It is a list of players sure to frighten NFL general managers, fans, and even fantasy football enthusiasts.

Green Bay Packers left tackle Bryan Bulaga, Denver Broncos center Dan Koppen, New Orleans Saints wide receiver Joe Morgan, San Diego Chargers receiver Danario Alexander, and Philadelphia Eagles wide receivers Jeremy Maclin and Arrelious Benn top the list.

Examining the knee of a pro athleteAll of these players have suffered season-ending ACL injuries in the first weeks of NFL training camps.

Does this list represent a spike of injuries compared to previous years, as many NFL pundits claim? If it is a real change in injuries, are the players themselves somehow to blame?

Is the CBA to blame?

Conventional wisdom seems to suggest that the collective bargaining agreement reached between NFL owners and players in 2011 created the rash of ACL tears. The new CBA limited teams’ offseason workouts to nine weeks and cut back on practice hours and contact in the preseason.

Theoretically, these changes addressed concerns about the long-term effects of concussions. Did they inadvertently create a different injury concern?

Is this a real spike in injuries?

First, it is important to know if this apparent surge is real. Almost exactly two years ago, I wrote a column in this newspaper addressing a similar surge of Achilles injuries. I urged caution about reading too much into an apparent injury trend without waiting a few years to see if it was only an anomaly. While there have been several Achilles ruptures since then, we haven’t heard anything to suggest that they are now a perpetual problem.

Second, a glimpse at each team’s roster suggests a more plausible statistical explanation. Each team can bring 90 players into its training camp. That roster gradually becomes 53 players by Week 1 of the regular season. Larger rosters create a larger pool of players to get hurt.

How do football players tear their ACLs?

Looking at the nature of ACL injuries – how they occur – might offer the best explanation, though. Athletes usually don’t tear the ACL when they are tackled. These are largely noncontact injuries. A player lands from a jump with the knee extended and his knee buckles. Or he runs, plants his foot to change direction, and his knee gives way.

Read the descriptions of the injuries of those players mentioned earlier. Almost all of them suffered their injuries in one of these two manners.

Wide receiver on grass football fieldThe larger number of ACL tears early in camp compared to any other point in the season is likely real, but not due to players having more free time in the offseason and reporting out of shape. These are elite athletes who are paid millions of dollars to play football. It is a dream job, and most of them train hard to make their teams and win championships.

All of the reps in the weight room and sprints on a track do little, though, to prevent ACL injuries. That offseason training does not prepare them for football maneuvers. They have little ability to replicate the awkward landings when defenders bump them in mid-air or the sudden cutting required when they step into passing lanes.

Suddenly in the first practices in training camp, these situations arise, and players tear their ACLs.

Is there a solution?

Rather than returning to the old offseason training schedules, there might be a simpler way for teams and players to cut down on these injuries.

Joel J. Gagnier, ND,MSc,Ph and others published a study in this month’s American Journal of Sports Medicine, compiling data from 14 individual research studies on ACL injury programs. These programs usually consist of a small number of exercises designed to improve balance, strength, neuromuscular coordination and more. They found that these programs appeared to decrease the incidence of ACL tears by about 50%.

Since these are noncontact exercises, teams could add these programs into their offseason minicamps. To be effective, players need to perform them daily for months in the offseason and during the season. If a few extra minutes of exercise could improve the players’ risk of suffering season-ending ACL tears, I’d bet many of the players would gladly do it on their own.

It will take years to truly know if we are witnessing a real surge in ACL injuries in the NFL. Whether or not the CBA had any role in the injuries will be even harder to determine. Regardless, a simple exercise program might soon prove to have a greater effect on these injuries than any practice or offseason changes.

The Dr. David Geier ShowDo ACL injury prevention programs work? In the Zone segment from Episode 58 of The Dr. David Geier Show

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Note: A modified version of this post appears as my sports medicine column in the August 16, 2013 issue of The Post and Courier.

Special thanks to Prateek Prasanna for his assistance with this column.