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Resilience and Survival in Extreme Environments 151

above 15,000 ft. for 4 days. When later tested in the laboratory, this man dem-

onstrated an ability to maintain an elevated metabolic rate that maintained
hand and foot temperatures (Pugh, 1963). This ability to survive by “thinking

warm thoughts” is supported by studies involving Tibetan monks (Benson,
Malhotra, Goldman, Jacobs & Hopkins, 1990). Techniques of biofeedback
have been used to treat Raynaud’s syndrome due to previous cold injury. Th is
was a special focus of studies conducted by the U.S. Army Research Institute
of Environmental Medicine (USARIEM), involving Argentinian soldiers

who suffered cold injury in the Falklands (Ahle, Buroni, Sharp & Hamlet,
1990; Jobe et al., 1985).

Specific neurotransmitters such as neuropeptide Y (NPY) also appear to
play a role in peripheral vasodilation. Benson et al. (1990) examined Buddhist
meditation techniques and observed metabolic rate increases and decreases
greater than 60% accompanied by marked changes in brain electrical activ-
ity (EEG). Th e specific neurochemical pathways involved in such phenomena

have not yet been fully characterized, but endocannabinoids appear to play

a role (Stefano et al., 2003). Cognitive and psychomotor deficits that occur
in some individuals under very high-stress conditions are clearly related to

brain NE reductions. Th ese effects can be reversed by providing the rate-lim-
iting precursor substrate, tyrosine, as a dietary supplement (Rauch & Lieber-

man, 1990; Shurtleff , Thomas, Schrot, Kowalski & Harford, 1994).
Although cold strain modeling indicates that an insulative layer of
body fat may be helpful to maintain core body temperature (Xu, Tikuisis,
Gonzalez & Giesbrecht, 2005), it does not appear to be the case that obesity
(excessive insulative body fat) improves resistance to cold. On the contrary,
physically trained individuals generally demonstrate better cardiovas-
cular response to cold, and fit individuals with less body fat compensate

with greater shivering thermogenesis (Glickman-Weiss, Goss, Robertson,
Metz & Cassinelli, 1991). In a thorough and interesting review of theory

and experimental findings reported by competing laboratories over the
course of almost 40 years, Armstrong and Pandolf (1986) conclude, “…most
authors agree that physical training in a cool environment, or a high level of
cardiorespiratory physical fitness, improves physiological responses during

exercise at high ambient temperatures and speed the process of heat acclima-
tion” (Armstrong & Pandolf, 1986, p. 223). Bittel, Nonotte-Varly, Livecchi-
Gonnot, Sovourey, and Hanniquet (1988) have shown that during exposure
to cold, aerobically fi t individuals can maintain warmer skin temperatures

than their less fit counterparts. Young et al. (1995) observed that subjects
exposed to cold after an 8-week endurance training program produced a

stronger cutaneous vasoconstrictor response to cold. While undergoing
acclimatization to any climate, it is important to maintain adequate hydra-
tion because even slight dehydration can degrade physical performance and

affect thermoregulatory response. However, very recent studies performed

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