Physical Activity and Intermittent Exercise Training for Cardiovascular and Cognitive Gain in Obese Women
Condition: Obesity; Cognitive Ability, General; Cardiovascular Disease
MeSH terms: Cardiovascular Diseases
Study type: Interventional

Summary: 
      One hundred participants from a combination of (a) local advertisements and/or (b) those
      whose details are held on a research database (of previous volunteers indicating willingness
      to be contacted about future studies) will be sought to volunteer for this study. Written
      informed consent will be gained following greater than 48 hours for the purpose of reading
      the Participant Information sheets. The study will then involve two stages (i) recruiting
      participants for a cross sectional analysis of the relationship between physical activity
      levels and cardiovascular and cognitive function, and (ii) a longer exercise training study
      in a subsample of these volunteers (i.e. participants who volunteer to exercise train).
      Participants for stage 1 will then visit the laboratory in the University on three occasions
      (over a three week period) to be assessed for body composition, exercise tolerance, current
      physical activity levels, cognitive function and arterial and cardiac health. Each visit will
      last for 60 - 90 minutes. Participants will then be provided with an accelerometer to wear
      for a period of one week in order to assess movement counts and sedentary behaviour. Stage 2
      will include only those participants who have volunteered for the exercise training component
      (approx 60). These participants will then be randomly divided into two groups. Both groups
      will exercise three times per week for 12 weeks duration. Group 1 will exercise in a
      traditional manner at a moderate intensity, whilst the second group will exercise at a heavy
      intensity but in short bursts. Both groups will complete the same amount of work but in two
      differing modes. Both groups will attend the laboratory twice per week for supervised
      exercise sessions and also perform one home based 30 minute brisk walk per week. All
      participants will be re-examined at 12 weeks.
    

Detailed description: 
      The study will involve two stages (i) recruiting participants for a cross sectional analysis
      of the relationship between physical activity levels and cardiovascular and cognitive
      function, and (ii) a longer exercise training study in a subsample of these volunteers. 100
      participants for stage 1 will visit the laboratory in the University on three occasions
      (within a three week period) to be assessed for anthropometric outcomes, body composition,
      exercise tolerance, cognitive function and arterial and cardiac health. Each visit will last
      for 60 - 90 minutes. Participants will then be provided with an accelerometer to wear for a
      period of one week in order to assess movement counts and sedentary behaviour. Stage 2 will
      include only those participants who are happy to continue into the exercise training phase.
      These participants will then be matched for age and BMI and then randomly (on matched pairs)
      allocated to one of two groups. Both groups will exercise three times per week for 12 weeks
      duration. Group 1 will exercise in a traditional manner undertaking continuous exercise,
      whilst the Group 2 will exercise at a heavy intensity but in short bursts (interval
      exercise). Both groups will complete the same amount of work but in two differing modes. Both
      groups will attend the laboratory twice per week for supervised exercise sessions and also
      perform one home based 30 minute brisk walk per week. All participants will be re-examined at
      12 weeks.

      Recruitment of participants

      One hundred participants from a combination of (a) local advertisements and/or (b) those
      whose details are held on a research database (of previous volunteers indicating willingness
      to be contacted about future studies) will be sought to volunteer for this study.
      Participants will be contacted via email/telephone/letter to provide information regarding
      this study. All volunteers interested in participating will be contacted to provide general
      information during a preliminary telephone screening interview. This will be used to check
      main inclusion and exclusion criteria. The women who fit these criteria will be sent the
      participant information sheet to read carefully and if still interested invited to attend the
      first laboratory visit for a screening session. Participants have greater than 48 hours to
      assess the participant information sheet before they attend this first visit when, if
      eligible, they will be asked to provide written informed consent.

      Laboratory Visits

      Visit 1

      During this visit the study and all procedures will be explained in detail to all
      participants, and written informed consent will be taken. A thorough medical history will be
      obtained and participants will be asked to complete a Recruitment Information Questionnaire
      (RIQ) to confirm all inclusion/ exclusion criteria. Participants will complete the National
      Adult Reading Test (NART) which estimates premorbid intelligence levels.

      Participants will also complete a Physical Activity Readiness Questionnaire (PAR-Q) which
      will be reviewed to determine whether participants are fit to continue with the study. Simple
      measures of body weight, height and waist circumference will be taken. Participants will
      complete a practice version of the cognitive test battery to demonstrate the tests, ensure
      participants understand how to perform the tests correctly and assess compliance (effort).

      Participants will complete a cycling test on a stationary bicycle under the supervision of
      the investigator and a medic.

      Visit 2

      The second visit will involve several measures of arterial health which requires participants
      to attend in a 12 hour fasted state. Blood vessel function will be assessed using a blood
      pressure cuff around the lower arm for a period of 5 minutes. Cardiac structure and function
      will be assessed using two-dimensional (2D) echocardiography. Vascular function will be
      assessed using ultrasound and applanation tonometry. All procedures are non-invasive.
      Percentages of body fat and muscle mass will be measured using bioimpedance.

      A 60ml blood sample will be taken which will be used to asses endothelial progenitor cell
      number and function, insulin sensitivity, cholesterol levels and is part of the assessment
      for health of the arteries and vascular system.

      Visit 3

      On the third visit a cognitive function test will be completed, which requires participants
      to attend in a 12 hour fasted state.

      Participants will perform a 45 minute battery of cognitive tests. Following the cognitive
      tests, participants will be asked to complete a cognitive test evaluation questionnaire to
      assess both subjective and objective cognition.

      At the end of the third laboratory visit all participants will be provided with an ActiHeart
      accelerometer (Actigraph, Pensacola, USA) to wear for a period of one week in order to assess
      movement counts and sedentary behaviour. At the end of the seven days the accelerometer is
      given back to or collected by the team and the data downloaded.

      The three baseline laboratory visits plus the seven days using the ActiHeart accelerometer
      all come under stage 1 of the study. Participants will be asked to continue into the exercise
      training stage (stage 2), and willing volunteers will move through to the second stage of the
      experiment. All measures will be repeated at 12 weeks (78 hours to 5 days following cessation
      of the last exercise training session).
    

Intervention name(s): Interval exercise training; Continuous exercise training (CON)
Intervention type(s): Behavioral; Behavioral
Intervention description(s): Interval exercise sessions (INT) involving work:recovery ratios of 40 s at 70% delta work-rate followed by 80 s active recovery at 20 W. 70% delta (∆) is 70% of the difference between work rate peak (WRpeak) and work rate at the lactate threshold (WRLT) calculated as:
70%∆ =0.7(〖WR〗_peak- 〖WR〗_LT )+ 〖WR〗_LT
Where WR is work rate, LT is lactate threshold)
Each session was for 30 min and this was undertaken twice per week for 12 weeks. One home based exercise session was incorporated per week.; Exercise sessions involved cycling at 20%∆ work-rate peak for the duration of the session. This work-rate was chosen so that all participants in the group would be exercising in the heavy-intensity domain. To enable participants in the CON exercise group to complete the same amount of work (kJ) as the participants in the INT exercise group, the amount of work that would be completed if the CON participants completed an INT exercise session was calculated. Participants exercised for 26 min (varying to match interval group) twice per week for 12 weeks.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Prevention