a heel drop-raise exercise Taija Finni Neuromuscular Research - PowerPoint PPT Presentation

Muscle-tendon mechanics of a heel drop-raise exercise Taija Finni Neuromuscular Research Center Department of Biology of Physical Activity University of Jyväskylä Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Stretch-Shortening Cycle Braking phase Push-off phase Muscle-tendon unit Lengthens Shortens ? ? Muscle fibers Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä Taija Finni 2001, PhD defense

When does eccentric muscle action occur? WALKING What was this RUNNING locomotion? Fascicle length change (mm) Cronin & Finni 2013 HOPPING Hoffren et al. 2012 Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Heel drop-raise exercise • Calf-raise test -> clinical test • Heel raise exercise Eccentric • Heel drop-raise exercise component? Alfredson et al. 1998 Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Muscle-tendon function in heel drop-raise exercise Taija Finni, Emma Niemi, Andrew G Cresswell & Glen A Lichtwark Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Muscle-tendon function in heel drop-raise exercise Taija Finni, Emma Niemi, Andrew G Cresswell & Glen A Lichtwark How is tendon and aponeurosis length (and stiffness) modulated with increasing force and in different types of muscle actions? Hypotheses: • With higher load the tendon elongates more but the aponeurosis does not. Force Tendon Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä Length

Tendon-aponeurosis strain% Aponeurosis of insertion Free Achilles tendon MVC Achilles tendon Aponeurosis Reference & % strain strain muscle 0 2 4 Arampatzis et al. 2006 GM - elongated 20 2.8 <1.2 Finni et al. 2003 SOL nonuniform 40 4.7 <2.2 Finni et al. 2003 SOL nonuniform 100 8.0 1.4 Magnusson et al. 2003 GM Force Relevance: Use of elastic potential in tendon, Tendon optimize muscle performance Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä Length

Tendon vs. aponeurosis Tibialis anterior muscle Aponeurosis length changes do At given TA force, length of elastic not depend on force alone but tissues dependes on muscle length: longer length, smaller length chang depend critically on activation Raiteri et al. 2016 ASBabstract level... Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä Tilp et al. 2012

Muscle-tendon function in heel drop-raise exercise Taija Finni, Emma Niemi, Andrew G Cresswell & Glen A Lichtwark How is tendon and aponeurosis length (and stiffness) modulated with increasing force and in different types of muscle actions? Hypotheses: • With higher load the tendon elongates more but the aponeurosis does not. • Aponeurosis stiffness is different between contraction modes at a given force level • Tilp et al 2012: TA aponeurosis lengthens less in eccentric vs. concentric action. Muscle fascicle function? Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Methods • Bilateral & Unilateral • 30 & 50 times/minute • With body weight up to +40%BW Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Movement symmetry Time of the phases Mean tendon forces of the phases 3.0 1,2 CON 2.5 CON mean Achilles tendon force (kN) 1 ECC ECC mean 2.0 0,8 Time (s) 1.5 0,6 1.0 0,4 0,2 0.5 0 0 BL BL+30 BL+40 UL UL+10 UL+30 30/min 50/min Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Methods MG fascicle Muscle- tendon junction • • Bilateral & Unilateral Motion capture • • 30 & 50 times/minute Ground reaction forces • • With body weight up to +40%BW Ultrasonography Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Heel raise-drop cycle Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Methods Ultrasound in lab space MG fascicle Aponeurosis MG tendon • Joint moments -> Achilles tendon force • Joint angles -> MG muscle-tendon unit length Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Achilles tendon force Moment arm ratios change Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

ATF (N) MTU MTU min max 1000 CON ECC 800 600 4.5 400 ATma EMG (cm) (%) 4.4 0.6 0.4 0.2 0 AT moment arm in walking (Rasske et al. 2016) Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Activation level Mean Achilles tendon force (N) Normalized EMG (%MVC) Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Vibration stimulates Achilles tendon force collagen synthesis Do fluctuations provide stimulus for tendon? Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Do muscle fascicles stretch? WALKING RUNNING Fascicle length change (mm) Cronin & Finni 2013 Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Do muscle fascicles stretch in heel drop exercise? Concentric Eccentric Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä

Take home messages • Stretch of muscle fibers is uncoupled from MTU – Muscle specificity – Movement specificity • Tendon – aponeurosis behavior is uncoupled • Tendon oscillates in eccentric phase of heel drop – > stimulus for collagen synthesis? Taija Finni 22.9.2016 Biomechanics symposium, Jyväskylä