Disruption to our
circadian rhythms due to a mismatch
between environmental influences,
such as exposure to light or
mealtimes, and our internal 24-hour
clock (circadian rhythm) is a
possible cause of cancer. However,
the cancer risk can be considerably
reduced by physical activity. This
positive effect might be
particularly strong for exercise
done in the morning – that is the
main finding of a recent study
conducted by MedUni Vienna’s
Division of Epidemiology in
collaboration with the Barcelona
Institute for Global Health (ISGlobal)
and recently published in the
prestigious International Journal of
Cancer.
Studies indicate a possible
correlation between factors that
disrupt our circadian rhythms, such
as exposure to light during the
night or eating late in the evening,
and the risk of developing cancer.
Furthermore, studies have repeatedly
demonstrated that regular moderate
physical exercise can significantly
reduce cancer risk. However, so far
it has not been clear whether the
time of day when physical activity
takes place plays any significant
role.
Morning exercise protects – late
chronotypes in particular
In collaboration with the Pompeu
Fabra University in Barcelona and
Manolis Kogevinas and Gemma
Castaño-Vinyals from the Barcelona
Institute for Global Health (ISGlobal),
lead author Jakob Weitzer and
co-author Kyriaki Papantoniou from
the Division of Epidemiology of the
Medical University of Vienna have
investigated the hypothesis that
sporting activities in the morning
potentially reduce the risk of
prostate and breast cancer more than
sporting activities at other times
of day. The hypothesis is based on
results from an experimental study
showing that physical activity in
the afternoon or evening can delay
the melatonin rhythm.
The human body primarily produces
the hormone melatonin during the
night and some studies have
associated this hormone with a lower
cancer risk.
The team of scientists investigated
this question with 2,795
participants in the population-based
Multi-Case Control Study (MCC-Spain).
They found that the protective
effect of exercise on the risk of
developing prostate or breast cancer
is potentially greatest when the
physical activity takes place
between 8:00 – 10:00 in the morning.
However, in men this effect was just
as strong for regular sporting
activity in the evening (19:00 –
23:00 hrs.)
The participants' chronotypes, that
is to say their preferences for
sleep and activity at a particular
time of day, likewise influenced the
results: morning exercise (8:00 –
10:00) appeared to be particularly
good for participants who
essentially prefer to be active in
the evening – so-called "owls" or
late chronotypes. "The timing of
physical activity obviously has an
effect upon the rhythm of sex
hormones and melatonin, as well as
on food metabolism. That might
explain our results," point out the
researchers.
"Although these new insights cannot
be used as a basis for determining
the ideal time of day to exercise in
order to lower one's cancer risk, in
general one can reduce one's cancer
risk significantly just by
incorporating at least 150 minutes
of moderate physical exercise into
one's weekly routine."
Service:
International Journal of Cancer
"Effect of time of day of
recreational and household physical
activity on prostate and breast
cancer risk (MCC Spain Study)."
Jakob Weitzer, Gemma Castaño‐Vinyals,
Nuria Aragonés, Inés Gómez‐Acebo,
Marcela Guevara, Pilar Amiano,
Vicente Martín, Ana Molina‐Barceló,
Juan Alguacil, Victor Moreno,
Claudia Suarez‐Calleja, José Juan
Jiménez‐Moleón, Rafael Marcos‐Gragera,
Kyriaki Papantoniou, Beatriz Pérez‐Gómez,
Javier Llorca, Nieves Ascunce, Leire
Gil, Esther Gracia‐Lavedan, Delphine
Casabonne, Virginia Lope, Marina
Pollán, Manolis Kogevinas.
https://doi.org/10.1002/ijc.33310
Release: Mag. Thorsten Medwedeff,
Communications and Public Relations,
Medical University of Vienna