Sport Sciences for Health
Electrocortical activity during stretch reﬂex in athletes
· Francesca Pretari
· Giovanni Cugliari
Received: 20 December 2017 / Accepted: 16 May 2018
© Springer-Verlag Italia S.r.l., part of Springer Nature 2018
Background To evaluate timing and characteristics of electrocortical activity during stretch reﬂex evocation of the quadri-
ceps femoris at diﬀerent body postures.
Methods Twenty athletes were subjected to reﬂex hammer percussions on patellar tendon, in a random time sequence, in
seated and supine decubitus postures. 745 ms of acquisition were evaluated for data analysis: 200 ms of pre-stimulation,
45 ms relative to the elapsed time from stimulation to the end of the muscular contraction, and 500 ms of post-stimulation.
First, a scalp-map analysis, considering channels data, was performed; second, independent component analysis decomposi-
tion was applied to all 16 channels. To highlight the diﬀerences among two conditions (pre- and post-stimulation) and two
sessions (seated and supine decubitus postures), a two-way analysis of variance was used. Time–frequency analysis has been
applied to identify the density of the frequencies as a function of the time, instant by instant.
Results Fast alpha, beta, and gamma frequency bands showed a greater electroencephalographic activity after the stimula-
tion. Seated posture showed a greater activation than the decubitus supine posture. Time frequency analysis highlighted an
higher electrocortical activation for 160 ms as well as from about 250–300 ms at all frequency bands after the stimulation.
Conclusions Our ﬁndings improve the understanding of the neurophysiological dynamics following the stretch reﬂex after
concussion of the patellar tendon, executed in diﬀerent postures, considering scalp-map, power spectra, and timing of activa-
tion. The use of scalp-map and power spectra analysis techniques represents a sophisticated use of advanced signal processing
methodologies to analyze brain activity during movement and in speciﬁcity in sport science.
Keywords Stretch reﬂex · EEG · Athletes · Neuromuscular system · Body postures · Time/frequency analysis
ANOVA Analysis of variance
CNS Central nervous system
PNS Peripheral nervous system
ROI Region of interest
Stretch reﬂex assumptions
Stretch reﬂex evaluation is part of the physical and neu-
rological examinations to determine an injury in the CNS
(central nervous system) or PNS (peripheral nervous sys-
tem). All the external disturbances are rapidly neutralized
by stretch reﬂex (of spinal origin) by a cortical networks
that contribute on its modulation. Stretch reﬂex is necessary
for the muscle stability: a pool of activated motor neurons
changes in each stimulation to ensure a greater conduction
velocity. The muscle spindle is the source of somatosensory
startup and its capacity is directly proportional to the rate of
muscle stretching; It also aﬀects the conduction velocity of
the stimulus and the length of the contractile mass involved
during the reﬂex . Whenever you perceive an external
stimulus, a cortical activation originating from mechano-
receptors is recorded , and then, there is a consistency
among stimulus and brain activity.
Electronic supplementary material The online version of this
article (https ://doi.org/10.1007/s1133 2-018-0471-0) contains
supplementary material, which is available to authorized users.
* Giovanni Cugliari
SUISM, University School of Hygiene and Motor Sciences,
University of Turin, Corso Trento 13, 10129 Turin, Italy
Department of Statistics and Quantitative Methods,
University of Milano-Bicocca, Piazza dell’Ateneo Nuovo 1,
20126 Milan, Italy
Department of Medical Sciences, University of Turin, C.so
Dogliotti 14, 10126 Turin, Italy