The cold-induced vasodilatation (CIVD) response was studied on 17 lowlanders (20-30 years) at Delhi, using a water bath maintained at 4 degrees+/-0.2 degreesC. The temperatures were measured at the tip of the index finger, centre of the palm, over a prominent wrist vein, and orally. Then the subjects were air-lifted to an altitude of 3500 m, where the measurements were repeated at weekly intervals for a period of 3 weeks. After this, they were flown back and retested. For comparison, the study at altitude was done on 10 acclimatised lowlanders and on 10 high-altitude natives. The peripheral blood flow under a local cold stress was calculated. Three types of CIVD responses--viz. typical hunting, proportional control, and continuous rewarmin--were observed. At altitude, the pattern was more or less the same but there was a significant reduction in the response. The responses of the natives were more or less identical to those of the lowlanders at sea level, and responses of the acclimatized lowlanders were better than the fresh inductees, but much less than the natives. The changes in peripheral blood flow was in accordance with the CIVD response.
"In this context, current results in combination with those from the previous studies (Launay et al., 2006; Amon et al., 2012; Keramidas et al., 2014c) might suggest that the attainment of positive acclimation enhancing local cold tolerance may require a longer period of hypoxic exposure. Of interest in this regard is also the report by Mathew et al., (1977) that the finger temperature during local cooling was lower after 1 week at high altitude than at sea-level, reached its nadir after 2 weeks, partially recovered after 3 weeks, and further increased after a 1-year sojourn at altitude. Still, such a time-response relationship remains hypothetical, and needs to be addressed in future studies. "
[Show abstract][Hide abstract] ABSTRACT: The study examined the effects of two short-term, intermittent hypoxic training protocols, namely exercising in hypoxia and living in normoxia (LL-TH; n = 8), and exercising in normoxia preceded by a series of brief intermittent hypoxic exposures at rest (IHE+NOR; n = 8), on the finger temperature response during a sea-level local cold test. In addition, a normoxic group was assigned as a control group (NOR; n = 8). All groups trained on a cycle-ergometer 1h⋅day-1, 5 d⋅week-1 for 4 weeks at 50% of peak power output. Pre, post, and 11 days after the last training session, subjects immersed their right hand for 30 min in 8°C water. In the NOR group, the average finger temperature was higher in the post (+2.1°C) and 11-day after (+2.6°C) tests than in the pre-test (P ≤ 0.001). Conversely, the fingers were significantly colder immediately after both hypoxic protocols (LL-TH: -1.1°C, IHE+NOR: -1.8°C; P = 0.01). The temperature responses returned to the pre-training level 11 days after the hypoxic interventions. Ergo, present findings suggest that short-term intermittent hypoxic training impairs sea-level local cold tolerance; yet, the hypoxic-induced adverse responses seem to be reversible within a period of 11 days.
High Altitude Medicine & Biology 06/2015; 16(3). DOI:10.1089/ham.2015.0013 · 1.28 Impact Factor
"Exposure to high altitude is commonly considered a predisposing environmental factor for local cold injury (Harirchi et al., 2005).Yet, the findings derived from crosssectional studies examining the peripheral vasomotor responses to local cooling, assumed to reflect risk of local cold injury, during and after prolonged hypoxia are equivocal ; a few studies have observed an enhancement of local cold tolerance (Nair et al., 1973; Mathew et al., 1977; Rai et al., 1978; Felicijan et al., 2008; Amon et al., 2012), while others have reported either an impairment (Nair et al., 1973; Savourey et al., 1997; Purkayastha et al., 1999; Castellani et al., 2002) or no change (Nair et al., 1973; Mathew et al., 1977; Daanen & van Ruiten, 2000). At high altitude, hypoxia coexists with other environmental and behavioral stressors, mainly cold and exercise, which, independently or synergistically, determine the nature and the level of acclimatization to the environment. "
[Show abstract][Hide abstract] ABSTRACT: The study examined the effects of a 10-day normobaric hypoxic confinement (FiO2: 0.14), with (HT; n = 8) or without (HA; n = 6) exercise, on the hand-temperature responses during and after local cold stress. Before and after the confinement, subjects immersed their right hand for 30 min in 8°C water (CWI), followed by a 15-min spontaneous rewarming (RW), while breathing either room air (AIR), or a hypoxic gas mixture (HYPO). The hand-temperature responses were monitored with thermocouples and infrared-thermography. The confinement did not influence the hand-temperature responses of the HA group during the AIR and HYPO CWI and the HYPO RW phases; but it impaired the AIR RW response (-1.3°C; P = 0.05). After the confinement, the hand-temperature responses were unaltered in the HT group throughout the AIR trial. However, the average hand-temperature was increased during the HYPO CWI (+0.5°C; P ≤ 0.05) and RW (+2.4°C; P ≤ 0.001) phases. Accordingly, present findings suggest that prolonged exposure to normobaric hypoxia per se does not alter the hand-temperature responses to local cooling; yet, it impairs the normoxic rewarming response. Conversely, the combined stimuli of continuous hypoxia and exercise enhance the finger cold-induced vasodilatation and hand-rewarming responses, specifically, under hypoxic conditions.
Scandinavian Journal of Medicine and Science in Sports 06/2014; 25(5). DOI:10.1111/sms.12291 · 2.90 Impact Factor
"Cold-induced peripheral vasoconstriction has been shown to significantly increase at high altitude and may increase ischemia. Thus, as a treatment, increasing oxygen pressure in tissue could inhibit ischemia, remove arterial spasm, and help endogen heat production (Dana et al., 1969; Mathew et al., 1977; Daanen and van Ruiten, 2000). Therefore, a quick descent to low altitude or an increase in barometric pressure as in a hyperbaric chamber could be a major help in treatment for frostbite. "
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