The A-skip in running drills: hop twice on one leg, drive the other knee with a tight knee angle and tap. Build-up, milestones, mistakes and safety hints.
The honest answer up front: in the A-skip you hop twice on one leg while the other is lifted with a tight knee angle and then taps the ground. That is how the running-drill collection of the Swiss Federal Office of Sport (BASPO) with Swiss Athletics describes it: in the A-skip the knee angle stays tight during the knee lift, like an "A" [1]. In plain words: it is a coordination puzzle for head and legs, with knee lift, rhythm and landing under the body.
What is it for? The source names an economical, energy-saving running technique and coordination as the goal [1]. Whether the A-skip makes you measurably faster has not been studied; there is no study on the individual drills. What research does support is the principle behind it: in a study of 14 runners, braking forces rose when the foot landed farther in front of the hip [4]. The exercise collection therefore stresses foot strike "under the center of mass" [3]. That does not mean "heel" or "ball". It is about where the foot lands, not which part of the foot. Read this guide after skipping sits.
Where do you use the A-skip? In the warm-up before speed sessions, after ankle drill and skipping, as the third exercise in the series. Two passes are enough. More at this stage brings frustration rather than technique.
How hard is it? The sequence feels complicated at first. In experience terms you need several sessions until the rhythm runs automatically. The names of the skip family (A, B, C) are interpreted slightly differently by coaches; here the BASPO description applies.
Stand on one leg and hop twice while the other leg carries the rhythm. Count "hop-hop, tap". Milestone: 10 clean repetitions per side while standing.
Lift the free knee so the angle stays tight [1]. The leg forms an "A". Practice tip: let the lower leg hang relaxed under the knee instead of pushing it forward. The torso stays upright.
After the two hops, the foot of the lifted leg taps the ground [1]. Then you switch sides. The tap is short, not heavy.
Move forward slowly. The foot lands under the body [3], the arms swing loosely along. Milestone: 20 meters without a rhythm break.
After 20 to 30 meters you walk or jog back easily, 2 to 3 repetitions [2]. Raise the pace only when the rhythm sits at slow speed [2].
Film yourself from the side and pause at the moment of the tap. Is the shin of the stance leg roughly vertical, and does the foot land about under the hip? Then you are on track. Lieberman and colleagues found that landing with a relatively vertical shin at the end of the swing phase was favorable [4]. As a runner you do not have to measure it, but you can see it on video. Then compare two recordings from different weeks and look at just one thing, such as the landing spot. One improvement per week is enough.
A double hop on one leg while the other is lifted with a tight knee angle and then taps [1].
In the A-skip the knee angle stays tight, in the B-skip the leg is extended explosively forward after the knee lift [1].
BASPO recommends 10 to 20 minutes of running drills per session, 20 to 30 meters per exercise and 2 to 3 repetitions [2].
When skipping sits. BASPO advises starting with simple exercises and building harder ones slowly [2].
B-Skip: Extend the Leg Forward and Pull It Back Actively