ABSTRACT

1. MUSCULAR POWER CORRELATES TO ECHO INTENSITY AND MUSCLE ARCHITECTURE IN NCAA DIVISION I FEMALE SOCCER PLAYERS Tyler C. Scanlon, William P. McCormack, Jonathan D. Bohner, Adam J. Wells, Adam R. Jajtner, Jeremy R. Townsend, Nadia S. Emerson, Adam M. Gonzalez, Edward H. Robinson IV, Gabriel J. Pruna, Carleigh H. Boone, MarenS. Fragala, Jay R. Hoffman FACSM, Jeffery R. Stout FACSM Human Performance Laboratory, University of Central Florida, Orlando, FL., USA, Figure 2. Correlation between peak power (W) and vastus lateralis cross-sectional area (cm^2). ABSTRACT METHODS • Measures • Muscle Thickness: For measures of MT, the probe was oriented parallel to the muscle tissue interface. Thickness was measured as the perpendicular distance from the superficial aponeurosis to the deep aponeurosis. • Cross-sectional area: For measures of CSA, the probe was oriented perpendicular to the muscle tissue interface. Scans were conducted using LV (logiq view) mode ultrasonography. The polygon tool was used in ImageJ (National Institutes of Health, USA, version 1.45s). to outline as much of the muscle as possible without including any surrounding fascia. • Echo intensity: Echo intensity values were obtained using the same images as for CSA. EI was determined by grayscale analysis (figure 1) using the standard histogram function in ImageJ, where an increased value denotes a lower quality, stemming from a higher acoustical impedance due to an increase in intramuscular adipose and connective tissue. • Peak Vertical Jump Power: Participants were instructed to place hands on hips while jumping. Body mass was entered in kilograms to calculate power in wattage. 5 jumps were performed non-consecutively. The highest recorded wattage was accepted as peak jump power. BACKGROUND: High muscular power output is desirable for sport success and is determined by many collective architectural properties of muscle. Muscle ultrasonography is often used to non-invasively evaluate muscle architecture through measures of muscle thickness (MT) and muscle cross-sectional area (CSA). In addition, recent technological advances in ultrasound measures has provided an ability to assess muscle quality through echo intensity (EI), in which fibrous tissue and intramuscular adipose is measured relative to contractile units. To our knowledge no data exists examining the relationship between power output, muscle architecture and muscle quality in female college athletes. PURPOSE: To examine the relationship between lower extremity peak jump power (JP) and measures of muscle architecture and muscle quality in competitive female soccer players. METHODS: Peak vertical jump power was assessed intwenty-six division-1 female soccer players (age: 19.4 ± 1.1; height: 169.3 ± 7.7 cm; weight: 64 ± 6.9 kg). MT, CSA, and EI of the rectus femoris (RF) and vastus lateralis (VL) were evaluated with ultrasonography. Relative muscle quality (MQ) and relative thigh muscle quality (tMQ) were calculated as (EI/CSA) and (RF+VL EI/ RF+VL CSA), respectively. Pearson’s correlation coefficients were computed to assess the relationship among variables. RESULTS:Peak vertical jump power demonstrated significant correlations with vastus lateralis cross-sectional area (VL-CSA), vastus lateralis relative muscle quality (VL-MQ), as well as tMQ. CONCLUSIONS: Peak jump power was significantly correlated to vastus lateralis CSA, vastus lateralis relative MQ, and thigh relative MQ in female soccer athletes. Results suggest that power output is related not only to muscle CSA, but also muscle quality per unit of muscle mass as assessed by ultrasonography. Study Protocol r=.62* Figure 3. Correlation between peak power (W) and vastus lateralis muscle quality (EI/cm^2). *p ≤ .05 r= -.54* Figure 4. Correlation between peak power (W) and thigh muscle quality (EI/cm^2). • Figure 1. Echo intensity of the rectus femoris quantified using grayscale analysis. • Participants rested supine for 15 minutes allowing for any fluid shifts to occur. • MT, CSA, and EI of the rectus femoris (RF) and vastus lateralis (VL) were evaluated with ultrasonography. • A 12MHz linear probe scanning head (General Electric LOGIQ P5, Wauwatosa, WI, USA) with a gain of 50 dB, dynamic range of 72, and depth of 5 cm was used to optimize spatial resolution. The probe was coated with water soluble transmission gel and positioned on the surface of the skin to provide acoustic contact without depressing the dermal layer to collect the image. • For each measure, three consecutive images were captured analyzed (Koppenhaver et al. 2009). The same investigator performed all ultrasound measurements. (ICC) for MT was 0.89 (SEM= .12), for CSA ICC was 0.99 (SEM= 1.26), and for EI, ICC was 0.93 (SEM= 5.1). • For images of RF: Participant placed supine, with legs extended but relaxed and toes pointed toward the ceiling. A rolled towel was placed beneath the popliteal fossa to allow for a 10 degree bend in the knee as measured by goniometer (Bemben 2002). Measurements were taken at 50% of limb length, determined as half the distance from the anterior, inferior iliac to the proximal border of the patella. • For images of VL: Participant placed recumbent on non-dominant leg side with legs bent at 10 degrees. Toes angled approximately 45 degrees in relation to the frontal plane. Measurements were taken at 50% of limb length, determined as the midpoint from the most prominent point of the greater trochanter of the femur to the lateral epicondyle (Thomaes et al. 2012). r= -.47* *p ≤ .05 INTRODUCTION • High muscular power output is desirable for sport success and is determined by many collective architectural properties of muscle. • Muscle ultrasonography is often used to non-invasively evaluate muscle architecture through measures of muscle thickness (MT) and muscle cross-sectional area (CSA). • Recent technological advances in ultrasound measures have provided an ability to assess muscle quality through echo intensity (EI), in which fibrous tissue and intramuscular adipose is measured relative to contractile tissue. • To our knowledge no data exist examining the relationship between power output, muscle architecture and muscle quality in female college athletes. (EI/cm^2) *p ≤ .05 RESULTS SUMMARY & CONCLUSIONS • Peak jump power was significantly correlated to vastus lateralis CSA, vastus lateralis relative MQ, and thigh relative MQ in female soccer athletes. • Peak vertical jump power demonstrated significant correlations with vastus lateralis cross-sectional area (VL-CSA; figure 2), vastus lateralis relative muscle quality (VL-MQ; figure 3), as well as tMQ (figure 4). • The table and figures below present the correlation of jump power to measures of muscle quality and quantity. • Results suggest that power output is related not only to muscle CSA, but also muscle quality per unit of muscle mass as assessed by ultrasonography. • Further research is warranted to investigate the relationship between muscle quality and various performance measures including, but not limited to muscular power in collegiate female athletes. • Peak vertical jump power assessment using an accelerometer. • Relative muscle quality (MQ) and relative thigh muscle quality (tMQ) were calculated as (EI/CSA) and [(RF EI + VL EI) / (RF CSA + VL CSA)], respectively. • Peak vertical jump power was assessed via accelerometer fixed with a pelvic strap and with hands on waist. Table 1.Correlation of jump power to measures of muscle quality and quantity. PURPOSE Analysis output given as a mean pixel count ranging 0-255 Au. • Pearson’s correlation coefficients were computed to assess the relationship among variables. REFERENCES • To examine the relationship between lower extremity peak jump power (JP) and measures of muscle architecture and muscle quality in competitive female soccer players. Bemben, M.G. Use of Diagnostic Ultrasound for Assessing Muscle Size. Journal of Strength and Conditioning Research. 16 (1): 103-108, 2002. Koppenhaver, S.L., Parent, E.C., Teyhen, D.S., Hebert, J.J., Fritz, J.M. The effect of averaging multiple trials on measurement error during ultrasound imaging of transverse abdominis and lumbar multifidus muscles in individuals with lower back pain. Journal of Orthopedic and Sports Physical Therapy. 39 (8): 604-611, 2009. Thomaes, T., Thomis, M., Onkelinx, S., Coudyzer, W., Cornelissen, V., and Vanhees, L. Reliability and validity of the ultrasound technique to measure the rectus femoris muscle diameter in older CAD-patients. BMC Medical Imaging. 12 (7): 2012. Vastus lateralis Rectus femoris Cross-sectional sweep of the vastus lateralis in LV mode. Hamstrings Vastus intermedius • Collection of muscle architecture and muscle quality images. Femur