european college of sport science

PP-BM04 Biomechanics 4
ever, these differences were not observed from the force plate signals. This may indicate that different aspects of the movement may be
measured by each monitoring system of human motion. The real motion human tracking is a promising technique of evaluating and
distinguishing between CAI and stable ankles which may be also applicable in clinical settings outside a laboratory.
References
1.Olmsted LC, et al. J Athl Training. 37: 501-506, 2002.
2. Rioul O and M. Vetterli. IEEE Signal Processing Mag. 8: 14-38, 1991.
3.Zhu R and Zhou Z. IEEE Trans Neural Syst Rehab Eng. 12: 295-302, 2004.
APPLICATION OF A CONTACT-TYPE MUSCLE HARDNESS METER DURING VOLUNTARY ISOMETRIC CONTRACTION
MURAYAMA, M., ITO, R., UCHIYAMA, T., YONEDA, T.
1. INST. OF PHYSICAL EDU., KEIO UNIV., 2. FAC. OF SCIENCE & TECHNOLOGY, KEIO UNIV., 3. SCHOOL OF HEALTH & SPORTS SCIENCE, JUN-
TENDO UNIV.
Muscle hardness is a possible index of muscle conditioning. Several methods of evaluating muscle hardness have been reported, for
instance, the indentation method. Previous studies have demonstrated that a high correlation between muscle contractile tension and
muscle hardness is obtained when the indentation method is used for evaluation in humans (1, 2, 3). However, it is difficult to assess the
real-time change in hardness, e.g., during muscle contraction. Furthermore, joint movement or muscle shaking that occurs during a
contraction increases the difficulty in evaluating hardness by the indentation method. We developed a contact-type muscle hardness
meter using an ultra-slim pressure sensor which assesses the change in muscle hardness continuously. The purpose of the present
study was to compare the change in muscle hardness during isometric contraction evaluated by the new contact-type device and the
conventional indentation device.
Contact-type muscle hardness (CMH) meter: The hemisphere hard rubber tip was bonded with the front of the ultra-slim pressure sensor
and then bonded with a metal plate. This hardness meter was set on the muscle belly of the biceps brachii and bound with adhesive
non-elastic surgical tape. Therefore, it could continuously detect the internal pressure change with muscle activation. Indentation type
muscle hardness (IMH) meter: The muscle hardness meter was connected to the stage controller system. Mechanical indentation with 25
mm amount was performed with a remote control. The muscle hardness value with indentation was calculated by measuring the slope
of the force/displacement relationship that ranged from the length eliminated the thickness of subcutaneous tissue up to 15% muscle
thickness (4). Measurement of 2 types of muscle hardness during isometric contraction: Six healthy males performed isometric contractions
in the range 20–100% of the maximal voluntary contraction (MVC). Two types of muscle hardness in the elbow flexor muscles,
namely, CMH and IMH, were simultaneously measured while the target contraction level was sustained.
The measured mean relative CMH was linearly related to the isometric force (r = 0.856). On the other hand, the relationship between the
mean relative IMH and the isometric force was non-linear even when IMH was increased up to 90% MVC. The mean relative CMH also
showed a non-linear relationship with the mean relative IMH (r = 0.862). Therefore, it was suggested that CMH could be used to assess
the extent of muscle contraction at a higher intensity than IMH. We conclude that the contact-type muscle hardness meter can be used to
quantitatively evaluate muscle hardness during isometric contraction, and CHM can be used to estimate the extent of contraction.
References.
1. Arokoski et al. (2005) Physiol Meas, 26, 215-28.
2. Leonard et al. (2004) J Electromyugr Kinesiol, 14, 709-14.
3. Murayama et al. (2004) Adv Exer Sport Physiol, 10, 128.
4. Murayama et al. (2008) Proceeding of ECSS 08, 339.
THE EFFECT OF DYNAMIC STRETCHING ON MUSCLE PERFORMANCE AFTER FATIGUING EXERCISE
KUNO-MIZUMURA, M.
OCHANOMIZU UNIVERSITY
Stretching is one of common exercise widely performed during warm up or cool down. It is also widely accepted that stretching would be
useful strategy to recover from muscle fatigue; however, it was not fully elucidated by scientific evidences. The purpose of this study was
to examine the effect of dynamic stretching on muscle fatigue using EMG analysis. Subjects were eleven healthy females. Subjects visited
our laboratory three times including familiarization for testing protocol as the first visit. On the second and the third visit, subjects were
performed 30% maximal voluntary contraction (MVC) of isometric plantar flexion until exhaustion (1st EX) with active dynamic stretching
(ST) and without stretching (CON). After 1st EX, subjects performed active dynamic stretching for five minutes for ST. One minutes after
active dynamic stretching, subjects performed 30%MVC of isometric plantar flexion again until exhaustion (2nd EX). On the other visit,
subjects were asked to keep resting instead of dynamic stretching for CON. MVC forces of isometric plantar flexion were recorded before
and after 1st and 2nd EX for both ST and CON. MVC force decreased significantly after 1st and 2nd EX compared to the baseline. Exercise
time of 2nd EX decreased significantly than that of 1st EX for both ST and CON. However, % decline in the exercise time of 2nd EX was
significantly smaller for ST. Integrated EMG of lateral heads of gastrocnemius, medial heads of gastrocnemius, soleus, and tibialis anterior
muscle increased significantly with time for both 1st and 2nd EX during both ST and CON, while mean frequency of EMG signals
evaluated by FFT analysis decreased significantly with time for all exercise. Integrated EMG of soleus muscle during first 10% of exercise
time showed significantly lower level for ST than that for CON. In addition, mean frequency of medial heads of gastrocnemius decreased
earlier than that of iEMG increase with time for ST, although those two parameters of medial heads of gastrocnemius muscle changed
simultaneously for CON. From the results of this study, it is indicated that active dynamic stretching would be effective to reduce muscle
fatigue by modifying neuromuscular activity by active stretching.
THE RELATION BETWEEN EXERCISE STYLE AND ACTIVATED AREA DISTRIBUTIONS WITHIN HUMAN MEDIAL GAS-
TROCNEMIUS
EDAMATSU, C., IKEBATA, H., KAWAKAMI, M.
KURASHIKI UNIVERSITY OF SCIENCE AND THE ARTS
The purpose of this study was clarifying the relation between exercise style and activated area distributions within human medial gastrocnemius(MG).
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