Philips DL8790 User Manual page 66

Problem
66
Possible cause
Blood flow in the skin can
be impacted by increased
pressure on the small blood
vessels in the skin (e.g.
when the watch strap is too
tight).
Blood flow in the skin can
be temporarily reduced
during warm-up exercises
as more blood is directed to
the muscles.
Solution
Try loosening the strap a notch to
relieve some pressure, but make
sure the watch still retains a snug fit.
Disregard inaccurate measures
during warm-up exercises and
provide some time for the blood
flow to the skin to adjust to the
exercising conditions.