Variabilities of salivary human herpesvirus 6, 7, and secretory immunoglobulin A levels from pre- to post-competition periods in baseball players.

Background: Persistent physical fatigue (PPhF) accompanying daily intensive training often results in underperformance. While salivary secretory immunoglobulin A (SIgA) has been traditionally used as an immunological marker, salivary human herpesvirus 6 and/or 7 (HHV-6/7) have recently been presented as "microbiological" markers of PPhF. This study aimed to examine the monthly variabilities of salivary HHV-6/7 levels and the difference with SIgA along the training periodization.

Methods: A total of 27 healthy male university baseball players (N.=17) and non-players (student staff, N.=10) were followed up for 4 months (August, pre-competition period; September and October, competition period; November, post-competition period). The main measures were subjective and objective fatigue parameters (questionnaires and performance tests), and salivary HHV-6/7 and SIgA levels.

Results: The fatigue parameters indicated a decrease in athletic performance from August to September due to PPhF during high intensity training in August. Two-way repeated analysis of variance showed that salivary HHV-6 and -7 levels were higher in players compared to non-players (P<0.05). Salivary HHV-6 levels gradually decreased (P<0.05), whereas HHV-7 levels remained unchanged (P>0.05). Salivary SIgA levels were higher in players rather than in non-players (P>0.05), and the levels did not change (P>0.05).

Conclusions: Our findings suggest that salivary HHV-6/7 levels, specifically in HHV-6, reflect the degree of PPhF independently of SIgA levels. As saliva can be collected anywhere, periodic monitoring of salivary HHV-6/7 levels may be easily applicable for assessing PPhF beside sports field and allow appropriate conditioning.