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Leg extension power in heavyweight elite judo athletes
Takeru SATO 1
Keisuke MIYAKE 5
15

Hiroyuki AKIMOTO 2

Kenji KAWABATA 6

Hiroshi KUBOTA 7

23Kogakkan University

Chukyo University

Toshihiro TAKEZAWA 3

6

Ryotokuji Gakuen

Hokuriku University

7

Takayuki YOKOYAMA 4

Katsuyuki MASUCHI 8

Kanto Gakuen University

Gifu University

84Atsuo KASUGAI 9

Setsunan University

University of Tsukuba

9Meiji University

INTRODUCTION
It is well known that mental fortitude, technique, and physical strength are the factors that contribute tocompetitiveness in sports. In judo, these factors are sometimes referred to as “shin-gi-tai,” literally meaning “mind,skill, and body,” which are essential elements in competition. Physical strength in particular affects competitiveness.
Improving functional elements, particularly physical strength, is necessary for increasing competitiveness. Leg
strength is particularly important in many competitive sports, and evidence from a study that observed leg extension
during judo throwing techniques indicates 2) that leg extension power likely influences the success of judo techniques.
In judo tournaments, athletes must throw their opponent quickly and with force to earn a high score for theirthrowing technique. Therefore, it is considered that extending the legs quickly and forcefully while performing athrow has an advantage in judo. For example, leg extension is observed in “flipping” movements where athletes
extend their lower leg while they support themselves on one leg with their knees flexed and throw an opponent
during an uchi-mata. It is also observed in the rapid extension of both legs while throwing an opponent over theshoulder during a seoi-nage. Thus, leg extension is considered to play an important role in both of these movements.
Furthermore, because judo practitioners must also react quickly to their opponent’s moves and maintain their posture
to avoid being thrown, leg extension power is another important factor in maintaining posture and balance, while
being attacked by an opponent. Based on these observations, it is logical to assume that an athlete must have a very
high skill level to become an elite judoka.
PURPOSEThis study compared the leg extension power of elite Japanese heavyweight male judoka with that of elite
Japanese lightweight male judoka, and clarified the exhibited characteristics.
METHODS
Eleven All Japan Judo Federation certified heavyweight male judoka and 12 All Japan Judo Federation certified
lightweight male judoka were analyzed. The Aneropress 3500 1) (Combi Wellness, Tokyo, Japan) was used in thisstudy because it measures leg extension power through movements similar to the knee extension movements in judo
throwing techniques. In addition, it allows measurements to be easily gathered while teaching. The measured items
included leg extension power, height, weight, body fat percentage, lean body mass, thigh circumference, and crus
circumference. A risk ratio of less than 5% was considered statistically significant (P < 0.05).
2500

Leg extension power (W)RESULTS
The average leg extension power values were
2169.0 ± 165.5 W and 2105.0 ± 73.9 W for theheavyweight judoka and lightweight judoka,
respectively, with the average value for theheavyweight judoka being higher, albeit notsignificantly (Fig. 1). However, significantly higher
height, weight, body fat percentage, lean body mass,
thigh circumference, and crus circumference values
were recorded in the heavyweight judoka (P < 0.01)(Table 1).

2000
1500
1000
5000
Elite heavyweight judo athletes

Elite lightweight judo athletesFig. 1 Comparison of leg extension power between elite heavyweight
and lightweight judo athletes－ 13 －DISCUSSIONFirst, we can easily infer that leg extension power is closely related to leg muscle mass. Significant differenceswere observed between the study groups for body weight, LBM, and thigh and crus circumferences. This indicates alarge discrepancy in muscle mass between heavyweight and lightweight elite judoka.
Table 1 Physical characteristics of the athletes in each group
Height（cm）

Weight（㎏）%Fat（%）

LBM（㎏）

Age（yrs.）

Experience（yrs.）

Heavyweight elite
judoka group（n＝11）

181.4 ± 2.1

117.4 ± 4.6

24.2 ± 1.2

88.6 ± 2.7

25.3 ± 1.2

16.9 ± 1.4

Lightweight elite
judoka group（n＝12）

166.8 ± 0.9****
71.3 ± 1.2**
14.0 ± 0.4**
61.2 ± 0.9*
22.1 ± 0.7

16.3 ± 0.9

Right thigh
Left thighRight crus
Left cruscircumferences circumferences circumferences circumferences
（cm）
（cm）
（cm）
（cm）
Heavyweight elite
judoka group（n＝11）

68.0 ± 1.4

Lightweight elite
judoka group（n＝12）

55.3 ± 1.1

67.5 ± 1.2**

45.2 ± 0.7**
54.8 ± 1.2

45.1 ± 0.7**
37.3 ± 0.5**
37.2 ± 0.4（Average ± SD）* ： P ＜ 0.05， ** ： P ＜ 0.01

Next, we observed no difference in leg extension power between heavyweight and lightweight elite judoka. This
indicates that even though heavyweight elite judoka have considerably more muscle mass and are much stronger thanlightweight elite judoka, heavyweight elite judoka do not exhibit their leg extension power to the maximum. In otherwords, lightweight elite judoka exercise leg extension power more efficiently than heavyweight elite judoka. These
results also suggest that a lack of leg extension power may have a negative impact on the performance for current
Japanese heavyweight judoka. Compared with lightweight judoka, heavyweight judoka more often compete against
opponents who are heavier than they are, and leg extension power should naturally be more important forheavyweight judoka than lightweight judoka. Nevertheless, the heavyweight elite judoka measured in this study did
not have the same leg extension power as the lightweight counterpart. This also indicates that the top Japanese
heavyweight judoka do not have sufficient leg extension power to throw an opponent with a similar build while
supporting their own weight.
CONCLUSION
These results clarify that while the heavyweight judoka had superior physical characteristics, such as greater leanbody mass and thigh circumference, there was little difference in leg extension power between the heavyweight andlightweight judoka. Furthermore, there is an urgent need to develop specialized training equipment that can enhance
leg extension power and to establish training methods that can more effectively improve leg extension power forheavyweight elite judoka.
REFERENCES
1) Ito, M. and Yoda, Y., Development of an apparatus to measure instantaneous leg extension power output, J. J.
Sports Sci., 11, 742-746, 1992.
2) Ishi, T., Kanamaru, Y., Ae, M., Okada, O., and Komata, K., Tai-sabaki and the body position in Seoi-nage,
Bulletin of the Association for the Scientific Studies on Judo, Kodokan, 13, 87-96, 2011.
3) Sato, T., Relationships between leg extension power and Judo competitive ability in elite judoka, Report of theFaculty of Education, Kogakkan University, 5, 35-42, 2013.
4) Sato, T., Akimoto, H., Takezawa, T., Yokoyama, T., Miyake, K., Masuchi, K., and Kasugai, A., Evaluating
judoka leg extension power: Comparing leading and student judoka using the Aneropress 3500, Bulletin of theAssociation for the Scientific Studies on Judo, Kodokan, 14, 81-87, 2013.

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