An 8-Week, Low Carbohydrate, High Fat, Ketogenic Diet Enhanced Exhaustive Exercise Capacity in Mice Part 2: Effect on Fatigue Recovery, Post-Exercise Biomarkers and Anti-Oxidation Capacity

Ketogenic diet and behavior: insights from experimental studies

As a journal page for full details. The ketogenic diet (KD) has been established as a treatment for epilepsy, but more recently it has been explored as an alternative or add-on therapy for many other diseases ranging from weight loss to neurological disorders. Animal models are widely used in studies investigating the therapeutic effects of the KD as well as underlying mechanisms. Especially in the context of neurological, psychiatric, and neurodevelopmental disorders essential endpoints are assessed by behavioral and motor tests. Here we summarized research evaluating the influence of the KD on cognition, depressive and anxiety-related behaviors, and social and nutritional behaviors of laboratory rodents. Each section contains a brief description of commonly used behavioral tests highlighting their limitations. Ninety original research articles, written in English, performed on mice or rats, providing measurement of blood beta-hydroxybutyrate (BHB) levels and behavioral evaluation were selected for the review. The majority of research performed in various disease models shows that the KD positively impacts cognition. Almost an equal number of studies report a reduction or no effect of the KD on depressive-related behaviors. For anxiety-related behaviors, the majority of studies show no effect. Despite the increasing use of the KD in weight loss and its appetite-reducing properties the behavioral evaluation of appetite regulation has not been addressed in preclinical studies. This review provides an overview of the behavioral effects of nutritional ketosis addressed to a broad audience of scientists interested in the KD field but not necessarily specializing in behavioral tests.

Protective Effect of Tertiary Butylhydroquinone against Obesity-induced Skeletal Muscle Pathology in Post-weaning High Fat Diet Fed Rats

BACKGROUND

Obesity deleteriously affects skeletal muscle functionality starting from infancy to adulthood, leading to dysfunctional skeletal muscle.

OBJECTIVES

This study, therefore, evaluated the protective action of tert-butylhydroquinone (tBHQ) against obesity-induced skeletal muscle pathology in high-fat diet (HFD) fed rats.

METHODS

Twenty post-weaning male albino rats were randomized into four groups of five rats each as: Group 1 (control), Group 2 (HFD), Group 3 (orlistat) and Group 4 (tBHQ). Group one received rat pellets for 12 weeks, while groups 2 to 4 received HFD for 12 weeks. At the end of week 8, obesity was confirmed with Lee Obesity Index and body mass index values of ≥ 303 and ≥ 0.68 gcm2, respectively. Group 3 was given oral administration of orlistat (10 mg/kg, once daily), while group 4 was given oral administration of tBHQ (25 mg/kg, once daily). Administration of orlistat and tBHQ commenced from week 9 to the end of the experiment.

RESULTS

Chronic exposure of post-weaning rats to HFD led to their development of the metabolic syndrome phenotypes in adulthood, characterized by obesity, hyperglycemia, dyslipidaemia, hyperinsulinaemia, insulin resistance as well as induction of oxidative stress and alteration of skeletal muscle markers, which were mitigated following supplementation with orlistat and tBHQ.

CONCLUSION

The study showed the anti-obesity potentials of tBHQ and its protective action against HFD obesity-induced skeletal muscular pathology.

An 8-week ketogenic diet improves exercise endurance and liver antioxidant capacity after weight loss in obese mice

Evolving evidence supports the role of the ketogenic diet (KD) in weight loss. However, no coherent conclusions are drawn on its impact on the effect of KD on exercise and antioxidant capacity after weight loss in obese individuals. We evaluated the exercise performance, energy metabolism and antioxidant capacity of mice after weight loss using high-fat diet-induced obese mice, and used KD and normal diet (ND) intervention, respectively, to provide a theoretical basis for further study of the health effects of KD. Our results showed that the 8-week KD significantly reduced the body weight of obese mice and improved the performance of treadmill exercise, but had no significant effect on grip strength. Serum biochemical results suggest that KD has the risk of elevating blood lipid. In liver tissue, KD significantly reduced the level of oxidative stress and increased the antioxidant capacity of the liver. Our findings suggest that the intervention with KD led to weight loss, modulate energy metabolism and improve aerobic exercise endurance in obese mice. Despite its antioxidant potential in the liver, the utilization of KD still requires caution. This study underscores the need for further investigation into the health impacts of KD, especially in regard to its potential risks.

Exogenous Ketone Supplementation and Ketogenic Diets for Exercise: Considering the Effect on Skeletal Muscle Metabolism

In recent years, ketogenic diets and ketone supplements have increased in popularity, particularly as a mechanism to improve exercise performance by modifying energetics. Since the skeletal muscle is a major metabolic and locomotory organ, it is important to take it into consideration when considering the effect of a dietary intervention, and the impact of physical activity on the body. The goal of this review is to summarize what is currently known and what still needs to be investigated concerning the relationship between ketone body metabolism and exercise, specifically in the skeletal muscle. Overall, it is clear that increased exposure to ketone bodies in combination with exercise can modify skeletal muscle metabolism, but whether this effect is beneficial or detrimental remains unclear and needs to be further interrogated before ketogenic diets or exogenous ketone supplementation can be recommended.

Neutrophil Depletion Attenuates Acute Liver Stress after Exhaustive Exercise in Mice

PURPOSE

Exhaustive exercise induces acute liver stress; however, the precise mechanisms remain unclear.

METHODS

We investigated the effects of neutrophil depletion in male C57BL/6J mice. Male C57BL/6J mice were divided into four groups: sedentary with control antibody ( n = 20), sedentary with antineutrophil antibody ( n = 20), exhaustive exercise with control antibody ( n = 20), and exhaustive exercise with antineutrophil antibody ( n = 20). Antineutrophil antibodies (1A8) or control antibodies were administered intraperitoneally before running on a treadmill. Immediately and at 24 h after running to exhaustion on a treadmill at a 7% gradient and a speed of 24 m·min -1 , blood neutrophil counts were measured by flow cytometry. Plasma activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were also measured. Hematoxylin-eosin staining was performed to calculate the liver stress score, and hepatic tumor necrosis factor-α was measured using enzyme-linked immunosorbent assay.

RESULTS

Exercise increased blood neutrophil and neutrophil infiltration into the liver. Plasma AST and ALT activities were significantly higher immediately after exhaustive exercise than after sedentary control (AST, sedentary with control antibody: 52.2 ± 0.4, exhaustive exercise with control antibody: 210.0 ± 19.8; ALT, sedentary with control antibody: 29.8 ± 2.2, exhaustive exercise with control antibody: 87.2 ± 15.8). However, AST and ALT activities were significantly decreased with the 1A8 antibody (AST, 102.2 ± 12.9; ALT, 39.2 ± 4.0). In addition, the liver stress score increased after exercise but was significantly reduced by prior 1A8 antibody administration. The 1A8 antibody treatment also decreased hepatic tumor necrosis factor-α levels after exhaustive exercise.

CONCLUSIONS

These results suggested that neutrophils play a critical role in increasing liver stress by regulating inflammation.

Cystine/Glutamine Mixture Supplementation Attenuated Fatigue during Endurance Exercise in Healthy Young Men by Enhancing Fatty Acid Utilization

Exercise-induced fatigue is a multi-origin physical and mental phenomenon. Efforts to diminish the above predisposition may contribute to endurance, along with athletic well-being, while development of nutritional strategies to optimize condition and exercise performance are essential issues for athletes and trainers. Dietary amino acids are being discussed for their specific health-promoting properties beyond their role as building blocks of proteins. Glutamine, along with cysteine, are two kinds of amino acids that are reported extensively for their anti-oxidation, anti-inflammation, and immune-regulation properties, and are promising in sport applications. In the present study, we designed a randomized, placebo-controlled, crossover trial to examine effects of 7-day supplementation of cystine/glutamine mixture (Cys2/Gln) on self-reporting fatigue index (ratings of perceived exertion, RPE), energy metabolism, and inflammation. We also employed a C2C12 myotube model to examine the capacity of cystine for fatty acid utilization. Cys2/Gln supplementation alleviated fatigue by decreasing RPE and enhanced fatty acid oxidation during a 60 min endurance exercise in human trials, while cystine increased fatty acid utilization in C2C12 myotubes by enhancing mitochondrial respiration. In summary, Cys2/Gln supplementation exerts positive effects on ameliorating exercise-induced fatigue, mechanisms of which can be attributed to enhancement of fatty acid utilization.

The effect of long-term ketogenic diet on serum adiponectin and insulin-like growth factor-1 levels in mice

OBJECTIVES

Noncommunicable disease (NCD) including obesity, cancer, and diabetes has become particular concern worldwide due to its morbidity and mortality which keep increasing annually. Adiponectin and insulin-like growth factor-1 (IGF-1) are known to be substances that are involved in the development of NCD. Several diet regimens have been developed to treat NCD, one of which is the ketogenic diet (KD). This study aimed to analyze the long-term KD effect on serum adiponectin and IGF-1 levels in mice.

METHODS

This study was a real experimental with post-test only controls group design. The subjects were 14 male mice (2-3 months, 20-30 g) were randomly divided into two groups, K1 (n=7, standard diet) and K2 (n=7, KD with a composition of 60% fat, 30% protein, and 10% fiber). All subjects were given diet intervention for 8 weeks ad libitum. Serum adiponectin and IGF levels were measured in post-intervention using Enzyme-Linked Immunosorbent Assay. Distribution of normality was analyzed by the Shapiro-Wilk Test, mean difference using Independent T-Test, and linear correlation using Pearson's Correlation Test. Data analysis was performed using Statistic Package for Social Science Version 16.

RESULTS

Serum adiponectin levels in K1 (0.080 ± 0.012) pg/mL and K2 (0.099 ± 0.005) pg/mL, with p=0.003. Serum IGF-1 levels in K1 (133.535 ± 25.702) ng/mL and K2 (109.987 ± 27.118) ng/mL, with p=0.121. Coefficient correlation between serum adiponectin and serum IGF-1 levels [r]=-0.401, with p=0.155.

CONCLUSIONS

Long-term KD increases serum adiponectin levels and has no effect on serum IGF-1 levels. There was no significant correlation between serum adiponectin and serum IGF-1 levels.

Isonitrogenous low-carbohydrate diet elicits specific changes in metabolic gene expression in the skeletal muscle of exercise-trained mice

With the renewed interest in low-carbohydrate diets (LCDs) in the sports field, a few animal studies have investigated their potential. However, most rodent studies have used an LCD containing low protein, which does not recapitulate a human LCD, and the muscle-specific adaptation in response to an LCD remains unclear. Therefore, we investigated the effects of two types of LCDs, both containing the same proportion of protein as a regular diet (isonitrogenous LCD; INLCD), on body composition, exercise performance, and metabolic fuel selection at the genetic level in the skeletal muscles of exercise-trained mice. Three groups of mice (n = 8 in each group), one fed a regular AIN-93G diet served as the control, and the others fed either of the two INLCDs containing 20% protein and 10% carbohydrate (INLCD-10%) or 20% protein and 1% carbohydrate (INLCD-1%) had a regular exercise load (5 times/week) for 12 weeks. Body weight and muscle mass did not decrease in either of the INLCD-fed groups, and the muscle glycogen levels and endurance capacity did not differ among the three groups. Only in the mice fed INLCD-1% did the plasma ketone concentration significantly increase, and gene expression related to glucose utilization significantly declined in the muscles. Both INLCD-1% and INLCD-10% consumption increased gene expression related to lipid utilization. These results suggest that, although INLCD treatment did not affect endurance capacity, it helped maintain muscle mass and glycogen content regardless of the glucose intake restrictions in trained mice. Moreover, an INLCD containing a low carbohydrate content might present an advantage by increasing lipid oxidation without ketosis and suppressing muscle glucose utilization.

The Gut Microbiome in Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS)

Myalgic encephalomyelitis (ME) or Chronic Fatigue Syndrome (CFS) is a neglected, debilitating multi-systemic disease without diagnostic marker or therapy. Despite evidence for neurological, immunological, infectious, muscular and endocrine pathophysiological abnormalities, the etiology and a clear pathophysiology remains unclear. The gut microbiome gained much attention in the last decade with manifold implications in health and disease. Here we review the current state of knowledge on the interplay between ME/CFS and the microbiome, to identify potential diagnostic or interventional approaches, and propose areas where further research is needed. We iteratively selected and elaborated on key theories about a correlation between microbiome state and ME/CFS pathology, developing further hypotheses. Based on the literature we hypothesize that antibiotic use throughout life favours an intestinal microbiota composition which might be a risk factor for ME/CFS. Main proposed pathomechanisms include gut dysbiosis, altered gut-brain axis activity, increased gut permeability with concomitant bacterial translocation and reduced levels of short-chain-fatty acids, D-lactic acidosis, an abnormal tryptophan metabolism and low activity of the kynurenine pathway. We review options for microbiome manipulation in ME/CFS patients including probiotic and dietary interventions as well as fecal microbiota transplantations. Beyond increasing gut permeability and bacterial translocation, specific dysbiosis may modify fermentation products, affecting peripheral mitochondria. Considering the gut-brain axis we strongly suspect that the microbiome may contribute to neurocognitive impairments of ME/CFS patients. Further larger studies are needed, above all to clarify whether D-lactic acidosis and early-life antibiotic use may be part of ME/CFS etiology and what role changes in the tryptophan metabolism might play. An association between the gut microbiome and the disease ME/CFS is plausible. As causality remains unclear, we recommend longitudinal studies. Activity levels, bedridden hours and disease progression should be compared to antibiotic exposure, drug intakes and alterations in the composition of the microbiota. The therapeutic potential of fecal microbiota transfer and of targeted dietary interventions should be systematically evaluated.

A combination of ketogenic diet and voluntary exercise ameliorates anxiety and depression-like behaviors in Balb/c mice

The positive effects of both ketogenic diet (KD) and regular voluntary exercise on anxiety and depression behavior have been recently reported in rodent animals, but the effects of pairing a KD with exercise on depression and anxiety are unknown. In this study, we aimed to investigate the effects of combination of KD and regular voluntary exercise on anxiety and depression-like behavior in Balb/c mice. We've demostrated that anxiety and depression levels decreased in KD-exercised (KD-Ex) mice. β-hydroxybutyrate (BHB) levels increased while glucose, insulin levels and LDL/HDL ratio decreased in KD-Ex mice. There was a negative correlation between BHB and the time spent in the closed arms of elevated plus maze (EPM) or the time spent in periphery walls of open field test (OFT) and the immobility time in forced swim test (FST) which all of them are indicators of low depression and anxiety levels. There was a positive correlation between LDL/HDL ratio and the time spent in the closed arms of EPM or the immobility time in FST. The immobility time in FST was positively correlated with insulin while the mobility time in FST was negatively correlated with glucose. In conclusion, these results suggest that decline in anxiety and depression-like behaviors resulted from KD with regular voluntary exercise may be associated with increased BHB levels and decreased LDL/HDL ratio and insulin or glucose levels. Further research is necessary for our understanding of the mechanisms by which pairing a KD with voluntary exercise influences brain and behavior.

Recent Progress in Applicability of Exercise Immunology and Inflammation Research to Sports Nutrition

This article focuses on how nutrition may help prevent and/or assist with recovery from the harmful effects of strenuous acute exercise and physical training (decreased immunity, organ injury, inflammation, oxidative stress, and fatigue), with a focus on nutritional supplements. First, the effects of ketogenic diets on metabolism and inflammation are considered. Second, the effects of various supplements on immune function are discussed, including antioxidant defense modulators (vitamin C, sulforaphane, taheebo), and inflammation reducers (colostrum and hyperimmunized milk). Third, how 3-hydroxy-3-methyl butyrate monohydrate (HMB) may offset muscle damage is reviewed. Fourth and finally, the relationship between exercise, nutrition and COVID-19 infection is briefly mentioned. While additional verification of the safety and efficacy of these supplements is still necessary, current evidence suggests that these supplements have potential applications for health promotion and disease prevention among athletes and more diverse populations.

The Effects of Fasting or Ketogenic Diet on Endurance Exercise Performance and Metabolism in Female Mice

The promotion of ketone body (KB) metabolism via ketosis has been suggested as a strategy to increase exercise performance. However, studies in humans and animals have yielded inconsistent results. The purpose of the current study was to examine the effects of ketosis, achieved via fasting or a short-term ketogenic diet (KD), on endurance exercise performance in female mice. After 8 h of fasting, serum KB significantly increased and serum glucose significantly decreased in fasted compared to fed mice. When subjected to an endurance exercise capacity (EEC) test on a motorized treadmill, both fed and fasted mice showed similar EEC performance. A 5-week KD (90% calories from fat) significantly increased serum KB but did not increase EEC times compared to chow-fed mice. KD mice gained significantly more weight than chow-fed mice and had greater adipose tissue mass. Biochemical tissue analysis showed that KD led to significant increases in triglyceride content in the heart and liver and significant decreases in glycogen content in the muscle and liver. Furthermore, KD downregulated genes involved in glucose and KB oxidation and upregulated genes involved in lipid metabolism in the heart. These findings suggest that a short-term KD is not an effective strategy to enhance exercise performance and may lead to increased adiposity, abnormal endogenous tissue storage, and cardiometabolic remodeling.

Combined effects of a ketogenic diet and exercise training alter mitochondrial and peroxisomal substrate oxidative capacity in skeletal muscle

Ketogenic diets (KDs) are reported to improve body weight, fat mass, and exercise performance in humans. Unfortunately, most rodent studies have used a low-protein KD, which does not recapitulate diets used by humans. Since skeletal muscle plays a critical role in responding to macronutrient perturbations induced by diet and exercise, the purpose of this study was to test if a normal-protein KD (NPKD) impacts shifts in skeletal muscle substrate oxidative capacity in response to exercise training (ExTr). A high fat, carbohydrate-deficient NPKD (16.1% protein, 83.9% fat, 0% carbohydrate) was given to C57BL/6J male mice for 6 wk, whereas controls (Con) received a low-fat diet with similar protein (15.9% protein, 11.9% fat, 72.2% carbohydrate). After 3 wk on the diet, mice began treadmill training 5 days/wk, 60 min/day for 3 wks. The NPKD increased body weight and fat mass, whereas ExTr negated a continued rise in adiposity. ExTr increased intramuscular glycogen, whereas the NPKD increased intramuscular triglycerides. Neither the NPKD nor ExTr alone altered mitochondrial content; however, in combination, the NPKD-ExTr group showed increases in PGC-1α and markers of mitochondrial fission/fusion. Pyruvate oxidative capacity was unchanged by either intervention, whereas ExTr increased leucine oxidation in NPKD-fed mice. Lipid metabolism pathways had the most notable changes as the NPKD and ExTr interventions both enhanced mitochondrial and peroxisomal lipid oxidation and many adaptations were additive or synergistic. Overall, these results suggest that a combination of a NPKD and ExTr induces additive and/or synergistic adaptations in skeletal muscle oxidative capacity.NEW & NOTEWORTHY A ketogenic diet with normal protein content (NPKD) increases body weight and fat mass, increases intramuscular triglyceride storage, and upregulates pathways related to protein metabolism. In combination with exercise training, a NPKD induces additive and/or synergistic activation of AMPK, PGC-1α, mitochondrial fission/fusion genes, mitochondrial fatty acid oxidation, and peroxisomal adaptations in skeletal muscle. Collectively, results from this study provide mechanistic insight into adaptations in skeletal muscle relevant to keto-adaptation.

A Low-Protein High-Fat Diet Leads to Loss of Body Weight and White Adipose Tissue Weight via Enhancing Energy Expenditure in Mice

Obesity has become a worldwide health problem over the past three decades. During obesity, metabolic dysfunction of white adipose tissue (WAT) is a key factor increasing the risk of type 2 diabetes. A variety of diet approaches have been proposed for the prevention and treatment of obesity. The low-protein high-fat diet (LPHF) is a special kind of high-fat diet, characterized by the intake of a low amount of protein, while compared to typical high-fat diet, may induce weight loss and browning of WAT. Physical activity is another effective intervention to treat obesity by reducing WAT mass, inducing browning of WAT. In order to determine whether an LPHF, along with exercise enhanced body weight loss and body fat loss as well as the synergistic effect of an LPHF and exercise on energy expenditure in a mice model, we combined a 10-week LPHF with an 8-week forced treadmill training. Meanwhile, a traditional high-fat diet (HPHF) containing the same fat and relatively more protein was introduced as a comparison. In the current study, we further analyzed energy metabolism-related gene expression, plasma biomarkers, and related physiological changes. When comparing to HPHF, which induced a dramatic increase in body weight and WAT weight, the LPHF led to considerable loss of body weight and WAT, without muscle mass and strength decline, while it exhibited a risk of liver and pancreas damage. The mechanism underlying the LPHF-induced loss of body weight and WAT may be attributed to the synergistically upregulated expression of Ucp1 in WAT and Fgf21 in the liver, which may enhance energy expenditure. The 8-week training did not further enhance weight loss and increased plasma biomarkers of muscle damage when combined with LPHF. Furthermore, LPHF reduced the expression of fatty acid oxidation-related genes in adipose tissues, muscle tissues, and liver. Our results indicated that an LPHF has potential for obesity treatment, while the physiological condition should be monitored during application.

A Low-Carbohydrate Ketogenic Diet and Treadmill Training Enhanced Fatty Acid Oxidation Capacity but Did Not Enhance Maximal Exercise Capacity in Mice

The low-carbohydrate ketogenic diet (LCKD) is a dietary approach characterized by the intake of high amounts of fat, a balanced amount of protein, and low carbohydrates, which is insufficient for metabolic demands. Previous studies have shown that an LCKD alone may contribute to fatty acid oxidation capacity, along with endurance. In the present study, we combined a 10-week LCKD with an 8-week forced treadmill running program to determine whether training in conjunction with LCKD enhanced fatty acid oxidation capacity, as well as whether the maximal exercise capacity would be affected by an LCKD or training in a mice model. We found that the lipid pool and fatty acid oxidation capacity were both enhanced following the 10-week LCKD. Further, key fatty acid oxidation related genes were upregulated. In contrast, the 8-week training regimen had no effect on fatty acid and ketone body oxidation. Key genes involved in carbohydrate utilization were downregulated in the LCKD groups. However, the improved fatty acid oxidation capacity did not translate into an enhanced maximal exercise capacity. In summary, while favoring the fatty acid oxidation system, an LCKD, alone or combined with training, had no beneficial effects in our intensive exercise-evaluation model. Therefore, an LCKD may be promising to improve endurance in low- to moderate-intensity exercise, and may not be an optimal choice for those partaking in high-intensity exercise.

Ketones for Post-exercise Recovery: Potential Applications and Mechanisms

Ketogenic diet has been introduced in therapeutic areas for more than a century, but the role of ketones in exercise performance has only been explored in the past decade. One of the main reasons that allows the investigation of the role of ketones in exercise performance is the emergence of exogenous ketones, allowing athletes to achieve the state of ketosis acutely, and independent of their metabolic states. While there are mixed results showing either exogenous ketones improve exercise performance or no effect, the mechanisms of action are still being heavily researched. Moreover, these early data from exercise physiology studies suggested that exogenous ketones may play a more prominent role in post-exercise recovery, leading to a more pronounced cumulative impact over subsequent exercise performance. This review will look at existing evidence on the role of ketones in recovery and attempt to identify the current best practices and potential mechanisms that drive improved recovery.

Comparison of murine behavioural and physiological responses after forced exercise by electrical shock versus manual prodding

NEW FINDINGS

What is the central question of this study? Forced treadmill exercise using electrical shock is the most common technique in rodent exercise studies. Here, we examined how the use of electrical shock during forced treadmill exercise affects behavioural and physiological responses in comparison to a novel non-electrical shock technique. What is the main finding and its importance? In comparison to mice that underwent traditional treadmill running induced by electrical shock, mice that underwent forced running using a novel technique involving gentle prodding to induce running showed: (i) higher locomotor activity; (ii) less anxiety-like behaviour; and (iii) altered exercise-induced muscle pain immediately after exercise.

ABSTRACT

Animal models of exercise have been useful to understand underlying cellular and molecular mechanisms. Many studies have used methods of exercise that are unduly stressful (e.g., electrical shock to force running), potentially skewing results. Here, we compared physiological and behavioural responses of mice after exercise induced using a prodding technique that avoids electrical shock versus a traditional protocol using electrical shock. We found that exercise performance was similar for both techniques; however, the shock group demonstrated significantly lower locomotor activity and higher anxiety-like behaviour. We also observed divergent effects on muscle pain; the prodding group showed hyperalgesia immediately after exercise, whereas the shock group showed hypoalgesia. Corticosterone concentrations were elevated to a similar extent for both groups. In conclusion, mice that were exercised without shock generated similar maximal exercise performance, but postexercise these mice showed an increase in locomotor activity, less anxiety-like behaviour and altered muscle pain in comparison to mice that exercised with shock. Our data suggest that running of mice without the use of electrical shock is potentially less stressful and might be a better technique to study the physiological and behavioural responses to exercise.

Ketone Monoester Supplementation Does Not Expedite the Recovery of Indices of Muscle Damage After Eccentric Exercise

Purpose: The purpose of this study was to evaluate the effects of a ketone monoester supplement on indices of muscle damage during recovery after eccentric exercise.

Methods: In a randomized, double-blind, independent group design, 20 moderately active healthy young adults consumed 360 mg per kg⁻¹ bodyweight of a ketone monoester (KET) or energy-matched carbohydrate (CON) supplement twice daily following eccentric exercise (drop jumps). Maximal isometric voluntary contraction (MIVC) torque, counter-movement jump (CMJ) height, and muscle soreness were measured before (PRE), and immediately (POST), 24 h and 48 h post-exercise. Blood samples were collected for analysis of β-hydroxybutyrate (β-OHB), creatine kinase (CK), and select pro- and anti-inflammatory cytokines.

Results: Peak blood β-OHB concentration after supplement intake was greater (P < 0.001) in KET (4.4 ± 0.8 mM) vs. CON (0.4 ± 0.3 mM). Exercise increased CK concentration at 24 h and 48 h vs. PRE (time: P < 0.001) with no difference between KET and CON. Exercise reduced MIVC (KET: −19.9 ± 14.6; CON: −22.6 ± 11.1%) and CMJ (KET: −11.0 ± 7.5; CON: −13.0 ± 8.7%) at POST relative PRE; however, there was no difference between KET and CON on the recovery of MIVC at 24 h (KET: −15.4 ± 20.4; CON: −18.7 ± 20.1%) or 48 h (KET: −7.2 ± 21.2; CON: −11.8 ± 20.2%), or CMJ at 24 h (KET: −9.2 ± 11.5; CON: −13.4 ± 10.8) or 48 h (KET: −12.5 ± 12.4; CON: −9.1 ± 11.7). Muscle soreness was increased during post-exercise recovery (time: P < 0.001) with no differences between KET and CON. Monocyte chemoattractant protein-1 was greater (group: P = 0.007) in CON (236 ± 11 pg/mL) vs. KET (187 ± 11 pg/mL).

Conclusion: In conclusion, twice daily ingestion of a ketone monoester supplement that acutely elevates blood β-OHB concentration does not enhance the recovery of muscle performance or reduce muscle soreness following eccentric exercise in moderately active, healthy young adults.

Are ketogenic diets promising for Alzheimer's disease? A translational review

Background

Brain amyloid deposition and neurofibrillary tangles in Alzheimer’s disease (AD) are associated with complex neuroinflammatory reactions such as microglial activation and cytokine production. Glucose metabolism is closely related to neuroinflammation. Ketogenic diets (KDs) include a high amount of fat, low carbohydrate and medium-chain triglyceride (MCT) intake. KDs lead to the production of ketone bodies to fuel the brain, in the absence of glucose. These nutritional interventions are validated treatments of pharmacoresistant epilepsy, consequently leading to a better intellectual development in epileptic children. In neurodegenerative diseases and cognitive decline, potential benefits of KD were previously pointed out, but the published evidence remains scarce. The main objective of this review was to critically examine the evidence regarding KD or MCT intake effects both in AD and ageing animal models and in humans.

Main body

We conducted a review based on a systematic search of interventional trials published from January 2000 to March 2019 found on MEDLINE and Cochrane databases. Overall, 11 animal and 11 human studies were included in the present review. In preclinical studies, this review revealed an improvement of cognition and motor function in AD mouse model and ageing animals. However, the KD and ketone supplementation were also associated with significant weight loss. In human studies, most of the published articles showed a significant improvement of cognitive outcomes (global cognition, memory and executive functions) with ketone supplementation or KD, regardless of the severity of cognitive impairments previously detected. Both interventions seemed acceptable and efficient to achieve ketosis.

Conclusion

The KD or MCT intake might be promising ways to alter cognitive symptoms in AD, especially at the prodromal stage of the disease. The need for efficient disease-modifying strategies suggests to pursue further KD interventional studies to assess the efficacy, the adherence to this diet and the potential adverse effects of these nutritional approaches.

Ergogenic Properties of Ketogenic Diets in Normal-Weight Individuals: A Systematic Review

Ketogenic diets (KDs) have received increasing attention among athletes and physically active individuals. However, the question as to whether and how the diet could benefit this healthy cohort remains unclear.Purpose: This study was designed to systematically review the existing evidence concerning the effect of KDs on body composition, aerobic and anaerobic capacity, muscle development, and sports performance in normal-weight individuals including athletes.Methods: A systematic search of English literature was conducted through electronic databases including PubMed, EBSCOhost, and Google Scholar. Upon the use of search criteria, 23 full-text original human studies involving non-obese participants were included in this review. For more stratified and focused analysis, these articles were further categorized based on the outcomes being examined including 1) body mass (BM) and %fat, 2) substrate utilization, 3) blood substrate and hormonal responses, 4) aerobic capacity and endurance performance, and 5) strength, power, and anaerobic capacity.Results: Our review indicates that a non-calorie-restricted KD carried out for ≥3 weeks can produce a modest reduction in BM and %fat, while maintaining fat-free mass. This diet leads to augmented use of fat as fuel, but this adaptation doesn't seem to improve endurance performance. Additionally, ad libitum KDs combined with resistance training will pose no harm to developing strength and power, especially when protein intake is increased modestly.Conclusions: It appears that a non-calorie-restricted KD provides minimal ergogenic benefits in normal-weight individuals including athletes, but can be used for optimizing BM and body composition without compromising aerobic and anaerobic performance. Key teaching pointsKetogenic diets have received increasing attention among athletes and physically active individuals.It remains elusive as to whether ketogenic diets could confer ergogenic benefits for those who are normal weight but want to use the diet to improve fitness and performance.An interesting dilemma exists in that ketogenic diets can reduce body mass and %fat and increase fat oxidation, but they can also decrease glycogen stores and limit sports performance.This review concludes that a non-calorie-restricted ketogenic diet provides minimal ergogenic benefits in normal-weight individuals, but can be used to optimize body mass and composition without compromising athletic performance.This finding can be important for esthetic or weight-sensitive athletes because the diet may allow them to reach a target body mass without having to sacrifice athletic performance.The ketogenic diet-induced metabolic adaptations require a state of ketosis, and thus caution should be taken because an excessive increase in ketone bodies can be detrimental to health.

Protective Effects of Sulforaphane on Exercise-Induced Organ Damage via Inducing Antioxidant Defense Responses

Regular exercise is beneficial to maintain a healthy lifestyle, but the beneficial effects are lost in the case of acute exhaustive exercise; this causes significant inflammation, oxidative stress along with organ damage. Recently, sulforaphane (SFN), an indirect antioxidant, has drawn special attention for its potential protective effect against inflammation and oxidative stress. However, no studies have been performed regarding acute exhaustive exercise-induced organ damage in association with SFN administration. Therefore, the aim of this study was to investigate the effects of SFN on acute exhaustive exercise-induced organ damage and the mechanisms involved. To perform the study, we divided mice into four groups: Control, SFN, exercise, and SFN plus exercise. The SFN group was administered orally (50 mg/kg body wt) 2 h before the running test. We measured plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH), and acute exhaustive exercise significantly increased these biomarkers. In addition, the mRNA expression of pro-inflammatory cytokines, IL-6, IL-1β, and TNF-α, were significantly increased in the liver of exercise group. However, the SFN plus exercise group showed a significant reduction in the expression of cytokines and blood biomarkers of tissue damage or cell death. Furthermore, we measured mRNA expression of Nrf2, heme oxygenase (HO)-1, and antioxidant defense enzymes expression, i.e., superoxide dismutase (SOD1), catalase (CAT), and glutathione peroxidase (GPx1) in the liver. The expression of all these biomarkers was significantly upregulated in the SFN plus exercise group. Collectively, SFN may protect the liver from exhaustive exercise-induced inflammation via inducing antioxidant defense response through the activation of Nrf2/HO-1 signal transduction pathway.

Ketogenic diets and protective mechanisms in epilepsy, metabolic disorders, cancer, neuronal loss, and muscle and nerve degeneration

Ketogenic diet (KD), the "High-fat, low-carbohydrate, adequate-protein" diet strategy, replacing glucose with ketone bodies, is effective against several diseases, from intractable epileptic seizures, metabolic disorders, tumors, autosomal dominant polycystic kidney disease, and neurodegeneration to skeletal muscle atrophy and peripheral neuropathy. Key mechanisms include augmented mitochondrial efficiency, reduced oxidative stress, and regulated phospho-AMP-activated protein kinase, gamma-aminobutyric acid-glutamate, Na^+/ K⁺ pump, leptin and adiponectin levels, ghrelin levels, lipogenesis, ketogenesis, lipolysis, and gluconeogenesis. In cancer cells, KD targets glucose metabolism, suppresses insulin-like growth factor-1 and PI3K/AKT/mTOR pathways, and reduces cancer cachexia and muscle waste and fatigue. An associated increased skeletal proliferator-activated receptor-γ coactivator-1α activity alters systemic ketone body homeostasis, contributing toward attenuated diabetic hyperketonemia. Antioxidative and anti-inflammatory properties enable KD enhance endurance and sports performances while preventing exercise-induced muscle and organ debility. KD reduces metabolic syndromes-associated allodynia and promotes peripheral axonal and sensory regeneration. This review enlightens effects of KD on various disease conditions. PRACTICAL APPLICATIONS: It is increasingly being realized that diet plays a very important role in our fight against several diseases. This can range from neurological disorders to diabetes and cancer. In this context, the potential of KD, the "High-fat, low-carbohydrate, adequate-protein" diet strategy, is increasingly being realized. In this article, we provide a comprehensive analysis of the benefits of KD against many diseases and discuss the underlying biochemical mechanisms. We hope that our write-up will stimulate further research on KD and help generate an interest for the populations to adopt this healthy diet. It can help overcome the problems associated with weight and dysregulated metabolism.

Ketogenic Diets and Exercise Performance

The ketogenic diet (KD) has gained a resurgence in popularity due to its purported reputation for fighting obesity. The KD has also acquired attention as an alternative and/or supplemental method for producing energy in the form of ketone bodies. Recent scientific evidence highlights the KD as a promising strategy to treat obesity, diabetes, and cardiac dysfunction. In addition, studies support ketone body supplements as a potential method to induce ketosis and supply sustainable fuel sources to promote exercise performance. Despite the acceptance in the mainstream media, the KD remains controversial in the medical and scientific communities. Research suggests that the KD or ketone body supplementation may result in unexpected side effects, including altered blood lipid profiles, abnormal glucose homeostasis, increased adiposity, fatigue, and gastrointestinal distress. The purpose of this review article is to provide an overview of ketone body metabolism and a background on the KD and ketone body supplements in the context of obesity and exercise performance. The effectiveness of these dietary or supplementation strategies as a therapy for weight loss or as an ergogenic aid will be discussed. In addition, the recent evidence that indicates ketone body metabolism is a potential target for cardiac dysfunction will be reviewed.

Chronic Inflammation as an Immunological Abnormality and Effectiveness of Exercise

Reduced levels of physical activity in people’s daily lives cause the development of metabolic syndromes or age-related disorders. Chronic inflammation is now understood to be an underlying pathological condition in which inflammatory cells such as neutrophils and monocyte/macrophages infiltrate into fat and other tissues and accumulate when people become obese due to overeating and/or physical inactivity. Pro-inflammatory mediators such as cytokines that are secreted in excess from inflammatory cells will not only lead to the development of arteriosclerosis when they chronically affect blood vessels but also bring tissue degeneration and/or dysfunction to various organs. Chronic inflammation is also involved in sarcopenia that brings hypofunction in the elderly, dementia, osteoporosis, or cancer and negatively affects many chronic diseases and people’s healthy life expectancy. In this paper, outlines of such studies are introduced in terms of homeostatic inflammation, which occurs chronically due to the innate immune system and its abnormalities, while focusing on the efficacy of exercise from aspects of immunology and oxidative stress. The preventative effects of functional food ingredients in combination with exercise are also introduced and described. The challenges and future directions in understanding the role of exercise in the control of chronic inflammation are discussed.

Keto-Adaptation and Endurance Exercise Capacity, Fatigue Recovery, and Exercise-Induced Muscle and Organ Damage Prevention: A Narrative Review

A ketogenic diet (KD) could induce nutritional ketosis. Over time, the body will acclimate to use ketone bodies as a primary fuel to achieve keto-adaptation. Keto-adaptation may provide a consistent and fast energy supply, thus improving exercise performance and capacity. With its anti-inflammatory and anti-oxidative properties, a KD may contribute to muscle health, thus preventing exercise-induced fatigue and damage. Given the solid basis of its potential to improve exercise capacity, numerous investigations into KD and exercise have been carried out in recent years. This narrative review aims to summarize recent research about the potential of a KD as a nutritional approach during endurance exercise, focusing on endurance capacity, recovery from fatigue, and the prevention of exhaustive exercise-induced muscle and organ damage.

An 8-Week Ketogenic Diet Alternated Interleukin-6, Ketolytic and Lipolytic Gene Expression, and Enhanced Exercise Capacity in Mice

Adjusting dietary fat intake is reported to affect mitochondrial biogenesis and fatty acid oxidation (FAO), and thus may enhance exercise capacity. However, a high-fat diet where carbohydrate intake is not limited enough also makes it difficult for athletes to maintain weight, and may fail to force the body to utilize fat. As such, a low-carbohydrate, high-fat, ketogenic diet (KD) may be viable. We have previously reported that an eight-week KD enhances exercise capacity, and suggested the mechanism to be enhanced lipolysis and ketolysis. In the present study, we investigated how an eight-week KD alters mRNA expression during fatty acid mobilization, FAO and ketolysis. We found that an eight-week KD may remodel the lipid metabolism profile, thus contributing to influence exercise capacity. We also found that ketolysis, lipolysis and FAO adaptations may contribute to enhanced exhaustive exercise performance. Along with enhanced FAO capacity during exhaustive exercise, a KD may also alter IL-6 synthesis and secretion profile, thus contribute to fatty acid mobilization, ketolysis, lipolysis and preventing muscle damage. Both the lipid metabolism response and IL-6 secretion appeared to be muscle fiber specific. Taken together, the previous and present results reveal that an eight-week KD may enhance exercise performance by up-regulating ketolysis and FAO ability. Therefore, a KD may have the potential to prevent muscle damage by altering IL-6 secretion profile, indicating that a KD may be a promising dietary approach in endurance athletes, sports, and for injury prevention.