Subsequent Bout Research Articles

In vivo intracellular Ca2+ profiles after eccentric rat muscle contractions: Addressing the mechanistic bases for repeated bout protection.

Eccentric contractions (ECC) are accompanied by accumulation of intracellular calcium ions ([Ca2+]i) and induce skeletal muscle damage. Suppressed muscle damage in repeated bouts of ECC is well characterized, however, whether it is mediated by altered Ca2+ profiles remains unknown. PURPOSE: We tested the hypothesis that repeated ECC suppresses Ca2+ accumulation via adaptions in Ca2+ regulation. METHODS: Male Wistar rats were divided into two groups: ECC single bout (ECC-SB) and repeated bout (ECC-RB). Tibialis anterior (TA) muscles were subjected to ECC (40 times, 5 sets) once (ECC-SB), or twice 14 days apart (ECC-RB). Under anesthesia, the TA muscle was loaded with Ca2+ indicator Fura-2 AM and the 340/380 nm ratio was evaluated as [Ca2+]i. Ca2+ handling proteins were measured by western blots. RESULTS: ECC induced [Ca2+]i increase in both groups, but ECC-RB evinced a markedly suppressed [Ca2+]i (Time: P < 0.01, Group: P = 0.0357). 5 hours post-ECC, in contrast to the localized [Ca2+]i accumulation in ECC-SB, ECC-RB exhibited lower and more uniform [Ca2+]i (P < 0.01). In ECC-RB mitochondria Ca2+ uniporter complex components, MCU and MICU2, were significantly increased pre-second ECC bout (P < 0.01) and both SERCA1 and MICU1 were better preserved after contractions (P < 0.01). CONCLUSION: 14 days after novel ECC skeletal muscle mitochondrial Ca2+ regulating proteins were elevated. Following subsequent ECC [Ca2+]i accumulation and muscle damage were suppressed and SERCA1 and MICU1 preserved. These findings suggest that tolerance to a subsequent ECC bout is driven, at least in part, by enhanced mitochondrial and SR Ca2+ regulation.

Changes in motor unit behaviour across repeated bouts of eccentric exercise.

Unaccustomed eccentric exercise (EE) is protective against muscle damage following a subsequent bout of similar exercise. One hypothesis suggests the existence of an alteration in motor unit (MU) behaviour during the second bout, which might contribute to the adaptive response. Accordingly, the present study investigated MU changes during repeated bouts of EE. During two bouts of exercise where maximal lengthening dorsiflexion (10 repetitions × 10 sets) was performed 3weeks apart, maximal voluntary isometric torque (MVIC) and MU behaviour (quantified using high-density electromyography; HDsEMG) were measured at baseline, during (after set 5), and post-EE. The HDsEMG signals were decomposed into individual MU discharge timings, and a subset were tracked across each time point. MVIC was reduced similarly in both bouts post-EE (Δ27 vs. 23%, P=0.144), with a comparable amount of total work performed (∼1,300 J; P=0.905). In total, 1,754 MUs were identified and the decline in MVIC was accompanied by a stepwise increase in discharge rate (∼13%; P<0.001). A decrease in relative recruitment was found immediately after EE in Bout 1versus baseline (∼16%; P<0.01), along with reductions in derecruitment thresholds immediately after EE in Bout 2. The coefficient of variation of inter-spike intervals was lower in Bout 2 (∼15%; P<0.001). Our data provide new information regarding a change in MU behaviour during the performance of a repeated bout of EE. Importantly, such changes in MU behaviour might contribute, at least in part, to the repeated bout phenomenon.

Free perforation during the first episode of acute diverticulitis: can it be avoided?

The aims of the present study are to compare the severity of acute diverticulitis in the first episode and in later bouts, and to determine whether there are risk factors for the presence of free perforation at the onset of diverticulitis. A single-center retrospective study was conducted of patients who developed a first episode of acute diverticulitis between January 2011 and August 2021 diagnosed by computed tomography and followed up for at least 1year. Free perforation was considered to be present in patients with diverticulitis stage III and IV according to the Hinchey classification (modified by Wasvary). The analysis included 394 patients (224 men and 170 women) with a mean age of 58years. Forty-eight patients (12.2%) presented free perforation at some point in the course of the disease, 43 during the first episode and 5 during subsequent bouts. The perforation subgroup showed higher rates of stoma creation and mortality (relative risks of 12.3 and 23.5, respectively). In the multivariate analysis, age (OR: 1.041 95% CI 1.016-1.067), lung disease (OR 2.154 95% CI 1.038-4.472) and immunosuppression (OR: 2.812 95% CI 1.315-6.015) were independent factors for free perforation at diverticulitis onset. Free perforation occurs more frequently during the first episode of acute diverticulitis. Older patients, immunosuppressed patients and those with respiratory disease have a greater risk of presenting freely perforated diverticulitis. Therefore, it is essential to maintain a high level of clinical suspicion in these patients to activate early focus control and thus avoid fatal outcomes.

Activation of oxytocinergic neurons enhances torpor in mice.

Mus musculus enters a torpid state in response to caloric restriction in sub-thermoneutral ambient temperatures. This torpid state is characterized by an adaptive and controlled decrease in metabolic rate, heart rate, body temperature, and activity. Previous research has identified the paraventricular nucleus (PVN) within the hypothalamus, a region containing oxytocin neurons, as a location that is active during torpor onset. We hypothesized that oxytocin neurons within the PVN are part of this neural circuit and that activation of oxytocin neurons would deepen and lengthen torpor bouts. We report that activation of oxytocin neurons alone is not sufficient to induce a torpor-like state in the fed mouse, with no significant difference in body temperature or heart rate upon activation of oxytocin neurons. However, we found that activation of oxytocin neurons prior to the onset of daily torpor both deepens and lengthens the subsequent bout, with a 1.7 ± 0.4°C lower body temperature and a 135 ± 32min increase in length. We therefore conclude that oxytocin neurons are involved in the neural circuitry controlling daily torpor in the mouse.

A predictive propensity measure to enter REM sleep.

During sleep periods, most mammals alternate multiple times between rapid-eye-movement (REM) sleep and non-REM (NREM) sleep. A common theory proposes that these transitions are governed by an "hourglass-like" homeostatic need to enter REM sleep that accumulates during the inter-REM interval and partially discharges during REM sleep. However, markers or mechanisms for REM homeostatic pressure remain undetermined. Recently, an analysis of sleep in mice demonstrated that the cumulative distribution function (CDF) of the amount of NREM sleep between REM bouts correlates with REM bout duration, suggesting that time in NREM sleep influences REM sleep need. Here, we build on those results and construct a predictive measure for the propensity to enter REM sleep as a function of time in NREM sleep since the previous REM episode. The REM propensity measure is precisely defined as the probability to enter REM sleep before the accumulation of an additional pre-specified amount of NREM sleep. Analyzing spontaneous sleep in mice, we find that, as NREM sleep accumulates between REM bouts, the REM propensity exhibits a peak value and then decays to zero with further NREM accumulation. We show that the REM propensity at REM onset predicts features of the subsequent REM bout under certain conditions. Specifically, during the light phase and for REM propensities occurring before the peak in propensity, the REM propensity at REM onset is correlated with REM bout duration, and with the probability of the occurrence of a short REM cycle called a sequential REM cycle. Further, we also find that proportionally more REM sleep occurs during sequential REM cycles, supporting a correlation between high values of our REM propensity measure and high REM sleep need. These results support the theory that a homeostatic need to enter REM sleep accrues during NREM sleep, but only for a limited range of NREM sleep accumulation.

Exercise training adaptations in liver glycogen and glycerolipids require hepatic AMP-activated protein kinase in mice.

Regular exercise elicits adaptations in glucose and lipid metabolism that allow the body to meet energy demands of subsequent exercise bouts more effectively and mitigate metabolic diseases including fatty liver. Energy discharged during the acute exercise bouts that comprise exercise training may be a catalyst for liver adaptations. During acute exercise, liver glycogenolysis and gluconeogenesis are accelerated to supply glucose to working muscle. Lower liver energy state imposed by gluconeogenesis and related pathways activates AMP-activated protein kinase (AMPK), which conserves ATP partly by promoting lipid oxidation. This study tested the hypothesis that AMPK is necessary for liver glucose and lipid adaptations to training. Liver-specific AMPKα1α2 knockout (AMPKα1α2fl/fl+AlbCre) mice and littermate controls (AMPKα1α2fl/fl) completed sedentary and exercise training protocols. Liver nutrient fluxes were quantified at rest or during acute exercise following training. Liver metabolites and molecular regulators of metabolism were assessed. Training increased liver glycogen in AMPKα1α2fl/fl mice, but not in AMPKα1α2fl/fl+AlbCre mice. The inability to increase glycogen led to lower glycogenolysis, glucose production, and circulating glucose during acute exercise in trained AMPKα1α2fl/fl+AlbCre mice. Deletion of AMPKα1α2 attenuated training-induced declines in liver diacylglycerides. In particular, training lowered the concentration of unsaturated and elongated fatty acids comprising diacylglycerides in AMPKα1α2fl/fl mice, but not in AMPKα1α2fl/fl+AlbCre mice. Training increased liver triacylglycerides and the desaturation and elongation of fatty acids in triacylglycerides of AMPKα1α2fl/fl+AlbCre mice. These lipid responses were independent of differences in tricarboxylic acid cycle fluxes. In conclusion, AMPK is required for liver training adaptations that are critical to glucose and lipid metabolism.NEW & NOTEWORTHY This study shows that the energy sensor and transducer, AMP-activated protein kinase (AMPK), is necessary for an exercise training-induced: 1) increase in liver glycogen that is necessary for accelerated glycogenolysis during exercise, 2) decrease in liver glycerolipids independent of tricarboxylic acid (TCA) cycle flux, and 3) decline in the desaturation and elongation of fatty acids comprising liver diacylglycerides. The mechanisms defined in these studies have implications for use of regular exercise or AMPK-activators in patients with fatty liver.

Preventive therapy with galcanezumab for two consecutive cluster bouts in patients with episodic cluster headache: an observational multicenter study

BackgroundCluster headache is a severe and disabling primary headache disorder. Galcanezumab is a monoclonal antibody against calcitonin gene-related peptide and a preventive therapy for episodic cluster headache. However, the approval and insurance coverage for episodic cluster headache differ in each country. Additionally, the consistency of efficacy of galcanezumab therapy has not yet been evaluated. This study aimed to assess the efficacy and safety of 240 mg of galcanezumab therapy for consecutive cluster bouts in patients with episodic cluster headache.MethodsThe study enrolled patients with episodic cluster headache who received two courses of galcanezumab therapy at three university hospitals in Republic of Korea between February 2020 and April 2022. The efficacy and safety of galcanezumab were analyzed by comparing daily headache frequency, the number of headache days, and headache intensity and adverse effects during the one-week period before and the third week after galcanezumab injection for each episode of cluster bouts. Paired t-test was used for comparing repeated data from different episodes of cluster bout.ResultsSixteen patients were enrolled in this study. Fourteen patients received galcanezumab therapy for two consecutive cluster bouts. Galcanezumab was administered 24 days and 11 days after the first and second cluster bouts, respectively. The proportion of patients with 50% or more reduction in frequency of daily headache at week 3 from baseline was 86% and 64% during the first and second episodes, respectively. The proportion of patients who received transitional therapy before galcanezumab therapy was higher in the first episode of cluster bout than that in the second episode of cluster bout. No serious adverse reactions or significant differences in adverse effects between cluster bouts were noticed. Two patients received a second galcanezumab therapy during the pre-cluster period, and their cluster periods ended without typical cluster headache attacks 10–60 days after galcanezumab therapy.ConclusionsThis exploratory analysis suggests that galcanezumab may be effective as a preventive therapy in subsequent cluster bouts. Patients with episodic cluster headaches who underwent galcanezumab therapy tended to receive a second round of treatment in the early stages of their next cluster bout without transitional therapy.

Effectiveness of different recovery postures during high-intensity interval training.

High-intensity interval training (HIIT) has become a very popular mode of exercise practiced by the elite as well as recreationally active adults. The aim of this study was to evaluate the effects of four recovery postures that are typically used by exercisers on recovery rate and performance in subsequent bouts of HIIT. Sixteen young, healthy adults performed four HIIT trials with randomized recovery postures. Each trial consisted of four sets of modified Wingate anaerobic power tests (20-sec duration) on a cycle ergometer (Monark 894E, Vansbro, Sweden) separated by four-minute recovery between each exercise set. Participants adopted one of four recovery postures immediately following each set: standing still with hands on the back of the head (head), standing still with hands resting on knees (knees), slow walking with hands on hips (walking), or supine rest (supine). Differences were assessed by a two-way (posture × set) repeated measures analysis of variance. Peak and mean anaerobic power progressively declined within each set (P<0.05), with no differences between postures. Fatigue rate was significantly slower during supine (59±12%) than knees (63±13%). Heart rate recovery was faster (P<0.001) during supine than the other three standing postures. Pulmonary ventilation was not significantly different between postures. Blood lactate concentrations measured after HIIT were not significantly different between postures. Supine posture appears to be more advantageous in facilitating recovery when compared to the three standing postures. None of the recovery postures examined was responsible for better performance in subsequent bouts of HIIT.

Astrocyte Glycogen Is a Major Source of Hypothalamic Lactate in Rats With Recurrent Hypoglycemia.

Astrocytic glycogen serves as the major source of elevated lactate levels in the ventromedial hypothalamus (VMH) of animals exposed to recurring episodes of hypoglycemia. Antecedent hypoglycemia alters VMH glycogen turnover. Antecedent exposure to hypoglycemia enhances glycogen shunt activity in the VMH during subsequent bouts of hypoglycemia. In the immediate hours following a bout of hypoglycemia, sustained elevations in glycogen phosphorylase activity in the VMH of recurrently hypoglycemic animals contribute to sustained elevations in local lactate levels.

Perception of exercise-induced dyspnea after experimentally induced breathing discomfort.

The perception of dyspnea is influenced by both physiological and psychological factors. We sought to determine whether exertional dyspnea perception could be experimentally manipulated through prior exposure to heightened dyspnea while exercising. We hypothesized that dyspnea perception during exercise would be lower following an induced dyspnea task (IDT). Sixteen healthy participants (eight females, eight males) completed two days of exercise testing. Day 1 involved an incremental cycle exercise test starting at 40 W for females and 60 W for males, increasing by 20 W each minute until volitional exhaustion. Following the maximal exercise test on Day 1, participants completed IDT, involving 5 min of exercise at 70% of peak work rate with 500 mL dead space and external resistance (i.e., 6.8 ± 2.3 cm·H2O·s-1·L-1 inspiration, 3.8 ± 0.7 cm·H2O·s-1·L-1 expiration). Day 2 consisted of an incremental exercise test identical to Day 1. At maximal exercise, there were no differences in oxygen uptake (V̇O2; 44.7 ± 7.7vs. 46.5 ± 6.3 mL·kg-1·min-1), minute ventilation (120 ± 35vs. 127 ± 38 L·min-1), dyspnea (6.5 [4, 8.5] vs. 6 [4.25, 8.75]), or leg discomfort (6 [5, 8.75] vs. 7 [5, 9]) between days (all p > 0.05). At 60%-80% of peak V̇O2 (V̇O2peak), dyspnea was significantly lower on Day 2 (-0.75 [-1.375, 0] for 60% and -0.5 [0, -2] for 80%, p < 0.05) despite no differences in relevant physiological variables. The onset of perceived dyspnea occurred at a significantly higher exercise intensity on Day 2 than on Day 1 (42% ± 19%vs. 51% ± 17% V̇O2peak, respectively; p < 0.05). Except for 40% V̇O2peak (p = 0.05), RPE-L was not different at any intensities nor was the onset of perceived leg discomfort different between days (38% ± 14%vs. 43% ± 10% V̇O2peak, respectively; p = 0.10). Exposure to heightened dyspnea alters exercise-induced dyspnea perception during subsequent submaximal exercise bouts.

Exercise induced muscle damage and repeated bout effect: an update for last 10 years and future perspectives

Exercise-induced muscle damage (EIMD) and repeated bout effect (RBE) are widely researched across various populations. EIMD is the muscle damage occurring after one bout of unaccustomed exercise while RBE is the attenuation of the same muscle damage in subsequent second bout. RBE seems to have significant implications for exercise prescription. Despite existence of vast literature, there is lack of clarity on the effects of EIMD and RBE in a healthy population. The purpose of this study is to review the literature on EIMD and RBE in healthy participants published during the last 10 years. The search of major databases (including Scopus, Google Scholar and PubMed) was conducted using specific keywords ‘Exercise induced muscle damage’, ‘Repeated bout effect’, ‘Healthy participants’ ‘Pre-conditioning’, ‘Eccentric exercise’. Studies published from 2011 onwards which included EIMD and RBE assessment in healthy participants were included in this review. Database searching revealed a total of 38 studies on EIMD and RBE in healthy participants. Three major themes of papers were identified that focused on EIMD and RBE along with (1) age related differences, (2) sex-based differences, and (3) response in athletes. Findings of this comprehensive review suggests that both EIMD and RBE are age, and sex specific. Delayed onset muscle soreness played a major role in both EIMD and RBE in all the population types. Female participants are less susceptible to EIMD as compared to age-matched male counterparts. Moreover, both EIMD and RBE are more elicited in middle aged and younger adults as compared to children and older adults while the magnitude of RBE turns out to be minimal in trained individuals due to persisting adaptations.

Functional Data Analysis for Predicting Pediatric Failure to Complete Ten Brief Exercise Bouts.

Physiological response to physical exercise through analysis of cardiopulmonary measurements has been shown to be predictive of a variety of diseases. Nonetheless, the clinical use of exercise testing remains limited because interpretation of test results requires experience and specialized training. Additionally, until this work no methods have identified which dynamic gas exchange or heart rate responses influence an individual's decision to start or stop physical activity. This research examines the use of advanced machine learning methods to predict completion of a test consisting of multiple exercise bouts by a group of healthy children and adolescents. All participants could complete the ten bouts at low or moderate-intensity work rates, however, when the bout work rates were high-intensity, 50% refused to begin the subsequent exercise bout before all ten bouts had been completed (task failure). We explored machine learning strategies to model the relationship between the physiological time series, the participant's anthropometric variables, and the binary outcome variable indicating whether the participant completed the test. The best performing model, a generalized spectral additive model with functional and scalar covariates, achieved 93.6% classification accuracy and an F1 score of 93.5%. Additionally, functional analysis of variance testing showed that participants in the 'failed' and 'success' groups have significantly different functional means in three signals: heart rate, oxygen uptake rate, and carbon dioxide uptake rate. Overall, these results show the capability of functional data analysis with generalized spectral additive models to identify key differences in the exercise-induced responses of participants in multiple bout exercise testing.

Recovery Of Glucose-6-Phosphate But Not ATP Following Fatiguing Skeletal Muscle Contractions In Humans

Intramyocellular ATP depletion can occur during intense muscle contractions if ATP demand exceeds ATP production. If conditions are sufficiently severe, this can lead to a loss of total adenine nucleotides (TAN) in the irreversible step from adenosine monophosphate (AMP) to inosine monophosphate (IMP). The occurrence and bioenergetic implications of ATP depletion during and following intense contractions in vivo are not clear. PURPOSE: To understand the evolution and resolution of changes in vivo in ATP, phosphomonoesters (PME; glucose-6-phosphate (G6P) + IMP), and TAN during fatiguing contractions in humans. METHODS: After providing written informed consent, 9 adults (35 ± 2 yr; 6F) performed 120 maximal isotonic contractions (1 every 2 s) at 20% of peak torque on a non-magnetic knee extension ergometer in a 3 tesla magnetic resonance (MR) system. Phosphorus MR spectra (2-s repetition time) were collected from the vastus lateralis muscle during rest, 4 min of contractions, and 10 min of recovery. Metabolites (ATP; inorganic phosphate, Pi; PME; and phosphocreatine, PCr) were fit using jMRUI and concentrations calculated assuming ATP = 8.2 mM at rest. Standard equations were used to calculate ADP, AMP, IMP and G6P. Statistics: paired t-tests and Pearson correlation. RESULTS: Peak power decreased to 65 ± 17% (mean ± SD) of baseline during contractions (p < 0.01), indicating substantial muscle fatigue. PCr declined rapidly from 32 ± 2 to 7 ± 5 mM (p < 0.01). ATP was maintained during the first 60 s of contractions, then declined steadily to 6.9 ± 0.9 mM (p < 0.01), and was associated with fatigue (r = 0.62 ± 0.3). G6P, ADP, AMP, and IMP increased (p ≤ 0.01, all), and TAN decreased (p < 0.01) throughout the protocol. Intracellular pH fell to 6.72 ± 0.20 (p < 0.01), indicating moderate acidosis. G6P and pH returned to baseline by 10 min recovery, whereas PCr, ATP, IMP and TAN did not (p ≤ 0.01, all). CONCLUSIONS: Intense, dynamic contractions deplete ATP to the point of impaired bioenergetic recovery due to the accumulation of IMP and consequent loss of TAN. In contrast, full recovery of G6P suggests no long-term inhibition of glycolysis under these conditions. The results have important implications for understanding long-duration fatigue and the bioenergetic preparedness of muscle for subsequent bouts of work. Funding: NIH R01-AG058607

Management of Infective Endocarditis in People Who Inject Drugs: A Scientific Statement From the American Heart Association.

The American Heart Association has sponsored both guidelines and scientific statements that address the diagnosis, management, and prevention of infective endocarditis. As a result of the unprecedented and increasing incidence of infective endocarditis cases among people who inject drugs, the American Heart Association sponsored this original scientific statement. It provides a more in-depth focus on the management of infective endocarditis among this unique population than what has been provided in prior American Heart Association infective endocarditis-related documents. A writing group was named and consisted of recognized experts in the fields of infectious diseases, cardiology, addiction medicine, and cardiovascular surgery in October 2021. A literature search was conducted in Embase on November 19, 2021, and multiple terms were used, with 1345 English-language articles identified after removal of duplicates. Management of infective endocarditis in people who inject drugs is complex and requires a unique approach in all aspects of care. Clinicians must appreciate that it requires involvement of a variety of specialists and that consultation by addiction-trained clinicians is as important as that of more traditional members of the endocarditis team to improve infective endocarditis outcomes. Preventive measures are critical in people who inject drugs and are cured of an initial bout of infective endocarditis because they remain at extremely high risk for subsequent bouts of infective endocarditis, regardless of whether injection drug use is continued.

Heart rate and gas exchange dynamic responses to multiple brief exercise bouts (MBEB) in early- and late-pubertal boys and girls.

Natural patterns of physical activity in youth are characterized by brief periods of exercise of varying intensity interspersed with rest. To better understand systemic physiologic response mechanisms in children and adolescents, we examined five responses [heart rate (HR), respiratory rate (RR), oxygen uptake (V̇O2), carbon dioxide production (V̇CO2), and minute ventilation (V̇E), measured breath‐by‐breath] to multiple brief exercise bouts (MBEB). Two groups of healthy participants (early pubertal: 17 female, 20 male; late‐pubertal: 23 female, 21 male) performed five consecutive 2‐min bouts of constant work rate cycle‐ergometer exercise interspersed with 1‐min of rest during separate sessions of low‐ or high‐intensity (~40% or 80% peak work, respectively). For each 2‐min on‐transient and 1‐min off‐transient we calculated the average value of each cardiopulmonary exercise testing (CPET) variable (Y̅). There were significant MBEB changes in 67 of 80 on‐ and off‐transients. Y̅ increased bout‐to‐bout for all CPET variables, and the magnitude of increase was greater in the high‐intensity exercise. We measured the metabolic cost of MBEB, scaled to work performed, for the entire 15 min and found significantly higher V̇O2, V̇CO2, and V̇E costs in the early‐pubertal participants for both low‐ and high‐intensity MBEB. To reduce breath‐by‐breath variability in estimation of CPET variable kinetics, we time‐interpolated (second‐by‐second), superimposed, and averaged responses. Reasonable estimates of τ (<20% coefficient of variation) were found only for on‐transients of HR and V̇O2. There was a remarkable reduction in τHR following the first exercise bout in all groups. Natural patterns of physical activity shape cardiorespiratory responses in healthy children and adolescents. Protocols that measure the effect of a previous bout on the kinetics of subsequent bouts may aid in the clinical utility of CPET.

Tight Margins: Compression Garment Use during Exercise and Recovery—A Systematic Review

Background: Compression garments (CGs) are a popular tool that may act on physiological, physical, neuromuscular, biomechanical, and/or perceptual domains during exercise and recovery from exercise, with varying levels of efficacy. While previous reviews have focused on the effects of CGs during running, high-intensity exercise, and exercise recovery, a comprehensive systematic review that assesses the effectiveness of garment use both during and after exercise has not been recently conducted. Methods: A systematic search of the literature from the earliest record until May 2022 was performed based on the PRISMA-P guidelines for systematic reviews, using the online databases PubMed, SPORTDiscus, and Google Scholar. Results: 160 articles with 2530 total participants were included for analysis in the systematic review, comprised of 103 ‘during exercise’ studies, 42 ‘during recovery’ studies, and 15 combined design studies. Conclusions: During exercise, CGs have a limited effect on global measures of endurance performance but may improve some sport-specific variables (e.g., countermovement jump height). Most muscle proteins/metabolites are unchanged with the use of CGs during exercise, though measures of blood lactate tend to be lowered. CGs for recovery appear to have a positive benefit on subsequent bouts of endurance (e.g., cycling time trials) and resistance exercise (e.g., isokinetic dynamometry). CGs are associated with reductions in lactate dehydrogenase during recovery and are consistently associated with decreases in perceived muscle soreness following fatiguing exercise. This review may provide a useful point of reference for practitioners and researchers interested in the effect of CGs on particular outcome variables or exercise types.

Short-Term Oral Quercetin Supplementation Improves Post-exercise Insulin Sensitivity, Antioxidant Capacity and Enhances Subsequent Cycling Time to Exhaustion in Healthy Adults: A Pilot Study.

AimQuercetin has been reported to have antioxidant and anti-inflammatory properties on health promotion in human studies. The main purpose of this study was to investigate the effect of short-term oral quercetin supplementation on post-exercise whole-body energy metabolism. This study also aimed to determine the effects of supplementation on oxygen stress, inflammation, muscle damage, and high-intensity cycling exercise performance.MethodTwelve healthy participants, physically active students, were recruited to perform a randomized, single-blind crossover study. All subjects completed 7-days of quercetin (quercetin:1,000 mg per day for 7-days) and placebo supplementation in a randomized order. Supplement/placebo was combined with exercise consisting of 70% V̇O2max cycling for 60-min, followed by 3-h of recovery, then a subsequent single bout of cycling exercise with 75% V̇O2max to exhaustion. Time to exhaustion, indicators of muscle damage, as well as blood and gaseous parameters relating to energy metabolism, oxidative stress, inflammatory response, respectively, were determined.ResultsThe results showed that 7-day quercetin supplementation significantly attenuated the post-exercise glucose-induced insulin response, increased total antioxidant capacity (TAC) and superoxidase dismutase (SOD) activities, and mitigated malondialdehyde (MDA) levels during the recovery period (p < 0.05). While subsequent 75% V̇O2max cycling performance was significantly improved after quercetin treatment and accompanied by lower responses of interleukin 6 and creatine kinase at 24-h. However, it’s noted that there were no significant responses in glucose, respiratory exchange rate, tumor necrosis factor-α (TNF-α), myoglobin, and high sensitivity C-reactive protein between quercetin and placebo trials.ConclusionOur findings concluded that 7-day oral quercetin supplementation enhances high-intensity cycling time to exhaustion, which may be due in part to the increase in whole-body insulin-stimulated glucose uptake and attenuation of exercise-induced oxygen stress and pro-inflammation. Therefore, quercetin may be considered an effective ergogenic aid for enhancing high-intensity cycling performance among young adults.

Physiological role of anticipatory cardiorespiratory responses to exercise.

This study aimed to investigate whether anticipatory cardiorespiratory responses vary depending on the intensity of the subsequent exercise bout, and whether anticipatory cardiorespiratory adjustments contribute importantly to enhancing exercise performance during high‐intensity exercise. Eleven healthy men were provided advance notice of the exercise intensity and a countdown to generate anticipation during 10 min prior to exercise at 0, 50, 80 or 95% maximal work‐rate (Experiment 1). A different group of subjects (n = 15) performed a time to exhaustion trial with or without anticipatory countdown (Experiment 2). In Experiment 1, heart rate (HR), oxygen uptake (VO2) and minute ventilation (VE) during pre‐exercise resting period increased over time and depended on the subsequent exercise intensity. Specifically, there was already a 7.4% increase in HR from more than 5 min prior to the start of exercise at 95% maximal work‐rate, followed by progressively augmented increases of 12.5% between 2 and 3 min before exercise, 24.4% between 0 and 1 min before exercise. In Experiment 2, the initial HR for the first 10 s of exercise in the task with anticipation was 11.4% larger compared to without anticipation (p < 0.01), and the difference in HR between the two conditions decreased in a time‐dependent manner. In contrast, the initial increases in VO2 and VE were significantly lower in the task with anticipation than that without anticipation. The time to exhaustion during high‐intensity exercise was 14.6% longer under anticipation condition compared to no anticipation (135 ± 26 s vs. 119 ± 26 s, p = 0.003). In addition, the enhanced exercise performance correlated positively with increased HR response just before and immediately after exercise onset (p < 0.01). These results showed that anticipatory cardiorespiratory adjustments (feedforward control) via the higher brain that operate before starting exercise may play an important role in minimizing the time delay of circulatory response and enhancing performance after onset of high‐intensity exercise in man.

Investigation on the cause of recurrent tuberculosis in a rural area in China using whole-genome sequencing: A retrospective cohort study

Recurrent tuberculosis (TB) in China has been studied in urban areas but not in rural settings. We conducted a retrospective cohort study on all successfully treated bacteriologically confirmed TB patients between 2009 and 2020 in Wusheng County, Sichuan Province using whole-genome sequencing (WGS). Isolates differing by ≤ 12 single nucleotide polymorphisms (SNPs) were considered relapse, otherwise were considered exogenous reinfection, and molecular drug susceptibility results were also compared. In total, 4.9% (75/1532) of successfully treated cases had subsequent bouts of TB, with 4 patients having two subsequent bouts, yielding a total of 79 events and a rate of 8.56 (95% CI 6.86–10.67) cases per 1000 person years, 8.9 times higher than in the general population. Most recurrences (74.4%, 58/79) occurred within three years. The risk for recurrent TB was increased for men and patients with drug-resistant isolates. Among the 44 recurrent events with genotyped paired isolates, 39 were classified as relapse and 5 as exogenous reinfection. Ten (25%, 10/40) recurrent patients acquired new resistance during treatment. Recurrent TB in rural Wusheng was mostly relapse and associated with drug resistance, suggesting the need to improve patient management, resistance testing and patient follow-up for at least 3 years after completing treatment.

Sex-based differences in body core temperature response across repeat work bouts in the heat

ObjectiveTo investigate the effects of repeated work bouts in the heat on peak body core temperature and to explore sex-based differences in body core temperature responses. MethodsFourteen males and fifteen females performed four work bouts (two heavy and two moderate, alternating) in 32.5 °C Wet Bulb Globe Temperature (WBGT), each separated by 30-min seated rest in 28.0 °C WBGT. Participants wore a military combat uniform with body armour and helmet (10 kg load) during the work bouts, removing the vest and helmet during recovery periods. ResultsBody core temperature elevation over time was faster in the first compared with subsequent work bouts of each intensity. Body core temperature elevation was similar between males and females during the first heavy work bout, then remained significantly lower in females for the reminder of the trial. ConclusionsContrary to the assumed progressive elevation in strain, but in agreement with recent literature, a gradual reduction in heat storage in subsequent exercise bouts prevented a cumulative increase in heat strain in the conditions tested.