How Heavy is Too Heavy? ©

 

A picture of the author in 1981, in Algonquin Provincial Park, when I weighed a little under 100 pounds (45.5 kgs).  I was carrying a pack that tipped the scale at about 70 pounds (32 kgs), which was about 70% of my body weight.  From the Gerry L. Reynolds Collection, used with permission.

How heavy will the packs be?  How heavy should they be?  How heavy are the canoes?  How heavy is too heavy?  These were the questions that several members of Boy Scout Troop 285 asked me.  They are planning an expedition to Algonquin Provincial Park and were concerned with how heavy the packs and canoes would be and how heavy was too heavy.  I gave them the quick and simple answer that you can carry about 30% of your body weight, without becoming overly fatigued, and that if you carry more than 50% of your body weight, you would become fatigued and you would have a higher risk of injury.

After I got home, though, I got to thinking; maybe there is more to this question than I answered.  So, I did some research and here is what I found out.

 

A picture of the author in 1981, in Algonquin Provincial Park, carrying a 17-foot Coleman Ramflex canoe, which weighed 85 lbs. (approximately 39 kgs), this canoe was over 80% of my body weight.  From the Gerry L. Reynolds Collection, used with permission.

 What Determines How Much You Can Carry?

There are two key factors which determine how much you can carry, your body weight and your level of physical conditioning.  There is a direct relationship between body weight and someone’s load carrying ability: the larger the person, the greater their fit-body weight, the more they can carry.  Also, in general, the better shape you are in, the more you can carry.

How Much Can You Carry?

According to Major Townsend’s thesis, The Factor Of Soldier’s Load, you can carry up to 30% of your body weight, or for an average American male¹, about 48 to 52 pounds (22 to 24 kgs) without becoming fatigued.  For every additional 10 pounds (4.5 kgs) that you carry, above 30% of your body weight, you will become increasingly fatigued and experience, approximately, a 15% decrease in your agility, strength, speed, reaction time and endurance².  Fatigue is the result of exercise or exertion and to recover from fatigue you will need to rest.  The greater the exertion, the greater your level of fatigue and the more rest you will require.

If the load that you are carrying is greater than 45% of your body weight, which for the average American male is a weight of between 72 to 78 pounds (33 to 35 kgs), then you will become fatigued.  Additionally, you will lose more than 35% of your agility, strength, speed, reaction time and endurance and you will be a greater risk of injuring yourself when carrying these loads³.

You can carry loads of up to 59% to 94% of your body weight, which for the average American male is between 100 to 150 pounds (45.5 to 68 kgs), for short distances of 12-1/2 miles (20 kilometers) a day for several days. However, you will be significantly fatigued, and you will lose between 75% to 100% of your agility, strength, speed, reaction time and endurance.  In addition, you will be at a significantly greater risk of being injured while carrying loads of this weight⁴.

 

A picture of the author in July 17, 2017, on the Kioshkowi Lake to Little Mink Lake portage, carrying canoe, which weighed 72 lbs. (approximately 33 kgs), this is about 40% of my body weight, used with permission.

Things to Keep in Mind...

First. when the researchers talk about body weight, they mean “fit-body weight”.  If you are carrying a few too many pounds, these pounds will count against the total weight, that you can carry on your back. 

Second, this information was created from data gathered by researchers from route marches, marches that lasted from several hours to a day in length and covered up to 12-1/2 miles (20 kilometers) per march.  This is an important thing for people to keep in mind, there is a difference between portaging between lakes and hiking all day long: “long-carries” versus “short-carries”.  From personal experience, carries of less than an hour, are quickly recovered from, even if you are carrying above 30% of your body weight.  However, having said that, multiple small-carries, i.e. portages, have a cumulative effect over the course of a day and will cause you to become increasing fatigued.

 

Excerpts from Foot Marches, FM 21-18, p. 5-5

Third, “load training” can only increase a person’s ability to carry weight by 10% to 20% over the maximum that they could carry before the training began.  In other words, you can learn to carry, based on the weight of the average American male, an additional 16 to 34 pounds (7 to 15 kgs) without becoming fatigued.  Beyond this point, the researchers state, no other increases in load carrying without increasing fatigue are possible.  Additionally, the American military historian and researcher, S. L. A. Marshall advocated “load training” only up to 30% of your body weight or slightly higher.  Other researchers have found that aerobic activity, such as running, calisthenics and weight-lifting exercises are not good training for “load carrying”⁵.  Instead, it was found that the best way to train to carry weight on your back, was walking while carrying weight on your back.

 

A picture of the author in July 17, 2017, on the Kioshkowi Lake to Little Mink Lake portage, used with permission.

For more information about how to carry loads over a portage see “Algonquin Portaging 101 ©”, found HERE.

I hope that you continue to enjoy The Woodsman’s Journal Online and look for me on YouTube at Bandanaman Productions for other related videos, HERE.  Don’t forget to follow me on both The Woodsman’s Journal Online and subscribe to BandanaMan Productions on YouTube, and if you have questions, as always, feel free to leave a comment on either site.  I announce new articles on Facebook at Eric Reynolds, on Instagram at bandanamanaproductions, and on VK at Eric Reynolds, so watch for me.

That is all for now, and as always, until next time, Happy Trails!

Notes

¹ Townsend, Stephen J., Major; The Factors Of Soldier's Load, p. 15

Major Townsend wrote an excellent thesis, which I highly recommend reading: it is a summary of several military field manuals and research reports.  According to Major Townsend, average American males weigh between 160 to 171 pounds or 73 to 78 kgs.

² Ibid, p. 15

³ Ibid, p. 16

⁴ Ibid, p. 16

⁵ Ibid, p. 81-82

Sources

Townsend, Stephen J., Major; The Factors Of Soldier's Load, [Fort Leavenworth, Kansas, 1994], p. 15-16, http://www.themilsimperspective.com/wp-content/uploads/2018/10/a284389-THE-FACTORS-OF-SOLDIERS-LOAD.pdf, accessed 02/02/2020

Foot Marches, FM 21-18 [Headquarters, Department of the Army, Washington, DC, June 1990], p. 2-7

The Infantry Rifle Company, FM 3-21.10 (FM 7-10) [Headquarters, Department of the Army, Washington, DC, July 2006], p. 11-4, https://www.bits.de/NRANEU/others/amd-us-archive/FM3-21-10%2806%29.PDF, accessed 2/3/2020