Glycemic Responses and of the Autonomic Cardiac Function in Diabetes Type-2 Women Post Resistance Exercise
Condition: Diabetes Mellitus; Autonomic Diseases
MeSH terms: Autonomic Nervous System Diseases; Diabetes Mellitus; Diabetes Mellitus, Type 2
Study type: Interventional

Summary: 
      The aim of this study was to investigate and correlate the glucose responses and VFC 24 hours
      after resistance exercise (RE) sessions at different intensities in women with type 2
      diabetes (DM-2). Twelve women with DM-2 were invited to perform by one week in randomized
      order, two weeks interventions with experimental sessions: Session Control (CONT) without
      conducting RE, RE session (40% or 80% of one maximum repetition - 1RM) on day 2 and day 3 was
      observed the effect of the length of RE session by 11h. After that, initiated the
      experimental sessions, where after each of the analysis of glucose 24h by continuous
      monitoring system of glucose was performed, considering breakfast, lunch, dinner and sleep,
      and analysis performed of the RR series by a period of 48h. During control sessions, the
      subjects were seated comfortably for 40min and RE sessions, 40%1RM and 80%1RM, were performed
      in medium circuit 3 sets with 16 and 8 replications and recovery range between 60 exercises
      and 90seg , respectively, and between the circuits 120sec. It was observed that the
      concentration of glucose in the period of 24h after the session has been reduced to 40% 1RM
      vs. CONT and 80%1RM. Hyperglycemia was prevalent in the period 34h of the sessions CONT and
      80%1RM, respectively , being different from the session 40%1RM. In postprandial times,
      shorter hyperglycemia was found in the session to 40% 1RM vs. CONT and 80% 1RM after
      breakfast, lunch and dinner. At the time of sleep, less time in hyperglycemia was found
      between sessions of 40% 1RM vs. 80% 1RM. Significant correlations (p <0.01) were found
      between glucose 24h with cardiac autonomic RRi variables, HF, LF and reason LF:HF.
    

Detailed description: 
      This study was a randomized cross-by blocks in accordance with CONSORT (Schulz et al., 2010).

      In total, 12 women with DM-2, between 48 and 60 years old participated in the study, where
      they were informed of risks, benefits and objectives of the study and signed a consent form
      Clarified (IC) previously approved by the Ethics Committee and Ethics in Research and Studies
      (CEDEP) of the Federal University of São Francisco Valley (UNIVASF), Petrolina - PE, Brazil
      (No. 0005/180814 CEDEP).

      Of the participants, 11 were taking oral hypoglycemic medication (metformin [n = 7],
      Sulphonylurea [n = 1] Metformin in combination with sulfonylurea [n = 3]) and performed only
      dietary control.

      Before the first visit to the UNIVASF Exercise Physiology Laboratory, the participants
      underwent a resting ECG examination, which could only be submitted to the test of a one
      maximum repetition (1RM) and meetings after report of normality certified by cardiologist.

      On the first visit to the lab, participants responded history about health history, physical
      activity level and risk stratification. Subsequently were performed anthropometric
      measurements of waist circumference, abdomen and hip, as well as height and body mass for
      subsequent calculation of body mass index.

      Two weeks before starting the intervention, participants underwent familiarization with the
      exercise protocol for three alternate days. After 48 hours was performed the 1RM test in the
      following exercises: bench press on the machine (pectoral and anterior deltoid muscle),
      extensor chair (quadriceps muscle), Flying (pectoral muscle), flexor chair (muscle biceps
      femoris, semitendinosus and semimembranosus), Pull High ahead (posterior muscles of the torso
      and biceps), leg press (quadriceps and gluteus), sitting Remada (posterior muscles of the
      torso and biceps) in equipment of Evidence® mark (Cachoerinha / RS - Brazil) and Physicus®
      (Auriflama / SP - Brazil).

      After the 1RM test, participants received guidance in relation to food intake and the
      practice of daily physical activity, and that, 48 hours before the first day of intervention,
      do not ingest drinks contained alcohol and caffeine.

      In the days of the sessions, participants fasted, they went to the lab, where they received a
      standard breakfast containing 285 kcal, 45g and (180 kcal) carbohydrate, 6 g (24 kcal) of
      protein and 9 g (81 kcal) of fat. Also they were asked to maintain the same diet during the
      two-week intervention and record consumption in a food diary, which was later analyzed and
      calculated by a trained nutritionist, using Microsoft Excel® software and the Brazilian Table
      of Food Composition.

      It was also recommended that the main meals were taken at the same time of day (Breakfast
      between 7:00 and 7:20h; lunch between 12:00h and 14:00h and Dinner between 18:00h and
      20:00h). The energy intake and consumption of daily macronutrients did not differ between
      sessions as shown in Table 2. During the days of intervention participants were instructed to
      refrain from any exercise and / or strenuous physical labor.

      The glucose sensor (Sof-sensor, Medtronic Minimed, Inc., Northridge, CA, USA) has been
      installed the day before the first session being inserted following manufacturer's
      instructions SMGG Guardian real-time (Medtronic Minimed, Inc., Northridge CA, USA), which
      consists of a transmitter sensor inserted through a needle into the abdominal subcutaneous
      tissue using a device (Sen-Seter, Medtronic Minimed, Inc., Northridge, CA, USA) and a monitor
      for reading with wireless radio frequency sensor. This system has been validated in DM
      control studies and complications.

      After the installation, there were appropriate calibration of the equipment following the
      manufacturer's recommendations. During the monitoring period, capillary glucose samples were
      collected using a glucose monitor (Accu-Check Performa, Roche Diagnostics, Mannheim, Germany)
      to calibrate the SMCG, being held four times every 24 hours monitoring by the researcher.
      Participants were blinded with regard to measurements of SMCG and capillary glucose during
      calibrations.

      The glucose concentrations were analyzed on day 1 (24 hours analysis to observe the effect of
      the control section), Day 2 (24h analysis to observe the effect of Resistance Exercise - RE
      on different intensities) and day 3 (11h analysis of the duration of effect RE at different
      intensities).

      To evaluate the autonomic modulation is adopted the frequency meter of Polar® RS800CX model
      (Electo Oy, Kempele, Finland) with proven validity and reproducibility (Essner et al, 2013;
      Jonckheer-SHEEHY et al, 2012.).

      The investigated autonomic indicators were: 1) straight-time domain from absolute average
      records of RR intervals (RRi) and; 2) the frequency domain method for spectral analysis by
      Fast Fourier Transformer (low frequency - LF normalized units as a marker of sympathetic
      activity, high frequency - HF also with normalized units as a marker of vagal activity, and
      the LF:. HF as a marker of sympathovagal balance). All indexes are described by the European
      Society of Cardiology (TASK FORCE HEART Variability, 1996) and all Analyses were performed in
      Kubios HRV Analysis Software version 2.0 (Biosignal Laboratory, University of Kuopio,
      Finland).

      All participants took part in a randomized experimental study, which consisted of two
      intervention periods, with each period consisted of three days where on day 1 a control
      session (CONT) was held, day 2 to RE session (40% 1RM or 80% 1RM), day 3 to check the
      duration of the effect of exercise. Each intervention aimed to assess the impact of a workout
      on glycemic control in standardized food and free living conditions.

      Initially the participants arrived at the laboratory in fasting at 7: 00 and at that time was
      provided to them a standardized breakfast containing 285kcal, breakfast period was between 7:
      00 - 7: 20h. After this period, the volunteers were instructed again on the subsequent power
      the sessions and even at that time, the frequency meter Polar RS800CX has been installed for
      reading RRi during and post-session, totaling 24 hours of Heart Rate Variability (HRV)
      measurements.

      Each participant performed four sessions: CONT, ER 40% 1RM and ER 80% 1RM, and the RE
      sessions at different intensities randomized by blocks, in food standardization and
      abstention from other types of exercise, but free living conditions while using SMCG polar
      and frequency meter. In each session glycemic and autonomic responses were analyzed by a
      24-hour period started at each session.

      All sessions lasted 60 minutes, consisting of 20 minutes of a pre-intervention period (rest)
      and control session 40min (day1) and session RE (day 2), and were performed at the same time
      of day between 8:00 and 9:00. During all sessions the participants were already under the
      glucose monitoring and VFC. At the end of each session, participants were released to daily
      routine always under the use of SMCG and frequency meter.

      The experimental sessions were distributed in two weeks, being held on the 1st of each week a
      control session and on day 2 an RE session (40% 1RM and 80% 1RM). On day 3 no intervention
      was only observed for a period of 11h monitoring, the possible duration of the ER effect in
      the preceding day.

      Pre-intervention: Before any intervention, the participants remained seated in the laboratory
      for a period of 20 minutes in a quiet room without interference from noise and temperature
      between 23-24ºC (SOUZA et al, 2013.). During this period, every 5 minutes, the concentrations
      of glucose through the SMCG and RRi through the frequency meter were obtained.

      Intervention: The intensities of RE have been established based on the classification of the
      American College Sport Medicine and American Diabetes Association for individuals with DM-2,
      and categorized the low intensity with 40% 1RM and high intensity exercise with 80% 1RM
      (Colberg et al., 2010). RE sessions 40% and 80% 1RM addition control section (no RE) lasted
      40 minutes each. For RE sessions it was held three circuits with 7 exercise each, in the same
      sequence the 1RM test (the machine bench press, leg extension Chair, Flying, flexor chair,
      high Pull ahead, leg press, seated row). For RE session at 40% 1RM were performed 16
      repetitions of each exercise with an interval of 60 seconds between them and 120 seconds
      between circuits. For RE session at 80% 1RM were performed 08 repetitions of each exercise
      with an interval of 90 seconds between them and 120 seconds between circuits. The duration
      repeat the exercise both 40% and 80% 1RM was 3 seconds, 1 second in the concentric phase and
      2 seconds in the eccentric phase of the movement. In CONT sessions participants remained
      seated in a comfortable chair, being in the same room of the ER sessions.

      Post-intervention: At the end of each session the participants were released to daily
      routine, being oriented to record daily food intake (day 1) and equalize the same consumption
      in the following days (days 2 and 3) during the two weeks of intervention. Also, avoid
      performing exercises of any nature and make use of the medication in the same way in periods
      of intervention.

      Data were expressed as mean ± SD (standard deviation). Data normality was confirmed by the
      Shapiro-Wilk test. The glucose values were used to determine the average concentration of
      glucose and the prevalence of hyperglycemia (blood glucose concentrations exceeded 160
      mg.dL-1) both in 24 and in the postprandial different times: breakfast (08: 00 - 12: 00),
      lunch (13:00h - 18:00h), dinner (19:00h - 23:00h) and sleep (23:00h - 06:00h). Analysis of
      variance one way (ANOVA) with repeated measures was performed to determine differences in
      experimental conditions (CONT x 40% x 80% 1RM). Post-hoc Tukey's pair for identification of
      differences was used as an 'F' mean was obtained. Pearson's linear correlation test was also
      adopted to investigate the association between glucose and HRV. Significance was set at p
      confidence level <0.05. All statistical calculations were performed using the STATISTICA
      software for Windows v. 6.0 (StatSoft, Inc.)
    

Intervention name(s): Resistance Exercise
Intervention type(s): Other
Intervention description(s): Control Session
Resistance exercise at different intensities (40%1RM or 80%1RM)
Duration of effect
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Participant)
Keywords: Resistance Exercise; Diabetes Mellitus; Heart Rate Variability