Resisted Acceleration A-run

All sports have varying degrees and needs for acceleration. Yet, if we look across the spectrum of sports, we see vast similarities in mechanics. Watch Adrian Peterson taking a handoff and busting through the line, Everth Cabrera stealing a base, Wes Welker releasing off the line of scrimmage, Serena Williams sprinting to the net for a drop shot or Usain Bolt attacking out of the blocks on his way to break the 100 meter World Record. There are similarities how athletes accelerate regardless of the sport.

If we take a general overview of acceleration and a technical model of teaching, there are some glaring take-home messages from which athletes of all sports can benefit. 1) Produce more force in less time.  2) The recovery limb needs to recover through the “optimal range of motion”.  3) The force producing limb needs drive in the proper direction. However, all of these take-home messages differ from the sport being played to the position being played.

When we look at sprint mechanics, there are two definitive patterns. In acceleration, we have a piston-likeaction; during top-end speed it is more cyclical. There are also bridging mechanics called the ‘transition phase’ that are a hybrid of acceleration and top-end patterns. If we really narrow the lens of performance, we often see many athletes trying to cycle when they should be in a piston action. This can have two negative effects. One is a significant decrease in power. Second, athletes tend to slip, causing them to lose their footing because of the inappropriate pattern. With sports heavily dominant in acceleration, I spend a majority of my linear movement sessions dialing-in on the skill of acceleration.

I rely on acceleration partner runs to not only help educate my athletes on how to initiate and produce more forcestart position lean in less time, but more as a tool to teach proper direction of force application. This drill can be done with the Bullet Belt, Nike SPARQ resisted strap, a large towel or even with a partner applying resistance on shoulders from an anterior direction. Now, even though it is called a “resisted” A run, the purpose of the drill is for the resistor to apply enough resistance so the athlete can maintain an aggressive leaning body position (45-65% from the ground).

Set up: The lean will differ from each athlete for many reasons: Relative strength, postural integrity /concerns, coordination, skill acquisition and reliability of the resistance being held. I like to tell my athletes. “If you don’t start the drill in a good position, you typically won’t find it in the middle of the drill.”

Execution “punch”: From here I instruct the athlete to begin a punch action with the thigh (hip flexion) and avoid pulling the heel toward the rear end (knee flexion). This allows the athlete to create a “shank” of the femur and the tibia creating a greater force angle and puts the Gluteus Maximus on stretch in the loaded position (roughly 90 degrees). From a still shot view, we should see the lead shin parallel (with a dorsiflexed foot) to the rear leg and the torso . Now, we still make our goal about maintaining body position as opposed to pulling the person resisting us. Again, remember ‘joint position dictates muscle function’, and if we let pelvic or thoracic spine positions change (too great of hip flexion recovery can force the athlete to posterior tilt the pelvis or create too much thoracic spine flexion) the effectiveness of hip extension may be compromised.

emphasis left leg punch

Execution “drive”: Once the athlete has achieved the desired height of hip flexion, (again this will differ from each athlete based on height, leg length, and femur to tibia ratios and potentially restricted ROM. ), the intent now needs to “drive” back behind the hips while simultaneously punching the opposite thigh to the loaded position without changing body position. Our point of contact needs to be ball of foot and not the toes, because, if it is the toes, it will create an inappropriate loading pattern for the lower leg and minimize the effectiveness of hip extension.

emphasis left leg drive

Execution “arm drive”: The arms will follow a contralateral pattern with the legs.  The frontal plane view axis of motion will be from the glenohumeral joint. On the up swing, the elbow joint will be roughly 75 degrees, and the hand comes up to chin height. On the back swing, the elbow joint will roughly be 110 degrees, with the hand coming back to the hip. The reason for fluctuation of arm swing angle is to maximize the levers capability. A shorter lever moves faster around an axis, and a longer lever produces more force (torque) about an axis, in turn more bang for our buck with the arm action. Based on this, I teach my athletes to think about driving back with their arm action as opposed to reaching forward. In a sagittal plane view, I want my athletes to pretend there is a plane of glass bisecting left and right side down the mid-line of their body. From here, on upswing, the hand can touch the glass but it can’t cross over. On the backswing, the arm drives back into extension with slight abduction past the hip. This allows the athlete to take full advantage of the stretch reflex of the upper extremity.

arm swing front  arm swing side

Early on in the teaching progression, I will ensure that I allow enough recovery time for the athlete to be successful in the drill and allow for near-full ATP-PC recovery. Over the course of training, the skill will be refined, and from here, I will structure my volume based on sets and time. (Example 3 sets of 4 reps at 5-7 seconds of drilling with 90 seconds of recovery between reps and 3 minutes between sets.)

Now, this is merely just one drill in a series of micro progressions. In my opinion, the effectiveness of any speed workout is set with the foundation of technique.  Regardless of the sporting demand, acceleration is a necessary skill for the athlete. The real trick for the coach is how to teach the technical model of acceleration, while blending it into the needs and demands of the sport and the athlete.

 

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