Metabolic and hormonal responses to isoenergetic high-intensity interval exercise and continuous moderate-intensity exercise

Response of Blood Biomarkers to Sprint Interval Swimming

PURPOSE

To evaluate and compare the effects of 2 sprint interval training (SIT) sets of different distances on biochemical markers indicative of metabolism, stress, and antioxidant capacity in competitive swimmers and, to investigate the potential influence of gender on these markers.

METHODS

Twenty-four adolescent, well-trained swimmers (12 men and 12 women) participated in the study. In a random and counterbalanced order, the swimmers completed 2 SIT sets (8 × 50 m and 8 × 25 m) in freestyle with maximal intensity on different days. Work-to-rest ratio was 1:1 in both sets. Blood samples were drawn preexercise, immediately postexercise, and 1 hour postexercise to evaluate the effects of the SIT sets on a number of biochemical parameters.

RESULTS

Swimming speed was higher at 8 × 25 m. The 2 SIT sets induced significant increases in lactate, glucose, insulin, glucagon, cortisol, and uric acid (P ≤ .001). No differences in these parameters were found between sets, except for irisin (higher in 8 × 50 m; P = .02). Male swimmers were faster and had higher lactate and uric acid concentrations, as well as lower reduced glutathione concentration, than female swimmers (P < .01).

CONCLUSIONS

The 2 swimming SIT sets induced increases in most of the biochemical markers studied. The 2-fold difference between sets in distance did not differentiate the effects of sprint interval exercise on most biochemical parameters. Thus, low-volume SIT sets seem to be effective stimuli for competitive swimmers.

Trans-omic Analysis Reveals ROS-Dependent Pentose Phosphate Pathway Activation after High-Frequency Electrical Stimulation in C2C12 Myotubes

Skeletal muscle adaptation is mediated by cooperative regulation of metabolism, signal transduction, and gene expression. However, the global regulatory mechanism remains unclear. To address this issue, we performed electrical pulse stimulation (EPS) in differentiated C2C12 myotubes at low and high frequency, carried out metabolome and transcriptome analyses, and investigated phosphorylation status of signaling molecules. EPS triggered extensive and specific changes in metabolites, signaling phosphorylation, and gene expression during and after EPS in a frequency-dependent manner. We constructed trans-omic network by integrating these data and found selective activation of the pentose phosphate pathway including metabolites, upstream signaling molecules, and gene expression of metabolic enzymes after high-frequency EPS. We experimentally validated that activation of these molecules after high-frequency EPS was dependent on reactive oxygen species (ROS). Thus, the trans-omic analysis revealed ROS-dependent activation in signal transduction, metabolome, and transcriptome after high-frequency EPS in C2C12 myotubes, shedding light on possible mechanisms of muscle adaptation.

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We performed electrical pulse stimulation in differentiated C2C12 myotubes

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We constructed trans-omic network after high-frequency electrical pulse stimulation

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Trans-omic network integrates metabolome, transcriptome, and signaling molecules

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We identified ROS-dependent pentose phosphate pathway activation

Impact of a weight loss and fitness intervention on exercise-associated plasma oxylipin patterns in obese, insulin-resistant, sedentary women

Very little is known about how metabolic health status, insulin resistance or metabolic challenges modulate the endocannabinoid (eCB) or polyunsaturated fatty acid (PUFA)-derived oxylipin (OxL) lipid classes. To address these questions, plasma eCB and OxL concentrations were determined at rest, 10 and 20 min during an acute exercise bout (30 min total, ~45% of preintervention V̇O2peak , ~63 W), and following 20 min recovery in overnight-fasted sedentary, obese, insulin-resistant women under controlled diet conditions. We hypothesized that increased fitness and insulin sensitivity following a ~14-week training and weight loss intervention would lead to significant changes in lipid signatures using an identical acute exercise protocol to preintervention. In the first 10 min of exercise, concentrations of a suite of OxL diols and hydroxyeicosatetraenoic acid (HETE) metabolites dropped significantly. There was no increase in 12,13-DiHOME, previously reported to increase with exercise and proposed to activate muscle fatty acid uptake and tissue metabolism. Following weight loss intervention, exercise-associated reductions were more pronounced for several linoleate and alpha-linolenate metabolites including DiHOMEs, DiHODEs, KODEs, and EpODEs, and fasting concentrations of 9,10-DiHODE, 12,13-DiHODE, and 9,10-DiHOME were reduced. These findings suggest that improved metabolic health modifies soluble epoxide hydrolase, cytochrome P450 epoxygenase (CYP), and lipoxygenase (LOX) systems. Acute exercise led to reductions for most eCB metabolites, with no evidence for concentration increases even at recovery. It is proposed that during submaximal aerobic exercise, nonoxidative fates of long-chain saturated, monounsaturated, and PUFAs are attenuated in tissues that are important contributors to the blood OxL and eCB pools.

The roles of microRNA in redox metabolism and exercise-mediated adaptation

MicroRNAs (miRs) are small regulatory RNA transcripts capable of post-transcriptional silencing of mRNA messages by entering a cellular bimolecular apparatus called RNA-induced silencing complex. miRs are involved in the regulation of cellular processes producing, eliminating or repairing the damage caused by reactive oxygen species, and they are active players in redox homeostasis. Increased mitochondrial biogenesis, function and hypertrophy of skeletal muscle are important adaptive responses to regular exercise. In the present review, we highlight some of the redox-sensitive regulatory roles of miRs.

Metabolic load comparison between the quarters of a game in elite male basketball players using sport metabolomics

Purpose: A basketball match is characterized by intermittent high-intensity activities, thereby relying extensively on both aerobic and anaerobic metabolic pathways. Here, we aimed to compare the metabolic fluctuations between the four 10-min quarters of high-level basketball games using metabolomics analyses. Methods: 70 male basketball players with at least 3 years of experience in the Iran national top-league participated. Before and after each quarter, saliva samples were taken for subsequent untargeted metabolomics analyses, where Principal component analysis (PCA) and Partial least squares-discriminant analysis (PLS-DA) were employed for statistical analysis. Results: Quarters 1 and 3 showed similar metabolic profiles, with increased levels of ATP turnover (higher Lactate, Pyruvate, Succinic Acid, Citric Cid, Glucose and Hypoxanthine), indicating more reliance on anaerobic energy systems than quarters 2 and 4. In comparison, quarters 2 and 4 showed a reduction in Valine and Lucien and an increase in Alanine, Glycerol, AcetoAcetic Acid, Acetone, Succinic Acid, Citric Acid, Acetate and Taurine that was not present in quarters 1 and 3, indicating greater reliance of aerobic energy contribution, fat metabolism and gluconeogenesis. Conclusion: Our data demonstrate that the higher intensity of movements in the first quarter, where players are more rested, induce an increase in anaerobic energy contribution. This seems to be the case also for the third quarter that follows 15 min of rest, whereas the accumulated fatigue and reduction of high-intensity movements in the second and fourth quarters also reduces the speed of energy production and players thereby utilize more aerobic energy.

Metabolomics, physical activity, exercise and health: A review of the current evidence

Physical activity (PA) and exercise are among the most important determinants of health. However, PA is a complex and heterogeneous behavior and the biological mechanisms through which it impacts individuals and populations in different ways are not well understood. Genetics and environment likely play pivotal roles but further work is needed to understand their relative contributions and how they may be mediated. Metabolomics offers a promising approach to explore these relationships. In this review, we provide a comprehensive appraisal of the PA-metabolomics literature to date. This overwhelmingly supports the hypothesis of a metabolomic response to PA, which can differ between groups and individuals. It also suggests a biological gradient in this response based on PA intensity, with some evidence for global longer-term changes in the metabolome of highly active individuals. However, many questions remain and we conclude by highlighting future critical research avenues to help elucidate the role of PA in the maintenance of health and the development of disease.

Altered metabolic and hormonal responses to moderate exercise in overweight/obesity

BACKGROUND

An adequate metabolic and hormonal response to the switch from rest to exercise is critical for the health benefits of exercise interventions. Previous work suggests that this response is impaired with overweight/obesity but the specific differences between overweight/obese and lean individuals remain unclear.

METHODS

We compared glucose and non-esterified fatty acid (NEFA) regulation and the changes of key homeostatic hormones during 45 min of moderate exercise between 17 overweight/obese and 28 lean premenopausal women. For this comparison, we implemented an exercise protocol at 60% of individual peak oxygen uptake, with frequent blood sampling and under fasting conditions.

RESULTS

We found that at the same exercise intensity in the overweight/obese and the lean group of women, the metabolic and hormonal response differed. In contrast to the lean group, the overweight/obese group portrayed an activation in the stress axis (adrenocorticotropic hormone (ACTH)/cortisol) and a lower growth hormone (hGH) response and exercise-increase of plasma NEFA. Both groups, however, displayed increased insulin sensitivity during exercise that was accompanied by a normalization of the elevated fasting glucose in the overweight/obese group after 15-20 min.

CONCLUSION

We conclude that the response to exercise in overweight/obese subjects indeed differs from that in lean individuals. Additionally, we demonstrate that exercise can elicit beneficial (improved glucose regulation) and unwanted effects (stress axis activation) in overweight/obese subjects at the same time. This second finding suggests that exercise interventions for overweight/obese subjects need careful consideration of intensity and dose in order to achieve the intended results and avoid acute, undesired reactions.

An NMR-Based Approach to Identify Urinary Metabolites Associated with Acute Physical Exercise and Cardiorespiratory Fitness in Healthy Humans-Results of the KarMeN Study

Knowledge on metabolites distinguishing the metabolic response to acute physical exercise between fit and less fit individuals could clarify mechanisms and metabolic pathways contributing to the beneficial adaptations to exercise. By analyzing data from the cross-sectional KarMeN (Karlsruhe Metabolomics and Nutrition) study, we characterized the acute effects of a standardized exercise tolerance test on urinary metabolites of 255 healthy women and men. In a second step, we aimed to detect a urinary metabolite pattern associated with the cardiorespiratory fitness (CRF), which was determined by measuring the peak oxygen uptake (VO_2peak) during incremental exercise. Spot urine samples were collected pre- and post-exercise and 47 urinary metabolites were identified by nuclear magnetic resonance (NMR) spectroscopy. While the univariate analysis of pre-to-post-exercise differences revealed significant alterations in 37 urinary metabolites, principal component analysis (PCA) did not show a clear separation of the pre- and post-exercise urine samples. Moreover, both bivariate correlation and multiple linear regression analyses revealed only weak relationships between the VO_2peak and single urinary metabolites or urinary metabolic pattern, when adjusting for covariates like age, sex, menopausal status, and lean body mass (LBM). Taken as a whole, our results show that several urinary metabolites (e.g., lactate, pyruvate, alanine, and acetate) reflect acute exercise-induced alterations in the human metabolism. However, as neither pre- and post-exercise levels nor the fold changes of urinary metabolites substantially accounted for the variation of the covariate-adjusted VO_2peak, our results furthermore indicate that the urinary metabolites identified in this study do not allow to draw conclusions on the individual's physical fitness status. Studies investigating the relationship between the human metabolome and functional variables like the CRF should adjust for confounders like age, sex, menopausal status, and LBM.

Runners' metabolomic changes following marathon

Introduction

Marathon, as a long-distance aerobic exercise, has become a fashionable or popular sport. However, little is known about the holistic metabolic changes occurring within the serum metabolome of athletes after the completion of a marathon.

Objectives

The goal of current study was to have an in-depth understanding of the impact of marathon on human metabolomics as well as the relationships among a variety of metabolites.

Methods

The 20 studied subjects were all adult males who participated in a marathon. The serum samples of these participants were collected before and after the marathon and the biochemical metabolites in the serum were identified by an untargeted two-dimensional gas chromatography time-of-flight mass spectrometry.

Results

All participants completed the marathon within 3 h. Compared to those before exercise, serum urea and creatine kinase, as well as cortisol, elevated significantly (p < 0.05), whereas testosterone decreased significantly (p < 0.01). Metabolomic analysis showed that, compared to those before the competition, metabolites pyruvic acid, glyceric acid, malic acid, cis-aconitic acid, galacturonic acid, methyl fumaric acid, maltotriose, and others increased significantly after the competition (p < 0.05), but glucosamine and O-succinyl-L-homoserine decreased significantly (p < 0.05). Amino acid indexes, such as alanine, L-tyrosine and phenylalanine, increased significantly after exercise compared with those before exercise (p < 0.05), whereas serine, valine and asparagine decreased significantly (p < 0.05). Lipid metabolism indexes, glycerol, glyceric acid, octanoic acid, and quinic acid increased significantly (p < 0.05). Theophylline, xanthine and other indicators of caffeine metabolism increased significantly (p < 0.05). Furthermore, marathon performance, fat percentage, VO₂max, and hemoglobin were correlated with the serum metabonomic indicators, so were serum testosterone and cortisol.

Conclusion

These results illustrate that the metabolism of glucose and lipid of the athletes was enhanced following the marathon match. In addition, the metabolism of glucosamine was decreased and the metabolism of caffeine was increased. Our data provide new insights for marathon performance and nutritional status.

Metabolite Concentration Changes in Humans After a Bout of Exercise: a Systematic Review of Exercise Metabolomics Studies

Background

Exercise changes the concentrations of many metabolites, which are small molecules (< 1.5 kDa) metabolized by the reactions of human metabolism. In recent years, especially mass spectrometry-based metabolomics methods have allowed researchers to measure up to hundreds of metabolites in a single sample in a non-biased fashion. To summarize human exercise metabolomics studies to date, we conducted a systematic review that reports the results of experiments that found metabolite concentrations changes after a bout of human endurance or resistance exercise.

Methods

We carried out a systematic review following PRISMA guidelines and searched for human metabolomics studies that report metabolite concentrations before and within 24 h after endurance or resistance exercise in blood, urine, or sweat. We then displayed metabolites that significantly changed their concentration in at least two experiments.

Results

Twenty-seven studies and 57 experiments matched our search criteria and were analyzed. Within these studies, 196 metabolites changed their concentration significantly within 24 h after exercise in at least two experiments. Human biofluids contain mainly unphosphorylated metabolites as the phosphorylation of metabolites such as ATP, glycolytic intermediates, or nucleotides traps these metabolites within cells. Lactate, pyruvate, TCA cycle intermediates, fatty acids, acylcarnitines, and ketone bodies all typically increase after exercise, whereas bile acids decrease. In contrast, the concentrations of proteinogenic and non-proteinogenic amino acids change in different directions.

Conclusion

Across different exercise modes and in different subjects, exercise often consistently changes the average concentrations of metabolites that belong to energy metabolism and other branches of metabolism. This dataset is a useful resource for those that wish to study human exercise metabolism.

Exercise plasma metabolomics and xenometabolomics in obese, sedentary, insulin-resistant women: impact of a fitness and weight loss intervention

Insulin resistance has wide-ranging effects on metabolism, but there are knowledge gaps regarding the tissue origins of systemic metabolite patterns and how patterns are altered by fitness and metabolic health. To address these questions, plasma metabolite patterns were determined every 5 min during exercise (30 min, ∼45% of V̇o_2peak, ∼63 W) and recovery in overnight-fasted sedentary, obese, insulin-resistant women under controlled conditions of diet and physical activity. We hypothesized that improved fitness and insulin sensitivity following a ∼14-wk training and weight loss intervention would lead to fixed workload plasma metabolomics signatures reflective of metabolic health and muscle metabolism. Pattern analysis over the first 15 min of exercise, regardless of pre- versus postintervention status, highlighted anticipated increases in fatty acid tissue uptake and oxidation (e.g., reduced long-chain fatty acids), diminution of nonoxidative fates of glucose [e.g., lowered sorbitol-pathway metabolites and glycerol-3-galactoside (possible glycerolipid synthesis metabolite)], and enhanced tissue amino acid use (e.g., drops in amino acids; modest increase in urea). A novel observation was that exercise significantly increased several xenometabolites ("non-self" molecules, from microbes or foods), including benzoic acid-salicylic acid-salicylaldehyde, hexadecanol-octadecanol-dodecanol, and chlorogenic acid. In addition, many nonannotated metabolites changed with exercise. Although exercise itself strongly impacted the global metabolome, there were surprisingly few intervention-associated differences despite marked improvements in insulin sensitivity, fitness, and adiposity. These results and previously reported plasma acylcarnitine profiles support the principle that most metabolic changes during submaximal aerobic exercise are closely tethered to absolute ATP turnover rate (workload), regardless of fitness or metabolic health status.

High intensity interval training and molecular adaptive response of skeletal muscle

Increased cardiovascular fitness, V˙O_2max, is associated with enhanced endurance capacity and a decreased rate of mortality. High intensity interval training (HIIT) is one of the best methods to increase V˙O_2max and endurance capacity for top athletes and for the general public as well. Because of the high intensity of this type of training, the adaptive response is not restricted to Type I fibers, as found for moderate intensity exercise of long duration. Even with a short exercise duration, HIIT can induce activation of AMPK, PGC-1α, SIRT1 and ROS pathway as well as by the modulation of Ca²⁺ homeostasis, leading to enhanced mitochondrial biogenesis, and angiogenesis. The present review summarizes the current knowledge of the adaptive response of HIIT.

Paradoxical Rise in Hypoglycemia Symptoms With Development of Hyperglycemia During High-Intensity Interval Training in Type 1 Diabetes

OBJECTIVE

To assess the reliability of self-perception of glycemia during high-intensity interval training (HIIT) in subjects with type 1 diabetes.

RESEARCH DESIGN AND METHODS

This randomized crossover study included subjects who completed four fasted HIIT sessions. Subjects answered the Edinburgh Hypoglycemia Scale, estimated their blood glucose (BG), and had plasma glucose (PG) collected throughout exercise and recovery.

RESULTS

As PG increased throughout exercise, hypoglycemia scores increased across each category: autonomic (3.1-4.4, P < 0.05), neuroglycopenic (1.5-2.4, P < 0.05), and nonspecific (1.3-1.9, P < 0.05). Subjects' estimated BG showed a negative bias that widened as exercise progressed and peaked at -1.6 ± 3.3 mmol/L (P < 0.001) postinsulin correction.

CONCLUSIONS

During HIIT, despite progressing hyperglycemia, subjects experience increased hypoglycemia symptoms and tend to underestimate their BG level.

Metabolomics-Based Studies Assessing Exercise-Induced Alterations of the Human Metabolome: A Systematic Review

This systematic review provides a qualitative appraisal of 24 high-quality metabolomics-based studies published over the past decade exploring exercise-induced alterations of the human metabolome. Of these papers, 63% focused on acute metabolite changes following intense and prolonged exercise. The best studies utilized liquid chromatography mass spectrometry (LC-MS/MS) analytical platforms with large chemical standard libraries and strong, multivariate bioinformatics support. These studies reported large-fold changes in diverse lipid-related metabolites, with more than 100 increasing two-fold or greater within a few hours post-exercise. Metabolite shifts, even after strenuous exercise, typically return to near pre-exercise levels after one day of recovery. Few studies investigated metabolite changes following acute exercise bouts of shorter durations (< 60 min) and workload volumes. Plasma metabolite shifts in these types of studies are modest in comparison. More cross-sectional and exercise training studies are needed to improve scientific understanding of the human system’s response to varying, chronic exercise workloads. The findings derived from this review provide direction for future investigations focused on the body’s metabolome response to exercise.

Do adjuvant interventions improve treatment outcome in adult patients with posttraumatic stress disorder receiving trauma-focused psychotherapy? A systematic review

Background: According to clinical guidelines, trauma-focused psychotherapies (TF-PT) such as trauma-focused cognitive behavioural therapy (TF-CBT) and eye movement desensitization and reprocessing (EMDR) are recommended as first-line treatments for posttraumatic stress disorder (PTSD). TF-CBT and EMDR are equally effective and have large effect sizes. However, many patients fail to respond or have comorbid symptoms or disorders that only partially decline with TF-PT. Thus, there is growing interest in augmenting TF-PT through adjuvant interventions. Objective: The current systematic review aims to assess whether adjuvant interventions improve outcome among adult PTSD patients receiving TF-PT. Methods: We searched the databases PubMed, PILOTS, Web of Science and the Cochrane Library for controlled clinical trials examining whether adjuvant interventions lead to more symptom reduction in adult PTSD patients receiving TF-PT. Thirteen randomized controlled trials fitted the inclusion criteria. These were evaluated for internal risk of bias using the Cochrane Handbook for Systematic Review of Interventions. Results: Most studies have a substantial risk for internal bias, mainly due to small sample sizes. Thus, no strong conclusion can be drawn from the current empirical evidence. Preliminary evidence suggests that exercise and cortisol administration may have an adjuvant effect on PTSD symptom reduction. Breathing biofeedback showed a trend for an adjuvant effect and an effect for accelerated symptom reduction. Conclusions: Currently, it is not possible to formulate evidence-based clinical recommendations regarding adjuvants interventions. While several adjuvant interventions hold the potential to boost the effectiveness of TF-PT, the realization of sufficiently powered studies is crucial to separate plausible ideas from interventions proven to work in practice.

High-Intensity Interval Training Decreases Resting Urinary Hypoxanthine Concentration in Young Active Men-A Metabolomic Approach

High-intensity interval training (HIIT) is known to improve performance and skeletal muscle energy metabolism. However, whether the body’s adaptation to an exhausting short-term HIIT is reflected in the resting human metabolome has not been examined so far. Therefore, a randomized controlled intervention study was performed to investigate the effect of a ten-day HIIT on the resting urinary metabolome of young active men. Fasting spot urine was collected before (−1 day) and after (+1 day; +4 days) the training intervention and 65 urinary metabolites were identified by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) spectroscopy. Metabolite concentrations were normalized to urinary creatinine and subjected to univariate statistical analysis. One day after HIIT, no overall change in resting urinary metabolome, except a significant difference with decreasing means in urinary hypoxanthine concentration, was documented in the experimental group. As hypoxanthine is related to purine degradation, lower resting urinary hypoxanthine levels may indicate a training-induced adaptation in purine nucleotide metabolism.

Effect of interval exercise versus continuous exercise on excess post-exercise oxygen consumption during energy-homogenized exercise on a cycle ergometer

PURPOSE

The purpose of this study was to confirm that the difference in excess post-exercise oxygen consumption (EPOC) during exercise of the spending the same calories between the continuous and interval exercise.

METHODS

Thirty-four healthy college students who did not regularly exercise volunteered to participate in our study. Continuous exercise was performed on an ergometer for 30 min at 60% of maximal oxygen consumption (VO2 max). Interval exercise was performed on a cycle ergometer at 80% VO2 max for 2 min initially, followed by 40% VO2 max for 1 min, and 80% VO2 max for 3 min. This was repeated six times for a total of 26 min.

RESULTS

The major findings were as follows: (1) energy consumption during exercise was not significantly different between continuous exercise and interval exercise groups; (2) EPOC was higher in interval exercise than in continuous exercise for all dependent variables (i.e., total oxygen consumption, total calories, summation of heart rate); and (3) there were no significant differences in the lipid profile between continuous and interval groups.

CONCLUSION

Our study confirmed that after equalizing energy expenditure for continuous and interval exercise on a cycle ergometer in subjects in their twenties, interval exercise results in higher EPOC than continuous exercise. These data suggest that interval exercise may be more effective than continuous exercise in reducing body fat, for a given amount of energy expenditure.

Effects of Boxing Matches on Metabolic, Hormonal, and Inflammatory Parameters in Male Elite Boxers

Background and objectives: Boxing is a popular combat sport that requires high intensity and cooperation. However, there are limited data about the influence of boxing matches on blood parameters. The purpose of the present study was to investigate the match-induced changes in the metabolic, hormonal, and inflammatory status in male elite boxers. Materials and methods: High-level 20 male boxers with more than 5 years experience in boxing voluntarily participated in this study. Venous blood samples of the boxers, before and after combat, were taken for determination of the plasma parameters. Results: Our results indicated that a 9-min boxing match caused significant increases in plasma energy fuels (glucose and lactate), metabolic hormones (insulin, adrenocorticotropic hormone (ACTH), cortisol, and growth hormone), inflammatory markers (interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α)), muscle damage indicators (alanine aminotransferase (ALT) and aspartate aminotransferase (AST)), and oxidative stress marker (SOD). A decrease in total oxidant status (TOS) was also considered. However, there were no significant alterations in the plasma levels of androgenic hormone (free and total testosterone), anabolic hormone (IGF-1), lipids (total cholesterol, triglyceride, high-density lipoprotein (HDL), and low-density lipoprotein (LDL)), kidney function markers (creatinine and urea), and minerals (iron (Fe) and magnesium (Mg)). Conclusion: Elevations in the level of energy fuels and metabolic hormones of the boxers could be taken as a reflection of high-energy turnover during combat performance. The increases in inflammatory and tissue damage indicators may possibly be an indication of traumatic injury. Understanding the biochemical changes that occur during boxing match could be valuable to optimize the performance improvement of the athletes.

Comparison of the Serum Metabolic Fingerprint of Different Exercise Modes in Men with and without Metabolic Syndrome

Exercise plays a beneficial role in the treatment of metabolic syndrome (MetS). Metabolomics can provide new insights and facilitate the optimization of exercise prescription. This study aimed to investigate whether the response of the human serum metabolic fingerprint to exercise depends on exercise mode or the presence of MetS. Twenty-three sedentary men (nine with MetS and fourteen healthy) completed four trials: Resting, high-intensity interval exercise (HIIE), continuous moderate-intensity exercise (CME), and resistance exercise (RE). Blood samples were collected pre-exercise, immediately after exercise, and 1 h post-exercise for targeted metabolomic analysis in serum by liquid chromatography–mass spectrometry. Time exerted the strongest differentiating effect, followed by exercise mode. The largest changes from baseline were found in the immediate post-exercise samples. RE caused the strongest responses overall, followed by HIIE, while CME had minimal effect. Unlike previous results in urine, no valid model could separate the two groups in serum. Exercise exerted a beneficial effect on prominent serum biomarkers of metabolic risks, such as branched-chain amino acids, alanine, acetylcarnitine, choline, and betaine. These findings contribute to the ongoing research efforts to map the molecular responses to exercise and to optimize exercise guidelines for individuals at cardiometabolic risk.

Effects of High-Intensity Interval Training Versus Moderate-Intensity Training on Cardiometabolic Health Markers in Individuals With Spinal Cord Injury: A Pilot Study

Background: Recent studies in nondisabled individuals have demonstrated that low-volume high-intensity interval training (HIIT) can improve cardiometabolic health similar to moderate-intensity training (MIT) despite requiring 20% of the overall time commitment. To date, there have been no studies assessing the effects of HIIT for improving cardiometabolic health in individuals with SCI. Objectives: The primary purpose of this pilot study was to compare the effects of 6 weeks of low-volume HIIT vs MIT using arm crank ergometer exercise to improve body composition, cardiovascular fitness, glucose tolerance, blood lipids, and blood pressure in a cohort of individuals with longstanding SCI. Methods: Participants were randomized to 6 weeks of HIIT or MIT arm crank exercise training. Aerobic capacity, muscular strength, blood lipids, glucose tolerance, blood pressure, and body composition were assessed at baseline and 6 weeks post training. Results: Seven individuals (6 male, 1 female; n = 3 in MIT and n = 4 in HIIT; mean age 51.3 ± 10.5 years) with longstanding SCI completed the study. The preliminary findings from this pilot study demonstrated that individuals with SCI randomized to either 6 weeks of HIIT or MIT displayed improvements in (a) insulin sensitivity, (b) cardiovascular fitness, and (c) muscular strength (p < .05). However, MIT led to greater improvements in arm fat percent and chest press strength compared to HIIT (p < .05). Conclusion: No differences between MIT and HIIT were observed. Both conditions led to improvements in insulin sensitivity, aerobic capacity, muscle strength, and blood lipids in individuals with SCI. Future larger cohort studies are needed to determine if the shorter amount of time required from HIIT is preferable to current MIT exercise recommendations.

Metabolite Changes in Maternal and Fetal Plasma Following Spontaneous Labour at Term in Humans Using Untargeted Metabolomics Analysis: A Pilot Study

The mechanism of human labour remains poorly understood, limiting our ability to manage complications of parturition such as preterm labour and induction of labour. In this study we have investigated the effect of labour on plasma metabolites immediately following delivery, comparing cord and maternal plasma taken from women who laboured spontaneously and delivered vaginally with women who were delivered via elective caesarean section and did not labour. Samples were analysed using ultra high-performance liquid chromatography-tandem mass spectrometry. Welch’s two-sample t-test was used to identify any significant differences. Of 826 metabolites measured, 26.9% (222/826) were significantly altered in maternal plasma and 21.1% (174/826) in cord plasma. Labour involves changes in many maternal organs and poses acute metabolic demands in the uterus and in the fetus and these are reflected in our results. While a proportion of these differences are likely to be secondary to the physiological demands of labour itself, these results present a comprehensive picture of the metabolome in the maternal and fetal circulations at the time of delivery and can be used to guide future studies. We discuss potential causal pathways for labour including endocannabinoids, ceramides, sphingolipids and steroids. Further work is necessary to confirm the specific pathways involved in the spontaneous onset of labour.

Metabolic profiling of elite athletes with different cardiovascular demand

Intensive exercise of elite athletes can lead to physiological alterations in the cardiovascular system in response to increased stroke volume and blood pressure, known collectively as cardiovascular demand (CD). This study aimed to compare metabolic differences in elite athletes with high vs low/moderate CD and to reveal their underlying metabolic pathways as potential biomarker signatures for assessing health, performance, and recovery of elite athletes. Metabolic profiling of serum samples from 495 elite athletes from different sport disciplines (118 high CD and 377 low/moderate CD athletes) was conducted using non-targeted metabolomics-based mass spectroscopy combined with ultra-high-performance liquid chromatography. Results show that DAGs containing arachidonic were enriched in high CD together with branched-chain amino acids, plasminogens, phosphatidylcholines, and phosphatidylethanolamines, potentially indicating increased risk of cardiovascular disease in the high CD group. Gamma-glutamyl amino acids and glutathione metabolism were increased in low/moderate CD group, suggesting more efficient oxidative stress scavenging mechanisms than the high CD group. This first most comprehensive metabolic profiling of elite athletes provides an evidence that athletes with different CD show a unique metabolic signature that reflects energy generation and oxidative stress and potentially places the high CD group at a higher risk of cardiovascular disease. Further studies are warranted for confirmation and validation of findings in other sport groups in light of potential confounders related to limited available information about participants.

Afternoon exercise is more efficacious than morning exercise at improving blood glucose levels in individuals with type 2 diabetes: a randomised crossover trial

AIMS/HYPOTHESIS

Exercise is recommended for the treatment and prevention of type 2 diabetes. However, the most effective time of day to achieve beneficial effects on health remains unknown. We aimed to determine whether exercise training at two distinct times of day would have differing effects on 24 h blood glucose levels in men with type 2 diabetes.

METHODS

Eleven men with type 2 diabetes underwent a randomised crossover trial. Inclusion criteria were 45-68 years of age and BMI between 23 and 33 kg/m². Exclusion criteria were insulin treatment and presence of another systemic illness. Researchers were not blinded to the group assignment. The trial involved 2 weeks of either morning or afternoon high-intensity interval training (HIIT) (three sessions/week), followed by a 2 week wash-out period and a subsequent period of the opposite training regimen. Continuous glucose monitor (CGM)-based data were obtained.

RESULTS

Morning HIIT increased CGM-based glucose concentration (6.9 ± 0.4 mmol/l; mean ± SEM for the exercise days during week 1) compared with either the pre-training period (6.4 ± 0.3 mmol/l) or afternoon HIIT (6.2 ± 0.3 mmol/l for the exercise days during week 1). Conversely, afternoon HIIT reduced the CGM-based glucose concentration compared with either the pre-training period or morning HIIT. Afternoon HIIT was associated with elevated thyroid-stimulating hormone (TSH; 1.9 ± 0.2 mU/l) and reduced T₄ (15.8 ± 0.7 pmol/l) concentrations compared with pre-training (1.4 ± 0.2 mU/l for TSH; 16.8 ± 0.6 pmol/l for T₄). TSH was also elevated after morning HIIT (1.7 ± 0.2 mU/l), whereas T₄ concentrations were unaltered.

CONCLUSIONS/INTERPRETATION

Afternoon HIIT was more efficacious than morning HIIT at improving blood glucose in men with type 2 diabetes. Strikingly, morning HIIT had an acute, deleterious effect, increasing blood glucose. However, studies of longer training regimens are warranted to establish the persistence of this adverse effect. Our data highlight the importance of optimising the timing of exercise when prescribing it as treatment for type 2 diabetes.

Effects of HIIT and MICT on cardiovascular risk factors in adults with overweight and/or obesity: A meta-analysis

Objective

The purpose of this study was to evaluate the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on cardiovascular disease (CVD) risk factors in adults with overweight and obesity.

Methods

Twenty-two articles were included by searching six databases, the total number of subjects was 620 in these articles. Outcomes were synthesised using a random-effects meta-analysis of the Standardized mean difference (SMD) in CVD risk factors.

Results

HIIT and MICT resulted in statistically significant reductions in Weight, BMI, fat%, total cholesterol(TC), and improvement in VO_2max. Compared with MICT, subgroup of durations of HIIT training interval ≥2 min can significantly increase VO_2max (SMD = 0.444, 95% CI:0.037~0.851,P = 0.032), subgroup of energy expenditure of HIIT equal to MICT can significantly increase VO_2max (SMD = 0.399, 95% CI:0.106~0.692,P = 0.008).

Conclusions

HIIT appears to provide similar benefits to MICT for improving body composition, VO_2maxand TC, but HIIT spent less time than MICT by 9.7 min on one session. HIIT is superior to MICT in improving cardiopulmonary fitness when durations of HIIT training interval ≥2 min or energy expenditure of HIIT same as MICT. PROSPERO ID: CRD42016045835.

Skeletal muscle interstitial fluid metabolomics at rest and associated with an exercise bout: application in rats and humans

Blood or biopsies are often used to characterize metabolites that are modulated by exercising muscle. However, blood has inputs derived from multiple tissues, biopsies cannot discriminate between secreted and intracellular metabolites, and their invasive nature is challenging for frequent collections in sensitive populations (e.g., children and pregnant women). Thus, minimally invasive approaches to interstitial fluid (IF) metabolomics would be valuable. A catheter was designed to collect IF from the gastrocnemius muscle of acutely anesthetized adult male rats at rest or immediately following 20 min of exercise (~60% of maximal O₂ uptake). Nontargeted, gas chromatography-time-of-flight mass spectrometry analysis was used to detect 299 metabolites, including nonannotated metabolites, sugars, fatty acids, amino acids, and purine metabolites and derivatives. Just 43% of all detected metabolites were common to IF and blood plasma, and only 20% of exercise-modified metabolites were shared in both pools, highlighting that the blood does not fully reflect the metabolic outcomes in muscle. Notable exercise patterns included increased IF amino acids (except leucine and isoleucine), increased α-ketoglutarate and citrate (which may reflect tricarboxylic acid cataplerosis or shifts in nonmitochondrial pathways), and higher concentration of the signaling lipid oleamide. A preliminary study of human muscle IF was conducted using a 20-kDa microdialysis catheter placed in the vastus lateralis of five healthy adults at rest and during exercise (65% of estimated maximal heart rate). Approximately 70% of commonly detected metabolites discriminating rest vs. exercise in rats were also changed in exercising humans. Interstitium metabolomics may aid in the identification of molecules that signal muscle work (e.g., exertion and fatigue) and muscle health.

Excess Postexercise Oxygen Consumption and Fat Utilization Following Submaximal Continuous and Supramaximal Interval Running

PURPOSE

Few studies have directly compared excess postexercise oxygen consumption (EPOC) and fat utilization following different exercise intensities, and the effect of continuous exercise exceeding 75% of maximal oxygen uptake (VO₂max) on these parameters remains unexplored. The current study examined EPOC and fat utilization following acute moderate- and vigorous-intensity continuous training (MICT and VICT) and sprint interval training (SIT).

METHODS

Eight active young men performed 4 experimental sessions: (a) MICT (30 min of running at 65% VO₂max); (b) VICT (30 min of running at 85% VO₂max); (c) SIT (4 30-s "all-out" sprints with 4 min of rest); and (d) no exercise (REST). Excess postexercise oxygen consumption and fat oxidation were estimated from gas measurements (VO₂ and carbon dioxide production [VCO₂]) obtained during a 2-hr postexercise period.

RESULTS

Total EPOC was similar (p = .097; effect size [ES] = 0.3) after VICT (8.6 ± 4.7 L) and SIT (10.0 ± 4.2 L) and greater after both (VICT, p = .025, ES = 0.3, and SIT, p < .001, ES = 0.6) versus MICT (6.0 ± 4.3 L). Fat utilization increased after MICT (0.047 ± 0.018 g· min^-1, p = .018, ES = 1.3), VICT (0.066 ± 0.020 g•min^-1, p = .034, ES = 2.2), and SIT (0.115 ± 0.026 g•min^-1, p < .001, ES = 4.0) versus REST (0.025 ± 0.018 g•min^-1) and was greatest after SIT (p < .001, ES = 3.0 vs. MICT; p = .031, ES = 2.1 vs. VICT).

CONCLUSION

Acute exercise increases EPOC and fat utilization in an intensity-dependent manner.

The altered human serum metabolome induced by a marathon

INTRODUCTION

Endurance races have been associated with a substantial amount of adverse effects which could lead to chronic disease and long-term performance impairment. However, little is known about the holistic metabolic changes occurring within the serum metabolome of athletes after the completion of a marathon.

OBJECTIVES

Considering this, the aim of this study was to better characterize the acute metabolic changes induced by a marathon.

METHODS

Using an untargeted two dimensional gas chromatography time-of-flight mass spectrometry metabolomics approach, pre- and post-marathon serum samples of 31 athletes were analyzed and compared to identify those metabolites varying the most after the marathon perturbation.

RESULTS

Principle component analysis of the comparative groups indicated natural differentiation due to variation in the total metabolite profiles. Elevated concentrations of carbohydrates, fatty acids, tricarboxylic acid cycle intermediates, ketones and reduced concentrations of amino acids indicated a metabolic shift between various fuel substrate systems. Additionally, elevated odd-chain fatty acids and α-hydroxy acids indicated the utilization of α-oxidation and autophagy as alternative energy-producing mechanisms. Adaptations in gut microbe-associated markers were also observed and correlated with the metabolic flexibility of the athlete.

CONCLUSION

From these results it is evident that a marathon places immense strain on the energy-producing pathways of the athlete, leading to extensive protein degradation, oxidative stress, mammalian target of rapamycin complex 1 inhibition and autophagy. A better understanding of this metabolic shift could provide new insights for optimizing athletic performance, developing more efficient nutrition regimens and identify strategies to improve recovery.

Hepatokines-a novel group of exercise factors

Regular physical activity not only improves the exercise capacity of the skeletal muscle performing the contractions, but it is beneficial for the whole body. An extensive search for "exercise factors" mediating these beneficial effects has been going on for decades. Particularly skeletal muscle tissue has been investigated as a source of circulating exercise factors, and several myokines have been identified. However, exercise also has an impact on other tissues. The liver is interposed between energy storing and energy utilising tissues and is highly active during exercise, maintaining energy homeostasis. Recently, a novel group of exercise factors-termed hepatokines-has emerged. These proteins (fibroblast growth factor 21, follistatin, angiopoietin-like protein 4, heat shock protein 72, insulin-like growth factor binding protein 1) are released from the liver and increased in the bloodstream during or in the recovery after an exercise bout. In this narrative review, we evaluate this new group of exercise factors focusing on the regulation and potential function in exercise metabolism and adaptations. These hepatokines may convey some of the beneficial whole-body effects of exercise that could ameliorate metabolic diseases, such as obesity or type 2 diabetes.

Beneficial alterations in body composition, physical performance, oxidative stress, inflammatory markers, and adipocytokines induced by long-term high-intensity interval training in an aged rat model

Sarcopenia is associated with loss of muscle mass and function as well as oxidative stress, chronic low-grade inflammatory status, and adipocytokine dysfunction. It has been reported that sarcopenia can be attenuated by exercise training. The purpose of this study was to evaluate whether long-term high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) protocols could differentially modulate changes in body composition, physical performance, inflammatory parameters, and adipocytokines in fat tissues and serum, as well as oxidative parameters and insulin-like growth factor 1 (IGF-1) levels in skeletal muscle tissue of aged rats. Middle-aged (18-month-old) female Sprague Dawley rats (n = 36) were subjected to 8 months of MICT (26-m MICT) or HIIT (26-m HIIT) treadmill training (45 min, 5 times per week), and the results were compared with those of age-matched sedentary controls (26-m SED); 8-month-old (8-m SED) and 18-month-old (18-m SED) rats served as aging sedentary controls. Body composition parameters; physical performance; serum and skeletal muscle oxidative stress parameters; levels of IGF-1, a serum and fat tissue inflammatory marker; adipocytokine (leptin, adiponectin) levels; and plasma glucose and lipid metabolism-related parameters were analyzed among the five groups. The percent fat and body fat to lean mass ratio increased as a main effect with age, whereas 26-m HIIT but not 26-m MICT attenuated these alterations. The 26-m HIIT group showed a larger improvement in grip strength compared to that of 26-m MICT, with a similar increase in inclined plane performance, maximum running speed, and exhaustion over time as compared with the 26-m SED group. Notably, the 26-m HIIT group showed lower high-sensitivity C-reactive protein levels and higher IL-10 in serum compared with those of the 26-m SED and 26-m MICT groups. Both exercise protocols promoted increased skeletal muscle IGF-1 and decreased serum IGF-1 and adiponectin relative to those in the 26-m SED group, whereas only 26-m HIIT dampened the age-related decrease in plasma free fatty acids and increased serum leptin, along with providing lower fat tissue leptin as compared with that in the 26-m SED group. Moreover, the 26-m HIIT group showed lower serum and skeletal muscle malonylaldehyde and skeletal muscle 8-hydroxydeoxyguanosine (8-OHdG) levels than those in the 26-m MICT group, albeit similar decreases in serum and skeletal muscle 4-hydroxynonenal and serum 8-OHdG and increases in skeletal muscle superoxide dismutase 2 activity. In conclusion, HIIT initiated late in life exhibited greater beneficial effects in ameliorating aged-related elevations in oxidative stress and inflammation, as well as dysfunction of circulating adipocytokine levels, than a volume-matched MICT program. HIIT may therefore contribute to improvements in body composition and physical performance changes associated with aging.

Post-Exercise Appetite and Ad Libitum Energy Intake in Response to High-Intensity Interval Training versus Moderate- or Vigorous-Intensity Continuous Training among Physically Inactive Middle-Aged Adults

High-intensity interval training (HIIT) is considered a time-efficient exercise strategy for weight management. However, data regarding the acute appetite and energy intake responses to HIIT versus continuous training remain inconclusive. This study investigated the ad libitum energy intake and appetite responses to a single session of HIIT versus moderate-intensity continuous training (MICT) and vigorous-intensity continuous training (VICT). Using a randomized crossover design, 11 middle-aged physically inactive men (45.7 ± 7.4 years, 23.5 ± 2.1 kg m^-2) participated in three treadmill trials at 7-day intervals. HIIT comprised 10 1-min periods at 100% VO_2max interspersed with 1-min periods of active recovery. MICT comprised a 40-min session at 65% VO_2max, while VICT comprised a 20-min session at 80% VO_2max. After each trial, the participants consumed an ad libitum buffet meal for which the energy intake was recorded. The participants' perceived appetite was assessed before and after exercise sessions using the Visual Analogue Scale (VAS). No significant differences in post-exercise ad libitum energy intake were observed between trials (HIIT: 645 ± 262.9 kcal; MICT: 614.7 ± 271.2 kcal; VICT: 623.1 ± 249.0 kcal, p > 0.05). Although the perceived appetite responses exhibited a significant main effect of time (p < 0.01), no group differences were observed (p > 0.05). In summary, these findings suggest that the interval or continuous nature of exercise has no significant effect on appetite responses in physically inactive middle-aged adults, at least during the short-term post-exercise period.

Testosterone and Cortisol Responses to Five High-Intensity Functional Training Competition Workouts in Recreationally Active Adults

To determine the salivary steroid response to high-intensity functional training (HIFT) competition workouts, saliva samples were collected from ten recreationally trained male and female competitors during a 5-week (WK1–WK5) international competition. Competitors arrived at their local affiliate and provided samples prior to (PRE) their warm-up, immediately (IP), 30-min (30P), and 60-min (60P) post-exercise. Samples were analyzed for concentrations of testosterone (T), cortisol (C), and their ratio (TC). Generalized linear mixed models with repeated measures revealed significant main effects for time (p < 0.001) for T, C, and TC. Compared to PRE-concentrations, elevated (p < 0.05) T was observed at IP on WK2–WK5 (mean difference: 135–511 pg·mL⁻¹), at 30P on WK3 (mean difference: 81.0 ± 30.1 pg·mL⁻¹) and WK5 (mean difference: 56.6 ± 22.7 pg·mL⁻¹), and at 60P on WK3 (mean difference: 73.5 ± 29.7 pg·mL⁻¹) and WK5 (mean difference: 74.3 ± 28.4 pg·mL⁻¹). Compared to PRE-concentrations, elevated (p < 0.05) C was noted on all weeks at IP (mean difference: 9.3–15.9 ng·mL⁻¹) and 30P (mean difference: 6.0–19.9 ng·mL⁻¹); significant (p < 0.006) elevations were noted at 60P on WK1 (mean difference: 9.1 ± 3.0 ng·mL⁻¹) and WK5 (mean difference: 12.8 ± 2.9 ng·mL⁻¹). Additionally, TC was significantly reduced from PRE-values by 61% on WK1 at 60P (p = 0.040) and by 80% on WK5 at 30P (p = 0.023). Differences in T, C, and TC were also observed between weeks at specific time points. Although each workout affected concentrations in T, C, and/or the TC ratio, changes appeared to be modulated by the presence of overload and workout duration. During periods of elevated training or competition, athletes and coaches may consider monitoring these hormones for consistency and as a means of assessing workout difficulty.

Acute Effects of High-Intensity Interval and Moderate-Intensity Continuous Exercise on GLP-1, Appetite and Energy Intake in Obese Men: A Crossover Trial

This study investigated the effect of high-intensity interval (HIIE) and moderate-intensity continuous exercise (MICE) on glucagon-like peptide 1 (GLP-1), appetite and energy intake (EI) in obese men. In a randomized crossover trial, 12 participants (28.4 ± 2.6 years, 35.5 ± 4.5 kg/m², 39.8 ± 2.2% body fat) performed: (I) Control (CON, no exercise); (II) MICE (20 min, 70% of maximal heart rate) and (III) HIIE (10 × 1 min at 90% of maximal heart rate with 1 min recovery). GLP-1 and appetite were assessed at: (I) PRE: pre-exercise; (II) POST: immediately post-exercise; (III) POST-1 h: 1 h post-exercise. EI was assessed after an ad libitum meal offered 1 h post-exercise and over 24 h. There was a significant time × condition interaction for GLP-1 (p = 0.035). Higher GLP-1 levels in MICE vs. CON (p = 0.024) and a trend for HIIE vs. CON (p = 0.069) POST-1h was found. Hunger was reduced immediately post-HIIE compared to CON (p < 0.01), but was not sustained POST-1 h (p > 0.05). EI did not differ between the sessions 1 h post-exercise or over 24H (p > 0.05). In summary, although MICE increased GLP-1 levels POST-1h and HIIE induced a transient reduction in hunger, both exercise protocols did not impact EI in obese men.

Impact of Endurance Exercise Training in the Fasted State on Muscle Biochemistry and Metabolism in Healthy Subjects: Can These Effects be of Particular Clinical Benefit to Type 2 Diabetes Mellitus and Insulin-Resistant Patients?

Exercise training intervention is a cornerstone in the care of type 2 diabetes mellitus (T2DM) and insulin resistance (IR), and it is pursued in order to optimize exercise interventions for these patients. In this regard, the nutritional state of patients during exercise (being in the fed or fasted state) can be of particular interest. The aim of the present review is to describe the impact of endurance exercise (training) in the fasted versus fed state on parameters of muscle biochemistry and metabolism linked to glycemic control or insulin sensitivity in healthy subjects. From these data it can then be deduced whether exercise training in the fasted state may be relevant to patients with T2DM or IR. In healthy subjects, acute endurance exercise in the fasted state is accompanied by lower blood insulin and elevated blood free fatty acid concentrations, stable blood glucose concentrations (in the first 60-90 min), superior intramyocellular triacylglycerol oxidation and whole-body lipolysis, and muscle glycogen preservation. Long-term exercise training in the fasted state in healthy subjects is associated with greater improvements in insulin sensitivity, basal muscle fat uptake capacity, and oxidation. Therefore, promising results of exercise (training) in the fasted state have been found in healthy subjects on parameters of muscle biochemistry and metabolism linked to insulin sensitivity and glycemic control. Whether exercise training intervention in which exercise sessions are organized in the fasted state may be more effective in improving insulin sensitivity or glycemic control in T2DM patients and insulin-resistant individuals warrants investigation.

Beneficial Autophagic Activities, Mitochondrial Function, and Metabolic Phenotype Adaptations Promoted by High-Intensity Interval Training in a Rat Model

The effects of high-intensity interval (HIIT) and moderate-intensity continuous training (MICT) on basal autophagy and mitochondrial function in cardiac and skeletal muscle and plasma metabolic phenotypes have not been clearly characterized. Here, we investigated how 10-weeks HIIT and MICT differentially modify basal autophagy and mitochondrial markers in cardiac and skeletal muscle and conducted an untargeted metabolomics study with proton nuclear magnetic resonance (¹H NMR) spectroscopy and multivariate statistical analysis of plasma metabolic phenotypes. Male Sprague–Dawley rats were separated into three groups: sedentary control (SED), MICT, and HIIT. Rats underwent evaluation of exercise performance, including exercise tolerance and grip strength, and blood lactate levels were measured immediately after an incremental exercise test. Plasma samples were analyzed by ¹H NMR. The expression of autophagy and mitochondrial markers and autophagic flux (LC3II/LC3-I ratio) in cardiac, rectus femoris, and soleus muscle were analyzed by western blotting. Time to exhaustion and grip strength increased significantly following HIIT compared with that in both SED and MICT groups. Compared with those in the SED group, blood lactate level, and the expression of SDH, COX-IV, and SIRT3 significantly increased in rectus femoris and soleus muscle of both HIIT and MICT groups. Meanwhile, SDH and COX-IV content of cardiac muscle and COX-IV and SIRT3 content of rectus femoris and soleus muscle increased significantly following HIIT compared with that following MICT. The expression of LC3-II, ATG-3, and Beclin-1 and LC3II/LC3-I ratio were significantly increased only in soleus and cardiac muscle following HIIT. These data indicate that HIIT was more effective for improving physical performance and facilitating cardiac and skeletal muscle adaptations that increase mitochondrial function and basal autophagic activities. Moreover, ¹H NMR spectroscopy and multivariate statistical analysis identified 11 metabolites in plasma, among which fine significantly and similarly changed after both HIIT and MICT, while BCAAs isoleucine, leucine, and valine and glutamine were changed only after HIIT. Together, these data indicate distinct differences in specific metabolites and autophagy and mitochondrial markers following HIIT vs. MICT and highlight the value of metabolomic analysis in providing more detailed insight into the metabolic adaptations to exercise training.

Comparison of the inflammatory and stress response between sprint interval swimming and running

The aim of the study was to compare myocellular damage, metabolic stress, and inflammatory responses as well as circulating sodium (Na⁺ ) and potassium (K⁺ ) between a single sprint swimming and running training. Eighteen subjects regularly involved in swimming and running training for at least 2 years were recruited. The subjects performed 8 × 30 seconds "all out" exercise on different days either by running or by swimming in a random order. Blood was collected before each training session, after the cessation of exercise (post) and after 2 hours of rest (2 hours). We then analyzed tumor necrosis factor alpha (TNF-α), interleukin 10 (IL-10), interleukin 6 (IL-6), cortisol, creatine kinase MB isoform (CK-MB), lactate dehydrogenase (LDH), K⁺ , and Na⁺ . Neither TNF-α nor IL-10 differed between swimming and running. Most of the subjects showed a non-statistically significant increase of LDH and CK-MB after swimming. On the other hand, IL-6 (P < .05) and cortisol (P < .05) were significantly lower after 2 hours of swimming than after running. In addition, post-exercise K⁺ was significantly lower (P < .001) for swimming than for running. Our results provide evidence of similar inflammatory responses between exercise modes but lower metabolic stress in response to swimming than in response to running.

A pilot study comparing the metabolic profiles of elite-level athletes from different sporting disciplines

Background

The outstanding performance of an elite athlete might be associated with changes in their blood metabolic profile. The aims of this study were to compare the blood metabolic profiles between moderate- and high-power and endurance elite athletes and to identify the potential metabolic pathways underlying these differences.

Methods

Metabolic profiling of serum samples from 191 elite athletes from different sports disciplines (121 high- and 70 moderate-endurance athletes, including 44 high- and 144 moderate-power athletes), who participated in national or international sports events and tested negative for doping abuse at anti-doping laboratories, was performed using non-targeted metabolomics-based mass spectroscopy combined with ultrahigh-performance liquid chromatography. Multivariate analysis was conducted using orthogonal partial least squares discriminant analysis. Differences in metabolic levels between high- and moderate-power and endurance sports were assessed by univariate linear models.

Results

Out of 743 analyzed metabolites, gamma-glutamyl amino acids were significantly reduced in both high-power and high-endurance athletes compared to moderate counterparts, indicating active glutathione cycle. High-endurance athletes exhibited significant increases in the levels of several sex hormone steroids involved in testosterone and progesterone synthesis, but decreases in diacylglycerols and ecosanoids. High-power athletes had increased levels of phospholipids and xanthine metabolites compared to moderate-power counterparts.

Conclusions

This pilot data provides evidence that high-power and high-endurance athletes exhibit a distinct metabolic profile that reflects steroid biosynthesis, fatty acid metabolism, oxidative stress, and energy-related metabolites. Replication studies are warranted to confirm differences in the metabolic profiles associated with athletes’ elite performance in independent data sets, aiming ultimately for deeper understanding of the underlying biochemical processes that could be utilized as biomarkers with potential therapeutic implications.

Electronic supplementary material

The online version of this article (10.1186/s40798-017-0114-z) contains supplementary material, which is available to authorized users.

Metabolomics in Human Acute-Exercise Trials: Study Design and Preparation

Metabolomics can be of great value in the study of exercise metabolism. However, because of the high intraindividual and interindividual biological variability of the human metabolome, special considerations should be taken into account when designing an acute-exercise metabolomic study. To study different exercise parameters, e.g., different exercise modes, intensities, etc., a crossover study design, where each participant acts as their own control, is preferable to a parallel design, one involving different groups of participants. Moreover, the study should include a no exercise, control trial. Before each trial, participants should follow carefully designed preparatory steps to control for possible confounding factors, i.e., maintain repeatable and constant conditions for all individual trials of the study to minimize variation due to factors other than the one(s) being studied. This chapter focuses on the design of human metabolomic studies, where the intervention is an acute metabolic challenge, such as an exercise bout or a test meal, and presents some basic steps for screening potential participants, performing preliminary tests, preparing for the trial day, and performing the trial.

Omics and Exercise: Global Approaches for Mapping Exercise Biological Networks

The application of global "-omics" technologies to exercise has introduced new opportunities to map the complexity and interconnectedness of biological networks underlying the tissue-specific responses and systemic health benefits of exercise. This review will introduce major research tracks and recent advancements in this emerging field, as well as critical gaps in understanding the orchestration of molecular exercise dynamics that will benefit from unbiased omics investigations. Furthermore, significant research hurdles that need to be overcome to effectively fill these gaps related to data collection, computation, interpretation, and integration across omics applications will be discussed. Collectively, a cross-disciplinary physiological and omics-based systems approach will lead to discovery of a wealth of novel exercise-regulated targets for future mechanistic validation. This frontier in exercise biology will aid the development of personalized therapeutic strategies to improve athletic performance and human health through precision exercise medicine.

Apoptosis of T-Cell Subsets after Acute High-Intensity Interval Exercise

INTRODUCTION

High-intensity interval training (HIT) exercise has gained much interest in both performance and recreational sports. This study aims to compare the effect of HIT versus continuous (CONT) exercise with regard to changes of circulating T cells and progenitor cells.

METHODS

Subjects (n = 23) completed an HIT test and an isocaloric CONT test. Blood samples were collected before, immediately after, and 3 and 24 h postexercise for the assessment of low differentiated (CD3CD28CD57), highly differentiated T cells (CD3CD28CD57), regulatory T cells (Tregs) (CD4CD25CD127), hematopoietic progenitor cells (CD45CD34), and endothelial progenitor cells (CD45CD34KDR) by flow cytometry. The detection of apoptosis was performed by using labeling with annexin V. To analyze potential mechanisms affecting T cells, several hormones and metabolites were analyzed.

RESULTS

Both exercise tests induced an increase of catecholamines, cortisol, and thiobarbituric acid-reactive substances (P < 0.05). CONT induced a higher increase of apoptosis in low differentiated T cells compared with the HIT (CONT: 3.66% ± 0.21% to 6.48% ± 0.29%, P < 0.05; HIT: 3.43% ± 0.31% to 4.71% ± 0.33%), whereas HIT was followed by a higher rate of apoptotic highly differentiated T cells (CONT: 21.45% ± 1.23% to 25.32% ± 1.67%; HIT: 22.45% ± 1.37% to 27.12% ± 1.76%, P < 0.05). Regarding Tregs, HIT induced a mobilization, whereas CONT induced apoptosis in these cells (P < 0.05). The mobilization of progenitor cells did not differ between the exercise protocols.

CONCLUSION

These results suggest that HIT deletes mainly highly differentiated T cells known to affect immunity to control latent infections. By contrast, CONT deletes mainly low differentiated T cells and Tregs, which might affect defense against new infectious agents.

Metabolomics Approach in the Investigation of Metabolic Changes in Obese Men after 24 Weeks of Combined Training

Obesity is associated with comorbidities related to metabolic disorders due to excess of adipose tissue. Physical exercise has a major role in the prevention of obesity. Combined training (CT), in particular, has been shown to improve markers of health. In this study, we used ¹H NMR-based metabolomics to investigate changes in the metabolism of obese men after 24 weeks of CT. Twenty-two obese (body mass index 31 ± 1.4 kg/m²), middle-aged men (48.2 ± 6.1 years) were randomly assigned to a control group (CG, n = 11) or CT group (n = 11). The CT was performed three times a week (resistance and aerobic training) for 24 weeks. Blood samples were collected before and after experimental period. There was an improvement in body composition and physical fitness indices after CT training. Multivariate PCA and PLS-DA models showed a distinct separation between groups. Twenty metabolites with importance for projection (VIP) >1.0 were identified, and four were classified as best discriminators (tyrosine, 2-oxoisocaproate, histidine, pyruvate). Some metabolites were correlated with strength, VO₂ peak, fat and lean body mass, waist circumference, and insulin. In conclusion, 24 weeks of CT was effective for functional improvements and metabolic changes in obese middle-aged men.

Physical Exercise on Inflammatory Markers in Type 2 Diabetes Patients: A Systematic Review of Randomized Controlled Trials

Background. Type 2 diabetes mellitus (T2DM) is a serious disease associated with high morbidity and mortality. Scientific findings showed that physical exercise is an option for treatment of these patients. This study's objective is to investigate the effects of supervised aerobic and/or resistance physical training on inflammatory markers in subjects with T2DM. Methods. A systematic review was conducted on four databases, MEDLINE, CENTRAL, LILACS, and Scopus, and manual search from 21 to 30 November 2016. Randomized clinical trials involving individuals diagnosed with T2DM, who have undergone supervised training protocols, were selected in this study. Results. Eleven studies were included. Studies that evaluated control group versus aerobic exercise reported controversial results about the effectiveness of physical training in modifying C-reactive protein (CRP) and cytokine levels. The only variable analyzed by the six studies in comparison to the control group versus resistance exercise was CRP. This protein showed no significant difference between groups. Between the two modes of exercise (aerobic and resistance), only one study demonstrated that aerobic exercise was more effective in reducing CRP. Conclusion. The evidence was insufficient to prove that aerobic or resistance exercise improves systemic levels of inflammatory markers in patients with T2DM.