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THE COMPARISON OF MUSCLE ACTIATION USING DIFFERENT TRAJECTORY

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elliptical trainer, also known as elliptical trainers or cross-training machine that combines a variety of the most popular home fitness equipment training action. "Oval" when the word comes from the oval shape of pedal movement, which is a kind of treadmill, stair climbing, cycling, skiing part of the action into one of the instruments. Elliptical machine allows you to exercise on the machine, as in the ski machine that glide, you can simply adjust the pedals to increase the slope to get more like climbing stairs or riding a bicycle pedaling sense.

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									        THE COMPARISON OF MUSCLE ACTIATION USING DIFFERENT TRAJECTORY ELLIPTICAL

                                             C-L Cheng, R-W Smith and T-Y Shiang
                                            Institute of Sports Equipment Technology
                                                 email: joelyn1212@yahoo.com.tw

INTRODUCTION                                                       During one step cycle, muscle activation of the rectus
The elliptical training machine creates a different movement       femoris primarily worked in the first and the third phase.
trajectory when compared to the treadmill and cycling.             EMG amplitude in Biceps femoris did not show a significant
Muscle recruitment activity is different when using the            difference. Tibialis anterior functioned in the stance phase,
elliptical trainer, treadmill and cycling. More and more new       and there was other evidence of activation in the third phase
designs of elliptical trainers are being produced and we can       (50%~75%). For the tibialis anterior, the largest increase in
see that each elliptical trainer has a different movement          EMG amplitude was in the forefront, and the differences
trajectory because of the changing pedal positions. Lot’s of       during the three positions were much more distinct than the
papers discuss elliptical training and how it affects              other three muscles. As for the gastrocnemius, the
cardiopulmonary training as well as the mechanism design           downward phase indicated the greatest activation. The
but there’re no investigations conferring different                tibialis and gastrocnemius activation sequences, moreover,
trajectories. Therefore, the purpose of this investigation is to   are a little different between subjects during elliptical trails.
examine the kinematics and biomechanics of different
movement trajectories by changing the pedal position.

METHODS
Five healthy male adults were recruited to train on the
elliptical machine. Lower limb kinematics was obtained
using 10-camera motion analysis system sampled at 100 Hz.
Muscle electromyography (EMG) data were collected from
rectus femoris, biceps femoris, tibialis anterior and
gastrocnemius using 4 EMG amplifiers at 1000 Hz.
The subjects performed a 2-minute warm-up to develop a
consistent pedaling speed and pattern. Data were collected
during a 30-second period following the warm-up. During            Figure 2: Joint angle of the hip, knee and ankle at different
the test, the subject maintained a constant velocity of            positions through the step cycle.
20mile/hr without the handles, and was instructed to pedal at
three different pedal positions. Subjects were tested with
their own comfortable shoes. After gathering data, the
subjects cooled down and rested.
Comparisons of parameters across position were made with
single factor ANOVA. The level of significance used in this
study was p ≤ 0.05.

RESULTS AND DISCUSSION                                             Figure 3: EMG data during the positions of forefront, normal
Figure 1 represents the pattern of elliptical movement profile     and back (from the left to the right of upper pattern).
trajectory for each position throughout the pedaling motion
from the forefront (0°) to the forefront (360°). Three pedal       CONCLUSIONS
positions with identical stride length but different               In comparison with the different pedal positions, the more
vertical altitudes are equidistant.                                changes of joint angle occurred at the forefront position.
                                                                   Also, the magnitude of muscle activation was significantly
                                                                   higher. In addition, in this experiment we also fond that
                                                                   muscle activation would be greater in order to keep to
                                                                   posture. Lower limb motion that used handles resulted in
                                                                   smaller muscle activation than without handles, and the
          Figure 1: Elliptical movement trajectory                 sequences and magnitude were identical. Therefore, in this
                                                                   study we can see, different elliptical movement trajectories
In figure 2, at the beginning of the step cycle, the hip and       have different performance results in kinematics and
knee joints begun extension and the ankle joint maintained         biomechanics.
plantar flexor. At the upward movement phase (25%~50%),
the hip and knee joints reached full extension and began           REFERENCES
flexing throughout the pedaling cycle. The hip joint reached       1. Huilien, C. (2006). Unpublished master’s thesis, National
peak flexion after the knee joint reached full flexion                Taiwan University, Taipei, Taiwan.
approximately at the top of the path (75%). The movement           2. Jialing, L. (2004). Unpublished master’s thesis, Chaoyang
of the ankle joint into dorsi flexion was brought on by the           University of Technology, Taipei, Taiwan.
displacement of the pedal, with peak dorsi flexor occurring        3. Porcari Jp, Zedaker JM, NawerL, and Miller M. (1998)
similarly to the phase of the knee joint (75%).                       Medicine & Science in Sports & Exercise, 30, pS1.

								
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