The carrying of a load of 44 pounds is done at the same expenditure of energy as the carrying of one's own body weight when the rate is three miles an hour, so the soldier's equipment would call for the added expenditure of 48 calories (44 × 1.1), making his total hourly expenditure of energy nearly 300 calories (249 + 44) during a hike on a level road. His daily requirement for energy might be:
| Calories | |
|---|---|
| Sleeping 8 hours at 70 calories per hour | 560 |
| Resting in camp 6 hours at 77 calories per hour | 462 |
| Hike of 30 miles, 10 hours at 300 calories per hour | 3000 |
| 4022 |
This would be the heat production of a soldier on a day of a "forced march." The ordinary day's march is only fifteen miles.
This assumes a level road. If, however, there are hills to climb and the body weight and the pack are lifted 1000 feet during the hike, this is done at the additional expense of approximately 0.96 calory of energy per pound of weight lifted. If the man weighed 156 pounds and the pack 44 pounds, the additional fuel requirement would be 192 calories (200 × 0.96). The total energy requirement for this kind of a hike would have been 4200 calories. Walking down hill is accomplished at an expenditure of slightly less energy than walking on the level, but this factor need not concern one.
Supposing, however, this individual were running, lightly clad, on a level road in a race for a distance of 40 miles at the rate of 5.3 miles per hour, he would complete the distance in seven hours and thirty-three minutes, which is a reasonable record. His metabolism might thus be calculated:
| Calories | |
|---|---|
| Sleeping 10 hours at 70 calories per hour | 700 |
| Resting 6 hours, 23 minutes, at 77 calories per hour | 497 |
| Running 7 hours, 33 minutes, at 561 calories per hour | 4236 |
| 5433 |
It is a matter of record that a man has run between Milwaukee and Chicago, a distance of 80 miles, in about fifteen hours. Such an amount of work would have required over 9000 calories for the day.
These calculations are all based upon experimental results obtained in various laboratories in different parts of the world and can be accepted as being free from any gross error.