Min Post Exercise Research Articles

Kinetics of Immune Cell Mobilization during Acute Aerobic Exercise in Healthy Adults.

While pre-post differences in immune cell mobilization after acute aerobic exercise are well investigated, less is known about when and to what extent immune cells are mobilized during acute aerobic exercise. This experimental trial aimed to investigate the detailed kinetics of circulating immune cells in twelve healthy adults (n=6 females) who completed a 40-min aerobic exercise bout at 60% of the participants' V̇O2peak on a bicycle ergometer. Cellular inflammation markers and sex-dependent differences in circulating immune cells were analyzed. Blood samples were taken immediately before, after warm-up, during exercise after 5 min, 10 min, 15 min, 30 min, 40 min (cessation), and 60 min post exercise. Significant increases in leukocytes (p<0.001), lymphocytes (p<0.001), neutrophils (p=0.003) and platelets (p=0.047) can be observed after 5 min of exercise. The cellular inflammation markers show significant alterations only post exercise. Significant sex differences were observed for neutrophils (p=0.049) and neutrophil-to-lymphocyte ratio (p=0.007) one hour post exercise. These results indicate that i) leukocytes are already mobilized after 5 min of moderate-to-vigorous aerobic exercise, ii) the magnitude of exercise induced leukocyte mobilization is dependent on exercise duration, iii) integrative cellular inflammation markers are only altered after exercise cessation, and iv) the observed effects might be sex-dependent.

Blood-Based Markers for Skeletal and Cardiac Muscle Function in Eventing Horses before and after Cross-Country Rides and How They Are Influenced by Plasma Volume Shift.

Horses competing in cross-country tests are subjected to high physical demands. Within the scope of this prospective longitudinal study, blood values of 20 elite eventing horses were examined before and after two- to four-star cross-country rides. The aim was to find out whether blood-based markers for skeletal muscle and cardiac muscle function change after cross-country exercise. Parameters that provide information about fluid balance, muscle enzymes, metabolites and cardiac muscle-specific markers were investigated. We developed an approach to eliminate the concentration changes caused by reduced plasma volume. Parameters were measured pre, 10 and 30 min post exercise and the next morning and were evaluated using a mixed model. Thirty minutes after exercise, most parameter concentrations changed in an exercise-dependent manner. The next morning, most exercise-related markers recovered rapidly, while creatine kinase (CK) (26% increase; p = 0.008) and lactate dehydrogenase (LDH) (15% increase; p < 0.001) showed a declining but sustained increase. Cardiac troponin I (cTnI) increased above the reference range in 40 of the 55 rides (73%) and in 18 of 20 horses in the morning after exercise.

A Mango Leaf Extract (Zynamite®) Combined with Quercetin Has Exercise-Mimetic Properties in Human Skeletal Muscle

Zynamite PX®, a mango leaf extract combined with quercetin, enhances exercise performance by unknown molecular mechanisms. Twenty-five volunteers were assigned to a control (17 males) or supplementation group (8 males, receiving 140 mg of Zynamite® + 140 mg quercetin/8 h for 2 days). Then, they performed incremental exercise to exhaustion (IE) followed by occlusion of the circulation in one leg for 60 s. Afterwards, the cuff was released, and a 30 s sprint was performed, followed by 90 s circulatory occlusion (same leg). Vastus lateralis muscle biopsies were obtained at baseline, 20 s after IE (occluded leg) and 10 s after Wingate (occluded leg), and bilaterally at 90 s and 30 min post exercise. Compared to the controls, the Zynamite PX® group showed increased basal protein expression of Thr287-CaMKIIδD (2-fold, p = 0.007) and Ser9-GSK3β (1.3-fold, p = 0.005) and a non-significant increase of total NRF2 (1.7-fold, p = 0.099) and Ser40-NRF2 (1.2-fold, p = 0.061). In the controls, there was upregulation with exercise and recovery of total NRF2, catalase, glutathione reductase, and Thr287-CaMKIIδD (1.2–2.9-fold, all p &lt; 0.05), which was not observed in the Zynamite PX® group. In conclusion, Zynamite PX® elicits muscle signaling changes in resting skeletal muscle resembling those described for exercise training and partly abrogates the stress kinases responses to exercise as observed in trained muscles.

Intense interval exercise induces lactate accumulation and a greater suppression of acylated ghrelin compared with submaximal exercise in middle-aged adults.

Exercise in young adults (18-25 yr) suppresses appetite in a dose-response relationship with exercise intensity. Although several mechanisms have been proposed to explain this response, lactate is the most well established. To date, no study has investigated this specifically in middle-aged adults where the appetite response to a meal is different. To explore the effects of submaximal, near maximal, and supramaximal intensity exercise on appetite regulation in middle-aged adults. Nine participants (age: 45 ± 10 yr) completed four experimental sessions: 1) no-exercise control (CTRL); 2) moderate-intensity continuous training [MICT; 30 min, 65% maximal oxygen consumption (V̇o2max)]; 3) high-intensity interval training (HIIT; 10 × 1 min efforts, 90% heart rate maximum, 1 min recovery); and 4) sprint interval training (SIT; 8 × 15 s "all-out" efforts, 2 min recovery). Acylated ghrelin, active glucagon-like peptide-1 (GLP-1), active peptide tyrosine tyrosine (PYY), lactate, and subjective appetite perceptions were measured pre-exercise, 0-, 30-, and 90-min postexercise. Energy intake was recorded the day before and day of each session. Acylated ghrelin was suppressed (P < 0.001, [Formula: see text] = 0.474) by HIIT (0-min and 30-min postexercise; P < 0.091, d > 1.84) and SIT (0-min, 30-min, and 90-min postexercise; P < 0.037, d > 1.72) compared with CTRL, and SIT suppressed concentrations compared with MICT (0-min and 30-min postexercise; P < 0.91, d > 1.19). There were no effects of exercise on active PYY, active GLP-1, appetite perceptions, or free-living energy intake (P > 0.126, [Formula: see text] < 0.200). Intense interval exercise that generates lactate accumulation suppresses acylated ghrelin with little effect on anorexigenic hormones, overall appetite, or free-living energy intake.NEW & NOTEWORTHY We explored the effects of submaximal, near maximal, and supramaximal intensity exercise on appetite regulation in middle-aged adults. Our data support the intensity-dependent effect of exercise on acylated ghrelin suppression that is closely related to lactate accumulation, though there appears to be little effect on anorexigenic hormones [active peptide tyrosine tyrosine (PYY), active glucagon-like peptide-1 (GLP-1)], overall appetite, or free-living energy intake. These data support previous results in younger adults where lactate was implicated in the exercise-induced suppression of acylated ghrelin.

Resistance exercise acutely elevates dynamic cerebral autoregulation gain.

Dynamic cerebral autoregulation (dCA) describes the regulation of cerebral blood flow (CBF) in response to fluctuations in systemic blood pressure (BP). Heavy resistance exercise is known to induce large transient elevations in BP, which are translated into perturbations of CBF, and may alter dCA in the immediate aftermath. This study aimed to better quantify the time course of any acute alterations in dCA after resistance exercise. Following familiarisation to all procedures, 22 (14 male) healthy young adults (22 ± 2 years) completed an experimental trial and resting control trial, in a counterbalanced order. Repeated squat-stand manoeuvres (SSM) at 0.05 and 0.10 Hz were used to quantify dCA before, and 10 and 45 min after four sets of ten repetition back squats at 70% of one repetition maximum, or time matched seated rest (control). Diastolic, mean and systolic dCA were quantified by transfer function analysis of BP (finger plethysmography) and middle cerebral artery blood velocity (transcranial Doppler ultrasound). Mean gain (p = 0.02; d = 0.36) systolic gain (p = 0.01; d = 0.55), mean normalised gain (p = 0.02; d = 0.28) and systolic normalised gain (p = 0.01; d = 0.67) were significantly elevated above baseline during 0.10 Hz SSM 10-min post resistance exercise. This alteration was not present 45 min post-exercise, and dCA indices were never altered during SSM at 0.05 Hz. dCA metrics were acutely altered 10 min post resistance exercise at the 0.10 Hz frequency only, which indicate changes in the sympathetic regulation of CBF. These alterations recovered 45 min post-exercise.

A study of post exercise hypotension in normotensive offspring of hypertensives after acute exercise.

Post exercise hypotension (PEH) is a well-known entity in hypertensive and borderline hypertensive patients. Since the results are inconsistent in normotensives and there is a genetic predisposition of the individuals to hypertension, we hypothesized that PEH is expected to occur in those normotensives who are offspring of hypertensive parents. In this study, we therefore aimed to compare the magnitude of PEH after an acute bout of moderate intensity continuous exercise (MICE) in the offspring of hypertensives vs. offspring of normotensives. Sixty normotensive participants of both genders (male and female in equal proportion), aged 18-40 yr, were divided into two groups based on their family history of hypertension. The cases (Group 1, n=30) consisted of the normotensives who were offspring of hypertensive parents while the normotensives who were offspring of normotensive parents were taken as the controls (Group 2, n=30). The hypertensive patients were excluded from the study. The individuals underwent a control session (sitting at rest for 5-10 min), followed by a single acute bout of MICE based on the target heart rate (60-70% of maximum heart rate) on a treadmill at the same time of the day (in the morning). The pre- and post-exercise measurements (after 10 min post exercise) of systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MAP) were taken in all the participants using mercury sphygmomanometer in sitting position on the left arm. The intergroup and intragroup net effects of exercise on BP were compared with P<0.05 considered significant. The mean SBP was reduced by 5 mmHg than the baseline in the offspring of hypertensives (cases) as compared to the controls after exercise (P=0.01). The fall in mean DBP and MAP was insignificant across both the groups, but the magnitude of PEH measured as delta changes (BP before and after exercise) in SBP (~5 mmHg) and MAP (~4 mmHg) were significantly higher for the cases as compared to the controls (P=0.01). PEH occurs in higher magnitude in normotensives who are genetically predisposed to hypertension, such as offspring of hypertensive parents, and may find regular exercise-induced PEH as an important primary preventive tool to prevent or delay the development of hypertension.

Acute effect of high-intensity interval training versus moderate-intensity continuous training on appetite perception: A systematic review and meta-analysis

Interval training protocols have gained popularity over the years, but their impact on appetite sensation compared to officially recommended training method, moderate intensity continuous training (MICT) is not well understood. Thus, this systematic review and meta-analysis aimed to compare a single session of high intensity interval training (HIIT) including sprint interval training (SIT) with MICT on appetite perception measured by the visual analog scale (VAS). After searching up articles published up to September 2021, 13 randomized controlled studies were included in the meta-analysis. Outcomes of meta-analysis demonstrated that both acute sessions of HIIT/SIT and MICT suppressed appetite compared to no-exercise control groups immediately post exercise but there were no significant effects 30–90 min post exercise or in AUC values, indicating a transient effect of exercise on appetite sensations. Moreover, differences in appetite sensations between HIIT/SIT and MICT were negligible immediately post exercise, but HIIT/SIT suppressed hunger (MD = −6.347 [-12.054, −0.639], p = 0.029) to a greater extent than MICT 30- to 90-min post exercise, while there was a lack of consistency other VAS subscales of appetite. More studies that address the impact of exercising timing, nutrient compositions of energy intake (energy intake (EI)) and differences in participants’ characteristics and long-term studies analyzing chronic effects are needed to comprehensively examine the differences between HIIT/SIT and MICT on appetite and EI. Systematic Review Registration[https://www.crd.york.ac.uk/PROSPERO], Identifier [CRD42021284898].

Peripheral fatigue and hormone responses to branched-chain amino acids ingestion and exercise in recovery: a systematic review and meta-analysis.

Branched-chain amino acid (BCAA) can boost anabolism through an increase in the internal concentration of BCAA, which leads to facilitating anabolic hormone release to stimulate the power of the muscles. Studies on administration of BCAA to minimize fatigue substances during long periods of high intensity exercise have been conducted. However, there are disagreements concerning the results of these studies. A comprehensive search was performed on electronic databases up to November 2021 for trials evaluating the effects of BCAA on recovery following exercise. Mean ± standard deviation of follow-up cortisol, insulin, ammonia, and lactate concentrations were extracted to calculate the effect size for meta-analysis. A total of 146 participants for cortisol and 279 participants for lactate were found from the 7 and 15 studies, respectively. The results revealed a significant effect of BCAA supplementation on cortisol concentration during 120≤ min post exercise follow-up. Moreover, without considering follow-up times, an overall analysis showed that BCAA was effective in reducing blood lactate in aerobic exercise and the trained status of athletes. The advantages of BCAA administration relate to a reduction in cortisol concentration after 2h and ameliorated muscle function because of a probable attenuation of fatigue substances immediately after exercise.

Effects of Dominance and Sprint Interval Exercise on Testosterone and Cortisol Levels in Strength-, Endurance-, and Non-Training Men.

Simple SummaryExercise is a powerful stimulus to the endocrine system, modifying plasma concentrations of many hormones, including testosterone and cortisol, which are often used to describe fatigue in sport. In our investigation, we wanted to explore the hormonal response (testosterone and cortisol) in saliva after acute exercises in men who perform endurance-training and strength-training exercises compared to a non-training group. Participants performed sprint interval exercise. During the whole exercise, the participants’ heart rates were measured, and a rating of perceived exertion was assessed immediately after each bout. The study showed that there were no differences in testosterone and cortisol changes in the endurance-training, strength-training, and non-training groups after the sprint interval exercise. We suppose that one session of the sprint interval training should have more volume (more or longer duration of sprints) to provoke testosterone and cortisol reaction in endurance-training and strength-training individuals. However, the heart rates after acute exercise in the endurance-training and strength-training groups were lower than in participants from the non-training group.The aim of the study was to investigate the response of testosterone and cortisol to sprint interval exercises (SIEs) and to determine the role of dominance. The experiment was conducted in a group of 96 men, divided into endurance-training, strength-training, and non-training groups. Participants performed SIEs consisting of 5 × 10-s all-out bouts with a 50-s active recovery. Using the passive drool method, testosterone and cortisol concentrations were measured in saliva samples at rest at 10 min pre and 12 min post exercise. Participants’ heart rate (HR) was measured during the whole exercise. Dominance was assessed by the participants before the study; the rating of perceived exertion (RPE) was measured immediately after each bout. The study showed that those who trained in endurance and strength sports had significantly lower mean HRs after five acute 10-s interval bouts than those in the non-training group (p = 0.006 and p = 0.041, respectively). Dominance has an inverse relation to changes in HR; however, it has no relation to hormone response. No significant differences were observed in testosterone and cortisol changes in the endurance-training, strength-training, and non-training groups after SIE (p > 0.05), which may indicate that the exercise volume was too low.

Effect of Differing Durations of High-Intensity Intermittent Activity on Cognitive Function in Adolescents.

Exercise duration may influence the acute effects on cognition. However, only one study to date has explored the dose-response relationship between exercise duration and cognition in adolescents. Thus, the purpose of this study was to investigate the effect of differing durations of high-intensity intermittent running on cognition in adolescents. Thirty-eight adolescents (23 girls) completed three trials separated by 7 d: 30 min exercise, 60 min exercise, and rest; in a randomised crossover design. The exercise was a modified version of the Loughborough Intermittent Shuttle Test (LIST), which elicited high-intensity intermittent exercise. Cognitive function tests (Stroop test, Sternberg paradigm, Flanker task) were completed 30 min pre, immediately post, and 45 min post exercise. Response times on the incongruent level of the Flanker task improved to a greater extent 45 min following the 30 min LIST, compared to rest (p = 0.009). Moreover, response times improved to a greater extent on the three-item level of Sternberg paradigm 45 min following the 30 min LIST, compared to the 60 min LIST (p = 0.002) and rest (p = 0.013), as well as on the five-item level 45 min following the 30 min LIST, compared to the 60 min LIST (p = 0.002). In conclusion, acute exercise enhanced subsequent cognition in adolescents, but overall, 30 min of high-intensity intermittent running is more favourable to adolescents’ cognition, compared to 60 min.

The Effect Of Relative Intensity On The Magnitude And Duration Of Analgesia Following Acute Exercise

Exercise (EX) induced analgesia has been previously identified. However, the EX prescription necessary to elicit analgesia is not consistent. Additionally, the duration of the analgesic effect following EX bouts is unknown. PURPOSE: To determine the effect of EX intensity on the duration of EX induced analgesia. Secondly, to quantify the duration of EX induced analgesia following an acute bout of cycling. METHODS: Ten college aged students (4 men; 6 women; age = 20.1 ± 3.1 yrs) underwent 30 minutes of EX on a cycle ergometer. Following 5 minutes of light cycling (3-4 METS) each subject underwent 20 minutes of cycling at 8 METS followed by a 5-minute cooldown. Workload was titrated to ensure each subject could finish the EX session. Following the EX, each subject remained seated on the cycle for an additional 15 minutes. Oxygen consumption (VO2) was measured throughout the EX and recovery period. Minimal pain threshold (MPT) was measured using a pain pressure threshold algometer placed on the extensor carpi radialis of each subject at baseline (BSL) 0 min, 5 min, and 15-mins post EX. Blood lactate (BL) was also measured at these same time points. Change in MPT (Pre vs 0 min Post EX) was quantified using a two-tailed Student’s T-Test. The effect of sex on MPT over time was quantified using a 2 x 2 ANOVA. A Pearson’s correlation was used to evaluate the relationship between MPT vs. BL, respiratory exchange ratio (RER), and VO2 following EX. Data are shown as mean ± SEM. RESULTS: For all subjects, MPT was greater 0 min post-EX (53.3 ± 5.5 N) compared with BSL (31.8 ± 6.1 N) (p < 0.05). Females had a greater increase in MPT (29.6 ± 3 ∆N) relative to males (15.7 ± 8.6 ∆N; p < 0.05). Further, MPT increased in a linear fashion when compared with RER (R = 0.63) and BL (R = 0.76; p < 0.05). MPT remained higher than BSL at 5mins (48 ± 6.3 N) and 15mins (44.4 ± 5.7 N) post-EX relative to BSL. Sex differences in MPT remained at both 5 and 15mins (p < 0.05). The correlation between MPT vs. BL and RER at 5 (BL, r = 0.59; RER, r = 0.47; p < 0.05) and 15 minutes (BL, r = 0.67; RER, r = 0.52; p < 0.05) remained. CONCLUSION: Twenty minutes of vigorous EX induced analgesia for at least 15 minutes following EX. This effect seems to be sensitive to relative EX intensity. These findings may be useful in reducing patient pain levels without the need for pharmaceuticals.

Sympathovagal Balance And Insulin-stimulated Blood Flow Relates To Blood Pressure Dipping In Metabolic Syndrome

Blunted dips in nocturnal systolic blood pressure (SBP) are independently related to cardiovascular disease (CVD). While alterations in blood flow and sympathovagal balance have been suggested to explain dysregulated nocturnal SBP, the role of blood flow and/or sympathovagal balance is unknown in patients with metabolic syndrome (MetS). PURPOSE: We hypothesized that insulin-stimulated blood flow and heart rate recovery (HRR) as well as exaggerated SBP exercise response relates to nocturnal SBP dipping. METHODS: Twenty-eight adults with MetS (ATP III criteria) (53.2 ± 6.5y; 35.8 ± 4.5 kg/m2) were categorized as “dippers” (≥10% change in SBP; 4 M/6F) or “non-dippers” (<10%; 5 M/13F). Twenty-four hour ambulatory blood pressure monitoring was recorded to assess SBP dipping. Participants were fed isocaloric mixed meals for the 24-hr blood pressure monitoring period. A graded, incremental exercise test (VO2peak) was conducted to assess SBP and HR slope response during exercise to estimate sympathetic activity. Rate pressure product (RPP) was also calculated. HRR (peak-post-exercise) at 1 and 2 min post exercise was then used to determine parasympathetic activity. Ultrasound was performed before and after a 2-hr euglycemic hyperinsulinemic clamp (40 mU/m2/min, 90 mg/dl) to assess blood flow. Metabolic panels (e.g. estimated glomerular filtration rate (eGFR), circulating sodium and potassium) were also tested. Three-day food logs were collected in a subgroup (n = 16) to estimate habitual diet. RESULTS: There were no statistical differences in ATP III criteria, age, or eGFR between dippers and non-dippers. Additionally, there were no differences between groups in blood or dietary sodium and potassium. Although HRR and SBP slope during exercise did not differ between dippers and non-dippers, HR slope trended (7.0 ± 1.2 vs. 8.2 ± 1.7, P = 0.09). Interestingly, SBP dipping negatively correlated with HRR 1 minute after exercise (r = -0.60, P = 0.004) as well as insulin stimulated blood flow (r = 0.73, P = 0.04). Also, RPP correlated with nocturnal SBP (r = 0.49, P = 0.02). CONCLUSIONS: HRR, insulin-stimulated blood flow and RPP appear to play a role in nocturnal blood pressure dipping. Together, this work suggests that sympathovagal balance is important for blood flow related CVD risk. Funding: NIH RO1-HL130296.

Acute Exhaustive Exercise under Normoxic and Normobaric Hypoxic Conditions Differentially Regulates Angiogenic Biomarkers in Humans.

Background and Objectives: Angiogenesis describes the outgrowth of new capillaries from already existing ones. Different biomarkers regulate this process. Physical exercise and hypoxia are key stimuli for the activation of different angiogenic molecules, such as the vascular endothelial growth factor (VEGF). matrix metalloproteases (MMPs)-2 and -9 or the extracellular matrix cleavage fragment endostatin. The present study aimed to investigate influences of short-term, intensive cycling exercise under both normoxic and normobaric hypoxic conditions on the mentioned parameters. Materials and Methods: Twelve male subjects (age: 23.3 ± 2.0 years) participated in the study. All subjects conducted four intensive cycling tests until individual exhaustion in a randomized order under the following conditions: normoxia, 2000 m, 3000 m and 4000 m above sea level. Blood samples were taken before (pre) and 10 min, 30 min, 60 min and 240 min post exercise and were analyzed by ELISA. Results: VEGF showed a significantly reduced concentration compared to the pre-value solely under 4000 m at 10 min post exercise. MMP-2 showed significantly reduced concentrations at 240 min post exercise under 4000 m. MMP-9 increased at 240 min post exercise under both 2000 m and 4000 m conditions. Endostatin was significantly increased at 10 min post exercise independently of the applied stimulus. Conclusions: The presented data show that intensive short-term exercise bouts facilitate the bioavailability of angiogenic, ECM (extracellular matrix)-related biomarkers. This finding is interesting for both health- and performance-related research as it demonstrates the positive effects of intensive short exercise interventions.

Neuromuscular Junction Disorders (NMJ) O-NJ001. Electrodiagnostics profile in Myasthenia gravis

Introduction . Repetitive Nerve Stimulation (RNS) has a sensitivity of 50-80% in predicting Myasthenia Gravis (MG). This wide range is affected by type and severity of MG, muscle tested, frequency of stimulation and exercise. There has been a previous study describing these factors but did not confirmed it with the result of Single Fiber (SF) and Acetylcholine Receptor antibody (AChR). Methods . This was a cross-sectional study. Data was from RNS results of MG patients in Electromyography laboratories, Cipto Mangunkusumo National Hospital January to December 2019. Muscle tested on RNS were abductor digiti minimi (ADM) muscle, trapezius (Tr) muscle and orbicularis occuli (OrbOc) muscle. Slow RNS used 3, 5, 7 and 10 Hz stimulation followed by 3 Hz stimulation immediate, 1 minute (min) and 2 min post exercise. Decrease of Compound Muscles Action Potential (CMAP) amplitude > 10% is considered as positive RNS. Results . As much as 47 patients were included in this study. The average age of patients is 43 years old. As much as 44.7% had a positive RNS test, and 70% of the case was positive from OrbOc, followed by Tr (60%) and ADM (30%). Frequency of stimulation that obtained the positivity the most is at 5 Hz, and the 4th wave revealed the lowest point of decreament, followed by the 5th wave. Single Fiber was positive in 57.4% of the case, and AChR was positive in 51.1%. There are 11 patients (23.4%) that has a mismatch results between SF and AChR. Conclusion . RNS without confirmation of SF and AChR may yield a false negative result. Orbicularis Oculi shows the most sensitive muscle tested in RNS, with stimulation of 5 Hz and the 4th waveform the lowest decrement. SF and AChR are still important in confirming strong suspicion patients with MG despite negative results in RNS.

The Effect of Anti-Fatigue of mGluR4, GABA-ARα1 and GABA-BR1 on the Substantia Nigra Pars Reticular During Exercise

Objective: The substantia nigra pars reticular (SNR) is the vital nuclei sending out information from basal ganglia and it plays an important part in motor behavior maintenance and motor regulation. It aims to observe the changes of mGluR4，GABA-ARα1 and GABA-BR1 in substantia nigra pars reticular of rats induced by one single bout of exhaustive exercise, and to discuss the relationship among the expression of mGluR4，GABA-ARα1, GABA-BR1 and exercise fatigue. Methods: Thirty-six male wistar rats were divided into three groups at random including CG, 0EG and 90EG,which having 12 rats. Meanwhile, peripheral blood samples were drawn from the vein of tail at different time points (pre- exercise, exercise for 30 min, exercise for 90 min and exhaustion immediately during exercise, and 30 min and 90 min post exercise) ，and blood concentrations of lactic acid (LD) ，blood urea nitrogen (BUN) and activities of creatine kinase (CK) were detected by automatic analyser. Furthermore, the technique of Immunohistochemistry has been used to indicate the protein expression of metabotropic glutamate receptors like mGluR4 and gamma-aminobutyric acid a receptor like GABAAR1, also gamma-aminobutyric acid B receptor like GABAB1. Results: The expression level of mGluR4 in SNR in immediately post-exercise group (0EG) and 90 min post-exercise group (90EG) increase significantly than control group (CG), and the expression level of GABA-ARα1 in SNR at 0EG and 90EG were also significantly higher than control group, and GABA-BR1 in SNR in 0EG and 90EG were both significantly lower than CG. Moreover, it presented significant increases in the levels of LD, BUN and CK in peripheral blood compared with those at rest. Conclusion: Exercise fatigue could result in up-regulation of mGluR4 expression，GABA-ARα1 and down-regulation of GABA-BR1 expression in substantia nigra pars reticular of rats, and it also induce the muscle injury by increase the level of LD, CK and BUN in peripheral blood, which suggested that substantia nigra pars reticular was an important brain rigion to modulate the motor function, and mGluR4，GABA-ARα1 and GABA-BR1 were three important receptors related with the muscle injury induced by exercise fatigue. So the mGluR4, GABA-ARα1 and GABA-BR1 could be the new novel substance produced to prevent from exercise fatigue.

Load Carriage Exercise Increases Calcium Absorption and Retention in Healthy Young Women

ObjectivesAerobic exercise (EX) reduces circulating ionized Ca (iCa) and increases parathyroid hormone (PTH), but the cause and consequences on Ca handling are unknown. The objective of this study was to determine the effects of EX on Ca kinetics using dual stable Ca isotopes. MethodsTwenty-one healthy women (26.2 ± 6.7 yr; BMI: 22.8 ± 2.1 kg/m2) completed a randomized, crossover study consisting of two 6 day iterations separated by ≥2 wk. One iteration consisted of 3 d of load carriage EX 2 h after breakfast (1 hr treadmill walking at 65% VO2max wearing a vest weighing 30% body wt) on days 0, 2, 4, and the other a no-EX control (CON). Diet was controlled during each iteration, and matched to the volunteer’s usual intake. On day 0, volunteers received one IV bolus of 42Ca, and oral 44Ca with each meal (0600,1200, and 1700). Serial blood draws and 3 urine pools (U1: 0600–1000, U2: 1000–2000, U3: 2000–0800) were collected on day 0; spot urines were collected on days 1–5. Ca isotope ratios were analyzed by Thermal Ionization Mass Spectrometry and total Ca by Siemens Dimension; fractional Ca absorption (FCA) was measured and kinetic modeling determined, rates of Ca deposition (VO+) and resorption (VO–) from bone, and bone Ca balance (Vbal). Circulating PTH and iCa were also measured before, during and after exercise. Data were analyzed by paired T-test or linear mixed models using SPSS. ResultsOn day 0, PTH increased 45 min into EX as compared to pre (+36 pg/ml, P < 0.001) with max increases 15 min post EX (+70.5 pg/ml, P < 0.001). No changes were observed during CON. Compared to pre-EX, iCa decreased at 45 min into EX (-0.14 mmol, P = 0.01) with max 15 min post EX (–0.273 mmol, P < 0.001). Urinary Ca (UCa) was lower during EX in the U1 pool (25 ± 11 mg) vs. CON (38 ± 16 mg, P = 0.001) with no differences in U2 and U3 (P > 0.05). FCA was greater during EX (26.6 ± 8.1%) compared to CON (23.9 ± 8.3%, P < 0.05). Vbal was less negative during EX (–61.3 ± 111 mg) vs. CON (–108 ± 23.5 mg, P < 0.05), but VO+ (574 ± 241 vs. 583 ± 260 mg) and VO– (–636 ± 243 vs. –692 ± 252 mg) were not different (P > 0.05). ConclusionsDuring EX, an increase in FCA and decrease in UCa resulted in a positive shift in Ca balance. The rapid reduction in circulating iCa may be due to a change in the miscible Ca pool, resulting in increased PTH and changes in intestinal and renal Ca handling that support a more positive Ca balance. Funding SourcesDefense Health Program.

Pulsatile load and wasted pressure effort are reduced following an acute bout of aerobic exercise.

Following aerobic exercise, sustained vasodilation and concomitant reductions in total peripheral resistance (TPR) result in a reduction in blood pressure that is maintained for two or more hours. However, the time course for postexercise changes in reflected wave amplitude and other indices of pulsatile load on the left ventricle have not been thoroughly described. Therefore, we tested the hypothesis that reflected wave amplitude is reduced beyond an hour after cycling at 60% V̇o2peak for 60 min. Aortic pressure waveforms were derived in 14 healthy adults (7 men, 7 women; 26 ± 3 yr) from radial pulse waves acquired via high-fidelity applanation tonometry at baseline and every 20 min for 120 min postexercise. Concurrently, left ventricle outflow velocities were acquired via Doppler echocardiography and pressure-flow analyses were performed. Aortic characteristic impedance (Zc), forward (Pf) and backward (Pb) pulse wave amplitude, reflected wave travel time (RWTT), and wasted pressure effort (WPE) were derived. Reductions in aortic blood pressure, Zc, Pf, and Pb were all sustained postexercise whereas increases in RWTT emerged from 60 to 100 min post exercise (all P < 0.05). WPE was reduced by ∼40% from 40 to 100 min post exercise (all P < 0.02). Stepwise multiple regression analysis revealed that the peak ΔWPE was associated with ΔRWTT (β = -0.57, P = 0.003) and ΔPb (β = 0.52, P = 0.006), but not Δcardiac output, ΔTPR, ΔZc, or ΔPf. These results suggest that changes in pulsatile hemodynamics are sustained for ≥100 min following moderate intensity aerobic exercise. Moreover, decreased and delayed reflected pressure waves are associated with decreased left ventricular wasted effort after exercise.NEW & NOTEWORTHY We demonstrate that pulsatile load on the left ventricle is diminished following 60 min of moderate intensity aerobic exercise. During recovery from exercise, the amplitude of the forward and backward traveling pressure waves are attenuated and the arrival of reflected waves is delayed. Thus, the work imposed upon the left ventricle by reflected pressure waves, wasted pressure effort, is decreased after exercise.

The Comparative Methylome and Transcriptome After Change of Direction Compared to Straight Line Running Exercise in Human Skeletal Muscle.

The methylome and transcriptome signatures following exercise that are physiologically and metabolically relevant to sporting contexts such as team sports or health prescription scenarios (e.g., high intensity interval training/HIIT) has not been investigated. To explore this, we performed two different sport/exercise relevant high-intensity running protocols in five male sport team members using a repeated measures design of: (1) change of direction (COD) versus; (2) straight line (ST) running exercise with a wash-out period of at least 2 weeks between trials. Skeletal muscle biopsies collected from the vastus lateralis 30 min and 24 h post exercise, were assayed using 850K methylation arrays and a comparative analysis with recent (subject-unmatched) sprint and acute aerobic exercise meta-analysis transcriptomes was performed. Despite COD and ST exercise being matched for classically defined intensity measures (speed × distance and number of accelerations/decelerations), COD exercise elicited greater movement (GPS-Playerload), physiological (HR), metabolic (lactate) as well as central and peripheral (differential RPE) exertion measures compared with ST exercise, suggesting COD exercise evoked a higher exercise intensity. The exercise response alone across both conditions evoked extensive alterations in the methylome 30 min and 24 h post exercise, particularly in MAPK, AMPK and axon guidance pathways. COD evoked a considerably greater hypomethylated signature across the genome compared with ST exercise, particularly at 30 min post exercise, enriched in: Protein binding, MAPK, AMPK, insulin, and axon guidance pathways. Comparative methylome analysis with sprint running transcriptomes identified considerable overlap, with 49% of genes that were altered at the expression level also differentially methylated after COD exercise. After differential methylated region analysis, we observed that VEGFA and its downstream nuclear transcription factor, NR4A1 had enriched hypomethylation within their promoter regions. VEGFA and NR4A1 were also significantly upregulated in the sprint transcriptome and meta-analysis of exercise transcriptomes. We also confirmed increased gene expression of VEGFA, and considerably larger increases in the expression of canonical metabolic genes PPARGC1A (that encodes PGC1-α) and NR4A3 in COD vs. ST exercise. Overall, we demonstrate that increased physiological/metabolic load via COD exercise in human skeletal muscle evokes considerable epigenetic modifications that are associated with changes in expression of genes responsible for adaptation to exercise.

Effects of aerobic, resistance and concurrent exercise on pulse wave reflection and autonomic modulation in men with elevated blood pressure

The acute effects of exercise modes on pulse wave reflection (PWR) and their relationship with autonomic control remain undefined, particularly in individuals with elevated blood pressure (BP). We compared PWR and autonomic modulation after acute aerobic (AE), resistance (RE), and concurrent exercise (CE) in 15 men with stage-1 hypertension (mean ± SE: 34.7 ± 2.5 years, 28.4 ± 0.6 kg/m2, 133 ± 1/82 ± 2 mmHg). Participants underwent AE, RE, and CE on different days in counterbalanced order. Applanation tonometry and heart rate variability assessments were performed before and 30-min postexercise. Aortic pressure decreased after AE (− 2.4 ± 0.7 mmHg; P = 0.01), RE (− 2.2 ± 0.6 mmHg; P = 0.03), and CE (− 3.1 ± 0.5 mmHg; P = 0.003). Augmentation index remained stable after RE, but lowered after AE (− 5.1 ± 1.7%; P = 0.03) and CE (− 7.6 ± 2.4% P = 0.002). Systolic BP reduction occurred after CE (− 5.3 ± 1.9 mmHg). RR-intervals and parasympathetic modulation lowered after all conditions (~ 30–40%; P < 0.05), while the sympathovagal balance increased after RE (1.2 ± 0.3–1.3 ± 0.3 n.u., P < 0.05). Changes in PWR correlated inversely with sympathetic and directly with vagal modulation in CE. In conclusion, AE, RE, and CE lowered central aortic pressure, but only AE and CE reduced PWR. Overall, those reductions related to decreased parasympathetic and increased sympathetic outflows. Autonomic fluctuations seemed to represent more a consequence than a cause of reduced PWR.

Hypercapnia and hyperlactatemia were positively associated with higher-grade arrhythmias during peak exercise in horses during poor performance evaluation on a high-speed treadmill

Cardiac arrhythmias are common in horses during exercise, especially immediately post-exercise. The objectives of this study were to: (1) describe the frequency and type of cardiac arrhythmias detected in horses during incremental high-speed treadmill exercise testing (ITET); (2) determine if arterial blood gas (ABG) changes at peak and immediately post-exercise were associated with arrhythmias; and (3) determine whether upper or lower airway disease was associated with exercising cardiac arrhythmias. Horses (n = 368) presenting for an ITET underwent resting and exercising upper airway endoscopy, resting, exercising and post-exercise electrocardiography, resting and post-exercise echocardiography and exercising ABG. Arrhythmias were graded by the most severe arrhythmia present. Grade 1 arrhythmias were defined as one or two atrial (APCs) or ventricular premature complexes (VPCs), or one APC and one VPC, detected in 6.9% at peak and 16% at 0-2 min post exercise.. Grade 2 arrhythmias were >2 APCs or VPCs, or both, detected in 5.8% at peak and 16.6% at 0-2 min post exercise. Grade 3 included complex arrhythmias (couplets, triplets, R on T, multiform complexes or paroxysmal atrial or ventricular tachycardia), detected in 4.4% at peak and 7.3% at 0-2 min post exercise.Both partial pressure of arterial CO2 (PaCO2; P = 0.008) and lactate (P = 0.031) were significantly associated with arrhythmias occurring at peak exercise, but not immediately post-exercise. As PaCO2 and lactate increased, arrhythmia severity increased. Blood pH was significantly associated with grades 2 and 3 arrhythmias at 0–2 min post ITET (OR = 0.0002; P < 0.001). There was no significant association between grades 2 and 3 cardiac arrhythmias, inflammatory airway disease (IAD), or exercise-induced pulmonary hemorrhage (EIPH). When adjusted for lactate concentration (P = 0.06), higher PaCO2 concentrations in horses with and without exercising upper respiratory tract (URT) obstruction were associated with higher likelihood of grades 2 and 3 arrhythmias (P < 0.01). This study demonstrated that at peak exercise, with severe hypercapnia and hyperlactatemia, there was increased risk for grades 2 or 3 cardiac arrhythmias and, as the PaCO2 and lactate values increased further, the severity of those arrhythmias increased.