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

Author(s):  
Felix Proessl ◽  
Maria C. Canino ◽  
Meaghan E. Beckner ◽  
William R. Conkright ◽  
Alice D. LaGoy ◽  
...  

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.

2017 ◽  
Vol 123 (2) ◽  
pp. 364-374 ◽  
Author(s):  
Hamidollah Hassanlouei ◽  
Christopher W. Sundberg ◽  
Ashleigh E. Smith ◽  
Andrew Kuplic ◽  
Sandra K. Hunter

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.


2019 ◽  
Vol 122 (1) ◽  
pp. 241-250 ◽  
Author(s):  
Vianney Rozand ◽  
Jonathon W. Senefeld ◽  
Christopher W. Sundberg ◽  
Ashleigh E. Smith ◽  
Sandra K. Hunter

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.


2019 ◽  
Vol 60 (7) ◽  
pp. 1364-1373 ◽  
Author(s):  
Chloe Rezola-Pardo ◽  
Ana Rodriguez-Larrad ◽  
Julen Gomez-Diaz ◽  
Garbiñe Lozano-Real ◽  
Itxaso Mugica-Errazquin ◽  
...  

Abstract Background and Objectives There is evidence that exercise interventions counteract the functional and cognitive decline experienced by long-term nursing home (LTNH) residents. To determine the most effective exercise intervention, we compared the effects of a multicomponent exercise intervention and a walking intervention on physical and cognitive performance, habitual physical activity, affective function, and quality of life among older adults living in LTNHs. Research Design and Methods This 3-month single-blind randomized controlled trial (NCT03996083) involved 81 participants at 9 LTNHs randomly assigned to a multicomponent (MG) or a walking (WG) group. The MG participated in a twice-a-week individualized and progressive program composed of strength and balance exercises for 3 months. The WG was also individualized and participants walked up to 20 min per day. The primary outcome was the score on the short physical performance battery (SPPB). Secondary outcomes included other physical performance tests, habitual physical activity, cognitive performance, affective function, and quality of life. Results Compared with the WG, the MG group showed greater improvements in physical performance, including the SPPB (p &lt; .05). No significant differences were observed in cognitive performance or habitual physical activity. Both groups showed improvements in anxiety and quality of life (p &lt; .05). Discussion and Implications Although both interventions were effective in maintaining or improving affective function, the MG conferred greater improvements in physical function. Therefore, multicomponent interventions would be preferable over walking-only interventions. Otherwise, individualized and progressive walking interventions should be implemented to face the rapid decline in functionality encountered in LTNHs.


2021 ◽  
Vol 15 ◽  
Author(s):  
Amiri Matsumoto ◽  
Nan Liang ◽  
Hajime Ueda ◽  
Keisuke Irie

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.


Nutrients ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2607
Author(s):  
Noé Labata-Lezaun ◽  
Luis Llurda-Almuzara ◽  
Carlos López-de-Celis ◽  
Jacobo Rodríguez-Sanz ◽  
Vanessa González-Rueda ◽  
...  

The aim of this study was to evaluate the effectiveness of the combination of resistance training (RT) and protein supplementation (PS), compared to RT alone or combined with a placebo (plS), in the improvement of muscle strength and physical performance. The search strategy in PubMed, Cochrane Library, and Web of Sciences databases found a total of 294 studies. Once inclusion and exclusion criteria were applied, 16 studies were included for the qualitative analysis. A total of 657 healthy elderly (>60 years) participants were analysed. Finally, 15 articles were included in the quantitative analysis with one being excluded due to issues with data availability. Upper-limb, lower-limb, and handgrip strength were the primary outcomes of the meta-analysis. The secondary outcomes, related to physical performance, were Short Physical Performance Battery (SPPB), gait speed, and the five-chair-rise test (5CRT). The main results of the meta-analysis show no statistical differences for upper-limb (SMD: 0.56, 95% CI: −0.09, 1.21, p = 0.09, I2 = 68%), lower-limb (SMD: 0.00, 95% CI: −0.18, 0.18, p = 1.0, I2 = 11%), and handgrip strength (SMD: 0.03, 95% CI: −0.26, 0.32, p = 0.84, I2 = 0%) between the RT + PS and the RT alone (or combined with plS). Moreover, no statistical differences were found relating to physical performance. In view of these results, protein supplementation combined with RT does not provide additional benefits compared to RT alone or with plS in healthy elderly adults.


VASA ◽  
2008 ◽  
Vol 37 (4) ◽  
pp. 327-332 ◽  
Author(s):  
Koutouzis ◽  
Sfyroeras ◽  
Moulakakis ◽  
Kontaras ◽  
Nikolaou ◽  
...  

Background: The aim of this study was to investigate the presence, etiology and clinical significance of elevated troponin I in patients with acute upper or lower limb ischemia. The high sensitivity and specificity of cardiac troponin for the diagnosis of myocardial cell damage suggested a significant role for troponin in the patients investigated for this condition. The initial enthusiasm for the diagnostic potential of troponin was limited by the discovery that elevated cardiac troponin levels are also observed in conditions other than acute myocardial infarction, even conditions without obvious cardiac involvement. Patients and Methods: 71 consecutive patients participated in this study. 31 (44%) of them were men and mean age was 75.4 ± 10.3 years (range 44–92 years). 60 (85%) patients had acute lower limb ischemia and the remaining (11; 15%) had acute upper limb ischemia. Serial creatine kinase (CK), isoenzyme MB (CK-MB) and troponin I measurements were performed in all patients. Results: 33 (46%) patients had elevated peak troponin I (> 0.2 ng/ml) levels, all from the lower limb ischemia group (33/60 vs. 0/11 from the acute upper limb ischemia group; p = 0.04). Patients with lower limb ischemia had higher peak troponin I values than patients with upper limb ischemia (0.97 ± 2.3 [range 0.01–12.1] ng/ml vs. 0.04 ± 0.04 [0.01–0.14] ng/ml respectively; p = 0.003), higher peak CK values (2504 ± 7409 [range 42–45 940] U/ml vs. 340 ± 775 [range 34–2403] U/ml, p = 0.002, respectively, in the two groups) and peak CK-MB values (59.4 ± 84.5 [range 12–480] U/ml vs. 21.2 ± 9.1 [range 12–39] U/ml, respectively, in the two groups; p = 0.04). Peak cardiac troponin I levels were correlated with peak CK and CK-MB values. Conclusions: Patients with lower limb ischemia often have elevated troponin I without a primary cardiac source; this was not observed in patients presenting with acute upper limb ischemia. It is very important for these critically ill patients to focus on the main problem of acute limb ischemia and to attempt to treat the patient rather than the troponin elevation per se. Cardiac troponin elevation should not prevent physicians from providing immediate treatment for limb ischaemia to these patients, espescially when signs, symptoms and electrocardiographic findings preclude acute cardiac involvement.


2019 ◽  
Vol 5 (3) ◽  
pp. 74
Author(s):  
Rezarta Stena ◽  
Klara Hysenaj ◽  
Mitilda Gugu Karoli ◽  
Armelda Teta ◽  
Gjergji Doka

It is known that worldwide populations are aging, and also that physical activity can play an important role in minimizing impairments characteristic of old age. Adopting a more active lifestyle and doing regular physical activity, including aerobic and resistance exercises, daily walking etc. have been demonstrated to improve cardiovascular, respiratory, and musculoskeletal parameters in older adults. We assessed a potential participant from Elbasan (Albania), 67 years, for eligibility to participate in a 5 month training program. The subject gave written informed consent before inclusion.The following parameters were measured at the beginning (baseline) and end of the training period: BMI, body fat percentage, hand grip strength, lower/upper limb and trunk flexibility and range of motion, heart rate, balance, pain intensity, as well as VO2 max, directly and/or an estimate using the Rockport fitness test estimate. An initial evaluation was carried out just before starting the training (baseline). A second evaluation was made 5 months after starting the program of physical exercise (post training). Each evaluation included the recording of health related events, such as any changes in previous symptoms, as well as measurements of balance, flexibility, body composition, coordination, muscle strength, and aerobic capacity, to detect any changes that might have been induced specifically by physical activity. The subject’s attendance and participation in the program was also recorded. Range of motion for each part evaluated (trunk, hip, cervical region and shoulder) is improved about 15-20° degree. BMI, hand grip strength, lower/upper limb and trunk flexibility, heart rate, balance, pain intensity, VO2 max are also improved after training program. Following a training program or a regular physical activity in older adults minimise impairments characteristics in this age and cardiovascular, respiratory, and musculoskeletal parameters. According to the low importance shown in my country for the physical activity in older adults, I want to emphasize the importance of state structures involvement and the sensibilization of this group of age to stimulate an actively participation in physical training programs followed by professionals for bests life parameters. A higher investment for this age group, building as many facilities as possible for activation and spending quality free time, hiring more physiotherapists in nursing homes will increase life motivation and improve the quality and the parameters of living.


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