12/13/2016
The University of North
Carolina at Chapel Hill
Sports Medicine Research Laboratory
Integration of Recovery Science into Rehabilitation
and Return to Play Following Knee Injury
Darin A. Padua, PhD, ATC
Professor & Chair, Exercise & Sport Science
Director, Sports Medicine Research Laboratory
Overview
• Many ways recovery science may improve outcomes following ACL
reconstruction (ACLR)
• Focus on 2 key areas:
1. Muscle strength deficits
2. Training load management upon return to sport (RTS)
Orthopaedic Summit 2016 – Evolving Techniques
Las Vegas, NV
December 7-10, 2016
Restoring quadriceps strength is a major challenge
following ACLR
Muscle Mass is Strongly Associated With Strength Following ACLR
Quadriceps Muscle Strength Factors
• 10% to 20% deficit in quadriceps strength persist for years
following ACLR
• Vastus Int. CSA  r = 0.86
• Vastus Med. CSA  r = 0.67
Elmqvist et al, 1989; Feller & Webster, 2003; Anderson et al, 2002; Bach et al,
1994; Rosenberg et al, 1992; Williams et al, 2004; Kuence et al, 2015; Thomas
et al, 2013
• Vastus Lat. CSA  r = 0.47
• Persistent weakness linked to:
–
–
–
–
• Vastus Int. CSA  R2 = .725
Poor patient reported outcomes Kuenze et al, 2015
Altered movement patterns Lewek et al, 2002
Decreased functional performance Dunn et al, 2010
Possible OA development Tourville et al, 2014; Oiestad et al, 2010
• Vastus Int + Med CSA  R2 = .756
• No association between CSA and CAR measures
 Muscle mass is critical for restoring strength
Kuenze et al, J Ortho Res, 2016
Regulation of Skeletal Muscle Mass:
Protein Synthesis vs. Protein Degradation
How to optimize the effects of exercise on muscle mass development?
Exercise
Maintenance
• Protein Synthesis = Protein Degradation
Leg Press
Squats
Atrophy
• Protein Degradation & Protein Synthesis
• Protein Degradation > Protein Synthesis
Hypertrophy
• Protein Degradation & Protein Synthesis
• Protein Synthesis > Protein Degradation
Knee
Extension
 Muscle Mass
1
12/13/2016
How to optimize the effects of exercise on muscle mass development?
Exercise
How to optimize the effects of exercise on muscle mass development?
Exercise
Nutrition
Nutrition
Leg Press
Leg Press
Squats
Squats
Knee
Extension
 Muscle Mass
 Muscle Mass
Protein Supplementation & Muscle Strength
• 33 untrained men (19-25 years)
• 3 Groups:
– SUPPLEMENT: 20 g whey protein + 6.2 g leucine + resistance training
– PLACEBO: 26.2 g maltodextrin + resistance training
– CONTROL: no supplement or resistance training
– SUPPLEMENT or PLACEBO was taken 30 minutes before and immediately
after each training session
%Increase in Quadriceps Strength
Protein Supplementation & Muscle Strength
• Design: randomized, double-blinded, placebo-controlled
35
30
*
Trained Limb
20
*
15
• SUPP > PL
5
0
%Increase in CSA
%Increase in CSA
40.6% greater increase in
Trained Limb
CON
*Increased relative to CON
Coburn et al, J Str Cond Res, 2006
• 30 individuals ~1.5 years post-ACLR
Untrained Limb
PL
PL
PRO & CHO Supplementation in ACLR Patients
Protein Supplementation & Muscle Mass (CSA)
SUPP
• SUPP =  in
Trained and
Untrained Limb
• PL =  in Trained
Limb
10
Coburn et al, J Str Cond Res, 2006
Trained Limb
Untrained Limb
*
25
SUPP
7
6
5
4
3
2
1
0
Protein
Synthesis &
Degradation
Knee
Extension
• 12 week strength training program
7
6
5
4
3
2
1
0
– 3x week (leg press, leg curl, squats)
• Supplementation (immediately post-exercise)
– PRO+CHO (10g protein & 7g carbohydrate from skim milk)
– CHO (17g carbohydrate)
SUPP
PL
– PLACEBO
56.3% greater increase in
Untrained Limb
Coburn et al, J Str Cond Res, 2006
Holm et al, J Orthop Res, 2006
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12/13/2016
Recommendations to Maximize Muscle Mass Following ACL Injury
PRO & CHO Supplementation in ACLR
16
14
*
• Focused nutrition should start immediately after injury
% Change Strength
% Change CSA
16
14
12
12
10
10
8
8
6
6
4
4
2
2
0
*
– Increased metabolic demands for healing requires adequate nutrients
– Minimize Atrophy ( protein degradation,  protein synthesis)
• Increase PRO intake before and after rehabilitation
– Rehabilitation is training
– Need increased protein intake for muscle mass development (protein
synthesis > protein degradation)
0
PRO + CHO
CHO
PL
PRO + CHO
CHO
PL
30% greater muscle CSA and strength in the PRO+CHO vs CHO only
• Focus on “clean” proteins (animal product or whey protein supplement)
• Proper nutrition maximizes the benefits of exercise
Holm et al, J Orthop Res, 2006
30% suffered knee re-injury following return to level 1 sports
After Return to Sport (RTS)
• 45.5% of knee re-injuries sustained
within 2 months following RTS
Are patients ready for increased
training load upon RTS?
Have patients experienced enough
training load to tolerate RTS?
Acute to Chronic Training Load “Spikes” and Injury Likelihood
• Acute to Chronic Load
Spike = >1.5
– Acute = Past 1week
– Chronic = Past 4 weeks
• 53% of injury likelihood
variance in following week
is explained by acute to
chronic load ratio
25
Likelihood of Injury (%)
Knee Re-Injuries Following ACLR  Return to Load Mismanagement?
20
15
10
5
1.00
1.50
Acute to Chronic Load Ratio
.00
Grindem et al, Br J Sports Med, 2016
Daily Load
Duration (min)
Total distance (miles)
Avg (SD)
75 (26)
3.8 (1.14)
High speed distance (miles)
0.15 (0.14)
Heart Rate Max (%)
65.7 (5.7)
Session RPE (0-10 scale)
4.7 (2.5)
Malone et al, Int J Sports Physiol Perform, 2015
Blanch & Gabbett, Br J Sports Med, 2015
Likelihood of Injury (%) Based on Acute to Chronic Load Ratio
Projected Acute Load at RTS
7.6 miles / week
• 4 practices + 1 game during week
19 miles / week
• 6.25 training hours / week
• 19 miles / week
• 0.75 miles high speed running / week
Consider the individual’s chronic load at
time of RTS?
(4 weeks prior to RTS)
Actual Chronic Load
Normal Avg. Chronic Load
40% of normal
avg. chronic load
Chronic Load
(% of normal average)
Training Loads in Soccer
2.00
110
4.7
4.1
3.6
3.4
3.2
3.3
3.5
100
4.3
3.7
3.4
3.3
3.3
3.6
4.0
90
3.9
3.5
3.3
3.3
3.6
4.2
4.9
80
3.5
3.3
3.3
3.7
4.3
5.3
6.6
70
3.3
3.3
3.7
4.6
5.8
7.5
9.5
60
3.3
3.8
4.9
6.6
8.8
11.6
14.9
50
4.0
5.5
7.9
11.0
14.9
19.6
25.1
40
6.6
10.1
14.9
20.9
28.2
36.7
46.5
30
14.9
23.2
33.7
46.5
61.4
78.6
98.0
60
70
80
90
100
110
120
Acute Load
(% of normal average)
Blanch & Gabbett, Br J Sports Med, 2015
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12/13/2016
Likelihood of Injury (%) Based on Acute to Chronic Load Ratio
Actual Acute Load
Normal Avg. Acute Load
100% of normal
avg. acute load
110
4.7
4.1
3.6
3.4
3.2
3.3
3.5
Unrestricted Return to Load
110
4.7
4.1
3.6
3.4
3.2
3.3
3.5
100
4.3
3.7
3.4
3.3
3.3
3.6
4.0
100
4.3
3.7
3.4
3.3
3.3
3.6
4.0
90
3.9
3.5
3.3
3.3
3.6
4.2
4.9
• Acute load = 100% of
normal average at RTS
90
3.9
3.5
3.3
3.3
3.6
4.2
4.9
80
3.5
3.3
3.3
3.7
4.3
5.3
6.6
80
3.5
3.3
3.3
3.7
4.3
5.3
6.6
70
3.3
3.3
3.7
4.6
5.8
7.5
9.5
70
3.3
3.3
3.7
4.6
5.8
7.5
9.5
60
3.3
3.8
4.9
6.6
8.8
11.6
14.9
60
3.3
3.8
4.9
6.6
8.8
11.6
14.9
50
4.0
5.5
7.9
11.0
14.9
19.6
25.1
– Hard intensity (RPE = 5)
50
4.0
5.5
7.9
11.0
14.9
19.6
25.1
40
6.6
10.1
14.9
20.9
28.2
36.7
46.5
– 7.6 miles / wk
40
6.6
10.1
14.9
20.9
28.2
28.2 36.7
46.5
30
14.9
23.2
33.7
46.5
61.4
78.6
98.0
30
14.9
23.2
33.7
46.5
61.4
78.6
98.0
60
70
80
90
100
110
120
60
70
80
90
100
110
120
• 40% chronic load at RTS
– 2.5 training hrs / wk
Chronic Load
(% of normal average)
19 miles / week
Chronic Load
(% of normal average)
19 miles / week
Likelihood of Injury (%) Based on Acute to Chronic Load Ratio
Acute Load
(% of normal average)
Acute Load
(% of normal average)
Blanch & Gabbett, Br J Sports Med, 2015
Return to Load Progression:  Acute Load by 1.45 x Chronic Load
Blanch & Gabbett, Br J Sports Med, 2015
Return to Load Progression:  Acute Load by 1.45 x Chronic Load
4.7
4.1
3.6
3.4
3.2
3.3
3.5
Week 2
110
4.7
4.1
3.6
3.4
3.2
3.3
3.5
100
4.3
3.7
3.4
3.3
3.3
3.6
4.0
• Acute Load (65%)
100
4.3
3.7
3.4
3.3
3.3
3.6
4.0
90
3.9
3.5
3.3
3.3
3.6
4.2
4.9
90
3.9
3.5
3.3
3.3
3.6
4.2
4.9
80
3.5
3.3
3.3
3.7
4.3
5.3
6.6
80
3.5
3.3
3.3
3.7
4.3
5.3
6.6
70
3.3
3.3
3.7
4.6
5.8
7.5
9.5
70
3.3
3.3
3.7
4.6
5.8
7.5
9.5
60
3.3
3.8
4.9
6.6
8.8
11.6
14.9
60
3.3
3.8
4.9
6.6
8.8
11.6
14.9
50
4.0
5.5
7.9
11.0
14.9
19.6
25.1
40
6.6
10.1
14.9
20.9
28.2
36.7
46.5
30
14.9
23.2
33.7
46.5
61.4
78.6
98.0
60
70
80
90
100
110
120
– 3.6 training hrs / wk
– 11.0 miles / wk
• Chronic Load (40%)
– 2.5 training hrs / wk
– 7.6 miles / wk
– 4.0 training hrs / wk
– 12.2 miles / wk
• Chronic Load (45%)
50
4.0
5.5
7.9
11.0
14.9
19.6
25.1
6.6
6.6
– 2.8 training hrs / wk
40
10.1
14.9
20.9
28.2
36.7
46.5
30
14.9
23.2
33.7
46.5
61.4
78.6
98.0
– 8.5 miles / wk
60
70
80
90
100
110
120
Chronic Load
(% of normal average)
110
• Acute Load (58%)
Chronic Load
(% of normal average)
Week 1
4 to 10
Acute Load
(% of normal average)
Acute Load
(% of normal average)
Blanch & Gabbett, Br J Sports Med, 2015
Return to Load Progression:  Acute Load by 1.45 x Chronic Load
Blanch & Gabbett, Br J Sports Med, 2015
Return to Load Progression:  Acute Load by 1.45 x Chronic Load
4.7
4.1
3.6
3.4
3.2
3.3
3.5
Week 5
110
4.7
4.1
3.6
3.4
3.2
3.3
3.5
100
4.3
3.7
3.4
3.3
3.3
3.6
4.0
• Acute Load (100%)
100
4.3
3.7
3.4
3.3
3.3
3.6
4.0
90
3.9
3.5
3.3
3.3
3.6
4.2
4.9
90
3.9
3.5
3.3
3.3
3.6
4.2
4.9
80
3.5
3.3
3.3
3.7
4.3
5.3
6.6
80
3.5
3.3
3.3
3.7
4.3
5.3
6.6
70
3.3
3.3
3.7
4.6
5.8
5.8
7.5
9.5
70
3.3
3.3
3.7
4.6
5.8
5.8
7.5
9.5
60
3.3
3.8
4.9
6.6
8.8
11.6
14.9
60
3.3
3.8
4.9
6.6
8.8
11.6
14.9
50
4.0
5.5
7.9
11.0
14.9
19.6
25.1
50
4.0
5.5
7.9
11.0
14.9
19.6
25.1
40
6.6
10.1
14.9
20.9
28.2
36.7
46.5
40
6.6
10.1
14.9
20.9
28.2
36.7
46.5
30
14.9
23.2
33.7
46.5
61.4
78.6
98.0
30
14.9
23.2
33.7
46.5
61.4
78.6
98.0
60
70
80
90
100
110
120
60
70
80
90
100
110
120
– 6.2 training hrs / wk
– 19.0 miles / wk
• Chronic Load (69%)
– 4.3 training hrs / wk
– 13.1 miles / wk
Acute Load
(% of normal average)
Blanch & Gabbett, Br J Sports Med, 2015
– 6.2 training hrs / wk
– 19.0 miles / wk
Successful
progression of loading
to typical demands of
training & games
Chronic Load
(% of normal average)
110
• Acute Load (100%)
Chronic Load
(% of normal average)
Week 5
Acute Load
(% of normal average)
Blanch & Gabbett, Br J Sports Med, 2015
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12/13/2016
Key Points
Recommendations for Systematically Increasing Load Until Full RTS
• Monitor training load the month before RTS
– Wearable technology or RPE
• Understand loading demands required upon full RTS (no restrictions)
• Do not increase acute load no more than 1.45x over chronic load
– ~10% increase each week
• Proper nutrition + exercise may minimize muscle mass and strength
deficits following ACLR
– Maintain caloric intake and adequate amounts of PRO
– PRO prior to and following rehabilitation (training)
• Systematic increase of acute training load may be critical for safe RTS
following ACLR
– Avoid “spikes” in acute load upon return to sport
– Do not increase acute load (1 wk) more than 1.5x above chronic load (4 wk)
– Acute to Chronic Load Ratio < 1.5  minimize injury risk
– Incrementally increase acute load until matching the load demands of full
participation in sport / activity
• Continue to increase acute load until meeting the loading demands of
sport
Exercise and Nutrition Impact Genetic Expression
(-)
Exercise
+
CHO
 Proteolytic
Gene Expression
 Protein
Degradation
Muscle
Hypertrophy or
Maintenance

Regain or
Minimize Loss
of Function
Exercise
and/or
Nutrition
Protein + Kcals
Thank You
Darin A. Padua, PhD, ATC
[email protected]
Exercise
+
CHO & PRO
 Anabolic
Gene Expression
(+)
Conclusions
 Protein
Synthesis
Greenhaff PL. The molecular physiology of human limb
immobilization and rehabilitation. Exer Sport Sci Rev, 2006
Genes Regulate Skeletal Muscle Mass
• Consuming an anabolic meal before and after training may improve
exercise benefits:
 Proteolytic
Gene Expression
– Increased muscle size (CSA and volume)
 Protein
Degradation
– Increased muscle strength
– Improvements are greater in both the trained and untrained limb
• Restoring muscle mass and strength with exercise is enhanced with
PRO + CHO supplementation in ACLR subjects
Coburn et al, J Str Cond Res, 2006; Holm et al, J Orthop Res, 2006
 Atrophy

 Strength
Immobilization /
Reduced Activity
 Anabolic
Gene Expression
 Protein
Synthesis
Greenhaff PL. The molecular physiology of human limb
immobilization and rehabilitation. Exer Sport Sci Rev, 2006
5