成田健造(慶應義塾大学), 仙石泰雄(筑波大学)

本研究の目的は，競技レベルの異なる2名の泳者を対象に，背泳ぎの抵抗力と泳動作について調査することであった．対象者は背泳ぎを専門種目とし，日本代表経験を有する選手と，全国大会出場経験を有する選手の1名ずつであった．泳速度は1.20 m/s とし，実験は全て実験用回流水槽にて実施した．抵抗力はMRT法を用いて評価し，抵抗力を身体表面積で除して抵抗係数を算出した．泳動作は3次元モーションキャプチャシステムを用いて分析した．体幹の傾きを評価する指標として，第一胸椎棘突起と大転子の位置関係を評価し，手部の動作スピードは3次元方向と推進方向のそれぞれを分析した．結果として，抵抗力と抵抗係数の両方で競技レベルの高い泳者が大きな値を示したが，身体表面積で除した抵抗係数では両者の差が小さくなっており，体格の違いが背泳ぎでの抵抗力に影響したことが示唆された．泳動作について，ストローク頻度と手部の動作スピードでは競技力の低い泳者が高い値を示し，一方で体幹の傾きではわずかに競技力の高い泳者が高い値を示した．これらのことから，背泳ぎにおける抵抗力は，競技レベルが高い泳者の抵抗力が必ずしも低くなるわけではないことが示唆された．

Features of resistance force and swimming motions in the backstroke of a swimmer on Japan's national team and a swimmer who had competed in a national tournament: Hand movements and inclination of the trunk
The present study compared the resistance force and swimming motions of two swimmers who were at different competitive performance levels in events. Both swimmers specialized in the backstroke. One of them had been selected as a member of Japan’s national team; the other had participated in a national tournament. The study was conducted in an experimental circulating water flume at a swimming speed of 1.20 m/s. Resistance force was measured using MRT method; the resistance coefficient was calculated by dividing the resistance force by the surface area of the swimmer’s body. Swimming movements were analyzed with a three dimensional motion capture system. In order to determine the index of inclination of the trunk, the relationship between the position of the acantha of the first thoracic vertebra and the greater trochanter was analyzed. The speed of movement of the hands was measured in three dimensions and in the direction of propulsion. The results showed that the swimmer who was at a higher competitive level had higher values both in resistance force and resistance coefficient, although the difference between the two participants in the resistance coefficient divided by the surface area of the body was rather small. This suggests that the difference in the physical size of their bodies may have been reflected in the resistance force. Analysis of the data from the swimming movements showed that the swimmer who had lower competitive power made strokes more frequently and had faster hand movements, whereas the swimmer who had higher competitive power had a slightly higher inclination of the trunk of his body. These results suggest that the resistance force when swimming backstroke may not necessarily be less in swimmers who are at a higher competitive level.

中島大貴(中京大学), 桜井伸二(中京大学)

本研究の目的は，野球において超速球を見るトレーニングが打撃パフォーマンスに与える即時効果を明らかにすることであった．大学硬式野球部に所属する打者5名に，ピッチングマシンから約165km/hで投射される超速球を打席で見るトレーニングを15球×2セット行わせ，その前後に約150km/hで投球されるボールを10球打撃するパフォーマンス測定を行わせた．トレーニング前後の主観的な打撃感覚の変化を調べるためアンケート調査を行い，客観的なパフォーマンスの変化を調べるために高速度ビデオカメラで打撃動作を撮影した．その結果，全ての分析対象者が「トレーニング後は投球が遅く感じた」と回答した．また，個人差はみられたものの，その感覚は一定時間継続することが示唆された．さらに，トレーニング後では全ての分析対象者がより投手側でボールをインパクトしていた．一方で，トレーニング前後で空振りの割合に変化はなく，打撃の正確性は向上しなかった．そのため，打撃の正確性を向上させるためには普段から継続的に超速球を見る，あるいは打撃するトレーニングを行うことが重要であることが示唆された．

Effects of visual training with very fast balls on batting performance in baseball
The present study examined effects of visual training with balls pitched very fast on batting performance. The participants, 5 university baseball players, received training in which they stood in the batter’s box and looked at balls shot from a pitching machine at 165 km/h. The training was repeated with 15 balls in each of 2 sets. Before and after the training, the players tried to hit 10 balls that were pitched at 150 km/h. So that any changes in subjective hitting sense after the training could be identified, the players completed a questionnaire on that topic. In addition, their pre- and post-training batting performance and their batting motions were recorded with a high-speed video camera. All participants reported that the ball speed appeared to be slower after the training. Although there were some individual differences, that feeling seemed to be maintained for some time. Furthermore, when batting after the training, all participants made contact with the ball farther forward over the plate than before the training because of their improved perception of the ball. On the other hand, the number of strikes did not change, that is, there was no improvement in batting accuracy. The discussion suggests that, in order to improve batting accuracy, training with viewing very fast balls and hitting fast balls should be conducted regularly.

松橋瑠偉(筑波大学)，甲斐智大(鹿屋体育大学)，沼田薫樹(鹿屋体育大学)，柏木涼吾(鹿屋体育大学)，村上俊祐(鹿屋体育大学)，��橋仁大(鹿屋体育大学)

GPSを用いたラグビーのゲーム分析は，試合中の移動距離や走スピード，スプリント回数といった試合中のパフォーマンスの定量化を行った研究（古川, 2013）が行われている．サッカーにおいては，選手の動的な位置データを用いて，移動パターンおよび選手間の位置関係を測定することによって戦術的行動を評価する研究（Memmert et al., 2017）が行われている．しかし，GPSを活用したラグビーの研究は個人の移動様相を分析したものが多く，選手相互の位置関係を定量化した研究は行われていない．そこで，本研究の目的は，GPSから取得した位置データを用いて，7人制ラグビーのタックルにおける選手間距離を定量化することとした．その結果，ディフェンスラインの中にいる選手がタックラーである場合は，防御の成否に関わらずタックルにおける選手間距離を一定に保ちながら防御を行っており，ディフェンスラインの端にいる選手がタックラーである場合は，防御成功時にタックルにおける選手間距離が有意に短いことが明らかとなった．このことから，状況に応じてタックルにおける選手間距離を適切に保つことが防御において重要であると考えられる．今後は，攻撃状況や，防御状況等をより詳細に分類し分析を行うことで，現場で活用できる適切な選手間距離を定量できると考えられる．

Quantification with GPS of the distance between players when tackling in rugby sevens
GPS has been used in the analysis of rugby in order to quantify performance during games, such as distance traveled, running speed, and number of sprints. In soccer, evaluation of tactics has been done using the dynamic positional relations between players to measure movement patterns and distance between players. In rugby, however, most of the published studies using GPS analyzed the pattern of individuals’ motions; few studies have quantified relations between various players’ positions. The present study used GPS in rugby sevens to quantify the distance between players when tackling. It was found that when a player within the defense line become a tackler, the distance between the players was stable for defense, regardless of the success or failure of the tackle. Whereas, when a player at the end of the defense line became a tackler, the distance between the players was significantly shorter when the defense was successful. These results suggest that it is important when tackling to keep an appropriate distance between the players, depending on the situation. Further analysis of offense and defense situations may reveal the optimum distance between players.

川口啓太(明治大学)，八木快(筑波大学)，磯和純一朗(筑波大学)，奈良隆章(筑波大学)

本研究は内野手の一塁送球の正確性を高めるための練習方法を提案することを目的とした．筆者の考案した一塁送球時のターゲットの設定方法によって送球練習を一定期間実施することをトレーニング方法とし，一塁送球を行う際にターゲットを特別に設定していない，内野手を専門とする大学野球選手1名（A選手：年齢20歳，身長171.2cm，体重69.0kg，競技歴12年，内野手歴12年）を対象に，計8回トレーニングを実施した．各トレーニング日において，A選手には三塁手の定位置付近で捕球したゴロを一塁手の中心よりも左側をめがけて送球させ，これを30回繰り返させた．トレーニング実施前後に行った一塁送球テストの結果に向上傾向がみられたこと，A選手の内省において本トレーニング方法に対する肯定的な記述が見られたことから，一定の効果が期待できる．さらに，A選手の内省から，ターゲットを意識する中で導き出される動作に対する気づきがあることも示唆された．しかし，本研究では，動作比較を行っておらず，今後トレーニング効果を一層明確にするためには，動作分析をはじめとした詳細な検討が必要となるだろう.

Method for training a baseball infielder in order to improve his throwing accuracy
The present study investigated a method for training a baseball infielder that was aimed at increasing the accuracy of his throws to first base. In the study, a university baseball player (player A, age 20 years, height 171.2 cm, weight 69.0 kg, baseball experience 12 years, infield experience 12 years) who had no specific target when throwing to first base was given 8 sessions of training with the present authors’ method for setting up a target. In every training session, the player stood at third base, caught a ground ball, and threw it to the left side of the first baseman, repeating this 30 times. After that, the accuracy of his throws to first base improved. His introspective reports were positive, for example, he reported that he had become aware of the importance of the motion he made toward the target. However, because this study did not include any comparison of motions, more detailed analysis of infielders’ motions should be conducted in order to clarify further the effects of this training.

前田奎(筑波大学), 山元康平(福井工業大学), 広瀬健一(東京学芸大学), 大山卞圭悟筑波大学)

本研究では，男子やり投競技者の記録と体力との関係を検討することで，各競技レベルに必要とされる各種体力の基準値を提示することを目的とした．日本人男子やり投競技者138名（記録範囲：37.64-86.83m）を対象に，一般にフィールドテストやトレーニングで実施されている各種体力について質問紙法による調査を行い，やり投記録との関係を検討し，やり投記録に応じた標準値を作成した．各種体力とやり投記録との間には，30m走を除く全ての項目において有意な相関関係が認められた．また，相関関係の認められた項目について，やり投記録との単回帰式をもとに，40mから95mに至るまでの記録水準に応じた標準値を示した．本研究の結果から，やり投競技者には，身体の速度が高い状態において，全身で大きな力を発揮する能力が重要であることが示唆された．本研究で示した標準値は，競技者および指導者が，競技者の体力を適切に評価し，目標を設定する上で有用な資料であると考えられる.

Identifying standard values for the strength of male javelin throwers
The goal of the present study was to identify the standard strength required for male javelin throwers at various levels of competition. Male Japanese javelin throwers (N=138; range of record, 37.64 - 86.83 m) completed questionnaires asking about the strength that they used in field tests and training. The data from their responses were correlated with their javelin throw records, in order to obtain standard values. The correlation between strength and the other measures, except for 30-meter run times and javelin throw records, was significant. Among the significantly correlated items, standard values were calculated using a regression equation that included javelin throw records from 40 m through 95 m. The results suggest that javelin throwers must be able to perform with strong force when the speed of their body is high. The standard values obtained in the present study may enable athletes and coaches to get a more accurate evaluation of athletes’ fitness and set up more suitable goals.

森�ｱ由理江(宮崎大学)

本研究は，柔道初心者の前回り受身習得に向けた効果的な指導法と題し，使用するバランスボールの有効性について検証することを目的とした．被験者は，M大学教育学部の保健体育を専門とする大学生8名（男女比4：4）であり，柔道授業（90分×15回）においてバランスボールを使用した前回り受身の練習を毎授業行わせた．バランスボールの有効性を評価する項目として，授業前後での�@動画撮影による「受身動作」の変化，�Aアンケート調査による「恐怖感」の変化，�B授業終了後の被験者自身による「バランスボールの主観的効果」について検証した．その結果，前回り受身の持つ「回転軸が正中線から斜めにずれる」という難点と，「高さ」「勢い」のある投技に対して「恐怖感なく安全な受身をとる」という課題を解決する有効な手立てとなることが示唆された.

Effects of using a balance ball to teach forward-rolling ukemi to judo beginners
The present study examined a new method of teaching forward-rolling ukemi (break falls) to judo beginners by using a balance ball. The participants were 8 university students (4 males and 4 females) of the Faculty of Education of M university who were majoring in health and physical education. In 15 meetings of their judo class, they used a balance ball for 90 minutes in order to learn forward-rolling ukemi. The effects of practicing with a balance ball were evaluated by (a) videos of the participants’ ukemi motion before and after the classes, (b) questionnaires completed by the participants in which they reported by any change in their fear of forward-rolling ukemi, and (c) participants’ subjective evaluations of the lessons with the balance ball. The results suggested that the balance-ball method appeared to be effective for remedying the participants’ displacement of their axis of rotation from the midline when they did forward-rolling ukemi, and for acquisition of a safe ukemi that the participants could do without fear of high and strong throws.

杉山 敬(立命館大学)，服部琢磨(鹿屋体育大学)，亀田麻依(鹿屋体育大学)，前田 明(鹿屋体育大学)

本研究の目的は，重いボールによるフリースロー（以下，FT）シュートトレーニングが3ポイントシュート （以下，3Pシュート）に及ぼす影響を明らかにすることとした．対象者は大学男子選手12名とし，シュートパフォーマンスに差がないようトレーニング群（以下，Tr群）6名，コントロール群6名に分類した．トレーニングはFT 10球，3Pシュート10球の1セット20球を計3セット（計60球），週4回の4週間（計16回）行った．Tr群はFTのみ1 kgの7号球を用い，Tr群の3Pシュートとコントロール群の全ての試技は650 gの公式7号球を用いた．評価はシュートパフォーマンス（FT，6.25 m，3 P），遠投能力，最大筋力（肘・手関節），脚伸展パワーと内省報告とした．その結果，3Pシュート成功数はTr群において有意に増加した．その他の項目に交互作用は認められなかったが，Tr群の手関節最大筋力は上昇傾向（6.1%）がみられ，「シュートが楽に届くようになった」という内省報告も得られた．以上のことから，重いボールによるFTシュートトレーニングが3Pシュートの成功率向上に効果があることが明らかとなった.

Effects of free throw training using a heavier ball on three-point shots in basketball
The present study examined the effects of free throw (FT) training using a heavier ball on the three-point shots (3P shots) in basketball. The participants were 12 male collegiate basketball players; 6 were in the training group (Tr group), 6 in the control group. The training consisted of 10 FTs and 3P shots per set, 3 sets per training session. The Tr session was done 4 times a week and repeated for 4 weeks, for a total of 16 Tr sessions. The Tr group used a size 7 ball which was 1-kg for the FTs and an official size 7 ball (650 g) for the 3P shots. The control group used an official ball for both. The measures included FT and 3P shot performance, long distance throwing ability, maximum muscle force in the elbow and wrist, and leg extension power, plus introspective reports from the participants. The Tr group’s success rate with 3P shots increased significantly. No interactions were observed among the measures, but the maximum muscle force of the wrist of the participants in the Tr group showed a modest improvement (6.1%). Also, the Tr group participants’ introspective reports indicated that shooting had become easier. These results suggest that the FT training using a heavier ball would have improved the success rate of the Tr group participants’3P shots.

下川美佳(鹿屋体育大学)，金高宏文(鹿屋体育大学)，竹中健太郎(鹿屋体育大学)，近藤亮介(鹿屋体育大学)，濱中 良(米子工業高等専門学校)，前田 明(鹿屋体育大学)

本研究は，踏み込み動作の修正により右足踵部痛を改善した剣道競技者（S競技者）の取り組み事例について報告した．具体的には剣道競技者における，足裏全体踏み込みの習得過程と右足踵部痛改善前後の動作について比較し，踏み込み動作の修正により右足踵部痛を改善した事例の提示を目的とした．S競技者は，踵踏み込みを「つま先踏み込み」や「足裏全体踏み込み」に修正し，右足踵部痛を緩和させた．この右足踵部痛の緩和は，「体の重心を低くし右足指を丸める意識をした」ことで，踵に受ける衝撃が変わり，衝撃力や足底力を低下させたものと推察された．さらに，「足指を広げて踏む意識」をしたことにより，踵に受ける衝撃を足裏全体に分散したとも考えられる．以上のことから，踏み込み動作を「体の重心を低くし右足指を丸める意識」と「足指を広げて踏む意識」で修正することで，右足踵部痛は緩和する可能性が示唆された．

Lessening pain in the heel of the right foot of a kendoka by correcting the step-in motion
The present study examined a method for lessening pain in the heel of the right foot of kendoka S by correcting the step-in motion. The motions of the sole of foot when the kendoka was learning the step-in process and the motions before and after improvement in the pain were compared. From that analysis, a step-in motion to lesson the pain was proposed. S changed the step-in process from heel-first step-in to toe-first step-in or-sole step-in, and the pain was lessened. It was speculated that keeping the center of gravity of the body low and curling up the big toe of the right foot was the change that resulted in reducing the impact force to the heel. Further, by spreading the toes at step-in, force was dispersed to the whole sole of the foot. These results suggest that the pain in the heel of the right foot could be lessened by keeping the center of gravity of the body low, curling up the big toe of the right foot, and spreading the toes of the right foot when stepping in.

與谷謙吾(鹿屋体育大学), 前阪茂樹(鹿屋体育大学)

本研究は剣道で使用される特定の胴張型の竹刀を対象に，測定位置が異なる2つのストレインゲージセンサ(A33.5, B59.5)を用いて，打突以前の前方へ回転移動中の撓みについて調査した．その結果，実験1において，竹刀は回転移動開始から早期に変化を示し，回転移動方向と逆方向へ撓むことが明らかとなった．一方，竹刀の撓みの程度(ピーク)については，各センサ間で違いが観察された．実験1の結果を踏まえ，実験2においては，その範囲を回帰式を用いて算出したところ，A33.5が0.3-0.5cm，B59.5が0.4-0.7cmとなり，いずれも1cm未満の範囲であるものの，計測位置によって撓み量が異なることが示唆された.

Does the bamboo sword (shinai) used in kendo deflect during a forward swing? Investigation using a dobari type of shinai
The present study examined the deflection of the dobari-type of bamboo sword (shinai) used in kendo. The center of gravity of dobari-type shinai is located more toward the grip side, compared to other shinais. Because of this, they are easier to handle and feel lighter to swing. The deflection of the shinai during a forward swing was measured using two strain gauge sensors (A33.5 and B59.5). The sensors were placed 33.5 cm and 59.5 cm, respectively, from the tip of the shinai. In Experiment 1, the shinai was deflected in the opposite direction to the swing. Differences in the amount of deflection were found when the sensors’ measurements were compared (A33.5 < B59.5). In Experiment 2, the amount of deflection was calculated. At A33.5, it ranged from 0.3-0.5 cm, whereas at B59.5, it ranged from 0.4-0.7 cm. These results suggest that when the shinai is deflected during a forward swing, the amount of deflection observed depends on the location of the measuring point.

橋本恒(大阪教育大学),　柴原基(しばはら整形外科スポーツ関節クリニック),　水田有樹(しばはら整形外科スポーツ関節クリニック),　水島健太郎(誠仁会大久保病院),　久須美雄矢(誠仁会大久保病院)

［目的］本研究では非特異的腰痛と梨状筋症候群(以下PS)との関連を考察し,非特異的腰痛への多角的な理解を深めることによって，当該の腰痛に対する適切な対処方法の提案を目的とする.［方法］非特異的腰痛と診断されたスポーツ選手20名と腰痛を持たないスポーツ選手22名(コントロール群)を対象とし,超音波診断装置Aixplorerから得た治療前後の梨状筋中間部の弾性率の測定,下肢伸展挙上検査,股関節屈曲外転外旋検査,およびNumerical Rating Scalの4つの測定項目から得られた数値の有意差を治療前後に検証し,併せてコントロール群の数値においても検証した.［結果］調査対象者の治療前後を比較した結果、上記の4項目全てにおいて数値は有意に低値を示すとともに,治療後とコントロール群間では有意差は確認できなかった.［考察］PSを伴う神経絞扼の解放および仙腸関節の機能不全の修正により,非特異的腰痛の減少に有用であると思われる.［結論］PSが非特異的腰痛の原因の一つであると示唆された.また,超音波診断装置Aixplorerを用いることにより,非特異的腰痛の原因がPSと疑われるスポーツ選手の評価において,無痛かつ非侵襲的にして客観的な診断方法であることも明らかにされた.

A new method for diagnosing and evaluating athletes’ nonspecific low back pain using ultrasound elastography: focusing on piriformis syndrome
[objective] The present study examined the relationship between nonspecific low back pain and piriformis syndrome (PS), in order to gain a better understanding of nonspecific low back pain.
[method] Participants were 20 athletes with nonspecific low back pain and 22 athletes without back pain (control group). The elasticity of the central segments of the piriformis muscle was measured before and after treatment using ultrasound elastography (Aixplorer). From examination of the results of measuring the extension and elevation ability of the lower leg, results when bending and from hip adduction and abduction, a numerical rating scale was developed to enable comparison between the participants’ scores before and after the treatment, as well as in comparison to the control group’s scores, in order to examine the efficacy of the treatment.
[results] All 4 measurements had significantly lower values after treatment compared to before treatment. No significant difference was observed between the after-treatment measures of the participants with back pain and those in the control group.
[discussion] Release of nerve compression associated with piriformis syndrome and treatment of dysfunction of the sacroiliac joint may well be useful for reducing nonspecific low back pain.
[conclusion] Piriformis syndrome may be one of the causes of nonspecific low back pain; treatment of dysfunction of the sacroiliac joint may well be useful in reducing piriformis syndrome. Ultrasound elastography (Aixplorer) may be useful with athletes whose nonspecific low back pain may have been caused by piriformis syndrome, as an objective, non-invasive, pain-free diagnostic method.