An Ice Vest, but Not Single-Hand Cooling, Is Effective at Reducing Thermo-Physiological Strain During Exercise Recovery in the Heat

Abstract

Sports limit the length of breaks between halves or periods, placing substantial time constraints on cooling effectiveness. This study investigated the effect of active cooling during both time-limited and prolonged post-exercise recovery in the heat. Ten recreationally-active adults (VO 2peak 43.6 ± 7.5 ml·kg −1 ·min −1 ) were exposed to thermally-challenging conditions (36°C air temperature, 45% RH) while passively seated for 30 min, cycling for 60 min at 51% VO 2peak , and during a seated recovery for 60 min that was broken into two epochs: first 15 min (REC 0−15 ) and total 60 min (REC 0−60 ). Three different cooling techniques were implemented during independent recovery trials: (a) negative-pressure single hand-cooling (~17°C); (b) ice vest; and (c) non-cooling control. Change in rectal temperature ( T re ), mean skin temperature ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:msub><mml:mrow><mml:mover accent="false" class="mml-overline"><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mo accent="true">¯</mml:mo></mml:mover></mml:mrow><mml:mrow><mml:mtext>sk</mml:mtext></mml:mrow></mml:msub></mml:math> ), heart rate (HR), and thermal sensation (TS), as well as mean body temperature ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:msub><mml:mrow><mml:mover accent="false" class="mml-overline"><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mo accent="true">¯</mml:mo></mml:mover></mml:mrow><mml:mrow><mml:mtext>b</mml:mtext></mml:mrow></mml:msub></mml:math> ), and heat storage ( S ) were calculated for exercise, REC 0−15 and REC 0−60 . During REC 0−15 , HR was lowered more with the ice vest (−9 [−15 to −3] bts·min −1 , p = 0.002) and single hand-cooling (−7 [−13 to −1] bts·min −1 , p = 0.021) compared to a non-cooling control. The ice vest caused a greater change in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:msub><mml:mrow><mml:mover accent="false" class="mml-overline"><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mo accent="true">¯</mml:mo></mml:mover></mml:mrow><mml:mrow><mml:mtext>sk</mml:mtext></mml:mrow></mml:msub></mml:math> compared to no cooling (−1.07 [−2.00 to −0.13]°C, p = 0.021) and single-hand cooling (−1.07 [−2.01 to −0.14]°C, p = 0.020), as well as a greater change in S compared to no cooling (−84 [−132 to −37] W, p &amp;lt; 0.0001) and single-hand cooling (−74 [−125 to −24] W, p = 0.002). Across REC 0−60 , changes in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:msub><mml:mrow><mml:mover accent="false" class="mml-overline"><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mo accent="true">¯</mml:mo></mml:mover></mml:mrow><mml:mrow><mml:mtext>b</mml:mtext></mml:mrow></mml:msub></mml:math> (−0.38 [−0.69 to −0.07]°C, p = 0.012) and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:msub><mml:mrow><mml:mover accent="false" class="mml-overline"><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mo accent="true">¯</mml:mo></mml:mover></mml:mrow><mml:mrow><mml:mtext>sk</mml:mtext></mml:mrow></mml:msub></mml:math> (−1.62 [−2.56 to −0.68]°C, p &amp;lt; 0.0001) were greater with ice vest compared to no cooling. Furthermore, changes in in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M6"><mml:msub><mml:mrow><mml:mover accent="false" class="mml-overline"><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mo accent="true">¯</mml:mo></mml:mover></mml:mrow><mml:mrow><mml:mtext>b</mml:mtext></mml:mrow></mml:msub></mml:math> (−0.39 [−0.70 to −0.08]°C, p = 0.010) and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M7"><mml:msub><mml:mrow><mml:mover accent="false" class="mml-overline"><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mo accent="true">¯</mml:mo></mml:mover></mml:mrow><mml:mrow><mml:mtext>sk</mml:mtext></mml:mrow></mml:msub></mml:math> (−1.68 [−2.61 to −0.74]°C, p &amp;lt; 0.0001) were greater with the ice vest compared to single-hand cooling. Using an ice vest during time-limited and prolonged recovery in the heat aided in a more effective reduction in thermo-physiological strain compared to both passive cooling as well as a single-hand cooling device.

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