Sleep Deprivation and Risk of Injuries

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A few days ago, I wrote this post describing some recent air travel stories.  Included was the plight of the Las Vegas Aces WNBA team whose travel delays heading toward Washington D.C. to play the Mystics ended up with the Aces cancelling their game - and a twitter storm of discussion over whether or not that should have been allowed.   At the time of this writing, the WNBA has not yet presented its decision on what will be the outcome of the Aces canceling the game - since they did ultimately make it to D.C. in time to physically be present.  The delay in the outcome of this saga is a bit surprising... twitter has been buzzing waiting to see what will happen... and it has huge playoff implications for both teams. 
The Aces released this (abridged) statement:  "To all of our WNBA fans around the world: We are so sorry that the Aces were not able to take the court tonight against the Washington Mystics. We trust that you know this decision was not made lightly...Given the travel issues we faced over the past two days—25+ hours spent in airports and airplanes, in cramped quarters and having not slept in a bed since Wednesday night—and after consulting with Players Association leadership and medical professionals, we concluded that playing tonight’s game would put us at too great a risk for injury. Naturally, the issue of player safety is of paramount concern for all involved in the WNBA..."

As a WNBA fan - I was sad that the game didn't occur.  If I had tickets, I'm sure I would have been disappointed, especially since people travel to get to games, and they canceled only an hour and a half before tip off.  But as a physical therapist who works with a WNBA team (and would never play any role in making the decision of if we would be playing), I think this was the right decision.  I didn't have enough research to back it up before - so now I've gone searching.  Full disclosure - I'm biased.  I searched for research relating sleep deprivation and fatigue to injuries.  I'm sure I could potentially find papers that would state the opposite outcome... but this is one of the problems with practicing evidence-based medicine.  For every paper that has an outcome, there could be differently designed papers that have the opposite outcome.  So here's what I found, and we can take it with a grain of salt...

1) Durmer et al wrote in a a 2005 about the "Neurocognitive Consequences of Sleep Deprivation."  They wrote about increased risk of car crashes in sleep-deprived males with injury severity and frequency of accidents similar to those of alcohol-related incidents.  This paper focused more on the chronically sleep deprived - people who sleep less than 7 hours per night consistently - though it does mention other types of sleep deprivation such as short term sleep deprivation for less than 45 hours or long term for greater than 45 hours.  Changes in mood, confusion, anxiety, and depression are noted issues across types of sleep deprivation.  Of key importance is that there was a correlation with decreased response time and increased rate of errors with multitasking... which is essential for sports participation.

2) Milewski et al in 2014 also examined more chronic sleep deprivation and found increased risk of injury in adolescent athletes who slept less than 8 hours compared to those who slept more than 8 hours.  Higher grade level in school (older kids) also had increased risk of injury in this study. 

3) Of course I did a search for the relationship between ACL injuries and fatigue...because in the women's basketball world, a torn ACL is considered one of the worst things that could happen. Last month, this brief article was published summarizing increased risk of ACL injury when jump-landing mechanics were assessed following aerobic exercise (acute bout of fatigue) which corresponded with 20% of local muscular fatigue.  It's hard to compare this to 25 hours of travel like the Las Vegas Aces underwent - but in that case we're talking about more of a full-body fatigue with increased risk because of the above-mentioned cognitive factors - in addition to this localized muscle fatigue which would potentially also be present from sleep deficits.  In 2008, Borotikar et al published this paper looking at central and peripheral fatigue influence on ACL injury in females. Again, the fatigue factor was not induced by air travel... it was caused by repeated squatting or jumping tasks, so the correlation is difficult to make.  This study was interesting because it looked at muscular (peripheral) fatigue as well as decision making (cognition/central fatigue) in tandem where previous studies had only looked at the impact of either type of fatigue on ACL injury.  Based on the length of the Aces travel, it is likely that they were mentally fatigued and muscularly fatigued... so it is absolutely reasonable to extrapolate from this particular study that their risk of ACL injury would have been increased by playing under their conditions.

I know there are plenty of people who say they should have played.  I understand those reasons... it's better for the league not to miss games, it's essential for fans to see their favorite players - especially since the teams only would meet in DC twice this season and it's close to South Carolina where Aces superstar A'ja Wilson played in college... South Carolina fans would really have to go to either DC or Atlanta to get to see her, and I saw a few posts online with some devastated fans that they couldn't see her play.  But the statement released by the Aces was clear that there was concern for injury - and thruthfully, if someone tore their ACL in this game - win or lose - that's a huge loss for someone's career and for the team finishing out the season.  Taking a single loss might just have been the best protection for the health of their team.

I can't believe we don't know what the league will do about this yet... but I'll go ahead and guess that the Aces will take the forfeit, the Mystics will get a win, the game won't be made up, there will likely be some financial penalty the Aces will have to pay to the Mystics for imposed costs... and the league will continue to move forward.  Even better - the WNBA players union will open up conversations in a few weeks for their collective bargaining agreement, and travel expectations are bound to be part of their negotiations moving forward.

The end of the WNBA regular season is rapidly approaching - last day is August 19th and then straight into the playoffs.  The blog may be a little heavy on WNBA basketball right now... and then I'll go through my end-of-season mourning period and return to more writing about physical therapy topics... at least until college basketball starts.  Can't wait to see what the league decides for the Aces... it could set a major precedent moving forward.