Effect of fat adaptation and carbohydrate restoration on metabolism and performance during prolonged cycling

2000 ◽  
Vol 89 (6) ◽  
pp. 2413-2421 ◽  
Author(s):  
Louise M. Burke ◽  
Damien J. Angus ◽  
Gregory R. Cox ◽  
Nicola K. Cummings ◽  
Mark A. Febbraio ◽  
...  
Keyword(s):  
Muscle Glycogen ◽  
High Fat Diet ◽  
Performance Testing ◽  
Time Trial ◽  
Random Order ◽  
Cycling Performance ◽  
High Fat ◽  
Glycogen Utilization ◽  
And Performance ◽  
Glycogen Sparing

For 5 days, eight well-trained cyclists consumed a random order of a high-carbohydrate (CHO) diet (9.6 g · kg−1 · day−1 CHO, 0.7 g · kg−1 · day−1 fat; HCHO) or an isoenergetic high-fat diet (2.4 g · kg−1 · day−1 CHO, 4 g · kg−1 · day−1 fat; Fat-adapt) while undertaking supervised training. On day 6,subjects ingested high CHO and rested before performance testing on day 7 [2 h cycling at 70% maximal O2consumption (SS) + 7 kJ/kg time trial (TT)]. With Fat-adapt, 5 days of high-fat diet reduced respiratory exchange ratio (RER) during cycling at 70% maximal O2 consumption; this was partially restored by 1 day of high CHO [0.90 ± 0.01 vs. 0.82 ± 0.01 ( P < 0.05) vs. 0.87 ± 0.01 ( P < 0.05), for day 1, day 6, and day 7, respectively]. Corresponding RER values on HCHO trial were [0.91 ± 0.01 vs. 0.88 ± 0.01 ( P < 0.05) vs. 0.93 ± 0.01 ( P < 0.05)]. During SS, estimated fat oxidation increased [94 ± 6 vs. 61 ± 5 g ( P < 0.05)], whereas CHO oxidation decreased [271 ± 16 vs. 342 ± 14 g ( P < 0.05)] for Fat-adapt compared with HCHO. Tracer-derived estimates of plasma glucose uptake revealed no differences between treatments, suggesting muscle glycogen sparing accounted for reduced CHO oxidation. Direct assessment of muscle glycogen utilization showed a similar order of sparing (260 ± 26 vs. 360 ± 43 mmol/kg dry wt; P = 0.06). TT performance was 30.73 ± 1.12 vs. 34.17 ± 2.48 min for Fat-adapt and HCHO ( P = 0.21). These data show significant metabolic adaptations with a brief period of high-fat intake, which persist even after restoration of CHO availability. However, there was no evidence of a clear benefit of fat adaptation to cycling performance.

High-Fat Diet versus Habitual Diet Prior to Carbohydrate Loading: Effects on Exercise Metabolism and Cycling Performance

2001 ◽  
Vol 11 (2) ◽  
pp. 209-225 ◽  
Author(s):  
Estelle V. Lambert ◽  
Julia H. Goedecke ◽  
Charl van Zyl ◽  
Kim Murphy ◽  
John A. Hawley ◽  
...  
Keyword(s):  
Muscle Glycogen ◽  
High Fat Diet ◽  
Time Trial ◽  
Cycling Performance ◽  
Peak Oxygen Uptake ◽  
High Fat ◽  
Lactate Oxidation ◽  
Cycling Time Trial ◽  
Habitual Diet ◽  
Loading Effects

We examined the effects of a high-fat diet (HFD-CHO) versus a habitual diet, prior to carbohydrate (CHO)-loading on fuel metabolism and cycling time-trial (TT) performance. Five endurance-trained cyclists participated in two 14-day randomized cross-over trials during which subjects consumed either a HFD (>65% MJ from fat) or their habitual diet (CTL) (30 ± 5% MJ from fat) for 10 day, before ingesting a high-CHO diet (CHO-loading, CHO > 70% MJ) for 3 days. Trials consisted of a 150-min cycle at 70% of peak oxygen uptake (V̇O2peak), followed immediately by a 20-km TT. One hour before each trial, cyclists ingested 400 ml of a 3.44% medium-chain triacylglycerol (MCT) solution, and during the trial, ingested 600 ml/hour of a 10% 14C-glucose + 3.44% MCT solution. The dietary treatments did not alter the subjects’ weight, body fat, or lipid profile. There were also no changes in circulating glucose, lactate, free fatty acid (FFA), and β-hydroxybutyrate concentrations during exercise. However, mean serum glycerol concentrations were significantly higher (p < .01) in the HFD-CHO trial. The HFD-CHO diet increased total fat oxidation and reduced total CHO oxidation but did not alter plasma glucose oxidation during exercise. By contrast, the estimated rates of muscle glycogen and lactate oxidation were lower after the HFD-CHO diet. The HFD-CHO treatment was also associated with improved TT times (29.5 ± 2.9 min vs. 30.9 ± 3.4 min for HFD-CHO and CTL-CHO, p < .05). High-fat feeding for 10 days prior to CHO-loading was associated with an increased reliance on fat, a decreased reliance on muscle glycogen, and improved time trial performance after prolonged exercise.

The Effects of Carbohydrate Loading on Muscle Glycogen Content and Cycling Performance

1995 ◽  
Vol 5 (1) ◽  
pp. 25-36 ◽  
Author(s):  
Laurie H.G. Rauch ◽  
Ian Rodger ◽  
Gary R. Wilson ◽  
Judy D. Belonje ◽  
Steven C. Dennis ◽  
...  
Keyword(s):  
Body Mass ◽  
Muscle Glycogen ◽  
Power Output ◽  
Glycogen Content ◽  
Potato Starch ◽  
Random Order ◽  
Cycling Performance ◽  
Muscle Glycogen Content ◽  
Glycogen Utilization ◽  
And Performance

This study compared the effects of supplementing the normal diets of 8 endurance-trained cyclists with additional carbohydrate (CHO), in the form of potato starch, for 3 days on muscle glycogen utilization and performance during a 3-hr cycle ride. On two occasions prior to the trial, the subjects ingested in random order either their normal CHO intake of 6.15 ± 0.23 g/kg body mass/day or a high-CHO diet of 10.52 ± 0.57 g/kg body mass/day. The trial consisted of 2 hr of cycling at ~75% ofwith five 60-s sprints at 100%at 20-min intervals, followed by a 60-min performance ride. Increasing CHO intake by 72 ± 9% for 3 days prior to the trial elevated preexercise muscle glycogen contents, improved power output, and extended the distance covered in 1 hr. Muscle glycogen contents were similar at the end of the 3-hr trial, indicating a greater utilization of glycogen when subjects were CHO loaded, which may have been responsible for their improved cycling performance.

scholarly journals Effects of fat adaptation and carbohydrate restoration on prolonged endurance exercise

2001 ◽  
Vol 91 (1) ◽  
pp. 115-122 ◽  
Author(s):  
Andrew L. Carey ◽  
Heidi M. Staudacher ◽  
Nicola K. Cummings ◽  
Nigel K. Stepto ◽  
Vasilis Nikolopoulos ◽  
...  
Keyword(s):  
Endurance Exercise ◽  
Power Output ◽  
High Fat Diet ◽  
Respiratory Exchange Ratio ◽  
Time Trial ◽  
Fat Oxidation ◽  
Significant Benefit ◽  
High Fat ◽  
Competitive Athletes ◽  
And Performance

We determined the effect of fat adaptation on metabolism and performance during 5 h of cycling in seven competitive athletes who consumed a standard carbohydrate (CHO) diet for 1 day and then either a high-CHO diet (11 g · kg−1 · day−1 CHO, 1 g · kg−1 · day−1 fat; HCHO) or an isoenergetic high-fat diet (2.6 g · kg−1 · day−1 CHO, 4.6 g · kg−1 · day−1 fat; fat-adapt) for 6 days. On day 8, subjects consumed a high-CHO diet and rested. On day 9, subjects consumed a preexercise meal and then cycled for 4 h at 65% peak O2 uptake, followed by a 1-h time trial (TT). Compared with baseline, 6 days of fat-adapt reduced respiratory exchange ratio (RER) with cycling at 65% peak O2 uptake [0.78 ± 0.01 (SE) vs. 0.85 ± 0.02; P < 0.05]. However, RER was restored by 1 day of high-CHO diet, preexercise meal, and CHO ingestion (0.88 ± 0.01; P < 0.05). RER was higher after HCHO than fat-adapt (0.85 ± 0.01, 0.89 ± 0.01, and 0.93 ± 0.01 for days 2, 8, and 9, respectively; P < 0.05). Fat oxidation during the 4-h ride was greater (171 ± 32 vs. 119 ± 38 g; P < 0.05) and CHO oxidation lower (597 ± 41 vs. 719 ± 46 g; P < 0.05) after fat-adapt. Power output was 11% higher during the TT after fat-adapt than after HCHO (312 ± 15 vs. 279 ± 20 W; P = 0.11). In conclusion, compared with a high-CHO diet, fat oxidation during exercise increased after fat-adapt and remained elevated above baseline even after 1 day of a high-CHO diet and increased CHO availability. However, this study failed to detect a significant benefit of fat adaptation to performance of a 1-h TT undertaken after 4 h of cycling.

Cycling Performance and Training Load: Effects of Intensity and Duration

2020 ◽  
pp. 1-9 ◽  
Author(s):  
Antonis Kesisoglou ◽  
Andrea Nicolò ◽  
Louis Passfield
Keyword(s):  
Exercise Intensity ◽  
Average Power ◽  
Time Trial ◽  
Exercise Bout ◽  
Random Order ◽  
Cycling Performance ◽  
Training Load ◽  
Subsequent Performance ◽  
Load Effects ◽  
Work Done

Purpose: To examine the effect of cycling exercise intensity and duration on subsequent performance and to compare the resulting acute performance decrement (APD) with total work done (TWD) and corresponding training-load (TL) metrics. Methods: A total of 14 male cyclists performed a 5-minute time trial (TT) as a baseline and after 4 initial exercise bouts of varying exercise intensity and duration. The initial exercise bouts were performed in a random order and consisted of a 5- and a 20-minute TT and a 20- and a 40-minute submaximal ride. The resulting APD was calculated as the percentage change in 5-minute TT from baseline, and this was compared with the TWD and TL metrics for the corresponding initial exercise bout. Results: Average power output was different for each of the 4 initial exercise bouts (; P < .001), and all bouts resulted in an APD. But APD was only different when comparing maximal with submaximal bouts (; P < .001). The APD contradicted TWD and TL metrics and was not different when comparing 5- and 20-minute maximal TTs or the 20- and 40-minute submaximal bouts. In contrast, TL metrics were different for all training sessions (; P < .001). Conclusion: An APD is found after initial exercise bouts consisting of 5- and 20-minute TTs and after 20- and 40-minute of submaximal exercise that is not consistent with the corresponding values for TWD or TL. This discrepancy highlights important shortcomings when using TWD and TL to compare exercise bouts of different intensity and duration.

Cycling Efficiency and Performance Following Short-Term Training Using Uncoupled Cranks

2009 ◽  
Vol 4 (1) ◽  
pp. 18-28 ◽  
Author(s):  
Andrew D. Williams ◽  
Isaac Selva Raj ◽  
Kristie L. Stucas ◽  
James W. Fell ◽  
Diana Dickenson ◽  
...  
Keyword(s):  
Lactate Threshold ◽  
Performance Enhancement ◽  
Average Power ◽  
Time Trial ◽  
Mechanical Efficiency ◽  
Cycling Performance ◽  
Peak Power Output ◽  
Gross Efficiency ◽  
And Performance ◽  
Study Participants

Objectives:Uncoupled cycling cranks are designed to remove the ability of one leg to assist the other during the cycling action. It has been suggested that training with this type of crank can increase mechanical efficiency. However, whether these improvements can confer performance enhancement in already well-trained cyclists has not been reported.Method:Fourteen well-trained cyclists (13 males, 1 female; 32.4 ± 8.8 y; 74.5 ± 10.3 kg; Vo2max 60.6 ± 5.5 mL·kg−1·min−1; mean ± SD) participated in this study. Participants were randomized to training on a stationary bicycle using either an uncoupled (n = 7) or traditional crank (n = 7) system. Training involved 1-h sessions, 3 days per week for 6 weeks, and at a heart rate equivalent to 70% of peak power output (PPO) substituted into the training schedule in place of other training. Vo2max, lactate threshold, gross efficiency, and cycling performance were measured before and following the training intervention. Pre- and post testing was conducted using traditional cranks.Results:No differences were observed between the groups for changes in Vo2max, lactate threshold, gross efficiency, or average power maintained during a 30-minute time trial.Conclusion:Our results indicate that 6 weeks (18 sessions) of training using an uncoupled crank system does not result in changes in any physiological or performance measures in well-trained cyclists.

scholarly journals Effect of altering substrate availability on metabolism and performance during intense exercise

2000 ◽  
Vol 84 (6) ◽  
pp. 829-838 ◽  
Author(s):  
John A. Hawley ◽  
Louise M. Burke ◽  
Damien J. Angus ◽  
Kieran E. Fallon ◽  
David T. Martin ◽  
...  
Keyword(s):  
Saturated Fat ◽  
Time Trial ◽  
Random Order ◽  
Plasma Free Fatty Acid ◽  
Fat Oxidation ◽  
Carbohydrate Oxidation ◽  
Substrate Selection ◽  
Substrate Availability ◽  
Intense Exercise ◽  
And Performance

The purpose of this study was to determine the effect of altering substrate availability on metabolism and performance during intense cycling. Seven highly trained men ingested a random order of three isoenergetic meals 90 min before cycling at 80 % maximal oxygen uptake (VO2max) for 20 min (about 310 W), followed by a 600 kJ time trial lasting about 30 min. Meals consisted of either 1·2 g saturated fat/kg body mass (BM) with 3500 U heparin intravenously (HIFAT) to elevate circulating plasma free fatty acid (FA) concentration, 2·5 g carbohydrate/kg BM (CHO) to elevate plasma glucose and insulin concentrations or 2·5 g carbohydrate+20 mg nicotinic acid/kg BM (NA) to suppress lipolysis and reduce free FA concentration. HIFAT elevated free FA concentration (HIFAT 1·3 (SEM 0·2), CHO 0·2 (sem 0·1), NA 0·1 (sem 0·1) mm; P<0·001), lowered the RER (HIFAT 0·94 (sem 0·01), CHO 0·97 (sem 0·01), NA 0·98 (sem 0·01); P<0·01) and increased the rate of fat oxidation (HIFAT 24 (sem 3), CHO 12 (sem 2), NA 8 (sem 3) μmol/kg per min; P<0·01) during the 20 min ride. Marked differences in fat availability and fuel utilisation, however, had little effect on performance in the subsequent time trial (HIFAT 320 (sem 16), CHO 324 (sem 15), NA 315 (sem 13) W). We conclude: (1) increased fat availability during intense cycling increases the rate of fat oxidation; but (2) the reduction in the rate of carbohydrate oxidation in the presence of high circulating plasma free FA is unlikely to enhance intense exercise performance lasting about 1 h; (3) substrate selection during intense (about 80 % VO2max) exercise is dominated by carbohydrate oxidation.

Reliability of Physiological Attributes and Their Association With Stochastic Cycling Performance

2014 ◽  
Vol 9 (2) ◽  
pp. 309-315 ◽  
Author(s):  
Gregory T. Levin ◽  
Paul B. Laursen ◽  
Chris R. Abbiss
Keyword(s):  
Power Output ◽  
Ventilatory Threshold ◽  
Intraclass Correlation ◽  
Time Trial ◽  
Cycling Performance ◽  
Peak Power Output ◽  
Cycling Time Trial ◽  
Physiological Variables ◽  
Physiological Attributes ◽  
And Performance

Purpose:To assess the reliability of a 5-min-stage graded exercise test (GXT) and determine the association between physiological attributes and performance over stochastic cycling trials of varying distance.Methods:Twenty-eight well-trained male cyclists performed 2 GXTs and either a 30-km (n = 17) or a 100-km stochastic cycling time trial (n = 9). Stochastic cycling trials included periods of high-intensity efforts for durations of 250 m, 1 km, or 4 km depending on the test being performing.Results:Maximal physiological attributes were found to be extremely reliable (maximal oxygen uptake [VO2max]: coefficient of variation [CV] 3.0%, intraclass correlation coefficient [ICC] .911; peak power output [PPO]: CV 3.0%, ICC .913), but a greater variability was found in ventilatory thresholds and economy. All physiological variables measured during the GXT, except economy at 200 W, were correlated with 30-km cycling performance. Power output during the 250-m and 1-km efforts of the 30-km trial were correlated with VO2max, PPO, and the power output at the second ventilatory threshold (r = .58–.82). PPO was the only physiological attributed measured during the GXT to be correlated with performance during the 100-km cycling trial (r = .64).Conclusions:Many physiological variables from a reliable GXT were associated with performance over shorter (30-km) but not longer (100-km) stochastic cycling trials.

Metabolic and performance responses during endurance exercise after high-fat and high-carbohydrate meals

1998 ◽  
Vol 85 (2) ◽  
pp. 418-424 ◽  
Author(s):  
Helena A. Whitley ◽  
S. M. Humphreys ◽  
I. T. Campbell ◽  
M. A. Keegan ◽  
T. D. Jayanetti ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Oxygen Uptake ◽  
Endurance Exercise ◽  
Maximal Oxygen Uptake ◽  
Time Trial ◽  
Substrate Oxidation ◽  
High Fat ◽  
High Carbohydrate ◽  
And Performance ◽  
Fat Meal

We studied the effects of preexercise meal composition on metabolic and performance-related variables during endurance exercise. Eight well-trained cyclists (maximal oxygen uptake 65.0 to 83.5 ml ⋅ kg−1 ⋅ min−1) were studied on three occasions after an overnight fast. They were given isoenergetic meals containing carbohydrate (CHO), protein (P), and fat (F) in the following amounts (g/70 kg body wt): high-carbohydrate meal, 215 CHO, 26 P, 3 F; high-fat meal, 50 CHO, 14 P, 80 F. On the third occasion subjects were studied after an overnight fast. Four hours after consumption of the meal, subjects started exercise for 90 min at 70% of their maximal oxygen uptake, followed by a 10-km time trial. The high-carbohydrate meal compared with the high-fat meal resulted in significant decreases ( P < 0.05) in blood glucose, plasma nonesterified fatty acids, plasma glycerol, plasma chylomicron-triacylglycerol, and plasma 3-hydroxybutyrate concentrations during exercise. This was accompanied by an increase in plasma insulin ( P < 0.01 vs. no meal), plasma epinephrine, and plasma growth hormone concentrations (each P < 0.05 vs. either of the other conditions) during exercise. Despite these large differences in substrate and hormone concentrations in plasma, substrate oxidation during the 90-min exercise period was similar in the three trials, and there were no differences in performance on the time trial. These results suggest that, although the availability of fatty acids and other substrates in plasma can be markedly altered by dietary means, the pattern of substrate oxidation during endurance exercise is remarkably resistant to alteration.

A Carbohydrate Ingestion Intervention in an Elite Athlete Who Follows a Low-Carbohydrate High-Fat Diet

2018 ◽  
Vol 13 (7) ◽  
pp. 957-960 ◽  
Author(s):  
Christopher C. Webster ◽  
Jeroen Swart ◽  
Timothy D. Noakes ◽  
James A. Smith
Keyword(s):  
High Intensity ◽  
Time Trial ◽  
Endurance Performance ◽  
High Fat ◽  
Carbohydrate Ingestion ◽  
High Intensity Training ◽  
Low Carbohydrate ◽  
Elite Level ◽  
And Performance ◽  
Intensity Training

This case study documents the performance of an elite-level, exceptionally well-fat-adapted endurance athlete as he reintroduced carbohydrate (CHO) ingestion during high-intensity training. He had followed a strict low-CHO high-fat (LCHF) diet for 2 y, during which he ate approximately 80 g of CHO per day and trained and raced while ingesting only water. While following this diet, he earned numerous podium finishes in triathlons of various distances. However, he approached the authors to test whether CHO supplementation during exercise would further increase his high-intensity performance without affecting his fat adaptation. This 7-wk n = 1 investigation included a 4-wk habitual LCHF diet phase during which he drank only water during training and performance trials and a 3-wk habitual diet plus CHO ingestion phase (LCHF + CHO) during which he followed his usual LCHF diet but ingested 60 g/h CHO during 8 high-intensity training sessions and performance trials. After each phase, rates of fat oxidation and 30-s sprint, 4-min sprint, 20-km time trial (TT), and 100-km TT performances were measured. Compared with LCHF, 20-km TT time improved by 2.8% after LCHF + CHO, which would be a large difference in competition. There was no change in 30-s sprint power, a small improvement in 4-min sprint power (1.6%), and a small reduction in 100-km TT time (1.1%). The authors conclude that CHO ingestion during exercise was likely beneficial for this fat-adapted athlete during high-intensity endurance-type exercise (4–30 min) but likely did not benefit his short-sprint or prolonged endurance performance.

Effect of Low- and High-Glycemic-Index Meals on Metabolism and Performance During High-Intensity, Intermittent Exercise

2010 ◽  
Vol 20 (6) ◽  
pp. 447-456 ◽  
Author(s):  
Jonathan P. Little ◽  
Philip D. Chilibeck ◽  
Dawn Ciona ◽  
Scott Forbes ◽  
Huw Rees ◽  
...  
Keyword(s):  
Glycemic Index ◽  
Muscle Glycogen ◽  
High Intensity ◽  
Perceived Exertion ◽  
Intermittent Exercise ◽  
Random Order ◽  
Rating Of Perceived Exertion ◽  
Repeated Sprint ◽  
High Glycemic Index ◽  
And Performance

Consuming carbohydrate-rich meals before continuous endurance exercise improves performance, yet few studies have evaluated the ideal preexercise meal for high-intensity intermittent exercise, which is characteristic of many team sports. The authors’ purpose was to investigate the effects of low- and high-glycemic-index (GI) meals on metabolism and performance during high-intensity, intermittent exercise. Sixteen male participants completed three 90-min high-intensity intermittent running trials in a single-blinded random order, separated by ~7 d, while fasted (control) and 2 hr after ingesting an isoenergetic low-GI (lentil), or high-GI (potato and egg white) preexercise meal. Serum free fatty acids were higher and insulin lower throughout exercise in the fasted condition (p < .05), but there were no differences in blood glucose during exercise between conditions. Distance covered on a repeated-sprint test at the end of exercise was significantly greater in the low-GI and high-GI conditions than in the control (p < .05). Rating of perceived exertion was lower in the low-GI condition than in the control (p = .01). In a subsample of 5 participants, muscle glycogen availability was greater in the low- and high-GI conditions versus fasted control before the repeated-sprint test (p < .05), with no differences between low and high GI. When exogenous carbohydrates are not provided during exercise both low- and high-GI preexercise meals improve high-intensity, intermittent exercise performance, probably by increasing the availability of muscle glycogen. However, the GI does not influence markers of substrate oxidation during high-intensity, intermittent exercise.

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