Leonard Fournette has been out since the first half of week 1 against the Giants when he was taken out of the game after straining his right hamstring. He returned to limited practice on Wednesday and might play Sunday against the Titans. However, hamstrings are notoriously sensitive and prone to re-injury. Even if he does play against the Titans, this could be an injury that lingers all season with an increased risk for re-aggravation.
To understand why, I’ll first get into how the injury happened and the critical role that the hamstrings play for Leonard Fournette, and finally the risk for ongoing irritation and re-injury.
Here we go…
I. Leonard Fournette Mechanism of Injury
Here’s a video of the play where Leonard Fournette was injured:
During this play, he suffered a small disruption in his right hamstring, referred to as grade I (“minor”) tear. This grade 1 tear could be in one of four muscles as “the hamstring” is actually a group of four muscles known as the hamstring group.
Two of the muscles, the semimembranosus (SM) and biceps femoris long head (BFLH) lie superficial:
While the other two muscles, the semitendinosis (ST) and biceps femoris short head (BFSH), lie underneath:
No information has been released on the specific muscle or muscles that were injured.
The injury most likely occurred when Leonard Fournette saw the traffic in front of him and was slowing down (decelerating) to change direction. Deceleration is the key role of the hamstrings as they serve to “brake” the forward swinging leg before it touches the ground (click here, here, and here for more info).
The hamstrings do this by contracting while lengthening aka an eccentric contraction:
This is in contrast to a concentric contraction where the muscle is contracting while shortening. Here’s a good visual showing the difference eccentric and concentric using the example of a biceps curl:
An eccentric contraction is significantly more stressful than a concentric contraction (fun fact: when you’re sore, most of the time it’s from the eccentric part of the lift). It’s no surprise that most hamstring injuries occur during the high stress, eccentric contraction, deceleration phase (click here, here, and here for more info).
Further, as Leonard Fournette was walking towards the sidelines, he was clearly clutching behind his right leg:
— Jordan Schultz (@Schultz_Report) September 9, 2018
The hand on the back of the leg and uncomfortable walk is a very common pose after someone tweaks their hamstring (if you’ve done it before, you may be wincing just looking at it) and a pose that’s seen all too often in the NFL – it has the highest prevalence of hamstring injury of any sport.
So those are the basics of Fournette’s hamstring injury and he could back this Sunday, putting his return to play timeline at two weeks. That’s right on the average for athletes using aggressive hamstring rehab programs (click here and here for more info).
However, even if he does come back, he faces some ongoing risks….
II. Potential for Re-Injury
The most reliable risk factor, by far, for future hamstring injury is a a previous hamstring injury. Digging through the injury history of Leonard Fournette, I wasn’t able to find any history of hamstring issues but Jaguars Coach Doug Marrone hinted at that in the post-game:
[The injury is] something he felt like he has had before [and] knows how to treat it
Research shows that players with a previous hamstring injury are two to six times more likely to have another strain (click here, here, here, here, here, here, and here for more info). Further, most of these re-injuries happen within the first two months after returning to sport with increased risk thereafter (click here, here, and here for more info). Some studies have shown that the risk for re-injuring a hamstring is three times higher than a non-injured player for up to a year after the initial strain.
You can see why I’m concerned about Leonard Fournette going forward this season. Regardless of his position or sport, he’s at high risk of re-injuring that hamstring for the next two months with increased risk for up to a year. Then you factor in that football, as I mentioned before, has the highest prevalence of hamstring injuries and the RB position requires constant deceleration and change of direction, constantly putting high stress on that hamstring.
Not the best recipe.
That risk is further compounded if the Jaguars are rushing him back to play because multiple studies show that shorter rehab time does correlate with an increased risk for re-injury (click here, here, and here for more info). That being said, all the indicators point towards the Jaguars medical staff handling Leonard Fournette really well, highlighted by the team erring on the side of caution last week and not playing him.
Lastly, another risk factor for Leonard Fournette is race. The research shows that athletes with an African origin (along with those of Aboriginal descent) have a significantly higher chance of straining their hamstrings (click here and here for more info).
With each of these reasons in mind, it wouldn’t surprise me in the slightest if Leonard Fournette does end up tweaking that same hamstring again at some point with TJ Yeldon again coming on in his stead.
III. The Final Take
All in all, Leonard Fournette looks to be on the verge of returning from his grade 1 hamstring strain and playing against the Titans. However, a hamstring strain is notoriously sensitive and prone to re-injury, especially within the first two months after initial injury, and Leonard Fournette plays a sport and position that puts constant high level stress on the hamstring via deceleration and change of speed/direction movements.
You combine those factors with his non-modifiable risk factors for re-injury and there’s a distinct possibility that we see this picture again: