No description available.

The intent of this investigation was to determine the effects of contractile velocity on muscle glycogen depletion patterns during maximal isokinetic contractions.Three physically active male subjects performed maximal knee extensions and flexions using the Cybex II. Work was performed with one leg at a contractile volecity of 60 degs./sec. (1.05 rads./sec.) and the other at 300 degs./sec. (5.23 rads./sec.). Histochemical data was collected from muscle samples taken from the vastus lateralis m. of each leg. Gylcogen depletion patterns were later observed from a periodic-acid Schiffs stain (PAS) on the muscle sections. Additional muscle samples were freeze-dried for single fiber evaluation, of glycogen content. Both fast twitch (FT) and slow twitch (ST) muscle fibers were depleted of glycogen equally during each of the contractile velocities. Observations from FAS staining suggest that most of the FT fibers were depleted before the ST fibers. The results of this study indicate that the glycogen depletion pattern is independent of the velocity of contraction. This study also supports previous investigations in suggesting that the intensity of muscular contraction is one of the major determinants of the glycogen depletion pattern.

Thesis (M.S.)--Ball State University, 2009. / Title from PDF t.p. (viewed on Dec. 14, 2009). Includes bibliographical references (p. 52-54).

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

No description available.

No description available.

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Ten trained subjects were studied during and following exercise to determine the effects of fructose ingestion on muscle glycogen depletion and resynthesis. Three subjects cycled for anhour while the other six subjects completed a 3000-yard swim. The subjects ingested 12 grams of fructose before, 46 grams during, and 12 grams in the 30 minutes following the exercise. Muscle biopsies were obtained before, immediately after, and 12 hours post exercise. In -the cyclists, plasma glucose and insulin were also determined. The ingestion of fructose had no effect on the glycogen depletion during exercise. However, in the 12 hours following exercise, fructose ingestion resulted in a 41.4 mmole/kg-wet tissue increase in muscle glycogen. At the same time, the control period resulted in only a 9.53 mmole/kg-wet tissue increase in muscle glycogen. Plasma glucose and insulin levels increased during the fructose feeding. These data suggest that fructose ingestion during exercise has no effect in sparing muscle glycogen during work, but could significantly enhance the resynthesis of glycogen after work.

This study was conducted to determine the variation in stain Intensity between serial sections of muscle biopsies following a periodic acid Schiff (PAS) staining procedure, to assess the reliability of the PAS staining technique for the quantitation of the glycogen content in muscle fibers, and to evaluate the variability in fiber composition between repeated biopsies of the vastus lateralis (VL) muscle. Eight randomly located biopsies (4 right leg and 4 left leg) were obtained from the VL of each of 16 healthy males (26.1 ± 1.1 years). Serial cross sections, 10 um thick, were cut from each biopsy and stained for myosin ATPase following an acid preincubation at pH=4.30 and for glycogen using a PAS staining procedure. No significant difference existed in the fiber composition between the eight repeated biopsies taken from an individual. The variation In type I fiber percentage, expressed as the coefficient of variation, between repeated biopsies of the same leg and between the right and left VL averaged 18.6% and 17.7%, respectively. In many cases, differences of greater than 20% In the percentage of type I fibers were observed between repeated samples. These data suggest an inhomogeneity with regard to the fiber type distribution in the VL of young males and an Inability to predict the fiber composition of a muscle with a single biopsy sample.The optical densities (OD) of the same 50 type I and 50 type II fibers were determined In each of three PAS stained serial sections per biopsy using a computer integrated photometric system. Mean total, fiber type specific, and Individual fiber OD did not differ significantly between the serial sections although a variability was observed. This variability appears to be primarily due to differences In sectional thickness. The comparison of biochemically determined glycogen content (41.0 - 191.0 mmol.kg-lwet weight) to mean total OD in sections from the same samples resulted in a poor relationship (r=0.47) between the two methods for the quantification of muscle glycogen. These results Indicate a variability in PAS stain intensity between serial sections of muscle biopsies and an inability to quantify muscle glycogen concentrations with the photometric determination of OD of the PAS stain in cross sections of muscle. / School of Physical Education

The rapid determination of glycogen on indicator muscle immediately after slaughter is advantageous as it permits the prediction of a muscle’s ultimate pH (pHu) and allows the identification of high pHu meat carcasses by extrapolation. This thesis examines the development of two rapid glycogen determination methods. The first aim of this thesis was to find a new glucometer to replace the Bayer ESPRIT™ (Bayer) glucometer currently used in the Rapid pH (RpH) method. Roche’s Accuchek® Advantage II (Accuchek) and Abbott’s Medisense Optium™ (Medisense) glucometers were compared. Accuchek measurements exhibited a positive linear relationship in glucose standards made with water, RpH buffer and glucose spiked meat/buffer slurries ranging from 0 to 500 mg dL-1 (r2 = 0.999, 0.998 and 0.995 respectively). Medisense also exhibited a strong positive relationship for glucose standards made with water and RpH buffer; however, a non-linear trend in spiked meat slurries was observed. The second aim of this thesis was to explore the calibration of the KES K201 (KES Analysis Inc., NY, USA) near-infrared (NIR) diode array spectrometer to measure glycogen and pH at approximately 45 minutes after slaughter (pH45), and to predict pHu in pre-rigor M. longissimus dorsi (LD) from beef. This first required finding a reference method to calibrate against the NIR instrument. The RpH, Iodine and Bergmeyer methods were compared. Analysis of glycogen in replicate samples of three beef LD muscles at timepoints post-mortem (1, 4, 9 and 20 hours) was conducted. No significant difference in glycogen concentration was found between an enzymatic and an iodine based colorimetric method at each timepoint; however, the Iodine method was more consistent than the Bergmeyer method at all timepoints. Glucose measurements from the RpH method were consistent; however the pattern of glycogen decline at increasing timepoints post-mortem did not correspond with existing published studies. NIR spectra (538 to 1677 nm) of LD muscles from steers (n = 47), cows (n = 28) and bulls (n = 20) routinely slaughtered in a commercial abattoir were collected on-line approximately 45 minutes after slaughter. Poor results were obtained for Partial Least Squares (PLS) models generated from the mean reflectance spectra of each animal to measure glycogen and pH45, and predict pHu (r2 = 0.23, 0.37 and 0.20 respectively). A high mean square error of prediction (MSEP) for glycogen was also obtained (7.75). Validation of qualitative models generated with Generalised Partial Least Squares regression (GPLS) found that the optimum model was able to correctly categorise only 42% of high pHu samples with the remaining portion being wrongly classified as normal pHu meat. When the effect of gender was removed, only 21% of high pHu carcasses were correctly categorised. Exploratory analysis of the absorbance spectra of the LD muscles showed that a group composed predominantly of steers had a significantly lower pH45 than other existing groups. Further work is recommended for NIR to be successfully utilised on-line to measure glycogen or predict pHu in pre-rigor carcasses.