodes placed on the longitudinal axis of the vastus lateralis of the right thigh. Subjects completed a total of four, 2-minute work bouts (ranging from 75-325 W). Adequate rest was given between bouts to allow for subjects' heart rate to drop within 10 beats of their resting heart rate. The EMG amplitude was averaged over 10-second intervals and plotted over the 2-minute work bout. The resulting slopes from each successive work bout were used to calculate EMG(FT).

Results: Power outputs and VO2 values from each subject's incremental test to exhaustion were regressed. The linear equations were used to compute the VO2 value that corresponded to each fatigue threshold. Two separate one-way repeated measure ANOVAs indicated significant differences (p < 0.05) among metabolic parameters and power outputs. However, the mean metabolic values for VT (1.90 +/- 0.50 l.min-1) and EMG(FT)VO2(1.84 +/- 0.53 l.min-1) were not significantly different (p > 0.05) and were highly correlated (r = 0.750). Furthermore, the mean workload at VT was 130.7 +/- 37.8 W compared with 134.1 +/- 43.5 W at EMG(FT) (p > 0.05) with a strong correlation between the two variables (r = 0.766).

Conclusion: Metabolic measurements, as well as the power outputs at VT and EMG(FT), were strongly correlated. The significant relationship between VT and EMG(FT) suggests that both procedures may reflect similar physiological factors associated with the onset of fatigue. As a result of these findings, the EMG(FT) test may provide an attractive alternative to estimating VT.

No MeSH data available.


Related in: MedlinePlus