Astaxanthin Reduces Exercising Heart Rate.
Condition: Metabolic Flexibility
Study type: Interventional

Summary: 
      Briefly, this study involved 2 trials: baseline (Trial 1) and post-astaxanthin intervention
      (Trial 2). Both trials included participants completing a graded exercise test while
      connected to a metabolic cart, to measure cardiorespiratory measures. Between trials,
      participants were supplemented with either 12 mg of astaxanthin or placebo for 4 weeks. It
      was hypothesized astaxanthin supplementation would increase rates of fat oxidation, while
      decreasing carbohydrate oxidation and blood lactate accumulation.
    

Detailed description: 
      METHODS

      Experimental Design

      The current study implemented a double-blind, between-subject study design with dependent
      variables examined at multiple timepoints across each trial. To best observe changes in our
      selected dependent variables, subjects reported to the laboratory on two separate occasions
      (i.e. pre-post) following 4 weeks of astaxanthin supplementation.

      Subject Approval from the Institutional Review Board was granted before recruiting subjects
      (University of North Alabama, Institutional Review Board #: 20-21-071). Each subject
      completed a Physical Activity Readiness Questionnaire, a medical questionnaire, and provided
      their written and verbal consent to voluntarily participate in the present study. Inclusion
      criteria for each subject included the following: 1) between the ages of 18-45; 2) free of
      any cardiometabolic disease medication; 3) classified as overweight with a bodyfat percent of
      ≥ 20% for males and ≥ 25% for females; 4) and not currently pregnant or actively trying to
      become pregnant. Additionally, subjects eliminated all dietary supplements at least two weeks
      prior to the start of the study. Using G-Power software and changes to bodyfat as a primary
      dependent variable, we determined a priori that 20 subjects would be sufficient to achieve a
      desired power of 0.85, using a moderate-high effect size, and an alpha level set at 0.05.
      Although 46 individuals were recruited, only 21 fit the inclusion criteria and were
      randomized into either an astaxanthin or placebo group following their first visit. Due to
      two participants withdrawing from the study as a result of health concerns not related to the
      study procedures, 19 subjects were included in statistical analysis.

      Preliminary Data During the first visit, subjects had their body composition assessed via
      bioelectrical impedance analysis as well as height, mass, and blood pressure by the same,
      trained investigator pre-post intervention. Following the collection of anthropometric data,
      subjects who met inclusion and exclusion criteria were then asked to attempt to maintain
      their current dietary habits for the duration of the intervention. Dietary intake was then
      recorded pre-post intervention via 3-day food logs which consisted of 2 weekdays and 1
      weekend day (i.e. Thursday, Friday, Saturday) to better reflect typical intakes. Subjects met
      with the primary investigator and were instructed how to complete the food logs, regarding
      quantity size and liquid amount estimations. Total energy intake, carbohydrate, protein, and
      fats were analyzed for nutrient amounts using MyFitnessPal and were then used in statistical
      analysis.

      Experimental Trials (Trials 1-2) Following the collection of preliminary data, subjects
      completed a graded exercise test on a cycle ergometer. Prior to the start of exercise,
      subjects donned a heart rate monitor, established seat height, and were then connected to a
      metabolic cart to record cardiorespiratory measures for the calculation of fat and
      carbohydrate oxidation rates. Following connection to the metabolic cart, subjects sat
      quietly for 5 min to collect resting oxidation rates ('rest'). Subjects then straddled the
      cycle ergometer and began pedaling at an initial 30 W (females) or 50 W (males) for 5 min
      (Stage 1). For each subsequent stage, resistance increased by 15 W and lasted for 5 min
      (Stages 2-5). Following completion of 5 stages (90 W total for females and 110 W total for
      males), resistance then increased by 15 W every minute, until volitional exhaustion was
      achieved and the subjects' volume of oxygen (VO2) peak was recorded. The present protocol was
      pilot tested (n = 6) prior to the initiation of the present study and determined by the
      investigative team as acceptable for non-exercising and overweight individuals to all
      complete with minimal fluctuation in heart rate (±2 bpm) during the last min of each stage.

      During the last 30 s of each stage, subjects had their finger pricked (detailed further
      below) for the measurement of capillary lactate and glucose. Furthermore, heart rate and
      overall ratings of perceived exertion were recorded at the end of each stage. Due to the
      collection of oxidation rates, subjects were required to fast for 5 h and avoid alcohol
      consumption for 48 h prior to each trial. Subjects were also required to abstain from
      caffeine on the day of testing and avoid strenuous lower body exercise 48 h prior to each
      experimental trial.

      Fat and Carbohydrate Oxidation Rate Measurements All cardiorespiratory measures were averaged
      from expired gas collected by the metabolic cart. The first 240 seconds of each stage were
      excluded and the remaining 60 seconds were recorded using breath-by-breath data and averaged
      in two, 30-second cycles. Stoichiometric equations were utilized when measuring total fat and
      carbohydrate oxidation rates (g · min-1). These equations assumed protein oxidation rates
      were negligible (~5%) and therefore, were ignored.

      Fat oxidation (g ∙ min-1) = 1.67 VO2 (L ∙ min-1) - 1.67 VCO2 (L ∙ min-1) Carbohydrate
      oxidation (g ∙ min-1) = 4.55 VO2 (L ∙ min-1) - 3.21 VCO2 (L ∙ min-1)

      Lactate and Glucose Concentration Measurement At the end of each stage during the graded
      exercise test, a sample of capillary blood was collected from the subjects' finger. The
      subjects had their finger wiped with an alcohol swab and then allowed to air dry prior to a
      prick with a self-withdrawing safety lancet. The first drop of blood was wiped away and the
      second drop of blood was analyzed using a Lactate Plus Meter Blood Analyzer. Additionally,
      capillary blood glucose concentrations were analyzed using a Precision Xtra Blood Glucose
      Analyzer

      . Supplementation Schedule The supplementation intervention was scheduled following Trial 1
      and took place for 4 weeks before subjects reported back to the laboratory for Trial 2.
      Subjects were randomly assigned to supplement with either 12 mg of encapsulated astaxanthin
      (astaxanthin and sunflower oil; 6 mg per capsule) or placebo (sunflower oil only) daily in
      the form of two gel capsules. Subjects were advised to ingest one capsule in the morning and
      one capsule at night. Both the astaxanthin and placebo pills were similar in appearance (red
      and oval shaped) and size and all supplements were provided by AstaReal.
    

Intervention name(s): Astaxanthin; Placebo
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Our aim was to examine the impact astaxanthin would have, if any, on markers of metabolic flexibility in overweight individuals in comparison to a placebo.; To have adequately test the effects of astaxanthin, we provided one group a placebo matched in appearance and taste.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Treatment
Keywords: substrate oxidation; lactate; supplement