榎木 泰介

[Purpose] The present study aimed to demonstrate the following by using measurements for the definite angles provided by the digital protractor: inter-rater reliability and validity in radiograph measurements and smartphone application measurements. [Subjects and Methods] The subject angles were 26 angles between 15° and 180° that were selected randomly using a computer. Three examiners measured the angles using the radiograph and smartphone application. The radiograph was obtained at a position 250 cm from the chest shooting cassette holder. The smartphone photograph was obtained at positions 50, 100, 150, 200, and 250 cm from the holder. [Results] Under all conditions, intra-class correlation coefficients showed 0.999. The correlation coefficient was 0.999 for all conditions. The mean absolute difference to the protractor was ≤0.28° for all conditions. [Conclusion] In comparison with the protractor, radiograph measurements and smartphone application measurements, the results of the present study showed high inter-rater reliability, validity, and small error. The results indicated that radiograph and smartphone application measurements could be used as criteria of validity in angle measurements. It supported the legitimacy of high-quality previous studies that used radiograph measurements as a criterion for validity.

本研究は,大学体育会アメリカンフットボール部に所属する男子大学生70名を対象として,スポーツ活動における障害と外傷の発生について検討を行った。集計を行った2011年と2012年に発生した障害および外傷を対象に,発症の部位について,負傷者の属性(ポジション・学年)と調査年度による比較を行った。発症部位の分類は,1)頭・頚部,2)体幹(腹部・背部)および腰部,3)肩,4)腕および手・指部,5)大腿部,6)膝関節,7)下肢および足部である。調査対象の集団について,それぞれの身体組成を反映する所属ポジションから3群に分け,バックス群(B群),ミドル群(M群),ライン群(L群)とした。 集計を行った2年間における総受傷件数では,2011年と比較して2012年で2.2倍に増加した。1人当たりの平均受傷件数をみると,B群とL群において,2011年と比較して2012年で有意に高い値を示した。学年間の比較では,M群において高学年群が有意な高値を示した。受傷部位では,2012年に膝関節の負傷が増加しており,特にM群で顕著であった。 今回の対象集団では,2012年度において運動(練習・試合)の強度・頻度・時間が高まり,受傷件数が増加したと考えられる。そのような状況において増加する可能性のある受傷部位は,L群では脳震盪を含む頭・頚部,M群では前十字靱帯損傷を中心とした膝関節,B群では肩関節であった。これらのスポーツ障害および外傷を未然に防ぐには,テーピングや可動域を固定する装具などの活用,ポジションおよび競技固有の技能を支持する骨格筋群を中心としたトレーニング,学年や運動能力を考慮した練習強度と年間計画の設定などが重要である。This study investigated the occurrence of sports injuries and disorders in 70 students who belong to the collegiate American football team. We collected and surveyed a large number of sports injuries, trauma, failure and disorders occurred in 2011 and 2012. The case reports were divided into 7 groups according to following body sites, 1) head and neck, 2) body trunk(abdomen, lib and back), 3) shoulder joint, 4) arm, hand and finger, 5) femoral region, 6) knee joint, 7) lower leg and foot. These data were compared by the year, position in football and school grade. In addition, we set three groups from the position reflecting their body composition profile. There were bucks group(B), middle group(M), and lines group(L). The total number of injuries was increased to 2.2 times in 2012 compared to 2011. The average number of injuries per player, L and B group were significantly higher in 2012 compared to 2011. In the M group, the upper grades(senior and junior)showed a significant higher injury rate than lower grade(junior and freshmen). Moreover, M group had a tendency that injured risk of knee joint site was increased in 2012. It is considered that increased playing time, intensity and frequency in practices and games in 2012 had strong correlation with significantly increased number of injuries. Distinctive injuries related with the football position were 1) head and neck damages including a concussion in L group, 2) knee ligament damages in M group and 3) shoulder joint damages in B group. To forestall these sports injuries, utilize of the equipments and sports taping for fixing the range of motion, introduce the physical training, athletic rehabilitation and physiotherapy with a focus on the playing movement that supports for position-oriented football skills.

Purpose: To quantify the changes of hemoglobin mass (Hb(mass)) 1 and maximum oxygen consumption (VO2max) after 22 days training at 1300-1800 m combined with nightly exposure to 3000-m simulated altitude. We hypothesized that with simulated 3000-m altitude, an adequate beneficial dose could be as little as 10 h/24 h. Methods: Fourteen male collegiate runners were equally divided into 2 groups: altitude (ALT) and control (CON). Both groups spent 22 days at 1300-1800 m. ALT spent 10 h/night for 21 nights in simulated altitude (3000 m), and CON stayed at 1300 m. VO2max and Hb(mass) were measured twice before and once after the intervention. Blood was collected for assessment of percent reticulocytes (%retics), serum erythropoietin (EPO), ferritin, and soluble transferrin receptor (sTfR) concentrations. Results: Compared with CON there was an almost certain increase in absolute VO2max (8.6%, 90% confidence interval 4.8-12.6%) and a likely increase in absolute Hb(mass) (3.5%; 0.9-6.2%) at postintervention. The %retics were at least very likely higher in ALT than in CON throughout the 21 nights, and sTfR was also very likely higher in the ALT group until day 17. EPO of ALT was likely higher than that of CON on days 1 and 5 at altitude, whereas serum ferritin was likely lower in ALT than CON for most of the intervention. Conclusions: Together the combination of the natural and simulated altitude was a sufficient total dose of hypoxia to increase both Hb(mass) and VO2max.

本研究は,大学体育会アメリカンフットボール部に所属する男子大学生・32名を対象とし,身体組成と体力特性の関係について検討を行った。身体組成を反映する項目として,体重,体脂肪率,脂肪量,除脂肪体重,推定筋量を測定した。加えて,身体形態を示す指標として,身体6部位における周径囲を計測した。それらは,頚部,胸部,上腕部,前腕部,大腿部,下腿部の6部位である。また,体力特性を反映する指標として,6種目のパフォーマンステストを実施した。それらは,握力,背筋力,上体起こし,全身反応時間,ベンチプレス,40ヤード走である。まず,対象とした集団において,身体組成と体力特性の相関関係について,各測定項目間ごとに検討を行った。加えて,被験者をポジションに従い,バックス群(B群),ミドル群(M群),ライン群(L群)の3群に分け,それぞれの群について比較を行った。身体組成については,体重は体脂肪率だけではなく,推定骨格筋量とも有意な相関を示した。また,身体各部における周径囲については,全ての部位で体重,体脂肪率や除脂肪量と有意な相関を示した。一方,体力特性では,ベンチプレスと40ヤード走において,身体組成と有意な相関関係がみられた。これらの結果から,本研究で対象とした集団では,形態と関連する身体組成要素として,体重が重要な要因となる可能性が示唆された。一方で,体力特性をみると,握力,背筋力,上体起こしなどの基礎体力と,瞬時の運動神経反応については,体重や骨格筋量といった身体組成要因が,大きな影響を与えないことが示唆された。競技を行う上では,よりポジションに依存した特性をもつことが有効であることから,身体特性と体力特性の両面を評価しながら,ポジション特性を向上させることが重要だと考えられる。This study investigated the relationship between body composition and physical strength characteristics in collegiate American football players. We measured body weight, body fat percentage, body fat mass, lean body mass and muscle mass estimation as the indices reflect the body composition. In addition, the circumference at 6 sites of the body was measured as an indicator of the body form. Meanwhile, as an indicator that reflects the strength characteristics, we conducted a physical performance test of six events which were the grip strength, back strength, raise upper body, whole body reaction time, bench press and 40 yards run. In the results, body weight showed significant correlation with not only body fat percentage, but also with the estimated skeletal muscle mass. In the circumferential parts of the body showed a significant correlation with body weight, fat-free mass and body fat percentage in all 6 sites. On the other hand, in the physical characteristics which were bench press and 40 yards run, they showed significant correlations with body composition. On performing the competition in American football games, it is effective to acquire the more position-dependent characteristics. Therefore, it is important that while evaluating both sides of the strength characteristics and body composition characteristics to improve the position characteristics.

本研究は,大学体育会アメリカンフットボール部に所属する男子大学生を対象とし,競技におけるポジションの特性が,短時間高強度運動能力にどのような影響を及ぼすのかについて検討した。被験者32名をポジションに従って,バックス群(B群),ミドル群(M群),ライン群(L群)の3群に分け,身体組成の測定と運動負荷テストを実施し,それぞれの関連性について比較,検討を行った。 体重や体脂肪率など身体組成の項目では,L群が他の2群と比較して有意に高い値を示した。一方,運動負荷テストでは,3回の試技においてL群のみに顕著な低下がみられた。また,除脂肪体重と発揮パワーには相関関係があることが示された。The present study investigated the contributions of body composition to the ability of high intensity intermittent exercise in college American football players. According to the position, 32 subjects were divided into following 3 groups, bucks group (group B), middle group (group M), lines group (group L). We examined short period of time-intermittent exercise test and measurement of body composition of all subjects. We have found several characteristics of the position according to the body composition and the intermittent power output. In the body weight, body fat percentage, lean body weight and estimated muscle mass was significantly higher in group L compared with the other two groups. On the other hand, in the exercise test, the significant reduction was only observed in group L at the 3rd trial. In addition, there is a correlation in lean body weight and the intermittent power output.

We investigated the effects of nightly intermittent exposure to hypoxia and of training during intermittent hypoxia on both erythropoiesis and running economy (RE), which is indicated by the oxygen cost during running at submaximal speeds. Twenty-five college long-and middle-distance runners [maximal oxygen uptake (Vo(2max)) 60.3 +/- 4.7 ml.kg(-1).min(-1)] were randomly assigned to one of three groups: hypoxic residential group (HypR, 11 h/night at 3,000 m simulated altitude), hypoxic training group (HypT), or control group (Con), for an intervention of 29 nights. All subjects trained in Tokyo (altitude of 60 m) but HypT had additional high-intensity treadmill running for 30 min at 3,000 m simulated altitude on 12 days during the night intervention. Vo(2) was measured at standing rest during four submaximal speeds (12, 14, 16, and 18 km/h) and during a maximal stage to volitional exhaustion on a treadmill. Total hemoglobin mass (THb) was measured by carbon monoxide rebreathing. There were no significant changes in Vo(2max), THb, and the time to exhaustion in all three groups after the intervention. Nevertheless, HypR showed similar to 5% improvement of RE in normoxia (P < 0.01) after the intervention, reflected by reduced Vo(2) at 18 km/h and the decreased regression slope fitted to Vo(2) measured during rest position and the four submaximal speeds (P < 0.05), whereas no significant corresponding changes were found in HypT and Con. We concluded that our dose of intermittent hypoxia (3,000 m for similar to 11 h/night for 29 nights) was insufficient to enhance erythropoiesis or Vo(2max), but improved the RE at race speed of college runners.

We have examined the effects of administration of testosterone for 7 days on monocarboxylate transporter (MCT) 1 and MCT4 mRNAs and proteins in seven metabolically heterogeneous rat hindlimb muscles and in the heart. In addition, we also examined the effects of testosterone treatment on plasmalemmal MCT1 and MCT4, and lactate transport into giant sarcolemmal vesicles prepared from red and white hindlimb muscles and the heart. Testosterone did not alter MCT1 or MCT4 mRNA, except in the plantaris muscle. Testosterone increased MCT1 (20%-77%, P < 0.05) and MCT4 protein (29%-110%, P < 0.05) in five out of seven muscles examined. In contrast, in the heart MCT1 protein was not increased (P > 0.05), and MCT 4 mRNA and protein were not detected. There was no correlation between the testosterone-induced increments in MCT1 and MCT4 proteins. Muscle fibre composition was not associated with testosterone-induced increments in MCT1 protein. In contrast, there was a strong positive relationship between the testosterone-induced increments in MCT4 protein and the fast-twitch fibre composition of rat muscles. Lactate transport into giant sarcolemmal vesicles was increased in red (23%, P < 0.05) and white muscles (21%, P < 0.05), and in the heart (58%, P < 0.05) of testosterone-treated animals (P < 0.05). However, plasmalemmal MCT1 protein (red, +40%, P < 0.05; white, +39%, P < 0.05) and plasmalemmal MCT4 protein (red, +25%, P < 0.05; white, +48%, P < 0.05) were increased only in skeletal muscle. In the heart, plasmalemmal MCT1 protein was reduced (-20%, P < 0.05). In conclusion, these studies have shown that testosterone induces an increase in both MCT1 and MCT4 proteins and their plasmalemmal content in skeletal muscle. However, the testosterone-induced effect was tissue-specific, as MCT1 protein expression was not altered in the heart. In the heart, the testosterone-induced increase in lactate transport cannot be explained by changes in plasmalemmal MCT1 content, but in skeletal muscle the increase in the rate of lactate transport was associated with increases in plasmalemmal MCT1 and MCT4.

We examined whether the quantity of exercise performed influences the expression of monocarboxylate transporter (MCT) 1 and MCT4 in mouse skeletal muscles (plantaris, tibialis anterior, soleus) and heart. Wheel running exercise (1, 3, and 6 wk) was used, which results in marked variations in self-selected running activity. Differences in muscle MCT1 and MCT4 among animals, before the initiation of running, were not related to the quantity of exercise performed on the first day of wheel running. No changes in MCT4 were observed over the Course of the study (P > 0.05). After 6 wk of running, were there significant increases in heart (50%; P < 0.05) and muscle MCT1 (31-60%; P < 0.05) but not after I and 3 wk (P > 0.05). Because skeletal muscle MCT1 and running distances varied considerably, we examined the relationship between these two parameters. Within the first week of training, MCTI was negatively correlated with the accumulated running distance (r = -0.70, P < 0.05). On further analysis, it appears that, in the first week, excessive running (>20 km/wk) represses MCTI (-16.1%; P < 0.05), whereas more modest amounts of running (<20 km/wk) increase MCTI (+37%; P < 0.05). After 3 wk of running, a positive relationship was observed between MCTI and running distance (r = +0.76), although there is a threshold that must be exceeded before an increase over the control animals occurs. Finally, in week 6, when MCTI was increased in the tibialis anterior and plantaris muscles, there were no correlations with the accumulated running distances. These studies have shown that mild exercise training fails to increase MCT4 and that changes in MCT1 are complex, depending not only the accumulated exercise but also on the stage of training.

We compared the changes in monocarboxylate transporter 1 ( MCT1) and 4 (MCT4) proteins in heart and skeletal muscles in sedentary control and streptozotocin (STZ)-induced diabetic rats ( 3 wk) and in trained ( 3 wk) control and STZ-induced diabetic animals. In nondiabetic animals, training increased MCT1 in the plantaris (+51%; P < 0.01) but not in the soleus (+9%) or the heart (+14%). MCT4 was increased in the plantaris (+ 48%; P < 0.01) but not in the soleus muscles of trained nondiabetic animals. In sedentary diabetic animals, MCT1 was reduced in the heart ( - 30%), and in the plantaris ( - 31%; P < 0.01) and soleus ( - 26%) muscles. MCT4 content was also reduced in sedentary diabetic animals in the plantaris ( - 52%; P < 0.01) and soleus ( - 25%) muscles. In contrast, in trained diabetic animals, MCT1 and MCT4 in heart and/or muscle were similar to those of sedentary, nondiabetic animals ( P > 0.05) but were markedly greater than in the sedentary diabetic animals [ MCT1: plantaris +63%, soleus +51%, heart +51% ( P > 0.05); MCT4: plantaris +107%, soleus +17% ( P > 0.05)]. These studies have shown that 1) with STZ-induced diabetes, MCT1 and MCT4 are reduced in skeletal muscle and/or the heart and 2) exercise training alleviated these diabetes-induced reductions.