| This
study was designed to investigate the relationship between Actigraph
counts and running speed; and to describe differences due to accelerometer
position on the body and due to exercise modality. Eleven physical
education students (age, 25.1 ± 3.7 years; height, 1.73 ± 0.10 m;
body mass, 70.8 ± 10.8 kg) completed two exhaustive exercise tests
(continuous and intermittent), with MTI accelerometers mounted both
at the hip and ankle. Exercise consisted of running for 3-min at incremental
speeds until volitional exhaustion. During both exercise tests, the
relationship between the ActiGraph outputs worn at the hip and speed
was linear in the range 1.1 - 3.3 m·s-1 (r2
= 0.94 and 0.95, p < 0.01 for continuous and intermittent exercise
respectively). A coefficient of determination of r2 = 0.97
(p < 0.01) was found with ankle wearing from walking, jogging and
running at high speeds. There was a body placement effect at all absolute
speeds (p < 0.01); but no exercise effect on accelerometer counts
and no interaction between placement and exercise (p> 0.05). The
ActiGraph seems to be a reliable tool for estimating a wide range
of activity or exercise intensities. An ActiGraph worn at the ankle
may be more appropriate to reflect normal human movement.
KEY
WORDS: Physical activity, joint kinematics, hip, ankle.
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