Research design.

<p>BS – blood samples, T_re – rectal temperature, T_mu – muscle temperature, T_sk – skin temperature. Cognitive function (CF) testing involved the unpredictable task switching test (executive function), the forward digit-span task test (short term memory), and the forced-choice recognition memory test (short term spatial recognition). Neuromuscular (NM) testing involved evaluation of spinal (H-reflexes, M-waves) and supraspinal (V-waves) excitability, evaluation of muscle contractility characteristics induced by a 1-s electrical stimulation at 1 Hz, 20 Hz, 100 Hz and TT-100 Hz; evaluation of maximal voluntary contraction torque and central activation of exercising muscle was performed with a TT-100 Hz superimposed stimulation on the maximal voluntary contraction. Intermittent head-out immersion in bath water at 14°C continued until the rectal temperature decreased to 35.5°C or until 170 min total (120 min maximum total immersion time), at which time the immersion ended regardless of the rectal temperature.</p

VO₂, metabolic heat production and metabolic shivering before and during body cooling.

<p>*P<0.05, compared with before;</p>#<p>P<0.05 between fast cooling (FC) and slow cooling (SC) groups. Values are means ± SD.</p><p>VO₂, metabolic heat production and metabolic shivering before and during body cooling.</p

Spinal reflex excitability before and after body cooling.

<p>*P<0.05, compared with before. Fast cooling group (FC); Slow cooling group (SC). Values are means ± SD.</p><p>Spinal reflex excitability before and after body cooling.</p

The blood variables before and after body cooling.

<p>*P<0.05, compared with before;</p>#<p>P<0.05, between fast cooling (FC) and slow cooling (SC) groups. Values are means ± SD.</p><p>The blood variables before and after body cooling.</p

Subjective sensation rating (in points) during passive body cooling.

<p>n.s. P>0.05, non-significant between fast cooling (FC) and slow cooling (SC) groups. Values are means ± SD.</p><p>Subjective sensation rating (in points) during passive body cooling.</p

Changes in supraspinal (V-wave) response before and after body cooling.

<p>* P<0.05, compared with before. Fast cooling group (FC); Slow cooling group (SC).Values are means ± SD.</p

Body temperatures before and after body cooling.

<p>*P<0.05, compared with before;</p>#<p>P<0.05 between fast cooling (FC) and slow cooling (SC) groups. T_re – rectal temperature, T_mu – muscle temperature, T_sk – skin temperature. Values are means ± SD.</p><p>Body temperatures before and after body cooling.</p

Voluntary and electrically induced skeletal muscle properties before and after cooling.

<p>*P<0.05, compared with before; MVC – maximal voluntary contraction, CAR – central activation ratio; P1, P20, P100 – 1 Hz, 20 Hz, 100 Hz electrical stimulus, respectively; P1/P100 – 1/100 Hz ratio; HRT – Half-relaxation time. Fast cooling group (FC); Slow cooling group (SC). Values are means ± SD.</p><p>Voluntary and electrically induced skeletal muscle properties before and after cooling.</p