european college of sport science

Saturday, June 27th, 2009
Discussion: This study showed that ETS can induce muscle cramp to the calf muscles, and that the TF of ETS was a reliable measure to
assess the risk of calf muscle cramp susceptibility. Most subjects cramped within a 3 Hz difference between tests, but some had up to a
15 Hz difference. Interestingly, those who reported a lower susceptibility to cramp had a greater difference in TF between tests, suggesting
that the test is more reliable in those who are more susceptible to cramp. Factors thought to influence muscle cramp, such as electrolyte
disturbance, dehydration, environmental conditions and fatigue should be examined using ETS.
1. Bertolasi L, et al. (1993) Ann Neurol, 33, 176-180.
2. Minetto M, et al. (2008) Muscle Nerve, 37, 90-100.
LOCALLY CONFINED CALCIUM DEPENDENT MORPHOLOGICAL CHANGES TO MITOCHONDRIA OF THE MOTOR END-
PLATE DUE TO CARBACHOL STIMULATION.
VOIGT, T.
UNIVERSITY OF BERN
Disturbance of the motor end-plate calcium homeostasis for hours leads to vacuolisation of the mitochondria in the vicinity of the motor
end-plate (MEP) and necrosis of muscle fibres. Little is known, however, about the onset of these morphological changes due to this
disturbance. To improve our understanding of the MEP calcium homeostasis, it would be beneficial to temporally and topographically
pin-point the first visible signs of morphological changes to mitochondria. In order to disturbe the MEP calcium homeostasis, omohyoid
muscles of mice were stimulated for 1 to 30 minutes with the acetylcholine agonist carbachol which leads to an inward current of free
calcium in the MEP. The fibre-type-specific morphological changes to the MEPs and mitochondria were evaluated using light- and electron-microscopy
and compared with laser-scanning live-recordings of Rhod2-AM labeled mitochondria of MEPs during carbachol stimulation.
Localised calcium dependent contractures of different severity underneath the motor end-plate were observed within some but not
all muscle fibres depending on the duration of carbachol incubation. But the most prominent contractures were confined to slow muscle
fibres. The mitochondria in the MEP as well as in the contracture zone underneath the MEP of those muscle fibres with strong contractures
i.e. mostly of type I fibres manifested electro-translucent spots in the matrix whereas the mitochondria outside the contracture zone
looked normal. The live-recordings during the carbachol stimulation showed sequestering of calcium into the mitochondria of the MEP
area wherease the calcium content of the mitochondria outside the MEP did not change. We interpret this as a first sign of calcium overload
of the mitochondria and as a hint towards differences in the handling of the calcium homeostasis in different muscle fibre types.
ACTIVATION OF THE HUMAN PRIMARY AND SECONDARY SOMATOSENSORY CORTEX FOLLOWING TACTILE STIMULA-
TION
ONISHI, H., SOMA, T., OYAMA, M., KIRIMOTO, H., FURUSAWA, A.A., OISHI, M., KAMEYAMA, S.
NIIGATA UNIVERSITY OF HEALTH AND WELFARE
Introduction: Our goal is to examine the sensory feedback from periphery to generation of the movement evoked cortical magnetic fields.
We reported that the first component of the movement evoked magnetic fields (MEF 1) was due not to the onset of joint movement but to
that of muscular contraction. However, the generators of the second and third components of MEF (MEF 2 and 3) that observed with long
latency after electromyographic onset are not fully understood. In this study, MEG recordings were performed to investigate the neural
mechanisms following the tactile stimulation of the index finger.
Subjects and Methods: Ten healthy male subjects (mean age 29.2±10.3 years) participated in this study. All subjects had given their
written informed consent, and the study was approved by the ethics committee at our university. For MEG measurement, we used a
306ch whole-head MEG system (Neuromag, Elekta, Finland) and tactile stimulator that was made of non-magnetic materials (KGS, Japan).
MEG signals were sampled at 1000Hz with band-pass filtering from 0.03 to 330 Hz. The averages of above 300 epochs for SEFs
were obtained. Tactile stimuli were applied to the tip of right index finger. Tactile stimulation was used the four teeny pins with 1.3mm
diameter and 0.7mm high. The distance of each top of pins was set at 2.4mm. Inter stimulus interval was set at 2 second and the pressurization
was continued during 1 second. For analysis of SEF, the bandpass filter was set from 0.5 Hz to 50 Hz. The sources of the components
of interest in the SEFs were estimated as the equivalent current dipoles (ECD). The ECD locations and moments were calculated
using a spherical conductor model of 3D axes determined with the fiducial points, i.e. the nations and bilateral preauricular points. We
accepted ECDs with a goodness-of-fit > 90% for analysis.
Results: Clear SEF signals were recorded from contralateral hemisphere for all subjects at around 57ms and 140ms after pressurization
(57.4±12.7 ms and 140.0±14.6 ms) or depressurization (56.9±13.3 ms and 144.0±17.0 ms), and these ECD locations were in area 3b.
Moreover, long latency responses (169.4±33.0 ms after pressurization, and 172.2±36.7 ms after depressurization) were identified in
ipsilateral hemisphere, corresponding to secondary somatosensory cortex (S2).
Discussion: In this study slight intensity of tactile stimuli was used, and a clear SEF signal was recorded from bilateral hemisphere after
pressurization and depressurization. The long latency activation was detected clearly at ipsilateral S2. S2 was speculates to serve a
higher level of cognitive function in somatosensory information processing, such as attention, objective recognition and integration of
nociceptive and non-nociceptive inputs. In this study, we could record S2 activation without attention or recognition. These methods and
results may clarify the S2 function and the generator of MEF2 and 3 during voluntary movement.
A METABOLOMIC APPROACH TO INVESTIGATE THE METABOLIC CHANGES INDUCED BY ACUTE AND CHRONIC
PHYSICAL EXERCISE IN YOUNG WOMEN
DUGUE, B., ENEA, C., PETITPAS-MULLIEZ, J., BOILDIEU, N., EUGENE, M., SEGUIN, F.
UNIVERSITY OF POITIERS, FRANCE
Metabolomic is a comprehensive method for metabolite assessment, measuring the overall metabolic signature of biological samples.
We used this approach to investigate biochemical changes due to acute and chronic physical exercise.
Twenty-two women using the same oral contraceptives were allocated to an untrained group (n=10) or a trained group (n=12), depending
on their physical training background. The subjects performed a short-term intensive exercise test (Wingate anaerobic test). Urine
specimens were collected before and 30 min after the test. The samples were analysed by 1H NMR spectroscopy and multivariate statistical
techniques were utilized to process the data.
OSLO/NORWAY, JUNE 24-27, 2009 559