EMG analysis while using a smartphone

The purpose of this study was to clarify the influence of different postures on the activity of the shoulder girdle and lower back muscles while using a smartphone. Sixteen healthy male participants maintained two postures while using a smartphone : a good posture in which the tragus and acromion were closer to the vertical line passing through the greater trochanter, and a poor posture in which the tragus and acromion were farther from the vertical line passing through the greater trochanter. The target muscles were the rhomboid major (Rhom), upper trapezius, middle trapezius, lower trapezius (LT), lumbar erector spinae (LES), and lumbar multifidus (LMF). The activities of the Rhom and LT were significantly lower with poor posture than those with good posture. The activities of LES and LMF were significantly higher with poor posture than those with good posture. The results of this study indicated that poor posture was associated with hypoactivity of the shoulder girdle muscles and hyperactivity of the lower back muscles when compared with good posture. Poor posture for prolonged periods while using a smartphone would lead to malfunction of the shoulder girdle muscles and musculofascial lower back pain

EMG activity during 2000 m rowing

This study aimed to clarify the changes in the activity of the trunk and lower limb muscles during 2000-m rowing. Ten male rowers performed a 2000-m race simulation on a rowing ergometer. Electromyography results of the abdominal muscles, back muscles, gluteus maximus (GMax), biceps femoris (BF), and rectus femoris (RF) were recorded. The electromyographic activity during the three strokes after the start (initial stage), at 1000m (middle stage), and before the end (final stage) were analyzed. From the handle position, the rowing motion was divided into five phases (early-drive, middle-drive, late-drive, early-recovery, and late-recovery). The peak activities of the abdominal muscles, back muscles, GMax, and BF in each stroke of the rowing motion were delayed at the middle and final stages compared to the initial stage (P < 0.05). The peak activity of the RF was observed in the late-drive phase at the initial stage, whereas a high RF activity was observed in the middle-drive phase at the middle and final stages (P < 0.05). Considering the results of the activity of the back muscles and RF, RF muscular endurance enhancement may lead to a decrease in the load on the back muscles and help prevent muscular low back pain in rowers

movement self-screening scores and pain

Background : Various musculoskeletal screening and functional performance tests are used to evaluate physical condition. However, validated analysis tools that can identify gaps in pain knowledge during athletes’ daily training are lacking. This study aimed to investigate the relationship between pain intensity in athletes during their daily training and the KOJI AWARENESS™ test in order to determine whether body dysfunction is related to pain among athletes. Methods : This cross-sectional study was conducted in a fitness center at the authors’ affiliated institution. Thirty-five athletes (17 women and 18 men) aged 20-40 years were selected for study participation. KOJI AWARENESS™ self-evaluated test scores and pain intensity during daily training, as assessed on the numerical rating scale (NRS), were recorded. Results : The KOJI AWARENESS™ score showed a strong negative correlation with the NRS score for pain intensity during daily training (r = −0.640, P < 0.001). There was a significant negative correlation between KOJI AWARENESS™ and NRS scores, even when body mass index, sex, and age were entered as control variables. Conclusions : KOJI AWARENESS™ was highly accurate in detecting pain in athletes during their training

Effectiveness of KOJI AWARENESS tool

Background : The KOJI AWARENESS™ screening test is a self-administered screening tool for assessment of mobility, stability, and strength. It provides corrective exercises corresponding to the individual’s answers to the KOJI AWARENESS™ test questions. However, there is no evidence of the effectiveness of corrective exercises in improving KOJI AWARENESS™ screening test scores and activity-related pain. Methods : Twenty- six healthy subjects (11 female and 15 male ; age 20–50 years) were selected for participation. In a controlled laboratory setting, subjects were administered the KOJI AWARENESS™ test and were provided with individualized exercise programs based on the results of this first test. KOJI AWARENESS™ results were checked on the first day immediately after the first exercise session, and then again after the two-week program. Pain intensity was also assessed during daily training using a numerical rating scale. Results : Compared to pre-intervention, KOJI AWARENESS™ scores were significantly higher immediately after the first corrective exercise session and after 2 weeks of intervention (p < 0.001). Moreover, pain intensity was significantly lower after 2 weeks of intervention (p < 0.001). Conclusions : Individualized KOJI AWARENESS™ corrective exercises were effective immediately on the first day and also after the two-week program in improving the KOJI AWARENESS™ score and reducing pain intensity during daily training

Electromyographic and Kinematic Trunk Analysis of Boxing during a Dominate Straight Punch

The purpose of this study was to compare the surface electro myogram of trunk muscle activity and the three-dimensional kinematics of the trunk between experienced and novice boxers during straight punch with the rear arm. Fifteen university-age males participated in the study. Participants were ranked as experienced (n=8) or novice (n=7). The straight punch was broken into three phases as Preliminary Movements (PM), Thrown Punch (TP), and Returned Punch (RP). The surface electro myogram captured the activity of the rectus abdominis, external oblique, deltoid, and rectus femoris on the dominant side and the internal oblique-transversus abdominis (IO-TrA) and multifidus on both sides. Three-dimensional motion analysis was performed to calculate the horizontal angle of the Acromial line, the ASIS line and the Greater Trochanter of the femur (GT) line. Results of the surface electro myogram of the IO-TrA on the non-dominant side of the novice group during the PM phase were significantly higher than those of the experienced (p<0.05). Similarly, the IO-TrA of the dominant side of the novice during the TP phase were significantly higher than that of the experienced (p<0.05). In motion analysis, the ASIS line and the GT line were significantly greater in the experienced group compared with the novice (p<0.05). The novice group did not allow the entire trunk to rotate, but rather twisted the thoracolumbar vertebrae to throw the punch. Trunk rotation, not trunk twist, is important to the execution of the straight punch

The effect of dynamic stretching on hamstrings flexibility with respect to the spino-pelvic rhythm

Objectives : To ascertain the dynamic stretch effects of flexibility of the hamstrings on lumbar spine and pelvic kinematics. Background : Tight hamstrings are positively correlated with low back pain. However, it is unclear how flexibility of the hamstrings affects spino-pelvic rhythm. Methods : Twelve healthy men participated in the study. The straight leg raising (SLR) angle, finger floor distance (FFD), and spino-pelvic rhythm was measured before and after the 6-week stretching protocol. The forward bending task was divided into 4 phases. The paired t-test was used to determine significant differences before and after the FFD, SLR angle, lumbar motion, and pelvic motion, and spino-pelvic rhythm in each phase (p<0.05). Results : After 6 weeks of stretching, significant improvements were seen in the FFD with maximum forward bending and in the SLR angle. Total pelvic rotation was also significantly increased in contrast to total lumbar flexion. A decreased spino-pelvic ratio was seen in the final phase. Conclusion : Dynamic stretching could change the spino-pelvic rhythm to a pelvis-dominant motion, indicating that flexible hamstrings are important for preventing low back pain

Association analysis of ACE and ACTN3 in Elite Caucasian and East Asian Swimmers

PURPOSE: Polymorphic variation in the angiotensin-converting enzyme (ACE) and alpha-actinin-3 (ACTN3) genes has been reported to be associated with endurance and/or power-related human performance. Our aim was to investigate whether polymorphisms in ACE and ACTN3 are associated with elite swimmer status in Caucasian and East Asian populations. METHODS: ACE I/D and ACTN3 R577X genotyping was carried out for 200 elite Caucasian swimmers from European, Commonwealth, Russian and American cohorts (short and middle distance, SMD &le; 400 m, n = 130; long distance, LD&nbsp;greater than&nbsp;400 m, n = 70) and 326 elite Japanese and Taiwanese swimmers (short distance, SD &le; 100 m, n = 166; middle distance, MD: 200 - 400 m, n = 160). Genetic associations were evaluated by logistic regression and other tests accommodating multiple testing adjustment. RESULTS: ACE I/D was associated with swimmer status in Caucasians, with the D-allele being overrepresented in SMD swimmers under both additive and I-allele dominant models (permutation test p = 0.003 and p = 0.0005, respectively). ACE I/D was also associated with swimmer status in East Asians. In this group, however, the I-allele was overrepresented in the SD swimmer group (permutation test p = 0.041 and p = 0.0098 under the additive and the D-allele-dominant models, respectively). ACTN3 R577X was not significantly associated with swimmer status in either Caucasians or East Asians. CONCLUSIONS: ACE I/D associations were observed in these elite swimmer cohorts, with different risk alleles responsible for the associations in swimmers of different ethnicities. The functional ACTN3 R577X polymorphism did not show any significant association with elite swimmer status, despite numerous previous reports of associations with 'power/sprint' performance in other sports.Additional co-authors: Jason Gulbin, Viktor A. Rogozkin, Ildus I. Ahmetov, Nan Yang, Kathryn N. North, Saraslanidis Ploutarhos, Hugh E. Montgomery, Mark E.S. Bailey, and Yannis P. Pitsiladi