The European common lizard Lacerta vivipara, a reptile of cold-temperate cl
imates, provides us an interesting model of low-temperature adaptation. Ind
eed its unique cold-hardiness strategy, which employs both freeze tolerance
and freeze avoidance, may be seen as the primary reason for its large dist
ribution, which extends from Spain to beyond the Arctic circle. To study th
e metabolism supporting this capacity, we used three techniques: two techni
ques of calorimetry (oxygen consumption and thermogenesis) and nuclear magn
etic resonance spectroscopy. These techniques were used to examine the meta
bolic balance and the different molecular pathways used between three diffe
rent periods through the year (September, January, and May). The results sh
ow a significant 20% augmentation of winter anaerobic metabolism compared t
o other periods of the year. This is mainly because of an activation of the
lactic fermentation pathway leading to an increase of lactate concentratio
n (>34% in winter). Furthermore, glucose, which increases some 245% in wint
er, is used as antifreeze and metabolic substrate. Furthermore, this study
provides evidence that the physiological adaptations of the common lizard d
iffer from those of other ectotherms such as Rana sylvatica. Concentrations
of alanine and glycerol, commonly used as antifreeze by many overwintering
ectotherms, do not increase during winter.