Department of Anthropology, University of Notre Dame, South Bend, Indiana, USA.
SUNY, University at Albany, Albany, New York, USA.
Am J Hum Biol. 2020 Nov;32(6):e23432. doi: 10.1002/ajhb.23432. Epub 2020 Jun 27.
Elevated resting metabolic rates (RMR, kcal/day) are a well-established mechanism for maintaining core body temperature among cold climate populations. A high degree of interindividual variation has recently been noted among circumpolar populations. To further examine RMR variability, we investigated anthropometric and metabolic differences among reindeer herders from subarctic Finland.
Resting metabolic rates, body mass, body composition, height, age, and sex were measured among 20 reindeer herders (5 females, 15 males, 20-64 years) from seven herding districts surrounding the Arctic Circle of Finland in January of 2019.
Females had a mean RMR of 1798 ± 216 kcal/day and males 1753 ± 503 kcal/day. When controlling for body mass and fat-free mass, females had significantly higher RMRs relative to males (P < .01). Contrary to previous cold climate population studies, measured RMR among males was not significantly different from predictive equation estimates (P > .05). However, predictive equations significantly underestimated female RMR by a mean of 25.2% ± 5.9% (P < .01).
These results mirror earlier findings, though in ways previously unseen. In this population: (a) There is a high degree of RMR interindividual variability, but only among males, and (b) there is evidence for elevated RMR, but only among females. Though the sample size is small, preliminary results suggest the presence of sex-based differences in metabolic adaptations to cold climates within this population subset. Potential reasons for this sex-based difference are discussed including a presentation of a hypothesis about the dual role of thyroid hormone in both reproductive and metabolic processes.
静息代谢率（RMR，千卡/天）升高是寒冷气候人群维持核心体温的一种成熟机制。最近，人们注意到环极人群之间存在很大的个体间差异。为了进一步研究 RMR 的变异性，我们调查了来自芬兰亚北极地区的驯鹿牧民的人体测量学和代谢差异。
2019 年 1 月，在芬兰北极圈周围的七个放牧区，对 20 名驯鹿牧民（5 名女性，15 名男性，20-64 岁）进行了静息代谢率、体重、身体成分、身高、年龄和性别测量。
女性的平均 RMR 为 1798±216千卡/天，男性为 1753±503 千卡/天。当控制体重和去脂体重时，女性的 RMR 明显高于男性（P<.01）。与之前的寒冷气候人群研究相反，男性的实测 RMR 与预测方程估计值没有显著差异（P>.05）。然而，预测方程显著低估了女性 RMR，平均低估了 25.2%±5.9%（P<.01）。
这些结果反映了早期的发现，但在某些方面是以前未曾见过的。在这一人群中：（a）存在高度的 RMR 个体间变异性，但仅在男性中存在，（b）存在 RMR 升高的证据，但仅在女性中存在。尽管样本量较小，但初步结果表明，在这一人群亚组中，存在代谢适应寒冷气候的性别差异。讨论了这种性别差异的潜在原因，包括提出了甲状腺激素在生殖和代谢过程中双重作用的假说。
