Does mononucleosis decrease athletic performance?

In my prior post, I argued that the decreased performance of Roger Federer and Justine Henin (and myself) may be related to mononucleosis. Rather than purely speculate, I did a quick review to see what has been published on this topic in the medical literature:

Article 1:

Bailey DM, Davies B, Budgett R, Gandy G. Recovery from
infectious mononucleosis after altitude training in an
elite middle distance runner. Br J Sports Med.
1997 Jun;31(2):153-4.

Examined the impact on a long distance runner who contracted mono. He had worsening of several physiological parameters, which never fully recovered (measured ~5 months later), but did recover much of his actual athletic
performance, running a personal best in the 1500k run 10 months after he caught mono. Conclusion: suggests that athletes can regain a high level of function after mono, even if their physiologic parameters do not fully recover

Article 2:

Gleeson M, Pyne DB, Austin JP, Lynn Francis J, Clancy RL,
McDonald WA, Fricker PA. Epstein-Barr virus reactivation
and upper-respiratory illness in elite swimmers.
Med Sci Sports Exerc. 2002 Mar;34(3):411-7.

This study is more of what I was looking for.  They looked at
14 elite male swimmers. Of them, 11 had prior infection with
Epstein Barr Virus.  They tracked the swimmers during a period
of intensive training, and found that just before the swimmers
would get sick with an upper respiratory infection, they would
have recurrences of Epstein Barr Virus.  It's not conclusive,
but it does suggest that for athletes a prior history of mono,
the virus never leaves your body, and that the virus will have
a tendency to resurface during periods of intensive training.


So, how does this impact my interpretation of Federer, Henin,
and myself?  I am sure there are other equally valid models
out there, but the model I am proposing is that when an
athlete (or borderline athlete in my case) gets mono, they may
be able to sustain short periods of intense exercise, but that
long term sustained intensity increases the probability of the
virus recurring, which makes long periods of sustained effort
substantially more difficult.  Because of this, athletes would
require longer periods of sustained rest.

Like most people, I am assuming Henin will come back at some
point, and just may need a year or two to let her body recover.
If I were advising Federer, I would also advise him to take
more time off.  Because he is so good, he tends to stay longer
in tournaments than most other players (since he makes the semis
or finals of essentially every tournament he enters).  I think
he would be better served by playing just the slams and a few
other ATP Masters Series events, but otherwise stay well rested.
He has nothing to prove at this point by playing a longer
schedule, and I think it will wear him out.