Meta-analysis of the effects of high-intensity intermittent exercise on cardiopulmonary function rehabilitation in patients with stroke

Objective:Systematically evaluate the rehabilitation effect of high-intensity intermittent exercise(HIIT)on cardiovascular function in stroke patients,in order to provide a basis for selecting the best rehabilitation plan for stroke patients.Methods:Computer retrieval of CNKI,WanFang Data,VIP,CBM,Pubmed,EMbase,Web of science,The Cochrane Library databases was conducted from the establishment of the database until March 2023.Randomized controlled trials on HIIT improving cardiovascular function in stroke patients were included,and the included literature was screened,data extracted,and bias risk evaluated.Then,metaanalysis was conducted using RevMan 5.4 software and Stata17.0 software.Results:In the end,9 articles met the research criteria,with a total of 428 patients.The meta-analysis results showed that compared with the control group,HIIT had significant effects on peak oxygen uptake(VO2peak)[MD=3.87,95%CI(3.43,4.31),P<0.00001],minute ventilation(VE)[MD=7.14,95%CI(4.34,9.94),P<0.00001],peak power(WRpeak)[MD=17.13,95%CI(13.7320.54),P<0.00001],6-minute walking distance(6MWD)[MD=43.82,95%CI(16.08,71.56),P=0.002],The intervention effect of the 10 meter walking test(10MWT)[MD=-2.00,95%CI(-2.91,-1.08),P<0.0001]was better than that of the control group.Conclusion:The current analysis results show that compared to conventional rehabilitation therapy or continuous aerobic exercise,HIIT has more advantages in improving the cardiopulmonary function of stroke patients.

Exercise Fatigue Monitoring Based on R-Peak Detection Using UNET-TCN

Moderate exercise contributes to health, but excessive exercise may lead to physicalinjury or even endanger life. It is pressing for a device that can detect the intensity of exercise.Therefore, in order to enable real-time detection of exercise intensity and mitigate the risks of harmfrom excessive exercise, a exercise intensity monitoring system based on the heart rate variability(HRV) from electrocardiogram (ECG) signal and linear features from phonocardiogram (PCG)signal is proposed. The main contributions include: First, accurate analysis of HRV is crucial forsubsequent exercise intensity detection. To enhance HRV analysis, we propose an R-peak detectorbased on encoder-decoder and temporal convolutional network (TCN). Experimental resultsdemonstrate that the proposed R-peak detector achieves an F1 score exceeding 0.99 on real high-intensity exercise ECG datasets. Second, an exercise fatigue monitoring system based on multi-signal feature fusion is proposed. Initially, utilizing the proposed R-peak detector for HRV extractionin exercise intensity detection,which outperforms traditional algorithms, with the system achieving a classification performance of 0.933 sensitivity, 0.802 specificity, and 0.960 accuracy. To further improve the system, we combine HRV with the linear features of PCG. Our exercise intensitydetection system achieves 90.2% specificity, 96.7% recall, and 98.1% accuracy in five-fold cross-validation.

Effect of exercise training intensity on adipose tissue hormone sensitive lipase gene expression in obese women under weight loss

Background:Hormone sensitive lipase(HSL) is an enzyme that regulates adipose tissue lipolysis and plays an important role in chronic exerciseinduced changes in adipose tissue metabolism.The purpose of this study was to determine whether aerobic exercise intensity influences abdominal adipose tissue HSL gene expression in obese women under weight loss. Methods:Thirty women(body mass index(BMI) = 33.0±0.7 kg/m^2,age = 58±1 years) completed one of three 20-week interventions: caloric restriction alone(CR only,n = 8),CR plus moderate-intensity exercise(CR + moderate-intensity,45%—50%heart rate reserve(HRR). 3 day/week,n = 9),or CR plus vigorous-intensity exercise(CR + vigorous-intensity,70%—75%HRR,3 day/week,n = 13).Each group had a similar prescribed energy deficit comprised of underfeeding alone(2800 kcal/week for CR only) or underfeeding(2400 kcal/week) plus exercise(400 kcal/week).Body composition and maximal aerobic capacity(VO_2max) were measured,and subcutaneous abdominal adipose tissue samples were collected before and after the interventions.Adipose tissue HSL gene expression was measured by real time reversetranscriptase polymerase chain reaction. Results:All three interventions reduced body weight,fat mass,percent fat.and waist to a similar degree(all p < 0.01).In addition,all interventions did not change absolute VO_2 max,but increased relative VO_2 max(p < 0.05 to P < 0.01).Compared to pre-intervention.neither CR only nor CR + moderate-intensity changed adipose tissue HSL gene expression,but CR + vigorous-intensity significantly increased adipose tissue HSL gene expression(p < 0.01).The changes of HSL gene expression levels in the CR + vigorous-intensity group were significantly different from those in the CR only(p < 0.05) and CR + moderate-intensity(p < 0.01) groups.In the whole cohort,changes in adipose tissue HSL gene expression correlated positively to changes in absolute(r = 0.55,p < 0.01) and relative(r = 0.32,p = 0.09) VO_2 max. Conclusion:These results support a potential effect of aerobic exercise training intensity on hormone sensitive lipase pathway in adipose tissue metabolism in obese women under weight loss.

Elucidating regulatory processes of intense physical activity by multi-omics analysis

Background:Physiological and biochemical processes across tissues of the body are regulated in response to the high demands of intense physical activity in several occupations,such as firefighting,law enforcement,military,and sports.A better understanding of such processes can ultimately help improve human performance and prevent illnesses in the work environment.Methods:To study regulatory processes in intense physical activity simulating real-life conditions,we performed a multi-omics analysis of 3 biofluids(blood plasma,urine,and saliva)collected from 11 wildland firefighters before and after a 45 min,intense exercise regimen.Omics profiles post-vs.pre-exercise were compared by Student’s t-test followed by pathway analysis and comparison between the different omics modalities.Results:Our multi-omics analysis identified and quantified 3835 proteins,730 lipids and 182 metabolites combining the 3 different types of samples.The blood plasma analysis revealed signatures of tissue damage and acute repair response accompanied by enhanced carbon metabolism to meet energy demands.The urine analysis showed a strong,concomitant regulation of 6 out of 8 identified proteins from the renin-angiotensin system supporting increased excretion of catabolites,reabsorption of nutrients and maintenance of fluid balance.In saliva,we observed a decrease in 3 pro-inflammatory cytokines and an increase in 8 antimicrobial peptides.A systematic literature review identified 6 papers that support an altered susceptibility to respiratory infection.Conclusions:This study shows simultaneous regulatory signatures in biofluids indicative of homeostatic maintenance during intense physical activity with possible effects on increased infection susceptibility,suggesting that caution against respiratory diseases could benefit workers on highly physical demanding jobs.

The influence of different exercise intensities on kicking accuracy and velocity in soccer players

Purpose: The aim of this study was to investigate the influence of different exercise intensities induced by a soccer specific protocol on kicking performance in soccer players.Methods: Twelve semi-professional male soccer players participated in this study and performed maximal instep kicks before and after the implementation of an exercise protocol to determine the influence of different intensities upon kicking ball velocity and the target-hitting accuracy.Results: Analysis of variance designs with repeated measures showed that maximal ball velocity was affected only after the most intense circuit(F(6, 66) = 2.3; p = 0.041; η2= 0.18), while accuracy was not affected in the protocol(F(6, 66) = 0.19; p = 0.98; η2= 0.02). Low and moderate intensities did not affect accuracy or kicking ball velocity.Conclusion: These findings suggest that kicking ball velocity is influenced by high-exercise intensities. Low and moderate exercise intensities do not affect the performance of the kick, and intensity does not influence accuracy. Otherwise, it is possible that other mechanisms(not only physiological) may influence players during the exercise.

Exercise-Induced Bronchoconstriction Diagnostics:Impact of a Repeated Exercise Challenge Test

Exercise-Induced bronchoconstriction (EIB) is related to increased ventilation (VE) during exercise and describes the transient airway narrowing following exercise. A reliable diagnosis is essential for optimal treatment. The impact of a repeated exercise challenge test (ECT) in a clinical setting is not well established and conducting a repeated ECT with the possibility to adjust the exercise intensity on an individual basis may give more information. The aim of the study was to evaluate the test-retest reliability of an ECT for EIB and its association with exercise intensity. Methods: After examination by a pulmonologist, 20 referred subjects with symptoms strong indications of Exercise-Induced bronchoconstriction performed two consecutive exercise challenge tests on a treadmill. The exercise intensity of the repeated test was adjusted. Forced expiratory volume in 1 second (FEV1) was measured before and 1, 3, 6, 10, and 15 minutes after exercise. EIB was defined as a reduction of ≥ 10% in FEV1. Ventilation and heart rate were measured during exercise. Results: Five subjects tested positive in both tests, and ten subjects tested negative in both tests. Three subjects tested positive in the first test only, while two subjects tested positive in the second test only. The exercise intensity was not significantly different between the two tests for any of the subjects. Conclusion: There were 25% divergences in the diagnostic results of two consecutive exercise challenge tests. The difference in the test results was not explained by a difference in the exercise intensity.

Intensity-specific considerations for exercise for patients with inflammatory bowel disease

The rising prevalence of inflammatory bowel disease(IBD)necessitates that patients be given increased access to costeffective interventions to manage the disease.Exercise is a non-pharmacologic intervention that advantageously affects clinical aspects of IBD,including disease activity,immune competency,inflammation,quality of life,fatigue,and psychological factors.It is well established that exercise performed at low-to-moderate intensity across different modalities manifests many of these diseased-related benefits while also ensuring patient safety.Much less is known about higher-intensity exercise.The aim of this review is to summarize findings on the relationship between strenuous exercise and IBD-related outcomes.In healthy adults,prolonged strenuous exercise may unfavorably alter a variety of gastrointestinal(GI)parameters including permeability,blood flow,motility,and neuro-endocrine changes.These intensity-and gut-specific changes are hypothesized to worsen IBD-related clinical presentations such as diarrhea,GI bleeding,and colonic inflammation.Despite this,there also exists the evidence that higher-intensity exercise may positively influence microbiome as well as alter the inflammatory and immunomodulatory changes seen with IBD.Our findings recognize that safety for IBD patients doing prolonged strenuous exercise is no more compromised than those doing lower-intensity work.Safety with prolonged,strenuous exercise may be achieved with adjustments including adequate hydration,nutrition,drug avoidance,and careful attention to patient history and symptomatology.Future work is needed to better understand this intensity-dependent relationship so that guidelines can be created for IBD patients wishing to participate in high-intensity exercise or sport.

Analysis of Regional Differences in Bone Mineral Density Acquisition Factors in Young Women

Purpose: Obtaining high peak bone mass (PBM) and maintaining bone mass is important for the prevention of osteoporosis. This study aimed to examine the regional differences in bone mineral density and factors associated with its acquisition from exercise. Design: The study population included 75 women of 18 - 22 years of age in East Japan and 104 women of 18 - 27 years of age in West Japan. The speed of sound (SOS) of the calcaneus was measured, and the young adult mean (%YAM) was calculated from the SOS. The subjects’ medical history, family history of osteoporosis, and exercise habits were examined using a self-administered questionnaire. Results: There were a significantly greater number of subjects with low %YAM in West Japan. The exercise history and exercise time were significantly higher in West Japan, and the exercise intensity score tended to be higher in East Japan during junior high and high school. A multiple regression analysis by region revealed that the following factors had a significant positive association with the SOS: exercise intensity at elementary school and outdoor sports at junior high school in East Japan;and exercise time at elementary school, muscle mass, and outdoor sports at junior high school in West Japan. On the other hand, exercise time in junior high school in West Japan showed a negative association with the SOS. Conclusions: Regional differences in bone mineral density existed, suggesting a trend toward lower bone mineral density in West Japan. Exercise history and time tended to be higher in West Japan, and exercise intensity scores tended to be higher in East Japan, suggesting that exercise intensity may be more important than exercise time for obtaining bone mineral density.

Cardiac damage in athlete's heart: When the “supernormal” heart fails!

Intense exercise may cause heart remodeling to compensate increases in blood pressure or volume by increasing muscle mass. Cardiac changes do not involve only the left ventricle, but all heart chambers. Physiological cardiac modeling in athletes is associated with normal or enhanced cardiac function, but recent studies have documented decrements in left ventricular function during intense exercise and the release of cardiac markers of necrosis in athlete's blood of uncertain significance. Furthermore, cardiac remodeling may predispose athletes to heart disease and result in electrical remodeling, responsible for arrhythmias. Athlete's heart is a physiological condition and does not require a specific treatment. In some conditions, it is important to differentiate the physiological adaptations from pathological conditions, such as hypertrophic cardiomyopathy, arrhythmogenic dysplasia of the right ventricle, and non-compaction myocardium, for the greater risk of sudden cardiac death of these conditions. Moreover, some drugs and performance-enhancing drugs can cause structural alterations and arrhythmias, therefore, their use should be excluded.

Selection of Suitable Maximum-heart-rate Formulas for Use with Karvonen Formula to Calculate Exercise Intensity

The Karvonen formula, which is widely used to estimate exercise intensity, contains maximum heart rate, H Rmax, as a variable. This study employed pedaling experiments to assess which of the proposed formulas for calculating H Rmaxwas the most suitable for use with the Karvonen formula. First, two kinds of experiments involving an ergometer were performed: an all-in-one-day experiment that tested eight pedaling loads in one day, and a one-load-per-day experiment that tested one load per day for eight days.A comparison of the data on 7 subjects showed that the all-in-one-day type of experiment was better for assessing H Rmaxformulas,at least for the load levels tested in our experiments. A statistical analysis of the experimental data on 47 subjects showed two of the H Rmaxformulas to be suitable for use in the Karvonen formula to estimate exercise intensity for males in their 20 s. In addition, the physical characteristics of a person having the greatest impact on exercise intensity were determined.

Optimal exercise intensity and volume to impact rats with Traditional Chinese Medicine phlegm-dampness constitution

Objective:We aim to investigate the effects of different exercise intensities and volumes on Phlegm-dampness constitution(PDC).Methods:The rats were fed with high-fat food and lived in 75%–85%humidity for 6 weeks to establish the model of PDC.Then PDC rats were screened and intervened by varying exercise intensities for 8 weeks.Weight,constitution scores,blood and liver tissues were collected to detect the concentration of serum total cholesterol(Tch),triglyceride(TG),low-density lipoprotein cholesterol(LDL-C),high-density lipoprotein cholesterol(HDL-C),homocysteine(Hcy),blood glucose(GLU),alanine transaminase(ALT)and percentage of lipid droplet area in liver tissue(PLDA).Results:The weight,Tch,TG,HDL-C,LDL-C,Hcy,GLU,and ALT of rats in moderate-intensity exercise group returned to normal.The rats with high-intensity or low-intensity exercise did not recover as well as moderate-intensity.Conclusion:Different exercise intensities and volumes have different effects on PDC,moderate-intensity exercise over an 8-week intervention is most appropriate.

Effect of yelling on maximal aerobic power during an incremental test of cycling performance

Background：People experiencing strong feelings of fatigue during exercise sometimes subconsciously yell to refocus their efforts and,thus,maintain exercise performance.The present study examined the influenc of yelling during high-intensity exercise by analysing cardiorespiratory reactions and integrated electromyography（i EMG） changes in the vastus lateralis during a cycle ergometer test.Methods：A total of 23 moderately trained people were recruited.The cycling test began with a resistance of 25 W/min,which was gradually increased.During the experimental trial,the participants were required to yell at least 3 times when they felt exhausted;during the controlled trial,they were not allowed to produce any yelling sounds.The testing order was randomly assigned and the 2 trials were completed within an interval between 3–10 days.Two-way repeated measures ANOVA was applied to analyse the differences within and between the trials,and interaction of trial and time.Results：The peak power and time to exhaustion（p〈0.01） in the yelling trial were higher than those in the control trial.However,the vastus lateralis iE MG values of both trials at peak power were not significant y different.During the yelling period at 90%–100% of the maximal effort,a significan time-by-trialinteraction（p〈0.05）wasobservedinoxygenconsumption（VO2）,CO2 production,O2 pulse,ventilation,andrespiratoryrate. Alltheabove measures showed a significan between-trial difference（p〈0.02）.However,heart rate,respiratory exchange ratio,end-tidal oxygen pressure,and ventilatory equivalent for oxygen showed only significan between-trial difference（p〈0.05）,but without interaction of trial and time.Conclusion：Yelling enhances the peak O2 pulse and VO2 and maintains CO2-exclusion efficien y during high-intensity exercise.It may enable maintaining muscle activation without stronger EMG signals being required during high-intensity exercise.

Characteristics of Heart Rate Changes of Elite Sprinters during Speed Training

Objective:To infer the training load from the characteristics of heart rate changes of elite sprinters during maximum intensity training.Methods:Different training loads were determined according to different running distances.Multi-person running in the same group was used to collect the heart rate data of elite sprinters during speed training.Results:the heart rate level was directly related to the exercise load.During the maximum intensity exercise,the heart rate generally increased for about 12 s after the race,which was about 110%of the end-point heart rate.Compared with the low load group(60m),the heart rate of the high load group(100m)continued to rise,but the maximum heart rate level was higher than that of the low load group.The exercise intensity and heart rate change rate of the low load group are greater,the work done by the high load group is more,and the envelope area of the heart rate curve is larger.During intermittent training,under the condition of controlling the interval between groups,the heart rate curve envelope area of the low load group is small,the physical recovery is good,the parameter consistency of each group is good,the heart rate curve envelope area of the high load group is large,and the heart rate response decreases gradually.

Intense exercise can cause excessive apoptosis and synapse plasticity damage in rat hippocampus through Ca2＋ overload and endoplasmic reticulum stress-induced apoptosis pathway

Background Intense exercise can cause injury and apoptosis, but few studies have reported its effect on the central nervous system （CNS）. The initial reason for hippocampus injury is the excitotoxicity of glutamate and calcium overload. Intracellular free Ca2＋ （[Ca2＋]i） overload may trigger the apoptosis pathway and neuron damage. The aim of this study was to investigate whether intense exercise could cause hippocampus apoptosis and neuron damage and then to determine which pathway was activated by this apoptosis. Methods We used one bout of swimming exhaustion rats as models. Intracellular [Ca2~]i was measured to estimate the calcium overload by Fura-2/AM immediately after exhaustion; glial fibrillary acidic protein （GFAP） and synaptophysin （SYP） immunofluorescence were performed for estimating astrocyte activation and synapse plasticity 24 hours after exhaustion. Apoptosis cells were displayed using dUTP nick end labelling （TUNEL） stain; endoplasmic reticulum （ER） stress-induced apoptosis pathway and mitochondrial apoptosis pathway were synchronously detected by Western blotting. Results An increasing level of intracellular [Ca2＋]i （P 〈0.01） was found in the hippocampus immediately after exhaustion. GFAP and SYP immunofluorescence showed that the astrocytes are activated, and the synapse plasticity collapsed significantly 24 hours after exhaustion. TUNEL stain showed that the number of apoptosis cells were notably raised （P 〈0.01）; Western blotting of the apoptosis pathway showed increasing levels of caspase-3 cleavage （P 〈0.01）, Bax （P 〈0.01）, caspase-12 cleavage （P 〈0.01）, C/EBP-homologous protein （CHOP） （P 〈0.01）, and phospho-Junamino- terminal kinases （p-JNK; P 〈0.01） and decreasing level of Bcl-2 （P 〈0.01）. Our results proved that exhaustion can induce hippocampus injury and apoptosis by [Ca2＋]i overload, with collapsed synaptic plasticity as the injury pattern and ER stress-induced apoptosis as the activated pathway. Conclusion Intense exercise can cause excessive apoptosis and synapse plasticity damage in the hippocampus with [Ca2＋]i overload as the initial reason, and thus provides leads for therapeutic interventions in the brain health of athletes.

Activation of γ-aminobutyric Acid （A） Receptor Protects Hippocampus from Intense Exercise-induced Synapses Damage and Apoptosis in Rats

Background： Our previous study has confirmed that one bout of exhaustion （Ex） can cause hippocampus neurocyte damage, excessive apoptosis, and dysfunction, its initial reason is intracellular calcium overload in hippocampus triggered by N-methyl-D-aspartic acid receptor （NMDAR） over-activation. NMDAR activation can be suppressed by y-aminobutyric acid （A） receptor （GABAAR）. Whether GABAAR can prevent intense exercise-induced hippocampus apoptosis, damage, or dysfunction will be studied in this study. Methods： According to dose test, rats were randomly divided into control （Con）, Ex, muscimol （MUS, 0.1 mg/kg） and bicuculline （BIC, 0.5 mg/kg） groups, then all rats underwent once swimming Ex except ones in Con group only underwent training, lntracellular free calcium concentration （[Ca2＋]i） was measured by Fura-2-acetoxymethyl ester; glial fibrillary acidic protein （GFAP） and synaptophysin （SYP） immunofluorescence were also performed; apoptosis were displayed by dUTP nick end labeling （TUNEL） stain; endoplasmic reticulum stress-induced apoptosis pathway was detected by Western blotting analysis; Morris water maze was used to detect learning ability and spatial memory. Results： The appropriate dose was 0.1 mg/kg for MUS and 0.5 mg/kg for BIC. Ex group showed significantly increased [Ca^2＋]i and astrogliosis; TUNEL positive cells and levels of GFAP, B cell lymphoma-2 （Bcl-2） associated X protein （Bax）, caspase-3, caspase-12 cleavage, CCAAT/enhancer binding protein homologous protein （CHOP）, and p-Jun amino-terminal kinase （p-JNK） in Ex group also raised significantly compared to Con group, while SYP, synapse plasticity, and Bcl-2 levels in Ex group were significantly lower than those in Con group. These indexes were back to normal in MUS group. BIC group had the highest levels of [Ca^2＋]i, astrogliosis, TUNEL positive cell, GFAP, Bax, caspase-3, caspase-12 cleavage, CHOP, and p-JNK, it also gained the lowest SYP, synapse plasticity, and Bcl-2 levels among all groups. Water maze test showed that Ex group had longer escape latency （EL） and less quadrant dwell time than Con group; all indexes between MUS and Con groups had no significant differences; BIC had the longest EL and least quadrant dwell time among all groups. Conclusions： Activation of GABAAR could prevent intense exercise-induced synapses damage, excessive apoptosis, and dysfunction of hippocampus.

T10 Test as an Alternative Method to Assess Critical Speed and its Potential Application to Runners

Exercise intensity is usually prescribed based on a metabolic marker,such as maximum oxygen uptake or maximal lactate steady state.Those markers,however,face some difficulties regarding their practical applicability to the general popula-tion.The critical speed emerges as an alternative parameter to determine aerobic exercise intensities through maximal tests using ergometers or field tests,demanding few resources.We evaluated the fidelity of test to predict critical speed and if this parameter could be used to prescribe intensity in aerobic exercise.One hundred recreational runners performed the T10 test and a conventional critical speed test to define running speeds.Out of them,44 runners proceed continuous and interval races.The critical speed assessed from T10 test was then compared to critical speed measured by three maximal runs in the track field(1200 m,2400 m,and 3600 m).We found a strong correlation(r=0.91)and did not find statistical differences(t=1.8,P=0.90)between critical speed assessed by T10(3.89±0.49 m/s)and field-test(3.85±0.51 m/s).T10 is also better associated with running and interval running speeds than metabolic markers.T10 test can be used as a valid alternative method to assess critical speed and to prescribe runs.

Comparison of Cardiovascular Parameters and Internal Training Load of Different 1-h Training Sessions in Non-elite CrossFit^(®)Athletes

Purpose The fact that CrossFit^(®)is the best-known and rapidly growing concept for high-intensity interval training(HIIT)and high-intensity functional training(HIFT)results in a continuous increase of athletes performing CrossFit^(®).In the more than 15,000 CrossFit^(®)Affiliates worldwide,the training concept is usually offered in 1-h training sessions containing the CrossFit^(®)-related workout of the day(WOD),as well as a general warm-up,movement demonstrations,and skill training.Here,we report how physiological parameters measured by heart rate(HR)values vary during four different 1-h CrossFit^(®)training sessions of non-elite athletes(n=27)in a local affiliated training center and what influencing factors may exist.Methods The duration of the 1-h training sessions were divided into a warm-up part(WU-part),a skill development part combined with strength exercises(A-part),followed by the WOD part(B-part).Results Analysis of HR values shows high training intensity(≥91%HR_(max))not throughout the duration of each training session,only during B-part.The mean HR values in B-part differ significantly compared to the remaining training parts(P<0.001)for all four training sessions.Comparison of different CrossFit^(®)experience levels revealed no significant differ-ence in acute physiological demands and training load between beginner and experienced CrossFit^(®)athletes.Conclusion Our results may suggest that practicing CrossFit^(®)in 1-h training sessions combined anaerobic and aerobic exercise intensities,with the training concept allows beginners and experienced athletes to be trained with the same cardio-vascular responses and training intensities.