Specific Flexibility In The Hurdles
By Gunter Tidow, Germany
The statement that specific flexibility is a must for
high hurdlers is probably accepted by everyone (cf. Gambetta & Hill
1981; Bush 1984; Pereversjov, et al. 1984 ). The question, however, as to
what degree of flexibility is needed precisely could---up to now---only be
answered subjectively by analyzing the movement behavior of world class
Doing so it is quite obvious that within the split phase (Fig. 1) the knee flexors of the lead leg as well as the hip flexors of the trail leg are highly stretched. On the other hand, within the bar clearance (Fig. 2, F) and especially within the preparation for landing phase (Fig. 2, G), considerable specific flexibility of the abductors of the bent trail leg is indispensable.
Whereas corresponding range of motion in the respective joints is a prerequisite for hurdle specialists, conditions are sometimes quite different with decathletes and sports students. Apart from this, even certain flaws of top hurdlers might be traced back to flexibility deficiencies. This is why in my opinion a testing apparatus was needed to assess hurdle-specific flexibility and to make available set values that flexibility training can be directed to.
The Abduction Test is performed as follows (Fig. 4). After making sure
that the subject remains in a vertical posture and having fixed his trail foot
to the T bar by means of a belt, he is asked to raise his bent and abducted
trail leg as high as possible and to hold the end position for at least 2 sec. A
test result of 97, for instance, indicates that the inner part of the ankle was
97cm above ground. Dividing 97 by the leg length (e.g., I00 cm) which was
measured before hand by means of the hurdle-fleximeter, too---the "AI," i.e.,
the "Abduction Index," can be computed. An index of .97 implies that the subject
has raised his ankle up to a level equal to 97% of his leg
To perform the Split Test the hurdle-fleximeter has to be rearranged in the following way (Fig. 5):At first the T -bar is fixed at 3ft. 6in., i.e., at high hurdle bar level. Then, a tape measure, that is kept in a permanent stretched state by means of a counter weight is connected with a little platform the subject is standing on. The subject is asked to place his lead leg heel on the T-bar and to grip his lead leg shank near the ankle with his counter arm (Fig. 6). For stability/safety reasons the other hand should glide along a bar parallel to the extended lead leg. Finally, the tester controls the advance of the wheeled fleximeter while the subject increases the spreading distance between supporting and leading foot by shifting body weight in the direction of the latter (Fig. 6).
When the spread maximum is attained, the tester can read the corresponding result on the tape measure immediately. The tape glides over one of the two rollers connected to the T-bar, thus in plain view of the tester.
The "Split Index" (SI) is calculated by dividing the test result of, for instance, 190cm by double-leg length (including the additional "lift" caused by the plantar flexion of the trail foot). Thus an SI of .85 indicates that 85% of the anthropometrically limited distances has been attained.
Comparison between body positions during the tests with the corresponding phases of the hurdle strides how the main requirements of the tests mentioned above have been fulfilled, at least to a certain degree (Fig. 7 and Fig. 8).
In all, 100 male subjects took part in the tests: the (national) best 51 junior decathletes, 44 sports students and 5 high hurdlers, among them the FRG (West German) champions (youth and men).
The main results are presented in Table 1.
As could be expected, the specific flexibility of high hurdlers was far superior in both tests. This is why their arithmetic means functioned as "set values" to assess stretching capacities of the other groups. The (average) results of the best junior decathletes and of the sports students did not differ significantly.
While the arithmetic means--representing central tendencies--given in Table 1 may appear to be acceptable, they tend to "conceal" individual val- ues. These individual results may be either advantageous or limiting to the high hurdle technique. The identification of individual flexibility deficiencies was, of course, the main objective of the tests introduced here.
A comparatively low correlation of .62 between ST and AT results imply that flexibility is not a general ability. This is why we suggest that Grosser's Hurdle Sit Table Test (HSTf), which was also performed (but only by the sports students) and which correlated far more closely with the Split Test (r=.75) than with the Abduction Test (r=.41), should be applied primarily when there is lack of time or for a more complex assessment. For differential diagnosis either ST and AT should be performed separately.
Referring to technique the following consequences can be derived from
limited specific flexibility:
1. Poor Split Test Results:
Due to the fact that the m. biceps femoris is a two-joint muscle, the hurdle attack phase cannot be executed properly: An accentuated shift (forward lean) of the upper body-with an erect spinal chord-would cause the lead leg knee to bend. Consequently a flat trajectory is pre- vented-otherwise the foot of the lead leg would collide with the bar.
If insufficient spreading abilities are caused by shortened hip flexors, e.g. m. iliopsoas, the pushing leg cannot take over its "trailing function" within the spread phase. Thus its knee is not-as it should be-well be- hind the trunk, but far too early beneath the hip joint. Consequently the deliberately delayed but (then) smooth and dynamic action of the trail leg is hampered or even destroyed.
A further negative effect of limited spreading abilities is the reduction or even prevention of producing a slight forward rotational impulse around the lateral axis, needed for a quick touchdown after clearing the hurdle.
2. Poor Abduction Test Results:
That limited abducting abilities (in an indirect way) affect the flight curve negatively is known to everyone. This applies especially to the "hurdle sit phase" (or bar clearance phase).
In addition a lack of abducting abilities prevents the hurdler from compensating for the active downward movement of the lead leg after clearing the hurdle by a reactive forward- upward action of the trail leg. Thus, the needed forward lean of the upper body cannot be sustained.
Furthermore poor abduction capacities prevent the pelvis axis from tilting (or slanting) towards the side of the lead leg. The tilt elongates the length of the lead leg. Thus it can contact the ground earlier. Apart from this the tilt provides a buffer-capacity for a smoother compensation to the impact when landing.
Finally a higher-than-average abducting flexibility enables the athlete to preserve a high level of the CG within the landing phase. Consequently the contact time as well as the landing load of the supporting leg are reduced. Thus the first stride of the inter-hurdle sprint can be performed staying tall with a high knee lead.
Bush,J.(1984):Hurdles-Technique andTraining.1984 US Olympic Trials Clinic. University of South. Calif., L.A.
Gambetta. V., Hill. D. (1981): Hurdling. In: Gambetta, V. (Ed.): Track and Field Coaching Manual. West Point.N.Y.:72-78.
Grosser. M. ( 1972). Die Zweckgymnastik des Leichtathleten. Schorndorf.
Pereversjov, E., Tabatchnik. B., Chalilov. v. (1984): Zur Erfasung von Talenten im Hiirdenlauf. In: DLV-Lehrbeilage 110:15-22.
Tidow. G. (1983). Wege zur Leistungsdiagnostk und Talentselektion im Mehrkampf-Dargestellt am Beispiel derDL V -Zehnkampf- Testbatterie 1982. In. DLV.Lehrbeilage 48:19-26; 49: 21-24.