Heart Rate During Exercise in Type 2 Diabetes
Condition: Type2 Diabetes Mellitus; Hyperglycemia; Heart Rate; Exercise Training
MeSH terms: Diabetes Mellitus; Diabetes Mellitus, Type 2; Hyperglycemia
Study type: Interventional

Summary: 
      Exercise training is a cornerstone for the prevention and treatment of metabolic disorders
      and associated cardiometabolic complications such as type 2 diabetes mellitus (T2D) and
      hypertension. Similar to the beneficial health effects after performing conventional
      continuous exercise modalities, high intensity interval training (HIIT) has been reported as
      an effective alternative exercise-modality to improve glucose homeostasis in both prediabetes
      subjects and individuals with T2D diagnosed. In this regard, although multiple HIIT-based
      interventions commonly report acute and long term benefits on body composition,
      cardiorespiratory fitness and insulin sensitivity in metabolically compromised subjects,
      little is known about the acute cardiovascular response (i.e., at heart rate level) during
      HIIT in subjects with different glucose control.

      HIIT is described as performing brief periods of exercise at vigorous or maximal intensity,
      interspersed with inactive or low intensity recovery phases of variable duration. In order to
      characterize different HIIT-based protocols, exercise intensity is usually defined as
      relative percentages of individual maximal cardiorespiratory fitness (VO2max) or relative
      maximal power output values. Nevertheless, the need for specific technological equipment to
      assess these parameters usually limit the prescription and recommendations of HIIT in
      clinical settings and other public health contexts at massive level. Additionally, the use of
      self-perceived exertion scales and heart rate (HR) variations upon HIIT have been
      demonstrating to be accessible and feasible strategies to regulate exercise intensity during
      HIIT. For example, it was reported that HR and self-perceived exertion scores increased
      progressively in T2D subjects, parallel to the oxygen consumption rate throughout an acute
      HIIT session performed on cycle ergometer. Consequently, it is conceivable to hypothesize
      that determining HR variations during HIIT might optimize the recommendation of this training
      methodology in metabolically compromised subjects as those at risk or with T2D diagnosed.
      Therefore, the aim of the present study was To describe and compare the acute heart rate
      changes in response to an incremental maximal exercise test and a single HIIT session between
      normoglycaemic (NG), prediabetes (Pre-T2D) and type 2 diabetes mellitus (T2D) subjects.
    

Detailed description: 
      This cross-sectional study will use a non-probabilistic sample of 75 adult subjects,
      characterized as healthy normoglycaemic and others with disturbed glucose homeostasis
      subjects, all referred by a physician to the exercise programme of our research centre. The
      present study will be carried out in accordance with the Declaration of Helsinki and was
      approved by the Scientific Ethics Committee of the Universidad de La Frontera. All volunteers
      read and signed an informed consent. The inclusion criteria will be; a) aged 18-60 y; b)
      previously screened by physician professional; c) diagnosed with normoglycaemic, prediabetes
      or T2D state; d) and living in Temuco city. The exclusion criteria will be; a) low maximal
      cardiorespiratory fitness (defined as VO2max ≤21 ml/kg-1/min-1) below the expected value for
      the subject's sex and age 11; b) not receiving pharmacologic hypotensive treatment with
      β-blockers; and c) having no musculoskeletal limitations to perform exercise cycling. The
      total sample size will be divided in three groups according to the standard glycaemic
      classification 12; normoglycaemic (NG, n = 32), pre-diabetes (Pre-T2D, n = 30) and type 2
      diabetes (T2D, n = 13). The study considered three stages of measurements (enrollment,
      exercise test, single HIIT session).
    

Intervention name(s): Behavioral; Exercise training intervention
Intervention type(s): Other; Other
Intervention description(s): The resting heart rate (HRrest), maximum HR (HRmax), HR recovery (HRRTEST), delta HR recovery (ΔHRRTEST) were measured by continuous telemetric heart rate sensor (Polar FT4, PolarTM, Finland) during an incremental exercise test designed to obtain maximum oxygen consumption (VO2max) on a cycle ergometer (Lode Corival, Groningen, The Netherlands) similar with previous studies using similar cohort. An indirect calorimetry/ergospirometry system (Ultima CPXTM metabolic system, Medgraphics, Minnesota, USA) was used to measure VO2max until volitional exhaustion. Thus, the modified Astrand volitional protocol was applied in the participants of all NG, Pre-T2D and T2D groups increasing the load (i.e., Watts) 25 W each 2 min to women, and 50 W each 2 min to men.; Subjects also participated in a single HIIT session composed of 10-cycling intervals, using a Lode Corival cycle ergometer. The exercise session consisted of 1-minute cycling at high intensity (workload during each interval was set at ~80-100 % maximal power achieved during the incremental exercise test with a workload that allowed to work until the volitional muscle failure in 1-minute), followed by 2-minutes of inactive resting period (sitting still on the cycle ergometer), and was repeated 10 times (1x2x10 protocol; 1:2:10 to work:rest:repetitions respectively).
Other intervention name(s): Incremental exercise test; Exercise training intervention with HIIT
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: We will compare a type 2 diabetes mellitus group during exercise, with another hyperglicaemic, and normoglicaemic group in the heart rate maxymum.
Masking: Single (Investigator)
Primary purpose: Prevention