Adam R. Jajtner1 , Gerald T. Mangine1, Tyler C. Scanlon1, Jeffery R. Stout, FACSM1, Jeremy R. Townsend1, William P. McCormack1, Adam M. Gonzalez1, Adam J. Wells1, Joseph P. Rogowski2, Edward H.
Robinson IV1 , Nadia S. Emerson1, Maren S. Fragala1, and Jay R. Hoffman, FACSM11
Institute of Exercise Physiology and Wellness, University of Central Florida, Orlando, Florida1; Orlando Magic Basketball Club, Orlando, Florida2
Lower-limb injury may cause deficits in muscle quality and muscle architecture,
ultimately leading to reduced sport performance.
Purpose: To determine the effect of lower-limb injury on measures of muscle quality
as assessed by echo intensity (EI); in addition to muscle architecture assessed by
muscle thickness (MT), pennation angle (PA) and cross sectional area (CSA).
Methods: Ten current NBA players (24.3 ± 3.8 years; 1.99 ± 0.08 m; 105.4 ± 15.1
kg) were assessed using bilateral ultrasound measures of the vastus lateralis to
determine EI, MT, PA, and CSA. All ultrasound measures were obtained at 50% of
the distance between the greater trochanter and the lateral epicondyle of the femur.
All images were analyzed utilizing Image J software. Independent t-tests and
magnitude based inferences were used to compare the bilateral differences of
healthy versus injured athletes. A 90% confidence level was assigned for all results.
Results: Data suggest lower-limb injury to have a “likely” or “most likely” negative
impact on the magnitude of difference between lower-limbs when measured by
absolute values or percent change for measures of muscle size (MT and CSA). All
other results remain “unclear” or “likely trivial” (EI and PA).
Conclusion: Results indicate a greater difference in muscle size (MT and CSA) for
the injured compared to healthy NBA players. Therefore, ultrasound measurement of
vastus lateralis muscle size may be beneficial for measuring bilateral discrepancies,
which may potentially be an additional assessment to predict an athletes’ readiness
to return to play post injury.
METHODS CON.
METHODS CON.
Ultrasound Measures
Statistical Analysis
• Subjects laid in a supine position for 15 minutes prior to sampling; all machine
settings were standardized (frequency: 12 MHz; gain: 50; dynamic range: 72; depth:
5 cm)
• Sampling position was located at 50% of the straight line distance between the
greater trochanter and the lateral epicondyle of the femur
• Once images were obtained, analysis was completed utilizing Image J software
(National Institutes of Healthy, USA, version 1.45s)
• Cross sectional area images were obtained in the transverse plane, and analyzed by
tracing the outside of the vastus lateralis using the free-hand tool in Image J
• Care was taken to ensure the fascia was not included as this would influence the
echo intensity; which was obtained from the same image (Figure 1)
• Echo intensity is a quantification of the grayscale within the specified area; values
range on an arbitrary scale from 0 to 256
• Muscle thickness was measured in the longitudinally, in the sagittal plane (Figure 2)
• Pennation angle was determined by connecting selecting a line to parallel the
fascicles of the muscle, and determining the angle of intersection with the fascia
(Figure 2)
• Differences between healthy and injured players were determined by magnitude
based inferences
• An independent t-test and magnitude based inferences were used to assess absolute
differences as well as percent changes between healthy and injured players
• A confidence interval was set at 90% for all t-tests (1)
• Magnitude based inferences were calculated via a published spread sheet (5)
RESULTS
Mean Effect
Interpretation
Muscle Thickness (cm)
0.06 ± 0.06
0.37 ± 0.19
-0.3 ± 0.3
Likely Negative
Pennation Angle (°)
2.53 ± 2.53
2.40 ± 0.70
0.1 ± 2.0
Unclear
Cross Section Area (cm )
0.77 ± 0.57
4.38 ± 1.71
-3.6 ± 3.0
Likely Negative
Echo Intensity
3.28 ± 2.30
3.87 ± 0.32
-0.6 ± 1.7
Likely Trivial
7
• Determine whether acute injure is capable of reducing echo intensity in otherwise
healthy NBA players
• Determine the influence of lower-limb injury on measures of muscle architecture
(pennation angle and echo intensity) and muscle size (cross sectional area and
muscle thickness) were also measured.
Healthy Players
Injured Players
6
*
^
#
4
3
^
2
*
1
Muscle Thickness
(cm)
Pennation Angle (°) Cross Section Area
(cm^2)
Figure 4: Bilateral discrepancies between healthy and injured players based on absolute differences
* - Indicates a “likely” difference
# - Indicates a “likely trivial” difference
^ - Indicates an “unclear” difference
NBA.com
Muscle Thickness
2.59 ± 2.62
21.76 ± 13.53
-19.2 ± 23.0
Likely Negative
Pennation Angle
20.15 ± 22.24
24.31 ± 10.07
-4.2 ± 26.0
Unclear
Cross Section Area
2.47 ± 1.89
14.33 ± 5.01
-11.9 ± 0.0
Most Likely Negative
Echo Intensity
6.01 ± 4.93
5.45 ± 0.21
0.6 ± 5.5
Unclear
40
Healthy Players
Injured Players
^
#
35
30
*
25
20
15
^
10
5
0
Muscle Thickness
Pennation Angle
Cross Section Area
Echo Intensity
Ultrasound Measure
Figure 6: Bilateral discrepancies between healthy and injured players based on percent differences
* - Indicates a “very likely” difference
# - Indicates a “likely” difference
^ - Indicates an “unclear” difference
• Results indicate a lower-limb injury is “very likely” or “likely” to impact muscle size in
NBA players
• Results also indicate a lower-limb injury is either “unclear” or “likely trivial” on
measures concerning muscle architecture (EI and PA) in NBA players
• Measures of muscle architecture are likely non-beneficial to determining and athletes
ability to return to competition following an injury in the lower-limbs
• Changes in echo intensity through inactivity may develop over long periods of time
(8), however, acute injury does not reduce echo intensity when compared with
healthy controls
• With the occurrence of decreased muscle size in NBA players following an injury,
ultrasonographic measures of muscle size (CSA and MT) may prove to be an
additional assessment to determine an athletes ability to return to play
• Further research is needed to determine if returning to competition with bilateral
discrepancies leads to an increased risk of re-injury
REFERENCES
Echo Intensity
Ultrasound Measure
Figure 2: Ultrasound image portraying analysis of muscle thickness and pennation angle.
Interpretation
SUMMARY & CONCLUSIONS
0
METHODS
• Ten members of the NBA franchise Orlando Magic (24.3 ± 3.8 0; 1.99 ± 0.08 m;
105.4 ± 15.1 kg) underwent ultrasound measurements on both dominant and
non-dominant legs
• Ultrasound measurements were completed on the athlete’s vastus lateralis, and
consisted of muscle thickness, pennation angle, cross sectional area and echo
intensity
• The health of the lower limbs of each individual player was provided to the
research team by the strength and conditioning staff of the Orlando Magic, as
assessed by the team physician
• These players were then separated into two groups based on lower limb injury,
healthy (n=7) and injured (n=3)
• To determine bilateral discrepancies, the absolute value of the difference between
legs was used
Injured (n=3)
5
Mean Effect
45
Absolute Differences
Bilateral Difference (Specified Units)
PURPOSE
Healthy (n=7)
Figure 3: Group averages (mean ± SD), mean effects and interpretations for each ultrasound measurement based
on absolute differences
Figure 1: Ultrasound image demonstrating the measurement used for cross sectional
area and echo intensity. Cross sectional area is represented by “area” while echo
intensity is represented by “mean”.
Injured (n=3)
Percent Differences
• It is “likely” that injured players have a greater bilateral discrepancy in the size of the
vastus lateralis (as assessed by both MT and CSA) when compared to starters
• It is “unclear” whether there is a difference in PA between players who are injured
and healthy
• The difference in EI between injured and healthy players is “likely trivial”
• Further information is provided in figures 3 and 4.
2
Healthy (n=7)
Figure 5: Group averages (mean ± SD), mean effects and interpretations for each ultrasound measurement based on percent
differences
Absolute Differences
INTRODUCTION
• Muscle atrophy in the lower limb is expected following immobilization, which is
common following injury when measured by magnetic resonance imaging (MRI) (6)
• Ultrasound measurements are valid and reliable when compared to MRI (7)
• Therefore, the use of ultrasound to assess changes in muscle size may prove
valuable to both amateur and professional athletes
• Echo intensity has been associated with:
• Skeletal muscle power in elderly men (3)
• Strength in elderly and middle-age individuals (4)
• Muscle quality in middle-aged and elderly individuals (3, 4)
• Echo intensity increases with aging (2), possibly due to a limited physical
activity (8)
RESULTS CONT.
Bilateral Difference (% Difference)
ABSTRACT
Percent Differences
• It is “likely” there is a greater bilateral discrepancy in athletes that are injured versus
athletes that are healthy in muscle thickness
• It is “most likely” the bilateral discrepancy for injured individuals is greater than the
bilateral discrepancy for healthy individuals in cross sectional area
• It is unclear whether the bilateral discrepancies for healthy and injured athletes differ
for measures of muscle architecture (pennation angle and echo intensity)
• Further information is provided in figures 5 and 6
1.
2.
3.
4.
5.
6.
7.
8.
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