In conclusion, the studies reported in this thesis suggested that the CHO amount, whether provided by a pre-exercise CHO meal or short-time, i.e., 3-day, CHO loading, plays a pivotal role in regulating the immune responses before, during, and after endurance exercise. Although GI and GL independently affect the exercise performance and immune responses, the amount of CHO consumed remains a determining factor. The potential benefits on immune system and endurance performance after the low GI and low GL diet (L-L) should be noted and warrant further investigation. Although the HGI and LGI meals demonstrated similar effects on endurance performance when large amount of CHO-electrolyte solution consumed during the exercise, pre-exercise LGI meal can hasten the IL-6 responses during the recovery. (Abstract shortened by UMI.) / The aim of this thesis was to investigate the influence of pre-exercise carbohydrate (CHO) meal(s) with different glycemic index (GI) and glycemic load (GL) on endurance running performance, physiological, and immune responses. / The first study (Chapter 4) examined the influence of a pre-exercise meal with different GI and GL on subsequent endurance running performance, physiological, and immune responses. Eight endurance-trained male runners completed three trials in a randomized order, separated by at least seven days. These responses were characterized by a lower CHO oxidation with a concomitant higher glycerol and FFA in the H-L trial. Consumption of a pre-exercise high CHO meal, i.e., H-H and L-L, resulted in less perturbation of circulating numbers of leukocytes, neutrophils, and T lymphocyte subsets, decreased elevation of plasma IL-6 concentrations immediately after exercise and during the 2 h recovery period when compared to the H-L trial. These responses were accompanied by an attenuated increase in plasma IL-10 concentrations and plasma cortisol concentrations at the end of 2 h recovery. It was concluded that the amount of CHO consumed 2 h before endurance exercise appears to be the main influencing factor on immune responses irrespective of its GI and GL value. / The second study (Chapter 5) examined the influence of a 3-day CHO loading with different GI and GL meals on the supercompensation status, running performance, physiological and immune responses. Nine endurance-trained male runners were recruited in this study. The procedures basically involved a 3-day CHO loading with different GI and GL meal [CHO intake (% of energy intake), GI, and GL per day are 73%, 80, and 553 for the high-GI and high-GL (H-H); 73%, 42, and 249 for the low-GI and low-GL (L-L); 31%, 78.5, and 227 for the high-GI and low-GL (H-L) respectively] after a glycogen-lowering exercise. Two hours after the breakfast on day 4, participants performed the running protocol as described in the first study. There was no difference in time to complete the 10-km TT between the two trials with high-CHO loading, i.e., H-H and L-L (51.3 +/- 5.3 min vs 48.6 +/- 1.3 min, NS). These results suggested that 3-day CHO loading with low GI and low GL (L-L) is more effective in improving endurance performance when compared to a high GI but low GL diet (H-L). It appears that the amount of CHO consumed during the 3-day CHO loading remains the key influencing factor on immune responses despite of the differences in the GI and GL value. / The third study (Chapter 6) investigated the influence of pre-exercise meal with different GI on subsequent endurance running performance and immune responses when CHO-electrolyte solution was consumed during exercise. Pre-exercise LGI meal attenuated the increases of cortisol when compared with CON and hastened the recovery of the IL-6 value to baseline when compared to that in HGI and CON trials during the first hour of the recovery. The results suggested that beside of CHO quantity (CHO content), the role of CHO quality (GI) in the diet consumed 2 h before exercise should be considered when investigating the influence of CHO supplementation on the exercise-induced transitory immunosuppressive effects. / Chen Yajun. / "August 2006." / Adviser: Stephen Wong Heung-Sang. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1597. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 199-225). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

The transition from cycling to running has been identified as one of the key determinants of success in triathlon, as it has been suggested that the cycle may affect subsequent running efficiency such that running performance is significantly altered or reduced. It is also suggested that athletes more adapted to the transition itself, rather than purely running or cycling, may be more efficient during the post-cycle running bout. The current study sought to investigate the effects of prior cycling on subsequent selected biomechanical, physiological and perceptual responses of three different athlete groups. Subjects were selected on the basis of their sporting background, and were divided into three groups – triathletes, cyclists and runners. Experimentation required subjects to perform a seven minute treadmill running protocol at 15km.h⁻¹, during which biomechanical (EMG, Stride rate, Stride length, Vertical acceleration), physiological (HR, VO₂, EE) and perceptual (RPE) responses were recorded. After resting, subjects were required to perform a twenty minute stationary cycle at 70% of maximal aerobic power (previously determined), immediately followed by a second seven minute treadmill running protocol during which the same data were collected and compared to those collected during the first run. Biomechanical responses indicate that the cycle protocol had no effect on the muscle activity or vertical acceleration responses of any of the three subject groups, while the triathlete group significantly altered their gait responses in order to preserve running economy. The triathlete group was the least affected when considering the physiological responses, as running economy was preserved for this group. The runner and cyclist groups were significantly affected by the transition, as running economy decreased significantly for these groups. Perceptual responses indicate that athletes more experienced with the transition may find the transition from cycling to running to be easier than those inexperienced in this transition. It is apparent that a high intensity cycle protocol has limited statistical impact on selected biomechanical responses, while physiological and perceptual responses were altered, during a subsequent run, regardless of athlete type. That said, the ability of transition-trained athletes to transition comfortably between disciplines was highlighted, which may have important performance implications.

This study investigated the psychobiological and pacing characteristics of the 1.5 mile run. Sixty-six males (18-27 years) performed the run, and were monitored for ratings of perceived exertion, heart rate and split times. The perceived exertion values increased in a near-linear fashion inconsistent with other measures, and thus are not considered a supportable indicator of physiological performance during the run. Pace was characterized by an initial sprint that slowed to a near-steady pace and concluded with a final sprint. The initial and final sprints were most highly related to the variance of performance time. Initially, heart rate accelerated greatly. This acceleration slowed, ending in near-maximum heart rates. The data suggested that performance may rely heavily upon anaerobic mechanisms, and that variance in previously reported correlational analyses of VO2max and 1.5 mile run performance times may be somewhat due to anaerobic mechanisms.

No abstract available. / Thesis (M.Med.Sc.)-University of KwaZulu-Natal, Durban, 2005.

Text in English / Regular exercise has significant physical and psychological health benefits yet, paradoxically, may also have harmful effects. The purpose of this study was to investigate the physical and psychological health risks of distance running, a popular participation sport in South Africa. Structural equation modelling was employed to examine the personality and motivational antecedents of running addiction and its influence, in turn, on self-reported overuse injuries and upper respiratory tract infections in 220 athletic club members. The predictors and physical health effects of customary training load were also assessed. It was found that perfectionistic concerns, Type A behaviour pattern, and task goal orientation had a direct, positive impact on running addiction, which predicted higher running injury scores. In contrast, training workload (Volume × Intensity) was inversely related to injury risk. Neither running addiction nor any training load variables influenced infectious illness susceptibility. The findings of this study indicate that maladaptive perfectionism, Type A behaviour, and achievement goal orientation may be risk factors for running addiction, which may, in turn, contribute to increased injury incidence in South African distance runners. Conversely, heavier training loads may be protective against injury occurrences in this population. The results of this research may help to enhance current understanding of the possible health hazards of distance running. This knowledge may have practical implications for the health and well-being of runners of diverse levels of ability and experience. / Psychology / D.Litt. et Phil. (Psychology)