Analysis of muscle activations in lower extremities muscles at various angles of ankle flexion using wedges during static squat exercise

[Purpose] This study aimed to investigate changes in activation of the rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius muscles during one-legged squats performed at various angles of ankle flexion. With the use of wedges, the muscles were activated at different angles of ankle flexion angles to establish the appropriate posture necessary for muscle strengthening and rehabilitation. [Subjects and Methods] Healthy adults aged 20–40 years were recruited from Good Morning Hospital in Ulsan City. Of the 22 participants, two dropped out during the tests, leaving a final sample of 20 participants. The wedges were 100 mm wide and 200 mm long and had inclinations of 10°, 30°, and 50°. EMG Analyzer software was used to measure muscle activation. [Results] A significant difference in the activation of the rectus femoris muscle at various angles of ankle flexion was seen. The gastrocnemius muscle exhibited significant differences in activation among the 0°–30°, 0°–50°, and 10°–50° inclinations. [Conclusion] Wedge-assisted muscle activation under different ankle flexion angles can be introduced as an effective exercise option under clinical conditions.Key words: Strengthening, Rehabilitation, One-leg squats     

Young’s moduli of subcutaneous tissues and muscles under different loads at the gluteal region calculated using ultrasonography

[Purpose] Young’s modulus distributions for subcutaneous and muscle tissues in a large sample of healthy individuals, based on ultrasonography and compression testing, remains uninvestigated till date. This study aimed to separately estimate the hardness of subcutaneous tissues and muscles in the human gluteal region under a range of loads in terms of mean Young’s moduli and associated distributions. [Participants and Methods] Data of 21 males aged 20–22 years were acquired using synchronous compression testing and ultrasonography. Stress-strain curves comprised the loads applied (stress) were plotted against ultrasonographic changes in subcutaneous/muscle tissue thickness (strain). Young’s moduli were calculated as slopes of approximation curves fitted to highly linear regions of the stress-strain curves. [Results] Young’s moduli (mean ± standard deviation) for gluteal subcutaneous and muscle tissues were estimated as: 26.1 ± 19.0 kPa, 1-N load; 2,199.1 ± 1,354.8 kPa, 30-N load; and 62.2 ± 10.3 kPa, 5-N load; 440.4 ± 80.0 kPa, 30-N load, respectively. No correlation between any pair of these measures reached statistical significance. [Conclusion] Young’s moduli were successfully measured for subcutaneous and muscle tissues in a large participant sample using ultrasonography and compression testing. Our results may serve as reference data when assessing tissue hardness by palpation.     

The Effect of Shoulder Flexion Angles on the Recruitment of Upper-extremity Muscles during Isometric Contraction

The purpose of this study was to investigate the differences in muscle activation patterns of the biceps brachii (BB) and flexor carpi radialis (FCR) muscles, while measuring the resultant force (RF) at different shoulder flexion angles. [Subjects] Thirteen healthy males (age 24.85±3.4 years, weight; 77.8±7.9 kg; height, 1.7±0.05 m) were enrolled in this study. [Methods] The resultant force was measured by a force transducer . The elbow angle remained constant and the flexion shoulder angle was changed (30°, 45°, 60°, 75° and 90°). [Results] The results of the surface EMG show the largest muscle activities occurred at a shoulder flexion of 75° for BB and 90° for FCR. The largest resultant force was measured at a shoulder flexion angle of 75°. We conclude, that when performing the biceps curl exercise using an arm curl machine, the shoulder should be flexed at 75° to maximize the focus of the exercise for the BB. [Conclusion] These results are useful from the perspective of design as they highlight the differences in the muscle activation of BB and FCR with postural change. Ultimately this knowledge can be used in the design of rehabilitation training for the shoulder as they show that posture can affect muscle activation.     

Effects of specific muscle imbalance improvement training on the balance ability in elite fencers

[Purpose] The lunge Motion that occurs frequently in fencing training and matches results in imbalance of the upper and lower limbs muscles. This research focuses on the improvement of the imbalance that occurs in the national team fencers of the Republic of Korea through specific muscle imbalance improvement training. [Subjects] The subjects of this research were limited to right-handed male fencers. Nine male, right-handed national fencing athletes were selected for this study (4 epee, 5 sabre; age 28.2 ± 2.2 years; height 182.3 ± 4.0 cm; weight 76.5 ± 8.2 kg; experience 12.4 ± 3.0 years). [Methods] The specific muscle imbalance improvement training program was performed for 12 weeks and Pre-Post tests were to evaluate its effect on the experimental group. Measurements comprised anthropometry, test of balance, and movement analysis. [Results] After the training program, mediolateral sway of the nondominant lower limb and the balance scale showed statistically significant improvement. [Conclusion] The specific muscle imbalance improvement training program used in this research was proven to be effective for improving the muscle imbalance of elite fencers.Key words: Fencing, Muscle imbalance, Training     

The Effects of Wearing High Heels while Pressing a Car Accelerator Pedal on Lower Extremity Muscle Activation

[Purpose] The purpose of this study was to determine the effects of wearing high heels while driving on lower extremity muscle activation. [Subjects] The subjects of this experimental study were 14 healthy women in their 20s who normally wear shoes with high heels. [Methods] The subjects were asked to place their shoes on an accelerator pedal with the heel touching the floor and then asked to press the pedal with as much pressure as possible for 3 seconds before removing their feet from the pedal. A total of 3 measurements were taken for each heel height (flat, 5 cm, 7 cm), and the heel height was randomly selected. [Results] The levels of muscle activity, indicated as the percentage of reference voluntary contraction, for gastrocnemius muscle in the flat, 5 cm, and 7 cm shoes were 180.8±61.8%, 285.4±122.3%, and 366.2±193.7%, respectively, and there were significant differences between groups. Those for the soleus muscle were 477.3±209.2%, 718.8±380.5%, and 882.4±509.9%, and there were significant differences between groups. [Conclusion] To summarize the results of this study, it was found that female drivers require greater lower extremity muscle activation when wearing high heels than when wearing low heels. Furthermore, instability and muscle fatigue of the ankle joint, which results from wearing high heels on a daily basis, could also occur while driving.Key words: High heel, Muscle activation, Car accelerator pedal     

Sex differences in knee strength deficit 1?year after anterior cruciate ligament reconstruction

[Purpose] Little is known about the outcome differences between men and women after anterior cruciate ligament (ACL) reconstruction. Therefore, the present study aimed to compare knee muscle strength between men and women 1 year after ACL reconstruction. [Subjects and Methods] Retrospective and outcome study. Between 2012 and 2015, 35 males (mean age, 29.7 ± 010.7 years) and 35 females (mean age, 28.2 ± 11.3 years) who had undergone primary ACL reconstruction were recruited from Samsung medical centers. We assessed the strength deficit in the quadriceps (extensor) and hamstrings (flexor) at 60°/sec and 180°/sec with isokinetic testing equipment. Statistical analysis was conducted with a t-test to determine if sex differences existed in knee strength deficit. [Results] Significant differences were noted between men and women with respect to extensor muscle strength deficit. Women reported less extensor muscle strength than men did, at the angular velocities 60°/sec and 180°/sec. However, no significant sex differences were found at either velocity with respect to the strength deficit of the knee flexor muscles. [Conclusion] Compared to male patients, female patients reported significantly less extensor muscle strength and less improvement 1 year after reconstruction.Key words: Anterior cruciate ligament, Sex, Female     

Elucidation of abductor digiti minimi activity in chronic ankle instability

[Purpose] This study aimed to compare the muscle activity around the foot and ankle joints, notably of the abductor digiti minimi, between affected and unaffected sides of individuals with chronic ankle instability. [Participants and Methods] Twelve adult males with chronic ankle instability in one ankle (age, 27.7 ± 5.4 years; height, 172.5 ± 8.1 cm; weight, 67.5 ± 8.1 kg) were included and underwent surface electromyography assessments in multiple positions on both affected and unaffected sides. Measurements were obtained for eight muscles including the abductor digiti minimi. Each measurement included a 5-s segment of the stable waveform, with the root mean square-processed and normalized to the resting position set to 1. [Results] Abductor digiti minimi activity on the affected side was significantly reduced during maximal toe extension/abduction with both ankle dorsiflexion and plantarflexion. Peroneus longus activity on the affected side was significantly greater during maximal toe extension/abduction with ankle plantarflexion; peroneus longus and tibialis anterior muscle activities were significantly greater on the affected side during maximal toe extension/abduction with ankle dorsiflexion. [Conclusion] In the absence of load, muscle imbalance in the intrinsic and extrinsic muscles of the foot was suggested. However, no significant differences were observed under loading conditions.     

The Usefulness of Performance Matrix Tests in Locomotor System Evaluation of Girls Attending a Ballet School — Preliminary Observation

[Purpose] Learning ballet is connected with continuous use of the locomotor system while subjecting it to high loads. Therefore, we conducted some research defining the appearance of weak links in the motor system, in order to eliminate the risk of injury. [Methods] Fifty-two female students of a ballet school were examined. To identify weak links, low-threshold Performance Matrix tests were performed. An analysis of weak link occurrence in the locomotor system was carried out, using two way analysis of variance ANOVA Tukey’s HSD test, clustering methods and Principal Component Analysis (PCA). [Results] The average age of the subjects was 11.64±0.53 years (mean ± standard deviation), their average body height was 151.1±7.5 cm, their average body weight was 35.92±5.41 kg, and their average time of learning at ballet school was 2.17±0.65 years. We found that there were significant differences in weak links occurrence in the motor system of every girl examined. [Conclusions] Weak links were found in every location of the motor system. Our results show that the influence of weak link location is essentially different from their occurrence, and that learning ballet has a significantly different impact on the number of weak links in different locations.Key words: Ballet, Injuries, Performance Matrix tests     

Association between height-corrected appendicular and regional skeletal muscle mass and insulin resistance in patients with type 2 diabetes

[Purpose] The effect of height-corrected skeletal muscle masses on insulin resistance has not been fully investigated in patients with type 2 diabetes. In this study, we aimed to investigate the association between height-corrected appendicular and regional skeletal muscle masses and insulin resistance in patients with type 2 diabetes. [Participants and Methods] We included 136 male and 100 female patients with type 2 diabetes (average age, male 55.7 ± 12.3 years old, female 60.7 ± 11.3 years old, and average height, male 1.67 ± 0.06 m, female 1.54 ± 0.06 m) in this study. Bioelectrical impedance analysis was used to evaluate skeletal muscle mass. We calculated the appendicular skeletal muscle mass index by dividing the appendicular skeletal muscle mass by the square of the patient’s height. The upper limb muscle mass, lower limb muscle mass, and trunk muscle mass figures were also divided by the square of the patient’s height. We used the homeostasis model assessment of insulin resistance as a marker of insulin resistance. [Results] In multiple regression analysis, the homeostasis model assessment of insulin resistance was inversely associated with appendicular skeletal muscle mass index and lower limb muscle mass/height² in male patients with type 2 diabetes when adjusted for age and body mass index. Similarly, the homeostasis model assessment of insulin resistance was inversely associated with appendicular skeletal muscle mass index and lower limb muscle mass/height² in non-obese female patients with type 2 diabetes. [Conclusion] We have confirmed that there is an association between appendicular skeletal muscle mass index and lower limb muscle mass/height² with insulin resistance in male and female patients with type 2 diabetes, except in females with obesity.     

The use of a cold pack during resistance exercises is effective for reducing intramuscular oxygenation and increasing myoelectric activity

[Purpose] The purpose of this study was to determine the efficacy of using a cold pack while doing resistance exercises for enhancing muscle strength and muscle hypertrophy through decreased intramuscular oxygenation and/or increased myoelectric activity. [Participants and Methods] Twenty-four resistance-trained males (age: 26.4 ± 8.4 years, height: 169.3 ± 5.2 cm, body weight: 74.7 ± 8.8 kg) involved in this study. All the participants completed two experimental sessions in random order (cold pack resistance exercise and resistance exercise) with a 3-day interval. Four types of resistance exercises (4 sets × 8 repetitions with an 8-repetition maximum) targeting the right triceps brachii muscle were performed in both the experimental sessions. [Results] The percentage baseline oxyhemoglobin/myoglobin level during resistance exercise was significantly lower, the half-recovery time of muscle oxygenation in intervals between sets was significantly longer, and the myoelectric activity was significantly higher in the cold pack resistance exercise than in the resistance exercise session. [Conclusion] The results suggest that using a cold pack with resistance exercises is effective in inducing intramuscular deoxygenation and increasing myoelectric activity and may be useful for increasing muscle strength and inducing hypertrophy.     

The Influence of Short-term Aquatic Training on Obstacle Crossing in Gait by the Elderly

[Purpose] The purpose of this study was to examine the fall-prevention effect of 12 weeks of aquatic training for the elderly using variables representative of the relationship between the trailing foot and an obstacle. [Subjects] Ten healthy elderly participants, who lived in C city, (age: 77.15±5.21 yrs, height: 149.87±3.54 cm, body mass: 57.44 ±6.74, and BMI: 25.58±2.98 kg/m²), participated in this study. [Methods] To determine the effect of 12 weeks’ aquatic training, 3-D motion analysis with 7 infrared cameras and one force plate, was performed. [Results] TC, HC, MVHC, and CV significantly increased after intervention. For the all gait stability parameters, statistically significant training effects were found. [Conclusion] In conclusion, 12 weeks’ aquatic exercise can help the elderly become more stable when crossing a height obstacle, which is the most frequent cause of falls by the elderly.Key words: Obstacle-crossing in gait, The elderly fall, Elderly gait stability     

Whole-body vibration-induced muscular reflex: Is it a stretch-induced reflex?

[Purpose] Whole-body vibration (WBV) can induce reflex responses in muscles. A number of studies have reported that the physiological mechanisms underlying this type of reflex activity can be explained by reference to a stretch-induced reflex. Thus, the primary objective of this study was to test whether the WBV-induced muscular reflex (WBV-IMR) can be explained as a stretch-induced reflex. [Subjects and Methods] The present study assessed 20 healthy males using surface electrodes placed on their right soleus muscle. The latency of the tendon reflex (T-reflex) as a stretch-induced reflex was compared with the reflex latency of the WBV-IMR. In addition, simulations were performed at 25, 30, 35, 40, 45, and 50 Hz to determine the stretch frequency of the muscle during WBV. [Results] WBV-IMR latency (40.5 ± 0.8 ms; 95% confidence interval [CI]: 39.0–41.9 ms) was significantly longer than T-reflex latency (34.6 ± 0.5 ms; 95% CI: 33.6–35.5 ms) and the mean difference was 6.2 ms (95% CI of the difference: 4.7–7.7 ms). The simulations performed in the present study demonstrated that the frequency of the stretch signal would be twice the frequency of the vibration. [Conclusion] These findings do not support the notion that WBV-IMR can be explained by reference to a stretch-induced reflex.Key words: Skeletal muscle function, Gravitational physiology, Tonic vibration reflex     

Effects of yoga on the intervention of levator ani hiatus in postpartum women: a prospective study

[Purpose] This study aimed to explore the application value of yoga intervention in early postpartum recovery of the levator ani muscle hiatus (LAH) area. [Participants and Methods] Females in natural labor from May 2020 to November 2020 in the Third People’s Hospital of Sun Yat-sen University Ultrasound Research Center were prospectively included for a pelvic ultrasound examination. The control group received no intervention. The experimental group received 60-min yoga once a week from week 1 to week 12 postpartum. A pelvic ultrasound examination was performed on the week 6 and week 12 postpartum. The LAH area was measured at rest, during contraction and Valsalva maneuver. [Results] A total of 128 participants who met the inclusion criteria were selected and randomly assigned to the control group (n=66) and the experimental group (n=62) in pre and post intervention design. No significant differences were found in age, parity, body mass index, and fetal weight between the control and experimental groups. Further, no significant difference was observed in the LAH area between the control and experimental groups at rest, during contraction and Valsalva maneuver on the week 6 postpartum. However, the LAH area in experimental group significantly reduced at rest, during contraction and Valsalva maneuver on the week 12 postpartum. The differences of LAH area (date week 6 minus date week 12) in the control group at rest, during contraction and Valsalva maneuver were 0.12 ± 3.12 cm², 0.80 ± 2.29 cm², and 0.80 ± 4.22 cm², while in the control these were 1.95 ± 3.41 cm², 1.39 ± 1.91 cm², and 3.81 ± 5.49 cm², respectively. Compared with control group, the differences of LAH area significantly increased in experimental group at rest and during Valsalva maneuver. [Conclusion] Yoga intervention can help in the recovery of LAH.     

Effect of exercise at light loads with manipulative resistance on infraspinatus,trapezius (upper fiber) and deltoid (middle fiber) muscle activities in shoulder joint elevation

[Purpose] To clarify rotator cuff muscular activity in the raised position of the closed kinetic chain (CKC) exercise. [Subjects] Twenty-nine cases were studied, 19 men and 10 women (average age 21.5 ±4.7 years old, average body weight 60.1 kg ±11.4). [Methods] To determine the effects of the closed kinetic chain exercise on the upper limb, we measured the surface EMG of the infraspinatus muscle, the trapezius (upper fiber) and the deltoid (middle fiber) with the arm elevated. [Results] Our results show that at an elevation angle of 150° in the scapular plane of the upper limb, with 5% body weight load, the EMG activities of the infraspinatus muscle are approximately 30% of maximum voluntary contraction (MVC). [Conclusion] The raised position of the CKC exercise is effective in physical therapy for functional recovery of the infraspinatus muscle.Key words: Shoulder joint, IEMG, CKC     

Reliability of lower leg muscle thickness measurement along the long axis of the muscle using ultrasound imaging,in a sitting position

[Purpose] To verify the reliability and validity of lower leg muscle thickness (MT) assessment along the muscle’s long axis using ultrasound imaging (USI) in a sitting position. [Participants and Methods] Twenty healthy adult female participants (aged, 20.3 ± 0.9 years) were included in the study. Intra- and inter-examiner reliability of the proximal, middle, and distal MT of the tibialis anterior (TA) and medial head of the gastrocnemius (GM) were verified using USI in a sitting position. Additionally, the relationship between MT measurement using USI and muscle cross-sectional area (MCSA) measurement using magnetic resonance imaging (MRI), as well as the ankle joint’s maximum muscle strength, were examined. [Results] The reliability of TA and GM MT measurement using USI was high for all regions. The relationship between MCSA measurement using MRI and MT measurement using USI showed a significant correlation in all the regions for both muscles. The relationship between ankle muscle strength and USI of MT was not significantly correlated in any region for both muscles. [Conclusion] Measurement of MT using USI is reliable and valid for MCSA, but must be combined with assessments of other factors for muscle strength.     

The effects of t’ai chi on muscle activity,pain, and balance in females in their 20s with acute low back pain

[Purpose] This study was conducted in order to examine the effects of t’ai chi on females in their 20s with acute low back pain. The subjects were 30 females in their 20s with acute low back pain. [Subjects and Methods] They were equally and randomly divided into a t’ai chi group and a stretching group. The intervention was applied three times per week, one hour each time, for a total of eight weeks. During the one hour, the subjects conducted warm-up exercises for 10 min, primary exercises for 40 min, and cool-down exercises for 10 min. In order to examine changes in low back pain in the patients according to the intervention method, muscle activity, pain, and balance elements (left and right side movement distance, forward and backward movement distance) were measured. [Results] Muscle activity and the visual analog scale score significantly decreased in both the t’ai chi group and the stretching group. Regarding changes in balance elements, the t’ai chi group’s left and right side movement distance decreased, which was statistically significant. However, the t’ai chi group’s forward and backward movement distance and the stretching group’s forward and backward movement distance and left and right side movement distance did not change. [Conclusion] According to the results of this study, t’ai chi is considered an appropriate exercise program to reduce acute low back pain in females in their 20s. This is because when compared with stretching, it enables posture maintenance with lesser force due to decreased muscle activity, it is more helpful for improvements in balance ability, and it is effective in decreasing pain.Key words: T’ai chi, Low back pain     

What is the effect of peripheral muscle fatigue,pulmonary function,and body composition on functional exercise capacity in acromegalic patients?

[Purpose] The six-minute walk test (6MWT) is increasingly being used as an important tool for analyzing functional capacity in patients with multisystem disorders. The aim of this study was to evaluate the effect of body composition, peripheral muscle function, and pulmonary function on the six-minute walk distance (6MWD) in acromegalic patients. [Subjects and Methods] Thirty-two patients with active acromegaly, with a mean age of 48.6 ± 12.1 years, underwent an evaluation of body composition using electrical bioimpedance, isometric dynamometry with surface electromyography, tests of pulmonary function, and the 6MWT. [Results] The mean ± SD values for the 6MWD, fat-free mass (FFM), and maximal expiratory pressure (MEP) were 65.5 ± 11.7% predicted, 55.1 ± 10.6 kg, and 55.2 ± 16.8% predicted, respectively. There was a significant correlation between the 6MWD and the following parameters: the angle of the linear regression line obtained using the values of the median frequency electromyography signal over time during the fatigability test for the vastus medialis muscle (MDF, r=0.65), FFM (r=0.62), MEP (r=0.60), height⁽²⁾/resistance index (r=0.52), resistance (r=−0.50), and forced expiratory volume in 1 second (r=0.50). Multivariate analysis showed that MDF, FFM, and MEP were independent predictors of the 6MWD (R²=0.52). [Conclusion] The fatigability of the peripheral muscles, FFM, and MEP are the primary determinants of the 6MWD in acromegalics.Key words: Acromegaly, Muscle strength, Exercise     

Differences in understanding and subjective effects of home-visit rehabilitation between user families and rehabilitation providers

[Purpose] This study aimed to clarify differences in understanding and subjective effects of home-visit rehabilitation between user families and rehabilitation providers. [Subjects] The subjects were home-visit rehabilitation providers and user families. [Methods] Home-visit rehabilitation providers and user families completed a self-administered questionnaire regarding the content and subjective effects of home-visit rehabilitation. For statistical analysis, the McNemar’s test was used. [Results] Fifty pairs of responses met the inclusion criteria. The mean age of user families was 65.0 ± 11.2 years, and 58.0% (29/50) were spouses of users (user mean age, 77.7 ± 10.2 years; 48.0% (24/50) female). With regard to home-visit rehabilitation content, user families thought that paralysis improvement exercise, massage, and self-care activities were implemented to a greater degree than did rehabilitation providers. With regard to the subjective effects of home-visit rehabilitation, a higher proportion of user families noticed “maintenance/improvement” effects on symptoms and sequelae, as well as pain and suffering, compared with providers. [Conclusion] User families believed that rehabilitation would also improve users’ symptoms and pain. Care providers should explain the aims of home-visit rehabilitation to users and their families, both of which require a strong understanding of home-visit rehabilitation in order to achieve rehabilitation goals.Key words: Home-visit rehabilitation, Family’s subjective effects, Rehabilitation program     

Smartphone addiction and its association with upper body musculoskeletal symptoms among university students classified by age and gender

[Purpose] The purposes of this study were to: 1) survey smartphone addiction among university students, 2) survey the prevalence of upper body musculoskeletal symptoms in relation to the respondents’ sitting posture, and 3) determine the association between smartphone addiction and upper body musculoskeletal symptoms, classified by age and gender. [Participants and Methods] Two self-report questionnaires were employed to collect data from 2,645 university students in Chiang Mai, Thailand. [Results] Of 2,027 respondents (860 males and 1,167 females), the participants’ ages ranged from 18 to 26 years with a mean age of 20.5 ± 1.38 years. The prevalence of smartphone addiction and upper body musculoskeletal symptoms among participants were 15.9% and 30%, respectively. Overall, the mean value of pain severity was 3.66 ± 1.67 out of 10 on the visual analog scale. Multivariate logistic regression analysis revealed that smartphone addiction (OR=6.05, 95% CI: 4.68–7.84), was significantly associated with upper-body musculoskeletal symptoms when adjusted by age and gender. [Conclusion] The prevalence of upper body musculoskeletal symptoms was relatively high, especially for female smartphone users and students aged over 20 years. These results suggest that smartphone addiction may be a potential risk factor for upper body musculoskeletal symptoms in university students.Key words: Smartphone addiction, Musculoskeletal symptoms, University students     

Comparison of ankle plantar flexor activity between double-leg heel raise and walking

[Purpose] We aimed to evaluate the difference in the muscle activity between the double-leg heel raise (DHR) and treadmill walking. [Subjects] Thirty healthy males aged 21.5 ± 1.6 years (body mass 63.6 ± 9.3 kg, height 171.0 ± 4.5 cm) participated in the study. [Methods] Electromyograms were simultaneously recorded from both heads of the gastrocnemius and the soleus of the right side during the DHR and treadmill walking. The DHR conditions were maximum plantar flexion (MPF), 3/4 MPF, 2/4 MPF, and 1/4 MPF, and the walking speeds were 20, 40, 60, 80, and 100 m/min. [Results] The muscle activity during the DHR and walking significantly increased with increments in the height of the heel raise and walking speed, respectively. Comparison of the muscle activity at MPF with that at each walking speed revealed that the muscle activity in the soleus and gastrocnemius medial head during walking exceeded that during the DHR in less than 3.3% of cases. [Conclusion] The DHR test is useful for evaluating the ankle plantar flexor activity necessary for walking.Key words: Double-leg heel raise, Walking, Plantar flexor