Acute Interval Exercise Research Articles

The effects of exercise on cognitive function and brain plasticity - a feasibility trial.

Exercise-mediated cognitive improvements can be at least partly attributed to neuroplastic changes in the nervous system, and may be influenced by the Val66Met polymorphism of the brain-derived neurotrophic factor (BDNF) gene. Transcranial magnetic stimulation (TMS) can be used to assess mechanisms of plasticity in humans noninvasively. To assess the feasibility of evaluating the effects of short-term regular exercise on cognitive performance, and to evaluate the relationship between these effects, TMS measures of plasticity, and BDNF Met carrier status in young healthy sedentary adults. Of the 19 participants who enrolled in the study, 14 sedentary adults (12 females, age mean±SD, 27±12.3 yr), with less than two sessions of physical exercise in the preceding 2 months, completed an aerobic exercise regimen including four 30-min daily sessions per week for 4 weeks (for a total of 16 sessions) delivered at 55-64% of age-predicted maximal heart rate. Prior to and following the exercise regimen, participants performed a neuropsychological test battery and an intermittent theta-burst TMS plasticity protocol. All participants completed the various measures and adhered to the exercise regimen. There were no complications and the results obtained were reliable. The feasibility of the approach is thus well established. Between-group comparisons of pre-post change revealed trends toward increased performance on the Stroop and faster reaction times in the CPT detectability in the Val66Val subgroup (p = 0.07 and p = 0.08), and a reduction in TBS-induced modulation of TMS responses in Met carriers (p = 0.07). Acute exercise interventions in sedentary adults can be meaningfully conducted along with cognitive and neurophysiologic measures to assess behavioral and neurobiological effects and assessment of BDNF polymorphism. TMS measures of plasticity can be used to evaluate the effects of exercise on brain plasticity, and relate them to neuropsychological measures of cognition.

The effect of acute exercise on blood concentrations of brain-derived neurotrophic factor in healthy adults: a meta-analysis.

It has been hypothesized that one mechanism through which physical activity provides benefits to cognition and mood is via increasing brain-derived neurotrophic factor (BDNF) concentrations. Some studies have reported immediate benefits to mood and various cognitive domains after a single session of exercise. This meta-analysis sought to determine the effect of a single exercise session on concentrations of BDNF in peripheral blood, in order to evaluate the potential role of BDNF in mediating the beneficial effects of exercise on brain health. MEDLINE, Embase, PsycINFO, SPORTDiscus, Rehabilitation & Sports Medicine Source, and CINAHL databases were searched for original, peer-reviewed reports of peripheral blood BDNF concentrations before and after acute exercise interventions. Risk of bias within studies was assessed using standardized criteria. Standardized mean differences (SMDs) were generated from random effects models. Risk of publication bias was assessed using a funnel plot and Egger's test. Potential sources of heterogeneity were explored in subgroup analyses. In 55 studies that met inclusion criteria, concentrations of peripheral blood BDNF were higher after exercise (SMD=0.59, 95% CI: 0.46-0.72, P<0.001). In meta-regression analysis, greater duration of exercise was associated with greater increases in BDNF. Subgroup analyses revealed an effect in males but not in females, and a greater BDNF increase in plasma than serum. Acute exercise increased BDNF concentrations in the peripheral blood of healthy adults. This effect was influenced by exercise duration and may be different across genders.

The repeatability of the abbreviated (4-h) Oral Fat Tolerance Test and influence of prior acute aerobic exercise

PurposeThe Oral Fat Tolerance Test (OFTT) is regarded as a repeatable measure used to assess postprandial triglyceride (TAG) levels, with higher levels observed in cardio-metabolic disorders. Acute aerobic exercise intervention before OFTT reduces the TAG response, but the repeatability of this effect is unknown. The aim of this study was to determine the repeatability of the abbreviated 4-h OFTT with and without immediate prior aerobic exercise.MethodsOn four separate days, healthy adult male participants underwent two 4-h OFTT (n = 10) and another two 4-h OFTT with 1-h of standardised moderate intensity aerobic exercise performed immediately before meal ingestion (n = 11). The OFTT meal composition included 75.4 g total fat, 21.7 g carbohydrate and 13.7 g protein. Venous blood was sampled at baseline and hourly up to 4 h after the OFTT meal ingestion, and TAG area under the curve (AUC) was calculated.ResultsNonparametric Bland–Altman analysis of 4-h TAG AUC revealed that 9 of 10 repeat measurements fell within ±15 % of the median TAG AUC for the OFTT. By contrast, two of 11 repeat measurements fell within ±15 % of the median TAG AUC for the OFTT undertaken with 1-h prior aerobic exercise.ConclusionsThe 4-h OFTT is a repeatable test of postprandial TAG responses in healthy men. However, aerobic exercise performed immediately before OFTT considerably increases the variability of TAG AUC. These findings have implications for interpretation of research studies investigating exercise intervention performed immediately before OFTT. Future studies should also investigate the repeatability of exercise performed 8–24 h before OFTT.

A perspective on the future role of brain pet imaging in exercise science

Positron Emission Tomography (PET) bears a unique potential for examining the effects of physical exercise (acute or chronic) within the central nervous system in vivo, including cerebral metabolism, neuroreceptor occupancy, and neurotransmission. However, application of Neuro-PET in human exercise science is as yet surprisingly sparse. To date the field has been dominated by non-invasive neuroelectrical techniques (EEG, MEG) and structural/functional magnetic resonance imaging (sMRI/fMRI). Despite PET having certain inherent disadvantages, in particular radiation exposure and high costs limiting applicability at large scale, certain research questions in human exercise science can exclusively be addressed with PET: The “metabolic trapping” properties of 18F-FDG PET as the most commonly used PET-tracer allow examining the neuronal mechanisms underlying various forms of acute exercise in a rather unconstrained manner, i.e. under realistic training scenarios outside the scanner environment. Beyond acute effects, 18F-FDG PET measurements under resting conditions have a strong prospective for unraveling the influence of regular physical activity on neuronal integrity and potentially neuroprotective mechanisms in vivo, which is of special interest for aging and dementia research. Quantification of cerebral glucose metabolism may allow determining the metabolic effects of exercise interventions in the entire human brain and relating the regional cerebral rate of glucose metabolism (rCMRglc) with behavioral, neuropsychological, and physiological measures. Apart from FDG-PET, particularly interesting applications comprise PET ligand studies that focus on dopaminergic and opioidergic neurotransmission, both key transmitter systems for exercise-related psychophysiological effects, including mood changes, reward processing, antinociception, and in its most extreme form ‘exercise dependence’. PET ligand displacement approaches even allow quantifying specific endogenous neurotransmitter release under acute exercise interventions, to which modern PET/MR hybrid technology will be additionally fruitful. Experimental studies exploiting the unprecedented multimodal imaging capacities of PET/MR in human exercise sciences are as yet pending.

The blood pressure response to acute and chronic aerobic exercise: A meta-analysis of candidate gene association studies.

To meta-analyze candidate gene association studies on the change in blood pressure beyond the immediate post-exercise phase after versus before aerobic exercise. Meta-analysis. A systematic search was conducted. Studies retrieved included acute (short-term or postexercise hypotension) or chronic (long-term or training) aerobic exercise interventions; and blood pressure measured before and after aerobic exercise training, or before and after exercise or control under ambulatory conditions by genotype. Effect sizes were determined for genotype and adjusted for sample features. Qualifying studies (k=17, n=3524) on average included middle-aged, overweight men (44.2%) and women (55.8%) with prehypertension (134.9±11.7/78.6±9.5mmHg). Training interventions (k=12) were performed at 60.4±12.9% of maximum oxygen consumption (VO2max) for 41.9±12.5minsession(-1), 3.6±1.2daysweek(-1) for 15.7±7.6week; and post-exercise hypotension interventions (k=5) were performed at 53.5±14.4% VO2max for 38.5±5.4minsession(-1). Sample characteristics explained 54.2-59.0% of the variability in the blood pressure change after versus before acute exercise or control under ambulatory conditions, and 57.4-67.1% of the variability in the blood pressure change after versus before training (p<0.001). Only angiotensinogen M235T (rs699) associated with the change in diastolic blood pressure after versus before training (R(2)=0.1%, p=0.05), but this association did not remain statistically significant after adjustment for multiple comparisons. Sample characteristics explained most of the variability in the change of BP beyond the immediate post-exercise phase after versus before acute and chronic aerobic exercise. Angiotensinogen M235T (rs699) was the only genetic variant that associated with the change in diastolic blood pressure after versus before training, accounting for <1% of the variance.

Basal and exercise induced label-free quantitative protein profiling of m. vastus lateralis in trained and untrained individuals

Morphological and metabolic adaptations of the human skeletal muscle to exercise are crucial to improve performance and prevent chronic diseases and metabolic disorders. In this study we investigated human skeletal muscle protein composition in endurance trained (ET) versus untrained individuals (UT) and its modulation by an acute bout of endurance exercise. Participants were recruited based on their VO2max and subjected to a bicycle exercise test. M. vastus lateralis biopsies were taken before and three hours after exercise. Muscle lysates were analyzed using off-gel LC-MS/MS. Relative protein abundances were compared between ET and UT at rest and after exercise. Comparing UT and ET, we identified 92 significantly changed proteins under resting conditions. Specifically, fiber-type-specific and proteins of the oxidative phosphorylation and tricarboxylic acid cycle were increased in ET. In response to acute exercise, 71 proteins in ET and 44 in UT were altered. Here, a decrease of proteins involved in energy metabolism accompanied with alterations of heat shock and proteasomal proteins could be observed. In summary, long-term endurance training increased the basal level of structural and mitochondrial proteins in skeletal muscle. In contrast, acute exercise resulted in a depletion of proteins related to substrate utilization, especially in trained athletes. Biological significanceThe investigation of the human skeletal muscle proteome in response to exercise may provide novel insights into the process of muscular plasticity. It is of importance in the development of exercise-based strategies in the prevention and therapy of many chronic inflammatory and degenerative diseases which are often accompanied by muscular deconditioning. Up to date, proteomic investigations of the human muscle proteome in adaptation to exercise are mainly focused on untrained individuals and often restricted to animal studies. In the present study we compare the protein composition in endurance trained athletes and untrained individuals in the resting muscle and its modulation in response to acute exercise. To our knowledge, we present the first comprehensive analysis of skeletal muscle proteome alterations in response to acute and long-term exercise intervention.

Acute exercise is associated with specific executive functions in college students with ADHD: A preliminary study

PurposeThe relationship between acute exercise and executive functions in college students with attention deficit hyperactivity disorder (ADHD) has not been clearly established. The purpose of this preliminary study was to examine the difference in cognitive performance between college students with and without ADHD and to explore the effects of acute exercise on multiple aspects of executive functions and on serum brain derived neurotrophic factor (BDNF). MethodsCollege students (normal: n = 10; ADHD: n = 10) performed the Stroop Test, Trail Making Test, and Digit Span Test prior to and after an acute exercise intervention. Blood samples were obtained prior to the pre-test cognitive test performance and then again after exercise and prior to the post-test cognitive test performance. ResultsStudents with ADHD exhibited impaired executive functions, particularly on inhibition. Additionally, while acute exercise improved all aspects of executive functions in those without ADHD, acute exercise only improved inhibitory performance for those with ADHD. Further, BDNF was not influenced by acute exercise regardless of the subjects' ADHD status. ConclusionThese results provide preliminary evidence for exercise as a potential adjunct treatment for benefitting inhibition in college students with ADHD.

Acute Exercise and Postprandial Lipemia in Young People

Exaggerated postprandial triacylglycerol concentrations (TAG) independently predict future cardiovascular events. Acute exercise and diet interventions attenuate postprandial TAG in adults. This paper aims to examine the exercise postprandial lipemia studies published to date in young people. Nine studies satisfied the inclusion criteria adopted for this summary. The majority of studies are in boys (22% girls) and have shown a single ~60-min session of moderate-intensity exercise, performed 12-18 hours before a standardized meal, reduces postprandial TAG. Manipulations of exercise duration and intensity suggest an exercise energy expenditure dose-dependent response is not supported directly in healthy young people. Studies investigating alternative exercise bouts have reported lower postprandial TAG after simulated intermittent games activity, high-intensity interval running and cumulative 10-min blocks over several hours, which may appeal to the spontaneous physical activity habits of young people. Although extension of these initial findings is warranted, exercise may be an effective strategy to promote regular benefits in TAG metabolism in children and adolescents; this may contribute to an improved cardiovascular disease risk profile early in life.

Identification of human exercise-induced myokines using secretome analysis

Endurance exercise is associated with significant improvements in cardio-metabolic risk parameters. A role for myokines has been hypothesized, yet limited information is available about myokines induced by acute endurance exercise in humans. Therefore, the aim of the study was to identify novel exercise-induced myokines in humans. To this end, we carried out a 1 h one-legged acute endurance exercise intervention in 12 male subjects and a 12 wk exercise training intervention in 18 male subjects. Muscle biopsies were taken before and after acute exercise or exercise training and were subjected to microarray-based analysis of secreted proteins (secretome). For acute exercise, secretome analysis resulted in a list of 86 putative myokines, which was reduced to 29 by applying a fold-change cut-off of 1.5. Based on that shortlist, a selection of putative myokines was measured in the plasma by ELISA or multiplex assay. From that selection, CX3CL1 (fractalkine) and CCL2 (MCP-1) increased at both mRNA and plasma levels. From the known myokines, only IL-6 and FGF 21 changed at the mRNA level, whereas none of the known myokines changed at the plasma level. Secretome analysis of exercise training intervention resulted in a list of 69 putative myokines. Comparing putative myokines altered by acute exercise and exercise training revealed a limited overlap of only 13 genes. In conclusion, this study identified CX3CL1 and CCL2 as myokines that were induced by acute exercise at the gene expression and plasma level and that may be involved in communication between skeletal muscle and other organs.

Acute interval exercise intensity does not affect appetite and nutrient preferences in overweight and obese males.

This study investigated the influence of two different intensities of acute interval exercise on food preferences and appetite sensations in overweight and obese men. Twelve overweight/obese males (age=29.0±4.1 years; BMI =29.1±2.4 kg/m2) completed three exercise sessions: an initial graded exercise test, and two interval cycling sessions: moderate-(MIIT) and high-intensity (HIIT) interval exercise sessions on separate days in a counterbalanced order. The MIIT session involved cycling for 5-minute repetitions of alternate workloads 20% below and 20% above maximal fat oxidation. The HIIT session consisted of cycling for alternate bouts of 15 seconds at 85% VO2max and 15 seconds unloaded recovery. Appetite sensations and food preferences were measured immediately before and after the exercise sessions using the Visual Analogue Scale and the Liking & Wanting experimental procedure. Results indicated that liking significantly increased and wanting significantly decreased in all food categories after both MIIT and HIIT. There were no differences between MIIT and HIIT on the effect on appetite sensations and Liking & Wanting. In conclusion, manipulating the intensity of acute interval exercise did not affect appetite and nutrient preferences.

Chronic exercise expenditure and compensatory behaviours in adolescent girls. A feasibility study

Partial dietary intake compensation for chronic exercise energy expenditure has been reported in adults, but not included measures of free-living physical activity. Acute exercise interventions in young people have not identified meaningful compensatory behaviour. Therefore, it is important to examine the effect of a chronic exercise programme on energy balance and compensation in young people. This is particularly pertinent given the current prevalence in paediatric obesity and an imbalance between physical activity and sedentary activities in this population. Six low active adolescent girls (age 12.7(0.7) years, BMI 20.8(3.8) kg m−2) completed a 6 week supervised exercise programme (3 × 30 min moderate intensity sessions wk−1). Measures of dietary energy intake, free-living physical activity energy expenditure and energy balance were compared before and immediately after the supervised exercise programme. Mean group changes for energy intake and energy balance (−0.41 and 0.01 MJ, respectively) were not meaningful, but total energy expenditure demonstrated a moderate effect (−0.52 MJ, ES = 0.52). However, examination of individual’s results provided greater insight and suggested variation in measures underpinned by compensatory behaviours were apparent, with two girls compensating. This small feasibility study showed it may be possible to estimate the complex interaction of free-living energy expenditure and energy intake in adolescent girls, but the accuracy of the measurements must improve. The results warrant further study with a larger sample to extend our understanding of exercise-induced compensatory behaviour that may occur at an individual level. Supported by a Tanita Healthy Weight Community Grant.

The effects of exercise on vaccination responses: A review of chronic and acute exercise interventions in humans

Vaccination programs, although feted for success in reducing infectious disease morbidity and mortality, are limited by vaccine efficacy, which is particularly problematic in populations with reduced immune function. Exercise has been identified as a behavioural factor that can improve immune function in some settings and cohorts, and therefore, in the setting of vaccination, it may serve as an adjuvant for immune responses. Here, we summarise the body of evidence that has investigated the effects of chronic or acute exercise interventions on vaccination responses. A systematic search of the literature was conducted including six major databases. Randomised control trials (RCTs), cross-sectional and observational studies that involved a variety of population samples and that employed any modality or intensity of acute exercise or chronic training prior to vaccine administration and measured any immune response were included. Twenty trials met the inclusion criteria for this review. Nine studies investigated the effect of acute exercise on the immune response to vaccination, whilst the remaining eleven studies investigated the effect of chronic exercise. Most of the current published literature suggests that exposure to either acute or chronic exercise significantly augments the immune response to vaccination. The clinical importance of this adjuvant action of exercise, if any, as well as variability in responsiveness across different cohorts, dose-response relationships and the optimal exercise modality to employ for this indication deserve further study.

Satellite cell pool size expansion is affected by skeletal muscle characteristics

The purpose of this study was to determine the change of satellite cells (SC) pool size after an acute bout of strenuous exercise and to determine whether this is affected by baseline SC count and fiber type.Participants completed 40min (5 × 8 bouts, 2 min rest) downhill running (DHR) at 80% VO2max at −10% gradient. Muscle biopsy was taken a week before VO2max test and 7–9 days after DHR. Delayed onset muscle soreness (DOMS) and creatine kinase activities (CK) were measured on d1, d2 d7, and d9 after the DHR bout. Satellite cells were analyzed with Pax7 and laminin immunohistochemistry staining.DOMS and CK increased 1 day after DHR (P &lt; 0.01) and returned to baseline. SC pool size was increased by 26% 7–9 days after the exercise intervention (P = 0.005). SC count after the acute exercise intervention was significantly correlated with VO2max (P = 0.03). A trend was seen in correlation between change in SC and percentage MHC type II (P = 0.10).This study reports that 7–9 days after a single bout of DHR, the SC pool expands and the expansion extent is associated with inter‐individual physiological characteristics: VO2max and with a tendency, skeletal muscle fiber type.Grant Funding Source : Claude Leon Foundation, NRF (National Research Foundation)

The Role of Prostaglandin F&lt;sub&gt;2α&lt;/sub&gt; in Skeletal Muscle Regeneration

Prostaglandins are a diverse group of eicosanoid hormones that modulate various processes, many of which are related to inflammation. Due to this, prostaglandins are the target of cyclooxygenase (COX) inhibitor drugs. Prostaglandin F2α (PGF2α) mediates processes integral to successful skeletal muscle regeneration, roles elucidated through suppression of its production with various COX-inhibitors. Objective: To provide a comprehensive review of literature regarding roles for the COX-metabolite PGF2α in skeletal muscle regeneration and consequences of its suppression with COX-inhibitors. Design: Systematic review. Method: Recognition was given to early in vitro studies that first established roles for PGF2α in two specific regenerative processes, and attention was then directed to human experiments investigating the PGF2α response to aerobic and resistance exercise. Results: PGF2α mediates protein synthesis and satellite cell activity post-injury. Although methodological differences exist between experiments, research has unanimously demonstrated COX-mediated suppression of PGF2α diminishes these regenerative processes. Conclusions: All experiments in humans have been acute exercise interventions. Studies involving repeated exercise and repeated administration of COX-inhibitors seem warranted to determine if chronic use impedes skeletal muscle regeneration after exercise. Such a finding may hold serious implications for recreational athletes, patients, and clinicians managing musculoskeletal pain or diseases with regular use of COX-inhibitors.

A systematic review of exercise as a therapeutic intervention to improve arterial function in persons living with spinal cord injury

All randomized controlled trials, prospective cohort, case-controlled, pre-post studies and case reports that assessed exercise interventions, which influence arterial structure and function after spinal cord injury (SCI), were included. To review systematically the evidence for exercise as a therapy to alter arterial function in persons with SCI. Literature searches were conducted for appropriate articles using several electronic databases (e.g. MEDLINE, EMBASE). Three independent reviewers evaluated each investigation's quality, using the Physiotherapy Evidence Database Scale for randomized controlled trials and Downs and Black Scale for all other studies. Results were tabulated and levels of evidence assigned. A total of 283 studies were found through the systematic literature search. Upon review of the articles, 27 were included. The articles were separated into those investigating arterial benefits, resulting from either acute bouts of exercise or long-term exercise interventions. The ability of both acute and long-term exercise interventions to improve arterial structure and function in those with SCI was supported by limited to moderate methodological quality. Upper body wheeling is the most commonly examined exercise therapy for improving arterial function. It appears from the evidence that a variety of exercise interventions, including passive exercise, upper body wheeling, functional electrical stimulation and electrically stimulated resistance exercise, can improve arterial function in those living with SCI. Although the quality and volume of evidence is low, the literature supports exercise as a useful intervention technique for improving arterial function in those with SCI.

Neuroplasticity – Exercise-Induced Response of Peripheral Brain-Derived Neurotrophic Factor

Exercise is known to induce a cascade of molecular and cellular processes that support brain plasticity. Brain-derived neurotrophic factor (BDNF) is an essential neurotrophin that is also intimately connected with central and peripheral molecular processes of energy metabolism and homeostasis, and could play a crucial role in these induced mechanisms. This review provides an overview of the current knowledge on the effects of acute exercise and/or training on BDNF in healthy subjects and in persons with a chronic disease or disability. A systematic and critical literature search was conducted. Articles were considered for inclusion in the review if they were human studies, assessed peripheral (serum and/or plasma) BDNF and evaluated an acute exercise or training intervention. Nine RCTs, one randomized trial, five non-randomized controlled trials, five non-randomized non-controlled trials and four retrospective observational studies were analysed. Sixty-nine percent of the studies in healthy subjects and 86% of the studies in persons with a chronic disease or disability, showed a 'mostly transient' increase in serum or plasma BDNF concentration following an acute aerobic exercise. The two studies regarding a single acute strength exercise session could not show a significant influence on basal BDNF concentration. In studies regarding the effects of strength or aerobic training on BDNF, a difference should be made between effects on basal BDNF concentration and training-induced effects on the BDNF response following an acute exercise. Only three out of ten studies on aerobic or strength training (i.e. 30%) found a training-induced increase in basal BDNF concentration. Two out of six studies (i.e. 33%) reported a significantly higher BDNF response to acute exercise following an aerobic or strength training programme (i.e. compared with the BDNF response to an acute exercise at baseline). A few studies of low quality (i.e. retrospective observational studies) show that untrained or moderately trained healthy subjects have higher basal BDNF concentrations than highly trained subjects. Yet, strong evidence still has to come from good methodological studies. Available results suggest that acute aerobic, but not strength exercise increases basal peripheral BDNF concentrations, although the effect is transient. From a few studies we learn that circulating BDNF originates both from central and peripheral sources. We can only speculate which central regions and peripheral sources in particular circulating BDNF originates from, where it is transported to and to what purpose it is used and/or stored at its final destination. No study could show a long-lasting BDNF response to acute exercise or training (i.e. permanently increased basal peripheral BDNF concentration) in healthy subjects or persons with a chronic disease or disability. It seems that exercise and/or training temporarily elevate basal BDNF and possibly upregulate cellular processing of BDNF (i.e. synthesis, release, absorption and degradation). From that point of view, exercise and/or training would result in a higher BDNF synthesis following an acute exercise bout (i.e. compared with untrained subjects). Subsequently, more BDNF could be released into the blood circulation which may, in turn, be absorbed more efficiently by central and/or peripheral tissues where it could induce a cascade of neurotrophic and neuroprotective effects.

Similar Expression of Oxidative Genes after Interval and Continuous Exercise

There is a debate whether interval or traditional endurance training is the most effective stimulus of mitochondrial biogenesis. Here, we compared the effects of acute interval exercise (IE) or continuous exercise (CE) on the muscle messenger RNA (mRNA) content for several genes involved in mitochondrial biogenesis and lipid metabolism. Nine sedentary subjects cycled for 90 min with two protocols: CE (at 67% VO2max) and IE (12 s at 120% and 18 s at 20% of VO2max). The duration of exercise and work performed with CE and IE was identical. Muscle biopsies were taken before and 3 h after exercise. There were no significant differences between the two exercise protocols in the increases in VO2 and HR, the reduction in muscle glycogen (35%-40% with both protocols) or the changes in blood metabolites (lactate, glucose, and fatty acids). The mRNA content for major regulators of mitochondrial biogenesis [peroxisome proliferator-activated receptor (PPAR) gamma coactivator 1alpha (PGC-1alpha), PGC-1-related coactivator, PPARbeta/delta] and of lipid metabolism [pyruvate dehydrogenase kinase isozyme 4 (PDK4)] increased after exercise, but there was no significant difference between IE and CE. However, the mRNA content for several downstream targets of PGC-1alpha increased significantly only after CE, and mRNA content for nuclear respiratory factor 2 was significantly higher after CE (P < 0.025 vs IE). The present findings demonstrate that, when the duration of exercise and work performed is the same, IE and CE influence the transcription of genes involved in oxidative metabolism in a similar manner.

The effects of vaccine timing on the efficacy of an acute eccentric exercise intervention on the immune response to an influenza vaccine in young adults

An acute bout of exercise prior to vaccination can improve the antibody and cell-mediated responses to influenza vaccination. The mechanisms underpinning this adjuvant effect remain unclear, and further investigation to determine the optimal exercise protocol is warranted. The aim of the current study was to determine whether exercise augmented the immune response to vaccination, and whether the timing of exercise relative to vaccination affected the efficacy of the intervention. One hundred and fifty-six (76 men) healthy participants were randomly assigned to a control group or one of three intervention groups who exercised immediately, 6 h or 48 h prior to administration of a standard trivalent influenza vaccine. The exercise groups performed 50 repetitions of the eccentric portion of both the bicep curl and lateral raise movements at an intensity eliciting 85% of each participant’s pre-determined concentric one repetition maxima. Antigen-specific serum antibody titres were measured at baseline and 28 days post-vaccination as indicators of the humoral response. All three viral strains elicited strong antibody responses; however, eccentric exercise did not further augment any antibody responses compared to the control group. Cell-mediated immunity at 28 days post-vaccination was determined by measuring the IFN-γ response to in vitro stimulation of the blood with whole vaccine. There were no differences in cell-mediated immunity among the groups. Although these null findings were unexpected, they are consistent with previous research showing that exercise-induced immunoenhancement was only observed when the control group had relatively poor responses. In conclusion, it is likely that the robust immune responses to the vaccine observed in this study may have limited any further immune enhancement by exercise.

Molecular responses to high-intensity interval exerciseThis paper is one of a selection of papers published in this Special Issue, entitled 14th International Biochemistry of Exercise Conference – Muscles as Molecular and Metabolic Machines, and has undergone the Journal’s usual peer review process.

From a cell-signaling perspective, short-duration intense muscular work is typically associated with resistance training and linked to pathways that stimulate growth. However, brief repeated sessions of high-intensity interval exercise training (HIT) induce rapid phenotypic changes that resemble traditional endurance training. Given the oxidative phenotype that is rapidly upregulated by HIT, it is plausible that metabolic adaptations to this type of exercise could be mediated in part through signaling pathways normally associated with endurance training. A key controller of oxidative enzyme expression in skeletal muscle is peroxisome proliferator-activated receptor gamma coactivator 1alpha (PGC-1alpha), a transcriptional coactivator that serves to coordinate mitochondrial biogenesis. Most studies of acute PGC-1alpha regulation in humans have used very prolonged exercise interventions; however, it was recently shown that a surprisingly small dose of very intense interval exercise, equivalent to only 2 min of all-out cycling, was sufficient to increase PGC-1alpha mRNA during recovery. Intense interval exercise has also been shown to acutely increase the activity of signaling pathways linked to PGC-1alpha and mitochondrial biogenesis, including AMP-activated protein kinase (alpha1 and alpha2 subunits) and the p38 mitogen-activated protein kinase. In contrast, signaling pathways linked to muscle growth, including protein kinase B/Akt and downstream targets p70 ribosomal S6 kinase and 4E binding protein 1, are generally unchanged after acute interval exercise. Signaling through AMP-activated protein kinase and p38 mitogen-activated protein kinase to PGC-1alpha may therefore explain, in part, the metabolic remodeling induced by HIT, including mitochondrial biogenesis and an increased capacity for glucose and fatty acid oxidation.

Gln27Glu polymorphism in the beta2 adrenergic receptor gene and lipid metabolism during exercise in obese women.

The Glu27Glu genotype in the beta-2-adrenergic receptor (ADRB2) is associated with fat mass, body mass index and obesity in females. In our population, we previously found an association of higher body mass index (BMI) among women who reported more physical activity and carried the Glu27 allele as compared to non carriers with the same level of activity. To examine the lipid metabolism differences, both at rest and during submaximal exercise in ADRB2 Glu27Glu vs Gln27Gln obese women. Eight obese women with the Glu27Glu genotype (age, 43+/-5 y; body mass index (BMI), 31.7+/-0.9 kg/m(2); percentage fat mass, 42.0+/-1.3; WHR, 0.83+/-0.02; and VO(2max), 21.6+/-0.9 ml/kg/min) were compared with seven obese women with the Gln27Gln genotype (age, 43+/-5 y; BMI, 33.9+/-1.3 kg/m(2); percentage fat mass, 41.6+/-1.2; WHR, 0.83+/-0.02; and VO(2max), 20.6+/-0.8 ml/kg/min). The ADRB2 polymorphism was identified by PCR-RFLP. Respiratory quotient was determined by indirect calorimetry at baseline, during 1 h of walking on a treadmill and 1 h after the exercise. Plasma triglycerides, glycerol, FFA, hydroxybutyrate, glucose and lactate were assayed by spectrophotometric methods. Insulin, leptin and progesterone were measured by radioimmunoassay. Adrenaline and noradrenaline were quantified by high performance liquid chromatography. The ADRB2 Glu27Glu subjects had lower plasma glycerol (P=0.047) and lower hydroxybutyrate (P=0.001) throughout the study than the Gln27Gln group. Plasma triglycerides (P=0.001), lactate (P<0.05) and serum insulin (P<0.05) remained higher in the Glu27Glu group vs the Gln27Gln group. The respiratory quotient (RQ) was higher in the Glu27Glu obese women along the study (P=0.046), and fat oxidation was significantly lower in this group during the recovery (P=0.048). The other variables did not differ statistically between groups. These data suggest that both lipolysis and fat oxidation promoted by an acute submaximal exercise intervention could be blunted in the polymorphic ADRB2 Glu27Glu group of our female obese population.