Résumé
This study investigated the effect of living (summer vs. winter) and working (morning vs.
afternoon) in a hot environment on markers of immune function and forearm strength.
Thirty-one healthy male gas field employees were screened before (between 05:30 and 07:00)
and after their working day (between 15:30 and 17:00) during both seasons. Body core
temperature and physical activity were recorded throughout the working days. The hot
condition (i.e. summer) led a higher (p≤0.05) average body
core temperature (~37.2 vs. ~37.4 °C) but reduced physical activity (−14.8%) during the
work-shift. Our data showed an increase (p≤0.05) in
lymphocyte and monocyte counts in the summer. Additionally, work-shift resulted in
significant (p≤0.001) changes in leukocytes, lymphocytes and
monocytes independently of the environment. Handgrip
(p=0.069) and pinch (p=0.077)
forces tended to be reduced from pre-to post-work, while only force produced during
handgrip manoeuvres was significantly reduced (p≤0.05)
during the hot compared to the temperate season. No interactions were observed between the
environment and work-shift for any marker of immune function or forearm strength. In
summary, working and living in hot conditions impact on markers of immune function and
work capacity; however by self-regulating energy expenditure, immune markers remained in a
healthy reference range.