Submaximal Aerobic Exercise Research Articles

The Concussion, Exercise, and Brain Networks (ConExNet) study: a cohort study aimed at understanding the effects of sub-maximal aerobic exercise on resting state functional brain activity in pediatric concussion

BackgroundRecent scientific evidence has challenged the traditional “rest-is-best” approach for concussion management. It is now thought that “exercise-is-medicine” for concussion, owing to dozens of studies which demonstrate that sub-maximal, graded aerobic exercise can reduce symptom burden and time to symptom resolution. However, the primary neuropathology of concussion is altered functional brain activity. To date, no studies have examined the effects of sub-maximal aerobic exercise on resting state functional brain activity in pediatric concussion. In addition, although exercise is now more widely prescribed following concussion, its cardiopulmonary response is not yet well understood in this population. Our study has two main goals. The first is to understand whether there are exercise-induced resting state functional brain activity differences in children with concussion vs. healthy controls. The second is to profile the physiological response to exercise and understand whether it differs between groups.MethodsWe will perform a single-center, controlled, prospective cohort study of pediatric concussion at a large, urban children’s hospital and academic center. Children with sport-related concussion (aged 12–17 years) will be recruited within 4-weeks of injury by our clinical study team members. Key inclusion criteria include: medical clearance to exercise, no prior concussion or neurological history, and no implants that would preclude MRI. Age- and sex-matched healthy controls will be required to meet the same inclusion criteria and will be recruited through the community. The study will be performed over two visits separated by 24–48 h. Visit 1 involves exercise testing (following the current clinical standard for concussion) and breath-by-breath gas collection using a metabolic cart. Visit 2 involves two functional MRI (fMRI) scans interspersed by 10-minutes of treadmill walking at an intensity calibrated to Visit 1 findings. To address sub-objectives, all participants will be asked to self-report symptoms daily and wear a waist-worn tri-axial accelerometer for 28-days after Visit 2.DiscussionOur study will advance the growing exercise-concussion field by helping us understand whether exercise impacts outcomes beyond symptoms in pediatric concussion. We will also be able to profile the cardiopulmonary response to exercise, which may allow for further understanding (and eventual optimization) of exercise in concussion management.Trial registrationNot applicable.

Short-Term Panax Ginseng Extract Supplementation Reduces Fasting Blood Triacylglycerides and Oxygen Consumption during Sub-Maximal Aerobic Exercise in Male Recreational Athletes.

Ginseng, a popular herbal supplement among athletes, is believed to enhance exercise capacity and performance. This study investigated the short-term effects of Panax ginseng extract (PG) on aerobic capacity, lipid profile, and cytokines. In a 14-day randomized, double-blind trial, male participants took 500 mg of PG daily. Two experiments were conducted: one in 10 km races (n = 31) and another in a laboratory-controlled aerobic capacity test (n = 20). Blood lipid and cytokine profile, ventilation, oxygen consumption, hemodynamic and fatigue parameters, and race time were evaluated. PG supplementation led to reduced total blood lipid levels, particularly in triacylglycerides (10 km races -7.5 mg/dL (95% CI -42 to 28); sub-maximal aerobic test -14.2 mg/dL (95% CI -52 to 23)), while post-exercise blood IL-10 levels were increased (10 km 34.0 pg/mL (95% CI -2.1 to 70.1); sub-maximal aerobic test 4.1 pg/mL (95% CI -2.8 to 11.0)), and oxygen consumption decreased during the sub-maximal aerobic test (VO2: -1.4 mL/min/kg (95% CI -5.8 to -0.6)). No significant differences were noted in race time, hemodynamic, or fatigue parameters. Overall, PG supplementation for 2 weeks showed benefits in blood lipid profile and energy consumption during exercise among recreational athletes. This suggests a potential role for PG in enhancing exercise performance and metabolic health in this population.

Acute and short-term beetroot juice nitrate-rich ingestion enhances cardiovascular responses following aerobic exercise in postmenopausal women with arterial hypertension: A triple-blinded randomized controlled trial

BackgroundThe increase in blood pressure (BP) levels in the postmenopausal period can be partly explained by the decrease in nitric oxide synthases (NOS). ObjectiveTo investigate the acute and one-week effects of beetroot juice nitrate-rich (BRJ-NO3−rich) ingestion on cardiovascular and autonomic performance in response to submaximal aerobic exercise in postmenopausal women with systemic arterial hypertension (SAH) who are physically inactive. MethodsFourteen postmenopausal women with SAH [mean (SD) age: 59(4) y; BMI (kg/m2): 29.2(3.1)] completed submaximal aerobic exercise bouts after an acute and a one-week intervention with BRJ in a placebo-controlled, randomized, triple-blind, crossover design. Participants ingested either BRJ (800 mg of NO3−) or placebo acutely and drank either BRJ (400 mg of NO3−) or placebo every day for the next six days. After two and ½ hours, they performed a session of aerobic submaximal aerobic exercise, and their systolic BP (SBP) and diastolic BP (DBP), flow-mediated dilation (FMD), heart rate (HR) recovery, and HR variability were measured. ResultsIn the post-exercise recovery period, SBP dropped significantly in the BRJ-NO3−rich group (−9.28 mmHg [95%CI: −1.68 to −16.88] ES: −0.65, p = 0.019) compared to placebo after acute ingestion. The FMD values increased after acute BRJ-NO3−rich on post-exercise (3.18 % [0.36 to 5.99] ES: 0.87, p = 0.031). After the one-week intervention, FMD values were higher in the BRJ-NO3−rich group before (4.5 % [1.62 to 7.37] ES: 1.21, p = 0.005) and post-exercise measurements (4.2 % [1.52 to 6.87] ES: 1.22, p = 0.004) vs. placebo. HRV indices with remarkable parasympathetic modulation to heart recovered faster on the BRJ-NO3−rich group than placebo group. No between-group differences were identified in values of HR post-exercise recovery in the 30s, 60s, 120s, 180s, and 300s. ConclusionsAcute and short-term BRJ-NO3−rich ingestion may enhance cardiovascular and autonomic behavior in response to aerobic exercise in postmenopausal women diagnosed with SAH. Clinical trial registry numberhttps://clinicaltrials.gov/ct2/show/NCT05384340.

Exercise-Induced Hypoalgesia in Patients with Chronic Whiplash-Associated Disorders: Differences between Subgroups Based on the Central Sensitization Inventory.

Physical exercise is an important element in the rehabilitation of chronic whiplash-associated disorders, with the physiological process underlying pain reduction called exercise-induced hypoalgesia. In chronic whiplash-associated disorders, exercise-induced hypoalgesia appears impaired, and the research suggests a relationship with symptoms of dysfunctional nociceptive processing, such as central sensitization. This study improves our understanding of exercise-induced hypoalgesia in chronic whiplash-associated disorders by examining the differences between the extent of exercise-induced hypoalgesia in subgroups based on scores on the central sensitization inventory (CSI). Data were collected from 135 participants with chronic whiplash-associated disorders who completed a set of questionnaires. Pain pressure thresholds and temporal summations were assessed before and after a submaximal aerobic bicycle exercise test. We observed no interaction effect between exercise-induced hypoalgesia and the CSI scores for both pain pressure threshold and temporal summation. No overall statistical effect was measured in the analysis of the effect of time. The pain pressure threshold significantly related to the CSI. The temporal summation showed no correlation. During this study, we did not find evidence for a difference in the presence of exercise-induced hypoalgesia when the subgroups were created based on the central sensitization cluster calculator. Limited evidence was found for the influence of CSI scores on the delta pain pressure threshold.

Effect of Acute Caffeine Intake on Fat Oxidation Rate during Fed-State Exercise: A Systematic Review and Meta-Analysis.

Pre-exercise intake of caffeine (from ~3 to 9 mg/kg) has been demonstrated as an effective supplementation strategy to increase fat oxidation during fasted exercise. However, a pre-exercise meal can alter the potential effect of caffeine on fat oxidation during exercise as caffeine modifies postprandial glycaemic and insulinemic responses. Hypothetically, the effect of caffeine on fat oxidation may be reduced or even withdrawn during fed-state exercise. The present systematic review aimed to meta-analyse investigations on the effect of acute caffeine intake on the rate of fat oxidation during submaximal aerobic exercise performed in the fed state (last meal < 5 h before exercise). A total of 18 crossover trials with randomised and placebo-controlled protocols and published between 1982 and 2021 were included, with a total of 228 participants (185 males and 43 females). Data were extracted to compare rates of fat oxidation during exercise with placebo and caffeine at the same exercise intensity, which reported 20 placebo-caffeine pairwise comparisons. A meta-analysis of the studies was performed, using the standardised mean difference (SMD) estimated from Hedges' g, with 95% confidence intervals (CI). In comparison with the placebo, caffeine increased the rate of fat oxidation during fed-state exercise (number of comparisons (n) = 20; p = 0.020, SMD = 0.65, 95% CI = 0.20 to 1.20). Only studies with a dose < 6 mg/kg of caffeine (n = 13) increased the rate of fat oxidation during fed-state exercise (p = 0.004, SMD = 0.86, 95% CI = 0.27 to 1.45), while no such effect was observed in studies with doses ≥6 mg/kg (n = 7; p = 0.97, SMD = -0.03, 95% CI = -1.40 to 1.35). The effect of caffeine on fat oxidation during fed-state exercise was observed in active untrained individuals (n = 13; p < 0.001, SMD = 0.84, 95% CI = 0.39 to 1.30) but not in aerobically trained participants (n = 7; p = 0.27, SMD = 0.50, 95% CI = -0.39 to 1.39). Likewise, the effect of caffeine on fat oxidation was observed in caffeine-naïve participants (n = 9; p < 0.001, SMD = 0.82, 95% CI = 0.45 to 1.19) but not in caffeine consumers (n = 3; p = 0.54, SMD = 0.57, 95% CI = -1.23 to 2.37). In conclusion, acute caffeine intake in combination with a meal ingested within 5 h before the onset of exercise increased the rate of fat oxidation during submaximal aerobic exercise. The magnitude of the effect of caffeine on fat oxidation during fed-state exercise may be modulated by the dose of caffeine administered (higher with <6 mg/kg than with ≥6 mg/kg), participants' aerobic fitness level (higher in active than in aerobically trained individuals), and habituation to caffeine (higher in caffeine-naïve than in caffeine consumers).

Effect of a moderate alcohol dose on physiological responses during rest and prolonged cycling.

We examined the acute effects of a moderate alcohol dose (48g) ingested before prolonged cycling on acute physiological responses in eight healthy males (mean ± SD; 23 ± 2years; 1.77 ± 0.04m; 75.8 ± 4.1kg). In a randomized order, euhydrated participants completed two experimental sessions with the sequence of 150-min seated at rest, 90-min of cycling at 50% of the maximal rate of oxygen consumption ($\dot{\textrm V}\textrm O$2max), 120-min seated at rest. Participants drank 250mL of flavored squash with or without alcohol (vodka; ~16g) at 10, 40, and 70min of the initial resting phase, giving a cumulative fluid intake of 750mL with 48g of alcohol. Heart rate, blood glucose, breath alcohol concentration, and respiratory gasses were recorded throughout the entire trial with cumulative urine volume recorded during both rest phases. Total carbohydrate (control = 115 ± 19g: alcohol = 119 ± 21g; P= 0.303) and lipid (control = 17 ± 4g: alcohol = 20 ± 7g; P= 0.169) oxidation was similar between conditions. Average heart rate was 7% higher in the alcohol condition (control = 111 ± 12bpm; alcohol = 119 ± 11bpm; P= 0.003). Blood glucose concentrations were similar between conditions during (P= 0.782) and after exercise (P= 0.247). Urine output was initially increased between conditions following alcohol ingestion before diminishing (P< 0.001) with no difference in total cumulative urine output (P= 0.331). Consuming an alcoholic drink containing 48g of alcohol in the hour before moderate intensity sub-maximal aerobic exercise led to detectable increases in heart rate and rate of urine production with no effect on substrate use.

Exercise Intolerance After Mild Traumatic Brain Injury Occurs in All Subtypes in the Adult Population.

Thematically grouped symptom clusters are present during the acute timeline of post-mild traumatic brain injuries (mTBI), representing clinical profiles called subtypes. Exercise intolerance has not been evaluated within the subtype classifications and, because guidelines support early submaximal aerobic exercise, further knowledge is required in regard to the exercise capabilities among the concussion subtypes. This cross-sectional study (n = 78) aimed to characterize the presence of exercise intolerance within the clinical subtypes and to explore performance on the Buffalo Concussion Treadmill Test (BCTT) in the adult subacute (2-12 weeks post-injury) mTBI population. All participants were evaluated using the BCTT to determine exercise tolerance. We first used the Neurobehavioral Symptom Inventory (NSI) questionnaire to assign each participant a primary subtype(s). To further explore all five subtypes (headache, cognitive, vestibular, ocular motor, and mood), participants were assessed using a multitude of thematically grouped assessments including self-reported questionnaires, clinical tests of vestibular and ocular motor function, balance function, and computerized cognitive testing. Thirty-seven (47%) subjects were exercise tolerant and 41 (53%) were exercise intolerant. There was no difference in the distribution of primary subtypes between the exercise tolerant and exercise intolerant groups. In addition, no significant differences were found between the exercise tolerant and exercise intolerant groups on other thematically grouped subtype assessments. The exercise intolerant group had a significantly higher resting heart rate (HR), lower percentage of age-predicted maximum HR achieved, lower Borg Rate of Perceived Exertion (RPE), and could walk on the treadmill for less time (lower duration) compared with the exercise tolerant group. The current findings suggest that exercise intolerance is common and pervasive across all five mTBI subtypes. A comprehensive mTBI assessment should include evaluation for exercise intolerance regardless of the primary clustering of symptoms and across patient populations. Therefore, early referral to physical therapists, athletic trainers, or medical clinics that can perform the BCTT may be helpful to initiate appropriate exercise prescriptions for patients with mTBI.

The impact of natural menstrual cycle and oral contraceptive pill phase on substrate oxidation during rest and acute submaximal aerobic exercise.

Previous research has identified sex differences in substrate oxidation during submaximal aerobic exercise including a lower respiratory exchange ratio (RER) in females compared with males. These differences may be related to differences in sex hormones. Our purpose was to examine the impact of the natural menstrual cycle (NAT) and second- and third-generation oral contraceptive pill (OCP2 and OCP3) cycle phases on substrate oxidation during rest and submaximal aerobic exercise. Fifty female participants (18 NAT, 17 OCP2, and 15 OCP3) performed two experimental trials that coincided with the low (i.e., nonactive pill/early follicular) and the high hormone (i.e., active pill/midluteal) phase of their cycle. RER and carbohydrate and lipid oxidation rates were determined from gas exchange measurements performed during 10 min of supine rest, 5 min of seated rest, and two 8-min bouts of submaximal cycling exercise at ∼40% and ∼65% of peak oxygen uptake (V̇o2peak). For all groups, there were no differences in RER between the low and high hormone phases during supine rest (0.73 ± 0.05 vs. 0.74 ± 0.05), seated rest (0.72 ± 0.04 vs. 0.72 ± 0.04), exercise at 40% (0.77 ± 0.04 vs. 0.78 ± 0.04), and 65% V̇o2peak (0.85 ± 0.04 vs. 0.86 ± 0.03; P > 0.19 for all). Similarly, carbohydrate and lipid oxidation rates remained largely unchanged across phases during both rest and exercise, apart from higher carbohydrate oxidation in NAT vs. OCP2 at 40% V̇o2peak (P = 0.019) and 65% V̇o2peak (P = 0.001). NAT and OCPs do not appear to largely influence substrate oxidation at rest and during acute submaximal aerobic exercise.NEW & NOTEWORTHY This study was the first to examine the influence of NAT and two generations of OCPs on substrate oxidation during rest and acute submaximal aerobic exercise. We reported no differences across cycle phases or groups on RER, and minimal impact on carbohydrate or lipid oxidation apart from an increase in carbohydrate oxidation in NAT compared with OCP2 during exercise. Based on these findings, NAT/OCP phase controls may not be necessary in studies investigating substrate oxidation.

The Role of Serotonergic and Noradrenergic Descending Pathways on Performance-Based Cognitive Functioning at Rest and in Response to Exercise in People with Chronic Whiplash-Associated Disorders: A Randomized Controlled Crossover Study.

(1) Background: Dysregulation in serotonergic and noradrenergic systems may be implicated in the neurobiophysiological mechanisms underlying pain-related cognitive impairment in chronic whiplash-associated disorders (CWAD). This study aimed to unravel the role of serotonergic and noradrenergic descending pathways in cognitive functioning at rest and in response to exercise in people with CWAD. (2) Methods: 25 people with CWAD were included in this double-blind, randomized, controlled crossover study. Endogenous descending serotonergic and noradrenergic inhibitory mechanisms were modulated by using a single dose of a selective serotonin reuptake inhibitor (Citalopram) or a selective norepinephrine reuptake inhibitor (Atomoxetine). Cognitive performance was studied at rest and in response to exercise (1) without medication intake; (2) after intake of Citalopram; and (3) after intake of Atomoxetine. (3) Results: After Atomoxetine intake, selective attention improved compared with the no medication day (p < 0.05). In contrast, a single dose of Citalopram had no significant effect on cognitive functioning at rest. When performing pairwise comparisons, improvements in selective attention were found after exercise for the no medication condition (p < 0.05). In contrast, after intake of Citalopram or Atomoxetine, selective and sustained attention worsened after exercise. (4) Conclusions: A single dose of Atomoxetine improved selective attention only in one Stroop condition, and a single dose of Citalopram had no effect on cognitive functioning at rest in people with CWAD. Only without medication intake did selective attention improve in response to exercise, whereas both centrally acting medications worsened cognitive performance in response to a submaximal aerobic exercise bout in people with CWAD.

Nitrate-rich beet juice intake on cardiovascular performance in response to exercise in postmenopausal women with arterial hypertension: study protocol for a randomized controlled trial

BackgroundThere is no evidence of the use of beetroot juice with a previously recommended dose of nitrate (NO3) (> 300 mg) on the cardiovascular performance during and recovery following exercise in postmenopausal women with systemic arterial hypertension (SAH).MethodsWe will investigate the effects of beetroot juice rich in NO3 acutely (800 mg) and during a week with daily doses (400 mg) on blood pressure, heart rate (HR), cardiac autonomic control, endothelial function, inflammatory, hormonal, and stress biomarkers oxidative stress and enzymes involved in nitric oxide synthesis and mitochondrial regulation, under resting conditions, as well as mediated by submaximal aerobic exercise sessions. Through a randomized, crossover, triple-blind, placebo-controlled clinical trial, 25 physically inactive women with SAH will undergo an acute and 1-week trial, each with two intervention protocols: (1) placebo and (2) beetroot, in which will ingest beet juice with or without NO3 in its composition with a 7-day washout interval. On collection days, exercise will be performed on a treadmill for 40 min at a speed corresponding to 65–70% of VO2peak. The collection of variables (cardiovascular, autonomic, and blood samples for molecular analyses) of the study will take place at rest (135 min after ingestion of the intervention), during exercise (40 min), and in the effort recovery stage (during 60 min) based on previously validated protocols. The collections were arranged so that the measurement of one variable does not interfere with the other and that they have adequate intervals between them.DiscussionThe results of this research may help in the real understanding of the nutritional compounds capable of generating safety to the cardiovascular system during physical exercise, especially for women who are aging and who have cardiovascular limitations (e.g., arterial hypertension) to perform physical exercise. Therefore, our results will be able to help specific nutritional recommendations to optimize cardiovascular health.Trial registrationClinicalTrials.gov NCT05384340. Registered on May 20, 2022.

Effect of Exercise on ECG Components and their Correlation with Body Mass Index among Young Asymptomatic Obese and Non-obese Individuals: A Cross-sectional Study

Introduction: The worldwide higher prevalence of obesity is currently one of the most important reasons for the occurrence of several health disorders, along with an increased risk of mortality and morbidity. However, the magnitude of the effect of sub-maximal aerobic exercise on cardiac autonomic and electrical function among Indian obese individuals has yet to be established. Aim: To evaluate the effect of exercise on ECG components and their correlation with Body Mass Index (BMI) among young asymptomatic obese and non-obese individuals, in order to assess the risk for developing Cardiovascular Diseases (CVD) in the future. Materials and Methods: An observational cross-sectional study was conducted at the Autonomic Research Laboratory of the Physiology Department at RG Kar Medical College and Hospital, Kolkata, between January 2017 to December 2017. Two hundred healthy medicos were divided into two groups: Obese (BMI ≥25 kg/m²; n=88) and non-obese (BMI ≥18.5 to ≤23 kg/m²; n=112). Resting Blood Pressure (BP) was manually recorded, followed by the recording of long lead-II ECG in the supine posture both at rest and ten minutes after submaximal (50% VO2 max) aerobic exercise on a treadmill using the modified Bruce protocol and following the Astrand-Rhyming nomogram. The HR, QT interval, and RR interval were recorded from the lead-II ECG. The measured QT interval was corrected using Bazett’s formula (QTC=QT/√RR). The results were analysed using both unpaired and paired t-tests and the Pearson correlation coefficient in Graphpad-Quickcalc software. Results: Significant prolongation of the QTc interval both at rest (p-value: 0.019) and after exercise (p-value: 0.044), along with delayed Heart Rate Recovery (HRR) (p-value: 0.001), were observed among the obese compared to the non-obese population. Additionally, a significantly positive linear correlation was observed between BMI and ECG components at rest (BMIRHR: r:+0.293; p: 0.005 and BMI-QTc Interval: r:+0.226; p-value: 0.034) and during the recovery state (BMI-HRR: r:+0.42; p-value: 0.00004 and BMI-QTc Interval: r:+0.365; p-value: 0.0004), only among the obese. Conclusion: At rest, obese individuals had an elevated QTc, which could be due to alterations in cardiac autonomic function, along with a significant positive correlation between BMI and RHR, indicating lower aerobic fitness in this population. Prolongation of the QTc interval, delayed decrease in HR, and a significant positive correlation with BMI after exercise in obese individuals indicated myocardial repolarisation instability, autonomic dysfunction, and an increased risk of out-of-hospital sudden cardiac events in these individuals.

Effect of 3 and 6 mg/kg of caffeine on fat oxidation during exercise in healthy active females.

The aim of this study was to investigate the effect of 3 and 6 mg of caffeine per kg of body mass (mg/kg) on whole-body substrate oxidation during an incremental cycling exercise test in healthy active women. Using a double-blind placebo-controlled counterbalanced experimental design, 14 subjects performed three identical exercise trials after the ingestion of 3 or 6 mg/kg of caffeine or placebo. The exercise trials consisted of an incremental test on a cycle ergometer with 3-min stages at workloads from 30 to 70% of maximal oxygen uptake (VO2max). Substrate oxidation rates were measured by indirect calorimetry. During exercise, there was a significant effect of substance (F = 5.221; p = 0.016) on fat oxidation rate. In comparison to the placebo, 3 mg/kg of caffeine increased fat oxidation rates at 30 to 60% of VO2max (all p < 0.050) and 6 mg/kg at 30 to 50% of VO2max (all p < 0.050). There was also a significant effect of substance (F = 5.221; p = 0.016) on carbohydrate oxidation rate (F = 9.632; p < 0.001). In comparison to placebo, both caffeine doses decreased carbohydrate oxidation rates at 40 to 60% VO2max (all p < 0.050). The maximal rate of fat oxidation with placebo was 0.24 ± 0.03 g/min, which increased with 3 mg/kg to 0.29 ± 0.04 g/min (p = 0.032) and to 0.29 ± 0.03 with 6 mg/kg of caffeine (p = 0.042). Acute intake of caffeine improves the utilization of fat as a fuel during submaximal aerobic exercise in healthy active women with an effect of similar magnitude after the intake of 3 and 6 mg of caffeine per kg of body mass. Thus, the use of 3 mg/kg of caffeine would be more recommended than 6 mg/kg for women seeking increased fat utilization during submaximal exercise.

The Influence of Family History of Type 2 Diabetes on Metabolism during Submaximal Aerobic Exercise and in the Recovery Period in Postmenopausal Women.

Aging and family history of type 2 diabetes (T2D) are known risk factors of T2D. Younger first-degree relatives (FDR) of T2D patients have shown early metabolic alterations, which could limit exercise's ability to prevent T2D. Thus, the objective was to determine whether exercise metabolism was altered during submaximal exercise in FDR postmenopausal women. Nineteen inactive postmenopausal women (control: 10, FDR: 9) aged 60 to 75 years old underwent an incremental test on a cycle ergometer with intensity ranging from 40 to 70% of peak power output. Participants consumed 50 mg of 13C-palmitate 2 h before the test. At the end of each stage, glucose, lactate, glycerol, non-esterified fatty acids and 13C-palmitate were measured in plasma, and 13CO2 was measured in breath samples. Gas exchanges and heart rate were both monitored continuously. There were no between-group differences in substrate oxidation, plasma substrate concentrations or 13C recovered in plasma or breath. Interestingly, despite exercising at a similar relative intensity to control, FDR were consistently at a lower percentage of heart rate reserve. Overall, substrate plasma concentration and oxidation are not affected by family history of T2D in postmenopausal women and therefore not a participating mechanism in the altered response to exercise previously reported. More studies are required to better understand the mechanisms involved in this response.

Effect of caffeine intake on fat oxidation rate during exercise: is there a dose-response effect?

The effect of caffeine to enhance fat utilisation as fuel for submaximal aerobic exercise is well established. However, it is unknown whether this effect is dose dependent. The aim of this study was to investigate the effect of 3 and 6mg of caffeine per kg of body mass (mg/kg) on whole-body substrate oxidation during an incremental cycling exercise test. In a double-blind, randomised, and counterbalanced experiment, 18 recreationally active males (maximal oxygen uptake [VO2max] = 56.7 ± 8.2mL/kg/min) performed three experimental trials after ingesting either 3mg/kg of caffeine, 6mg/kg of caffeine or a placebo (cellulose). The trials consisted of an incremental exercise test on a cycle ergometer with 3-min stages at workloads from 30 to 80% of VO2max. Energy expenditure, fat oxidation rate, and carbohydrate oxidation rate were continuously measured by indirect calorimetry. During exercise, there was significant effect of substance (F = 7.969; P = 0.004) on fat oxidation rate. In comparison to the placebo, the rate of fat oxidation was higher with 3mg/kg of caffeine at 30, 40, 50 and 70% of VO2max [all P < 0.050, effect sizes (ES) from 0.38 to 0.50] and with 6mg/kg of caffeine at 30, 40, 50, 60 and 70% of VO2max (all P < 0.050, ES from 0.28 to 0.76). Both 3mg/kg (0.40 ± 0.21g/min, P = 0.021, ES = 0.57) and 6mg/kg of caffeine (0.40 ± 0.17g/min P = 0.001, ES = 0.60) increased the maximal rate of fat oxidation during exercise over the placebo (0.31 ± 0.15g/min). None of the caffeine doses produced any significant effect on energy expenditure or heart rate during exercise, while both caffeine doses reduced perceived fatigue at 80% of VO2max (all P < 0.050, ES from 0.71 to 1.48). The effect of caffeine to enhance fat oxidation during submaximal aerobic exercise is of similar magnitude with 3 and 6mg of caffeine per kg of body mass. Thus, a dose of 3mg of caffeine per kg of body mass would be sufficient to enhance fat utilisation as fuel during submaximal exercise.

Exercise-induced hypoalgesic effects of different types of physical exercise in individuals with neck pain: A systematic review and meta-analysis.

To evaluate the exercise-induced hypoalgesic (EIH) effects of different types of physical exercise in individuals with neck pain. Systematic review with meta-analysis. An electronic search of six databases was completed to include studies assessing EIH effects on neck pain. Randomized controlled trials, controlled trials, and observational studies that assessed before and immediate after-effects of a single session of physical exercise in people with neck pain were included. Two reviewers independently screened records, extracted outcomes, assessed the risk of bias, and rated the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. EIH is characterized by increased pain threshold, pain tolerance, and/or decreased sensitivity to painful stimuli or unpleasantness, which may last up to 30 min after a single bout of exercise. EIH is usually measured with quantitative sensory testing (QST) and is mostly taken as the difference between pre- and postexercise pressure pain threshold (PPT). Data were pooled and analyzed using a fixed-effect meta-analysis. Eleven articles were included in this review; nine with low risk of bias and two with some concerns about the risk of bias. Three studies with chronic whiplash-associated disorders (WAD) were included in the meta-analysis; isometric exercise had a larger EIH effect at the local testing site compared with submaximal aerobic exercises (MD=-0.21, [95% CI=-0.43, 0.00], p=0.05, I2 = 92%), submaximal aerobic and isometric exercises had equal EIH effects at the remote testing site (MD=0.01, [95% CI=-0.33, 0.35], p=0.95, I2 = 0%), and submaximal aerobic exercises exerted comparably larger EIH effect at the remote testing site than local testing site (MD=-0.01, [95% CI=-0.20, 0.18], p=0.93, I2 = 56%). The certainty of evidence (GRADE) for these analyses was low to very low. According to the descriptive analysis of the studies of chronic nonspecific neck pain, isometric and range of motion (ROM) exercises have shown EIH effects. Active stretching exercises have illustrated contradictory effects. Isometric and ROM exercises exerted hypoalgesia at local and remote sites. A larger EIH effect following submaximal aerobic exercises was exerted at the remote testing site compared with the local site.

The effect of aerobic exercises of different intensities on anxiety, cigarette addiction, sleep quality, and quality of life in former smokers.

There is a worldwide struggle to quit smoking and prevent relapsing. Aerobic exercises are frequently utilized to aid in smoking cessation and prevent relapse. This study aimed to investigate the effects of aerobic exercises of different intensity on the level of anxiety, smoking addiction, and quality of sleep and life in former smokers. The study included 60 people aged 18 to 45 who had quit smoking within the previous month. Individuals were randomly assigned to control (CON), mild-intensity aerobic activity (MIA), and moderate-intensity aerobic activity (MoIA) groups. The MIA group did submaximal aerobic exercises at 40% of maximum heart rate (MHR), while the MoIA group did them at 60% of MHR for 8weeks/3days. Participants' anxiety levels were assessed using the Beck Anxiety Scale (BAS), smoking addiction was assessed using the Fagerström Test for Nicotine Dependence and Substance Craving Scale (SCS), sleep quality was assessed using the Pittsburgh Sleep Quality Index, and quality of life was assessed using the SF-36 Short Form Scale (SF-36). The SCS score of the MoIA group declined more than the MIA and CON groups, and the MIA group had a lower sleep disturbance score than other groups when the influence of exercise training was assessed over time (p < 0.05). Aerobic exercise had no influence on SF-36 or BAS scores (p > 0.05). The benefits of mild and moderate aerobic exercise on quality of life and anxiety are similar. However, mild-intensity aerobic exercises may be suitable for sleep difficulties while moderate-intensity aerobic exercises may be preferred for reducing smoking addiction.

Bitter Orange (Citrus aurantium L.) Intake Before Submaximal Aerobic Exercise Is Safe for Cardiovascular and Autonomic Systems in Healthy Males: A Randomized Trial.

BackgroundThere are still no studies of the cardiovascular safety of the isolated use of Citrus aurantium in aerobic submaximal exercise.ObjectiveTo evaluate the effect of C. aurantium supplementation on the recovery of cardiorespiratory and autonomic parameters following a session of submaximal aerobic exercise.MethodsTwelve healthy male adults achieved a crossover, randomized, double-blind, and placebo-controlled trial. C. aurantium (600 mg, p-synephrine at 30% amount [180 mg]) or placebo (600 mg of starch) were ingested 90 min before evaluation in randomized days. We evaluated systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), mean arterial pressure (MAP), heart rate (HR) and, HR variability indexes at Rest and during 60 min of recovery from exercise.ResultsCitrus aurantium ingestion accelerated the reduction in SBP after exercise, anticipated the return of vagal modulation of the heart after exercise via the HF (ms2), pNN50 (%), and 2 UV% indices. Moreover, rushed the output of sympathetic modulation after exercise via the 0V% index. No unfavorable cardiovascular effects were achieved for HR, DBP, PP, and MAP parameters.ConclusionsCitrus aurantium was shown to be safe for the cardiovascular and autonomic systems alongside submaximal aerobic exercise in healthy males.

Comparison of intermittent pneumatic compression and active recovery after sub-maximal aerobic exercise in collegiate soccer players: in relation with heart rate variability and heart rate recovery

Comparison of intermittent pneumatic compression and active recovery after sub-maximal aerobic exercise in collegiate soccer players: in relation with heart rate variability and heart rate recovery

Abstract WP62: Safety Of Submaximal Aerobic Exercise Testing For People With Subacute Stroke And Comorbidity: A Scoping Review

Introduction: Despite aerobic exercise (AE) testing being a key recommendation for stroke rehabilitation, less than half of physical therapists working with individuals post-stroke perform this practice. Concern for adverse cardiovascular events and inadequate guidance on how to conduct AE testing for individuals with stroke and comorbidity are key barriers. This review aims to describe submaximal AE testing protocols with evidence of safety, defined as less than 11% occurrence of serious adverse events, for people with subacute stroke and comorbidity. Methods: MEDLINE, EMBASE, PsycINFO, CINAHL and SPORTDiscus were searched from inception to October 29, 2020. Published studies that involved submaximal AE testing with individuals with subacute stroke and reported on adverse events during testing were included. Two reviewers independently conducted title and abstract, and full-text screening. One reviewer conducted data extraction, verified by a second reviewer. Results: Sixteen studies involving 595 participants were included. Hypertension (35%), cardiovascular disease (14%) and atrial fibrillation (8%) were the most common cardiovascular comorbidities, while, diabetes (25%), dyslipidemia (23%) and smoking history (11%) were the most common general comorbidities affecting participants with stroke. Evidence of safety for individuals with stroke and comorbidity was found for incremental bicycle (n=5), recumbent stepper (n=3), body weight support treadmill (n=1) and upper extremity ergometer (n=1) protocols; constant load bicycle (n=1) and body weight support treadmill (n=1) protocols; and field (n=10) protocols. Heart rate (95%), blood pressure (82%) and oxygen consumption (72%) monitoring were most frequently done. Test termination criteria based on volition/fatigue (59%) and heart rate (55%) were most commonly reported. Conclusion: A range of submaximal AE testing protocols utilizing diverse exercise modalities can be safely conducted on people with subacute stroke and comorbid conditions that are perceived to increase the risk for serious adverse events. These protocols can be used to guide the development of more specific clinical practice guidelines for conducting AE testing on individuals with stroke and comorbidity.

Impact of an Acute Bout of Submaximal Aerobic Exercise on Circulating Leukocytes in Individuals with Spinal Cord Injury

Impact of an Acute Bout of Submaximal Aerobic Exercise on Circulating Leukocytes in Individuals with Spinal Cord Injury