Transcript Adaptation of Quadriceps and Hamstring

Adaptation of Quadriceps and Hamstring Activation Patterns
Following Landing Instruction in Patients with ACL Reconstruction
Audrey RC Elias, DPT, OCS; Curt D Hammill, MS; Ryan L Mizner, PT, PhD
School of Physical Therapy and Rehabilitation Science, The University of Montana, Missoula, MT
Introduction
Methods
• More than 200,000 people undergo
anterior cruciate ligament (ACL)
reconstruction (ACLR) of the knee yearly
7 1;
• Risk of re-injury is 1 in 4 to 1 in
healthy athlete injury rate is 1 in 100 (female)
and 1 in 500 (male)
Dynamic Task Performance
• 5 minute treadmill walking warmup
• Single leg landing from 20 cm step
• 3-5 warm up trials
• 5 recorded trials before and after training session
• Motion Analysis, Force Plate, and EMG data collected with focus on
weight acceptance phase (contact to peak knee flexion)
• > 50% show evidence of early onset
osteoarthritis within 10 – 15 years1
Results
Performance Improvement with Training
• Significant improvement in all measures of performance
PRE
POST
VGRF
3.5 ± 0.39 BW
VGRF
3.07 ± 0.31 BW
Knee Angle
55° ± 11°
Knee Angle
78° ± 11°
• The ACLR knee is unable to accept weight
and attenuate force normally during high
demand activities
Average ± St.Dev; All Comparisons are significantly different p < 0.001
• Fortunately, these movement patterns
respond well to training2
• Well-established “optimal” landing strategies
Controversy over how optimal landing helps
Two Common Alternatives:
o Train for “co-contraction”3
• Use hamstrings at the same
time as quadriceps
• “Brace” the joint
o Train for selective contraction4
•  responsiveness of the joint
• Use quadriceps more than
hamstrings
What changes during training for optimal performance?
Purpose
To explore changes in activity patterns of the muscles
surrounding the knee during and after instruction for
improved knee performance in landing
Subjects
•
•
•
•
N = 36 (15 male, 21 female)
Mean age = 22.1 ± 4.45 years
Tegner Activity Scale = 7.03 ± 1.48
Surgery 26.4 ± 15.7 months prior
Inclusion Criteria
• Unilateral ACLR within 6 – 48 mos
Exclusion Criteria
• ≥ 3 ACL surgeries or bilateral ACLR
• Medical conditions that could limit
function in last 6 months
• <4 Tegner physical activity scale
Standard Training and Instruction
• 5 – 10 minutes of instruction and practice to adapt landing
• Visual demonstration and explanation of undesirable landing
• Followed by instruction and demonstration of desired landing
• Blocked practice with positive feedback for successful landing
“Try to land softly and quietly”
“Increase the bending in your knee and use your knee to absorb impact”
“Stay balanced over your feet and look straight ahead when you land”
Kinematic and Kinetic Analysis
3-Dimensional Motion Analysis
• 8-cameraVicon system (sampling: 200Hz, filtered:12 Hz)
• 14 mm reflective markers positioned as shown
Force Plates
• 2 force plates (sampling:1200 Hz, low pass filter: 50 Hz)
• Measuring Vertical Ground Reaction Force (VGRF)
Kin-Com Isokinetic Dynamometer
• Maximum Voluntary Isometric Contraction (MVIC)
• Both hamstring and quadriceps
Muscle Activation Analysis
Delsys Electromyography (EMG) System
• Surface EMG hamstrings and
qudriceps (sampling: 1200 Hz)
• Bandpass filtered: 20 – 350 Hz
• Full-wave rectified
• Low-pass filtered: 12 Hz
• Linear envelope normalized to MVIC
• Co-activation index (CI) between hamstrings
and quadriceps integrated over interval
50 ms pre-land to peak knee bending
CI = (EMGless / EMGmore) + (EMGless + EMGmore)5
EMGless = activation level of less active muscle
EMGmore = activation level of more active muscle
• Muscle CI  significantly
• Pre-training: 30.4 ± 17.5
• Post-training: 22.6 ± 14.6
• Paired t-test: p-value < 0.001
• Change in patterning primarily
correlated to  hamstring activation
• No change in quadriceps
• Hamstrings
• Pre: 22.18 ± 11.27
• Post: 17.56 ± 9.39
• r = 0.889
Representative Single Leg Land EMG Activity
50 ms pre-land to peak knee bending
Black: Pre-training; Green: Post-training
Knee Muscle Activation Patterning
Discussion
Standard cues tend to train selective recruitment of the
knee musculature, rather than bracing
Athletes are frequently warned away
from “quadriceps-dominance” but:
• Optimal landing is quadriceps
dominant behavior
• May abnormally increase joint
compression during high loading 6
Selective recruitment more
adaptive for high intensity tasks
References
1. Oiestad BL, Holm I, Aune AK, Gunderson R, Myklebust G, Engebretsen L, Fosdahl MA, Risberg MA. (2010).
Knee function and prevalence of knee osteoarthritis after anterior cruciate ligament reconstruction: A
prospective study with 10 to 15 years of follow-up. American Journal of Sports Medicine, 38(11): 2201-2210
2. Milner CE, Fairbrother JT, Srivatsan A, Zhang S. (2011). Simple verbal instruction improves knee
biomechanics during landing in female athletes. The Knee, 19(4):399-403
3. Hewett TE, DiStasi SL, Myer GD. (2012). Current concepts for injury prevention in athletes after anterior
cruciate ligament reconstruction. American Journal of Sports Medicine DOI: 10.1177/0363546512459638
4. Adams D, Logerstedt D, Hunter-Giordano A, Axe MJ, Snyder-Mackler L. (2012). Current concepts for anterior
cruciate ligament reconstruction: A criterion-based rehabilitation progression. Journal of Orthopaedic and
Sports Physical Therapy, 42(7):601-614
5. Rudolph KS, Axe MJ, Buchanan TS, Scholz JP, Snyder-Mackler L. (2001). Dynamic stability in the anterior
cruciate ligament deficient knee. Knee Surg, Sports Traumatol, Arthrosc. 9:62-71
6. Tsai L-C, McLean S, Colletti PM, Powers CM. (2012) Greater muscle co-contraction results in increased
tibiofemoral compressive forces in females who have undergone anterior cruciate ligament reconstruction.
Journal of Orthopaedic Research, 30:2007-2014