Effectiveness of high intensity interval training on cardiorespiratory fitness and endothelial function in type 2 diabetes:A systematic review

BACKGROUND Type 2 diabetes mellitus(T2DM)is a chronic metabolic syndrome characterized by insulin resistance and hyperglycemia that may lead to endothelial dysfunction,reduced functional capacity and exercise intolerance.Regular aerobic exercise has been promoted as the most beneficial non-pharmacological treatment of cardiovascular diseases.High intensity interval training(HIIT)seems to be superior than moderate-intensity continuous training(MICT)in cardiovascular diseases by improving brachial artery flow-mediated dilation(FMD)and cardiorespiratory fitness to a greater extent.However,the beneficial effects of HIIT in patients with T2DM still remain under investigation and number of studies is limited.AIM To evaluate the effectiveness of high intensity interval training on cardiorespiratory fitness and endothelial function in patients with T2DM.METHODS We performed a search on PubMed,PEDro and CINAHL databases,selecting papers published between December 2012 and December 2022 and identified published randomized controlled trials(RCTs)in the English language that included community or outpatient exercise training programs in patients with T2DM.RCTs were assessed for methodological rigor and risk of bias via the Physiotherapy Evidence Database(PEDro).The primary outcome was peak VO_(2 ) and the secondary outcome was endothelial function assessed either by FMD or other indices of microcirculation.RESULTS Twelve studies were included in our systematic review.The 12 RCTs resulted in 661 participants in total.HIIT was performed in 310 patients(46.8%),MICT to 271 and the rest 80 belonged to the control group.Peak VO_(2 ) increased in 10 out of 12 studies after HIIT.Ten studies compared HIIT with other exercise regimens(MICT or strength endurance)and 4 of them demonstrated additional beneficial effects of HIIT over MICT or other exercise regimens.Moreover,4 studies explored the effects of HIIT on endothelial function and FMD in T2DM patients.In 2 of them,HIIT further improved endothelial function compared to MICT and/or the control group while in the rest 2 studies no differences between HIIT and MICT were observed.CONCLUSION Regular aerobic exercise training has beneficial effects on cardiorespiratory fitness and endothelial function in T2DM patients.HIIT may be superior by improving these parameters to a greater extent than MICT.

Effects of High-Intensity Intermittent Training on Metabolic Parameters and Irisin Levels in High-Fat-Fed Rats

Objective:To investigate the effects of high-intensity intermittent training(HIIT)on preventing significant weight gain and provide scientific theoretical support and practical guidance for reducing the occurrence of obesity.Methods:Twenty-four Sprague-Dawley rats were randomly divided into four groups:the control sedentary group(CS),the high-fat sedentary group(HS),the high-fat continuous exercise group(HE),and the high-fat intermittent exercise group(HI).The HE and HI groups underwent five days of continuous low-intensity exercise and eight weeks of high-intensity intermittent exercise.Weekly monitoring included measurements of food intake and body weight.An automatic biochemical analyzer was used to assess blood lipid and glucose levels,while ELISA kits measured serum insulin and irisin content.H&E staining was used to observe adipocyte size.Results:In the HS group,body weight,blood lipid levels,blood glucose levels,and adipocyte size significantly increased,while the QUICKI index decreased.In the HI group,body weight,blood lipid levels,blood glucose levels,and adipocyte size decreased,and the QUICKI index increased.The effects of high-intensity intermittent exercise were superior to those of continuous low-intensity exercise.In the HI group,serum irisin levels did not change significantly after exercise,while in the HE group,there was a slight upward trend in irisin levels.Conclusion:A high-fat diet induced abnormal metabolism in rats.HIIT effectively prevents metabolic abnormalities induced by a high-fat diet,and its effects are more pronounced than those of low-intensity exercise.HIIT stimulates the secretion of blood irisin,affecting secretion levels,and may represent a novel mechanism for maintaining metabolic homeostasis.This has important implications for controlling significant weight gain.

Femoral neck stress fracture and medial tibial stress syndrome following high intensity interval training: A case report and review of literature

BACKGROUND Femoral and tibial stress injuries are commonly found in long distance running athletes.Stress fractures have rarely been reported in athletes performing high intensity interval training(HIIT)exercise.The objective of this study was to report a case of a patient who presented with medial tibial stress syndrome and femoral neck stress fracture after performing HIIT exercises.CASE SUMMARY A 26 year old female presented with bilateral medial tibial pain.She had been performing HIIT exercise for 45 min,five times weekly,for a seven month period.Her tibial pain was gradual in onset,and was now severe and worse on exercise,despite six weeks of rest.Magnetic resonance imaging(MRI)revealed bilateral medial tibial stress syndrome.As she was taking norethisterone for birth control,a dual energy X-ray absorbitometry scan was performed which demonstrated normal bone mineral density of her lumbar spine and femoral neck.She was managed conservatively with analgesia and physiotherapy,but continued to exercise against medical advice.She presented again six months later with severe right hip pain.MRI of her right hip demonstrated an incomplete stress fracture of her subtrochanteric region.Her symptoms resolved with strict rest and physiotherapy.CONCLUSION HIIT may cause stress injury of the tibia and femur in young individuals.

The Comparison of the Effects of Two Types of High Intensity Interval Training （HILT） on Body Mass and Physiological Indexes in Inactive Female Students

The aim of this study was to compare the effects of two types of high intensity interval training （HIIT） on body mass and physiological indexes in inactive female students. 27 inactive female students （mean age 24.81 ±0.66 yr, height 162.09 ±0.67 cm, weight 59.41 ±0.33 kg） were voluntarily selected and randomly assigned to three groups （each group = 9 subjects） of high intensity interval training （type I）, high intensity interval training （type 2） and control. HIIT （type 1） （8 seconds of sprint running and 12 seconds of active recovery） was performed for 4 weeks, 3 sessions per week, 6-9 min. per session with above 90% maxHR. HIlT （type 2） （40-m shuttle run test with maximum speed） was performed with above 90% max HR while the control group did not participate in any training. Data analysis with dependent t test showed that HIIT （type 1） and HIlT （type 2） significantly increased VO2max while they decreased fat percentage and BMI. The intergroup data were analyzed by one-way ANOVA at P 〈 0.05. The results showed a significant difference among HIlT （type 1）, HIIT （type 2） and control groups in VO2max, BMI and fat percentage.

Suppressive effects of exercise-conditioned serum on cancer cells:A narrative review of the influence of exercise mode,volume,and intensity

Cancer is a major cause of morbidity and mortality worldwide,and the incidence is increasing,highlighting the need for effective strategies to treat this disease.Exercise has emerged as fundamental therapeutic medicine in the management of cancer,associated with a lower risk of recur-rence and increased survival.Several avenues of research demonstrate reduction in growth,proliferation,and increased apoptosis of cancer cells,including breast,prostate,colorectal,and lung cancer,when cultured by serum collected after exercise in vitro(i.e.,the cultivation of cancer cell lines in an experimental setting,which simplifies the biological system and provides mechanistic insight into cell responses).The underlying mechanisms of exercise-induced cancer suppressive effects may be attributed to the alteration in circulating factors,such as skeletal muscle-induced cytokines(i.e.,myokines)and hormones.However,exercise-induced tumor suppressive effects and detailed information about training interventions are not well investigated,constraining more precise application of exercise medicine within clinical oncology.To date,it remains unclear what role different training modes(i.e.,resistance and aerobic training)as well as volume and intensity have on exercise-condi-tioned serum and its effects on cancer cells.Nevertheless,the available evidence is that a single bout of aerobic training at moderate to vigorous intensity has cancer suppressive effects,while for chronic training interventions,exercise volume appears to be an influential candidate driving cancer inhibitory effects regardless of training mode.Insights for future research investigating training modes,volume and intensity are provided to further our understanding of the effects of exercise-conditioned serum on cancer cells.

Exercise training in heart transplantation

Heart transplantation remains the gold standard in the treatment of end-stage heart failure(HF).Heart transplantation patients present lower exercise capacity due to cardiovascular and musculoskeletal alterations leading thus to poor quality of life and reduction in the ability of daily self-service.Impaired vascular function and diastolic dysfunction cause lower cardiac output while decreased skeletal muscle oxidative fibers,enzymes and capillarity cause arteriovenous oxygen difference,leading thus to decreased peak oxygen uptake in heart transplant recipients.Exercise training improves exercise capacity,cardiac and vascular endothelial function in heart transplant recipients.Pre-rehabilitation regular aerobic or combined exercise is beneficial for patients with end-stage HF awaiting heart transplantation in order to maintain a higher fitness level and reduce complications afterwards like intensive care unit acquired weakness or cardiac cachexia.All hospitalized patients after heart transplantation should be referred to early mobilization of skeletal muscles through kinesiotherapy of the upper and lower limbs and respiratory physiotherapy in order to prevent infections of the respiratory system prior to hospital discharge.Moreover,all heart transplant recipients after hospital discharge who have not already participated in an early cardiac rehabilitation program should be referred to a rehabilitation center by their health care provider.Although high intensity interval training seems to have more benefits than moderate intensity continuous training,especially in stable transplant patients,individualized training based on the abilities and needs of each patient still remains the most appropriate approach.Cardiac rehabilitation appears to be safe in heart transplant patients.However,long-term follow-up data is incomplete and,therefore,further high quality and adequately-powered studies are needed to demonstrate the long-term benefits of exercise training in this population.

Physiological and perceptual responses to sprint interval exercise using arm versus leg cycling ergometry

Increases in power output and maximal oxygen consumption(V_O2max)occur in response to sprint interval exercise(SIE),but common use of“all-out”intensities presents a barrier for many adults.Furthermore,lower-body SIE is not feasible for all adults.We compared physiological and perceptual responses to supramaximal,but“nonall-out”SIE between leg and arm cycling exercise.Twenty-four active adults(mean±SD age:[25±7]y;cycling VO_(2)max:[39±7]mL·kg^(-1)·min^(-1))performed incremental exercise using leg(LCE)and arm cycle ergometry(ACE)to determine VO_(2)max and maximal work capacity(Wmax).Subsequently,they performed four 20 s bouts of SIE at 130% Wmax on the LCE or ACE at cadence=120-130 rev/min,with 2 min recovery between intervals.Gas exchange data,heart rate(HR),blood lactate concentration(BLa),rating of perceived exertion(RPE),and affective valence were acquired.Data showed significantly lower(p<0.001)absolute mean([1.24±0.31]L·min^(-1) vs.[1.59±0.34]L·min^(-1);d=1.08)and peak VO_(2)([1.79±0.48]L·min^(-1) vs.[2.10±0.44]L·min^(-1);d=0.70)with ACE versus LCE.However,ACE elicited significantly higher(p<0.001)relative mean([62%±9%]VO_(2)max vs.[57%±7%]VO_(2)max,d=0.63)and peak VO_(2)([88%±10%]VO_(2)max vs.[75%±10%]VO_(2)max,d?1.33).Post-exercise BLa was significantly higher([7.0±1.7]mM vs.[5.7±1.5]mM,p=0.024,d?0.83)for LCE versus ACE.There was no significant effect of modality on RPE or affective valence(p>0.42),and lowest affective valence recorded(2.0±1.8)was considered“good to fairly good”.Data show that non“all-out”ACE elicits lower absolute but higher relative HR and VO_(2) compared to LCE.Less aversive perceptual responses could make this non-all-out modality feasible for inactive adults.

High intensity interval training and molecular adaptive response of skeletal muscle

Increased cardiovascular fitness,VO_(2max),is associated with enhanced endurance capacity and a decreased rate of mortality.High intensity interval training(HIIT)is one of the best methods to increase VO_(2max)and endurance capacity for top athletes and for the general public as well.Because of the high intensity of this type of training,the adaptive response is not restricted to Type I fibers,as found for moderate intensity exercise of long duration.Even with a short exercise duration,HIIT can induce activation of AMPK,PGC-1α,SIRT1 and ROS pathway as well as by the modulation of Ca^(2+)homeostasis,leading to enhanced mitochondrial biogenesis,and angiogenesis.The present review summarizes the current knowledge of the adaptive response of HIIT.