Speed / Movement / Agility

Bone Growth and Youth Development


Adam Boily MS, MATJS, USAW

Here might be the most commonly asked question a strength & conditioning professional must answer to youth athlete parents.


“Will my 13 year old child (or younger or teenager) have a stunted growth from lifting weights?”


It depends. It depends if the athlete is exercising biomechanically correct or not. Stunted bone growth may occur when the open growth plates located at the ends of bones become damaged. Damaged open growth plates can happen for various reasons, which include an injury from sport or poor exercising technique. For example, if a 12 yo athlete playing soccer sustains a trauma to the knee in a soccer game, he/she could incur growth plate damage around the knee. Another way an athlete can sustain growth plate damage in the knee would be biomechanically incorrect weight-bearing exercises. Say a 10 yo athlete is front squatting and during every repetition their right knee caves in with a valgus moment. If an expert S&C coach is not there coaching the athlete out of these poor mechanics, overtime knee growth plate damage might occur before the plate close. However, most youth athletes will not experience growth plate damage from training or in sport as long as qualified professionals are monitoring exercises.

It’s important to develop youth athletes through sport and training participation because their young bodies and minds are like sponges and we want them to learn exercise technique and proper nutrition before they may learn bad habits. To avoid growth plate damage in young athletes, their training should be focused on light loads (body weight or light weights) so they can learn the intention of each exercise. When an athlete is below the age of 13 yo, they benefit tremendously from learning proper biomechanically correct exercise techniques and become strong through a long amount of isometric exercises. Before weight is increased for the youth athletes, volume and isometric times should be increased substantially so proper technique is reinforced and the athlete naturally performs exercises biomechanically correct. These exercises may include squatting, pressing, pulling, running, and jumping. Typically we find that athletes starting to exercise around 5-8 yo will become strong enough and biomechanically adequate for progressive resistance training when they reach 14 yo. Also, at this point, the growth plates are still open/undamaged and these athletes will start peak height velocity (puberty).

Surges of hormones, including testosterone, are beginning to flow through the athlete naturally. This is the ideal time for athletes to exercise with heavier resistance and advanced plyometrics. With the surge in hormones and advanced strength and conditioning volume combined, the athlete will experience hypertrophy of lean muscles, increased bone density, length, and girth as well as other bodily tissue growing. Sometimes, an athlete will grow rapidly and the muscles become stretch so fast that the brain has a hard time communicating to or controlling the muscles during this growth. In this case the athlete will become clumsy or uncoordinated (you may have this seen this with young basketball players). However, if during this time that same athlete were in a proper training program, especially involving isometric exercises (pillars or infant squats), their muscles would remain strong and would not become as clumsy. During this time of puberty, the athletes’ recovery time will be much more rapid allowing them to endure progressive amounts of volume from day to day and week to week.

To some it all up, participating in unsupervised training or with unqualified coaches could potentially put youth athletes in scenarios that could damage growth plates. Again, few youth athletes experience stunted growth and damaged growth plates and these rare occurrences from improper movements should not detour youth athletes from exercising young. The benefits a youth athlete receives from intelligent training and sport play are far too valuable to be passed up. There are many brilliant minds and a plethora of scientific research that shows bone growth will be improved (sometimes more than genetics had planned) rather than stunted through biomechanically sound youth training. Depriving a youth athlete from proper training before, during and after their peak height velocity is doing that athlete a major disservice and could potentially cause that athlete to never reach their full genetic potential.


*For more information join our BPSU and go research and study the work of Istvan Balyi (an expert in long term athlete development).


Any Running Back needs to be able to easily and fluently switch the ball from one arm to the next with ease. They also need to be able to stay low on change of directions, and change directions on a dime.

This drill first and foremost focuses on ball control. Note how our NFL RB clients Malcolm Agnew, Nick Hill, and Aaron Ripkowski moves throughout the drill. The ability to change hands is a trainable effect, and note how this drill forces the player to change arms efficiently.

The next focal point is staying low on changes of direction. Note with the cones as a target just focuses on bending at the knees with an upright torso position. This is a pure endurance drill that will train the muscles of the hips and legs in deep bending positions.

Finally, the changes of direction are sharp and crisp. Note the “positive” angles of the hips, where the emphasis is placed on the inside edge of the outside foot. This is essential to performance on the most difficult cuts a RB can make – specifically the “jump cut” that success is dictated by an athletes ability to get low and dip the inside shoulder – in almost the exact same angle as seen on each cone cut. The deceleration step off the outside edge of the inside leg sets up this hard change of direction off the outside leg. Perfect drill for utilizing both edges of the feet at extreme angles.

3 Rules for Youth Athlete Speed Development

Adam Boily MS, MATJS, USAW

3 Rules for Youth Athlete Speed Development

  • The Structure Rule

CAMPS – Before any training sessions, it is always important to have the structure of the training session outlined for maximal efficiency to maximize adaptations.  First, we need to increase the threshold ability of accepting and redirecting force for the ankles, knees, hips, trunk, and upper extremities.  This means, a well-designed CAMPS is vital for ensuring an athlete is prepared to execute the planned work for the day.  For example, start with SSP and progress from isometric modifications to full reflexive movements.  Once the base of support for the body is strong and tissue temperature is elevated, progress into SST that is skewed to prepare the muscles related to the planned movement or exercises of the day.

Application/Technical/Application – After an appropriate CAMPS muscle preparation, it’s recommended that the athlete begins the planned work with application first.  For instance, if the goal for the day is to increase the athletes ability to perform forward mutli-directional cuts (similar to a wide receiver in American football) we would begin by sprinting forward full speed then cutting diagonally at a 130* angle.  During the execution of the movement the coach can start to identify which aspect for the run and cut needs improvement from various vantage points.  After, 10-15 minutes of continuous application work, the coach can teach athletes a technical drill that is most appropriate for improving the application for the day.  For example, if more than 50% of the athletes in a group or training session are having issues executing an outside edge forward multi cut, the coach may elect to have the entire group perform the carioca quick step technical drill.  This drill is designed to overload the ground contact force on the outside edge of the foot and inside of the opposite foot.  Once the athlete has performed the drill 1-2 times correctly each direction, it is best to have the athletes finish the session with the same application forward cuts the sessions began with or progress to more difficult modifications of the forward multi movement.  A form of progressed forward multi cuts application could be visual and audible commands that force the athlete to cut based on an outside stimulus rather than a predetermined pattern.  If the most appropriate technical drill has been selected for a given group of athletes, more times than not, the second or final round of application work will be noticeably more efficient.  Progress the difficulty of the movement based on the athletes’ response overtime within the structure of application then technical work then application.

The end of the session can be sport specific by having the athletes sprint or do an application that closely resembles movement within their sport.  For example, a baseball shortstop player may choose to perform a sprint from a baseball-stealing stance.  Perhaps a tennis player will finish his or her session with lateral shuffles with change of direction to lateral shuffles.  Have a well planned structure and don’t stray to far from the planned volume of application work.

  • Technical Rule of Thumb

A very common technical drill utilized with BPS is our variations of the wall drill.  We chose either a linear wall drill, lateral wall drill, back lateral wall drill, etc.  It is typically progressed from isometric single switches to continuous reflexive rapid fire.  It is important that the younger youth athletes and/or beginners remain on isometric modifications.  For example, the isometric lateral wall drill is designed to overload and increased the foot’s abilities to accept and redirect force off of its inside and outside edges.  The fastest way to build a strong foundation of edge strength is to isometrically hold the lateral wall drill for 1-3 seconds facing each direction by switching the legs up and down 2-4 times.  Most growing youth athletes initially lack the strength in the edges of their feet and lack the truck stability necessary to expertly perform the lateral wall drill with reflexive rapid fire.  Technical drills should be performed only for a few reps during a given session since they are very taxing on the central nervous system.  Technical work is important for increasing thresholds for bodily structures and functions but must be supplemental to application work.  If technical work is consuming the majority of a given session, the benefits will not be realized during the application movements.  Technical drills are necessary to quickly improve application movements necessary for sport.  Always remember it is not appropriate to teach people how to form run with technical drills.  However, it is appropriate to improve movement efficiency by overloading and adapting muscle tissue.

  • Volume of Work Rule

Youth athletes require large amounts of volume.  An appropriate work to rest ratio should be around 1 to 2 or 1 to 1.  60-70% of a given session needs to be application work.  30-40% should be CAMPS, plyometrics, and technical work.  For example, on a backward multi-directional day, the first 10 minutes of the session should be specific CAMPS designed to prepare the body for backward multidirectional movements.  After a minute water break a good 10-minute plyometric routine should be completed and progressed based on skill level.  Again, a short water break may be given before the athletes start the first 15 – 20 minutes of application drills (i.e. back pedal or back angle pedals).  Chose between 2-3 appropriate technical drills while keeping in mind total technical work time should not exceed 10 minutes within this hour-long session.  Supper-setting 2 minutes of technical work with the application 3-4 times per session seems to elicit the best response for our youth athletes.  Finish the session on application for the last 15-20 minutes for a total of 30-40 minutes of application work during a given session.  Youth athletes respond and adapt well to large amounts of volume work since hormones are higher during that time of development.  Recovery and growth improvement opportunities are optimal if training structure, technical work, and volume levels are most appropriate.



When planning out a preparation for the movement/speed/conditioning session for the day, it’s always a good idea to include a good amount of exercises that is as specific to the patterns that will actually be performed.  In the Preparation section of Bommarito University, there are 4 primary sections for Preparation to be performed at the beginning of all sessions.  And the overall Preparation can be best described as CNS Activation and Muscle/Joint Preparation Systems (CAMPS):

  • Support System Preparation – primarily the “impact” joints of the toes, feet, and ankle
  • Trunk/Spine Preparation
  • Suspension / Support / Trunk (SST) Systems Preparation – focusing on the “link” between the Support and Trunk/Spine which is the suspension system through the hips, knees, and pelvis
  • Unloaded Speed/Movement Preparation

When focusing specifically on the SST Systems Preparation, notice there is an extremely large volume of exercise choices in the database for all 4 sections.  The 4 sections of the SST are:

  • General movement/muscle prep and tissue temperature elevation
  • Local joint isolation
  • Joint mobility/stability
  • CNS activation

The exercises listed on Bommarito University in the CAMPS section are just a sample of thousands of exercises that can be used for preparation.  There are over 150 individual sample exercises just in the SST section alone.  For an athlete to perform every single one of these exercises before a session would take well over an hour.  It’s a given that an hour-plus of preparation is definitely not needed for a session.  The big key question becomes how to choose which exercises on which days.  Some of it needs to be individualized to the client and the specific medical and/or biomechanical needs.  But some exercise selection can also match the specificity of the day.  Some basic examples are outlined below for each of the main movement categories.


The main focus for acceleration should be the full Support System Prep; and the SST System Prep that focuses on hip flexors, hip extensors, and hip separation.  An example of exercises out of the Bommarito Database for SST:

Section 1 – General Prep

    • Activation Prep – Buttkick Raise; Walking Knee Hug Lunge
      • Activation – Walking Lunge; Walking Extended Lunge – pause
        • Activation Prep – Rhythm March – SLOW PAUSE
          • Activation – Explosive Rhythm Lunges

Section 2 – Local Joint Isolation

    • Kneeling/Prone Hip Isolation Series
      • Kneeling Hip Extension – PAUSE and REFLEX
      • Prone Hip Extension – PAUSE and REFLEX
        • Supine Hip/Knee Series
          • Straight (opp leg bent) – PAUSE and REFLEX
          • Bent Straight (opp leg bent) – PAUSE and REFLEX
          • Bent Medial (opp leg bent) – PAUSE and REFLEX

Section 3 – Joint Mobility/Stability

    • Kneeling/Prone Hip Mobility Series
      • Kneeling hip extension/out – PAUSE and REFLEX
      • Kneeling hip extension/rotate/out – REFLEX
      • Prone extension/out – PAUSE
        • Pushup Hip Series
          • Knee Drives
          • Knee Drive Switches

Section 4

    • Back Reach Run – half speed, ¾ speed, full speed
      • Linear Wall drills – singles, triples, rapid fire sprint (from Linear Acceleration script)


Absolute speed, or maximum velocity, is obviously very similar to acceleration in the sense that it is movement in a straight line.  However, because it is moving at much greater speeds, and the leg is moving in more of a cyclical pattern (as opposed to the piston action of acceleration), the body must be prepared for these varying forces.

The Support System Prep through the foot/ankle joints will be similar, but just in lower volumes as compared to acceleration.  Instead of performing the entire sequence, probably just choosing two or three exercise sequences from this system is probably adequate.  Instead, the focus can be transferred more to the Trunk/Spine Preparation, which can make the absolute speed session much more efficient.

Trunk/Spine Preparation:

  • Alignment Position Band stabilization holds (from the right and left side) – since the athlete is set into a kneeling position with the hips separated, the force of the band coming from the right and the left side will emphasize the lateral flexors of the spine from an isometric standpoint while the pelvis is being stabilized in this split position
  • Forward Single Arm Sled March – the “heel dig and pull” action of the sled march will concentrically work the hip extensors.  While the force of the attachment of the sled is coming off of one side of the body (hence, the single arm position), the emphasis is being places on the rotators of the spine from an isometric standpoint as the hip is extending concentrically

SST Systems Preparation:

Section 1 – same as acceleration

Section 2 – same as acceleration

Section 3 – same as acceleration

Section 4 – now shift to more focus on absolute speed preparation

    • Ankling – half speed, ¾ speed, full speed
    • SL Stiff Leg Deadlift – PAUSE and REFLEX
    • Ankling to Buttkick – varying distances
    • Straight Leg March – SLOW PAUSE and FAST REFLEX
    • Straight Leg Skip – individual and continuous


A movement day involving patterns of lateral shuffle, lateral runs, and/or any forward multidirectional day will place a great deal of emphasis on heavy forces across the foot/ankle joints for changes of direction, and using a lot of hip adductors and abductors in various multidirectional runs and motions.

For the absorption of force and re-direction of forces for changes of direction, the entire Support System Preparation would be appropriate.  For the choices of exercises for SST System Preparation, the emphasis could be as follows:

Section 1 – General Preparation

    • Activation Prep
      • Hip Rotate (Glute) March – SLOW PAUSE and REFLEX
  • Activation
    • Hip Rotate (Glute) Skip – Rhythm individual and Power
  • Active Motion
    • Hip Rotate (Glute) Raise
      • Activation
        • Adduction Rhythm – varying speeds
  • Active Motion
    • Lateral Lunge – ROLL FOOT
    • Explosive Lateral Lunge – ROLL FOOT
      • Activation
        • Sumo Squat
  • Active Motion
    • Sumo Squat-outs

Section 2 – Local Joint Isolation

    • Side Lying Hip Series
      • Side Raise – PAUSE and REFLEX
        • Side Lying Hip Series
          • 30-deg Adductor Raise – PAUSE and REFLEX
          • 60-deg Adductor Raise – PAUSE and REFLEX
            • Supine Hip/Knee Series
              • Lateral – rotate out (opp leg bent) – PAUSE and REFLEX
              • Medial – rotate in (opp leg bent) – PAUSE and REFLEX

Section 3 – Joint Mobility/Stability

    • Standing Trunk Series
      • Trunk/Hip Rotations – SLOW and FAST
        • Standing Hip Series
          • SL Isometric ¼ Squat – front extension – slow
          • SL Isometric ¼ Squat – side extension – slow
          • SL Isometric ¼ Squat – side extension – slow

Section 4 – CNS Activation

    • Leg Swing Series
      • Linear – PAUSE and REFLEX
      • Lateral – PAUSE and REFLEX
        • Lateral Wall Drills – doubles (from Lateral Movement script)
        • Lateral Line Bounding – singles (from Lateral Plyometric script)


For a backward multidirectional emphasis, whether it is a backward run or a backpedal/anglepedal weave motion, will be really focusing on hip pivots.  Analyzing hip pivots from a biomechanical standpoint, it’s obvious that a lot of hip horizontal adduction and hip horizontal abduction occurs.   The preparation systems can then be emphasized with these two primary motions.  Just like with lateral and forward multidirectional, changes of direction will place a heavy emphasis on the Support System Preparation (for the foot/ankle joints).  However, one main difference is when executing the Support System Prep for backward emphasis days, the main focus should be on two exercise sequences from this database – Back Dorsiflex Series and Back Low Walk Series.  Instead of performing the entire Support System Preparation on the backward days, it might be more appropriate to just focus on multiple reps of just the Back Dorsiflex and Back Low Walk series.

For the SST Systems Prep, the following sequences have proven to be very appropriate for backward emphasis days:

Section 1 – General Preparation

    • Activation Prep
      • Back Pivot March – SLOW PAUSE and FAST REFLEX
  • Activation
    • Back Pivot Skip – rhythm individual, rhythm continuous, power
  • Active Motion
    • Drop Lunge, Explosive Drop Lunge, Explosive Drop Lunge-pause
      • Activation
        • Adduction Rhythm – varying speeds
  • Active Motion
    • In Place Lateral Lunge – FEET INVERTED
    • Lateral Shifts – FEET INVERTED

Section 2 – Local Joint Isolation

    • Kneeling/Prone Hip Isolation Series
      • Kneeling Side Lift – PAUSE and REFLEX
        • Side Lying Hip Series
          • Side Glute Raise – PAUSE and REFLEX
            • Side Lying Hip Series
              • Adductor Raise – PAUSE and REFLEX

Section 3 – Joint Mobility/Stability

    • Lying Trunk Series
      • Supine Crossovers – PAUSE and REFLEX
      • Prone Crossovers – PAUSE and REFLEX
  • Kneeling Trunk Series
    • Alignment Thoracic Rotation – PAUSE and REFLEX
      • Standing Hip Series
        • SL Squat Touchdown – PAUSE and REFLEX

Section 4 – CNS Activation

    • Leg Swing Series
      • Forward/Backward Circles – SLOW and FAST
        • Back Lunge Series (from Backpedal/Anglepedal script)
          • All 6 levels

As with any preparation for any movement script, the Unloaded Speed/Movement Prep can be a good substitution and change of pace.  However, for the concept of specificity, the exact scripts listed above can really be an efficient way to progress the forces required for the exact movements seen in the training.  Many example and variations of exercises can be substituted, but the main concepts can always be implemented for optimum performance.  To summarize:


  • Full Support System Prep
  • SST Systems emphasis on hip flexors/extensors
    • CNS Activation emphasis on re-directing force


  • Short, quick Support System Prep
  • Heavy emphasis on Trunk/Spine Prep
  • SST Systems emphasis on hip flexors/extensors
    • CNS Activation emphasis on technical mechanics of absolute speed and heavy emphasis on eccentric loading


  • Full Support System Prep
  • SST Systems emphasis on hip abductors/adductors and trunk stability
    • CNS Activation emphasis on dynamic hip mobility and low-grade plyometrics of absorbing forces through the edges of the feet


  • Support System Prep heavy emphasis on forces in a backward pattern (Back Dorsiflex and Back Low Walk Series)
  • SST Systems emphasis on hip horizontal adductors and hip horizontal abductors and trunk mobility
    • CNS Activation emphasis on dynamic hip mobility and force absorption and re-direction in low, deep-bending positions