Thesis (M.S.)--University of Delaware, 2005. / Includes bibliographical references (leaves 52-54).

Thesis (M.S.)--University of Delaware, 2005. / Includes bibliographical references (leaves 52-54). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

The aim of this research was to investigate the influence of rehydration with carbohydrate-electrolyte solutions, during a short-tern recovery period, on hydration status, physiological responses, and subsequent endurance capacity. The first study (Chapter 4) examined whether prescribed or ad libitum rehydration with a carbohydrate-electrolyte solution (CHO-E), during 4 h recovery from prolonged, submaximal running would influence the subsequent endurance capacity. Five women and two men performed the "recovery" protocol consisting of a 90 min run at 70%VO2 max on a level treadmill (TI) followed by 4 h rehydration-recovery (REC), and then an open-ended run to exhaustion at 70%VD2 max (1'2) as a measure of their endurance capacity, on two occasions, at least 7 days apart. During the REC, subjects were allowed to drink a 6.9% CHO-E ad libitum (AL) on one occasion. On the other occasion, the volume of the same fluid was prescribed (PI) from calculations of the body mass lost during TI. During T2, in the PI trial, the run time to exhaustion was 16% longer (P < 0.05) than during T2 in the AL nial (69.9 ± 9.1 vs. 60.2 ± 10.2 min). Thus, ingestion of a prescribed volume of CHO-E after prolonged exercise, calculated to replace the body fluid losses, restored endurance capacity to a greater extent than ad libitum rehydration during the REC. The second study (Chapter 5) investigated the influence of ingesting 50 g of carbohydrate (CHO) immediately after exercise, either with subsequent serial CHO feeding or water ingestion during the REC from prolonged, submaximal running on rehydration and subsequent endurance capacity. Eight male subjects performed the "recovery" protocol [i.e. 90 min run at 70% V02 max (TI), 4 h rehydration-recovery (REC), and open-ended run at 70% V02 max (T2)] on two occasions. During the REC, subjects ingested a prescribed volume of fluid equal to the body mass lost during TI in both conditions. Subjects ingested 50 g of CHO from a 6.9% CHO-E 15 min after TI on both occasions as their first prescribed fluid intake. Thereafter, subjects drank either the same solution (CE) or water CW) at each hour after TI during the REC. During T2, the run time to exhaustion was 54.2 ± 9.2 min in the CE trial and 52.2 ± 6.2 min in the W trial, respectively (NS). The volume of fluid retained expressed as a percentage of the volume ingested (% rehydration) during the CE trial was greater than that of the W trial (CE: 73.5 ± 4.2% vs. W: 63.0 ± 5.7%; P < 0.05). Serial CHO feeding during the REC was associated with increased CHO oxidation and suppressed fat oxidation during subsequent exercise. Thus, ingesting -150 g of CHO in a 6.9% CHO-E over a 4 h period following prolonged running is more effective in terms of rehydration compared to the same volume of fluid containing only 50 g of CHO and water, but does not have a greater effect on subsequent endurance capacity. The third study (Chapter 6) investigated the effects of rehydration per se and CHO ingestion, during the REC, on subsequent endurance capacity. Nine male subjects performed the "recovery" protocol on two occasions. During the REC, subjects drank either a 6.9% CHO-E (CE) or a CHO-free sweetened placebo (PL) every 30 min after Tl up to the beginning of the 4 h of the REC. Volumes prescribed (ml) were equal to 200% of the body mass lost during Tl. However, the total volume of fluid ingested during the REC was only 170.8 ± 12.6% and 172.6 ± 13.8% of the body mass lost after Tl (NS). During T2, in the CE trial, the run time to exhaustion was 54% longer (P < 0.01) than during T2 in the PL trial (69.3 ± 5.5 vs. 45.0 ± 4.2 min). After the REC, subjects were in positive fluid balance by 423 ± 215 ml in the CE trial and 446 ± 239 ml in the PL trial (NS). Thus, positive fluid balance can be achieved by ingesting a prescribed volume of either a 6.9% CHO-E or a placebo solution over the REC, calculated to replace approximately 170% of the body fluid loss. Despite this similar hydration status after the recovery in both conditions, ingesting a CHO-E is more effective in restoring endurance capacity compared to the same volume of placebo solution. The fourth study (Chapter 7) was intended to examine, and verify, the effects of ingesting different amounts of CHO in the form of a CHO-E during the REC on rehydration and subsequent endurance capacity. Nine male subjects performed the "recovery" protocol on two occasions. During the REC, a fixed volume of fluid equivalent to 150% of the body mass lost during Tl was consumed. Subjects ingested 50 g of CHO from a 6.5% CHO-E 30 min after Tl on both occasions as their first prescribed fluid intake. Thereafter, subjects ingested either the same solution (CE) or a CHO-free sweetened placebo (PL) every 30 min up to the beginning of the 4 h of the REC. During T2, the run times were 56.9 ± 8.1 min in the CE trial and 65.4 ± 7.8 min in the PL trial (NS). After the REC, subjects were almost equally euhydrated (CE: 0 ± 184 ml; PL: -27 ± 120 ml) in both conditions (NS). Serial CHO feeding over the REC was accompanied by enhanced CHO oxidation and suppressed fat oxidation. In conclusion, ingesting a placebo solution containing 50 g of CHO and placebo over a 4 h period following prolonged running, calculated to replace 150% of the body fluid loss, is equally effective in achieving approximate euhydration and restoring endurance capacity compared to the same volume of CHO-E containing -167 g of CHO. The studies reported in this thesis suggest that in order to achieve euhydration during recovery, a volume of fluid substantially larger (~ 150%) than that lost must be ingested. The provision of additional CHO (-150 to 170 g) would be expected to restore the body's CHO stores to a greater extent than a smaller amount of CHO (50 g) during the REC and, thereby, improve the subsequent endurance capacity. However, this was not the case. It appears that the ingestion of large amounts of CHO, during the REC, resulted in disturbances in fat and CHO metabolism which prevented an improvement in endurance capacity during T2, after consumption of the additional CHO.

No description available.

Six lactating Ayrshire heifers were used to study the utilization of energy and the energy requirements for milk production at different stages of lactation and at different levels of production. The heifers produced an average of 5175 kg 4% FCM during lactation. Gross energetic efficiency of milk production declined from 47.58% at the beginning of lactation to 29.93% at the end of lactation. The over-all gross energetic efficiency was 36.42 ±5.55%. There was a highly significant (P < .01) positive correlation (r = 0.91) between gross energetic efficiency and 4% FCM production. High net energetic efficiencies of milk production were associated with early stages of lactation or high levels of production. The overall net energetic efficiency was 64.22 ± 5.20%. This was equivalent to a requirement of 1.187 ±0.089 megacalories digestible energy /kg 4% FCM or 270 ±20 grams TDN/kg 4% FCM. These requirements were significantly (P < .01) lower than NRC recommendations. There was a highly significant (P < .01) difference between heifers in their daily net energetic requirements. A highly significant (P < .01) positive correlation (r = 0.88) was found between net energetic efficiency and 4% FCM production. Total energy balance trials were conducted. By using an assumed maintenance requirement of 131 kcal ME/Wkg.75 to calculate the efficiency of ME utilization for milk production, the efficiency with which ME was converted to milk decreased gradually from 55.37% in early lactation to 52.11% in late lactation. Higher efficiencies of ME utilization in early stages of lactation were attributed to tissue mobilization. A significant (P < .01) difference between heifers in their efficiency of ME utilization for milk production was observed, while period effect was non-significant. By either simple linear regression analysis of ME available for milk plus maintenance on milk energy or multiple regression analysis of dietary ME on milk energy, tissue loss and metabolic body size, the efficiency of ME utilization for milk production was estimated to be 69.2 to 70.0% with a maintenance requirement of 183.5 to 184.5 kcal ME/kg .75. Multiple regression analysis showed that tissue energy was utilized for milk production with an efficiency of 98.5%. / Land and Food Systems, Faculty of / Graduate

No description available.

No description available.

Call number: LD2668 .T4 1986 W544 / Master of Science / Human Nutrition

Thesis (Ph. D. in Biomedical Engineering)--Vanderbilt University, May 2007. / Title from title screen. Includes bibliographical references.

Back pain is the second most common neurological ailment in the United States and the leading cause of pain and disability. More than 80% of the total US population experiences back-pain during their life time and the annual back pain related healthcare costs exceed 100 billion dollars. While the exact cause of low back pain (LBP) is still unknown, degeneration of the intervertebral disc (IVD) has been suggested as a primary contributor. IVD is the largest avascular tissue in the human body and it is composed of three integrated tissues (annulus fibrosus - AF, nucleus pulposus - NP and cartilaginous end plate - CEP). IVD functions as a shock-absorber during motion and provides flexibility to motion of the spine. Maintaining IVD tissue integrity is an energy demanding process. Studies have shown that mechanical loading affects cellular biosynthesis of IVD tissue and may also promote IVD degeneration. However the path to this effect is still unknown. We propose a link between mechanical loading and cell energy production which contributes to altered cellular biosynthesis. Thus, we investigated the effects of mechanical loading on IVD cell energy metabolism under various mechanical loading regimes. Porcine AF and NP cells were isolated and seeded in 2% agarose at a 5,000,000 cells/mL cell density. A custom made bioreactor was used to conduct compression experiments. The experiment groups were: 15% static compression; 30% static compression; 0.1, 1 and 2 Hz dynamic compression at 15% strain magnitude. Experiment duration was 4 hr. ATP concentration in cell-agarose construct and culture media were measured using Luciferin-luciferase method to evaluate ATP production and ATP release from cells respectively. Lactate concentration in media was measured using lactate dehydrogenase enzymatic assay. Nitrite (stable metabolite of nitric oxide - NO) concentration in media was measured by Greiss Assay. DNA content per sample was measured using fluorometric assay. DNA content per sample was used as an internal control; all compressed samples were then normalized to unstrained control group. ATP production of AF cells was up regulated by static and dynamic mechanical loading. Data suggests that AF cell response to mechanical loading is primarily loading amplitude dependent. NP cells exhibited an increased ATP production at 1 Hz dynamic loading but remained comparable to control samples at other tested conditions. AF cells produced an increase in NO production at 1-, 2 Hz dynamic loading. NO production of NP cells was up regulated by mechanical loading at all tested conditions. ATP release was up regulated at higher frequencies in AF cells. In addition to higher frequencies (1 Hz and 2 Hz) NP cell ATP release was also up regulated by 30% static compression. Thus, this study clearly illustrates that mechanical loading affects IVD cell energy production.