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Barley has been receiving increased attention as a human food due to the health benefits associated with β-glucan fiber and its potential as a low glycemic index (GI) functional food. Research has shown a relationship between the physico-chemical properties of β-glucan and the physiological effects, which may be altered by processing. However, it is not known if the physiological effects of consuming barley are affected by variations in chemical composition among cultivars or by common processing methods such as pearling or milling. The primary objective of this thesis was to characterize the effects of differences in cultivar starch and fibre content, level of pearling and milling on the GI, satiety and the physico-chemical properties of β-glucan. Nine barley cultivars varying in starch-type and β-glucan content were studied in three experiments in separate groups of ten healthy participants. Blood glucose and satiety ratings were measured and the GI was calculated. Total starch, total fibre, β-glucan, molecular weight (MW), solubility and β-glucan viscosity were determined in vitro. Results showed that GI varied by cultivar (CDC-Fibar, 26 ± 3 vs. AC-Parkhill, 35 ± 4, P < 0.05) and pearling (WG, 26 ± 4 vs. WP 35 ± 3, P < 0.05). When two cultivars were milled and processed to wet pasta the GI increased by 184% (P < 0.05). The pearled wet pasta had a significantly lower GI compared to the whole grain (P < 0.05). Boiled barley kernels tended to elicit greater satiety than white bread, but the difference was not significant. In both the boiled barley kernels and the wet pasta, pearling did not affect the MW, viscosity and solubility. MW did not significantly differ between cultivars but solubility and viscosity did (P < 0.05). The wet pasta had significantly lower MW, solubility, viscosity but not β-glucan content than the boiled barley kernels (P < 0.05). In conclusion, pearling did not have an effect but milling and extruding resulted in significant reduction in MW, solubility and viscosity. The GI of barley is influenced significantly by cultivar, pearling and milling. Further studies are required to determine the effect on satiety.

Barley has been receiving increased attention as a human food due to the health benefits associated with β-glucan fiber and its potential as a low glycemic index (GI) functional food. Research has shown a relationship between the physico-chemical properties of β-glucan and the physiological effects, which may be altered by processing. However, it is not known if the physiological effects of consuming barley are affected by variations in chemical composition among cultivars or by common processing methods such as pearling or milling. The primary objective of this thesis was to characterize the effects of differences in cultivar starch and fibre content, level of pearling and milling on the GI, satiety and the physico-chemical properties of β-glucan. Nine barley cultivars varying in starch-type and β-glucan content were studied in three experiments in separate groups of ten healthy participants. Blood glucose and satiety ratings were measured and the GI was calculated. Total starch, total fibre, β-glucan, molecular weight (MW), solubility and β-glucan viscosity were determined in vitro. Results showed that GI varied by cultivar (CDC-Fibar, 26 ± 3 vs. AC-Parkhill, 35 ± 4, P < 0.05) and pearling (WG, 26 ± 4 vs. WP 35 ± 3, P < 0.05). When two cultivars were milled and processed to wet pasta the GI increased by 184% (P < 0.05). The pearled wet pasta had a significantly lower GI compared to the whole grain (P < 0.05). Boiled barley kernels tended to elicit greater satiety than white bread, but the difference was not significant. In both the boiled barley kernels and the wet pasta, pearling did not affect the MW, viscosity and solubility. MW did not significantly differ between cultivars but solubility and viscosity did (P < 0.05). The wet pasta had significantly lower MW, solubility, viscosity but not β-glucan content than the boiled barley kernels (P < 0.05). In conclusion, pearling did not have an effect but milling and extruding resulted in significant reduction in MW, solubility and viscosity. The GI of barley is influenced significantly by cultivar, pearling and milling. Further studies are required to determine the effect on satiety.

This study was undertaken to examine the effects of ingestion of different concentrations of carbohydrate (CHO) (H20, 6, 12, and 18 g/100ml- WP, CHO-6, CH0-12, and CH0--18, respectively) on gastric emptying, muscle glycogen metabolism, and performance. Ten trained male cyclists performed four trials of 105 min of continuous cycling at 70% of VO2max. In a fifth trial the subjects completed seven 15-min rides at 70% of VO2max with three min rest between each ride. In all five trials the submaximal rides were followed by an all-out, self-paced 15-min "performance" ride on an isokinetic ergometer (Fitron) interfaced with a computer which calculated the total work output. Every 15 min the men consumed approximately 150 ml (8.5 ml/kg/hr) of one of the four test solutions (in the intermittent trial the men consumed the CHO-12 solution). Blood samples were taken every 15 min for glucose and insulin determination. Muscle biopsies were obtained from the vastus lateralis at 0 and 105 min in the WP, and the CHO-12 continuous and intermittent trials. Biopsy samples were assayed for glycogen, and sectioned and stained for myosin ATPase and glycogen to determine single fiber depletion patterns. Gastric residue was determined by intubation following the performance ride. The volume of drink emptied in the CHO-12 and CHO-18 trials was significantly less compared to both the WP and CHO-6 trials, and the volume emptied in the CHO-18 trial was less than in the CHO-12. There were no differences in glycogen use between the water and the two CHO-12 trials. Single fiber depletion patterns showed a trend toward a greater depletion of type I fibers but were not influenced by CHO ingestion. Blood glucose was significantly elevated at 105 min in both CHO-12 and the CHO-18 trials compared to the WP trial. CHO oxidation in both CHO-12 and the CHO-18 trials was significantly higher in the performance ride. Work output in both the CHO-12 trials was significantly elevated compared to the WP. These data demonstrate that 12 and 18% CHO solutions retarded gastric emptying, but that adequate CHO was delivered to enable enhanced performance in the CHO-12 trials. The fact that glycogen sparing was not observed suggests that the improved performance may have been due to the maintenance of blood glucose. Single fiber depletion patterns did not explain the performance benefits observed with CHO ingestion. / Human Performance Laboratory

There is no abstract available for this dissertation. / Human Performance Laboratory

To determine whether pre-exercise muscle glycogen levels influence the ergogenic benefits derived from carbohydrate (CHO) feedings during exercise, eight experienced cyclists completed four, 1680 kJ isokinetic cycling trials as quickly as possible. Trials were conducted under the following pre-exercise muscle glycogen (vastus lateralis) and feeding conditions: 1) high glycogen (180.2 ± 9.7 mmol•kg ww-1) with carbohydrate feedings during exercise (HGCHO trial), 2) high glycogen (170.2 ± 10.4 mmol•kg ww-1) with placebo feedings during exercise (HG-PLA trial), 3) low glycogen (99.8 ± 6.0 mmol•kg ww-1) with carbohydrate feedings during exercise (LG-CHO trial), and 4) low glycogen (109.7 ± 5.3 mmol-kg ww-1) with placebo feedings during exercise (LG-PLA trial). The placebo feedings contained no CHO. The CHO feedings provided 116 ± 6 g CHO•trial-1 and prevented the fall in serum glucose that occurred during both placebo trials. Performance times for the HG-CHO, HGPLA, LG-CHO, and LG-PLA trials averaged 117.18 ± 1.44, 118.67 ± 1.84, 121.18 ± 1.88 (P<0.05 vs. HG-CHO), and 122.91 ± 2.46 (P<0.05 vs. HG-CHO, HG-PLA) min, respectively. There were no between trial differences in relative V02 (75 ± 2 % of V02 max) or self-selected pace (8.42 ± 0.14 min-120 kJ-1) during the initial 1200 kJ of exercise. During the remaining 480 kJ, pace was similar under the HG-CHO, HG-PLA, and LG-CHO conditions (8.59 ± 0.14 min-1 20 kJ-1) but was significantly slower over the final 240 kJ of the LG-PLA trial (9.67 ± 0.43 min. 120 kJ-1). In conclusion, when pre-exercise muscle glycogen levels were low, CHO feedings enabled subjects to maintain their optimal pace throughout the exercise bout, but when pre-exercise glycogen levels were elevated, CHO feedings provided no ergogenic benefit. / Human Performance Laboratory

It has been widely recognized that aging will cause a profound decrease in glucose tolerance end increase insulin resistance. These changes have been found to occur at a relatively early age. Narimiya [54], has documented these changes in younger rots end has shown alterations in glycogen metabolism to occur prior to nine months of age. Exercise in the form of running has been shown to attenuate these changes. In Vivo, glucose, insulin end muscle glycogen have interrelated functions. The role of muscle glycogen is to provide energy for the muscle's contractile process. Insulin is needed at rest to allow glucose to enter the muscle and be stored as glycogen. The purpose of this study is to pinpoint when changes in glycogen metabolism occur while looking at the influence of exercise end weight restriction on the process. METHODS: Male Sprague Dawley rats ages 1.5-4.0 months of age were divided into three groups control (CN), pairfed (PF), and exercise trained (ET). The ET cages were equipped with voluntary running wheels attached to an automatic revolution counter. At 1.5 months, a group of controls were sacrificed and treated as the 4 mo. animals described below. Following training the hindlimbs of CN, ET, end PF were surgically isolated and glucose uptake examined by perfusing them with a bovine blood preparation, which contained insulin and glucose. Pre and post samples of the soleus, plantaris, and red and white vastus were removed and assayed for glycogen. RESULTS: The 1.5 mo. CN had significantly greater glucose uptake then any other group for both the insulin and non-insulin infused groups. The ET had significantly greater uptake than the other 4 mo. groups at 90 and 120 min in the insulin infused group. In the 1.5 mo. CN when insulin is not present all muscles will break down glycogen. When insulin is present, glycogen is used in all but the white vastus. In the 4 mo. CN all muscles except the soleus break down glycogen. In the ET the glycogen breakdown pattern is similar regardless of whether insulin is present or not. In the PF, glycogen breakdown is depressed and decidely different from the other treatment groups. CONCLUSIONS: There is an age dependent decrease in glucose tolerance and insulin resistance at or before 4 mo. of age. Training prevented some of this loss but did not stop the decline. Weight restriction had a nominal, if any, benefit in reducing insulin resistance and raising glucose tolerance with aging.

This study was designed to investigate the relationship between dietary carbohydrate consumption and muscle glycogen storage during five days of intense training. Ten highly trained distance runners performed two diet-training regimens. Training consisted of running 1.5 times each runner's average daily training distance (~20 km) at ~80% Vo2 max. During one of these intense training periods the runners ate slightly more carbohydrate (8.0 g•kg•d-1) than was required to meet the energy requirements of exercise and normal activity (EQ-CHO). During the second regimen (LO-CHO) the runners ate approximately half (3.9 g•kg•d-1) as much carbohydrate as in the previous regimen. Each regimen was preceded by a three day control period during which carbohydrate intake was maintained at 6.2 g•kg•d-1 and training was reduced to 80% of the runners normal training distance. At the end of each regimen the runners rested for three days and carbohydrate consumption was maintained at 3.8 g•kg•d-1.Compared to the EQ-CHO regimen oxygen consumption measured during standard exercise tests performed at 65% (SET 80) and 80% (SET80) of Vo2 max was greater during the LO-CHO regimen. Corresponding respiratory exchange ratios were lower during these tests. Overall (12.9 + 0.4 vs 13.7+ 0.5 units) and leg (13.3 + 0.3 vs 14.4 + 0.5 units) ratings of perceived exertion were higher during the SET80 at the end of the LO-CHO regimen. Total muscle glycogen levels were lower following the LO-CHO regimen (90.6 + 8.8 vs 66.4 + 7.8 mmol•kg-1 w.w. for the EQ-CHO vs LO-CHO regimens). A linear relationship was observed between histochemical and direct chemical analysis of muscle glycogen content (r=0.93). Resting muscle glycogen content was the same in type I, IIA and IIB fibers before the intense training period of both regimens. The glycogen content of type I, IIA and IIB fibers was lower after the LO-CHO regimen. Frequency distribution analysis of the glycogen content in individual fibers revealed that ~27% of type I fibers, 17% of type IIA fibers and 0% type IIB fibers had optical densities below 0.2 units (54 g•kg•d-1) following the intense training period of the LO-CHO regimen. Glycogen repletion during the three days of rest was greater after the LO-CHO regimen (22.2 vs 56.5 mmol•kg-1 w.w. for the EQ-CHO vs LO-CHO regimens).These data indicate that inadequate dietary carbohydrate consumption during successive days of intense training leads to incomplete glycogen repletion and selective glycogen depletion from type I muscle fibers. These events produce a greater perception of effort and decreased running economy during exercise. / Human Performance Laboratory