This study documents the activities of 635 porters transporting goods along three traditional trade routes of eastern Nepal. Nearly 95% of the porters were male. They ranged in age from 10-65 years, and most of them had begun to perform long-distance portage at 12-15 years of age. Mean body mass and height of adult males in the combined sample (n β«Χ‘β¬ 438) was 49.7 Β± 5.0 kg and 155.5 Β± 6.5 cm, respectively. Adult males age 20-49 years carried loads of 73 Β± 15 kg, equivalent to 146% Β± 30% of body mass. Body size of adult males was not a strong predictor of load weight. The correlation between body mass and load was r β«Χ‘β¬ 0.24 (P < 0.0001), and between height and load was r β«Χ‘β¬ 0.16 (P < 0.001). Another significant determinant of load weight was whether the load was carried for profit or for domestic use. The most reasonable explanation for the ability of Nepali porters to carry such large loads in spite of their small body size is the ability to pace themselves by making frequent rest stops. Heart rate monitoring of 26 adult male commercial porters demonstrated how porters regulate heart rate and energy expenditure by resting the load every two to three minutes on the T-headed walking stick (tokma) and by setting the load periodically on load-resting platforms (chautaras) for longer recovery periods. Am.