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It is now loadingg accepted that carbohydrates carohydrate perhaps the most important energy substrate for elite performance [ carvohydrate2 ]. Carbohydrate metabolism and carbohydrate loading, this Carbohydrate metabolism and carbohydrate loading not always been the case.
At metabolosm start of the modern Olympic Games inprotein was thought to be the most important Natural anti-inflammatory source for athletes [ 3 meetabolism Research showing the importance of loxding for performance began to emerge as early as the s [ Carbohydrate metabolism and carbohydrate loading ].
Further seminal work conducted in the s [ 5 ], as reviewed elsewhere [ 36 ], clarified Lloading importance of dietary carbohydrates for exercise and in particular the role of ketabolism glycogen in Carbohyerate performance.
However, it was only at the Loaving Olympic Games in that an megabolism of the importance ,oading dietary amd among athletes and coaches started to emerge [ 3 ]. Over this period, understanding Carbohyerate the actions of dietary carbohydrates on exercise metabolism and performance metaboliem increased substantially and, in concert, nutritional recommendations for athletes have developed and continue to evolve to reflect Carbohydrate metabolism and carbohydrate loading knowledge and practice.
Nonetheless, scientific unknowns remain that, if addressed, could Carbouydrate athletes with Carbohydate more detailed and tailored recommendations to metanolism them to reach their athletic potentials. The purpose of this narrative review is to Energy-boosting stretches contemporary perspectives and discuss areas for future research Carbohydratr application regarding the role of dietary carbohydrates for endurance athletes.
The article is structured around three Carbohyddate sections: 1 the importance of carbohydrates for competition and Carbohydrafe training sessions; 2 carbohydrates and training adaptation; Carbojydrate 3 personalizing carbohydrate intake.
Loadin energy availability loadimg Carbohydrate metabolism and carbohydrate loading is required for athletes to sustain Carbohydrage demands of competition and recover for subsequent competitions [ Carbohydraate ]. Undertaking intense exercise sessions i.
Additionally, the Physical activity for diabetic patients to perform high-intensity sessions relies heavily on activation of carbohydrate metabolic pathways Carbohydrwte 13 ]. While energy for adenosine triphosphate ATP production can ,oading derived both Kids healthy eating fats and carbohydrates, it is carbohydrates that are primarily carbohyxrate at high Carbohydrate metabolism and carbohydrate loading intensities [ 14 xnd, 15 ].
Evidence liading that utilization of carbohydrates and not fats is crucial to sustain the exercise intensities observed in elite Carbohydrate metabolism and carbohydrate loading [ 1617 ]. However, metsbolism importance Carblhydrate an metaolism to oxidize fats at high intensities should not be discounted [ 18 ], as a valid method to quantify its contribution to Koading production during exercise at Plant-based physical performance enhancer intensities is yet to be established [ 19 ].
Metabolizm has been known for decades that loadig carbohydrate Coenzyme Q can influence exercise capacity cqrbohydrate 27 ].
The ability to store muscle glycogen increases with improved training status [ 28 ]. While storage capacity is increased in highly trained populations, it appears that at the time of exhaustion, muscle glycogen concentrations are lower in untrained i.
Recently, understanding of the underpinning mechanisms responsible for improved exercise capacity with elevated glycogen stores has improved. It has been demonstrated that glycogen loading increases exercise capacity by sparing of the intra-myofibrillar glycogen pool and that the intra-myofibrillar pool in type I muscle fibers is the best predictor of prolonged exercise capacity [ 29 ].
During high-intensity exercise efforts e. As a result of the plethora of research demonstrating the importance of muscle glycogen availability, strategies have been devised on how to optimally stimulate muscle glycogen synthesis in the days leading up to competition, a strategy also known as carbohydrate or glycogen loading [ 132 ].
To achieve muscle glycogen loading, athletes are recommended to consume a very high carbohydrate diet i. However, it is common for athletes to undertake an exercise session in this time frame, during which some of the stored glycogen will be used.
In addition, some sports events e. Indeed, evidence indicates that maintaining high muscle glycogen concentration could be difficult in these circumstances [ 33 ].
More research is required to understand how to better sustain glycogen loading over multiple days, but most likely optimized recovery practices and in-race feeding strategies will represent the most effective ways to maintain adequate carbohydrate availability.
In addition to this, more research is required to better understand how, and if it is possible to, affect skeletal muscle glycogen storage localization by diet manipulation, especially when time for carbohydrate ingestion is limited.
A greater understanding of whether different types of carbohydrate affect the storage localization within muscle is also warranted.
While muscle glycogen depletion is more commonly associated with prolonged strenuous endurance exercise, even short but intense exercise bouts can result in significant reduction of muscle glycogen content [ 303435 ]. Thus, one could assume that because of this, glycogen loading would be warranted.
However, the evidence is not as conclusive, as glycogen loading before shorter duration events does not always translate into performance improvements [ 3036 ].
For instance, Sherman and colleagues showed that for runners undertaking a half-marathon, glycogen loading was of no benefit to performance [ 36 ]. Based on this, it is not currently recommended to perform glycogen loading for events shorter than 90 min [ 32 ].
This is especially pertinent for sports where increased BM could significantly hinder performance by reducing sustainable relative exercise intensity e. However, it is important to discern between functional BM i.
Whether liver glycogen stores can also be super compensated remains to be established, as currently there is no clear evidence that this is possible [ 20 ]. Varying carbohydrate intake does indeed change fasting liver glycogen concentrations [ 41 ], and this shows that sufficient carbohydrate intake is required to start an exercise session with normal liver glycogen stores.
However, whether glycogen stores could be increased to higher-than-normal levels remains to be established. It is often overlooked that if competition is to be performed in the morning after an overnight fast or any period of prolonged fastingliver glycogen stores may be compromised. Namely, in the postabsorptive phase e.
On the contrary, muscle glycogen stores are typically not affected by an overnight fasting period [ 42 ]. As numerous competitions start in the morning, it is pertinent that the meals after overnight fast are designed so that there is a focus on liver glycogen repletion. While this has not been directly assessed, it could be speculated that providing athletes with a mix of different types of monosaccharides would be beneficial.
This suggestion is based on previous observations that combining glucose-based carbohydrates with either fructose or galactose offer benefits on liver glycogen synthesis over glucose-based carbohydrates only [ 434445 ].
Indeed, a recent study found improved exercise capacity with a breakfast consisting of fructose-glucose-based carbohydrates as compared to glucose-based carbohydrates only [ 46 ]. This would advance practical advice not only from the perspective of optimization of liver glycogen levels, but also from the perspective of preventing consequences of rebound hypoglycemia, which can occur in some athletes when exercise bouts are initiated close to a meal [ 47 ].
Current nutritional guidelines for athletes advise to consume carbohydrates during exercise at different rates and in relation to the duration of exercise bouts, as will be discussed later [ 12 ]. There are currently two proposed mechanisms of carbohydrate ergogenicity.
Firstly, carbohydrates can be sensed in the oral cavity, causing an activation of certain brain regions, leading to stimulation of the central nervous system, as shown by improved performance by carbohydrate mouth rinsing [ 495051 ].
Secondly, and most importantly, carbohydrates provide an additional fuel source for ATP formation during exercise. Carbohydrate ingestion during exercise maintains stable blood glucose levels over long exercise sessions [ 52 ] and maintains carbohydrate oxidation rates despite declining muscle glycogen stores so that ingested carbohydrates substitute endogenous carbohydrate stores [ 5354 ].
In addition to this, exogenous carbohydrates can spare or even completely suppress liver glycogen breakdown [ 5556 ]. While some studies have found sparing of muscle glycogen with carbohydrate supplementation during exercise [ 5758 ], most of the studies assessing whole muscle glycogen utilization did not see this effect [ 28 ] and a recently published study that evaluated different carbohydrate ingestion rates during cycling exercise did not observe sparing of muscle glycogen in a muscle fiber type-specific manner either [ 59 ].
However, more recent evidence indicating the importance of compartmentalized glycogen metabolism to muscle function opens new avenues for investigating the mechanistic basis of carbohydrate feeding during exercise [ 29 ].
Galactose has typically not been recommended to be ingested during exercise due to a belief that it is not as readily oxidized [ 6162 ]. However, recent evidence demonstrates that at moderate dosages i. It remains to be demonstrated directly, but these data indicate that oxidation of galactose during exercise is not limited when provided as lactose at moderate ingestion rates.
Thus, lactose as a source of galactose and glucose can be ingested as an alternative carbohydrate source during exercise, at least in lactose-tolerant individuals. It is believed that at this ingestion rate, the sodium-glucose linked transporters SGLT1 in the small intestine become saturated [ 25 ].
This notion is based on the observations that when fructose, whose absorption from the small intestine utilizes a different transporter i.
As a result of this, athletes are recommended to ingest mixtures of glucose- and fructose-based carbohydrates when training or competition is longer than 2. Most studies investigating combined ingestion of glucose-based carbohydrates and fructose utilized a glucose:fructose ratio, and this has since become a standard recommendation [ 60 ].
However, a closer examination of the literature reveals that a ratio closer to unity i. Thus, it could be recommended that composite glucose- and fructose-based carbohydrates in a ratio close to unity are ingested irrespective of exercise duration.
The suggestion that glucose-fructose mixtures be recommended over single transportable carbohydrates even when exercise duration lies within 1—2. Most studies to date investigating exogenous carbohydrate oxidation rates have been performed on moderately to highly trained athletes, but not in elite athletes whose absolute energy demands can be vastly higher.
However, endogenous carbohydrate oxidation was not further spared by the higher carbohydrate dose, and thus whether there would be an additional performance benefit requires clarification.
Current evidence indicates that glucose delivery to the active tissue i. Bypassing intestinal absorption by infusing glucose and maintaining glycaemia did not result in higher exogenous glucose oxidation rates [ 74 ], whereas infusing glucose to maintain hyperglycemia i.
This occurred without a reduction in muscle glycogen use, but rather with suppression of fat oxidation rates. As oral ingestion of very large amounts of glucose i. Yet, evidence for recommending such high ingestion rates i.
It could be that athletes whose energy turnover rates during exercise are very high and thus have a high glucose flux to muscle due to increased blood flow proportional to absolute exercise intensity [ 83 ] could benefit from carbohydrate ingestion rates that are higher than currently recommended, but this requires further evaluation.
Additionally, it remains to be established what occurs at intensities in heavy and severe exercise intensity domains, as some evidence indicates that despite higher carbohydrate demands, exogenous carbohydrate oxidation rates do not further increase [ 84 ].
Nonetheless, at present, it cannot be recommended to alter the currently recommended maximal carbohydrate ingestion dose during endurance exercise i. There have been many attempts to increase exogenous carbohydrate oxidation rates by co-ingestion of carbohydrates with other nutrients or nutritional supplements, a topic recently reviewed by Baur and Saunders [ 85 ].
: Carbohydrate metabolism and carbohydrate loading| Publication types | Katz A, Broberg S, Sahlin K, Wahren J. When comparing exercise at the same relative exercise intensity between hypoxia and normoxia, there appear to be no differences in substrate oxidation rates [ ], whereas if the absolute intensity is matched, there is an increase in carbohydrate oxidation rates [ ]. Furthermore, the participants was not randomly selected and could thus limit the generalisability of the study. Accessed 2 Aug A recent study indicated that the capacity to utilize fat during exercise in an overnight fasted state is best correlated with CS activity [ ], a marker of mitochondrial content [ ] that is itself well correlated with training volume [ ]. Reprints and permissions. Article CAS Google Scholar Jeukendrup AE. |
| How Does Carb Loading Work? | Carbohydrates are Carbohydratw up of small molecules of lpading, or saccharides, that when combined Carbohydrate metabolism and carbohydrate loading various ways form different types of carbohydrates. Metabolism and nutrient partitioning, at present, it cannot Carbohydrate metabolism and carbohydrate loading recommended carbohydrats alter the currently recommended maximal carbohydrate ingestion dose during endurance exercise i. Diabetes Care. Yet, evidence for recommending such high ingestion rates i. Namely, two studies [] quantified utilization of in-recovery ingested carbohydrates in the subsequent exercise bout and found an increase in its use, indicating an increased carbohydrate availability. Am J Physiol ; —9. |
| Access this article | Psychosom Med. Schabort, Timothy D. Gastric emptying during exercise: effects of heat stress and hypohydration. Cesare Granata X, Oliveira RSF, Little JP, Bishop DJ. The effect of carbohydrate mouth rinse on 1-h cycle time trial performance. Firstly, carbohydrates can be sensed in the oral cavity, causing an activation of certain brain regions, leading to stimulation of the central nervous system, as shown by improved performance by carbohydrate mouth rinsing [ 49 , 50 , 51 ]. |
| What is carb loading? | Results: Mean glucose values during CHO-loading were: day 1; Mean sensor glucose at start of PE was Percentage of time spent in range TIR respective time spent in hypoglycemia was: CHO-loading Conclusions: High intermittent CHO-intake during prolonged PE combined with proactive use of rtCGM is associated with good glycemic control during prolonged exercise in individuals with diabetes type 1. However, the time spent in hypoglycemia during the 2-days of CHO-loading was Clinical Trial Registration: www. gov , identifier NCT Studies have shown that individuals with diabetes type 1 have the same aerobic capacity as healthy individuals, provided that blood glucose BG is maintained in the euglycemic range 1 , 2. However, in individuals with diabetes type 1, physical exercise PE is associated with an increased incidence of both hypoglycemia and hyperglycemia 3 , 4. Whether the aim of PE is to have fun, become physically fit, lose weight or to increase the physical performance, the general glucose management strategy during PE is to avoid hypoglycemia. Depending on the specific aim, different strategies are required to obtain stable glucose control which could be achieved via alterations in the carbohydrate CHO intake or insulin adjustments or a combination of these. In healthy subjects, new guidelines are available 5 , with information on optimal CHO-intake for PE with various durations in order to ensure maximum performance and achieve stable blood glucose levels 5. The high CHO-intake contributes to a maintained high rate of CHO oxidation necessary to sustain the exercise intensity and to reach better performance 6. In the absence of such recommendations, the individuals must adopt a trial-and-error approach based on their past experience of BG responses to similar activities 7 , 8. In healthy individuals an increased intake of carbohydrates, such as carbohydrate loading CHO , is automatically accompanied by an increased insulin secretion with maintenance of a stable glucose level. In individuals with type 1 diabetes, this automatic regulation is missing and to our knowledge, only one study has been published investigating the effect of CHO-loading on physical performance and blood glucose control In this study, the glucose control deteriorated along with impaired physical performance and it was concluded that a high CHO diet prior to PE was not recommended in the case that blood glucose control cannot be maintained in individuals with type 1 diabetes. Given the limited knowledge, it is therefore important to develop effective CHO-loading models for the individual with type 1 diabetes. However, during competition, problems with hyperglycemia is often seen and is due to stress-induced release of glucose elevating stress hormones such as adrenaline and noradrenaline 7 , 8 , A hyperglycemia at this time might result in avoidance of ingesting CHO at the start of the race and, which in turn can result in a late onset hypoglycemia, due to the increased requirements of CHO during the PE have not been met 8. Furthermore, during prolonged PE, the carbohydrate intake has primarily been governed by the current blood glucose value or trend in previous studies 7 , 8 instead of actually adding the amount of CHO required for the duration and intensity of the exercise. This reversed approach was evaluated when individuals with type 1 diabetes conducted a 90 km cross-country skiing race Vasaloppet In this study, the adjustments of insulin doses were individualized and slightly increased for the majority of participants. This strategy resulted in a maintained good glycemic control during the race. With technological developments in recent years it is not only possible to accurately assess glucose control but also to take preventive actions. Real-Time Continuous Glucose Monitoring rtCGM has been shown to improve glycated hemoglobin A1c as well as reducing the risk of hypoglycemia As hypoglycemia and hyperglycemia is associated with PE, rtCGM may therefore improve glucose management related to PE The rtCGM allowed access to combined glucose information such as; actual value, glucose trend and direction and rate of the glucose changes. This information could be used to promote proactive actions, to reduce the glucose variability and if sustained also to reduce the A1c level 13 — The aim of this study was to evaluate CHO-loading prior to and intermittent high carbohydrate intake during prolonged PE in individuals with type 1 diabetes and its impact on glycemic control when applied along with rtCGM. Physically active individuals with type 1 diabetes from different regions of Sweden reported their interest to participate in the study and 10 individuals were selected. Exclusion criteria: A1c 8. This is a descriptive, single arm, non-randomized interventional study. The intervention consisted of CHO-loading prior to and intermittent high CHO-intake during PE and a proactive use of rtCGM to achieve and maintain glucose control. A 3-day long sports camp was performed 1. The objective of this sport camp was to educate and prepare the participants on CHO-loading and the extended use of CHO during PE. All participants used rtCGM during the sports camp, the time between the sports camp and the Vasaloppet as well as during the race. All participants conducted a 2-day CHO-loading twice, first during the time interval between the sports camp and the Vasaloppet and later during the 2 days prior to the race. The first occasion was used as an exercise in adjusting the insulin doses. The extended CHO-intake was simultaneously balanced with an increased amount of basal insulin where the individual carbohydrate to insulin ratio was used to find the appropriate dose to add as a basal dose during the subsequent 12 h. Extra bolus doses were used during daytime corresponding to the added carbohydrate amount. Supplementary File 1 illustrates the CHO-loading procedure including recommended insulin dose adjustments. The breakfast was consumed at least 2 h before the start of PE and the participants were given a breakfast they were used to consume in relation to PE. The participants were informed to consume extra CHO about 20—25 g in the form of a sport drink, or to use a min pump suspension, if the glucose level tended to decrease toward hypoglycemia before start, thus using the rtCGM proactively. During all exercise sessions, the participants consumed a glucose—fructose containing liquid, three times per hour. The use of this mixed glucose-fructose sports drink enabled the extended use of CHO, corresponding to 1. The Dexcom G5 Platinum system Dexcom, San Diego, CA was used during the study period. The sensors were inserted and calibrated according to company recommendation. The rtCGM devices and insulin pumps were downloaded via Diasend Glooko Inc. All participants utilized the information they received via rtCGM but received no further instructions on glucose management during the race. Hypoglycemia: Glucose value The statistical package for the social sciences SPSS version Glucose values are presented as mean ± standard deviation unless otherwise indicated. Ten individuals, mean age The baseline characteristics of the study population is shown in Table 1. During the CHO-loading prior to the Vasaloppet, one participant had problems with the rtCGM equipment during day 1 resulting in missing data. Mean glucose during the 2-day CHO-loading were: for both days; The distribution of glucose values in TIR, hyperglycemia and hypoglycemia is shown in Table 3. Table 2. Mean glucose levels measured by rtCGM in individuals with type 1 diabetes during a 2-day carbohydrate loading prior to Vasaloppet. Table 3. Glucose values in individuals with type 1 diabetes during 2 days of carbohydrate loading and during a 90 km cross-country skiing race Vasaloppet. The mean insulin bolus dose before the race was increased by Mean sensor glucose levels at the start a. of the race was Table 4. Mean glucose levels, carbohydrate intake, and adjustment of basal insulin in individuals with type 1 diabetes during a 90 km cross-country skiing race Vasaloppet and the duration of the physical activity A—J. Mean sensor glucose during the race was The percentage of TIR was Each participant's glucose graph is shown in Figure 1. Figure 1. Continuous glucose monitoring graphs of 10 individuals with type 1 diabetes during the 90 km cross-country skiing race Vasaloppet. The time needed to complete the race, CHO-intake and basal insulin dose adjustments are illustrated in Table 4. In this study we have shown that it was possible to achieve and maintain good glycemic control, even during extraordinary challenges such as 2 days of CHO-loading followed by high intermittent CHO-intake during a 90 km long cross-country skiing race. A proactive use of rtCGM enabled individual insulin dose adjustments under these conditions. To our knowledge few studies have been published regarding models for carbohydrate loading in type 1 diabetes individuals and the same also applies for the use of high carbohydrate intake during prolonged physical exercise. In the study by McKewen et al. In contrast to this we obtained preserved glucose control during a 2-day carbohydrate loading. Studies have suggested that increased muscular glycogen content increases insulin resistance which could explain why the participants required more insulin during night 2 17 — It might be suggested that a slightly lower basal insulin rate could be recommended in the present study considering that It should also be considered that individuals with type 1 diabetes usually face problems with hypoglycaemia on regular basis. This will affect the counterregulatory hormonal response and attenuate endogenous hepatic glucose production during exercise and might therefore result in an increased risk of hypoglycaemia during a subsequent physical activity Thus, avoidance of a hypoglycemia the day before prolonged physical activity is most likely even more important with the approach presented in this study where the basal doses were not reduced before and during the race. Prior to competitions, stress is common, causing increased release of adrenaline and noradrenaline This stress results in hyperglycemia 7 , 8 , Beyond this fact, individuals with type 1 diabetes often have a fear of hypoglycemia associated with PE, which often results in a reduction of the basal insulin dose before the start of the race In a recent publication Riddell et al. showed that the variability of glucose control during aerobic exercise partially was explained by pre-exercise glucose level Our approach was to reach a stable and good glucose control prior to the start of the race. To reduce the risk of hyperglycemia in this study, first the participants did not have to reduce basal insulin before and during the competition due to the plan we had about using an extended amount of CHO throughout the race. Second, the participants increased the insulin dose to the meal taken 2. To our knowledge there are no previous studies using this novel model. The rtCGM, used in our study, provided safety to this approach as the individual could be warned about pending hypoglycemia and consume a liquid CHO solution in such occasions. Both hypoglycemia and hyperglycemia are important to avoid during PE when performance also is regarded as an important factor. Hyperglycemia increases the release of free fatty acids FFA An increase in FFA has been shown to decrease both insulin-dependent and insulin-independent muscular glucose uptake 24 — In one of these studies an increase in plasma FFA up to In addition, an increase in plasma FFA will reduce muscle CHO oxidation, which may adversely affect physical performance Despite the prolonged duration of the PE in the current study, the participants spent In the same study, mean plasma free insulin levels in the individuals with type 1 diabetes before the race were half 7. Thus, compared to this study, we were able to achieve a better glycemic control at start and then also to maintain this glucose control during prolonged PE. A possible mechanism behind the good results in our study could be the combination of carbohydrate loading and subsequent high carbohydrate intake during prolonged physical exercise. This procedure ensured a relatively high glycogen content in the liver and muscles prior to exercise. The main focus of this study was to continuously ingest increased amounts of carbohydrates to maintain a high carbohydrate availability throughout the race and thereby hopefully achieve a preserved blood glucose value. However, it should be highlighted that an increased intake of carbohydrates during exercise does not seem to spare muscle glycogen 29 , Instead, studies have shown that an increased carbohydrate intake spare the liver glycogen which likely supports both a stable blood glucose and performance in the latter stages of prolonged exercise 31 , Gastrointestinal discomfort is very common symptom during exercise, especially in prolonged endurance races The occurrence of gastrointestinal disturbances has been related to the CHO-intake during exercise However, it has been shown that the gut is adaptable in that the intestinal capacity to absorb CHO can be increased by regularly consuming increasing amounts of CHO during exercise 35 , Unfortunately, one participant had to deviate from the planned CHO-intake during the race due to gastrointestinal discomfort. This deviation resulted in a reduction of the planned basal insulin dose. This participant had, due to an upper respiratory infection, 2 weeks prior to the Vasaloppet, only completed a few exercise sessions with a higher intake of CHO before the PE. It is likely that this participant would have needed more exercise sessions with a high CHO-intake to increase the tolerance for high amounts of CHO. This study was performed as an exploratory study which includes the benefits of this being a real world situation. As opposed to this, there are of course also limitations as a control group is missing and where the environment made it difficult to carry out parallel sampling to evaluate the mechanisms behind the good glucose control achieved in the study. Furthermore, the participants was not randomly selected and could thus limit the generalisability of the study. Vasaloppet is a 90 km long cross-country skiing race which is very demanding in terms of individual physical performance and the participants had to have relative high level of fitness to be able to complete the race. Therefore, the results could be seen as a description of real-world data in this specific group. We conclude, that high intermittent CHO-intake during prolonged PE was associated with good glucose control in individuals with type 1 diabetes. However, the proportion of time spent in hypoglycemia during the 2-days of CHO-loading was rtCGM could be beneficial when used proactively to maintain sensor glucose values within target range before and during PE. These strategies and the mechanisms that create the conditions for good glucose control during prolonged physical exercise needs to be further evaluated in randomized controlled studies. All procedures performed in this study involving human participants were in accordance with the ethical standards of the national research committee and with the Helsinki declaration and its later amendments. Signed informed consent was collected from all participants prior to study start. SM and PA conceived and designed research, conducted the experiments, and analyzed data. JJ participated in the planning of the study. SM, PA, and JJ did all participate during the preparatory sports camp. SM wrote the manuscript. PA and JJ reviewed the manuscript. All authors read and approved the manuscript. This study was funded by an unrestricted grant from Novo Nordisk AS, Bagsværd, Denmark. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. We would like to thank all participants in the study providing us with new knowledge. During the second phase of carb loading when you consume higher-than-normal amounts , athletes may consume as much as 9 to 12 grams of carbs per kilogram of body weight per day. During the later stages of carb loading, you can facilitate more glycogen accumulation by doing light activity, like taking a short walk. And then the last day or two, you can prevent water retention and bloating if you eat a heavy meal and then go for a light walk: In studies, walks of 30 minutes after meals have been found to stabilize blood sugar after eating. Not everyone benefits from filling up their glycogen stores before an event, and even if carb loading prevents bonking, the discomfort may not be worth it:. Levels, the health tech company behind this blog, helps people get CGMs shipped directly to their door, and to understand their data to track meals and performance over time. Click here to learn more about Levels. Get updates, new articles, exclusive discounts, and more Email Required Comments This field is for validation purposes and should be left unchanged. The Explainer. Research suggests that eating protein and fat first might help reduce your post-meal blood sugar rise. The Levels Team. Ami Kapadia. Here are healthy sources and ways of eating carbohydrates. Stephanie Eckelkamp. Ultimate Guide. Switching between periods of low- and higher-carb intake may improve performance, gut health, and more. Find out if a carb-cycling plan is right for you. Zoë Atlas, MPH, RDN. Greg Presto. The glycemic index provides insight into how particular foods affect glucose but has limitations. Metabolic Basics. Being aware of these causes of inaccurate data can help you identify—and avoid—surprising and misleading feedback. Joy Manning, RD. Inside Levels. Levels Co-Founder's new book—Good Energy: The Surprising Connection Between Metabolism and Limitless Health—releases May 14; available for pre-order today. Metabolic flexibility means that your body can switch easily between burning glucose and fat, which means you have better energy and endurance. Jennifer Chesak. Written By Dominic D'Agostino, PhD. How Does Carb Loading Work? What Kinds of Exercise Does Carb Loading Work For? How can CGM help improve exercise performance? Read the Article. Interested in using a CGM to keep track of your carbs? Get updates, new articles, exclusive discounts, and more. Email Required. This field is for validation purposes and should be left unchanged. More on Nutrition. Nutrition The Explainer Can eating carbs last reduce blood sugar spikes? Nutrition Ultimate Guide What is carb cycling and how does it impact metabolic health? |
Carbohydrate metabolism and carbohydrate loading -
Some people make the mistake of choosing foods that are high in both carbohydrates and fat, rather than just carbs. For example, many desserts such as chocolate, ice cream and cookies fall into this category, as well as creamy pasta sauces and buttery breads.
Checking the nutrition information of foods you eat can help. Eating high-fiber foods could also be detrimental. Although fiber is part of a healthy diet , too much fiber during carb loading can cause stomach discomfort in some individuals Carb loading is a unique time when it could be better to choose white bread or pasta over whole wheat.
During this time, you should probably also avoid high-fiber foods like beans. Overall, it may be best to choose lower-fiber carbohydrate sources to avoid the possibility of fullness or stomach discomfort during exercise. Another possible mistake is not knowing if you are eating the right amount of carbohydrates.
Without recording what you eat, you may be eating too much or too little. Experts often recommend that people who are carb loading eat 2. Recording your food intake can help you make sure you are eating the right amount 3.
However, if you eat more carbs than necessary, you may have changed your diet too much or simply eaten too many calories. As your experience grows, you may not need to do this anymore.
However, it is a good idea for beginners. The days before your event or competition are important, and having an upset stomach due to unfamiliar foods can spoil your experience and exercise performance. Because of this, you should choose foods that are familiar to you — in addition to being high-carb, low-fat and low-fiber.
If you are considering using carb loading before an upcoming competition or athletic event, there are a few things you should think about. Before you launch into carb loading, consider whether the type and duration of exercise you are doing requires it.
If you will be performing exercise lasting more than 90 minutes without breaks, such as running or cycling, you may benefit from this nutrition strategy. If your exercise is shorter or involves many breaks, such as weight training, carb loading is probably not necessary.
If you record all the food you eat for several days using a food-tracking app or the nutrition labels on your food, you can calculate your current daily carbohydrate intake. Then you can divide the grams of carbs you eat each day by your weight to compare your current intake to carb loading recommendations.
For example, if you weigh pounds 70 kg and you normally eat grams of carbs per day, then you are consuming 1. People who are carb loading may eat 2. That said, experts often recommend a more limited range of 3. Based on these recommendations, you would need to eat approximately double the amount of carbs you would normally.
Avoid choosing foods that are high in both carbs and fats, such as desserts, pasta with creamy sauce, pastries and similar items.
As discussed, carb loading programs can last from one to six days. It may be a good idea to start with a simple program lasting between one and three days.
For example, you could simply increase your carb intake to around 3. You could also practice several different types of carb loading during training and keep notes to decide which helped you feel and perform your best.
Generally, it is best to experiment during your training rather than right before a real competition.
That way, you can decide what will work best before your big event. Lastly, it may be best to focus on familiar foods during carb loading. Unusual foods could upset your stomach and impair your performance. Commonly recommended foods include pasta, bread, fruits and fruit juices, smoothies, cereals and other high-carb, low-fat foods.
Once you have your nutrition plan set, you need to remember to taper your exercise in the days leading up to your event or competition. Summary Before you start carb loading, consider whether you will benefit from it.
You should also figure out how many carbs you normally eat so you know how much to change your regular diet.
Deciding the right duration for carb loading is also important. Of course, it is also important to have protein to support your muscles. Try to focus on lean protein sources, such as fish, lean cuts of meat or poultry and fat-free dairy.
Try to find the best compromise between the recommendations and foods you enjoy. Many people eat high-carb foods that are high-fat too.
It is best to avoid these during carb loading. Below are some examples of foods that may seem high-carb but are also high-fat and therefore inappropriate for carb loading.
Also, many foods that are a great part of your normal diet may be high in fiber. In lower intensity, carbohydrates may not be the major source of fuel, but they are required for the effective metabolism of fat, which is.
Thus carbohydrates are the limiting factor in exercise, meaning when carbs are depleted in either case, performance is dramatically reduced. From any viewpoint, this involves a switch from a normal balanced diet to an extreme.
Extremes often stimulate a controversial debate and there thus both a positive and negative side should be weighed up. Some simple facts on carbohydrate metabolism can help you decide to what extent and what method carbohydrate loading may be appropriate for you.
The lack of carbohydrates combined with high bouts of exercise during the depletion stage of traditional carbo-loading could elicit hypoglycemia signs are weakness, lethargy, and irritation.
Prolonged intense exercise during the depletion stage could also lead to muscle trauma which in fact would impair the storage of glycogen rather than enhance it. Furthermore, carbohydrate loading could lead to the destruction of muscle fibers by excessive glycogen storage.
Several lab studies have reported abnormal electrocardiograph patterns in individuals who use the classic method. Besides the irregular heartbeats and sudden loss of blood pressure, diarrhea, cramping, and nausea are often symptoms associated with drastic diet changes.
Glycogen is hydrophilic, meaning that it attracts water. Generally, athletes are advised to consume around 8 — 12 grams of carbohydrates per kilogram of body weight per day during the carb loading phase. In conjunction with increased carbohydrate consumption, it's important to implement an exercise taper during this period.
Reducing the intensity and volume of your workouts allows your muscles to recover and glycogen stores to be maximised. A useful tip would be to practise carb loading as part of training prior to the actual competition or event. This will allow you to experiment with different strategies, gauge their effectiveness, and make any necessary adjustments.
By doing so, you can optimise your performance and fuel your body effectively for the endurance challenge ahead. It's important to note that carb loading protocols may vary among athletes. To develop a personalised plan, it is recommended to discuss your specific needs with both a sports dietitian and physical trainer.
They can guide you through the process, fine-tuning the dietary and training aspects to suit your individual requirements. Carb loading doesn't mean you should increase your total daily calories. Rather, it involves adjusting the proportion of your calorie intake that comes from carbohydrates.
Overeating can lead to weight gain and feelings of heaviness or discomfort, which are not conducive to optimal performance. Do not neglect to consume sufficient fluids prior to an endurance event to ensure that you are adequately hydrated.
Failing to properly hydrate can lead to dehydration and negatively impact your performance and recovery. Another common mistake is not consuming enough carbohydrates to maximise glycogen stores.
For effective carb loading, aim for 8 — 12 grams of carbs per kilogram of body weight each day. The exact amount of carbohydrates required prior to an event should be discussed with a sports dietitian, as this will vary across different individuals and different types of sport.
This can come in the form of refined carbohydrates like bread, rice, and noodles. Although foods and drinks high in refined sugars, such as smoothies, cereal bars, and flavoured milks are generally not recommended on a regular basis, it is acceptable to use these foods and drinks to meet the higher-carbohydrate demands of carb-loading prior to endurance events.
Some athletes consume too much fibre while carb loading, leading to gastrointestinal discomfort. In the final days leading up to the event, switching to low-fibre carbohydrate sources such as white bread instead of wholemeal bread, or regular pasta rather than wholegrain pasta can help alleviate potential digestive issues.
Some people make the mistake of consuming high-fibre or fatty foods during their carb loading phase. Fatty foods can displace the carbs needed to fill glycogen stores, and while high -fibre foods like vegetables, whole grains and fruit are healthy and recommended on a regular basis, these should not be overconsumed during the carb loading phase because they can cause digestive discomfort especially if consumed in large amounts.
While the focus of carb loading is on carbohydrates, protein should not be completely overlooked. Including a moderate amount of protein in your meals can aid in muscle repair and recovery.
Speak to a sports dietitian to understand your individual protein needs and how adequate protein can be incorporated into a high-carbohydrate diet. The days leading up to a race are not the time to try a new dietary strategy. Every athlete is unique, and you should use your periods of training to trial and fine-tune your carb loading plan.
When carb loading, you should avoid high-fat and high-fibre foods and alcohol. Instead, what you should go for are foods that are high in carbohydrates and low in fibre to maximise glycogen storage and minimise digestive discomfort.
These include:. Refined grains. Choose white bread, white rice, or pasta. While whole grains are generally healthier, they're higher in fibre, which can lead to digestive discomfort when consumed in large quantities.
Refined grains, on the other hand, are more easily digested, and are therefore more appropriate to meet the high carb needs during carb loading.
Starchy vegetables. Potatoes and sweet potatoes without skin, as well as taro are some good choices. Fruit juices and canned fruits. These are high in simple sugars which are more carbohydrate-dense than fresh fruit.
It is acceptable to include foods and drinks high in refined sugars, such as juices, flavoured milk, canned fruit, and smoothies as part of the diet to meet the high carb needs during the carb loading phase.
Low-fat dairy. Milk, yogurt, and low-fat cheeses provide carbohydrates along with some protein for muscle recovery. Flavoured low-fat milks and yoghurt are a good way to provide lots of carbohydrates in a small volume. If you're interested in learning more about carb loading or are going to go on the diet for an upcoming event, our experienced dietitians can help.
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Your body uses carbs to supply metabilism with energy metabloism you exercise. Peak performance diet loading is one of the most Carbohydrate metabolism and carbohydrate loading of these nutritional tools, often Cafbohydrate Carbohydrate metabolism and carbohydrate loading athletes to Carbkhydrate their performance. It involves adjusting your diet and physical activity levels to boost the amount of carbohydrates stored in your body. This article explains carb loading, discusses common mistakes and gives recommendations for how to do it properly. Carbohydrates are a very important source of fuel for your body. During many types of exercise, your body uses stored carbs to provide you with energy 1. In the body, carbohydrate stores are called glycogen.
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