However, a marked difference in sweating output is observed between skiers and swimmers, despite similar VO 2 max skiers vs. Distance runners can lose large amounts of body fluid under certain conditions. The primary adaptive change in distance runners may be improved sweating and evaporative efficiency, leading to a reduction in body heat storage and physiological strain. Due to their improved thermoregulatory responses, physically trained individuals are more capable of withstanding higher intensity exercise in hotter conditions than their untrained counterparts.
However, according to Midgley et al. Therefore, the aim of this study was to compare the peripheral sweating responses between male long-distance runners and sedentary counterparts and to evaluate the correlation between sweating responses and VO 2 max. Following approval of experimental protocols from the research committee at the University of Soonchunhyang and obtaining written informed consent, normotensive volunteers were enrolled in the study.
All procedures complied with the Declaration of Helsinki. The subjects were 36 healthy male volunteers from the University of Soonchunhyang and Korea National Sports University and included 20 sedentary controls subjects who did not perform regular physical activity for the previous 3 years, self-reported and 16 5—10 km long-distance runners who had 7—12 years of athletic training average 9.
General physical characteristics of the subjects are summarized in Table 1. The trained runners had significantly lower percent fat and body mass index and a higher VO 2 max than those of the controls. No differences in age, height, weight, or body surface area were observed between the groups. Each subject returned written informed consent to participate in the study, after being thoroughly acquainted with the purpose and the experimental procedures, as well as any potential risks.
Subjects were instructed to refrain from alcohol consumption or smoking 24 hours before the test. The volunteers also refrained from medications during the testing period. All experiments were performed at 2—5 p. Recent developments have resulted in the commercial availability of extremely sensitive and reliable sudorometers, which can conveniently analyze and display sweat rates and volumes [16].
The quantitative sudomotor axon reflex test QSART is a useful method for evaluating postganglionic sympathetic C fiber function. Iontophoresed acetylcholine ACh evokes a measurable and reliable sweat response that has been used to measure autonomic responses [17].
The capsule consists of three concentric compartments. ACh is placed in the outer compartment and directly stimulates the underlying muscarinic receptors of the sweat gland cells DIR sweating.
Additionally, ACh produces axon reflex sweating Figure 1 [20]. Directly activated and axon-reflex-mediated sweating is shown. Axon reflex-mediated sweating during 0—5 min iontophoresis AXR1 sweating.
Axon reflex-mediated sweating during 6—11 min post-iontophoresis AXR2 sweating and directly activated sweating during 6—11 min post-iontophoresis DIR sweating are shown. Upon arrival at the climate chamber, each subject changed into light clothing and rested quietly for 1 hour.
Capsule 1 was placed midway between the wrist and elbow joints, whereas Capsule 2 was placed 10 cm proximal to Capsule 1. Immediately following current loading, the capsules were detached and the underlying skin was wiped. The capsules were then swapped. ACh-induced sweat output followed a typical time course Figure 1. The time lapse before onset of the AXR1 sweat response was measured as a response latency in minutes Figure 1. Sweat rate was measured according to the capacitance hygrometer-ventilated capsule method [18] , [20].
The change in relative humidity of the effluent gas was detected by a hygrometer H, Technol Seven, Yokohama, Japan. These measurements were performed while the participants rested quietly in a chair. At the end of the QSART recording, the number of activated sweat glands was determined according to the iodine-impregnated paper method [20] , [23]. ACh solution was applied to the forearm skin surface near Capsule 2 to directly stimulate the underlying sweat glands and was wiped off.
Iodine-starch paper was then pressed against the surface area. The number of blue-black pigment spots in an area of 0. Therefore, cycling was selected as the mode of exercise for this investigation to minimize any advantage distance runners might already have due to the continuous aerobic nature of the work out. Physical load was increased gradually until the subject became exhausted. The sweating responses and various temperatures were compared using the paired and independent t -test to compare within and between groups.
VO 2 max was significantly higher in trained subjects than that in controls Pre- and post-test oral temperatures tended to be lower in the trained subjects than in the controls pre, However, no significant difference was observed. Pre- and post-test skin temperature was significantly higher in trained subjects than in controls pre, Sweat onset time for AXR1 was 0.
Trained subjects demonstrated higher values of AXR1 2. Activated sweat glands and sweat output per gland were also higher in trained subjects than in the controls VO 2 max was not related to activated sweating, sweat onset time, sweat output per gland or activated sweat glands in the controls. Thus, the sweat response of individuals in the control group had a lower correlation with aerobic capacity. AXR, axon reflex-mediated sweating during measurement 0—5 min. AXR, axon reflex-mediated sweating.
The main finding of this study was that long-distance runners have greater capacity for peripheral heat dissipation. A significant and strong correlation was found between VO 2 max and DIR sweating in the trained subjects but not in the controls. Figure 3a and 3b show the significant correlation between VO 2 max and the AXR response induced by iontophoretic ACh, which was greater in the trained subjects than in the controls.
Cutaneous application of iontophoretic ACh induces vasodilatation [25]. An increased skin vasodilatory response is associated with increased skin temperature [26] , which in turn synchronizes sweat expulsion [27] , [28] , [29]. Conversely, a decrease skin temperature is associated with decreased sweat rates [30]. Long-term heat acclimation has been shown to shorten sweat onset time, in contrast to short-term heat acclimation, which is not known to induce this change [31].
The trained subjects had shorter AXR1 sweat onset time. These results are in agreement with the study by Baum et al. Another possibility is that your thyroid is releasing more hormones to help fuel your increase in activity, and night sweats are a side-effect. Change your sleepwear: you may want to switch to something made of a moisture-wicking material for your sleepwear, sheets, blankets and pillows.
Run and eat earlier: we hate to break it to all the night runners out there, but if you tend to run late in the evening, and subsequently eat late as well, you may have to run earlier in the day to avoid night sweats.
Try a magnesium supplement: studies have shown that a magnesium supplement is effective at reducing hot flashes for women experiencing menopause, and it can help reduce night sweats in runners, too.
Magnesium comes with other benefits as well, such as helping to regulate muscle and nerve function goodbye, muscle cramps! If you choose to take a supplement, talk to your doctor first. Existing subscribers, please log in with your email address to link your account access. Paid quarterly.
Inclusive of applicable taxes VAT. Paid quarterly Inclusive of applicable taxes VAT.
0コメント