Metabolic Thresholds and Fat Utilization Points Correlation
Condition: Exercise Physiology
Study type: Observational

Summary: 
      To examine existence of connection between fat utilization points, both maximal and minimal
      with individual metabolic thresholds in different subjects. As a consequence, this innovative
      approach could offer a supplementary method for both aerobic and anaerobic thresholds
      detection as well as useful and practical exercise intensity selection marker.
    

Detailed description: 
      This study aims to examine the existence of connection between metabolic thresholds and fat
      oxidation points in diverse group of subjects. From the physiological perspective, during
      exercise with increasing intensity, three phases of the body's energy utilization and two
      threshold points can be defined. These threshold points have been named metabolic thresholds
      and as such are considered as indicators of exercise capacities. Several authors have
      suggested, that the first threshold should be called the 'aerobic threshold' (AeT) and the
      second the 'anaerobic threshold' (AnT). The energy contribution from fat oxidation increases
      during low-to-moderate exercise intensities and then markedly declines when the intensity
      becomes high, at which point carbohydrates (CHO) remain the dominant energy substrate. A term
      used to describe exercise intensity where fat oxidation reaches optimum, is maximal fat
      oxidation point (FATmax) whereas exercise intensity matching the negligible fat oxidation is
      labelled FATmin. During physical activity, due to limited availability of CHO, subjects are
      more dependent on energy originating from fat when aiming to optimize endurance performance,
      body composition, optimize weight control and the metabolic rate. Exercise at the intensity
      eliciting FATmax revealed best results in treatment and prevention of obesity-associated
      conditions, cardio-vascular and pulmonary diseases by means of increase in maximal fat
      oxidation rates (MFO), insulin sensitivity, improvements in ventilator efficiency and cardiac
      output, demonstrating a significant role in the treatment of these impairments. As a
      follow-up, studies demonstrated how the lowest beneficial effect was observed when exercise
      was performed above intensity matching negligible fat oxidation rate (FATmin), contributing
      to diminished protection of exercise therapy. In consequence, increased cardio-metabolic
      demands of exercise performed above FATmin also have a higher impact on mortality rates in
      comparison to low-moderate aerobic exercise. Therefore, choosing appropriate exercise
      intensity may play a decisive role in decreasing risk factors accompanying obesity-associated
      conditions.

      Investigators aim to determine metabolic thresholds and fat oxidation points by using
      non-invasive breath-by-breath gas analysis during either treadmill or cycle ergometry.
      Metabolic thresholds will be detected by using gas analysis, via ventilatory parameters. Fat
      oxidation points will be determined using indirect calorimetry.

      Participants will perform graded ergometry test (2min stages and 1km/h or 50 W load
      increase), on either cycle or treadmill ergometer, till exhaustion to determine maximal
      oxygen uptake (VO2max), with gases being collected at the mouth level by using
      spiroergometry.

      The strength of the relationship between intensities matching VO2 at AeT and VO2 at FATmax
      will be assessed using the Pearson product moment (r) correlation coefficient with same being
      done for AnT and FATmin correlation. A coefficient of determination (R2) will be used to
      detect the proportion of existing variance. A paired t-test will be used to asses'
      differences between measured variables.

      Associated heart rate at the AeT/FATmax and AnT/FATmin will be used as training mean to
      identify proper training intensity.

      The time frame of the study is about 3 years, depending on the availability of the subjects.
      Planed study begin is early 2016. Participants will be every day clients of the Institution
      and will be recruited on a voluntary basis as they arrive to the testing facilities through
      this 3 years period.Through this 3 years period, statistical analysis of the collected data
      for each group of subjects will be performed and observations will be published. Up to 7
      publications are expected to result from this research.
    

Intervention name(s): Metabolic thresholds and fat oxidation points relationship
Intervention type(s): Diagnostic Test
Intervention description(s): Investigators aim to determine exercise intensity at which metabolic thresholds and fat oxidation points occur by using non-invasive breath-by-breath gas analysis during either graded treadmill or cycle ergometry test (2min stages and 1km/h or 50 W load increase) till exhaustion to determine maximal oxygen uptake (VO2max), with gases being collected at the mouth level. The strength of the relationship between AeT and at FATmax will be assessed using the Pearson product moment (r) correlation coefficient with same being done for AnT and FATmin correlation. A coefficient of determination (R2) will be used to detect the proportion of existing variance. A paired t-test will be used to asses' differences between measured variables. Bland-altman will be used to determine levels of agreement.
Observational model: Case-Only
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Athletic, moderately trained, sedentary and obese males and females
      
Keywords: Exercise; Metabolic thresholds; Fat oxidation