Foster, Stewart, Matthews: what is the common thread?

Arian Foster, Jonathan Stewart, and Ryan Matthews are all out with leg injuries.  Both Stewart and Matthews are out with knee sprains and Foster is down with the infamous hamstring injury.


The Science

Running back is arguably the most injury susceptible position there is.  Their combination of speed, repetitions, and contact endured is not only unrivaled in football but is likely unrivaled in any other sport or activity.  With the extrinsic (things coming from the outside) factors that these guys face such as defensive lineman, linebacker and full speed defensive backs, who needs intrinsic (things coming from the inside) factors!

When you look at these 3 backs, their intrinsic factors are exactly why I think you will see them on the injury report often.  The average NFL running back weighs about 215 lbs.  Foster, Stewart and Matthews are 229 lbs, 235 lbs, and 218 lbs respectively.  While Matthews is close, my guess is if he got on a scale right now, it’s not that close.  In any case, much of the force for a running back is absorbed by the major muscles in their legs.  These muscles are primarily their quadriceps and hamstrings which are the major movers and protectors of the knee.  Some may argue that the gluteal muscles should be included but I consider these muscle more important in the pelvic and trunk area and less susceptible to injury.  The reason why you see so many knee injuries is that these backs are wearing these muscles out with all of the stress they put on them.

Our muscles are the first line of defense to our joints, I call them the body guards.  If your quads and hamstrings are strong and fresh, you can jump, cut, run and your knee-joint won’t get any of that rough impact because those big, strong, energy filled body guards (quads and hamstrings) are protecting the knee-joint.  However as they fatigue or become weak after a hit or a fall, your knee-joint has loss its first level of defense.  In many cases this scenario ends in a knee strain which means the muscle couldn’t keep up and had to work so hard that it failed and needs a break.  (Strain always refers to muscle-not ligaments). I think it is understandable how this is more likely to happen if you are carrying 15-20 lbs of extra weight.

Your joints next line of defense are the ligaments.  After muscles fail, ligaments jump in and do what they can.  Ligaments can only offer a certain amount of protection and if the force is too great (too hard a cut, a direct blow to the knee, too much force from a hard fall), they will also fail.  When the ligament fails, it is called a sprain (Sprain always refers to ligaments-not muscle).  In many cases this is why you see the reports say a sprain/strain injury–it signifies that both the muscle and ligament failed in some way (or in some cases it means the trainer or doctor aren’t sure and just want to let the MRI do all the work, but you didn’t hear that from me)

When sprains or strains are severe they become tears (although technically there may be some level of tearing in the less severe sprains and strains also).  Luckily these players are not dealing with tears.

With most running backs averaging about a 4.6 second – 40 yard dash time, making at least 1 cut during each play and being contacted on nearly every touch; the load on these major muscles are immense.  Outside of the athletic world a man who is about 6 feet tall should roughly weigh about 180 lbs.  Many of these backs are shorter than 6 feet and in fact if you average these 3 backs, they are an average height of about 5′ 11″.  While we know that they have more muscle mass than the average man, we also know that muscle is dense  and although many of their additional pounds may be muscle, the bottom line is that those joints are made to carry about 180 lbs.  If you work out, then you are likely aware that BMI calculations are pretty much blind.  You can have virtually no fat and be 235 lbs and be considered obese by BMI calculations.  Unfortunately your joints are blind too.  They don’t admire your muscular physique, they simply carry you, move you, absorb the shock when you land, and take the impact when your hit.

Scientifically speaking, these guys are simply carrying too much weight for the duties their bodies require to be a running back.  With 5-10 more pounds either, Foster or Stewart could play outside linebacker.  The difference is a linebacker cuts much less often, runs for much shorter distances, and delivers impact (rather than receive impact) in most cases.  There is a reason that these draft scouts and strength/conditioning coaches put these players on the scale.  There are ideal weights for different positions and frankly these 3 are above that weight and are likely to continue to be at a higher risk for injury.

What you need to know

Although my description above makes these backs similar, they are very different when it comes to how it impacts you.  Foster used to be a fantasy stud but at 229 lbs and 28 years old, I feel like he is headed to Steven Jackson comparisons (when’s the last time Jackson played a full season?).  Running backs slow down around 29 or 30 years old anyway, but the heavier ones start a little earlier.  He will continue to play for 2-3 more years but at this point I wouldn’t listen to any fantasy advice that considers him to still be an elite fantasy option.  I also wouldn’t expect the Texans to do much without him….their backfield outlook is gloomy Blue (get it).

Ryan Matthews has a slightly better outlook only because he is 26 years old and is still at a point where he may change regimens and slim down.  I still would watch his weight on the official side but also with the eye test.  If he appears to be adding muscle or fat, I would leave him alone. He has already shown to be somewhat injury prone and is not near the stud that Foster was a few years ago.

As for Stewart, not much to talk about.  He only made the conversation because of his weight and the fact that he is also injured right now.  I don’t think I have to tell anyone who is smart enough to read this entire piece what to do with Stewart.  Maybe one day Carolina will get a running back that makes sense.  For a running back, DeAngelo Williams is a senior citizen; and Stewart and Tolbert are obviously enjoying that Carolina barbecue.  Please don’t hurt me……I do live in the Carolinas…..on second thought no I don’t.

All things considered, each of these backs will be back this season, but that is not the point.  What you must consider if you rely on them for fantasy or rely on them to help their teams win; is that they are not reliable.  These minor injuries and day-to-day statuses will continue with them until they decide to trim down.