Trained male cyclists (6 in study 1, 5 in study 2) cycled to exhaustion (EXH) at 75% of VO₂ max twice; once in the non-supplemented (NS) state and once in the vitamin B-6 (B-6)(20 mg PN) supplemented (S) state. The diet contained 2.3 mg B-6 in study 1 and 1.9 mg B-6 in study 2. Urine was collected during each dietary period. During each exercise (EX) test, blood was drawn prior to (PRE), one hour during (DX), immediately after (POST) and one hour after (POST 60) EX and sweat was collected. Compared to baseline (PRE) levels, plasma pyridoxal 5'-phosphate (PLP) and vitamin B-6 (PB-6) concentrations increased at DX, decreased at POST, and decreased below PRE at POST 60 in the NS and S states. EX to EXH in the S state resulted in a greater increase in PLP DX in study 1 (31% increase vs. 16%) and PB-6 in study 2 (25% increase vs. 11%) as compared to the NS state. Red blood cell (RBC) PLP significantly increased from POST to POST 60 in the S state in study 2. The excretion of urinary 4-pyridoxic acid (4-PA) and urinary B-6 (UB-6) was not significantly altered by EX to EXH. The mean excretion of 4-PA was significantly greater in the NS state in study 2 (7.98 ±1.83 mmol/d) as compared to the excretion in study 1 (6.20 ±0.93 mmol/d), whereas the excretion was significantly greater in the S state in study 1 (92.2 ±8.69 mmol/d) compared to the excretion in study 2 (82.7 ±6.16 mmol/d). The percent of B-6 intake excreted as UB-6 (6% in study 1 and 10% in study 2) was significantly different between the studies in the NS state. Vitamin B-6 supplementation did not significantly alter the rise in growth hormone (hGH) concentration seen with EX to EXH. The loss of B-6 in sweat with EX to EXH was not altered by B-6 supplementation. The loss of B-6 in sweat ranged from 0.0011 mmol to 0.0039 mmol. Therefore, EX to EXH in the B-6 S state resulted in a greater increase in plasma PLP and PB-6 DX as compared to the NS state. The decrease in PB-6 and PLP at POST 60 in the S state coincided with a significant increase in RBC PLP, suggesting the movement of B-6 from the plasma into the RBC at POST 60. EX to EXH and B-6 supplementation did not alter the excretion of 4-PA or UB-6 suggesting that B-6 metabolism was unchanged. The loss of B-6 in sweat was comparable to previously reported values and was not altered by B-6 supplementation. B-6 supplementation did not alter the changes in hGH resulting from EX to EXH alone. / Graduation date: 1995

The purpose of this study was to determine if barbell circuit training (RTC) as a model for concurrent training is superior to high intensity interval (CTHI) or moderate intensity continuous (CTMI) cycling for changes in muscular strength, hypertrophy, and body composition. Eleven trained males were recruited and counterbalanced into three groups. Each program featured three alternating days of resistance training per week, with one of the above time-equated (30-minute) concurrent training modalities between sessions. All groups increased muscular strength (p<0.05, RTC=7.48%, CTHI=10.32%, CTMI=15.74%) with no group differences (p>0.05). Increases in upper body muscle hypertrophy were similar in RTC and CTMI (p<0.01, RTC=20.18%, CTMI=20.97%), increases in lower body muscle hypertrophy only occurred in CTMI (VM: p=0.01, 38.59%, VLP: p=0.07, 13.33%), while no hypertrophy changes were detected in CTHI (p>0.05), no group experienced changes in body composition (p>0.05). These findings suggest similar muscle performance benefits from barbell circuit or cycling concurrent training. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015 / FAU Electronic Theses and Dissertations Collection

Seven experienced male bicyclists performed four endurance test rides at 70% ( ± 5) VO₂ max on a bicycle at 90 RPM over a four week period. stationary Subjects consumed a high carbohydrate diet (70%) for two days prior to each test ride. During each test, heart rate (HR), rate of perceived exertion (RPE), VO₂ , respiratory exchange ratio (R), serum free fatty acid (FFA) and serum glucose levels were measured. One of the four test treatments was randomly administered, in a single-blind design, at 5, 25, and 40 minutes into each exercise bout. The control trial (CTR) included 50 gelatin capsules containing water, and a lemonade beverage (150 ml each) sweetened with an artificial sweetener (Saccharin). The test mixtures were made up in the same manner as the control with the addition of one of the test substances: 1) MCT oil (M), 2) glucose polymer (P) (Polycose, Ross Laboratories), 3) MCT plus glucose polymer (MP). Depending on the treatment used, MCT oil-containing capsules replaced water-capsules and/or Polycose was dissolved in the lemonade beverage. Total caloric intake of each trial, except control, was 360 calories. No significant difference was found between mean time to exhaustion for the four treatments. No significant difference was noted between treatments for R, VO₂ , and HR responses (p < 0.05). Significantly greater RPE values were found over the first 60 minutes of exercise for the Control treatment as compared to the other three treatments (p < 0.05). Repeated measures ANOVA showed that significantly higher serum glucose values existed for treatment P as compared to M and also significantly higher serum FFA values existed for treatment M as compared to both P and MCT oil with Polycose (MP) over the first 60 minutes of exercise (p < 0.05). Although the combination of MCT oil and Polycose would theoretically enhance endurance performance due to an increased supply of both FFA and glucose available for muscular metabolism, this dietary treatment was ineffective in prolonging exercise time. / Master of Science

A dose response relationship between carbohydrate (CHO) ingestion and exercise performance has not been consistently reported. Additionally the underlying metabolic and neuromuscular explanations for an improvement in performance with increasing doses of CHO have not been fully explained. In Chapter 2 of this thesis 20 male cyclists completed 2 h of submaximal exercise followed by a time trial task (531 ± 48KJ). Three CHO electrolyte beverages, plus a control (water), were administered during a 2 h ride providing 0, 20, 39 or 64 g CHO·h-1 at a fluid intake rate of 1 L·h-1. Performance was assessed by time to complete the time trial task, mean power output sustained, and pacing strategy used. Mean task completion time (min:sec ± SD) for 39 g·h-1 (34:19.5 ± 03:07.1, p=0.006) and 64 g·h-1 (34:11.3 ± 03:08.5 p=0.004) of CHO were significantly faster than control (37:01.9 ± 05:35.0). The mean percentage improvement from control was -6.1% (95% CI: -11.3 to -1.0) and -6.5% (95% CI: -11.7 to -1.4) in the 39 and 64 g·h-1 trials respectively. The 20 g·h-1 (35:17.6 ± 04:16.3) treatment did not reach statistical significance compared to control (p = 0.126) despite a mean improvement of -3.7% (95% CI -8.8 to 1.5%). These data demonstrate that consuming CHO at a rate between 39 to 64 g·h-1 is likely to be optimal for most individuals looking to utilise a single source CHO as an ergogenic aid during endurance performances lasting less than 3 hrs. Attempts have been made to try and understand the acute metabolic regulation that occurs when ingesting increasing amounts of CHO. However, no one study has fully investigated the metabolic mechanisms underlying graded increments of CHO ingestion. In Chapter 3 we aimed to utilise stable isotopes and blood metabolite profiles to examine the integrated physiological responses to CHO ingestion when ingested at rates throughout the range where performance gains appear greatest. Twenty well-trained male cyclists completed 2 h constant load ride (95% lactate threshold, 185 ± 25W) where one of three CHO beverages, or a control (water), were administered every 15 min, providing participants with 0, 20, 39 or 64 g CHO·h-1 at a fixed fluid intake rate of 1L·h-1. Dual glucose tracer techniques (6,6,2H2 glucose and U13C labelled glucose) were used to determine glucose kinetics and exogenous carbohydrate oxidation (EXO) during exercise. Endogenous CHO contribution was suppressed in the second hour of exercise when consuming 39 and 64 g·h-1 in comparison to 0 g·h-1 (-7.3%, 95%CI: -13.1 to -1.6 and -11.2%, 95%CI: -16.9 to -5.5 respectively). Additionally, consuming 64 g·h-1 suppressed the endogenous CHO contribution by -7.2% (95%CI: -1.5 to -13.0) compared to the 20 g·h-1 treatment. Exogenous CHO oxidation rate increased by 0.13 g·min-1 (95%CI: 0.10 to 0.15) and 0.29 g·min-1 (95%CI: 0.27 to 0.31) when consuming 39 and 64 g·h-1 in comparison to 20 g·h-1 of CHO. Peak exogenous CHO oxidation rates were 0.34 (0.06), 0.54 (0.09) and 0.78 (0.19) g·min-1 for 20, 39 and 64 g·h-1 respectively. Plasma NEFA concentration was 0.10 (95%CI: 0.07 to 0.13), 0.12 (95%CI: 0.10 to 0.16) and 0.16 (95%CI: 0.13 to 0.19) mmol.L-1 higher when consuming 0 g·h-1 in comparison to 20, 39 and 64 g·h-1 respectively. Both 39 and 64 g·h-1 were effective at sparing endogenous CHO stores of which it is estimated that most of this is liver glycogen sparing, but the measured response was highly variable between individuals. Consuming 39 g·h-1 of CHO appears to be the minimum ingestion rate required to have a significant metabolic effect that results in an increase in performance. Recent research has indicated a key role of endogenous CHO sensing and oral glucose sensing in maintaining central drive and peripheral function during endurance exercise tasks. Consuming 39 and 64 g·h-1 of CHO elicits the greatest improvements in performance and also demonstrate a similar metabolic response. The improvement in subsequent time trial performance when consuming 39 and 64 g·h-1 coincided with significant alterations in whole body substrate usage that lead to endogenous CHO sparing at the same ingestion rates. In Chapter 4 we aimed to utilise gold standard neuromuscular function assessment techniques, alongside novel measures, to investigate the effect of consuming different rates of CHO on neuromuscular function during and following prolonged cycling exercise. In a double-blind, randomised cross-over design, well-trained male cyclists (n=20, mean±SD, age 34 ± 10 y, mass 75.8 ± 9 kg, peak power output 394 ± 36 W, V̇O2max 62 ± 9 ml·kg-1·min-1) completed 2 familiarisation trials then 4 experimental trials. Trials involved a 2 h submaximal ride followed by a high intensity time trial task lasting approx. 35 min with each of 0, 20, 39 and 64 g·h-1 CHO ingestion rates during submaximal exercise. Each trial involved pre and post exercise assessments (MVC, Mwave twitch potentiation and force, motor unit recruitment and firing rate assessment using high density EMG) and during exercise (gross EMG amplitude). MVC peak torque values were reduced post exercise by -20.4 nM (95%CI: -26.5 to -14.4) in comparison to pre value on all trials with no differences between trials. The firing rates of early recruited motor units significantly increased by 1.55 pps (95%CI: 0.51 to 2.59) following exercise in comparison to pre-exercise rates. Gross EMG during the 2 h cycling bout revealed a main effect of treatment (p<0.01) but post hoc comparisons provided no clarity and likely reflect methodological issues. Consuming CHO at ingestion rates between 20 and 64 g·h-1 had little to no impact on the neuromuscular function of well-trained cyclists when comparing pre and post fatiguing exercise values. Despite differences in time trial completion time between trials, following exercise to fatigue in an endurance task, no post exercise differences were detected.

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.