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The kick-start technique in competitive swimming generates a force acting on the starting platform owing to gravity, muscle contraction and resulting joint torque. To understand optimal body movement on the starting platform for maximising take-off velocity, it is necessary to investigate the joint torque in relation to the joint's rotation effects. Joint torques were calculated by inverse dynamics using kinetic and kinematic data. A one-way ANOVA showed significantly greater extensional torque for shoulders than for elbows or wrists, and for hips than for knees or ankles. The results indicated that the force of the hands was mainly influenced by extension torque at the shoulder joint. Hip joint extension torque on the front side lower limb (FSLL) was mainly used for supporting the body weight until hands off. After hands off, the front-foot force originated mainly by increases in ankle joint plantar flexion and knee joint extension torque on the FSLL. Rear side lower limb torque increases in the hip, knee and ankle joints provided the rear-foot force. This investigation clarified the magnitudes and functions of each joint torque acting on the extremities during the kick-start, providing practical information for improving starting performance.

Single-balloon enteroscopy-assisted endoscopic retrograde cholangiopancreatography (SBE-ERCP) has been increasingly performed for the treatment of malignant biliary obstruction (MBO) in patients with surgically altered anatomy (SAA), however evidence is scarce. Therefore, we conducted this study to evaluate the efficacy and safety of self-expandable metallic stent (SEMS) placement using a short type SBE.We retrospectively examined consecutive patients with SAA who received initial SEMS for MBO at our institution between February 2016 and February 2019. We evaluated patient characteristics, technical and functional success rates, time to recurrent biliary obstruction (TRBO) and complications according to the location of the biliary stricture.A total of 26 patients were included in this study. The primary tumor was gastric cancer in 12, pancreatic cancer in 6, cholangiocarcinoma in 6 and gallbladder cancer in 2. The biliary stricture site was distal bile duct in 14, hilar bile duct in 3 and hepaticojejunostomy (HJ) anastomosis in 9. Technical and functional success rates were 92 and 88%, respectively. TRBO, median survival time, overall rate of RBO and early complications were not different according to the stricture site (SEMS placement

This study investigated the deceleration effect of flutter kicking after dolphin kicking before commencing the stroke at swimmer's emersion. Eight male competitive swimmers (age 19.6 ± 1.2 years; Fédération Internationale de Natation points 733.6 ± 57.5) performed 15 m front crawl sprints from wall push-off three times in a row, with two types of underwater kicks [dolphin kick only (dolphin condition) and dolphin kick followed by flutter kick (dolphin-flutter condition)]. Sprint bouts were divided into four phases. Phases 1 and 2 were defined, respectively, as the fourth and fifth dolphin kicks. Phase 3 was defined as the first stroke (dolphin condition) and six beats of the flutter kicking (dolphin-flutter condition). Phase 4 was defined as the second stroke (dolphin condition) and the first stroke (dolphin-flutter condition). Two-way repeated measured analysis of variance on mean swimming velocities demonstrated an interaction of condition and phase (p 0.001) and a simple main effect (p 0.001) at Phase 3. These results indicated greater deceleration due to adding the flutter kick after the dolphin kick before commencing the stroke. Swimmers should use only the underwater dolphin kick before commencing the front crawl in start and turn segments.

The purpose of this study was to clarify factors to perform the hole-entry technique in the backstroke start. A total of 16 well-trained Japanese competitive swimmers were divided into two groups (backstroke specialists and non-specialists) to compare their backstroke start motions. Their backstroke motions were videotaped, and two-dimensional co-ordinates for the swimmers were obtained from the video images using direct linear transformation methods. A non-paired t-test and Mann-Whitney U-test were used to analyse the statistical difference of the kinematic variables between the groups. Backstroke specialists showed a significantly shorter 5 m time (P = 0.009, effect size = -1.54), a significantly higher position of the toe (P = 0.010, effect size = 1.47) at signal and of the hip at toe-off (P = 0.002, effect size = 1.94), a significantly larger hip joint angle at toe-off (P = 0.007, effect size = 1.60) and a significantly higher angular velocities of the hip joints (45-85%; P0.05) for the normalised time as compared to that of non-specialists. An earlier initiation of the extension and the maintenance of a higher extension speed at the hip joints were important factors in achieving an arched-back posture, which facilitated and water entrance with a small entry range.

The purpose of the study was to determine the extent to which differences in initial speed persist to the stroke phase in front-crawl swimming. Ten male college swimmers performed trials for three types of start that produced different initial speeds: maximal-effort dive, submaximal-effort dive, and maximal-effort wall push. The submaximal effort was determined by the swimmer himself. Participants swam 25 m for each trial, and their motions were recorded by five fixed cameras positioned lateral to the direction of swimming. The horizontal velocity of the greater trochanter of the femur was used to define swimming speed. Mean swimming speed, evaluated from the initial-speed phase to the stroke phase, differed across trials. The effect sizes of the initial-speed phase were 3.15 between maximal-effort dive and submaximal-effort dive (P0.001), 5.00 between maximal-effort dive and maximal-effort wall push (P0.001), and 2.71 between submaximal-effort dive and maximal-effort wall push (P0.001). However, differences in speed at the stroke phase were small (maximal-effort dive: 1.91 +/- 0.07 m . s(-1); submaximal-effort dive: 1.88 +/- 0.06 m . s(-1); maximal-effort wall push: 1.88 +/- 0.07 m . s(-1)), indicating that differences in initial speed do not persist to the stroke phase in front-crawl swimming.

We report the case of a 30-year-old Japanese woman with anorexia nervosa and vertebral fractures who was treated with etidronate. She had a history of anorexia nervosa, chronic back pain, osteoporosis, and multiple vertebral fractures (morphometric fractures) that responded poorly to treatment with alfacalcidol (1 μg daily) for 1 year and was treated with cyclical etidronate (200 mg for 2 weeks every 3 months) for 7 years. The lumbar spine bone mineral density (BMD) increased, and the serum alkaline phosphatase and urinary cross-linked N-terminal telopeptides of type I collagen levels and back pain decreased. During the 7-year period of treatment with etidronate, no osteoporotic fractures occurred. The patient experienced neither renal dysfunction nor hyperparathyroidism caused by osteomalacia. No gastrointestinal tract symptoms were observed. Thus, etidronate was effective for increasing the lumbar spine BMD and reducing back pain over a 7-year period without causing either osteoporotic fractures or adverse events.

Jun Iwamoto1, Yoshihiro Sato2, Tsuyoshi Takeda1, Hideo Matsumoto11Institute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, Japan; 2Department of Neurology, Mitate Hospital, Fukuoka, JapanAbstract: The purpose of the study was to confirm the short-term outcome of conservative treatment in terms of the ability to return to play and factors influencing return to play in athletes with symptomatic lumbar disc herniation. A total of 100 consecutive athletes (72 male and 28 female) who consulted our sports medicine clinic during the 16-year period between September 1993 and October 2009 because of severe low back pain and/or leg pain/numbness due to lumbar disc herniation were studied. The mean age of the subjects was 23 years. All of them were conservatively treated by being advised to discontinue their sporting activities with/without short-term medication. After the subjective symptoms had reduced by more than 80%, individual training was started in order to allow the athletes to return to play. Seventy-nine athletes (79.0%) returned to play at an average of 4.8 months (range 1–12 months) after the start of treatment and were able to sustain the activities for at least 6 months, the minimum duration of follow-up in the study. The outcome of the conservative treatment was not influenced by the intensity of the sporting activity. Multiple logistic regression analyses showed that the severity of the symptoms prior to the start of treatment was the factor influencing the ability of the athletes to return to play. The present study confirmed the satisfactory short-term outcome of conservative treatment in athletes with symptomatic lumbar disc herniation regarding return to play and revealed that subjective symptoms prior to the start of treatment appeared to be a key factor in return to play after conservative treatment.Keywords: lumbar disc herniation, athletes, return to play, conservative treatment, sciatica, low back pain

Jun Iwamoto1, Atsushi Miyata2, Yoshihiro Sato3, Tsuyoshi Takeda1, Hideo Matsumoto11Institute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, Japan; 2Department of Internal Medicine, Yahata Clinic, Tokyo, Japan; 3Department of Neurology, Mitate Hospital, Fukuoka, JapanAbstract: A retrospective study was conducted to evaluate the outcome of treatment with alendronate (ALN) for 5 years in postmenopausal Japanese women with an increased risk of fractures. Forty postmenopausal Japanese women with osteoporosis or osteopenia and clinical risk factors for fractures (mean age: 75.4 years) were analyzed; 33 patients were treated with alendronate and 7 were treated with alfacalcidol (ALF, controls) in an outpatient clinic run by general practitioners. The metacarpal bone mineral density (BMD) measured using a computed X-ray densitometer, urinary levels of cross-linked N-terminal telopeptides of type I collagen (NTX), and serum levels of alkaline phosphatase (ALP) were monitored during the 5-year treatment period. The urinary NTX and serum ALP levels decreased significantly in the ALN group, compared with the ALF group. The metacarpal BMD was sustained in the ALN group but decreased significantly in the ALF group; the difference between these two groups was also significant. The present study evaluated the outcome of treatment with ALN for 5 years in postmenopausal Japanese women with osteoporosis or osteopenia and clinical risk factors for fractures. ALN successfully suppressed bone turnover and sustained the metacarpal BMD over the 5-year period of treatment in postmenopausal Japanese women with an increased risk of fractures.Keywords: alendronate, osteoporosis, osteopenia, risk factors for fractures, postmenopausal women