Why Add 26,000 Pounds of Stress Per Mile Walked?

Heavy body armor increases the amount of strain on the joints, causing fatigue and long-term medical issues.

When it comes to the load law enforcement and military operators carry, we’ve all heard the phrase, “Ounces equal pounds and pounds equal pain.” What may not seem like much of a difference when you hear that one body armor plate is a couple pounds lighter than another actually makes a huge difference to the person wearing it. Every ounce truly matters.

An article published by Harvard Medical School states the somewhat obvious: “Excess weight puts additional stress on weight-bearing joints (the knee, for example).” We may consider this when talking about the overall weight of an individual - how being overweight impacts the joints. But, do we take this into consideration when calculating the load our officers and military servicemen and women are subjected to on a daily basis?

One Extra Pound Carried Equals 4,800 Extra Pounds of Pressure

"The accumulated reduction in knee load for a 1-pound loss in weight would be more than 4,800 pounds per mile walked," says researcher Stephen P. Messier, PhD, of Wake Forest University. So, if a person was carrying 10 pounds less weight, “each knee would be subjected to 48,000 pounds less in compressive load per mile walked."

Applying this same math to the weight of body armor, the difference between a typical Level III 10”x12” ceramic body armor insert at about 6 pounds each and ShotStop’s Duritium® III+PS plate (3.3 pounds each) is roughly 5.4 pounds when carrying a front and back plate (12 lbs. - 6.6 lbs. = 5.4 lbs.). So, 5.4 pounds times 4,800 pounds per mile walked is just shy of 26,000 additional pounds of pressure per mile walked when an officer wears a pair of 6 pound ceramic plates versus a set of 3.3 pound Duritium® III+PS plates.

The Force Applied to Your Joints is 1½ to 4 Times Your Body Weight (Including Armor)

The Harvard study mentioned above states that, “When you walk across level ground, the force on your knees is the equivalent of 1½ times your body weight.” That means a 180-pound man will put 270 pounds of pressure on his knees with each step he takes. “Add an incline, and the pressure is even greater: the force on each knee is two to three times your body weight when you go up and down stairs, and four to five times your body weight when you squat to tie a shoelace or pick up an item you dropped.”

Going back to our example before, using this formula, that extra 5.4 pounds (the difference between typical ceramic plates and ShotStop’s Duritium® III+PS inserts) actually becomes 8.1 pounds of pressure on the knees when on level ground. Throw inclines or stairs or other activities into the mix, and that 5.4 pounds turns into 20 or even 25 pounds of combined pressure on the joints.

Why Add 20-25 Pounds of Unnecessary Weight?

It seems like a silly question, but law enforcement and military operators are making this choice every single day. Why? We believe it’s because of one of these three reasons:

  1.  Cost

    Unfortunately, price is often a (if not THE) top priority when purchasing body armor. Government contracts are driven by price, and when you consider initial price above everything else, ceramic is typically the less expensive option. But, as explained in this article about the price versus lifetime cost of body armor, a lower initial price does not mean a less expensive purchase.

  2. History

    No one wants to be caught up in the “it’s the way we’ve always done it” mentality, but we know it’s extremely difficult to get out of that system. Whether it’s a solid relationship with a salesperson or company that you don’t want to lose, or it’s just too hard to convince people to consider something different, change is hard.

  3. Education

    Directly connected to both #1 and #2 above, we believe the main reason those in law enforcement and military buy heavier body armor is because of a lack of education. It’s not to say they are uneducated...it’s about the fact that the body armor industry has long been the same. Steel and ceramic are the big gorillas of the industry, and without a full understanding of how polyethylene and composite body armor works, it’s a challenge to really know what is the best decision for you and your team.

Get Educated About Body Armor

If you’ve made it this far in this post, you’re already learning. Understanding the impact of weight on the body and joints is just as important as your knowledge of the stopping power of a body armor plate. As is realizing that added pressure to the joints caused by heavy body armor does in fact make a huge impact on the mobility, survivability, and even long-term medical issues of your team.

There are many more areas to address besides body armor weight. However, this a good example of “what you don’t know CAN hurt you.” We highly encourage you to check out all our resources on this website, from blogs about body armor to educational body armor videos. And, please know that we’re always willing to answer any questions. Just contact us or connect with one of our dealers.