本研究ではスポーツ科学の手法を用いて，サラブレッドの走動作において優れたウマの走動作，ならびに騎手の望ましい騎乗動作を力学的な視点から解明することを目的としている．研究３年目の2020年度はJRA競走馬総合研究所内の屋外馬場において，サラブレッド１頭を被験馬とし騎乗者２名を対象とした．騎乗者の主観的判断による速度ではあるが，常歩、速歩、駈歩における歩容をモーションキャプチャ装置および高速度カメラよって撮影し，被験馬および騎乗者の歩容特徴を観測した．ウマ・騎乗者の身体に貼付した反射マーカーによって得られた関節標識点から身体セグメントを抽出し，その後先行研究によるウマおよび騎乗者の身体重心推定式を用いることでウマと騎乗者の身体重心変動を抽出した．今回の実験条件では同一のウマに異なる騎乗者が乗って，ほぼ同一の速度域で各歩容条件を再現したが，このときウマの上に乗る騎乗者の重心変動の時間変化には個人間で異なった傾向が見られた．具体的には馬上の騎乗者は鎧，鞍の上で自身の身体操作によってウマに対しての重心位置を変化させる．所謂天神乗りと呼ばれる乗馬で用いられるアップライト姿勢での騎乗では膝関節の伸展，股関節伸展による体幹の起こし動作といった操作によって，重心を意図的に上方へと動かすことが行われているが，この体の使い方は重心変動の時系列情報として現れることを確認することができた．特にウマの重心が最下点に移動したのちに上方へと方向転換をし，上昇速度を上げていく際に騎乗者の重心はそれに先んじて上方への速度を獲得する．つまり騎乗者は馬の背に乗っているだけでなく，自らの身体操作によってウマから突き上げられることなく，自発的に上に重心を移動させている．その動作について詳細に見ると騎乗者による差がみられた．これまで騎乗者の騎乗法に定量化された事例はなく，計測方法の確立によって騎乗者の技能の可視化についての道が拓けたと言える．
The purpose of this study is to elucidate the excellent running motion of horses in the running motion of thoroughbreds and the desirable riding motion of jockeys from a mechanical point of view by using the method of sports science. In 2020, the third year of the research, one thoroughbred was used as a test horse and two riders were targeted at the outdoor riding ground in the JRA Racehorse Research Institute. Although the speed was determined by the rider's subjective judgment, the gait characteristics of the test horse and the rider were observed by photographing the gaits in walk, trot, and canter with a motion capture device and a high-speed camera.
Body segments are extracted from the joint marking points obtained by the reflex markers attached to the horse / rider's body, and then the changes in the body center of gravity of the horse and the rider are used by using the horse and rider's body center of gravity estimation formula from previous studies. Was extracted. In this experimental condition, different riders ride on the same horse and each gait condition is reproduced in almost the same speed range, but at this time, the time change of the center of gravity of the rider riding on the horse is between individuals. A different tendency was seen in. Specifically, the rider on horseback changes the position of the center of gravity with respect to the horse by manipulating his body on the armor and saddle. In the so-called Tenjin riding in the upright posture used in horseback riding, the center of gravity is intentionally moved upward by operations such as extension of the knee joint and raising of the trunk by extension of the hip joint. It was confirmed that this usage of the body appears as time-series information of the change in the center of gravity.
In particular, the center of gravity of the horse moves upward after moving to the lowest point, and when the ascending speed is increased, the center of gravity of the rider acquires the upward speed ahead of that. In other words, the rider not only rides on the back of the horse, but also voluntarily moves the center of gravity upward without being pushed up from the horse by his own physical manipulation. Looking at the movement in detail, there was a difference depending on the rider. So far, there have been no quantified cases of rider riding methods, and it can be said that the establishment of measurement methods has paved the way for visualization of rider skills.
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