• Biomedical Engineering Letters
• /
• v.8 no.4
• /
• pp.345-353
• /
• 2018

This study suggested a new EMG-signal-based evaluation method for knee rehabilitation that provides not only fragmentary information like muscle power but also in-depth information like muscle fatigue in the field of rehabilitation which it has not been applied to. In our experiment, nine healthy subjects performed straight leg raise exercises which are widely performed for knee rehabilitation. During the exercises, we recorded the joint angle of the leg and EMG signals from four prime movers of the leg: rectus femoris (RFM), vastus lateralis, vastus medialis, and biceps femoris (BFLH). We extracted two parameters to estimate muscle fatigue from the EMG signals, the zero-crossing rate (ZCR) and amplitude of muscle tension (AMT) that can quantitatively assess muscle fatigue from EMG signals. We found a decrease in the ZCR for the RFM and the BFLH in the muscle fatigue condition for most of the subjects. Also, we found increases in the AMT for the RFM and the BFLH. Based on the results, we quantitatively confirmed that in the state of muscle fatigue, the ZCR shows a decreasing trend whereas the AMT shows an increasing trend. Our results show that both the ZCR and AMT are useful parameters for characterizing the EMG signals in the muscle fatigue condition. In addition, our proposed methods are expected to be useful for developing a navigation system for knee rehabilitation exercises by evaluating the two parameters in two-dimensional parameter space.

• Journal of International Academy of Physical Therapy Research
• /
• v.4 no.1
• /
• pp.516-522
• /
• 2013

The purpose of this study is to analysis of muscle fatigue in the upper trapezius and splenius capitis muscles according to therapy table height variation. The subjects were consisted of 15 healthy adults(10 males, 5 females) who had no medical history of neurological and musculoskeletal problems. In experiment, wireless electrode EMG system was measured for each the upper trapezius and splenius capitis muscles during the treatment performed on table. the differences in the muscle fatigue was compared for 4 types of table height(-6cm, -3cm, 0, +3cm from elbow in $90^{\circ}$ flexion position). Muscle fatigue according to therapy table height were significant difference except for left upper trapezius. And muscle fatigue of right upper trapezius and splenius capitis showed significant decrease in +3cm table height compared to -6cm table height(p<.05). Muscle fatigue of right upper trapezius and splenius capitis were the highest in -6cm table height, but those were the lowest in +3cm table height. This study propose to change therapy table height higher than +3cm from elbow in $90^{\circ}$ flexion position, if you hope to reduce muscle fatigue.

• 제어로봇시스템학회:학술대회논문집
• /
• 1998.10a
• /
• pp.352-355
• /
• 1998

A musculotendon model is investigated to show muscle fatigue under the repeated functional electrical stimulation (FES). The normalized Hill-type model can predict the decline in muscle force. It consists of nonlinear activation and contraction dynamics including physiological concepts of muscle fatigue. A muscle fatigue as a function of the intracellular acidification, pHi is inserted into contraction dynamics to estimate the force decline. The computer simulation shows that muscle force declines in stimulation time and the change in the estimate of the optimal fiber length has an effect only on muscle time constant not on the steady-state tetanic force.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.11
• /
• pp.4418-4426
• /
• 2010

Muscle fatigue often induces deterioration of postural balance and muscle contraction, such as strength or maximal voluntary contraction(MVC). This study was to investigate the effects of transcutaneous electrical stimulation(TENS) applied to the fatigued muscles on postural imbalance and decline in muscle strength following fatigue of triceps surae. For the 4 months from March, 2010, twenty healthy subjects without vestibular disease and visual disturbance were recruited and induced muscle fatigue of triceps surea performed by repeated voluntary contraction. TENS was applied to gastocnemius immediately after development of muscle fatigue. Postural sway length, velocity and MVC were recorded under these conditions: pre-fatigue, post-fatigue, and TENS application to fatigued muscle during post-fatigue. Muscle fatigue increased postural imbalance as expressed by sway length and velocity and decreased muscle contraction(p<.05), while TENS improved the postural imbalance and MVC following muscle fatigue during stance(p<.05). The results suggested that fatigue on plantar flexor is associated with postural balance and muscle contraction, and TENS application to fatigued muscle was effective in improving postural imbalance and decline in muscle strength following muscle fatigue. TENS will be an effective method in exercise, working environment and daily life.

• Journal of the Korean Society of Physical Medicine
• /
• v.14 no.3
• /
• pp.127-133
• /
• 2019

PURPOSE: The aim of this study was to obtain detailed and quantified data concerning the effects of plantarflexor fatigue induced to the non-paretic side on muscle activities of the bilateral lower extremities during walking in chronic stroke patients. METHODS: In this study, chronic stroke patients were evaluated for six months after the onset of stroke. To induce the non-paretic plantarflexor fatigue, 20 chronic stroke patients were asked to perform their given fatigue affecting assignments, which were presented in a forced contraction fatigue test method, until the range of motion of the plantarflexor was reduced to less than 50%. The muscle activities of the rectus femoris, tibialis anterior and gastrocnemius in the paretic and non-paretic lower extremities were measured using a wireless surface EMG before and after muscle fatigue induction. RESULTS: The findings showed that after plantarflexor fatigue was induced on the non-paretic side, a significant decrease in muscle activities of the rectus femoris on the paretic side was noted (p<.05). The muscle activities of the tibialis anterior and gastrocnemius were also observed to decrease, but, these results were not statistically significant (p>.05). In the non-paretic side, there was a significantly decrease in the muscle activities of the rectus femoris, tibialis anterior, and gastrocnemius (p<.05). CONCLUSION: These finding suggest that the muscle fatigue of the non-paretic plantarflexor affects not only the muscle activity of the ipsilateral lower extremity but also the muscles activity of the contralateral lower extremity. This highlights the necessity of performing exercise or training programs that do not cause muscle fatigue in clinical aspects.

• Fashion & Textile Research Journal
• /
• v.19 no.4
• /
• pp.504-514
• /
• 2017

Discomfort as well as muscular pain and musculoskeletal diseases occur in cases of stressed posture due to prolonged pressure. Therefore, the American Academy of Orthopaedic Surgeons (AAOS) and Pediatric Orthopaedic Society of North America (POSNA) recommend that bags that weigh no more than 15 - 20% of the wearer's weight. However, despite the prolonged pressure from using baby carriers, there are no recommendations and limited studies on how to protect wearers. Therefore, this study investigates subjective fatigue according to the usage of waist support and hip seat. Based on this, muscle fatigue and secondary subjective fatigue according to three types of currently commercial baby carriers (X-type, H-type, and H-hip type) were measured. Subjective comfortability was evaluated on a 5 point Likert-scale and subjective fatigue was evaluated on Borg's CR-10 scale. Objective muscle fatigue was also compared by measuring and analyzing electromyogram (EMG). The results of primary subjective fatigue showed statistically significant changes in the shoulders, waist, calves, and soles of the feet according to the usage of hip seats and waist support. Electromyogram measurements also showed less muscle fatigue at the upper trapezius muscle and thoracic erector spine muscle for the H-hip seat baby carrier, which has both waist support and hip seat, compared to an X-type baby carrier, which has neither. However, results of subjective fatigue showed opposite results at the waist despite having same results at the shoulders and beneath the shoulders. This show discrepancies between objective muscle fatigue and subjective fatigue; therefore, that both aspects must be taken into consideration when developing ergonomic baby carriers.

• The Journal of Korean Physical Therapy
• /
• v.26 no.2
• /
• pp.62-67
• /
• 2014

Purpose: The purpose of this study was to investigate tibialis anterior muscle fatigue through a Nordic walking when using pole. Methods: This study subject was 38 people who were twenties and randomly assigned to a control group with standard walking and Nordic walking group with Nordic walking. All subjects examined muscle fatigue with surface EMG and visual analogue scale for fatigue. The data were analyzed with SPSS window 18.0 program using ANCOVA. Results: The results were of a significant changes to the both tibialis anterior fatigue(p<0.01). The visual fatigue scales weren't significant difference. Conclusion: It was found that Dool-re-gil (Mt. Ji-Ri) was effective for muscle fatigue during walking, and it appears that it could be used clinically. So it is anticipated that improvement in clinical utilization for the people who's through a Nordic walking when using pole.

• Korean Journal of Acupuncture
• /
• v.29 no.4
• /
• pp.634-642
• /
• 2012

Objectives : The aim of the study is to find out whether effect of acupuncture is depending on the diameter of needle, which is a possible component of dose of acupuncture needling. Methods : To compare acupuncture effects in different diameters of needle, we measured the changes in muscle fatigue recovery using surface electromyogram(sEMG) in healthy 8 volunteers. Muscle fatigue was induced by 20 times sit-up for 1 min. Immediately after induction of muscle fatigue, acupuncture needle was inserted into ST36 or ST25 for 10 min by diameters of 0.20 mm, 0.30 mm, or 0.40 mm needles. The sEMG recording was followed by acupuncture for 30 min. As a control group, sEMG was recorded for the same period at rest after muscle fatigue induction. Results : In both of ST 36 and ST 25, stimulation with 0.4 mm diameter needle showed significant rapid recovery followed by short period of muscle fatigue increase. Stimulation with 0.2 mm diameter significantly suppressed the increase of muscle fatigue. Conclusions : These data suggest that acupuncture effect is, at least in part, dependent on diameter of needle. Therefore, diameter of needle is also considered to achieve effective outcome of acupuncture.

• PNF and Movement
• /
• v.17 no.3
• /
• pp.463-469
• /
• 2019

Purpose: This study investigated the effect of plantar-flexor muscle fatigue on the force sense and joint reposition sense of ankle joints in the healthy adults. Methods: Fifteen healthy subjects (male: 9, female: 6) participated in this study. A digital dynamometer was used to measure the force sense error while a wireless motion capture device was used to measure the joint reposition sense error. To induce plantar-flexor muscle fatigue for a dominant lower extremity, the subjects were asked to perform plantar flexion until exhaustion while barefoot. The differences in force sense error and joint reposition sense error for the ankle joint were measured immediately. The Wilcoxon test was used to compare these values before and after inducing plantar-flexor muscle fatigue. Results: The force sense error and joint reposition sense error of ankle joints after inducing plantar-flexor muscle fatigue increased significantly compared to the values before inducing muscle fatigue. Conclusion: This study suggests that plantar-flexor muscle fatigue could degrade the force sense and joint reposition sense in ankle joints. In addition, it could deteriorate ankle proprioception.

• PNF and Movement
• /
• v.16 no.3
• /
• pp.355-363
• /
• 2018

Purpose: The purpose of this study was to obtain detailed and quantified data concerning the effects of plantarflexor muscle fatigue induced in the non-paretic side on the spatial and temporal gait parameters of the bilateral lower extremities during walking in stroke patients. Methods: This study was conducted on 20 patients with chronic stroke. The load contraction fatigue test was applied to induce muscle fatigue in the non-paretic plantarflexor muscle. Step length, stride length, double support, gait velocity and cadence, and functional ambulatory profile (FAP) score in the bilateral lower extremities were measured using a gait analysis system in order to investigate changes in temporal and spatial gait parameters caused by muscle fatigue on the non-paretic side. The statistical significance of the results was evaluated using a paired t-test. Results: A review of the results for gait parameters revealed a significant increase in double support (p<0.05) and a significant decrease in step length, stride length, gait velocity and cadence, and FAP score (p<0.05). Conclusion: These results indicate that the muscle fatigue in the non-paretic side of the stroke patients also affected the paretic side, which led to a decrease in gait functions. This implies a necessity to perform exercise or training programs in a range of clinical aspects not causing muscle fatigue.