The Effect Of High Intensity Interval Exercise On Blood Pressure,heart Rate Recovery And Serum Troponin Level And Training Adaptation In Obese Young Women

High-intensity interval training?HIIT?involves repeated short-to-long bouts of rather high-intensity exercise interspersed with recovery periods.The HIIT is today one of the most popular means of improving cardiorespiratory and metabolic function.However,it is still unclear whether different forms of HIIT would result in different responses and adaptations in hemodynamics and cardiac autonomic recovery.In addition,safety of high-intensity interval exercise?HIIE?has been concerned regarding its cardiac risk due to its high intensity.Further insights into response and adaptation of hemodynamics and cardiac injury biomarker appearance to interval exercise will is necessary to facilitate informed clinicians and exercise prescriptions.Consequently,the aims of the present study were to investigate the effects training of three forms of HIIE on blood pressure?BP?,heart rate recovery?HRR?and cardiac troponin T?cTnT?responses to acute respective exercise and training adapation.Experiment 1Purpose:This experiment characterized BP and HRR responses to three forms of HIIE and determined the impact of training progression on the BP and HRR response to acute exercise.Methods:Fifty-four sedentary obese young women were randomized to HIE training(repeated 4-min cycling at 90 VR _2maxmax interspersed with-min rest,200 k??session,HIIT90),work-equivalent sprint interval exercise training(repeated 1-min cycling at 120 VR _2maxmax interspersed with 1.5-min rest,HIIT120),repeated sprint exercise training?40�6-s all-out sprints interspersed with 9-s rest,SPRINT?,or control group?C N?.BP was assessed before and 5 min,15 min and 0 min after the 1st,6th,20th,and 44th training session,respectively.BP and HRR also were assessed immediately after each exercise bout during the four training sessions in HIIT90 and HIIT120 groups.Results:Acute HIIE in three groups led to elevated systolic BP?by 20�2 mmHg,P<0.05?during exercise and post-exercise hypotension independent of training progression and forms.SPRINT training resulted in reduced resting systolic BP from 6th?P<0.05?and got to plateau at 20th.In HIIT90 group,systolic BP and HRR during the 20th and 44th was significantly higher?P<0.05?than the corresponding value during 1st,respectively.Experiment 2Purpose:This experiment characterized cTnT responses to three forms of HIIE and determined the impact of training progression on the cTnT response to acute exercise.Methods:Thirty-six sedentary obese young women were randomized to HIIT90,HIIT120 and SPRINT group.cTnT was assessed using a high sensitivity assay before and immediately,and 4 h after the 1st,6th,20th,and 44th training session,respectively.Results:In all three groups,cTnT was significantly elevated after 1st and 6th?P<0.05?with no between-group differences between HIIT90 and HIIT120,but the cTnT elevation after 1st in HIIT90 and HIIT120 was higher than that in SPRINT?P<0.05?.20th 44th had no significant effect on post-exercise cTnT concentration?P>0.05?.Conclusions?1?Three forms of HIIE led to a small increased BP during exercise and post-exercise hypotension.?2?SPRINT and HIIT90 training might reduce and elevate the resting and exercise BP,respectively.?3?HIIT90 training elevated HRR during exercise,suggesting this training may improve vagal reactivation.?4?Equal-work HIIT90 and HIIT120 induced similar cTnT elevation,and a lower,but substantial,cTnT increase also occurred after lower-work SPRINT with 4-min exercise duration.?5?In all three training regimes,an elevated post-exercise cTnT could be expected in the early stages of training,but exercise-induced elevation in cTnT would be gradually abolished with increased exposure to interval exercise.The cardiac risk of three training regimes is low and training progression further reduce the risk.