This thesis examines the ontogeny of plasma sodium regulation (an indicator of osmoregulatory ability), current or rheotactic response (an indicator of emigration timing) and salinity preference in juvenile coho salmon (Oncorhynchus kisutch). The purpose of the study was to determine if there are inherited differences in the development of these traits between coastal and interior British Columbia populations of coho. An interior (Cold water River) and a coastal (Rosewall Creek-Big Qualicum River) population were monitored for the above traits throughout the year. Both wild and laboratory groups were included in the study. The laboratory raised populations were divided into two incubation treatment groups: one incubated under a coastal temperature regime, and the other incubated under an interior temperature regime. There were no differences in the development of sodium regulatory ability between wild populations when the data were sorted by coho weight. Coastal coho, however, physiologically smolted after one year in the natal streams, while interior coho smolted after at least two years of freshwater growth. No obvious differences were noted between wild resident populations in the timing of downstream movement or the shift in salinity preference from hypotonic to isotonic and hypertonic salinities. Both of these behavioural responses typically occurred in the spring (April-May) of each year. Fyke net catches, however, sugqested that, in addition to the spring emigrations observed in both populations, a portion of the interior population migrated in the fall (November). No differences in the development of sodium regulatory ability were observed either within or between laboratory raised populations. Ion regulatory ability increased to a plateau in the fall and winter following emergence, and increased to smolting levels during the following spring (April-May). There were differences between coastal and interior populations in the pattern of development of both nocturnal current responses and the preference for isotonic or hypertonic salinities. Interior laboratory raised coho developed negative nocturnal rheotaxis and a preference for isotonic salinities about three months earlier (November) than laboratory raised coastal coho (late February-March). Within populations, no differences were observed in the ontogeny of these traits in the groups reared under different temperature regimes. Because these interpopulation ontogenetic behavioural differences persisted in fish reared under identical laboratory conditions, they probably have some genetic basis. Such an innate component in behaviour implies an adaptive role and in juvenile coho these behavioural traits may allow populations to use a variety of habitats at different distances from the sea, even though a major physiological schedule (in this case the development of ion regulatory capabilities) appears to be fixed within the species. Perhaps variations in migratory timing and salinity preference in juvenile coho evolved to assure survival in a relatively unstable and often severe environment by optimizing habitat use within the constraints of an overriding physiological schedule. / Science, Faculty of / Zoology, Department of / Graduate

This thesis aimed to, first, examine the effects of the addition of whey protein or casein protein to common carbohydrate-electrolyte (CE) solutions on post-exercise rehydration; second, examine the effects of various contents of whey protein in CE solutions on post-exercise rehydration; and third, investigate the mechanisms on the increased fluid retention after the ingestion of CE plus whey protein solutions. / The first study (Chapter 4) of this thesis examined the effects of CE solution added with a certain amount of whey or casein protein on post-exercise rehydration. Ten young healthy males (mean ± SEM, age: 20.7 ± 0.4 years; body weight (BW): 65.4 ± 2.0 kg; maximal oxygen uptake (VO₂ₘₐₓ): 60.7 ± 1.9 mL·kg⁻¹·min⁻¹) were recruited in this study. Three main experimental trials were conducted in a randomized single-blinded crossover design and separated by at least 7 days between any two of them. In each main trial, subjects ran for 60 min at 65% VO₂ₘₐₓ on a treadmill in a warm and humid environment (24 °C, 60% relative humidity (RH)), which was followed by a 4-hour recovery period. During recovery, the subjects were provided with either a common CE solution, or a CE with whey protein (CW) solution, or a CE with casein protein (CC) solution. The three solutions were matched for energy and electrolyte content and were provided in six equivalent volumes at 30 min intervals with a total volume equivalent to 150% of their BW loss. The nude BW, urine samples, and capillary blood samples were collected before and after exercise and at the end of each hour during recovery. After exercise, the subjects lost approximately 2.3% of their pre-exercise BW in all trials. Total urine volume after recovery was higher in the CE and CC trials than in the CW trial (CE vs. CW vs. CC: 1184 ± 120 mL vs. 1005 ± 68 mL vs. 1256 ± 130 mL, p < 0.05), which induced greater fluid retention in CW trial compared with both CE and CC trials (CE vs. CW vs. CC: 46.9 ± 5.2% vs. 54.9 ± 2.9% vs. 45.8 ± 5.5%, p < 0.05). By the end of recovery, the urine specific gravity (USG) was lower in the CE trial than in both CW and CC trials (CE vs. CW vs. CC: 1.002 ± 0.001 g·mL⁻¹ vs. 1.004 ± 0.001 g·mL⁻¹ vs. 1.004 ± 0.000 g·mL⁻¹, p < 0.05). In addition, the urine osmolality was lower in the CE trial than in both CW and CC trials after recovery (CE vs. CW vs. CC: 111 ± 18 mmol·kg⁻¹ vs. 181 ± 14 mmol·kg⁻¹ vs. 195 ± 23 mmol·kg⁻¹, p < 0.05). However, no difference was found in the changes of plasma volume among trials throughout recovery. These results suggested that during a 4-hour recovery after 60 min run which induced about 2% BW loss, the CE plus whey protein solution was more effective in fluid retention compared with the isocaloric CE or CE plus casein protein solution. / The second study (Chapter 5) was conducted to examine the effects of various contents of whey protein in CE solutions on post-exercise rehydration; meanwhile, the mechanisms on the greater fluid retention after the ingestion of CE plus whey protein solutions were investigated as well. Ten young healthy males (mean ± SEM, age: 22.0 ± 0.7 years; BW: 64.5 ± 1.9 kg; VO₂ₘₐₓ: 59.8 ± 1.9 mL·kg⁻¹·min⁻¹) finished five main experimental trials in a randomized single-blinded crossover manner and separated by at least 7 days. After a 60-min run at 65% VO₂ₘₐₓ on a treadmill in each main trial, a 4-hour recovery period was carried out. During recovery, five solutions of 1) a CE solution with high CHO content (CE-H); 2) a CE solution with low CHO content (CE-L); 3) a CE solution with high content of whey protein (CW-H); 4) a CE solution with medium content of whey protein (CW-M); and 5) a CE solution with low content of whey protein (CW-L) were consumed by the subjects randomly. The electrolyte content was matched, whereas CE-H, CW-H, CW-M, and CW-L solutions were matched for energy density, CE-L and CW-H solutions were matched for CHO content. The total volume consumed by subjects was 150% of the BW loss, and the solutions were provided in six equal volumes at 30 min intervals during recovery. The nude BW, urine samples, and capillary and venous blood samples were obtained before and after exercise and at the end of each hour during recovery. The results showed that the subjects lost about 2.2% of BW after exercise. By the end of the recovery, the total urine volume was smaller in the CW-M trial than in the CE-H trial (CE-H vs. CW-M: 1295 ± 103 mL vs. 1049 ± 130 mL, p < 0.05), whereas the CW-H trial was smaller than the CE-H, CE-L, and CW-L trials (CE-H vs. CE-L vs. CW-L vs. CW-H: 1295 ± 1033 mL vs. 1284 ± 90 mL vs. 1141 ± 58 mL vs. 891 ± 73 mL, p < 0.01). The less urine production in the CW-M and CW-H trials resulted in a greater fluid retention compared with CE-H, CE-L, and CW-L trials (CE-H vs. CE-L vs. CW-L vs. CW-M vs. CW-H: 38.4 ± 5.2% vs. 36.1 ± 4.3% vs. 43.0 ± 3.8% vs. 51.0 ± 5.7% vs. 55.4 ± 3.8%, p < 0.05). The CE-H and CE-L trials showed lower USG and urine osmolality compared with the CW-L, CW-M, and CW-H trials at the end of recovery (p < 0.05). In addition, the plasma osmolality of the CE-L trial was lower than that of the CW-L, CW-M, and CW-H trials at the 1st hour of recovery (CE-L vs. CW-L vs. CW-M vs. CW-H: 274 ± 4 mmol·kg⁻¹ vs. 291 ± 4 mmol·kg⁻¹ vs. 301 ± 6 mmol·kg⁻¹ vs. 293 ± 6 mmol·kg⁻¹, p < 0.05). The plasma volume was lower in the CE-L trial than that in the CW-H trial at the 2nd and 3rd hour, and the CE-L trial reached the lowest plasma volume than the other four trials by the end of recovery (p < 0.05). The aldosterone concentration was lower in both CE-H and CE-L trials compared with the CW-M and CW-H trials after recovery (CE-H vs. CE-L vs. CW-M vs. CW-H: 228 ± 100 pg·mL⁻¹ vs. 211 ± 51 pg·mL⁻¹ vs. 336 ± 85 pg·mL⁻¹ vs. 333 ± 70 pg·mL⁻¹, p < 0.05). The antidiuretic hormone (ADH) concentration was also found to be lower in the CE-L trial than in the CW-H trial at the 1st and 2nd hour of recovery (p < 0.05). However, no difference was found in plasma albumin concentrations among trials throughout recovery. The results indicated that the CE solutions with higher whey protein content retained more fluid compared with CE solutions with lower whey protein content or CE solution alone. The greater fluid retention was partly caused by the elevated aldosterone concentrations in the situations of current study. / In summary, the experimental results of this thesis found that the consumption of common CE solution plus whey protein can retain more fluid in body than isocaloric CE or CE plus casein protein solution during post-exercise recovery. CE solutions with relative higher whey protein content were more effective in fluid retention than CE solutions with lower whey protein content. Furthermore, the additive effects on fluid retention caused by whey protein supplementation were induced by the increased concentrations of plasma aldosterone. The elevated plasma osmolality and ADH concentrations maybe also played a role in the greater fluid retention. However, further studies are needed to clarify this issue. The current findings provided more evidences in this research topic and suggested some recommendations to athletes and sports enthusiasts to reach rehydration rapidly and effectively after exercise. / 本論文的研究目的包括：首先，研究在普通的碳水化合物-電解質（CE）飲料中添加乳清蛋白或酪蛋白對運動後復水的影響；其次，研究CE飲料中添加不同劑量的乳清蛋白對運動後復水的影響；再次，闡述飲用CE加乳清蛋白飲料後更能有效的將水分保留在人體內的機制。 / 實驗一（第四章）研究了在CE飲料中加入一定劑量的乳清蛋白或酪蛋白對運動後復水的影響。十位年輕、健康男性受試者（平均值 ± 標準誤，年齡: 20.7 ± 0.4 歲；體重: 65.4 ± 2.0 千克；最大攝氧量: 60.7 ± 1.9 mL·kg⁻¹·min⁻¹）自願參加本項測試。按照隨機單肓交叉設計，他們完成了三次主測試，期中任何兩次測試時間都相隔七天以上。在每一次主測試中，受試者首先在跑臺上以65%最大攝氧量的運動強度完成了60分鐘的跑步運動（運動環境控制在24攝氏度，60%相對濕度），隨後開始4小時的運動後恢復階段。在恢復過程中，受試者會分別飲用三種不同飲料中的一種。三種飲料包括：（1）普通CE飲料（CE組）；（2）普通CE飲料中添加乳清蛋白（CW 組）；（3）普通CE飲料中添加酪蛋白（CC 組）。三種飲料含有相同的能量密度及電解質濃度。受試者在每次主測試中飲用的總飲料體積為1.5倍的體重減少量，這些飲料分為6等份并每隔30分鐘由受試者飲用一份。運動前、後及在恢復階段每隔一小時收集受試者的體重（裸重）、尿液樣本、及血液樣本（指尖取血）。在三次主測試中，受試者在運動結束後減少的體重量約為運動前體重的2.3%。在4小時的恢復階段中，CE組和CC組受試者排出的尿液總體積大於CW組（CE vs. CW vs. CC: 1184 ± 120 mL vs. 1005 ± 68 mL vs. 1256 ± 130 mL, p < 0.05）。所以，恢復結束後，CW組的水分保持比例高於CE組及CC組（CE vs. CW vs. CC:46.9 ± 5.2% vs. 54.9 ± 2.9% vs. 45.8 ± 5.5%, p < 0.05）。在恢復結束時，CE組的尿比重低於CW組及CC組（CE vs. CW vs. CC: 1.002 ± 0.001 g·mL⁻¹ vs. 1.004 ± 0.001g·mL⁻¹ vs. 1.004 ± 0.000 g·mL⁻¹, p < 0.05）。另外，在恢復結束後，CE組尿滲透壓水平低於CW組及CC組（CE vs. CW vs. CC: 111 ± 18 mmol·kg⁻¹ vs. 181 ± 14mmol·kg⁻¹ vs. 195 ± 23 mmol·kg⁻¹, p < 0.05）。但是，在恢復階段，血漿容量的變化在三組中沒有顯著差異。本實驗的結果表明，完成60分鐘跑步後，受試者丟失掉約2%的體重，在之後4小時恢復階段中，飲用添加乳清蛋白的CE飲料比有相同能量密度的普通CE飲料或添加酪蛋白的CE飲料更能有效的將水分保留在體內。 / 實驗二（第五章）研究了在普通CE飲料中添加不同劑量的乳清蛋白對運動後復水的影響；同時，也研究了飲用CE加乳清蛋白飲料後更能有效的將水分保留在人體內的機制。十位年輕、健康男性受試者（平均值 ± 標準誤，年齡: 22.0 ± 0.7 歲；體重: 64.5 ± 1.9 千克；最大攝氧量: 59.8 ± 1.9 mL·kg⁻¹·min⁻¹）自願參加本項測試。按照隨機單肓交叉設計，他們完成了五次主測試，任何兩次測試的時間都相隔七天以上。在每一次主測試中，受試者首先在跑臺上以65%最大攝氧量的運動強度完成了60 分鐘的跑步運動，隨後開始4 小時的運動後恢復階段。在恢復過程中，受試者會飲用五種不同飲料中的一種。五種飲料包括：（1）普通CE飲料，含有較高的CHO濃度（CE-H組）；（2）普通CE飲料，含有較低的CHO濃度（CE-L組）；（3）普通CE飲料添加較高劑量的乳清蛋白（CW-H組）；（4）普通CE飲料添加中等劑量的乳清蛋白（CW-M組）；（5）普通CE飲料添加較低劑量的乳清蛋白（CW-L組）。五種飲料含有相同濃度的電解質，其中，CE-H，CW-H，CW-M，及CW-L組有相同的能量密度，CE-L 及CW-H 組有相同的CHO含量。在每次主測試的恢復階段，受試者飲用的飲料總體積為1.5倍的體重減少量，這些飲料分為6等份并每隔30分鐘由受試者飲用一份。運動前、後及在恢復階段每隔一小時收集受試者的體重（裸重）、尿液樣本、及血液樣本（指尖取血及靜脈取血）。運動結束後，受試者的體重減少量約為運動前體重的2.2%，五組測試中沒有顯著差異。在4小時的恢復階段後，CW-M 組受試者的尿液總體積小於CE-H組（CE-H vs. CW-M:1295 ± 103 mL vs. 1049 ± 130 mL, p < 0.05）；同時，CW-H組的尿量低於CE-H，CE-L，及CW-L組（CE-H vs. CE-L vs. CW-L vs. CW-H: 1295 ± 103 mL vs. 1284 ± 90mL vs. 1141 ± 58 mL vs. 891 ± 73 mL, p < 0.01）。相對於CE-H，CE-L，及CW-L組，較少的尿液排出量使CW-M及CW-H組能將更多的水分保留在體內（CE-H vs.CE-L vs. CW-L vs. CW-M vs. CW-H: 38.4 ± 5.2% vs. 36.1 ± 4.3% vs. 43.0 ± 3.8% vs.51.0 ± 5.7% vs. 55.4 ± 3.8%, p < 0.05）。在恢復結束後，CE-H及CE-L組的尿比重水平及尿滲透壓水平低於CW-L，CW-M，及CW-H組（p < 0.05）。另外，在恢復階段的第1小時，CE-L組的血漿滲透壓水平低於CW-L，CW-M，及CW-H組（CE-L vs. CW-L vs. CW-M vs. CW-H: 274 ± 4 mmol·kg⁻¹ vs. 291 ± 4 mmol·kg⁻¹ vs. 301 ± 6 mmol·kg⁻¹ vs. 293 ± 6 mmol·kg⁻¹, p < 0.05）。在恢復階段的第2及3小時，CE-L組的血漿容量低於CW-H組；在恢復結束時，CE-L組的血漿容量低於其它四組（p <0.05）。對于兩種體液平衡調節激素，在恢復結束時，CE-H及CE-L組的醛固酮水平低於CW-M及CW-H組（CE-H vs. CE-L vs. CW-M vs. CW-H: 228 ± 100 pg·mL⁻¹ vs. 211 ± 51 pg·mL⁻¹ vs. 336 ± 85 pg·mL⁻¹ vs. 333 ± 70 pg·mL⁻¹, p < 0.05）。在恢復階段的第1及2小時，CE-L組的抗利尿激素水平低於CW-H組（p < 0.05）。然而，五組測試中，血漿白蛋白水平在恢復階段沒有顯著差異。本實驗的研究結果表明，普通CE飲料中加入較高劑量的乳清蛋白比較低劑量的乳清蛋白更能有效的將水分保留在人體內。這種較高水平的水分保留能力與醛固酮激素水平的升高有關。 / 綜上所述，本論文的研究結果發現，在運動後的恢復階段飲用添加乳清蛋白的CE飲料比有相同能量密度的普通CE飲料或添加酪蛋白的CE飲料更能有效的將水分保留在人體內。並且，在CE飲料中加入較高劑量的乳清蛋白比較低劑量的乳清蛋白對人體內水分的保留更加有效。另外，這種較高水平的水分保留能力是由醛固酮激素水平的升高引起的。同時，較高的血漿滲透壓及抗利尿激素水平可能對這種高效的水分保留能力也有一定的促進作用，但需要更多的研究來闡述這一觀點。本論文的研究結果為運動後復水的相關研究提供了更多的理論證據，並且對運動員及運動愛好者在運動結束後如何進行快速有效的復水提出了指導及建議。 / Li, Liang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 131-149). / Abstracts also in Chinese; appendixes includes Chinese. / Title from PDF title page (viewed on 01, November, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

Adolescent athletes of this era are more pressurized than adolescents of previous generations to perform at an optimum level (Micheli & Jenkins 2001, p49). The importance of winning can result in adolescent athletes developing inappropriate nutritional practices such as neglecting hydration and consuming insufficient carbohydrate (Micheli & Jenkins 2001, p57). Consuming insufficient fluid leads to dehydration which reduces a soccer player’s ability to continue training. Consuming inadequate carbohydrate reduces performance and blood glucose levels during training. This study aimed to determine the hydration status, fluid and carbohydrate intake of male, adolescent soccer players during training. A cross-sectional study was conducted among 122 amateur male, adolescent soccer players (mean age = 15.8 ± 0.8 years; mean BMI = 20.4 ± 2.0 kg/m2). The players’ hydration status before and after training, was measured using urine specific gravity and percent loss of body weight. Their carbohydrate intake, as well as the type and amount of fluid consumed, were assessed before, during and after training. A questionnaire was administered to determine the players’ knowledge regarding the importance of fluid and carbohydrate for soccer training. The study had an 87.1% response rate. The mean environmental conditions did not predispose players to heat illness. However, the players were at risk of developing heat illness during six of the 14 training sessions. Although the mean urine specific gravity indicated that players were slightly dehydrated before and after training, 43.8% of players were very or extremely dehydrated before training and 53.6% after training. A few (3.3%) were extremely hyperhydrated before training and after training (7.0%). On average players lost less than 1% of body weight during training and less than 3% of players dehydrated more than 2%. Players consumed mainly water before (289.17 ± 206.37 ml), during (183.20 ± 158.35 ml) and after (259.09 ± 192.29 ml) training. More than 90% stated that water was the most important fluid to consume before, during and after training. Very few (4.7%) correctly stated that carbohydrate should be consumed before, during and after training. Players were found to be slightly dehydrated before and after training and therefore were not consuming enough fluids during training. Players consumed inadequate amounts and types of fluid and carbohydrate. This not only compromises their performance but also health. Players were not aware of the importance of fluid and carbohydrate for soccer training. This study is unique in that it focused on the carbohydrate and hydration practices of socioeconomically disadvantaged adolescent soccer players during training. The study sample therefore represents a high risk group about which there is limited published data both locally and internationally. This study generated important baseline information which was lacking before on the hydration status, fluid and carbohydrate intake of adolescent soccer players in South Africa. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

South African forestry workers are predisposed to dehydration due to the heavy physical activity they perform in impermeable regulation safety clothing in hot and often humid environments where the availability of a variety of suitable fluids at reasonable temperatures is limited. As dehydration reduces both physical and mental capacity the potential consequences include decreased productivity and an increased risk for injury. The aim of this cross sectional observational study was to determine the prevalence and severity of dehydration in rural forestry workers in both winter (minimum and maximum daily temperatures 3-22°C) and autumn (minimum and maximum daily temperatures 14-27°C). The convenience sample included 103 workers in autumn (Nelspruit, n=64 males, n=39 females, mean age 37.32 years, mean BMI 22.3 kg/m2) and 79 in winter (Richmond, n=68 males, n=11 females, mean age 25.85 years, mean BMI 22.2 kg/m2). The sample included chainsaw operators, chainsaw operator assistants, debarkers and stackers. The risk of heat illness was moderate in Nelspruit (average daily temperature 21.1°C 67% rh) and low in Richmond (average daily temperature 17.0°C 39% rh). The prevalence of dehydration was determined by urine specific gravity (USG) measurements. Percent loss of body weight in the course of the shift was used to determine the severity of dehydration. In Nelspruit 43% (n=43) and in Richmond 47% (n=37) of the forestry workers arrived at work dehydrated (USG>1.020 g/ml). Pre break this had increased to 49% (n=49) in Nelspruit and 55% (n=33) in Richmond. By the end of shift the number of dehydrated forestry workers had significantly increased to 64% (n=64, p≤0.001) in Nelspruit and 63% (n=42, p=0.043) in Richmond. A minimum of 21% (n=2) in Nelspruit and 23% (n=15) in Richmond of the forestry workers had lost more than 2% of their body weight which could significantly decrease work capacity and work output as well as mental and cognitive ability. Dehydration was not related to season (winter/autumn), gender or job category. In Nelspruit 23% (n=23) and in Richmond 13% (n=10) arrived at work overhydrated (USG<1.013 g/ml). Pre break this had decreased to 14% (n=14) in Nelspruit and 10% (n=6) in Richmond. By the end of shift 4% (n=4) in Nelspruit and 2% (n=1) in Richmond had remained overhydrated and without correcting for fluid and food intake, 5% (n=5) had gained over 2% of their body weight in Nelspruit while none had gained weight in Richmond. Overhydration was not related to season (winter/autumn), gender or job category. Physical symptoms at the end of shift included tiredness (24%), toothache (13%) and headaches (10%) although these did not correlate to end of shift USG readings (p=0.221). The fluid requirements for male workers (n=8) who did not eat or drink across the shift was 439 ml per hour. The contractors were unaware of how much fluid should be supplied to workers and how much fluid they actually supplied. The only fluid provided by the contractors was water at the ambient air temperature which was the main source of fluid for the majority. Some forestry workers brought a limited variety of other fluids including amahewu, tea and cold drinks to work. At least 40% of the work force investigated, started their shift already compromised to work to capacity (USG>1.020 g/ml). The prevalence of dehydration had increased by the break emphasizing the need to begin drinking early on in the shift. The majority of forestry workers were dehydrated at the end of the shift. A significant proportion was dehydrated to the extent (>2%) that both work capacity and mental ability would be significantly compromised. A select group of forestry workers were drinking excessive amounts of fluid and were therefore susceptible to potentially fatal dilutional hyponatremia especially as water was the primary source of fluid. Dehydration in both autumn and winter was identified as being a significant but preventable risk. As a consequence of overhydration, a small group of forestry workers may be susceptible to dilutional hyponatremia. Fluid intake guidelines for males of 450 ml per hour appeared to be safe and were within the recommendations of the American College of Sports Medicine. Fluid guidelines for females need investigation. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.