What pack weight can you carry?

Just as important as how to carry a load is how much load can you carry. Some might say it is even more important, and certainly how you carry a load may limit how much you can carry.

Just as important as how to carry a load is how much load can you carry. Some might say it is even more important, and certainly how you carry a load may limit how much you can carry.

One of my mountaineering books tells a story of hut building on the border between Switzerland and Italy. Guides from both sides were involved, and competition was natural. One Swiss guy was reputed to be extrordinarily strong, able to carry huge loads up the mountain. And so the Italians watched with great interest as he shouldered the cast iron stove for the new hut and started up. Some way up it became clear that he was struggling a bit, and one Italian was moved to offer some sympathy over the weight of the stove. Sympathy, or maybe a delicate needle? The Swiss guide replied that the stove was no problem, but the full sack of flour inside it was a bit heavy! [If anyone knows the book and page for this story, please remind me!] But while there are plenty of good stories, let's be realistic and remember that this is bushwalking, and we are doing it for fun. You should not be carrying a huge load which makes you lose all sense of enjoyment in the outing. So what loads can be carried reasonably? The following couple of paraphrased quotes cover some actual Army research and experiences - although the author also bemoans the fact that the Army (any Army!) tends to ignore all this reasearch in practice.

One of the studies was conducted by Institute William Frederick in Germany in the last few years of the 19th Century. The Institute was particularly interested in measuring the effect on infantrymen who were carrying different loads under varying conditions of temperature. The research demonstrated that in cool weather a load of forty-eight pounds could be carried on a fifteen mile march by acclimatized soldiers that were in good physical condition. However, in warm weather the same load produced an impairment of physical strength, and the soldiers did not return to a normal state until some time during the next day following the march. The Germans then increased the weight of the load to sixty-nine pounds and discovered that even during cool weather the soldiers in the experiment had obvious physical distress. During this phase of the study the Institute attempted to determine if physical conditioning with the same amount of weight would make a difference in the individual's reaction. The results were very interesting, demonstrating that he continued to show physical distress in an equal amount regardless of the degree of physical conditioning. ""The conclusion was therefore drawn that it is impossible to condition the average soldier to marching with this much weight no matter how much training he is given."" [48 lb is about 30% of a typical soldier weight of 160 lb.] 
The Germans subsequently determined after experimenting with varying weight amounts on forced marches that the absolute limit under the pressure and fatigue of combat was forty-eight pounds per man.

The commission pursuing the research for the British Army expended most of its effort in determining physical ailments resulting from the infantryman being heavily burdened on long marches. In general it discovered that armies in the past had on the average issued the soldier between fifty-five and sixty pounds, and by means of training marches tried to condition him. The commission finally reached the conclusion that...""not in excess of forty to forty-five pounds was a tolerable load for an average-sized man on a road march. More specifically, it stated that on the march, for training purposes, the optimum load, including clothing and personal belongings, is one-third of body weight. Above that figure the cost of carrying the load rises disproportionately to the actual increment of weight.""

The USAIS proceeded with its research based on the following data. Firstly, studies indicated that the fiftieth percentile soldier weighed 160 pounds. Secondly, field tests demonstrated that the ideal soldier's load was thirty percent of his body weight, or forty-eight pounds, and that the maximum load a soldier could carry should not exceed forty-five percent of his body weight, or seventy-two pounds.

So a figure of 30% of body weight seems to be what a soldier can carry and remain functional. I agree with that figure for soldiers, but I would point out that 'soldiers' are young, strong and under orders. They are not meant to be enjoying themselves. For the rest of us, I suggest 25% of body weight is a reasonable upper limit. I weigh 64 kg, and 25% of that is 16 kg. I find that loads under this do not affect me very much, but over that I have to put my head down and slog. If you are female and lighter, take note! You should look to limiting your load to even less than 25% if you want to enjoy the bushwalk. Dare I suggest that this is an opportunity for the males of the party to prove their machismo, by helping?