斜懸垂の力学

Static Model of Modified Pull-up

磨井 祥夫

桜井 佳世

広島大学総合科学部紀要. VI, 保健体育学研究

Memoirs of the Faculty of Integrated Arts and Sciences, Hiroshima University. VI, Studies in health and physical education

斜懸垂の上肢を伸展させた姿勢について力学モデルを作成し, 次のことを明らかにした。

「腕にかかる力の大きさ(T)は, ①重心の相対的高さ(x/b), ②体重(W), ③腕と胴のなす角度(β), ④腕と水平面のなす角度(α)の関数で表わされる。」

すなわち,

T = x/b • (cos(α-β))/sinβ • W

が成り立つ。

これらの変数のうち, ①, ②は個人の固有の値であり, ③, ④は姿勢によって変わる値である。筋持久力のテストでは, 全員の負荷を同じにする必要がある。同一負荷としては, 体重が最も簡便であると思われる。そこで, 負荷(T)として%体重を一定にするためには, ①, ③, ④を決定しなければならない。①については大学生女子でバラツキは小さい。また, ③は「腕と胴の角度を90°にする。」と決められているので, ④を規定すれば, 負荷をほぼ同一にすることができる。

Modified pull-up test is currently performed as a test of muscular endurance in females. But the measurements of this test, which reported by some universities, often have a large scatter in results. One of the reasons may be the difference of a posture in the modified pull-up. Then we built a static model and estimated the suspended force applied on both palms.

The suspended forse (T) is derived by the following expression.

T = x/b • (cos(α-β))/sinβ • W

where. W : body weight, x/b : relative position of CG, α: angle between upper limbs and the horizontal ground, β: angle between upper limbs and trunk.

It is found that the force(T) is the function of (x/b), W, α, and β.

There are variations in the value (x/b) and W between different subjects. In this sutdy the mean value of x/b is 58.6 %(SD = 1.5 %) for 34 female university students.

The angle α and β are, on the other hand, varied by the posture. When an accurate posture is made according to the manual, the angle β is fixed 90° and α is calculated to be 55.6 ± 1.5° in our subjects. Using the previous expression, the force(T) is made 33.0 ± 4.8 kgw, corresponding to 58.6 ± 1.5 % of individual body weight.

In practical testing, the angle β may be carefully followed to be 90°, however, the angle α has not been paied attention. With increasing the angle α, the greater force becomes applied to arms, and the performance of repetiton would be found to be reduced consequently.

In muscular endurance test, a constant work load, which is expressed by the ratio of body weight or maximal strength, should be applied to all subjects. Therefore, we concluded that the angle a should be described in the manual.

スポーツ・体育 [ 780 ]

日本語

広島大学総合科学部

Copyright (c) 1988 by Faculty of Integrated Arts and Sciences, Hiroshima University. All rights reserved.

[ISSN] 0289-3002

[NCID] AN10019090