Aging does not affect voluntary activation of the ankle dorsiflexors during isometric, concentric, and eccentric contractions

2005 ◽  
Vol 99 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Malgorzata Klass ◽  
Stéphane Baudry ◽  
Jacques Duchateau
Keyword(s):  
Electrical Stimulation ◽  
Compound Muscle Action Potential ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
M Wave ◽  
Mechanical Responses ◽  
Age Related ◽  
Angular Velocities ◽  
General Slowing ◽  
Ankle Dorsiflexors

This study examines the age-related deficit in force of the ankle dorsiflexors during isometric (Iso), concentric (Con), and eccentric (Ecc) contractions. More specifically, the contribution of neural and muscular mechanisms to the loss of voluntary force was investigated in men and women. The torque produced by the dorsiflexors and the surface electromyogram (EMG) from the tibialis anterior and the soleus were recorded during maximal Iso contractions and during Con and Ecc contractions performed at constant angular velocities (5–100°/s). Central activation was tested by the superimposed electrical stimulation method during maximal voluntary contraction and by computing the ratio between voluntary average EMG and compound muscle action potential (M wave) induced by electrical stimulation (average EMG/M wave). Contractile properties of the dorsiflexor muscles were investigated by recording the mechanical responses to single and paired maximal stimuli. The results showed that the age-related deficit in force (collapsed across genders and velocities) was greater for Iso (20.5%; P < 0.05) and Con (38.6%; P < 0.001) contractions compared with Ecc contractions (6.5%; P > 0.05). When the torque produced during Con and Ecc contractions was expressed relative to the maximal Iso torque, it was significantly reduced in Con contractions and increased in Ecc contractions with aging, with the latter effect being more pronounced for women. In both genders, voluntary activation was not significantly impaired in elderly adults and did not differ from young subjects. Similarly, coactivation was not changed with aging. In contrast, the mechanical responses to single and paired stimuli showed a general slowing of the muscle contractile kinetics with a slightly greater effect in women. It is concluded that the force deficit during Con and Iso contractions of the ankle dorsiflexors in advanced age cannot be explained by impaired voluntary activation or changes in coactivation. Instead, this age-related adaptation and the mechanisms that preserve force in Ecc contractions appeared to be located at the muscular level.

scholarly journals Influence of Voluntary Contraction Level, Test Stimulus Intensity and Normalization Procedures on the Evaluation of Short-Interval Intracortical Inhibition

2020 ◽  
Vol 10 (7) ◽  
pp. 433
Author(s):  
Cécilia Neige ◽  
Sidney Grosprêtre ◽  
Alain Martin ◽  
Florent Lebon
Keyword(s):  
Healthy Subjects ◽  
Compound Muscle Action Potential ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Intracortical Inhibition ◽  
Voluntary Contraction ◽  
Experimental Conditions ◽  
Specific Level ◽  
M Wave ◽  
Spinal Motoneurones

Short-interval intracortical inhibition (SICI) represents an inhibitory phenomenon acting at the cortical level. However, SICI estimation is based on the amplitude of a motor-evoked potential (MEP), which depends on the discharge of spinal motoneurones and the generation of compound muscle action potential (M-wave). In this study, we underpin the importance of taking into account the proportion of spinal motoneurones that are activated or not when investigating the SICI of the right flexor carpi radialis (normalization with maximal M-wave (Mmax) and MEPtest, respectively), in 15 healthy subjects. We probed SICI changes according to various MEPtest amplitudes that were modulated actively (four levels of muscle contraction: rest, 10%, 20% and 30% of maximal voluntary contraction (MVC)) and passively (two intensities of test transcranial magnetic stimulation (TMS): 120 and 130% of motor thresholds). When normalized to MEPtest, SICI remained unchanged by stimulation intensity and only decreased at 30% of MVC when compared with rest. However, when normalized to Mmax, we provided the first evidence of a strong individual relationship between SICI and MEPtest, which was ultimately independent from experimental conditions (muscle states and TMS intensities). Under similar experimental conditions, it is thus possible to predict SICI individually from a specific level of corticospinal excitability in healthy subjects.

scholarly journals Maximum Voluntary Activation in Nonfatigued and Fatigued Muscle of Young and Elderly Individuals

2001 ◽  
Vol 81 (5) ◽  
pp. 1102-1109 ◽  
Author(s):  
Scott K Stackhouse ◽  
Jennifer E Stevens ◽  
Samuel CK Lee ◽  
Karen M Pearce ◽  
Lynn Snyder-Mackler ◽  
...  
Keyword(s):  
Maximum Voluntary Contraction ◽  
Quadriceps Femoris ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Elderly Subjects ◽  
Central Activation ◽  
Quadriceps Femoris Muscle ◽  
Age Related ◽  
Young Subjects ◽  
Femoris Muscle

Abstract Background and Purpose. Researchers studying central activation of muscles in elderly subjects (≥65 years of age) have investigated activation in only the nonfatigued state. This study examined the ability of young and elderly people to activate their quadriceps femoris muscles voluntarily under both fatigued and nonfatigued conditions to determine the effect of central activation failure on age-related loss of force. Subjects and Methods. Twenty young subjects (11 men, 9 women; mean age=22.67 years, SD=4.14, range=18–32 years) and 17 elderly subjects (8 men, 9 women; mean age=71.5 years, SD=5.85, range=65–84 years) participated in this study. Subjects were seated on a dynamometer and stabilized. Central activation was quantified, based on the change in force produced by a 100-Hz, 12-pulse electrical train that was delivered during a 3- to 5-second isometric maximum voluntary contraction (MVC) of the quadriceps femoris muscle. Next, subjects performed 25 MVCs (a 5-second contraction with 2 seconds of rest) to fatigue the muscle. During the last MVC, central activation was measured again. Results. In the nonfatigued state, elderly subjects had lower central activation than younger subjects. In the fatigued state, this difference became larger. Discussion and Conclusion. Central activation of the quadriceps femoris muscle in elderly subjects was reduced in both the fatigued and nonfatigued states when compared with young subjects. Some part of age-related weakness, therefore, may be attributed to failure of central activation in both the fatigued and nonfatigued states.

scholarly journals Lifelong strength training mitigates the age-related decline in efferent drive

2016 ◽  
Vol 121 (2) ◽  
pp. 415-423 ◽  
Author(s):  
Runar Unhjem ◽  
Mona Nygård ◽  
Lene T. van den Hoven ◽  
Simranjit K. Sidhu ◽  
Jan Hoff ◽  
...  
Keyword(s):  
Strength Training ◽  
Plantar Flexion ◽  
H Reflex ◽  
Voluntary Activation ◽  
M Wave ◽  
Reflex Amplitude ◽  
Age Related ◽  
Musculus Soleus ◽  
V Wave ◽  
Voluntary Contractions

Recently, we documented age-related attenuation of efferent drive to contracting skeletal muscle. It remains elusive if this indication of reduced muscle strength is present with lifelong strength training. For this purpose, we examined evoked potentials in the calf muscles of 11 [71 ± 4 (SD) yr] strength-trained master athletes (MA) contrasted with 10 (71 ± 4 yr) sedentary (SO) and 11 (73 ± 6 yr) recreationally active (AO) old subjects, as well as 9 (22 ± 2 yr) young controls. As expected, MA had higher leg press maximal strength (MA, 185 ± 32 kg; AO, 128 ± 15 kg; SO, 106 ± 11 kg; young, 147 ± 22 kg, P < 0.01) and rate of force development (MA, 5,588 ± 2,488 N/s; AO, 2,156 ± 1,100 N/s; SO, 2,011 ± 825 N/s; young, 3,663 ± 1,140 N/s, P < 0.05) than the other groups. MA also exhibited higher musculus soleus normalized V waves during maximal voluntary contractions (MVC) [maximal V wave amplitude/maximal M wave during MVC (Vsup/Msup); 0.28 ± 0.15] than AO (0.13 ± 0.06, P < 0.01) and SO (0.11 ± 0.05, P < 0.01), yet lower than young (0.45 ± 0.12, P < 0.01). No differences were apparent between the old groups in H reflex recorded at rest or during MVC [maximal H reflex amplitude/maximal M wave during rest (Hmax/Mmax); maximal H reflex amplitude during MVC/maximal M wave during MVC (Hsup/Msup)], and all were lower ( P < 0.01) than young. MA (34.4 ± 2.1 ms) had shorter ( P < 0.05) H reflex latency compared with AO (36.4 ± 3.7 ms) and SO (37.3 ± 3.2 ms), but longer ( P < 0.01) than young (30.7 ± 2.0 ms). Using interpolated twitch analysis, MA (89 ± 7%) had plantar flexion voluntary activation similar to young (90 ± 6%), and this was higher ( P < 0.05), or tended to be higher ( P = 0.06–0.09), than SO (83 ± 10%) and AO (84 ± 5%). These observations suggest that lifelong strength training has a protective effect against age-related attenuation of efferent drive. In contrast, no beneficial effect seems to derive from habitual recreational activity, indicating that strength training may be particularly beneficial for counteracting age-related loss of neuromuscular function.

Age-related changes in responses to nerve stimulation and catecholamines in isolated monkey cerebral arteries

1991 ◽  
Vol 260 (5) ◽  
pp. H1443-H1448 ◽  
Author(s):  
N. Toda
Keyword(s):  
Electrical Stimulation ◽  
Cerebral Artery ◽  
Vascular Tone ◽  
Cerebral Arteries ◽  
Mechanical Responses ◽  
Prostaglandin F2 Alpha ◽  
Age Related ◽  
Basilar Arteries ◽  
Median Effective Concentration ◽  
Regulation Of Vascular Tone

Mechanical responses to transmural electrical stimulation, nicotine, norepinephrine, and isoproterenol were compared in cerebral artery strips obtained from Japanese monkeys of different ages (1 mo, 1 yr, 4–7 yr, and greater than 7 yr old). Transmural electrical stimulation produced a contraction in the baby and juvenile monkey arteries contracted with prostaglandin F2 alpha, whereas the older monkey arteries responded to the stimulation with a relaxation. The stimulation-induced contraction was abolished or reversed to a relaxation by phentolamine; the relaxation was not influenced by propranolol and atropine but was abolished by tetrodotoxin, as was the response of the mature monkey arteries. Contractions caused by norepinephrine were greater in baby cerebral arteries than in the older monkey arteries; however, the apparent median effective concentration values did not differ. Middle cerebral artery contractions were greater than those of basilar arteries. The norepinephrine-induced contraction was suppressed by prazosin but not influenced by yohimbine. Isoproterenol (up to 10(-6) M) produced a greater relaxation in the baby arteries than in the older monkey arteries. It is suggested that adrenergic nerves innervating immature monkey cerebral arteries contribute to the regulation of vascular tone predominantly over nonadrenergic, noncholinergic vasodilator nerves, whereas the vasodilator nerves play a major role in the mature monkey arteries. alpha 1-Adrenoceptor subtype appears to be mainly involved in the norepinephrine-induced contraction of baby monkey cerebral arteries, as it is in that of the adult monkey arteries.

Effects of fatigue duration and muscle type on voluntary and evoked contractile properties

1997 ◽  
Vol 82 (5) ◽  
pp. 1654-1661 ◽  
Author(s):  
D. G. Behm ◽  
D. M. M. St-Pierre
Keyword(s):  
Muscle Activation ◽  
Compound Muscle Action Potential ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Contractile Properties ◽  
Plantar Flexors ◽  
Muscle Type ◽  
M Wave ◽  
Time To Peak ◽  
Muscle Action Potential

Behm, D. G., and D. M. M. St-Pierre. Effects of fatigue duration and muscle type on voluntary and evoked contractile properties. J. Appl. Physiol. 82(5): 1654–1661, 1997.—The effects of fatigue duration and muscle type on voluntary and evoked contractile properties were investigated with an isometric, intermittent, submaximal fatigue protocol. Four groups performed contractions of the plantar flexors and quadriceps at various intensities to produce long (LDF; 19 min 30 s)- and short-duration fatigue (SDF; 4 min 17 s). The LDF group had a significantly greater decrease in muscle activation than did the SDF group (12 vs. 5.8%) during recovery, although there was no difference in the impairment of maximum voluntary contraction force beyond 30 s of recovery. The significant decrease in the compound muscle action potential of the LDF group (M-wave amplitude; 14.7%) contrasted with the M-wave potentiation of the SDF group (15.7%), suggesting changes in membrane excitation may affect LDF. The quadriceps group performing contractions at 50% MVC experienced a smaller decrease in agonist electromyograph activity than did other groups, indicating both muscle and fatigue duration specificity. Impairments in excitation-contraction coupling were indicated by changes in quadriceps peak twitch and time to peak twitch while decreases in PF M-wave amplitudes suggested a disruption of membrane potentials. Results suggest that fatigue mechanisms may be duration (activation, half relaxation time) or muscle specific (electromyograph, twitch torque) or a combination of both (M wave, time to peak twitch torque).

Velocity dependence of eccentric strength in young and old men: the need for speed!

2015 ◽  
Vol 40 (7) ◽  
pp. 703-710 ◽  
Author(s):  
Geoffrey A. Power ◽  
Demetri P. Makrakos ◽  
Daniel E. Stevens ◽  
Charles L. Rice ◽  
Anthony A. Vandervoort
Keyword(s):  
Large Range ◽  
Young Men ◽  
Older Men ◽  
Isometric Strength ◽  
Voluntary Activation ◽  
Velocity Dependence ◽  
Younger Adults ◽  
Age Related ◽  
Angular Velocities ◽  
Old Men

Older adults better maintain eccentric strength relative to isometric strength, as indicated by a higher ratio of eccentric:isometric torque as compared with younger adults. The effect of increasing angular velocities (>200°/s) on the age-related maintenance of eccentric strength has not been tested and thus it is unknown whether the eccentric:isometric ratio is velocity dependent in old age. The purpose of this study was to investigate eccentric strength of the ankle dorsiflexors over a large range of lengthening angular velocities in young and older men. Isometric neuromuscular properties were assessed on a HUMAC NORM dynamometer. Nine young (∼24 years) and 9 older (∼76 years) healthy men performed maximal voluntary eccentric contractions at angular velocities of 15–360°/s. Despite near full voluntary activation (>95%), the older men were ∼30% weaker than the young men for isometric strength (P < 0.05). Across all lengthening velocities, older men had a greater eccentric:isometric ratio than young men (P < 0.05). Additionally, there was a velocity dependence of strength in both young and older men: eccentric strength increased as velocity increased up to 120°/s (P < 0.05) and plateaued thereafter. In young and older men, eccentric strength at 15°/s was ∼20% and ∼40% greater than isometric strength (P < 0.05), while at 360°/s eccentric strength was ∼50% and ∼90% greater, respectively (P < 0.05). These findings indicate that with increasing angular velocity, both young and older men have considerable increases in the eccentric:isometric ratio of torque production.

Neuromuscular Fatigue After Repeated Jumping With Concomitant Electrical Stimulation

2017 ◽  
Vol 12 (10) ◽  
pp. 1335-1340 ◽  
Author(s):  
Daria Neyroud ◽  
Jimmy Samararatne ◽  
Bengt Kayser ◽  
Nicolas Place
Keyword(s):  
Electrical Stimulation ◽  
Training Stimulus ◽  
Neuromuscular Electrical Stimulation ◽  
Voluntary Contraction ◽  
Neuromuscular Fatigue ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Jump Height ◽  
Before And After ◽  
Squat Jumps

Purpose:To evaluate the etiology and extent of neuromuscular fatigue induced by 50 squat jumps performed with and without neuromuscular electrical stimulation (NMES) of the knee extensors.Methods:Nine healthy, recreationally active men (24 ± 2 y) took part in 2 experiments. These consisted of 50 squat jumps performed with stimulation (NMES) or without (CON). Maximal voluntary contraction (MVC) force, maximal voluntary activation level (VAL), and forces evoked by single and double (10 and 100 Hz) stimulations were recorded before and after the 50 jumps. NMES was delivered at the maximal tolerated intensity.Results:Despite average jump height being ∼16% lower in the NMES than in the CON session, a reduction over time in jump height was only found in the NMES condition (−6%). After the 50 jumps, MVC force was reduced to a greater extent in NMES than in CON (−25% ± 11% vs −11% ± 12%). Similarly, forces evoked by single stimulations, as well as by 10-Hz and 100-Hz paired stimulations, were reduced to a greater extent in NMES (−33% ± 12%, −42% ± 15%, and −25% ± 13%) than in CON (−21% ± 6%, −30% ± 9%, and −14% ± 11%). VAL was not significantly altered by either condition.Conclusion:Performing repeated squat jumps with concomitant NMES induced a greater fatigue than squat jumps performed alone and might potentially represent a stronger training stimulus.

Short-term immobilization has a minimal effect on the strength and fatigability of a human hand muscle

1995 ◽  
Vol 78 (3) ◽  
pp. 847-855 ◽  
Author(s):  
A. J. Fuglevand ◽  
M. Bilodeau ◽  
R. M. Enoka
Keyword(s):  
Wave Amplitude ◽  
Compound Muscle Action Potential ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Emg Activity ◽  
Human Hand ◽  
Contraction Time ◽  
Endurance Time ◽  
M Wave ◽  
First Dorsal Interosseus

The purpose of this study was to determine the association between reduced fatigability typically observed in disused muscle and an improved resistance to the impairment of neuromuscular propagation. Endurance time of an isometric contraction sustained at 35% of maximum voluntary contraction (MVC) force and the fatigue-induced change in the evoked compound muscle action potential (M wave) were measured in the first dorsal interosseus muscle of human subjects before, during, and after 3 (n = 9) or 5 wk (n = 2) of immobilization. The immobilization procedure caused a substantial decline in the chronic electromyographic (EMG) activity (to 4% of control value) of the first dorsal interosseus muscle. Endurance time was found to be significantly correlated to the maintenance of M-wave amplitude during the fatigue task. However, neither of these variables was significantly affected by immobilization. Also, immobilization had no significant effect on the prefatigue values of MVC force and EMG or twitch contraction time or on the postfatigue changes in MVC force and EMG, M wave duration, twitch amplitude, and contraction time. In the unfatigued muscle, immobilization did cause an increase in twitch force (153%) and a decrease in M-wave amplitude (67%). It appears, therefore, that a healthy first dorsal interosseus muscle is generally resistant to adaptation when its use has been reduced for 3–5 wk by immobilization.

Neuromuscular Fatigue After a Ski Skating Marathon

2003 ◽  
Vol 28 (3) ◽  
pp. 434-445 ◽  
Author(s):  
Guillaume Y. Millet ◽  
Vincent Martin ◽  
Nicola A. Maffiuletti ◽  
Alain Martin
Keyword(s):  
Mechanical Response ◽  
Compound Muscle Action Potential ◽  
Vastus Lateralis ◽  
Femoral Nerve ◽  
Voluntary Contraction ◽  
Neuromuscular Fatigue ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Vastus Lateralis Muscle ◽  
Central Activation

The aim of this study was to characterize neuromuscular fatigue in knee extensor muscles after a marathon skiing race (mean ± SD duration = 159.7 ± 17.9 min). During the 2 days preceding the event and immediately after, maximal percutaneous electrical stimulations (single twitch, 0.5-s tetanus at 20 and 80 Hz) were applied to the femoral nerve of 11 trained skiers. Superimposed twitches were also delivered during maximal voluntary contraction (MVC) to determine maximal voluntary activation (%VA). EMG was recorded from the vastus lateralis muscle. MVC decreased with fatigue from 171.7 ± 33.7 to 157.3 ± 35.2 Nm (-8.4%; p < 0.005) while %VA did not change significantly. The RMS measured during MVC and peak-to-peak amplitude of the compound muscle action potential (PPA) from the vastus lateralis decreased with fatigue by about 30% (p < 0.01), but RMS•PPA−1was similar before and after the ski marathon. Peak tetanus tension at 20 Hz and 80 Hz (P020 and P080, respectively) did not change significantly, but P020•P080−1 increased (p < 0.05) after the ski marathon. Data from electrically evoked single twitches showed greater peak mechanical response, faster rate of force development, and shorter contraction time in the fatigued state. From these results it can be concluded that a ski skating marathon (a) alters slightly but significantly maximal voluntary strength of the knee extensors without affecting central activation, and (b) induces both potentiation and fatigue. Key words: low- and high-frequency electrical stimulation, central activation, potentiation

Postactivation potentiation influences differently the nonlinear summation of contractions in young and elderly adults

2005 ◽  
Vol 98 (4) ◽  
pp. 1243-1250 ◽  
Author(s):  
Stéphane Baudry ◽  
Malgorzata Klass ◽  
Jacques Duchateau
Keyword(s):  
Tibialis Anterior Muscle ◽  
Single Pulse ◽  
Voluntary Contraction ◽  
Elderly Adults ◽  
Postactivation Potentiation ◽  
Pulse Trains ◽  
Mechanical Responses ◽  
Age Related ◽  
The Difference ◽  
Frequency Of Stimulation

The force enhancement of a twitch after a maximal conditioning muscle contraction [i.e., postactivation potentiation (PAP)] is reduced with aging, but its influence on the summation of force in response to repetitive stimulation at different frequencies is not known. The purpose of this work was to compare the electrically evoked mechanical responses of the tibialis anterior muscle between young and elderly adults after a 6-s maximal voluntary contraction (MVC). The results showed that, immediately after the conditioning MVC, twitch torque and its maximal rate of development and relaxation were significantly enhanced in both groups, but the magnitude of potentiation was greater in young (148.0 ± 14.2, 123.7 ± 16.5, and 185.4 ± 36.5%, respectively) compared with elderly adults (87.4 ± 15.2, 63.8 ± 9.9, and 62.9 ± 11.0%, respectively). This age-related difference in potentiation of the twitch disappeared completely 1 min after the conditioning MVC. The potentiation of torque and speed-related parameters in response to two- and three-pulse trains, delivered at a constant interval of 10 ms (100 Hz), was less than for a single pulse for both groups. In young adults, the magnitude of PAP on the successive individual mechanical contributions within a train of stimuli declined progressively such that the third contribution did not differ significantly from the same contribution before the conditioning MVC. In contrast, the second and third contributions did not potentiate ( P > 0.05) in elderly adults. Although these contributions did potentiate significantly at a lower frequency of stimulation (20 Hz) in the two groups, the difference in PAP between young and elderly adults still persisted. This overall attenuation of potentiation with aging, however, appears to have a moderate influence on the decrement of the muscular performance.

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