A kinematic comparison of the running of A and B drills with sprinting

Expert Discussion Biomechanics and Physiology
1

A KINEMATIC COMPARISON OF THE RUNNING A AND B DRILLS
WITH SPRINTING

KIVI, D.M.R. and ALEXANDER, M.J.L
Faculty of Physical Education and Recreation Studies
University of Manitoba, Winnipeg, MB

INTRODUCTION
The running A and B drills are two drills which are frequently used by sprinters during training. The present study was a kinematic analysis of these drills, with comparisons to sprinting. The rationale for this study was that no biomechanical studies have been completed comparing these or any other sprint training drills to the biomechanics of sprinting.

REVIEW AND THEORY
Drills are a key component of a sprinter’s training program. According to McFarlane (1994), skill development in sprinters involves performing specific drills which isolate and combine joints to rehearse a series of movements that establish exact motor pathways. There are two drills which sprinters perform regularly during training, the running A drill and the running B drill. The running A drill may be described as a marching action performed at a running pace, where the legs alternate from a position of support to a position of hip and knee flexion. In support, the hip and knee should be fully extended with the ankle plantarflexed. Following support there is a simultaneous and rapid flexion of the hip and knee, where the thigh is brought to horizontal and the foot is brought up to the buttocks with the ankle dorsiflexed. Next, the hip and knee rapidly extend, and the ankle plantarflexes for ground contact. The mechanics of the upper body should resemble those of sprinting, with a slight forward body lean and a vigorous arm action with the elbows flexed to approximately 900. The running B drill is similar initially to the running A drill with rapid hip and knee flexion, but instead of simultaneous hip and knee extension, the knee extends prior to hip extension. The result is a movement of the foot in a circular path in front to a position under the body for support. The mechanics of the upper body should resemble those of sprinting. Various track and field articles (McFarlane, 1994; Lopez, 1995) and books (Carr, 1991; Bowerman & Freeman, 1991) advocate the use of the running A and B drills in sprint training. There is no scientific documentation, however, describing or analyzing the biomechanics of these drills, nor is there any comparison of the biomechanics of these drills to the biomechanics of sprinting. The purpose of this study was to examine the kinematics of the running A and B drills, and to compare them to sprinting. Because the drills are used extensively in training, the hypothesis for this study was that no differences in the majority of the kinematic variables would exist among the running A drill, running B drill, and sprinting.

PROCEDURES
A group of university level sprinters were recruited, 4 males (mean age = 21yrs, mean 100m pb = 10.79sec) and 4 females (mean age = 23yrs, mean 100m pb = 11.98sec). A seven metre filming grid was located on the straight of a 400m mondo track. Through this grid, the subjects completed four repetitions of both the running A and B drills, followed by two runs of 60 metres at maximum velocity. Two genlocked cameras filmed in the sagittal and frontal views at a speed of 60 Hz, with a shutter speed of 1/2000. A three dimensional model of the performance was reconstructed via DLT using the Peak Performance Technologies motion analysis system. Twenty-three kinematic variables describing performance were analyzed. Data was smoothed using a Fast Fourier Transform filter, with cut-off frequencies from 4 to 8 Hz and were controlled for points across all subjects. Three consecutive steps from one trial were analyzed, beginning with contact of the right foot. The peak values for each of the three steps were averaged to give one representative value used for analysis. A one-way analysis of variance was used to determine if significant differences existed among the three skills. Post hoc tests were used to determine where the differences existed. Level of significance for all tests was (p < 0.05).

RESULTS AND DISCUSSION
Both vertical displacement and vertical velocity were larger for sprinting than for the A and B drills. Step frequency was found to be greatest for the A drill, followed by sprinting and the B drill. Support time was shortest for sprinting, while non-support time was shortest for the A drill. Shoulder range of motion was found to be significantly greater for sprinting, as was shoulder flexion angular velocity. No significant differences in shoulder extension angular velocity were seen among the three skills. Elbow range of motion and elbow extension angular velocity were similar for all three skills, but elbow extension angular velocity was found to be significantly slower in the B drill. Sprinting produced greater range of motion values for trunk flexion, trunk rotation, and pelvic rotation. At the hip, maximum hip flexion was greater for the A and B drills than for sprinting. Hip flexion angular velocity was similar in all three skills, while hip extension angular velocity was greatest for sprinting. There were no differences in knee range of motion. Sprinting produced greater knee angular velocities than the drills in both the flexion and extension directions. Ankle range of motion, plantarflexion angular velocity, and dorsiflexion angular velocity were significantly greater for sprinting. Differences among the three skills were seen in the timing of peak angular velocity at the shoulder, hip and knee through the sprint stride. Differences among the three skills were also seen in the angle at which peak angular velocity occurred in the shoulder and ankle joint ranges of motion. Angle-angle diagrams outline the differences in the simultaneous movements of the right hip and knee during one cycle of each of the three skills. Angle angle diagrams for the A drill, B drill, and sprinting for subject 3 are seen in Figures 1, 2, and 3.

Figure 1: Angle-angle diagram for the right hip and knee during the A drill for subject 3.

Figure 2 : Angle-angle diagram for the right hip and knee during the B drill for subject 3.

Figure 3 : Angle-angle diagram for the right hip and knee during sprinting for subject 3.

The following events are outlined on each diagram: IFS = ipsilateral foot strike, ITO = ipsilateral toe-off, CFS = contralateral footstrike, CTO = contralateral toe-off. From the results of this study, it was concluded that the kinematics of the A and B drills were not similar to sprinting. Coaches must be aware of these differences when incorporating the A and B drills into a sprinter’s training program. Future studies on the biomechanics of sprint training are necessary.

REFERENCES
Bowerman, et al. High Performance Training for Track and Field (2nd Ed.). Champaign: Leisure Press, 1991.

Carr, G.A. Fundamentals of Track and Field. Champaign: Leisure Press, 1991.

Lopez, V. Track and Field Coaches Review, 95(1), 16-20, 1995.

McFarlane, B. Track Technique, 126, 4016-4020, 1994

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A and B drills are similar to downhill runs or resistance runs in that the
biomechanics differs from sprinting. Given the critism of resistance/downhill runs on this basis it is fair to reason that A and B drills can also disrupt a sprinters firing patterns and biomechanics.

From the above study the following data was noted

1)“Shoulder range of motion was found to be significantly greater for sprinting, as was shoulder flexion angular velocity”

2)“Support time was shortest for sprinting, while non-support time was shortest for the A drill”

3)" elbow extension angular velocity was found to be significantly slower in the B drill."

4)"Sprinting produced greater range of motion values for trunk flexion, trunk rotation, and pelvic rotation. At the hip, maximum hip flexion was greater for the A and B drills than for sprinting. "

5)“Sprinting produced greater knee angular velocities than the drills in both the flexion and extension directions. Ankle range of motion, plantarflexion angular velocity, and dorsiflexion angular velocity were significantly greater for sprinting.”

6)“Differences among the three skills were seen in the timing of peak angular velocity at the shoulder, hip and knee through the sprint stride. Differences among the three skills were also seen in the angle at which peak angular velocity occurred in the shoulder and ankle joint ranges of motion”

Increased contact time occurs in A & B drills with shorter swing time. Other then disrupting support phase mechanics the hip and shoulder range is restricted

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Great find Sharmer.
I don’t think there are any drills that can truly keep to sprinting form, because the interaction of all the body mechanics used in the running motion just can’t be replicated. It’s all about finding the drills that are most able to assist in training the body to respond “correctly” when at full flight.

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Drills are part of the process of learning and rehearsing certain movement patterns.
A few thoughts about the study. There is such a wide range of skill levels of those doing the drills- wider even than the skill range of sprinting itself. So whose in the study? Also drills are so often messed up by the search for multiple uses. LIKE EVERYTHING drills must be learned at a rate slow enough that they can be done right first. Then the rate can be increased to the point at which perfect form can still be maintained. Otherwise you get a dog’s breakfast.

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I don’t think there are any drills that can truly keep to sprinting form, because the interaction of all the body mechanics used in the running motion just can’t be replicated

Exactly, drills disrupt firing patterns since they are biomechanicly different then sprinting. A and B drills both increase contact time which negatively effects sprint technique. Often Coaches have beliefs about sprint mechanics that they are unwilling to discard despite evidence to the contrary. It is part of learning process of a coach to overcome such misconceptions

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Sharmer,

Are you saying to discard drills? How do they increase ground contact time?

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How do they increase ground contact time?

The swing leg accelerates back/down at a slower velocity thus causing the foot to strike lower and increasing CT. Think of the leg as a pendulum the slower it swings down/back the lower the foot strikes delaying CT.

A more scientific explanation is by reducing GRF , F=MA since the acceleration component is reduced CT is increased. A decrease in ground forces increases the bodys inertia during support.

Are you saying to discard drills?

That question is not for me to answer all i try to do is provide facts. Its up to individual coaches to make that decision.

Theirs a fine line between sports scientistic and coach.

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But you haven’t provided all the facts. Only the negative ones.

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Absolutely anything that is not a 100meter sprint will be done differantly than a 100meter sprint. For most, even a 30meter sprint will be done at a differant leval of tension, as will a 20meter fly-in. We’ve seen 60meter sprint races where somebody comes second who in an outdoor 100 meters would be leading at 60 meters! Anything that is not a 100meter sprint is not 100% spacific to a 100 meter sprint.
It would seem that the more something works on a particular component, the less spacific it is.
e.g, back squats build strength but have even more ground contact time than jump squats, which have more ground contact time than plyometrics, which often have more ground contact time than running drills, which have more ground contact time than sprinting, which has more ground contact time than flying. Is it not obvious that running drills will have differant shoulder/arm extension velocity/ angle thingy hip etc, than sprinting? Just by doing or watching the drills we should all be able to understand this. I know it’s not all about ground contact time as to what is spacific etc, but I think you get the point of what I’m saying.
I think one of the fun areas of sprint preperation is deciding to what degree along the sprint spacific V’s singular component curves you want to direct your attention. I put it to the forum that one of the biggest influances on sprint speed is not spacific and has a gound contact time average of 7 to 8 hours, e.g sleep.
I also know that kickboxing is not spacific to sprinting but one month I went along to a few sessions, and my sprinting instantly became more free with better posture and relaxation. I could go on, but no more need.

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Even though ground contact time in drills is longer than in sprinting,
most sprint drills would not increase the ground contact time (for your normal sprinting) if the relevant limbs are APROACHING the gound at the APROPPRIATE angles. Even if the drill/exercise has much greater ground contact time than sprinting because of less energy and speed application than in sprinting.

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Was this finding published or is it in press? Do you have the reference handy.

Thanks a very interesting post.

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It’s very well argeed that the only way to train for sprinting is sprinting itself. It would be interesting to find out exactly where these drills came from and first started being used. My theory is that they originated from marching drills that were focused on teaching technique to incapable athletes. Even a modest athletic talent should be skipping by first grade. As far as I know it, humans are the only mammal that can take something so easy to understand and make it confusing as hell…lol.

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That’s hilarious!

I think many athletes/coaches hold the misconception that sprinting technique can be developed through the monotonous repetition of drills. When in reality sprint technique is determined largely by physiological parameters. Muscular power and strength are the key ingredients to good technique

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The entire dissertation can be downloaded from http://mspace.lib.umanitoba.ca/handle/1993/1215

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I will never believe the a’s and b’s drills are bad to use or useless, they have greatly worked for me and are used by every world class sprinter, unless someone can prove to me its not :rolleyes:

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i believe the guys who produce results on the track

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Ya, i mean talk is talk, what gets you results is whats matters.

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For me drills work in a different way by giving you the kinesthetic feeling of positions and providing some specific strengthening exercises. I also think they are overrated for improving technique par se but they are useful. It’s like in Pole Vault where you use giants on a high bar to work on timing and rhythm for inversion but it is completely different to on the pole. Still from doing it myself I think it really helps you to begin to learn the proprioception required to master such a complex skill. If nothing else it improves confidence!

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With respect to the time and effort taken to perform the study and the useful measurements that were taken…

Doesn’t this study just affirm what we already knew?

I don’t think anyone here was under the impression that he who performs the drills most efficiently, or the most rapidly, will secure his place in the finals of the A category of the 100m this year at the big show.

nor do I think that anyone here was under the impression that if their athletes demonstrated high efficiency in the drills they would also demonstrate kinematic sprinting excellence.

Of course if I am incorrect on one or both counts than I suspect that those coaches who thought otherwise experienced a paradigm shift in their thinking after reviewing the findings and now have a host of things to think about in terms of what it takes to develop world class speed.

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Yes. Drills are useful but different. for example good As have the foot under ther knee throughout while there is step-over in the sprints. this is where the jerks came in to re-interpret what Mach had in mind- as if he couldn’t speak for himself. likewise, drills, like jumps etc have their own rythem to optimise a shortened GCT. The more you rush them the worse the GCT becomes.