Updated on 2022/06/30

写真a

 
FUJITA, Zenya
 
Affiliation
Faculty of Sport Sciences, School of Sport and Sciences
Job title
Associate Professor

Concurrent Post

  • Affiliated organization   Global Education Center

Education

  •  
    -
    2012

    Graduate School of Waseda University   Graduate School, Division of Sports Science  

  •  
    -
    2007

    Waseda University   Department of Sport Sciences  

Degree

  • Waseda University   Ph. D.

Research Experience

  • 2012.04
    -
    2015.03

    Institute of Sports Sciences   Department of Sports Sciences   Researcher

Professional Memberships

  •  
     
     

    日本コーチング学会

  •  
     
     

    日本バイオメカニクス学会

  •  
     
     

    日本体育学会

 

Research Areas

  • Sports sciences

Research Interests

  • Sports science

Papers

  • クロスカントリースキー競技におけるダイアゴナル走法の機能的経過分析に基づく観察評価基準の検討

    井川純一, 藤田善也, 鈴木典鈴木典, 水落文夫, 青山清英

    桜門体育学研究   56   5 - 18  2021.03  [Refereed]

  • Evaluation of the diagonal technique in cross-country skiing by biomechanical and functional analysis

    Igawa Junichi, Nagano Tomoki, Fujita Zenya, Suzuki Tsukasa, Mizuochi Fumio, Seki Keitaro, Aoyama Kiyohide

    The Japan Journal of Coaching Studies   34 ( 1 ) 47 - 60  2020

     View Summary

    <p>&nbsp;&nbsp;&nbsp;&nbsp;In this study, we reviewed the literature on the gliding technique for diagonal-stride cross-country skiing from the perspectives of biomechanical and functional analysis; both of these assess cross-country skiing "externally". By comparing the results of these analyses, we identified the main focus areas of the gliding technique evaluation using motion analysis. <BR>&nbsp;&nbsp;&nbsp;&nbsp;1) The temporal order of the movement processes between the phases was different for the early deceleration phase of biomechanical analysis and the primary functional and preparatory secondary phases of functional analysis. <BR>&nbsp;&nbsp;&nbsp;&nbsp;2) The temporal order of the functional phase movement processes was the same in the late deceleration phase of biomechanical analysis and the transitional secondary phases of functional analysis; however, the movement tasks were different. <BR>&nbsp;&nbsp;&nbsp;&nbsp;3) The challenges identified in the actions associated with achieving the movement tasks were different in each of the phases. Biomechanical analysis was most important in the analysis of singular movements. On the other hand, functional analysis was more important in the analysis of multiple simultaneous movements. <BR>&nbsp;&nbsp;&nbsp;&nbsp;In this study, both biomechanical analysis and function analysis were found to have merits and demerits, however results that compared both analyses were found to be most beneficial. Functional analysis grasped the functional unit of movement, considering movement task as an important step in the movement process. Functional analysis provides important findings on movement affinity for the mastery of the movement. <BR>&nbsp;&nbsp;&nbsp;&nbsp;Therefore, functional analysis can be an important finding, as athletes and coaches are concerned with the practicalities of movement. Functional analysis is better than biomechanical analysis, as it can help in the practical aspects of coaching. <BR>&nbsp;&nbsp;&nbsp;&nbsp;These findings will make it easier to perform the technicalities of coaching cross-country skiing diagonal strides for both coaches and athletes.</p>

    DOI CiNii

  • クロスカントリースキー競技における用具の長さ情報を利用したクラシカル走法のサイクル特性分析アプリケーションの開発

    藤田善也

    スポーツ科学研究   16   26 - 32  2019.09  [Refereed]

     View Summary

    クロスカントリースキー競技において,競技パフォーマンスである滑走速度とサイクル特性との関係は深く,走法によって異なる関係性があることが知られている.本研究の目的は,競技現場で取得可能な用具の長さ情報を用いたサイクル特性の分析アプリケーションを開発し,その精度を検証したうえで,選手のサイクル特性を事例的に明らかにすることであった.その結果,1)簡単なマウス操作とキーボード操作によって,競技現場のコーチや選手が滑走速度,ストライド長,サイクル頻度,ポーリング時間およびスイング時間を容易に取得できること,2)開発したアプリケーションの精度について,従来の DLT 法と同程度であること,が示された.また,今回開発したアプリケーションを用いて日本代表選手と大学生選手のダブルポーリング走法中のサイクル特性を比較した結果,日本代表選手の滑走速度が高いこと,男子日本代表選手はストライド長を長くしてより高い滑走速度を獲得していること,女子日本代表選手はサイクル頻度を高くしてより高い滑走速度を獲得していることが示唆された.

  • Kinematic Characteristics of Curve Skating in a 300 m Time Trial Race Among Top Roller Speed Skaters

    Fumitake Okabe, Chiho Takao, Zenya Fujita, Jun Tsuchiya

    International Journal of Sport and Health Science   17   235 - 242  2019

    DOI J-GLOBAL

  • Characteristics of roller speed skaters in a 300-m time trial race in the world roller speed skating championships

    Okabe Fumitake, Takao Chiho, Fujita Zenya, Tsuchiya Jun

    Taiikugaku kenkyu (Japan Journal of Physical Education, Health and Sport Sciences)   64 ( 2 ) 869 - 876  2019

     View Summary

    The purpose of this study was to investigate the racing characteristics of elite roller speed skaters in a 300-m time trial race (300m TT). The subjects were 21 skaters who participated in the World Roller Speed Skating Championships in 2016. These included 9 skaters who qualified for the finals and 12 who ranked between the 25th and 45th places. Roller speed skaters glide while keeping their feet grounded for a short time in a curve: a movement known as "carrying". Nine finalists who performed carrying in C2 and C3 were classified as the top group (age 24.2 ± 2.4 years; height 1.8 ± 0.1 m; weight 73.2 ± 7.1 kg). Nine of 12 skaters who performed carrying in C2 and C3 were classified as the subgroup (age 24.0 ± 3.4 years; height 1.8 ± 0.1 m; weight 74.6 ± 7.1 kg), and 3 skaters were classified as the non-carrying group (age 25.0 ± 5.1 years; height 1.8 ± 0.0 m; weight 73.7 ± 2.4 kg). In this study, 300mTT was classified as 4 straight sections – Start, S1, S2, and Finish – and 3 curve sections – C1, C2, and C3. The investigated parameters included the 300mTT goal time (T300), the skating speed in each section, and the time during which carrying was performed (Tcar). In the subgroup and non-carrying group, the skating speeds in S1 were similar, but the skating speed of the non-carrying group in C2 was lower than that of the subgroup. The top group glided at a higher skating speed in every section expect C3. There was no significant difference in Tcar, and there was no significant correlation between T300 and Tcar in C2 and C3. There was a significant positive correlation between T300 and Tcar in C2. In the top group, there was a significant negative correlation between T300 and skating speed at C2. These results suggest that carrying in C2 is important for gliding at a higher skating speed in 300mTT, and that Tcar in C2 and C3 for elite roller skaters does not influence T300. Elite roller skaters had superior acceleration capacity in the Start, and obtained a higher skating speed until S1, after which they maintained a higher skating speed in C2. Furthermore, elite roller skaters were able to achieve a higher skating speed in spite of fatigue in their support legs.

    DOI CiNii

  • The kinematics of curve skating for Japanese roller speed skaters in the 300-m time trial race

    Okabe Fumitake, Takao Chiho, Fujita Zenya, Tsuchiya Jun

    The Japan Journal of Coaching Studies   33 ( 1 ) 55 - 64  2019

     View Summary

    <p>&nbsp;&nbsp;&nbsp;&nbsp;The study aimed to investigate the kinematics of curve skating among national-level Japanese roller speed skaters and world-class skaters in the 300-m time-trial race. The subjects were 12 finalists who were classified as world-class skaters (age, 24.9±4.1 years, height, 177.0±6.0 cm, weight, 73.0±5.2 kg) and 3 Japanese skaters (age, 18.7±0.5 years, height, 169.0±0.0 cm, weight, 64.3±3.1 kg) in the World Roller Speed Skating Championships in 2016. Data on the three-dimensional coordinates were calculated using the direct linear transformation technique. Parameters included the displacement of distance between the center of curvature and the center of body mass at the end and start of stroke, the skating length, speed, the stroke frequency, time in the one- and dual-leg supporting phase, side tilt angle, and segment angle. This study found the following: Japanese skaters (1) glided while climbing the incline owing to their low stroke frequency; therefore, their skating velocity additionally decreased; (2) were unable to control their center of body mass (COM) because they tilted their left shank less inward in the first half of the left stroke, (3) performed larger push-off movements in the duration of the dual-leg supporting phase in both strokes; and (4) restrained their COM as they tilted their shank less forward after tilting backward in both strokes; therefore, their skating velocity in the skating direction was lower.</p>

    DOI CiNii

  • Acquisition of the course profile and pre-competition race analysis of cross-country skiing in the Peyongchang Winter Olympic Games::The men's 15km+15km skiathlon

    Yanaka Takuya, Nakazato Kosuke, Fujita Zenya, Ishige Yusuke

    Taiikugaku kenkyu (Japan Journal of Physical Education, Health and Sport Sciences)   64 ( 1 ) 249 - 263  2019  [Refereed]

     View Summary

    Cross-country skiers perform over a long distance using poles and skis. Physical fitness, in terms of factors such as VO2max and muscle strength, skiing technique and race strategy are important for winning competitions. To plan the race strategy, investigations of the course profile and race analysis are needed. The purposes of this study were to investigate cross-country skiing course profiles which were planned for the Winter Olympic Games at Peyongchang, and to analyze the men's 15km+15km World Cup skiathlon race (SA) as a pre-competition event. A cross-country skier followed the classical and skating courses using a GNSS (Global Navigation Satellite System) antenna. The antenna instantly measured the latitude, longitude and height of the skier on the courses. The coordinate values on a plane were calculated from latitude and longitude, after the inclination was then calculated from the coordinate values and height every 10 m. The overall finish time and transit time at 24 points for 12 skiers in SA were retrieved from the Official Home Page of the International Ski Federation (FIS), and the segment times among the various points were calculated. Three segment times formed a lap, and each segment speed was calculated by dividing the segment distance by the segment time. For the classical course profile, the distance was 3819 m and the maximum inclination was 18.6%. In contrast, for the skating course, the distance was 3777 m and the maximum inclination was 20.6%. No correlation was found between the overall finish time and the segment times for the classical course. This result was attributable to small variations in the lap times for the classical course because of the skiers' use strategy, checking among competitors, and the mass-start. On the other hand, positive correlations were found between the overall finish time and the segment times on skating. In skating, the segment speeds from the final phase of the 2nd lap to the middle phase of the 3rd lap indicated deceleration relative to the 1st lap. These results suggest that gliding on a skating course in a short time is important for shortening the overall finish-time. Especially, it is important to minimize the deceleration of the 2nd and 3rd lap segment speed. The race pattern for the Olympic Games was similar to that of pre-competition, except for the time taken. These results indicate that pre-competition race analysis is useful for devising a strategy for target competition.

    DOI CiNii

  • Pose tracking with rate gyroscopes in alpine skiing

    Shinsuke Yoshioka, Zenya Fujita, Dean C. Hay, Yusuke Ishige

    Sports Engineering     1 - 12  2017.11  [Refereed]

     View Summary

    The motion capture of alpine skiing is technically challenging. Motion capture systems using inertial sensors such as gyroscopes and accelerometers have begun to be used in sport. The capture volume of the system can be large enough to cover the whole area of a particular sporting event, because sensors are affixed to the human body itself. The current study developed a method of tracking the pose of an alpine skier using gyroscopes for 3 min with a tracking error of 2° (RMSE). The technical significance of the presented method, which uses one common simple algorithm to improve measurement of pose, applies to many experimental conditions. The adoption of a high resolution (24 bit) analog-to-digital converter and high sampling rate (1 kHz) also contribute to the improvement of measurement time.

    DOI

  • クロスカントリースキー競技における競技パフォーマンスに優れた選手のダイアゴナル走法のキネマティクス的特徴

    藤田善也

    スポーツ科学研究   14   47 - 56  2017.07  [Refereed]

     View Summary

    本研究の目的は,クロスカントリースキー競技中のダイアゴナル走法を対象に競技パフォーマンスに優れた選手のキネマティクス的特徴を明らかにすることであった.15 kmクラシカル競技に参加した成人男子クロスカントリースキー選手を6度の上り坂の地点で撮影した.被験者は,競技成績によって上位群と下位群に分類した.比較の結果,競技パフォーマンスに優れた選手は,(1)大きいストライド長を獲得していること,(2)スキーを離地させてからポールを接地させるまでの滑走時間が長いこと,(3)ポールを接地してから比較的早い段階で肘を伸展させていること,(4)プッシュオフ動作時にスキーと雪面とをすばやくグリップさせ,その後,膝関節をすばやくかつ大きく伸展させていることが明らかとなった.

  • 特集/エンデュランス・トレーニング 現在の体力レベルを知りトレーニング強度を算出する

    藤田善也

    コーチング・クリニック   31 ( 4 ) 12 - 15  2017.03

  • A study on the technical factors in curve skating on a flat track among Japanese inline speed skaters

    Okabe Fumitake, Fujita Zenya, Tsuchiya Jun

    The Japan Journal of Coaching Studies   30 ( 2 ) 97 - 108  2017  [Refereed]

     View Summary

    <p>&nbsp;&nbsp;&nbsp;&nbsp;The purpose of this study was to investigate the technical factors in curve skating in inline speed skating on a flat track by comparing between an elite skater (n=1) and a trained skater (n=1) in flat track. Data on the three dimensional coordinates of the skaters who participated in the 60th East Japan Roller Speed Skating Championship were collected to calculate kinematic parameters such as the trajectory of the center of body mass, joint and segment angles of the support leg, and tilt angles of the body and shank of the support leg during the curve skating using the direct linear transformation technique. In the left leg stroke of the top skater, the forward rotation of the thigh was greater than the forward bent of the shank and the forward movement of the center of the body mass was greater than that in the left leg stroke of the trained skater. The tilt angles of the body and the shank of the support leg to the inside of the curve of the top skater were greater than those of the trained skater. The top skater tilted the body and the shank of the support leg sideward largely during the right and left leg strokes. These results suggest that high degrees of rotation of the thigh of the support leg, and tilting of the body and the shank of the support leg to the inside of the curve were good technical factors in curve skating among Japanese inline speed skaters.</p>

    DOI CiNii J-GLOBAL

  • Automatic Identification of Subtechniques in Skating-Style Roller Skiing Using Inertial Sensors

    Yoshihisa Sakurai, Zenya Fujita, Yusuke Ishige

    SENSORS   16 ( 4 )  2016.04  [Refereed]

     View Summary

    This study aims to develop and validate an automated system for identifying skating-style cross-country subtechniques using inertial sensors. In the first experiment, the performance of a male cross-country skier was used to develop an automated identification system. In the second, eight male and seven female college cross-country skiers participated to validate the developed identification system. Each subject wore inertial sensors on both wrists and both roller skis, and a small video camera on a backpack. All subjects skied through a 3450 m roller ski course using a skating style at their maximum speed. The adopted subtechniques were identified by the automated method based on the data obtained from the sensors, as well as by visual observations from a video recording of the same ski run. The system correctly identified 6418 subtechniques from a total of 6768 cycles, which indicates an accuracy of 94.8%. The precisions of the automatic system for identifying the V1R, V1L, V2R, V2L, V2AR, and V2AL subtechniques were 87.6%, 87.0%, 97.5%, 97.8%, 92.1%, and 92.0%, respectively. Most incorrect identification cases occurred during a subtechnique identification that included a transition and turn event. Identification accuracy can be improved by separately identifying transition and turn events. This system could be used to evaluate each skier's subtechniques in course conditions.

    DOI

  • A study of the choice of sub-techniques and skis for classical-style cross-country skiing: Focusing on the double poling and herringbone sub-techniques with skating-style skis

    Fujita Zenya, Sakurai Yoshihisa, Ishige Yusuke

    Taiikugaku kenkyu (Japan Journal of Physical Education, Health and Sport Sciences)   61 ( 1 ) 271 - 279  2016  [Refereed]

     View Summary

    The purpose of this study was to identify differences in (1) total skiing time and (2) lap time for different course situations in cross-country skiing (uphill, flat and downhill) between classical-style sub-techniques using classical skis and double poling and herringbone sub-techniques using skating skis. The subjects were 5 college cross-country skiers who performed at maximal effort in 2 different trials: classical-style sub-techniques while wearing classical-style skis (CL), and double poling and herringbone sub-techniques while wearing skating-style skis (DP). Skiing velocity was measured with a global navigation satellite system module and mobile PDA. The sub-techniques employed were recorded with a small video camera. It was found that a strategy using DP (1) significantly increased the skiing time, (2) increased the skiing velocity on downhill and decreased it on uphill, and (3) was associated with a tendency to use double poling on uphill.

    DOI CiNii

  • 05バ-27-ポ-39 クロスカントリースキー競技で使用ざれるグリップワックスの有無が競技パフォーマンスに及ぼす影響(05 バイオメカニクス,一般研究発表,2020東京オリンピック・パラリンピックと体育・スポーツ科学研究)

    藤田 善也, 桜井 義久, 石毛 勇介

    日本体育学会大会予稿集   66   214 - 214  2015

    DOI CiNii

  • Automated Identification and Evaluation of Subtechniques in Classical-Style Roller Skiing

    Yoshihisa Sakurai, Zenya Fujita, Yusuke Ishige

    JOURNAL OF SPORTS SCIENCE AND MEDICINE   13 ( 3 ) 651 - 657  2014.09  [Refereed]

     View Summary

    The aims of the present study were (1) the development of an automated system for identifying classical-style ski subtechniques using angular rate sensors, and (2) the determination of the relationships among skiing velocity, ski course conditions, and ski subtechniques using a global navigation satellite system (GNSS) and the developed automated identification system. In the first experiment, the performance of a male cross-country skier was used to develop an automated system for identifying classical-style ski subtechniques. In the second one, the performances of five male and five female college cross-country skiers were used to validate the developed identification system. Each subject wore inertial sensors on both wrists and both roller skis, a small video camera on the helmet, and a GNSS receiver. All subjects skied a 6,900-m roller ski course using the classicalstyle at their maximum speed. The adopted subtechniques were identified by the automated method based on the data obtained from the sensors, and also by visual count from a video recording of the same ski run. The results showed that the automated identification method could be definitively used to recognize various subtechniques. Specifically, the system correctly identified 9,307 subtechnique cycles out of a total of 9,444 counted visually, which indicated an accuracy of 98.5%. We also measured the skiing velocity and the course slope using the GNSS module. The data was then used to determine the subtechnique distributions as a function of the inclination and skiing velocity. It was observed that male and female skiers selected double poling below 6.7 degrees and 5.5 degrees uphill, respectively. In addition, male and female skiers selected diagonal stride above 0.7 degrees and 2.5 degrees uphill, and below 5.4 m/s and 4.5 m/s velocity, respectively. These results implied that the subtechnique distribution plot could be used to analyze the technical characteristics of each skier.

  • バ27-124 クロスカントリースキー競技のスキー反力センサシステムの開発(05 バイオメカニクス,一般研究発表抄録)

    藤田 善也, 石毛 勇介

    日本体育学会大会予稿集   65   170 - 170  2014

    DOI CiNii

  • クロスカントリースキー競技における競技パフォーマンスとサイクル特性との関係:男子10 km クラシカル競技種目を対象として

    藤田善也, 石毛勇介, 吉岡伸輔, 竹田正樹

    体育学研究   59 ( 1 ) 275 - 282  2014  [Refereed]

     View Summary

    The purpose of this study was to evaluate the relationships between race performance and cycle characteristics in a 10-km classic-style men's cross-country ski competition. The subjects were competitors in the 89th Japan National Ski Championships. Skiing motions of the subjects on flat stretches (1.5 km and 6.5 km) and uphill slopes (1.7 km and 6.7 km) were videotaped using two high-speed cameras. Cycle characteristics were calculated based on measurement of hip displacement and cycle time. It was revealed that elite competitors (1) performed at high velocity at all measurement points, (2) reduced their velocity in the last half of the race, (3) achieved a high velocity in double poling and diagonal stride, (4) increased their cycle length and cycle rate when employing the double poling technique, and (5) increased their cycle length when employing the diagonal stride technique.

  • クロスカントリースキー競技のV2スケーティング走法中の滑走速度とスキー板に対する力の各軸方向成分との関係

    藤田善也, 吉岡伸輔, 桜井義久, 石毛勇介

    バイオメカニクス研究   18 ( 1 ) 2 - 8  2014  [Refereed]

     View Summary

    The purpose of this study was to identify relationships between the skiing velocity and each axial force components on the ski during V2-skate technique. Fifteen elite cross-country skiers performed at their maximal efforts. Ski reaction forces were measured using specific ski sensors, the A/D converter, the transmitter, and the personal computer. The skiing
    velocity was recorded by the laser distance meter. Skiers exerted the skier generated force on downward in vertical, medial, and posterior directions
    in the coordinate system of the ski during the push-off phase. The peak force on downward in the vertical direction of the ski positively correlated with the skiing velocity. In contrast, the peak force on the medial
    direction of the ski negatively correlated with the skiing velocity. Those results suggested that cross-country skiers increased the skiing velocity
    by increasing the force on downward in the vertical direction and decreasing the force on the medial direction of the ski during the push-off
    phase in the V2-skate technique.

  • 05バ-28-ポ-38 クロスカントリースキー競技クラシカル種目における競技パフォーマンスと各サブ走法との関係(05 バイオメカニクス,一般研究発表抄録)

    藤田 善也, 吉岡 伸輔, 石毛 勇介

    日本体育学会大会予稿集   64   206 - 206  2013

    DOI CiNii

  • Motion analysis of cross-country skiing at the 21st Olympic Winter Games Vancouver 2010 and all-Japan ski championships

    T. Suzuki, F. Mizuochi, M. Takeda, Z. Fujita, M. Nozaki, S. Ito

    Science and Nordic Skiing II     95 - 101  2013

  • クロスカントリースキーのバイオメカニクス

    藤田善也, 吉岡伸輔

    体育の科学   63   227 - 234  2013

  • クロスカントリースキー競技におけるバイオメカニクス的観点からの競技サポート

    藤田善也

    バイオメカニクス研究   17   189 - 200  2013

  • 散布した点の代表値を示す尺度「プレー重心」の提案と精度の検討

    樋口智洋, 衣笠竜太, 藤田善也, 堀野博幸, 土屋純

    スポーツ科学研究   9   338 - 349  2012.11  [Refereed]

     View Summary

    記述分析法に関してプレー重心は散布したプレー回数の代表値を示す尺度として妥当であること,また,記述分析法がデジタル測定法と同等の精度を持つことが明らかとなった.

  • 05バ-22-ポ-19 クロスカントリースキー競技会におけるクラシカル種目の各走法のサイクル特性と競技成績との関係(バイオメカニクス,ポスター発表,一般研究発表抄録)

    藤田 善也, 石毛 勇介, 吉岡 伸輔

    日本体育学会大会予稿集   63   163 - 163  2012

    DOI CiNii

  • テニスのフォアハンドストロークにおけるクロススタンス打法のキネマティクス

    トレーニング科学   22   31 - 38  2012  [Refereed]

  • クロスカントリースキー・V2スケーティング走法中の推進力に対する上肢と下肢の貢献

    藤田善也, 吉岡伸輔, 石毛勇介, 田内健二, 土屋純

    スポーツ科学研究   9   41 - 55  2012  [Refereed]

     View Summary

    This study aims to quantify the degree of contribution of arms and legs during V2 skate in cross-country skiing from the viewpoint of the force along the direction of acceleration. Method: Six male cross-country skiers performed V2 skate at a speed of 6 m/s, and the pole and ski reaction forces were measured. In addition, using a high-speed camera, the three-dimensional coordinates of each part
    of the body were obtained, and the velocity, the pole, and ski angles were calculated, which were then
    converted to the force along the direction of movement. Results: The peak and mean forces along the direction of movement were 100 ± 20 and 63 ± 12 N, respectively, for the pole (one side) and 202 ± 48
    and 106 ± 18 N, respectively, for the ski (one side). Those suggested that in V2 skate at a speed of 6
    m/s, the degree of contribution of the force due to arms(push of both poles)and leg(push-off of right
    or left ski)are approximately the same. Furthermore, when pushing off with the ski, although the force component perpendicular to the ski comprises a large proportion, it was shown that the force can be
    divided into lateral and horizontal directions by converting it to a global coordinate system using the
    ski edge and orientation angle. In addition, ski edge angle was changed depending on abduction of hip
    joint. Ski force propulsion was generated by bduction of hip joint and extension of hip and knee joint.
    Hence, this implies that in order to increase the force of push-off for hip abduction and extension and
    knee extension movement, it is important to point the force along the direction of movement while exerting a force perpendicular to the ski.

  • 女子クロスカントリースキー選手の滑走速度を高める技術に関する事例研究:フライト局面発生を伴ったV2スケーティング走法に着目して

    藤田善也, 吉岡伸輔, 石毛勇介, 田内健二, 土屋純

    体育学研究   57 ( 2 ) 653 - 662  2012  [Refereed]

     View Summary

    The aim of this study was to clarify how coaching in the V2 skate technique, intentionally including the flight phase, affects the skating velocity of female cross-country skiers. First, seven female skiers performed the V2 skate technique at maximal effort. Next, five subjects who did not have any flight phase in their V2 skate technique were trained to perform it along with the flight phase for about 10 minutes, and were then asked to execute the flight phase. In this test, the subjects used poles and skis equipped with force sensors, and their velocity was recorded. After the test, each subject was interviewed about her subjective experience of the V2 skate including the flight phase. It was found that the training caused all of the subjects to change the V2 skate so that it included the flight phase. Moreover, during skating attempts with the flight phase, both the skating velocity and the peak and average forces of the pole and ski increased significantly. The interviews revealed that three subjects felt a sense of fear when they were airborne, and that four subjects felt close to loss of balance. These results suggest that training in the V2 skate with a flight phase was effective for increasing the skating velocity of the female skiers. Moreover, it was evidently difficult for the female skiers to learn to skate with flight phases through a normal training method because of the sense of fear they experienced during the maneuver.

  • クロスカントリースキーのスタート局面におけるクラシカル走法の技術の特徴

    藤田善也

    スポーツ科学研究    2011  [Refereed]

     View Summary

    本研究は,クロスカントリースキー競技クラシカル種目のスタート局面におけるダブルポーリング走法およびダイアゴナル走法をキネマティクス的手法を用いて解析し,それぞれの走法の特徴を明らかにすることで,加速局面においてより高い滑走速度を得るための示唆を得ることを目的とした.被験者は,日本代表を含む大学クロスカントリースキー競技者 5 名とした.被験者には,雪上での 50m の直線コースにおいて,ダブルポーリング走法およびダイアゴナル走法,さらに被験者が最も滑走速度が高くなるように前述の 2 走法を自由に組み合わせた試技(以下,コンビネーション試技)を用いて静止した状態から最大努力で滑走させた.被験者の実施をレーザー瞬時速度測定器と高速度ビデオカメラを用いて記録し,50m の所要時間,10m 毎の平均速度および最高速度,総サイクル数,ピッチおよびストライドを算出した.その結果,(1) 50m の所要時間に差はみられなかった,(2) 最高速度はダブルポーリング走法がダイアゴナル走法と比較して有意に高値を示した,(3) 滑走速度は,10-20m 区間においてはダイアゴナル走法がダブルポーリング走法より有意に高値を示し,(4) 30-50m 区間においてはダブルポーリング走法がダイアゴナル走法より有意に高値を示した,(5) コンビネーション試技は,スタート直後にダイアゴナル走法を実施し,その後ダブルポーリング走法に切り替えて実施されていた.以上の結果から,クラシカル種目におけるスタート局面では,まずスタート直後の加速に優れるダイアゴナル走法を用いて,次にダイアゴナル走法より最高速度の高いダブルポーリング走法に切り替えるというコンビネーション技術が,高い滑走速度を得るために重要となることが示唆された.

  • A relationship between the occurrence of the flight phase and the increase velocity during V2 skating

    Zenya Fujita, Yusuke Ishige, Shinsuke Yoshioka, Kenji Tauchi, Shigeo Iso, Senshi Fukashiro, Jun Tsuchiya

    International Journal of Sport and Health Sciences   8   113 - 120  2010  [Refereed]

     View Summary

    Two types of profiles of ski reaction forces during V2 skating have been reported by previous investigations. One of the differences between these two profiles is in the existence of the “flight phase,” i.e., the phase in between gliding and kicking off, in which the skis float above the snow while skiing. It has been suggested that the difference is caused by the skating velocity. The purpose of this study is to clarify whether or not there is a relationship between the occurrence of the flight phase and the increase in velocity during V2 skating. Seven elite male cross-country skiers performed two types of trials at different velocities (high and medium speeds). The high and medium speeds correspond to the competitive pace for a sprint race and a 10-km race, respectively. The kinematics was measured for each trial using two video cameras and a panning direct linear transformation technique. The flight phase was determined by the ski load data obtained from a sensor attached to the ski. No flight phase was confirmed during medium-speed skating, but a flight phase was confirmed during high-speed skating, indicating the existence of the flight phase is related to an increase in skating velocity. However, the hip- and knee-joint angles and the vertical displacement of the center of mass were not changed by an increase in skating velocity. These results suggested that the flight phase was a small change from the standpoint of kinematics, but it may cause changes in muscle activity since the leg muscle groups experience no ground reaction force.

  • やり投の日本トップ選手における動作分析データの活用事例 ‐世界トップレベルとの相違点を提示して‐

    田内健二, 村上幸史, 藤田善也, 礒繁雄

    スポーツパフォーマンス研究   1   151 - 161  2009  [Refereed]

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Books and Other Publications

Misc

  • Kinematic Characteristics of Curve Skating in a 300 m Time Trial Race Among Top Roller Speed Skaters

    Okabe Fumitake, Takao Chiho, Fujita Zenya, Tsuchiya Jun

    International Journal of Sport and Health Science (Web)   17  2019

    J-GLOBAL

  • 女子やり投の投てき動作における日本トップ選手と世界トップレベル選手との比較

    田内健二, 遠藤俊典, 小林海, 藤田善也

    陸上競技研究紀要   5  2009

    J-GLOBAL

Awards

  • バイオメカニクス研究最優秀論文賞

    2016.09   日本バイオメカニクス学会   クロスカントリースキー競技のV2スケーティング走法中の滑走速度とスキー板に対する力の各軸方向成分との関係

    Winner: 藤田善也, 吉岡伸輔, 桜井義久, 石毛勇介

Research Projects

  • クロスカントリースキー競技における上肢と下肢による力の貢献度の走法間比較

    日本学術振興会  科学研究費助成事業

    Project Year :

    2018.04
    -
    2021.03
     

     View Summary

    本研究の目的は,力センサを内蔵したポールとスキーを独自に開発し,上肢および下肢で発揮される力の滑走速度への貢献度を走法間で比較することである.当該年度には,ポールとローラースキーから発揮される力の検出のためのセンサシステムの開発を実施した.センサスキーは,クラシカル種目用に新たに開発し,競技用ローラースキー(Alutech, Swenor)のフレームの底面にひずみゲージを貼付し,ローラースキーの底面へとかかる力を電圧の変化から検出できるようにした.さらに推進力となるローラースキーの水平方向へとかかる力を力センサ(9103A,Kistler)から検出できるようにした.これらのセンサから出力される電圧データは小型データロガーに取り込むことで,記録できるようにした.センサポールは1成分高感度力センサ(9217A, Kistler)をポールのグリップ部に内蔵し,ポールの圧縮方向の力を検出できるようにした.その際,ポールのたわみによる力の誤検出を防ぐために,先行研究をもとにテレスコープ式のシステムを構成した.先行研究で採用されているテレスコープ式のセンサシステムは検出精度が高く,ポール反力を高い精度で測定するために不可欠な構造である.しかしながらこれまで国内では同方式の検出システムの開発は行われておらず,また詳細なシステム構造も明らかにされていなかった.このシステムを当該年度内に開発できた意義は大きい.当該年度に実施されたセンサポールおよびセンサスキーの開発は,本研究の目的を達成するために不可欠なものであり,これらの開発が当該年度内に完了した点,新規性および検出精度の高いシステムを採用できた点において,高い実績を上げることができたといえる.当該年度内に計画していたセンサポールとセンサスキーの開発が完了していることから,研究はおおむね順調に進展しているといえる.特にセンサスキーにおいて,ひずみゲージと力センサの両方をシステム内に組み込むことはクロスカントリースキー競技を対象とした反力測定において新規的であり,これが完成したことは本研究において大きな進展であるといえる.今後は,開発されたセンサポールおよびセンサスキーを用いて,クロスカントリースキー滑走中のポールおよびローラースキーから発揮された力を収集し,各走法の特徴を明らかにする.さらにポール(上肢)とローラースキー(下肢)のそれぞれで発揮された力を走法間で比較することで,各走法の力学的特徴を明らかにする.クロスカントリースキー滑走中の力発揮特性の解明については,ヨーロッパを中心に研究が進められてきているため,当該分野の研究の進捗状況についてチェックをするとともに,新規性および独創性の高い研究成果を獲得していく

  • Biomechanical evaluation of the techniques of cross-country skiing

    Project Year :

    2014.04
    -
    2016.03
     

     View Summary

    In this study, the skiing techniques were evaluated using biomechanical analysis in cross-country skiing. It revealed that (1) the increase in the skiing velocity of V2 skating was associated with the rapid force exertion of pole and roller ski, (2) the skiing techniques of elite cross-country skiers in flat and downhill sections were superior to those of Japanese skiers, and (3) the time trial of double poling technique was useful in the evaluation of skiers’ performance

  • センシング技術を用いたクロスカントリースキー競技における滑走技術の検討 ~GNSS・慣性センサを用いたスケーティング走法の自動識別と評価~

    一般財団法人上月財団  第12回(2014年度)スポーツ研究助成事業

    Project Year :

    2014.04
    -
    2015.03
     

     View Summary

    クロスカントリースキー競技のスケーティング種目では,選手はコースの斜度や滑走速度に合わせて3種類のサブ走法 (V1スケーティング走法, V2スケーティング走法, V2オルタイネトスケーティング走法) を切り替えて滑走する.これらのサブ走法は,生理学的およびバイオメカニクス的観点でいくつかの違いが報告されており,選手は各サブ走法の利点を活かすことで,合理的に滑走速度を増加あるいは維持させていることが予想されるが,実際の滑走においてサブ走法の良し悪しとパフォーマンスとの関連を明らかにした研究は見当たらない.これらは,実際の滑走中の滑走速度の測定や,各サブ走法の評価方法が確立されていないためである.一方で,近年開発が進められている各種の小型センサを用いることにより,滑走中の速度や高度,選手の動きの同定が可能であることが明らかとなってきている.そこで本研究の目的は,全地球航法衛星システム (GNSS) と四肢に取り付けた慣性センサを用いて,クロスカントリースキー競技のスケーティング種目における3種類のサブ走法を自動識別し,滑走中のパフォーマンスを評価することとした.

    本研究では,(1)各サブ走法を自動で識別するためのプログラム開発とそのデータ取得のための実験,(2)開発されたプログラムを用いた評価実験の2つの実験を実施した.まず,1名の対象の両前腕およびローラースキーに慣性センサを取り付け,3種類のサブ走法中の角速度を記録した.記録された角速度の特徴をもとに各サブ走法を自動で識別するプログラムを開発した.次に自動識別プログラムの精度を評価するために,対象の胸部にビデオカメラを下向きに取り付け,実際に行ったサブ走法を記録した.対象の滑走速度および高度を評価するためにGNSSを対象に取り付け,滑走速度と高度を記録した.対象には,3.45 kmのローラースキー専用コースを最大努力で滑走させ,滑走中の各データを取得した.得られたデータに対して自動識別プログラムを実行し,識別結果を得た.自動識別プログラムによって得られた識別結果とビデオカメラから得られた結果より,プログラムの精度と正解率を算出した.

    その結果,開発された自動識別プログラムは,平均では92.3 %の高精度で各サブ走法を自動で識別できることが明らかとなった.また対象は,最大努力の滑走において,平地ではV2スケーティング走法あるいはV2オルタネイト走法が用い,上り坂では,V1スケーティング走法あるいはV2走法を用いることが明らかとなった.さらに,競技パフォーマンスの異なる2名の対象の滑走速度を比較したところ,コース前半の平地において,V2スケーティング走法中の滑走速度に違いがみられた.これらの結果より,競技パフォーマンスの低かった対象Bは,コース前半の平地において,V2スケーティング走法を用いて滑走速度をより高められるようなトレーニングを行うことが競技パフォーマンスの向上に寄与する可能性があることが示唆された.本研究によって開発された自動識別プログラムを用いることで,滑走速度と高度,サブ走法を対象ごとに比較することにより,競技パフォーマンスを高めるための具体的な方策を検討することが可能となった.

Presentations

  • 招待講演 富山県高等学校体育保健学会主催 「平成28年度富山県高等学校保健体育研究協議会」

    藤田善也  [Invited]

    平成28年度富山県高等学校保健体育研究協議会  (富山県)  富山県高等学校体育保健学会

    Presentation date: 2016.11

  • 招待講演 新潟県スキー連盟主催 「平成28年度クロスカントリー部コーチセミナー」

    藤田善也  [Invited]

    平成28年度(公財)新潟県スキー連盟クロスカントリー部コーチセミナー  (新潟県)  公益財団法人 新潟県スキー連盟

    Presentation date: 2016.07

  • 招待講演 青森県教育委員会主催 「平成27年度第2回トップ指導者招聘事業」

    藤田善也  [Invited]

    平成27年度第2回トップ指導者招聘事業  (北海道)  青森県教育委員会

    Presentation date: 2015.11

  • 招待講演 青森県教育委員会主催 「平成27年度第1回トップ指導者招聘事業」

    藤田善也  [Invited]

    平成27年度第1回トップ指導者招聘事業  (青森県)  青森県教育委員会

    Presentation date: 2015.08

Specific Research

  • 世界一流障がい者クロスカントリースキー選手のバイオメカニクス的分析

    2017  

     View Summary

    本研究の目的は,クロスカントリースキー競技を対象に(1)競技コースの詳細な距離および標高データを取得すること,(2)片腕に障害をもつ世界一流クロスカントリースキー選手のスプリント種目中の滑走速度および心拍数の変化を明らかにすることであった.(1)の目的を明らかにするために競技コース内に基地局を設置し,さらに被験者の頭部および背部にGNSSデータロガーを装着させて距離および標高データを取得した.その結果,従来は困難であった山間部でのミリ単位のデータ取得が可能であることが示唆された.(2)の目的を明らかにするために,競技中の滑走速度および心拍数を計測した.その結果,雪のコンディションによって滑走速度が変化すること,一流選手ではスプリント種目の決勝において最も高い心拍数で競技が行われることが示された.

  • バイオメカニクス的手法を用いた障がい者クロスカントリースキー競技の滑走技術の評価

    2016  

     View Summary

    片腕に障害をもつアスリートが行うサイクリックな運動を対象とした非対称性が運動の遂行に及ぼす影響に着目した研究は少ない.本研究の目的は,片腕に障害をもつクロスカントリースキー選手を対象に,滑走中のバイオメカニクス的特徴を明らかにすることであった.片腕に障害をもつ世界一流クロスカントリースキー選手を対象に上り坂におけるダイアゴナル走法中の動作分析を実施した.その結果,ポールを持つ側のプッシュオフ局面では滑走速度の立ち上がりが早いこと,同局面中の平均速度が高いこと,およびその後のグライド局面中の平均速度が高い傾向にあることが示唆された.

  • クロスカントリースキー競技における競技中の滑走動作と競技パフォーマンスとの関係

    2015   土屋 純

     View Summary

    本研究の目的は,クロスカントリースキー競技において,競技パフォーマンスの高い選手の優れた滑走動作を明らかにすることであった.対象となる滑走動作は第94回全日本スキー選手権男子15kmクラシカル競技における7.0km地点の上り坂のダイアゴナル走法とした.競技成績の上位9名の選手を上位群,上位群の所要時間より10%程度上回る所要時間であった10名を下位群とした.選手の滑走動作を分析した結果,競技パフォーマンスに優れた選手のダイアゴナル走法は,(1)滑走速度が高く,ストライド長が長い,(2)ポールプッシュ局面およびポールリカバリ局面の肘関節角度がより伸展位である,(3)スキー板接地前の足関節角度がより屈曲位であることが示された.

 

Syllabus

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Social Activities

  • 早稲田大学スキー部 助監督 兼 コーチ(クロスカントリー部門)

    2016.06
    -
     

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    2007- 早稲田大学スキー部 コーチ(クロスカントリー部門)

  • 特定非営利法人日本障がい者スキー連盟クロスカントリー委員会 フィジカルコーチ

    2015.04
    -