scholarly journals Differential effects of aging and physical activity on corticospinal excitability of upper and lower limb muscles

2019 ◽  
Vol 122 (1) ◽  
pp. 241-250 ◽  
Author(s):  
Vianney Rozand ◽  
Jonathon W. Senefeld ◽  
Christopher W. Sundberg ◽  
Ashleigh E. Smith ◽  
Sandra K. Hunter
Keyword(s):  
Physical Activity ◽  
Lower Limb ◽  
Magnetic Stimulation ◽  
Corticospinal Tract ◽  
Vastus Lateralis ◽  
Corticospinal Excitability ◽  
Response Curves ◽  
Stimulus Response ◽  
Lower Limb Muscles ◽  
Limb Muscles

Corticospinal tract excitability can be altered by age, physical activity (PA), and possibly sex, but whether these effects differ between upper and lower limb muscles is unknown. We determined the influence of age, PA, and sex on corticospinal excitability of an upper limb and a lower limb muscle during submaximal contractions by comparing stimulus-response curves of motor evoked potentials (MEPs). Transcranial magnetic stimulation (TMS) was used to evoke stimulus-response curves in active muscles by incrementally increasing the stimulator intensity from below the active motor threshold (AMT) until a plateau in MEP amplitudes was achieved. Stimulus-response curves were analyzed from the first dorsal interosseous (FDI) of 30 young (23.9 ± 3.8 yr) and 33 older (72.6 ± 5.6 yr) men and women and the vastus lateralis (VL) of 13 young (23.2 ± 2.2 yr) and 25 older (72.7 ± 5.5 yr) men and women. Corticospinal excitability was determined by fitting the curves with a four-parameter sigmoidal curve and calculating the maximal slope (slopemax). PA was assessed with triaxial accelerometry, and participants were dichotomized into high-PA (>10,000 steps/day, n = 15) or low-PA (<10,000 steps/day, n = 43) groups. Young adults had larger FDI MEP amplitudes (% maximum amplitude of compound muscle action potential) at higher TMS intensities (120–150% AMT) and greater slopemax than older adults ( P < 0.05), with no differences between high- and low-PA groups ( P > 0.05). VL MEP amplitudes and slopemax, however, were lower in the high-PA than low-PA participants, with no age or sex differences. These data suggest that aging and PA, but not sex, differentially influence the excitability of the corticospinal tracts projecting to muscles of the upper compared with the lower limb. NEW & NOTEWORTHY Excitability of the corticospinal tract projecting to the first dorsal interosseous assessed with transcranial magnetic stimulation was reduced with age but independent of regular physical activity (steps/day) and sex of the individual. In contrast, corticospinal excitability of the vastus lateralis was not affected by age but was reduced in individuals achieving more than the physical activity recommendations of 10,000 steps/day. Aging and activity differentially affect corticospinal excitability of upper and lower limb muscles.

scholarly journals Physical activity modulates corticospinal excitability of the lower limb in young and old adults

2017 ◽  
Vol 123 (2) ◽  
pp. 364-374 ◽  
Author(s):  
Hamidollah Hassanlouei ◽  
Christopher W. Sundberg ◽  
Ashleigh E. Smith ◽  
Andrew Kuplic ◽  
Sandra K. Hunter
Keyword(s):  
Physical Activity ◽  
Nervous System ◽  
Lower Limb ◽  
Magnetic Stimulation ◽  
Corticospinal Tract ◽  
Corticospinal Excitability ◽  
Response Curves ◽  
Old Adults ◽  
Stimulus Response ◽  
Optimal Health

Aging is associated with reduced neuromuscular function, which may be due in part to altered corticospinal excitability. Regular physical activity (PA) may ameliorate these age-related declines, but the influence of PA on corticospinal excitability is unknown. The purpose of this study was to determine the influence of age, sex, and PA on corticospinal excitability by comparing the stimulus-response curves of motor evoked potentials (MEP) in 28 young (22.4 ± 2.2 yr; 14 women and 14 men) and 50 old adults (70.2 ± 6.1 yr; 22 women and 28 men) who varied in activity levels. Transcranial magnetic stimulation was used to elicit MEPs in the active vastus lateralis muscle (10% maximal voluntary contraction) with 5% increments in stimulator intensity until the maximum MEP amplitude. Stimulus-response curves of MEP amplitudes were fit with a four-parameter sigmoidal curve and the maximal slope calculated (slopemax). Habitual PA was assessed with tri-axial accelerometry and participants categorized into either those meeting the recommended PA guidelines for optimal health benefits (>10,000 steps/day, high-PA; n = 21) or those not meeting the guidelines (<10,000 steps/day, low-PA; n = 41). The MEP amplitudes and slopemax were greater in the low-PA compared with the high-PA group ( P < 0.05). Neither age nor sex influenced the stimulus-response curve parameters ( P > 0.05), suggesting that habitual PA influenced the excitability of the corticospinal tract projecting to the lower limb similarly in both young and old adults. These findings provide evidence that achieving the recommended PA guidelines for optimal health may mediate its effects on the nervous system by decreasing corticospinal excitability. NEW & NOTEWORTHY Transcranial magnetic stimulation was used to determine whether achieving the recommended 10,000 steps/day for optimal health influenced the excitability of the corticospinal tract projecting to the knee extensor muscles. Irrespective of age and sex, individuals who achieved >10,000 steps/day had lower corticospinal excitability than those who performed <10,000 steps/day, possibly representing greater control of inhibitory and excitatory networks. Physical activity involving >10,000 steps/day may mediate its effects on the nervous system by decreasing corticospinal excitability.

Use-dependent corticospinal excitability is associated with resilience and physical performance during simulated military operational stress

2021 ◽  
Author(s):  
Felix Proessl ◽  
Maria C. Canino ◽  
Meaghan E. Beckner ◽  
William R. Conkright ◽  
Alice D. LaGoy ◽  
...  
Keyword(s):  
Physical Activity ◽  
Cognitive Performance ◽  
Physical Performance ◽  
Upper Limb ◽  
Lower Limb ◽  
Corticospinal Excitability ◽  
Response Curves ◽  
Operational Stress ◽  
Stimulus Response ◽  
Psychophysiological Stress

Simulated military operational stress (SMOS) provides a useful model to better understand resilience in humans as the stress associated with caloric restriction, sleep deficits, and fatiguing exertion degrades physical and cognitive performance. Habitual physical activity may confer resilience against these stressors by promoting favorable use-dependent neuroplasticity, but it is unclear how physical activity, resilience, and corticospinal excitability (CSE) relate during SMOS. PURPOSE: To examine associations between corticospinal excitability, physical activity, and physical performance during SMOS. METHODS: Fifty-three service members (age: 26±5yrs, 13 women) completed a five day and night intervention composed of familiarization, baseline, SMOS (two nights/days), and recovery days. During SMOS, participants performed rigorous physical and cognitive activities while receiving half of normal sleep (two 2h blocks) and caloric requirements. Lower and upper limb CSE were determined with transcranial magnetic stimulation (TMS) stimulus-response curves. Self-reported resilience, physical activity, military-specific physical performance (TMT) and endocrine factors were compared in individuals with high (HIGH) and low CSE based on a median split of lower limb CSE at baseline. RESULTS: HIGH had greater physical activity and better TMT performance throughout SMOS. Both groups maintained physical performance despite substantial psychophysiological stress. Physical activity, resilience, and TMT performance were directly associated with lower limb CSE. CONCLUSION: Individual differences in physical activity coincide with lower (but not upper) limb CSE. Such use-dependent corticospinal excitability directly relates to resilience and physical performance during SMOS. Future studies may use non-invasive neuromodulation to clarify the interplay among CSE, physical activity, and resilience and improve physical and cognitive performance.

Reproducible Measurement of Human Motoneuron Excitability With Magnetic Stimulation of the Corticospinal Tract

2009 ◽  
Vol 102 (1) ◽  
pp. 606-613 ◽  
Author(s):  
Peter G. Martin ◽  
Anna L. Hudson ◽  
Simon C. Gandevia ◽  
Janet L. Taylor
Keyword(s):  
Magnetic Stimulation ◽  
Corticospinal Tract ◽  
Motor Evoked Potentials ◽  
Compound Action Potential ◽  
Maximal Response ◽  
Response Curves ◽  
Stimulus Response ◽  
Maximal Output ◽  
Voluntary Contractions ◽  
Stimulation Of

It is difficult to test responses of human motoneurons in a controlled way or to make longitudinal assessments of adaptive changes at the motoneuron level. These studies assessed the reliability of responses produced by magnetic stimulation of the corticospinal tract. Cervicomedullary motor evoked potentials (CMEPs) were recorded in the first dorsal interosseus (FDI) on 2 separate days. On each day, four sets of stimuli were delivered at the maximal output of the stimulator, with the final two sets ≥10 min after the initial sets. Sets of stimuli were also delivered at different stimulus intensities to obtain stimulus-response curves. In addition, on the second day, responses at different stimulus intensities were evoked during weak voluntary contractions. Responses were normalized to the maximal muscle compound action potential ( Mmax). CMEPs evoked in the relaxed FDI were small, even when stimulus intensity was maximal (3.6 ± 2.5% Mmax) but much larger during a weak contraction (e.g., 26.2 ± 10.2% Mmax). CMEPs evoked in the relaxed muscle at the maximal output of the stimulator were highly reproducible both within (ICC = 0.83, session 1; ICC = 0.87, session 2) and between sessions (ICC = 0.87). ICCs for parameters of the input-output curves, which included measures of motor threshold, slope, and maximal response size, ranged between 0.87 and 0.62. These results suggest that responses to magnetic stimulation of the corticospinal tract can be assessed in relaxation and contraction and can be reliably obtained for longitudinal studies of motoneuronal excitability.

scholarly journals Timing and Modulation of Activity in the Lower Limb Muscles During Indoor Rowing: What Are the Key Muscles to Target in FES-Rowing Protocols?

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1666
Author(s):  
Taian M. Vieira ◽  
Giacinto Luigi Cerone ◽  
Costanza Stocchi ◽  
Morgana Lalli ◽  
Brian Andrews ◽  
...  
Keyword(s):  
Lower Limb ◽  
Tibialis Anterior ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Sample Surface ◽  
Recovery Phase ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Stimulation Of

The transcutaneous stimulation of lower limb muscles during indoor rowing (FES Rowing) has led to a new sport and recreation and significantly increased health benefits in paraplegia. Stimulation is often delivered to quadriceps and hamstrings; this muscle selection seems based on intuition and not biomechanics and is likely suboptimal. Here, we sample surface EMGs from 20 elite rowers to assess which, when, and how muscles are activated during indoor rowing. From EMG amplitude we specifically quantified the onset of activation and silencing, the duration of activity and how similarly soleus, gastrocnemius medialis, tibialis anterior, rectus femoris, vastus lateralis and medialis, semitendinosus, and biceps femoris muscles were activated between limbs. Current results revealed that the eight muscles tested were recruited during rowing, at different instants and for different durations. Rectus and biceps femoris were respectively active for the longest and briefest periods. Tibialis anterior was the only muscle recruited within the recovery phase. No side differences in the timing of muscle activity were observed. Regression analysis further revealed similar, bilateral modulation of activity. The relevance of these results in determining which muscles to target during FES Rowing is discussed. Here, we suggest a new strategy based on the stimulation of vasti and soleus during drive and of tibialis anterior during recovery.

scholarly journals Corticospinal Excitability of the Lower Limb Muscles During the Anticipatory Postural Adjustments: A TMS Study During Dart Throwing

2021 ◽  
Vol 15 ◽  
Author(s):  
Amiri Matsumoto ◽  
Nan Liang ◽  
Hajime Ueda ◽  
Keisuke Irie
Keyword(s):  
Upper Limb ◽  
Lower Limb ◽  
Primary Motor Cortex ◽  
Anticipatory Postural Adjustments ◽  
Limb Movement ◽  
Corticospinal Excitability ◽  
Postural Adjustments ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Dart Throwing

Objective: To investigate whether the changes in the corticospinal excitability contribute to the anticipatory postural adjustments (APAs) in the lower limb muscles when performing the ballistic upper limb movement of the dart throwing.Methods: We examined the primary motor cortex (M1) excitability of the lower limb muscles [tibialis anterior (TA) and soleus (SOL) muscles] during the APA phase by using transcranial magnetic stimulation (TMS) in the healthy volunteers. The surface electromyography (EMG) of anterior deltoid, triceps brachii, biceps brachii, TA, and SOL muscles was recorded and the motor evoked potential (MEP) to TMS was recorded in the TA muscle along with the SOL muscle. TMS at the hotspot of the TA muscle was applied at the timings immediately prior to the TA onset. The kinematic parameters including the three-dimensional motion analysis and center of pressure (COP) during the dart throwing were also assessed.Results: The changes in COP and EMG of the TA muscle occurred preceding the dart throwing, which involved a slight elbow flexion followed by an extension. The correlation analysis revealed that the onset of the TA muscle was related to the COP change and the elbow joint flexion. The MEP amplitude in the TA muscle, but not that in the SOL muscle, significantly increased immediately prior to the EMG burst (100, 50, and 0 ms prior to the TA onset).Conclusion: Our findings demonstrate that the corticospinal excitability of the TA muscle increases prior to the ballistic upper limb movement of the dart throwing, suggesting that the corticospinal pathway contributes to the APA in the lower limb in a muscle-specific manner.

scholarly journals Effect of Foot Orthoses on the Timing of Lower Limb Muscles Activity during Walking in Older Adults

2021 ◽  
Author(s):  
Arefeh Mokhtari MalekAbadi ◽  
Amirali Jafarnezhadgero
Keyword(s):  
Older Adults ◽  
Lower Limb ◽  
Vastus Lateralis ◽  
Gluteus Medius ◽  
Erector Spinae ◽  
Medial Gastrocnemius ◽  
Female Group ◽  
Vastus Medialis ◽  
Lower Limb Muscles ◽  
Limb Muscles

Introduction: As a person gets older, their gait patterns change and their ability to walk decreases. Orthoses are used to relieve musculoskeletal disorders, skeletal problems, disabilities, etc. Therefore, the aim of this study was to investigate the effect of orthoses on timing of lower limb muscles in the older adults during gait. Methods: The present study was a clinical trial. 14 females (with average age of 60.50±4.40 years) and 14 males (with average age of 63.35±5.55 years) were selected with available sampling, voluntarily participated in this research. Eight electrodes were placed on the selected muscles (tibialis anterior, gastrocnemius medial, vastus medialis, vastus lateralis, biceps femoris, semitendinosus, gluteus medius, erector spinae) to record electrical activity during the gait with and without orthoses. To analyze the data SPSS software (version 16), and a repeated analysis of variance test was used. The significance levels in all tests were considered to be 0.05. Results: The main effects of orthoses and the interaction effects of orthoses and sex for the onset of selected muscles activities did not show any significant differences (P>0.05). The effect of sex for the onset of activities in medial gastrocnemius (P=0.007), vastus medialis (P=0.002), vastus lateralis (P=0.027), semitendinosus (P=0.004), gluteus medius (P=0.030), and erector spinae (P=0.039) muscles was significant, so that the onset of muscle activity in the female group was earlier than in the male group. Conclusion: Orthoses showed no improvement on onset of selected muscles activities, although significant differences were observed between the male and female groups.

scholarly journals Using transcranial magnetic stimulation to map the cortical representation of lower-limb muscles

2019 ◽  
Author(s):  
Jennifer L Davies
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Lower Limb ◽  
Magnetic Stimulation ◽  
Motor Evoked Potentials ◽  
The Body ◽  
Double Cone ◽  
Cortical Representation ◽  
Lower Limb Muscles ◽  
Main Effect ◽  
Limb Muscles

AbstractThe aim of this study was to evaluate the extent to which transcranial magnetic stimulation (TMS) can identify discrete cortical representation of lower-limb muscles in healthy individuals. Data were obtained from 16 young healthy adults (12 women, four men; mean [SD] age 23.0 [2.6] years). Motor evoked potentials were recorded from the resting vastus medialis, rectus femoris, vastus lateralis, medial and lateral hamstring, and medial and lateral gastrocnemius muscles on the right side of the body using bipolar surface electrodes. TMS was delivered through a 110-mm double-cone coil at 63 sites over the left hemisphere. Location and size of the cortical representation and the number of discrete peaks were quantified for each muscle. Within the quadriceps muscle group there was a main effect of muscle on anterior-posterior centre of gravity (p = 0.010), but the magnitude of the difference was very small. Within the quadriceps there was a main effect of muscle on medial-lateral hotspot (p = 0.027) and map volume (p = 0.047), but no post-hoc tests were significant. The topography of each lower-limb muscle was complex, displaying multiple peaks that were present across the stimulation grid, and variable across individuals. The results of this study indicate that TMS delivered with a 110-mm double-cone coil could not reliably identify discrete cortical representations of resting lower-limb muscles when responses were measured using bipolar surface electromyography. The characteristics of the cortical representation of lower-limb muscles reported here provide a basis against which to evaluate cortical reorganisation in clinical populations.

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