Several studies have looked into the effects of low-carb diets on high-intensity endurance exercise. In fact, a moderate-carb, higher-protein diet seems to be optimal for muscle growth and body composition for people who are lean and active . In contrast, a well-formulated ketogenic diet is more restrictive, usually consisting of only 30–50 grams of carbs per day, combined with a very high fat intake . This puts fat at a little under 10 percent of the daily calories, which would meet the standard definition of a Very Low Fat diet.
In the last few decades or so, athletes and scientists have experimented extensively with different dietary procedures to improve body composition, muscular strength and power, as well as overall work capacity . Recent studies have focused on a novel concept called “train low” to prepare athletes for competition . Some from the scientific community are currently strong proponents of these movements . [The impact on metabolic and reproductive diseases of low-carbohydrate and ketogenic diets]. Future research on carbohydrate-restriction in athletes could also address aspects of health alongside performance – both quantitively and qualitatively.
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A Carbohydrate Ingestion Intervention In An Elite Athlete Who Follows A Lchf Diet
Some individual responses to a ketogenic diet have shown dramatic benefits in both fat metabolism and performance, and are worth further investigation . Keto-adaptation enhances exercise performance and body composition responses to training in endurance athletes. Some low-carb diets may have health benefits beyond weight loss, such as reducing your risk of type 2 diabetes and metabolic syndrome. Even these endurance athletes will still need to consume carbohydrates during competition for optimal performance, albeit at a relatively much lower level than an endurance athlete competing in a single-day event like a short-course triathlon or a marathon. At the present time, the research does not show that a low-carb or ketogenic diet can improve high-intensity sports performance, compared to a higher-carb diet. As of now, no research has shown that low-carb or ketogenic diets are better for high-intensity, strength or power-based sports.
Jabekk PT, Moe IA, Meen HD, Tomten SE, Hostmark AT.. Resistance training in overweight women on a ketogenic diet conserved lean body mass while reducing body fat. Preliminary evidence suggests a ketone monoester drink may improve cycling time-trial performance but a diester may impair performance, and athletes should periodize CHO intake during training, to maximize skeletal muscle adaptations and align with the goals of the training session. Cutting calories and carbs may not be the only reason for the weight loss with low-carb diets. Some studies show that you may shed some weight because the extra protein and fat helps you feel full longer, which helps you eat less. Some low-carb diets greatly restrict carbs during the initial phase of the diet and then gradually increase the number of allowed carbs. To summarize, there truly is no “perfect” or “ideal” dietary approach for endurance athletes.
Recent Findings In the setting of adequate dietary protein consumption, research suggests some benefit particularly in sport or exercise activities. Summary Protein supplements command a multi-billion-dollar market with prevalent use in sports. Many individuals, including athletes, do not consume optimal dietary protein on a daily basis. High-protein diets are remarkably safe in healthy subjects, especially in the short term. Some objective outcomes are physiologic and may not translate to clinically relevant outcomes.
Impact Of Ketogenic Diet On Athletes: Current Insights
If you’re not consuming sufficient carbohydrates, you’ll likely need to take a supplement. While a keto marathon training plan can reduce carbohydrate utilization during exercise, there have not been any reported ergogenic benefits. In other words, you likely won’t achieve your PR if you’re following a low carb diet for exercise. There is sound evidence that high carbohydrate availability is desirable in the competition setting where it may contribute to optimal performance.
There simply isn’t enough research yet to discount this dietary strategy for endurance performance. However, studies of elite athletes chronically adapted to low-carbohydrate diets has uncovered one unexpected finding— their extraordinary ability to produce energy at very high rates purely from the oxidation of fat. Incorporating more fat and protein in response to the reduction of dietary carbs has led to concerns on the effect of low-carb dieting on lipids; specifically, LDL cholesterol. Recent systematic reviews of low-carb diets on lipids demonstrate a neutral to a small increase in LDL but a favorable triglycerides reduction and an increase in HDL cholesterol, particularly those assigned to the very low-carb intervention.
A 4-fold increase in plasma glycerol in combination with a much smaller increase in plasma NEFA during intermittent sprints also indicated a significant contribution of fat utilization and the aerobic metabolism (Chang et al., 2015; McCartney et al., 1986). In addition, subjects with greater aerobic capacity are more able to maintain power output during later stages of repeated sprints (Bishop and Edge, 2006; Brown et al., 2007). Thus, the increased fat oxidation rate and muscle-glycogen sparing effect after long-term adaptation to LCHF diets may be helpful to maintain and/or improve performance in latter stages in these sports. Before medications, carbohydrate control has been the cornerstone of glycemic control in both type 1 and type 2 diabetes. These enzymatic changes after LCHF diets may account for the increase in the fat oxidation rate. The potential effects of long-term adaptation to LCHF diets on endurance performance are presented in Figure 1.
Peak Endurance Solutions offers a variety of services for endurance athletes, including Training Plans available for purchase in the TrainingPeaks store as well as individualized, sport-specific coaching and one-on-one and small group swim instruction. Ryan holds a Masters degree in Exercise Science with a minor in Nutrition from Arizona State University. He is a Certified Strength and Conditioning Specialist® (CSCS®) through the National Strength and Conditioning Association and a USA Triathlon Level I Coach.
Although the current research seems to indicate that a more traditional, HCLF dietary approach is better-suited for overall endurance performance, research often doesn’t take into account individual differences between athletes. Additionally, there may be cases in which a LCHF diet may be beneficial for performance in some athletes. Humans do have a very limited store of carbohydrates and a nearly unlimited store of fat to draw upon to fuel exercise. Humans also rely heavily on fat to fuel exercise at lower-intensities , with the reliance on carbohydrates to fuel performance increasing with an increasing exercise intensity. In other words, fat utilization is highest during low-intensity aerobic exercise, such as an easy cycling, running, or swimming session. Additionally, several studies have shown that low-carb and ketogenic diets can help people lose weight and improve overall health .
Data are means ± SD with individual results identified (and mean changes from HCHO to K‐LCHF in respiratory exchange ratio provided in brackets). This topic is of great interest to me, as I have had personal experience with both high-carbohydrate diets and low-carbohydrate diets. As a competitive amateur triathlete, I am always looking for ways to safely and effectively improve my performance. Alongside proper sport-specific training, optimal rest and recovery, and effective mental preparation, dietary habits represent a rather significant target area for performance improvements.
Some studies revealed that individuals who consumed the LCHF diet experienced greater body weight and fat mass loss than those adhering to other dietary interventions, such as a calorie-restricted diet or low-fat diet [9,10.11], … In many field-based sports such as soccer, rugby, basketball, and hockey, the ability to perform multiple sprints at the highest speed after short rest is crucial for game performance (Rampinini et al., 2007; Ross et al., 2015; Spencer et al., 2005). Although a single sprint relies mostly on the anaerobic metabolism, repeated sprints significantly increase the demand for the aerobic metabolism during the later stages of exercise. In 10 × 6-s sprints separated by 30 s rest periods, the anaerobic metabolism provided most energy in the first sprint, but it fell to approximately 60% in the last sprint (Gaitanos et al., 1993a; Girard et al., 2011). On the other hand, the proportion of energy from the aerobic metabolism increased from almost zero in the first sprint to 40% in the last one (Girard et al., 2011).
A major goal of training to improve the performance of prolonged, continuous, endurance events lasting up to 3 h is to promote a range of physiological and metabolic adaptations that permit an athlete to work at both higher absolute and relative power outputs/speeds and delay the onset of fatigue (i.e., a decline in exercise intensity). Consequently, to sustain muscle energy reserves and meet the daily demands of training sessions, competitive athletes freely select CHO-rich diets. Despite renewed interest in high-fat, low-CHO diets for endurance sport, fat-rich diets do not improve training capacity or performance, but directly impair rates of muscle glycogenolysis and energy flux, limiting high-intensity ATP production. When highly trained athletes compete in endurance events lasting up to 3 h, CHO-, not fat-based fuels are the predominant fuel for the working muscles and CHO, not fat, availability becomes rate limiting for performance. However, endurance performance, measured by time trials after fixed-intensity prolonged exercise, was maintained in elite cyclists when muscle glycogen was restored with a 1-day high-carbohydrate diet after 5-6 days of a LCHF diet .
The ketogenic diet (“keto” for short) has become a very trendy word over the past year. As discussed in the journal, Sports Medicine, carb loading may extend steady state exercise by about 20%, and improve performance by about 2-3% in which a set distance is covered as quickly as possible. We can also increase intake during exercise and during the refueling and recovery period.
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