Aerobic Interval Training v/s Resistance Interval Training On Ejection Fraction In Stable Post MI Patients
Condition: Myocardial Infarction
MeSH terms: Myocardial Infarction; Infarction
Study type: Interventional

Summary: 
      Randomized controlled trial (single blinded) study was conducted on 26 stable Post MI
      patients according to inclusion and exclusion criteria aged 35 to 65 years. Study was
      conducted in Rawalpindi Institute of cardiology and Pakistan Railway Hospital from July 2016
      ---- December 2016.Participants was randomly allocated in control or experimental group by
      lottery Method. Informed consent was signed by each participant prior to enrolment. Patients
      in both group received standard treatment that is Aerobic Interval training whereas patients
      in interventional group received additional Resistance training. Post echocardiography and
      lipid profile was done to assess the effect of intervention on ejection fraction, cholesterol
      and triglycerides. The standard questionnaire Mac New QLMI was used to assess quality of
      life. The data was analyzed on SPSS 21
    

Detailed description: 
      It is already established worldwide that myocardial infarction is one of the leading cause of
      morbidity and mortality. According to WHO (2008), cardiovascular diseases account for one
      third of annual deaths. Globally over 17 Million deaths occur each year due to coronary
      artery diseases. In United States of America, CAD has affected more than 13 million of the
      population in the year 2003 including almost 860, 000 people with acute MI, whereas 480,000
      people lost their lives due to CAD. The prevalence of coronary artery disease in a population
      can be estimated by incidence of MI in that population.

      However, in the past few decades cardiovascular disease rates have considerably decreased in
      high income countries, but on the other hand have increased in low and middle income
      countries with 80 percent of global burden of disease in these countries. Global strategy is
      therefore required to educate about the importance of risk factors in prevention of disease,
      disability and death and improving clinical outcomes to prevent recurrent event.

      Myocardial infarction can be a tragic and a disastrous event leading to sudden death or it
      can also be a minor event which may even go undetected. Patients who once have MI, always
      have a chance to get it over and over again.The incidence rate of MI increases with age,
      particularly after 45 years in men and after 55 years in women. Recurrent infarctions were
      found more frequent in women than men. First infarction sometimes goes unrecognized but
      recurrent infarctions were almost always easily recognized.

      One of the major complications affecting patient lifestyle after CABG is depression. It
      affects almost 30 to 40% of the patients undergoing surgery. Evidence also suggests that
      depression after surgery was more common among those patients who were depressed prior to
      surgery too. Depression along with anxiety can increase the risk of mortality and morbidity
      independently without involving any medical cause. Depression and anxiety although do not
      have that much effect on neuropsychological dysfunction but the risk of disorientation and
      confusion leading to delirium is increased. Therefore, psychological counseling of patients
      should be done before surgery to reduce the risk of depression following surgery in order to
      improve overall quality of life of patient.

      Cardiac rehabilitation after discharge from hospital is phase 2 or outpatient cardiac
      rehabilitation. Phase 2 Rehabilitation is under complete supervision of cardiologist along
      with physiotherapist, exercise therapist and nurse. Blood pressure and heart rate are
      monitored at rest during and after exercise session along with ECG monitoring. Phase 2
      includes aerobic training that includes treadmill and cycling together with resistance
      training that can be with hand grippers and weights. Recommended guidelines of exercises are
      followed which varies according to patients condition and response. Total exercise session is
      of 50- 60 minutes, prescribed weeks of exercise in low, moderate and high risk patients is of
      4, 6 and 8 weeks respectively. Patients are also educated for modification of risk factors,
      nutritional counseling, weight control and stress management. After competition of phase 2,
      patients are encouraged to enter maintenance phase that is phase 3.

      For an exercise prescription plan, heart rate and metabolic equivalent [1 MET=3.5mL
      02/kg/min] is set at 50-80% of the peak during exercise stress testing, or heart rate of 10
      or >10 bpm below the ischemic ECG (^0.1 mV), or anginal threshold. In patients who are not
      tested by exercise testing, 20- 30 beats above their resting heart rate is considered to be
      the target heart rate. For intensity guide along with heart rate RPE (6-20 scale) is also
      used. In early stage of phase 2 rehab 11- 13 is considered upper limit for training. However
      for phase 3, 12- 14 is upper limit and considered safe.

      The exercise plan should be individualized according to patient capacity, risk factors and
      co-morbidities. The universal guidelines of exercise should be followed. Exercise should be
      started with warm up, followed by prescribed exercise like aerobic and interval training and
      ending session with cooling to stable patient. Continuous monitoring of vitals is necessary
      in MI patients during exercise. The progression of exercise is increasing the intensity of
      exercise with following weeks according to patient's capacity.

      In athletes to gain aerobic and anaerobic health, interval training at 75% VO2 max is usually
      beneficial than traditional continuous training. More recently interval training is
      introduced. Many studies are done on efficacy and safety of interval training in coronary
      artery patients but data is still lacking. Furthermore studies are required with larger
      samples for safe dosage and prescription of interval training in cardiac patients.

      Aerobic interval training was found to be more effective than conservative continuous
      training at moderate intensity in reversing myocardial remodeling post MI as it increases
      myocardial contractility which has positive effect on ejection fraction, stroke volume and
      ejection velocity.

      One of the studies done by Ehsani in 2007 has found that two of the major factors in
      remodeling post MI that is resting diastolic diameter and volume of LV decreased in both
      training groups. While other three factors responsible for increasing heart contractility
      like ejection fraction, stroke volume and cardiac output only increased in interval training
      group. In comparison to aerobic training, interval training has no safety hazard. The
      improvement of muscle strength, body strength and overall cardiac fitness is even better than
      traditional aerobic training.

      Previously only aerobic training was considered safe in coronary artery diseases patients.
      Resistance training beneficial effects in heart diseases were not established previously
      considering that resistance training can be harmful as they can cause further ischemia or
      unlikely events like arrhythmias, especially isometrics were not considered safe in MI
      patients as many studies reported that they can cause life threatening events like
      arrhythmias. Previously one of the other reasons for contraindication of resistance training
      was increased after load causing adverse effect on left ventricular function but recently
      studies had confirmed that resistance exercise can be an effective mean of therapy in cardiac
      patients as it has no negative effect on left ventricular function.

      After acute MI, resistance exercises are absolutely contraindicated for 2-3 weeks .They can
      be started slowly after 3 weeks with very low weight of 1-2 lbs with a recommended safe dose
      of 10-15 reps performed on alternating days and a maximum RPE of 12 to 13. Intensity
      increases according to individual patient. After 6 weeks of myocardial infarction have
      passed, weight machines and barbells can be used as a part of resistance training program.
      Plan of resistance exercises in cardiac patients should be individualized to each patient
      according to their CV status co-morbidities and degree of LV dysfunction. One of the
      recommended guidelines for resistance exercises is 2-3 days a week with moderate to high
      intensity for almost 3-6 months.

      Comparison of heart rate and systolic blood pressure changes in cardiac patients during
      aerobic and resistance training was done. The study showed that peak heart rate was 12%
      greater than target heart rate during aerobics whereas on other hand it was 12% less than
      target heart rate during resistance training. Blood pressure monitoring at end of both
      trainings showed increase in systolic BP was slightly greater than aerobic training.

      Many factors contribute to development of atherosclerosis. The role of lipid profile in
      development of coronary artery diseases in past few decades has been well established The
      benefits of physical activities are various one of the positive effect seen is on lipid
      profile with increase in HDL and decrease in total cholesterol and triglycerides alone or
      together with dietary modifications which are essential component. Aerobic training at
      moderate to high intensity variably cause an improvement in lipid profile Studies have shown
      that reduction in triglycerides were seen more in males in comparison to females.

      Exercise at low training can also decrease triglycerides from 8 to 20 mgdl with minimum
      exercise of 24 to 32 km/week and caloric expenditure of 1200 to 2200 Kcal/week. Exercise that
      reaches this minimum range can produce positive lipid changes.

      Combined Strength and aerobic training of 8 months can make positive biochemical and muscular
      accommodation on total cholesterol triglycerides as well as on HDL. However the changes are
      reversed with three months of detraining concluding that exercise should be integral part of
      life as it plays vital role to prevent coronary artery disease.

      Exercise training as an integral component of cardiac rehabilitation is intended to restore
      health and fitness to patients suffering from heart diseases. It has a favorable effect on
      numerous cardiac and health related outcomes. Left ventricle impairment is a substantial
      prognostic indicator of mortality. Particularly for coronary heart disease patients, one of
      the clinical predictors of long-term prognosis is left ventricular ejection fraction (LVEF)
      which is a marker of myocardial contractility. Ejection fraction is the quantity of blood
      pumped by the left ventricle of heart per minute into the aorta which is the largest artery
      in the body. LVEF ≥ 50% is deemed normal, also termed as preserved ejection fraction.
      Ejection fraction falls considerably after MI and cardiac surgeries such as CABG and valve
      replacement surgeries. In these patients who undergo heart surgery, phase I cardiac
      rehabilitation plays a significant role in improving the hemodynamic variables such as
      ejection fraction.

      The effectiveness of phase I cardiac rehabilitation in cardiac surgeries is well-established.
      But regarding phase II, there is a paucity of accurate data on the effectiveness of various
      types of exercise training on LVEF in coronary artery disease patients. Most of the studies
      conducted previously, have explored the impact of exercise on ejection fraction in heart
      failure patients, whereas methodological disparities are evident in the ones conducted on CAD
      patients. Therefore, attention is being focused towards this aspect for the past few years.
      It was found that a 12 weeks structured, individually adapted exercise plan, if started early
      i.e. within one month after discharge, could considerably improve left ventricle function in
      terms of LVEF in CAD patients. After consultation with the rehab specialist, the exercise
      plan could also be carried out at home, if access to a clinical setting is difficult. As
      impaired LV systolic function is an absolute predictor of mortality in myocardial infarction,
      hence utilizing cardiac rehab and secondary prevention for improving ejection fraction would
      result in better survival chances.

      My current study aim was to evaluate and find out whether the combination of Resistance
      interval training and Aerobic interval training is more effective than Aerobic interval
      training alone in improving EF in Post Stable MI patients. This study will add to literature
      and fill the gap as most studies previously done was on Aerobic interval training in CAD .
      More over no study has individually focused on post MI patients without surgical
      interventions. Furthermore No research up to date has compared Aerobic interval training with
      Resistance interval training in improving EF after MI.
    

Intervention name(s): Aerobic Interval Training; Aerobic + Resistive Interval Training
Intervention type(s): Other; Other
Intervention description(s): Aerobic Interval Training Patients in this group will perform 6 minutes of cycling followed by 3 minutes of pause and again 6 minutes of cycling followed by 3 minutes of pause and finally 6 minutes of treadmill followed by 3 minutes of rest.
both groups will perform cool down exercises that include again breathing exercises, stretching and active exercises.; Aerobic + Resistive Interval Training Patients in this group; first set will perform 3 minute of cycling ,1 set of hand grippers 1.5 to 2.5 lbs (10 to 12 reps) and 1 set of biceps resistive exercises 1 Kg to 3 kg (10 to 12 reps) followed by 3minute of pause. In second set patient will perform 3 minutes of stationary cycling , 1 set of quadriceps resistive exercises 1 to 3 Kg (10 to 12 reps) again followed by 3 minutes of pause and in third set patient will perform 3 minutes of treadmill walk at 1.5 to 4 speed, and 1 set of standing ankle pumps (10 to 12 reps).
both groups will perform cool down exercises that include again breathing exercises, stretching and active exercises.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Investigator)
Primary purpose: Other
Keywords: Aerobic Interval training; Ejection Fraction; Myocardial Infarction; Resistive Interval Training