This document provides a biomechanical assessment and return to sport plan for an athlete who underwent an ACL reconstruction. Kinetic and kinematic testing found some asymmetries during jumping that suggest compensation from the hip and ankle. A multi-stage progression plan was created collaboratively involving a coach, physical therapist, and physician. The plan focuses on neurovascular, strength, and power development through integrated stabilization exercises and progressive agility drills. Future assessment ideas and strategies to address muscle compliance and bracing are discussed to optimize the athlete's return.

1. B I O M E C H A N I C A L C O N S I D E R A T I O N S
F O R A C L R E T U R N T O S P O R T
JOSH BULLOCK, MA, MAM, RSCC *D
NOVEMBER 4th
,2023

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T H A N K Y O U
NSCA & UNLV
WESTMINSTER, CSP, & IHC
ATHLETES
MENTORS & COLLABORATORS
MY TEAM AT WU

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C O N F L I C T
In the past, I was a contract
writer for Teambuildr.
I am currently a Teambuildr
customer.
I currently serve as a
consultant for IHC and will
complete my dissertation in
the lab at TOSH.

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B R I E F
01. Assessment
Case Study
02.
Work Samples
03.
Ideas
Intervention
Future

5. JOURNEY

6. A S S E S S M E N T
A CASE STUDY

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T H E A T H L E T E
DOS: 8/18
TIMELINE
MOGUL
SKIER
Anterior Cruciate Ligament
RTT: 6/19
RTC: 12/19
Left Knee

8. M O G U L S K I I N G

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F O R C E P L A T E S
ISOM 90
ISOM 75
SQUAT JUMP
COUNTERMOVEMENT JUMP
80:20
PURPOSE
TESTS
KINETIC CHARACTERISTICS
SUMMATION OF GRFs

10. 1.35
4
6.5
4
0 1 2 3 4 5 6 7
9-Jul-20
13-Jan-20
12-Sep-19
9-May-19
Peak Force Percent Symmetry
I S O M E T R I C
B E L T S Q U A T
* Positive number denotes right side heavy.
Data was captured at 90 degrees of knee flexion.

11. -4.525
-0.675
-6.025
-0.813
-2.913
-7 -6 -5 -4 -3 -2 -1 0
Take-Off PeakForce
Phase One Concentric Impulse
Phase Two Concentric Impulse
Concentric Mean Force
Concentric RFD
Percent Symmetry
S Q U A T J U M P
* Positive number denotes right side heavy.
The athlete starts at 90 degrees of knee flexion.

12. 0.475
0.771
-0.5
-2.235
-4.275
0.56
0
-5 -4 -3 -2 -1 0 1 2
Eccentric PeakForce
Concentric Peak Force
Eccentric Impulse
Phase One Impulse
Phase Two Impulse
Eccentric Braking Impulse
Concentric RFD
Percent Symmetry
C O U N T E R M O V E M E N T
J U M P
* Positive number denotes right side heavy.
The athlete performs a countermovement prior to jumping

13. W E ’ R E G O O D
10% ASYMMETRY THRESHOLD
ANY RED FLAGS?
ATHLETE STATUS
90% CAPACITY THRESHOLD
PAIN FREE
NO OBERVABLE DYNAMIC VALGUS
FULL PARTICIPANT

14. T O S H
TOSH – The Orthopedic Specialty Hospital in Murray, Utah, is Intermountain Healthcare’s home for comprehensive orthopedic
healthcare and sports medicine excellence. Since 1991, they have served patients and athletes throughout Utah with a wide range
of orthopedic specialties and services—all at one campus.
TOSH features Intermountain Sports Medicine and Sports Performance services. They treat sports-related injuries, help athletes
prevent sports-related injuries, identify and improve areas of weakness, create custom training and nutrition plans, and elevate all
levels of athleticism.

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R E S U L T S

16. T H E U N S E E N
What presents itself as Phase 1
Concentric Impulse Symmetry is a
significant effort by the left hip to make
up for the lack of work performed at the
knee.
We see a similar compensation in Phase
2 with a similar effort at the ankle.
When taken in summation, all appears
well.
Not Visually Observable!
STATIC (SQUAT) JUMP

17. QUAD & HAM
RATIO
KNEE & HIP
JOINT KINETICS
RANGE
OF MOTION
DYNAMIC
VALGUS
PAIN
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T H E B I G S I X
KINESIOPHOBIA

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D O E S I T M A T T E R ?
WHICH IS BETTER
THE NEW MOTOR PATTERN
THE ORIGINAL MOTOR PATTERN
ONGOING DISCOURSE

19. ACLR patients show differentiated trunk, hip, and knee kinematics
during vertical hops more than 20 years post-injury.
Biomechanical deficits are associated with cartilage degeneration three
years following anterior cruciate ligament reconstruction
Biomechanical analysis has identified movement differences between
those who experience a subsequent ACL rupture and those who do
not. Athletes with a prior rupture are 15-25x more likely to re-tear.
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W H Y T H E O G ?
2-20 YEARS
POST -OP
INCREASED
RISK OF
REINJURY
DEGENERATIVE
ISSUES

20. I N T E R V E N T I O N
WORK SAMPLES

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U N D E R
P I N N I N G S

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E I P v s . E B P
01. Research
Peer-reviewed literature.
02. Your knowledge, skills, and
abilities.
03. Practical contact with and
observation of facts or events.
Expertise
Experience

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E C O L O G I C A L
D Y N A M I C S
Under an ecological dynamics framework,
athletes and sports teams are considered
complex adaptive systems. Additionally,
proponents of an ecological dynamics
framework view learning to occur by
continuously solving movement problems
and not performing repetition habitual.
DYNAMICAL SYSTEMS THEORY

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C O N T I N U U M S

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M U S C L E S L A C K
COMPLIANCE (+EMD)
Stretch ability of the SEE and CE.
STIFFNESS
The greater the stretch, the stiffer SEE and CE.
Pretension through co-contraction
• Cocontraction before joint motion results in the uptake of slack
from the MTU. Once aligned, some compliance is overcome.
Countermovement
• CE lengthens during slow/submaximal jumps
• CE works isometrically/concentrically during fast/maximal jumps
External load
• Adding external load may increase stiffness and hinder the
development of proper pretension through cocontraction.

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H A R D W A R E
CAPABILITIES
The neurophysiological adaptations/responses
occurring ahead of skill expression.
CAPACITY
The outward expression of skill inventory
and the ability to express it with tolerance.

27. POSITION
PATTERN
POWER
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T H E 3 P ’ S

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A P P L I C A T I O N

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I N T E G R A T E D C A R E
01. Planning Document
02. Spearheaded
Eight Stage Progression
Collaboratively Created
Kasey Janes – W&P Coach – RTS Specialist
Monica Atherton – Physical Therapist

30. R A C I
There are many stakeholders, either directly or indirectly, involved in and
affected by the outcome of the RTS process. Establishing roles, responsibilities,
scopes of practice, and identifying the key transition points of the team
involved throughout an athlete’s return is critical to an effective and efficient
process.
Stage 00 Stage 01 Stage 02 Stage 03 Stage 04 Stage 05 Stage 06A Stage 06B Stage 07 Stage 08
AD PT MD HSC
PT/AT
AD
MPC
RD
MD
HSC
ATHLETE

31. 0
2
0
1
0
3
0
4
0
6
0
5
0
7
0
8
GSI
INJURY ILLNESS KINEMATIC KINETIC CAPACITY
CONDITION ANTHROPOMETRIC KINETIC ASYMMETRY
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D E C I S I O N

32. INTEGRATED
STABILIZATION STABILIZATION
EQUIVALENT
MUSCULAR
DEVELOPMENT ABSOLUTE
STRENGTH
60%-70%
4-2-0
2-4/WEEK
CORRECTIVE
EXERCISE
40%-60%
4-2-0
1-5/WEEK
75%-85%
2-0-0
2-4/WEEK
70%-80%
2-1-0 (STR) or 3-2-1 (STAB)
2-4/WEEK
75%-95%
0-0-0
1-3/WEEK
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N E U R O M U S C U L A R
T R A I N I N G
ELASTIC
EQUIVALENT
75%-95% (STR) or 35%-80%( PWR)
0-0-0
1-3/WEEK
MAXIMAL
POWER
25%-55%
0-0-0
1-3/WEEK

33. P R O G R E S S I O N S
AUTOMATED SYSTEMS
LOCOMOTOR PROGRESSION
SQUAT PATTERN PROGRESSION
QUAD/HAMSTRING PROGRESSION
PLYOMETRIC PROGRESSION

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R E C O N D I T I O N I N G
STAGE 00-02 WELL BODY RECONDITIONING ONLY
• UBE
• SL CYCLING
STAGE 03 & 04 CYCLE-BASED RECONDITIONING
STAGE 05 CYCLE- & GROUND-BASED RECONDITIONING
HEART RATE BIOFEEDBACK
STAGE 06+ GROUND-BASED RECONDITIONING
LIMB SYMMETRY BIOFEEDBACK

35. F U T U R E
IDEAS

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A S S E S S M E N T
TESTING MAY INCLUDE
Quad dominant ISOM test
Single and Multiple Response
Bilateral, Unilateral, Cyclical
Acceleration, deceleration, & COD
Blended data sets
Single Case Experimental Design

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H I P S T R A T E G Y
OFF-LOADING TO THE HIP
If possible, never let it start
Block for the hips
Early AD may require a stricter task constraints
Target/guide for the knee
PNF posterior chain in induce inhibition
Pre-fatigue and well-body for the posterior chain
EMS to potentiate or support quad function

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M U S C L E S L A C K
OPTIONS FOR COMPLIANCE:STIFFNESS
Slower surf of the F-V curve
Slower JT progression & exploration of take-off/landing/range/speed
Accentuated or accommodating resistance and VB biofeedback
Utilization of plio, mio, and coupled methods
Return to low threshold work as JT intensifies or volume increases
Changes in surface type use to decrease GRF’s and CE stress
Decreased Kinesiophobia
Locomotor (GAIT) progression forcing a tall and extended hip position
Loaded locomotor training

39. B R A C I N G A N D
B I O F E E D B A C K
THEY ARE OUT OF THE BOOT; FOR NOW….
Foot and ankle complex kinetics and kinematics
System-Wide RTS
Expanded biofeedback force/power symmetry
Strategic Bracing
Compared to healthy individuals, those with ACL reconstruction
walked with 78% more hamstring impulse and 19% less
quadriceps impulse. The functional knee brace produced an
additional 43% increase in hamstring impulse and an additional
13% decrease in quadriceps impulse in the ACL group.

40. T H A N K S
QUESTIONS?

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R E F E R E N C E S
CONTACT
JOSH BULLOCK
801.707.9809
JOSH.B.BULLOCK@GMAIL.COM
WWW.JOSHBULLOCK.ORG