Sharon A. Evans

Electromyographic fatigue thresholds of the superficial muscles of the quadriceps femoris

The purpose of this investigation was to compare the thresholds of neuromuscular fatigue determined simultaneously from the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles using the electromyographic fatigue threshold (EMGFT) test, Eight adult volunteers [mean (SD) age, 33 (10) years] served as subjects for this investigation. The results of a one-way repeated measured ANOVA indicated that there was a significant (P < 0.05) difference among the mean EMGFT values for the VL [248(31)W], VM [223(43)W] and RF [220(30)W] muscles. Tukey post-hoc comparisons indicated that the EMGFT for the RF was significantly (P < 0.05) lower than that of the VL. These findings suggested that during cycle ergometry there is a dissociation in neuromuscular fatigue characteristics of the superficial muscles of the quadriceps femoris group.

Factors affecting the estimation of physical working capacity at the fatigue threshold

The purpose of this study was to investigate potential improvements in the methodology associated with the Physical Working Capacity at the Fatigue Threshold (PWCFT) test including: (1) the use of a continuous test protocol; (2) the use of a treadmill; (3) the use of a bipolar EMG lead system for noisy electronic environments; and (4) the potential for residual fatigue from tests repeated 24 hours apart. The results of the continuous test protocol (mean +/- S.D. = 210 +/- 73 watts) correlated well (r = 0.856) with the original discontinuous technique (222 +/- 83 watts) and there was no significant (p greater than 0.05) difference between the mean values (t = 1.146). Treadmill testing required a bipolar lead system to counteract the electrical noise generated by the treadmill motor. The heart rate values which corresponded to PWCFT on the treadmill (mean +/- s.d. = 164 +/- b.p.m.) and bicycle ergometer (153 +/- 18 b.p.m.) were highly correlated (r = 0.833) and there was no significant (p greater than 0.05) difference between the mean values (t = 2.22). The use of a bipolar lead EMG system on the bicycle ergometer resulted in significantly (p less than 0.05) smaller voltage for any given power output, and the PWCFT exhibited a low to moderate correlation (r = 0.60) with PWCFT derived from a unipolar arrangement. The test-retest results of discontinuous PWCFT measurements performed 24 hours apart on the bicycle ergometer were correlated at r = 0.812 with no significant (p greater than 0.05) difference (t = 0.52) between the mean values (test = 198 +/- 60; retest = 191 +/- 63 watts).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of ammonium chloride and sodium bicarbonate ingestion on the physical working capacity at the fatigue threshold

SummaryThe purpose of this investigation was to examine the effect of ammonium chloride (NH4Cl) and sodium bicarbonate (NaHCO3) ingestion on the physical working capacity at the fatigue threshold (PWCFT). Eighteen adult males (mean age, SD=23, 2 years) volunteered for two experiments (experiment 1,n=9 ; experiment 2,n=9). In both experiments, the subjects orally ingested 0.3 g · kg−1 body weight of NH4Cl and NaHCO3 over a 3-h period in random order on days separated by 72 h or more. In experiment 1, following ingestion of the substance, the subjects performed a discontinuous incremental cycle ergometer test to the onset of PWCFT which was estimated from integrated electromyography voltages at the vastus lateralis muscle. In experiment 2, the subjects performed a continuous PWCFT test. The results of these experiments indicated that NH4Cl and NaHCO3 ingestion had no significant (P>0.05) effect on PWCFT (experiment 1: NH4Cl=257, SD 26 W; NaHCO3=256, SD 22 W;t=0.06;r=0.866; experiment 2: NH4Cl=231, 14 W; NaHCO3=216, 16 W;t=1.78;r=0.857).

The effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold

SummaryThe purpose of this investigation was to determine the effect of glycogen depletion and super-compensation on the physical working capacity at the fatigue threshold (PWCFT). Ten adult males (mean age 23 years, SD 3) volunteered as subjects for this study. During the first laboratory visit the subjects performed a maximal bicycle ergometer test for the determination of maximum oxygen consumption

Validity of skinfold equations for estimating body density in youth wrestlers

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Neuromuscular fatigue thresholds of the vastus lateralis, vastus medialis and rectus femoris muscles

. Between 48 and 72 h later, the subjects pedaled to exhaustion at a power output which corresponded to a mean of 76% of

Weight Loss Behavior in High School Wrestling: Wrestler and Parent Perceptions

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