Neuromuscular Electrical Stimulation

Transcription

1 Neuromuscular Electrical Stimulation Part I: myth versus reality Nicola A. MAFFIULETTI, PhD Sion Electrical Stimulation for Muscle Strengthening Yakov Kots, Russia 6-7 strength jump height circumference 1

2 ES increases strength Protocolo de Kots Autor Tipo de corriente Modalidad de entrenamiento Nº Sesiones Grupos Ganancia (fuerza) Kotz (1971) 25 modulada 5Hz 1 x (1-5 ) % Portmann (1978) 25 modulada 5Hz 1 x (1-5 ) 24 28,8 % Lysens (1981) 25 modulada 5 Hz 1 x (1-5 ) % Owens y Malone (1983) 25 modulada 5Hz 1 x (1-5 ) 1 Ns. Laughman et al. (1983) 25 modulada 5 Hz 1 x (1-5 ) % Carrier y Mann (1983) 25 modulada 5 Hz 1 x (1-5 ) % Selkowitz (1985) 22 modulada 5 Hz 1 x (1-1 ) % Stefanowska et al. (1985) 25 modulada 25 Hz 1 x (1-5 ) % Miller et al. (198) 25 modulada 88 Hz 5 x 5 x (5-3 ) 15 3 % Cometti (1987) 25 modulada 5Hz 1 x (1-5 ) 9 33 % Willoughby y Simpson (1998) 3 x 8-1 x 85% R:3 Curl Cuádriceps 3 x 8-1 x 85% R:3 Salto Vertical 6 semanas 4 1- Fz + Elec.: 79,54 % 2- Solo Fz: 54,16% 3- Solo Elec.: 45,61% 4- Control: 3,92% 1-25,18 % % 3-2,33 % 4-,74 % Thanks to: Miguel Cases de Orozco - Miguel Fernández del Olmo Otros Protocolos Autor Tipo de corriente Modalidad de entrenamient o Nº Sesiones Grupos Ganancia Moritani y de Vries (1979) Isométricas al 65 % de la MVIC (1rep x 2 día) x3 sem. x 8 semanas % miembro entrenado 24.7 % contralateral. Halbach y Strauss (198) 5 Hz 1 x (1-5 ) % Eriksson el al. (1981) 2 Hz 12 x (15-15 ) % Romero et al. (1982) 2 Hz 112 x (4-4 ) 1 21 % Davies et al. (1985) 6 Hz 8 x (1-2 ) 4-11 % Stefanowska et al. (1985) 25 Hz 1 x (1-5 ) % Farrance et al. (1987) 5 Hz 3 x (12-48 ) 3 9 % Cabric y Appel (1987) 5 y 2 Hz x (5-2 ) 21 5 y 59 % Cannon y Cafarelli (1987) 5 Hz 15 x (3-1 ) % Duchateau y Hainaut (1988) 1 Hz 1 x (1-5 ) 3 13 % Ratton et al. (1989) 1 Atletas x 1 cada grupo muscular 12 semanas 2 Mejora significativa Thanks to: Miguel Cases de Orozco - Miguel Fernández del Olmo - Adaptado de García Manso ES increases strength Physical education students 4 wks, 12 sessions Triceps surae muscle (3 contr. 5:15 s 7 Hz) 3 Dopo Post 3 Post Dopo Forza (N) 2 1 Prima Pre Forza (N) 2 1 Prima Pre Specificity! Lunghezza (%) Velocità (m/s) Martin et al. Eur J Appl Physiol

3 ES increases strength Post-intervention rehabilitation Lieber et al. J Orthop Res 1996 Articular pathology (knee) Morrissey Sports Med 1988 COPD patients Neder et al. Thorax 22 Elderly (~72 years-old) Caggiano et al. J Orthop Sports Phys Ther 1994 Athletes sportsmen Maffiuletti et al. Int J Sports Med 2 - Med Sci Sports Exerc 22 Delitto et al. Int J Sports Med 1989 Electrical stimulation does not require the participation of the subject and its use is funny... Typical settings and RPE 12 1 Borg scale (-1) ES VOL 3

4 Typical ES session (75 Hz max. int.) 6 Plantar flexor muscles Torque level (% MVC) 5 Strength PF -1% KE Strength -2% 1 Knee extensor muscles Number of contraction Muscular soreness Soreness (-2) ES 2 VOL D-1 D D+1 D+2 D+3 Moreau et al. J Sport Sci 1995 Muscle damage 25 2 CK activity (IU/l) 15 1 ES VOL 5 D-1 D D+1 D+2 D+3 Moreau et al. J Sport Sci

5 Oxygen consumption min warm-up VO2 (ml/min/kg) Electrical stimulation at 75 Hz 2 5 min rest 5 min rest Time (min) Heart rate 12 1 Frequenza cardiaca (bpm) Electrical stimulation at Time (min) ES versus VOL Hamada et al. J Appl Physiol 24 5

6 Lactate Hamada et al. J Appl Physiol 24 Typical ES training program +2 sessions/week 3-6 weeks Isometric vs. dynamic +2-3 contractions/session Relax vs. contraction Morrissey Sports Med 1988 (modified) ES training program A Intensity (ma) Vastus Lateralis Vastus Medialis I II III IV V VI VII VIII IX Training session 6

7 ES training program B Strength (kg) Strength (% MVC) Evoked strength % MVC 4 2 I II III IV V VI VII VIII IX Training session ES training program 1 Evoked strength (kg) y = 1.91x R 2 = Session I Session IX Intensity (ma) Electrical stimulation activates directly the muscle fibers... 7

8 Origin Electrical pulse at the skin level Action potential in the terminal branches of the axons Neuromuscular junction Sarcolemma Interaction contractile Hultman et al. Pflügers Arch 1983 VOL ES 8

9 Propagation Reflex FORCE Sensory feed-back ACTION POTENTIAL Axons branches Direct FORCE Collins et al. J Neurosci 21 Afferentefferent propagation Terminology Electrical stimulation ES Electromyostimulation EMS Neuromuscular ES NMES Functional ES FES Neurostimulation TENS The orderly recruitment of motor units is reversed during electrical stimulation... 9

10 MU recruitment Large-fast ES Intermediate Small-slow Contraction intensity Hennemann et al. J Neurophysiol 1965 MU recruitment 1. Axon diameter (largest recruited first) 2. Anatomical feature (largest axons superficial) 3. Cutaneous receptors (alter recruitment order) Enoka Sports Med 1988 MU recruitment Is it possible to affirm reversal? Reversal VOL _ 6% ES _ ~3% Feiereisen et al. Exp Brain Res

11 Electrical stimulation parameters are very important for effectiveness... Frequency (Hz) Intensity (ma) Electrodes size position Waveform Pulse duration (µs) Pulse Duration = optimal for the motor axons stimulated, i.e., 2-4 µs Rectangular shape (biphasic) Alteration of the MU recruitment order Fang & Mortimer IEEE Trans Biomed Eng 1991 Vanderthommen & Crielaard Rev Med Liege 21 Frequency I [strength training] Kotz protocols 25 Hz modulated at 5 Hz 1 Hz modulated at 5-1 Hz Moreno-Aranda & Seireg J Biomech 1981 Classical protocols 5-12 Hz, to optimize muscular tetanus and force Hainaut & Duchateau Sports Med 1992 Effects on force comparable (Bircan et al. Clin Rehab 22) 11

12 Frequency II [strength training & recovery] _ frequency = _ fatigue!!! DeVahl Electrotherapy in Rehab Hz Low frequency recovery High frequency strength training real benefit? Intensity Maximal since ma = muscular tension Max tension (4-6% MVC) to obtain force Kernell et al. J Neurophysiol % MVC sufficient!! Stefanovska & Vodovnik Scand J Rehab Med 1985 Duty cycle ON = stimulation, contraction time OFF = recovery time On:off ratio Duty cycle = on / total (%) 4:2-3 s (1-2%) force 15:5 s (23%) rehabilitation Lake Sports Med 1992 Fatigue!! 12

13 Electrodes Excitatory electrode positive Motor point (~NMJ) Negative electrode bigger Large electrodes Carbonized rubber = low impedance Lieber & Kelly Phys Ther 1991 Reflection Lieber & Kelly Phys Ther 1991 «The most important determinant of tension evoked by ES is not electrode size or stimulation current, or any other external controllable factor, but some intrinsic properties of the muscle, e.g., individual motor nerve branching» Electrical stimulation is more effective than voluntary training for muscle strengthening... 13

14 Healthy individuals Bax et al. Sports Med in revision Unhealthy individuals Bax et al. Sports Med in revision Healthy versus Unhealthy Healthy Unhealthy ES Voluntary ES Voluntary complementarity! e.g., MU recruitment 14

15 The CNS does not participate during contractions triggered by electrical stimulation... ES and the neuromuscular system Nervous system _ Supraspinal _ Spinal Muscle CNS activation during ES fmri _ significant activation : - Primary motor area - Primary sensory area - Cingulate gyrus - thalamus - Cerebellum Smith et al. Exp Brain Res 23 Han et al. Am J Phys Med Rehab 23 15

16 Fatigue after ES MVC -9% Activation -4.5% Contractile -6% ES and the neuromuscular system Nervous system _ Supraspinal _ Spinal Muscle Neural adaptations to ES training 1 st consideration training duration! Cross-education effect Hortobagyi et al. Motor Control 1999 Surface EMG Colson et al. Int J Sports Med 2 Activation level Maffiuletti et al. J Appl Physiol 22 Coactivation and reflex (delayed) Jubeau et al. Submitted 16

17 Neural adaptations 35 Controlateral Contralateral Cross-education Maximal voluntary contraction (Nm) 3 25 Trained 2 Training Weeks Neural adaptations.14 EMG activity POST Triceps surae RMS / M wave * * * 5 Nm PRE 5 ms 1 mv Angular velocity ( /s) Neural adaptations Muscle activation ** Before After 17

18 Neural adaptations,6,5 * ** * Hmax/Mmax ratio,4,3,2,1 PRE POST POST Detraining H reflex TG CG TG CG Soleus Gastrocnemii,25 ** #,2 ** Coactivation Coactivation,15,1,5 TG CG PRE POST POST Detraining Adaptations to ES training Neural _ Supraspinal _ Spinal Muscular Voluntary and ES resistance training Strength Neural Muscular Time (weeks) Sale Med Sci Sports Exerc

19 Electrical stimulation training increases muscle mass... Muscular changes (unhealthy) Prevention muscular atrophy > immobilization Maintenance protein synthesis Gibson et al. The Lancet 1988 Prevention MHC I > SCI patients Crameri et al. Eur J Appl Physiol 2 Hypertrophy > SCI patients Dudley et al. Eur J Appl Physiol 1999 CSA life quality > refract. hearth failure Quittan et al. Am J Phys Med Rehab 21 Muscular changes (healthy) Enzim. activity-fibers dimension-mitoc. properties Eriksson et al. Int J Sports Med 1981 Number-diameter myonuclei CSA (type II) Cabric et al. Int J Sports Med 1987 MHC-IIA IIX & I - No hypertrophy! Perez et al. Pflügers Arch 22 No changes in muscle contractile properties Our laboratory? 19

20 Single case PRE POST CSA (? m2) 5 25 CSA (? m2) 5 25 slow fibres 2A fast fibres slow fibres Significantly different from PRE 2A fast fibres Single case PRE POST MHC-2X MHC-2A MHC-1 PRE POST MHC% 2 MHC% 2 MHC-1 MHC-2A MHC-2X MHC-1 MHC-2A MHC-2X MHC-neo MHC isoforms MHC isoforms Significantly different from PRE Muscular changes (healthy) Longer training periods 8 weeks 32 sessions ES Quadriceps femoris N = 12 Ultrasound imaging Quadriceps muscle CSA (cm_) B WK4 WK8 ### CG Significant hypertrophy EG Gondin et al. submitted 2

21 Electrical stimulation enhances muscle recovery... Time (min) Recovery High Intensity Exercise Neuromuscular tests Recovery interventions: passive active EMS Neuromuscular tests Neuromuscular tests All-out running test IMVC torque (% at Post value) No significant difference! Post45-5 Post min run 12% MAV Slope 18% - 2 min rest passive active EMS Lattier et al. Int J Sports Med (in press) Electrical stimulation is effective for fat burning... Which one has used ES? 21

22 Effect of ES on body comp-physical appearance Porcari et al. J Strength Cond Res 22 8 weeks 3/week with «representative» machine BB, TB, Abd, Quad, Ham muscles (45 min) No changes in: - BW, FM, skinfolds, girths - Isom-isok strength - Physical appearance But perceived changes in muscle strength and tone > ES group Take-home messages ES is an effective modality to increase muscle strength ES does not by-pass the CNS! Parameters are important but Neuromuscular effects very similar to voluntary contractions Future directions Effect on functional activities Effect in special populations Physiological differences between ES and voluntary contractions Optimal parameters 22

23 Nicola A. Maffiuletti, PhD «Grazie» «Merci» «Danke» 23