Thesis (MSc)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: A 5 km cycling time trial (TT) demands high, sustained muscle power output and substantial oxidative and glycolytic energy delivery. The aims of this study were to firstly use the novel approach of using Peak Sustained Power Output (PSPO) as a predictor of cycling performance for variable fixed-workload testing and 5 km time trialing and whether oral creatine supplementation would affect 5 km time trial performance and metabolism. The effect of oral creatine supplementation with 20 g/day for 7 days on 5 km time trial performance and metabolism after a random-variable workload protocol (stochastic test) was investigated in a single-blind placebo controlled study. Thirteen trained male cyclists volunteered for the study that was approved by the University of Stellenbosch Research Ethics Committee. We hypothesized that Cr supplementation would affect time trial performance as well as the appearance of breakdown products of adenine nucleotides in the plasma. Baseline: the subjects' peak power output was measured and they underwent a baseline stochastic test followed immediately by a 5 km time trial (STI) and on a different day, a single 5 km time trial test (Tl) was undertaken. Study 1: In the following week the subjects repeated the stochastic test with 5 km time trial (ST2) and on a different day a 5 km time trial (T2). During T2 blood samples were taken at regular intervals as well as during recovery. A muscle biopsy was taken after T2 in the recovered state. The major performance predictors were the 5-km time trials (TTl and TT2) with a coefficient of variation between the thirteen trained male cyclists of 0.6%. The 5 km time trials in the fatigued state (STI and ST2) had a coefficient of variation of 0.7%. Results: There was a significant difference between 5 km TT performed fresh and 5km TT performed fatigued (P=0.0001). The decrement in time ranged between 1.0 sec to 38.0 sec. The relationship between two different high intensity endurance performance tests: PSPO and 5 km TT (TT mean) had a correlation ofr=-0.79 P<O.OI. The correlation between PSPO and the 5 km TT performed in the fatigued condition (ST mean) was r= -0.60 P<0.05. There was also a relationship between age and PSPO (F 0.73; P<0.05). Age showed a good negative relationship with TT mean (F- 0.71; P<0.05). Mass and PSPO were also correlated (FO.85; P<O.OI). Plasma lactate concentrations were significantly different from rest at all other time points P<O.OOOIup to 20 minutes post-exercise. Hypoxanthine (P<O.OOOI)and urate (P=O.05) concentrations were also significantly different from rest at all other time points. There was a significant change in plasma hypoxanthine concentrations over time (P<0.0001). There was a significant correlation between plasma lactate concentration at time 0 in recovery and % Myosin Heavy Chain (MHC) I (FO.59, P<0.05) and % MHC na (F -0.61, P<0.05). Area under the curve for hypoxanthine showed significant relationships of F -0.53 (P=O.05) and F 0.56 (P<0.05) respectively for %MHC I and %MHC ITa. Study 2 - Supplementation: following T2 the subjects received Cr or placebo powder containing sachets to be ingested 4 times daily for the next week with carbohydrate also provided. Post-supplementation testing: the subjects returned and conducted another variable fixedworkload test with 5 km time trial (ST3) as well as a single 5 km time trial (T3). They once again underwent the same blood sampling routine and had another muscle biopsy in the rested state. The average of ST1 and ST2 was used as the major measure for performance under fatigued conditions and TTmean. Results: there was a significant difference between 5 km TT performed fresh and 5 km TT performed fatigued (P=0.0001). Plasma lactate, hypoxanthine and urate samples were taken at the postloading 5 km time trial (TT3). The levels of these plasma metabolites were compared to the concentrations of those sampled at TT2 and between the creatine and placebo groups. The plasma hypoxanthine levels were significantly different from rest for both the creatine and placebo groups (P<0.0001). Plasma urate had significant change in concentrations over the time points (P<0.005). Another significant difference was found between the creatine and placebo groups for the pre-and post tests conducted (P<0.005). The creatine group showed a non-significant increase (7%) in mean total intramuscular creatine concentration. No significant differences were found in the mean values for total nucleotide concentration pre- and post loading in the creatine and placebo groups. Conclusions: The 5 km performance test resulted in high values for plasma lactate, hypoxanthine and urate, an indication of fatigue induced by this performance test. Oral creatine supplementation did not improve performance significantly in the variable fixedworkload protocol 5 km time trials or the individual 5-km time trials and had an effect on adenine nucleotide metabolism in both the variable fixed-workload protocol 5-km time trial and individual 5 km time trial performance tests. / AFRIKAANSE OPSOMMING: Die 5 km fietsry tyd toets (TT) verg hoëvolgehoue, spierkrag en wesenlike oksidatiewe en glikolitiese energie verskaffing. Die doelwitte van hierdie tesis was eerstens om 'n nuwe fietsergometer toets te ontwerp vir die voorspelling van kompetisie prestasie. Die toets was 'n veranderlike, voorafvasgestelde werkladingstoets (VVWT). Dit is vergelyk met 'n maksimale volgehoue kraguitsetingstoets (MVKT) en 'n 5 km TT. Daarna is bepaal ofkreatien supplementasie 'n effek sou hê op enige van hierdie oefeningstoetse of metabolisme tydens die 5 km TT. Die supplementasie eksperiment was 'n enkelblinde, plasebo-gekontroleerde studie ontwerp. Dertien manlike fietsryers het vrywilliglik deelgeneem. Resultate: Daar was 'n statisties betekenisvolle verskil tussen die 5 km TT wat vars onderneem is en die wat direk na die VVWT onderneem is (P=O.OOOl). Daar was ook 'n betekenisvolle korrelasie tussen die twee verskillende hoë intensiteit korttydsvak oefeningstoetse (r=-0.79 P<O.Ol vir TT en MVKT). Plasma laktaat konsentrasies was betekenisvol verhoog met vergelyking van die monsters geneem tydens rus en all ander onteledings tydspunte (P<0.0001) tot en met 20 minute na oefening. Hypoxantien (P<O.OOOl) en uraat (P=0.05) konsentrasies was ook betekenisvol verskillend van rus by alle ander tysdpunte. Daar was 'n betekenisvolle korrelasie tussen plasma laktaat direk na oefening en die % Myosien Swaarketting (MIlC) I (r=0.59, P<0.05) en % MHC ITa (r= - 0.61, P<0.05). Studie 2 - Na supplementasie was daar geen verskil in oefeningsprestasie nie maar wel in plasma metaboliet waardes van nie. Gevolgtrekkings: Die 5 km TT het baie hoë waardes vir plasma laktaat tot gevolg gehad, asook hypoxantien en uraat, 'n indikasie van die hoë mate van vermoeienis deur hierdie oefeningtoets berwerkstellig. Kreatine supplementasie kon nie oefeningsprestasie verbeter nie.

Live high - train low altitude camps can enhance endurance power at sea level by 1-2% (Levine & Stray-Gunderson, 1997). More convenient methods to simulate altitude exposure are now available, but their effects on performance are less well characterized. In this study, we investigated intermittent hypoxic training (IHT) using an Hypoxicator, a device that produces oxygen-depleted air that athletes breathe intermittently through masks in a small group at a central venue. Twelve highly-competitive, male cyclists and multi-sport athletes (IHT group) underwent IHT in two, four-week bouts separated by eight weeks. Bout one consisted of 20 one-hour exposures and bout two 18 exposures where normal and low-oxygenated air was breathed in alternating five-minute intervals. The percentage of oxygen inhaled by the subjects was adjusted to produce an oxygen saturation of the blood of 88-92% in the first week of the study, decreasing to 76-80% (equivalent to an altitude of approximately 6000m) in the final week. A control group of 13 similar athletes did not use the Hypoxicator. Performance trials and blood tests were at four-week intervals; there were 3 trials (familiarization and reliability) before use of the Hypoxicator, 3 trials after to determine the effect of simulated altitude, then a second four-week exposure and one more trial. The measures of performance were mean power in a 16-km time trial on a Kingcycle ergometer (IHT group only) and power in a lactate-threshold test at 3 mmol/L above baseline (both groups). The measures from the blood tests were haemoglobin and haematocrit. There was a gradual but erratic improvement in performance in the time trial and lactate threshold tests over the course of the study in both groups, indicating an improvement through training. Relative to the last baseline test (Trial 3), the IHT group showed a 0.6% decrease in mean power over and above the effect of training in the 16-km time trial in Trial 4, nine days after last use of IHT. There was a 0.3% increase in mean power independent of the training effect in Trial 7, after the second round of altitude exposure. Uncertainty in these changes in performance was ±3.5% (95% confidence interval). The changes in lactate threshold in trials 4 and 7 indicate a possible improvement as a result of IHT exposure. Uncertainty in these changes was ±4.0%. There were negligible changes in the haemoglobin and hematocrit of either group at any time. There was small evidence of high responders, who were probably subjects with the DD genotype for the angiotensin converting enzyme gene. The time exposed to IHT had no bearing on performance and there was no evidence "peak" in results at either four or eight weeks after exposure to IHT. In summary, four weeks of IHT exposure probably resulted in a trivial effect on 16-km time-trial performance and the effort-independent measures provided no further clear-cut evidence of a performance improvement.

Live high - train low altitude camps can enhance endurance power at sea level by 1-2% (Levine & Stray-Gunderson, 1997). More convenient methods to simulate altitude exposure are now available, but their effects on performance are less well characterized. In this study, we investigated intermittent hypoxic training (IHT) using an Hypoxicator, a device that produces oxygen-depleted air that athletes breathe intermittently through masks in a small group at a central venue. Twelve highly-competitive, male cyclists and multi-sport athletes (IHT group) underwent IHT in two, four-week bouts separated by eight weeks. Bout one consisted of 20 one-hour exposures and bout two 18 exposures where normal and low-oxygenated air was breathed in alternating five-minute intervals. The percentage of oxygen inhaled by the subjects was adjusted to produce an oxygen saturation of the blood of 88-92% in the first week of the study, decreasing to 76-80% (equivalent to an altitude of approximately 6000m) in the final week. A control group of 13 similar athletes did not use the Hypoxicator. Performance trials and blood tests were at four-week intervals; there were 3 trials (familiarization and reliability) before use of the Hypoxicator, 3 trials after to determine the effect of simulated altitude, then a second four-week exposure and one more trial. The measures of performance were mean power in a 16-km time trial on a Kingcycle ergometer (IHT group only) and power in a lactate-threshold test at 3 mmol/L above baseline (both groups). The measures from the blood tests were haemoglobin and haematocrit. There was a gradual but erratic improvement in performance in the time trial and lactate threshold tests over the course of the study in both groups, indicating an improvement through training. Relative to the last baseline test (Trial 3), the IHT group showed a 0.6% decrease in mean power over and above the effect of training in the 16-km time trial in Trial 4, nine days after last use of IHT. There was a 0.3% increase in mean power independent of the training effect in Trial 7, after the second round of altitude exposure. Uncertainty in these changes in performance was ±3.5% (95% confidence interval). The changes in lactate threshold in trials 4 and 7 indicate a possible improvement as a result of IHT exposure. Uncertainty in these changes was ±4.0%. There were negligible changes in the haemoglobin and hematocrit of either group at any time. There was small evidence of high responders, who were probably subjects with the DD genotype for the angiotensin converting enzyme gene. The time exposed to IHT had no bearing on performance and there was no evidence "peak" in results at either four or eight weeks after exposure to IHT. In summary, four weeks of IHT exposure probably resulted in a trivial effect on 16-km time-trial performance and the effort-independent measures provided no further clear-cut evidence of a performance improvement.

The development of noncircular chainrings to improve cycling performance has been in progress since the 1980’s and continues apace. The aim of this study was to compare performance time and physiological responses in cycling using a standard circular chainring versus a noncircular chainring developed in 2005: the Rotor Q-Ring. Eight competitive male cyclists were pre-tested using the original circular chainrings and also on the initial week of testing. The intervention consisted of cycling with Rotor Q-Rings for four weeks. Post-testing occurred with the original chainrings for the final week of testing. Testing consisted of a maximal or submaximal graded exercise test followed by a 1 k time trial. Oxygen consumption, carbon dioxide output, heart rate, ventilation, respiratory exchange ratio, and perceived exertion were continuously measured during the tests. Blood lactate concentration was measured during the last 30 s of each three minute stage. Five minutes after the submaximal test, participants performed an “all out” 1 k trial for time as well as maximum and average power. The main findings were: 1) Participants were on average 1.6 seconds faster in the 1 k time trial with Rotor Q-Rings compared to a circular chainrings. 2) There was a significant increase in average power (26.7 watts) and average speed (0.7 kph) during the 1 k time trial with Rotor Q-Rings. 3) Oxygen consumption (during weeks 2-4) and heart rate (weeks 1-3) were significantly lower with Rotor Q-Rings during submaximal testing when compared to circular chainrings. However, in contrast to our hypotheses no benefits were observed for other submaximal dependent measures (i.e., CO2, VE, RER, RPE, GE, DE, and lactate).

The 2 in VO2 is in subscript. / Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Please see fulltext for abstract / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming

Dissertation submitted in partial compliance with the requirements for the Masters’ Degree in Technology: Chiropractic, Durban University of Technology, 2013. / Background : Core strengthening may improve athletic ability by providing stability to the trunk, and as a result, stabilising the pelvis. The leverage from which cyclists generate power may be enhanced as a result of a stable pelvis, thereby improving the cyclist’s performance. In the popular, highly competitive sport of cycling, performance enhancement is much sought after. Despite its widespread use, research involving core strengthening in sporting situations is lacking, with studies investigating the effect of a core strengthening programme on cycling performance yet to be investigated. Objectives : To determine the participants’ cycling speed, power, cadence and completion time, and core strength in terms of objective findings, pre- and post- core strengthening intervention, in the whole sample and within the two age strata. To determine the participants’ heart rate in terms of objective findings, and the rate of perceived exertion in terms of subjective findings, pre- and post- core strengthening intervention, in the whole sample and within the two age strata. To determine the participants’ perception of change in speed, power and cadence post- intervention, in the whole sample and within the two age strata. Method : Forty-two asymptomatic cyclists performed two 1.5 km time trials, pre- and post- core strengthening intervention. Core strength assessments were performed pre- and post- intervention, using the Pressure Biofeedback Unit, and the maximum and average speed (km/hr), power (w) and cadence (rpm), and completion time (s) were recorded pre- and post- intervention, using the Computerised Electromagnetic Roller resistance Ergometer (Tacx Trainer). Heart rate and rate of perceived exertion (RPE) were recorded pre- and post- intervention, as well as the participant’s perception of change in speed, power, and cadence post- intervention. SPSS version 20 (SPSS Inc) was used to analyse the data, in the whole sample and stratified into two age strata. Results : ll cycling performance indicators, speed, power, cadence and completion time showed a significant improvement post- intervention, in the whole sample, and within the two age strata. Core strength indicators showed a significant improvement post- intervention, in the whole sample and within the two age strata. A significant decrease in rate of perceived exertion and corresponding heart rate measurements post- intervention was observed in the whole sample. Similarly, the younger age strata reflected a significant decrease in rate of perceived exertion, however heart rate measurements were not significant. In contrast, the older age strata showed significant changes in heart rate measurements, with no significance in rate of perceived exertion measurements. The majority of participants experienced an increased perception in all outcomes post- intervention. Conclusions: The results of this study found that core strengthening had a statistically significant effect (p < 0.001) on cycling performance, both in terms of objective and subjective findings. Future studies could address the effect of core strengthening in an endurance setting.

No description available.

Pseudoephedrine is a mild stimulant which partially mimics the action of noradrenaline and adrenaline. Recently, pseudoephedrine has been removed from the World Anti Doping Agency (WADA) prohibited substances list. This occurred despite limited research in regards to its effects on sporting performance, and no studies on prolonged exercise performance (>2hrs). There is some evidence to suggest pseudoephedrine may have an ergogenic effect at dosages exceeding therapeutic levels, possibly by masking fatigue. This study investigated the possible ergogenic effects of pseudoephedrine on endurance cycling performance. Using a double blind, randomised cross over design, eight well-trained cyclists (VO2max 69 ± 2 ml×kg-1) performed two self- paced performance time trials at least 6 days apart. Ninety minutes prior to the trial, subjects consumed either placebo or pseudoephedrine (2.5 mg×kg-1) capsules. Diet and exercise were controlled for 48 hrs prior to each trial. The time trial required completion of a set amount of work, equivalent to riding at two and half hours at a power output calculated to elicit 70% VO2 max. Power output was measured using a Powertap system (Cycle Ops Power, Saris Cycling Group, USA). Venous blood samples were collected prior to capsule ingestion, just before starting the trial, and at every 20% increment in completed work until completion and were analysed for glucose and lactate. Heart rate was recorded throughout the trial. There was no significant effect of pseudoephedrine on average performance (p=0.235). Heart rate was significantly higher with pseudoephedrine consumption compared to placebo (p<0.05), but there was no significant difference in glucose or lactate between trials. Pseudoephedrine does not significantly improve self-paced endurance cycling performance, though the individual response was variable. However, exercising heart rate was significantly higher during exercise after ingestion of the stimulant.

Background: Pseudoephedrine (PSE) is a mild central nervous system stimulant that when consumed at a high dosage has the potential to alter physiological and psychophysical responses. PSE is widely accessible as over-the-counter medication and despite limited research into PSE at high dosages or its effects on prolonged exercise (>2 hours) is no-longer on the World Anti-Doping Association’s banned substance list. Currently unrestricted in sport and with no real understanding of the abovementioned responses during endurance exercise there is a high potential for abuse in sport. A recent study performed in our laboratory found PSE to improve self-paced cycling performance in some individuals, however no physiological measurements were taken Purpose: The primary purpose of this study was to determine the physiological effects of PSE at a dosage previously shown to improve performance (2.5 mg/kg) in some individuals during prolonged cycling. A secondary purpose of this study was to assess the effect on endurance cycling performance. Methods: In a randomized, double-blind and counter-balanced design, ten welltrained cyclists participated in two trials, consisting of 120 min of fixed-intensity cycling at 65% VO2max followed by a set work, self-paced time-trial (TT) of ~30 min, following ingestion of either 2.5 mg/kg PSE or visual-matched glucose placebo. Venous blood samples were collected before and during exercise, along with body temperatures and heart rate. Perceived effort and expired gas samples were collected during exercise. Exercise and diet was controlled ~48-hours prior to the trials. Results: Mean heart rate was significantly higher with PSE (P = 0.028) during fixed-intensity exercise. Blood glucose concentrations were significantly lower with PSE (P <0.001) for the first 40 min of fixed-intensity exercise. Respiratory exchange ratio was lower in the final 20-min of fixed-intensity and TT with PSE. Blood lactate, perceived effort, ventilation, and body temperatures were not significantly different between conditions during exercise, nor was TT performance; however individual response was variable. Conclusions: PSE ingestion increased heart rate during endurance cycling and initially suppressed carbohydrate release into the bloodstream while increasing fat oxidation in the later stages of exercise. Despite individual responses, endurance cycling performance remained unchanged with PSE ingestion.

Background: Pseudoephedrine (PSE) is a mild central nervous system stimulant that when consumed at a high dosage has the potential to alter physiological and psychophysical responses. PSE is widely accessible as over-the-counter medication and despite limited research into PSE at high dosages or its effects on prolonged exercise (>2 hours) is no-longer on the World Anti-Doping Association’s banned substance list. Currently unrestricted in sport and with no real understanding of the abovementioned responses during endurance exercise there is a high potential for abuse in sport. A recent study performed in our laboratory found PSE to improve self-paced cycling performance in some individuals, however no physiological measurements were taken Purpose: The primary purpose of this study was to determine the physiological effects of PSE at a dosage previously shown to improve performance (2.5 mg/kg) in some individuals during prolonged cycling. A secondary purpose of this study was to assess the effect on endurance cycling performance. Methods: In a randomized, double-blind and counter-balanced design, ten welltrained cyclists participated in two trials, consisting of 120 min of fixed-intensity cycling at 65% VO2max followed by a set work, self-paced time-trial (TT) of ~30 min, following ingestion of either 2.5 mg/kg PSE or visual-matched glucose placebo. Venous blood samples were collected before and during exercise, along with body temperatures and heart rate. Perceived effort and expired gas samples were collected during exercise. Exercise and diet was controlled ~48-hours prior to the trials. Results: Mean heart rate was significantly higher with PSE (P = 0.028) during fixed-intensity exercise. Blood glucose concentrations were significantly lower with PSE (P <0.001) for the first 40 min of fixed-intensity exercise. Respiratory exchange ratio was lower in the final 20-min of fixed-intensity and TT with PSE. Blood lactate, perceived effort, ventilation, and body temperatures were not significantly different between conditions during exercise, nor was TT performance; however individual response was variable. Conclusions: PSE ingestion increased heart rate during endurance cycling and initially suppressed carbohydrate release into the bloodstream while increasing fat oxidation in the later stages of exercise. Despite individual responses, endurance cycling performance remained unchanged with PSE ingestion.