Transcript PPT
QUANTIFYING QUICKNESS OF MUSCLE RELAXATION Laura Funk Presenting research project at a Conference Introduction • Neuromuscular quickness • How quickly you can contract • Related to daily activities and falls • Rate of Force Development-Scaling Factor (RFD-SF) • How Neuromuscular quickness is measured • Slope of Peak force and it’s rate Specific Aims • Quantify the ability to relax muscles quickly • Create RFR-SF based off of RFD-SF • Slope of peak force and rate of relaxation • Compare quickness of force production to muscle relaxation Why this is important • Daily Use: • Relax quickly to contract antagonist muscle • Stopping Short or Dodging • Muscle Relaxation- correlated with disease severity • Ie. Parkinson's, MS, Stroke • According to a study by Corcos Background • How relaxation relates to neurological population • Relaxation is actively controlled • Neurological diseases affect firing of neuron • Tend to over grip • Find it hard to relax muscles Methods • Subjects: • 12 healthy, right handed individuals • aged 20-34 • Device: • Hand held grip force (GF) measuring device • simplified view of finger placement: Figure 1: Grip force measuring experimental device Methods • Task: • generate 90 rapid isometric GF pulses. • Pulses produced as quick as possible • submaximal amplitudes between 20 and 80% of MVC. Large Pulse 80% Medium Pulse 40% Small Pulse 20% Figure 2: Visual on the screen as they Pulsed Methods This is what the pulses will look like at the end of the test: Figure 3: Isometric grip force (GF) pulses performed between 20 and 80% of MVC Results • 3 pulses overlapped (Small, Medium, Large) • Showed in alignment • Demonstrates how neurons fire TTP TTR Figure 4: GF pulses performed at various submaximal levels. TTP: time to peak; TTR: time to relax Figure 4: GF pulses performed at various submaximal levels. Results Centers are all equal • Same Peak time despite force level • Happens in healthy populations, not neurological TTP TTR TTP: time to peak; TTR: time to relax Figure 4: GF pulses performed at various submaximal levels. Results Colored dotted lines represent slopes • Large pulse has a steeper slope • Slope indicates quickness • Large pulse must be quicker TTP TTR TTP: time to peak; TTR: time to relax Results Contraction development is faster than relaxation • Development slope= 5.6 vs Relaxation slope= 5.0 Figure 5: GF pulses performed at various submaximal levels Results • R2 is the correlation between pulses • R2 is 0-1, 1 most correlated • Data shows high R2 Figure 5: GF pulses performed at various submaximal levels Results • P-value measures the significant difference • P-Value above .05 for both • Not significantly different P-Value= .2154 P-Value= .8296 Figure 5: Indices of neuromuscular quickness Discussion and Conclusion • RFR-SF and R2 could be extracted • Using brief force production tasks. • Muscle Relaxation is quantifiable • RFR-SF was similar to RFD-SF • potential variable that quantifies neuromuscular quickness • P-value indicted not significantly different Discussion and Conclusion • High R2s for development and relaxation • Indicating CNS also controls relaxation • Opposes belief that relaxation is purely mechanical Clinical Use • Assess severity of neuromuscular diseases • Slow relaxation could be an indication • Inconstant time to relaxation • Practical to use • Portable and small • Affordable Clinical Use • Quantifiable measure of improvement • More objective that observational assessment • Before and after medication • Before and after therapy Future Studies • Compare results using different Muscle Groups • Compare Healthy to neurological populations • Add Friction as a factor Work Cited • Bellumori et al. 2011. Exp Brain Res • Suzuki et al. 2015. J Neurophysiol • Corcos et al. 1996. Annals of Neurology