Impact of ICE on Exercise Performance in the Heat
Condition: Hyperthermia
MeSH terms: Hyperthermia
Study type: Interventional

Summary: 
      The purpose of this study is to determine the effects of intermittent forearm cooling on
      exercise performance in the heat.
    

Detailed description: 
      The study will be completed in the following timeline:

      Visit 1: Baseline and VO2max testing. Visit 2-3: Trial 1 and 2

      Visit specific information is described below, however, specific data collection protocols
      for dependent variables and procedures are included below the description of the study
      design.

      Visit 1: Baseline and VO2max Testing

      Participants who are approved to participate will be scheduled for a baseline and VO2max
      testing day. Upon arrival to the lab, subjects will provide a urine sample in a clean urine
      cup. Urine specific gravity and urine color will be assessed. Nude body mass will be also be
      recorded. Privacy will be afforded for each participant while obtaining body mass measures by
      taking measurements with the participant alone in a private room behind a solid, closed door,
      and the research reading the scale outside of the room. Participants will only be permitted
      to continue to the VO2max test if the euhydrated criteria of a urine specific gravity (USG)
      <1.025 is met. If the participant arrives with a USG between 1.020 and 1.025, the subject
      will be asked to drink 500 mL of water to ensure proper hydration status. Height will be
      measured with a tape measure on Visit 1. Percent body fat will be calculated using a 3-site
      evaluation of skin fold thickness using skin fold calipers. A researcher will use appropriate
      grasping technique to measure skin fold thickness on the chest, tricep, and abdomen. This
      will take less than 5 minutes to complete. This information will be used to describe the
      subject demographics. Participants will also be asked to complete a maximal oxygen uptake
      (VO2max) test on a treadmill in a thermoneutral environment. This test will provide aerobic
      fitness levels of the participants. This visit will take approximately 1-2 hours.

      Visit 2-3: Trials 1 and 2

      Participant numbers will be randomly assigned, and trials will be ordered with a random
      number generator and assigned to a participant number. These orders will be counterbalanced
      between participants to ensure that there is not an order effect, and each participant will
      complete two trials as part of the study. Participants will be allowed to make-up trial
      visits if they are sick, suffer an injury or do not meet hydration requirements. Participants
      will be asked if they have a current illness or taking medications to determine whether they
      can complete the exercise trial. The participant's visit will be rescheduled if they have a
      fever, current illness or taking medications that influence body temperature.

      Participants will complete two trials on two separate days in a randomized counter balanced
      order:

      Trial Cooling Intervention

        1. Passive Cooling

        2. Forearm Immersion

      The exercise protocol, cooling intervention, and performance battery portions of this study
      will be conducted in a climatic chamber with ambient temperature approximately 30-40C and
      relative humidity at approximately 40-60%. Participants will drink approximately 1.4L of
      water throughout the exercise trial. Upon arrival to the lab, participants will be asked to
      indicate if they have consumed alcohol or caffeine in the last 24 hours and 12 hours,
      respectively. They will not be asked to specify exactly what they have consumed, but if they
      provide a positive indication, their trial will be rescheduled for another day. Participants
      will provide a small urine sample in a clean urine cup, and a nude body mass will be
      measured. Upon arrival to the lab, hydration status will be assessed by urine specific
      gravity, nude body mass and urine color. Participants will only be permitted to continue to
      the exercise trial if the euhydrated criteria of a urine specific gravity (USG) <1.025 is
      met. If the participant arrives with a USG between 1.020 and 1.025, the subject will be asked
      to drink 500 mL of water to ensure proper hydration status. Participants will be given
      instructions at the prior visit about how to obtain desired hydration status for the upcoming
      trial. Participants will insert a rectal probe and wear a heart rate monitor strap.
      Researchers will insert the esophageal probe. Additionally, participants will wear 4-site
      skin temperature sensors. Researchers will apply the skin temperature sensors with medical
      tape to the participants' chest, upper arm, thigh, and calf.

      Participants will enter the environmental chamber and sit for 10 minutes to become
      equilibrated. Participants will wear a metabolic mask during this time to assess baseline
      metabolic heat production. The environmental chamber will be set to 35C ambient temperature,
      50% relative humidity. After baseline measures of heart rate, rectal temperature, and
      metabolic heat production, participants will complete the perceptual indices. Participants
      will also complete an environmental symptoms questionnaire (ESQ).

      The trial will consist of three, 20-minute exercise bouts consisting of walking, running, and
      sprinting at varying speeds ranging approximately 20-90% of their VO2max. Followed by a
      12-minute "half-time" consisting of passive rest. Participants will then complete three more
      20-minute exercise bouts consisting of walking, running, and sprinting at varying speeds
      ranging approximately 20-90% of their VO2max, for a total of six 20-minute bouts.

      Each 20-minute exercise bout with be followed by a 3-minute break where cooling will occur.
      Participants will be allowed to drink 750mL of water throughout each exercise half for a
      total of 1.4L. The participant will be cooled for approximately 3 minutes after each
      20-minute exercise bout with their assigned cooling modality. Rectal temperature, esophageal
      temperature, skin temperature, heart rate, perceptual measures, and metabolic heat production
      will be collected at various time points before, during, and after exercise and cooling.
      Following the completion of the six 20-minute exercise bouts, participants will perform the
      performance battery. The performance battery will consist of an agility test, grip strength
      test, broad-jump test, sprint test, and 1-mile time trial test.

      Passive Cooling: Participants will be asked to sit in a chair in the climate chamber for
      passive cooling.

      Forearm immersion: The participant will place both of their forearms in approximately 15C
      water during forearm immersion.

      Each trial will be approximately 3 hours.

      All devices will be properly cleaned according to manufacturer's instruction prior to use by
      other participants.
    

Intervention name(s): Forearm cooling
Intervention type(s): Device
Intervention description(s): forearm cooling will be performed for active cooling assessment.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Participants receive two cooling treatments on separate study visits: 1) passive cooling 2) forearm immersion cooling
Masking: None (Open Label)
Primary purpose: Treatment