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Baranauskiene N, Wang J, Eimantas N, Solianik R, Brazaitis M. Age-related differences in the neuromuscular performance of fatigue-provoking exercise under severe whole-body hyperthermia conditions. Scand J Med Sci Sports 2023; 33:1621-1637. [PMID: 37218443 DOI: 10.1111/sms.14403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 05/08/2023] [Accepted: 05/12/2023] [Indexed: 05/24/2023]
Abstract
PURPOSE The purpose of this study was to determine if aging would lead to greater decline in neuromuscular function during a fatiguing task under severe whole-body hyperthermia conditions. METHODS Twelve young (aged 19-21 years) and 11 older (aged 65-80 years) males were enrolled in the study, which comprised a randomized control trial under a thermoneutral condition at an ambient temperature of 23°C (CON) and an experimental trial with passive lower body heating in 43°C water (HWI-43°C). Changes in neuromuscular function and fatigability, and physical performance-influencing factors such as psychological, thermoregulatory, neuroendocrine, and immune responses to whole-body hyperthermia were measured. RESULTS A slower increase in rectal temperature, and a lower heart rate, thermal sensation, and sweating rate were observed in older males than young males in response to HWI-43°C trial (p < 0.05). Nevertheless, prolactin increased more in response to hyperthermia in young males, while interleukin-6 and cortisol levels increased more in older males (p < 0.05). Peripheral dopamine levels decreased in older males and increased in young males in response to hyperthermia (p < 0.05). Surprisingly, older males demonstrated greater neuromuscular fatigability resistance and faster maximal voluntary contraction (MVC) torque recovery after a 2-min sustained isometric MVC task under thermoneutral and severe hyperthermic conditions (p < 0.05). CONCLUSION Neuromuscular performance during fatigue-provoking sustained isometric exercise under severe whole-body hyperthermia conditions appears to decline in both age groups, but a lower relative decline in torque production for older males may relate to lower psychological and thermophysiological strain along with a diminished dopamine response and prolactin release.
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Affiliation(s)
- Neringa Baranauskiene
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Junli Wang
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Nerijus Eimantas
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Rima Solianik
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Marius Brazaitis
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
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Eimantas N, Ivanove S, Baranauskiene N, Solianik R, Brazaitis M. Modulation of neuromuscular excitability in response to acute noxious heat exposure has no additional effects on central and peripheral fatigability. Front Physiol 2022; 13:936885. [PMID: 36035478 PMCID: PMC9412021 DOI: 10.3389/fphys.2022.936885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 07/19/2022] [Indexed: 11/15/2022] Open
Abstract
Background: Whole-body hyperthermia (WBH) has an adverse effect on the nervous system and neurophysiological performance. In the present study, we examined whether short-duration whole-body immersion in 45°C water (HWI-45°C), which produces a strong neural and temperature flux without inducing WBH, can increase or impair neurophysiological performance in humans. Methods: Fifteen men (aged 25 ± 6 years) were enrolled in this study and participated in three experiments: 1) a brief (5-min) immersion of the whole body in 37°C water (WI-37°C); 2) a brief (5-min) HWI-45°C; and 3) a control trial in a thermoneutral condition at an ambient temperature of 24°C and 60% relative humidity. Before and after the immersions, neuromuscular function (electromyographic activity, reflexes, electrically and voluntary induced torque production, voluntary muscle activation level) were tested. To provoke central inhibition, the participants performed a sustained 2-min maximal voluntary contraction (MVC). Results: Thermophysiological strain was greater after HWI-45°C than after WI-37°C. Electrophysiological modulations of motor drive transmission and peripheral modulations of muscle contractility properties in response to HWI-45°C seemed to have little effect on central activation of the exercising muscles and no effect on MVC production. Conclusion: Although exposure to acute noxious heat was effective in evoking neuromuscular excitability, the increases in core temperature (∼0.2°C) and muscle temperature (∼0.6°C) did not induce moderate or severe WBH. These changes did not seem to affect central structures; that is, there were no additional increases in central and/or peripheral fatigue during a sustained 2-min MVC.
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Reliability of Tibialis Anterior Muscle Voluntary Activation Using the Interpolated Twitch Technique and the Central Activation Ratio in People with Stroke. Brain Sci 2021; 11:brainsci11020176. [PMID: 33535411 PMCID: PMC7912757 DOI: 10.3390/brainsci11020176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 01/24/2021] [Accepted: 01/26/2021] [Indexed: 12/04/2022] Open
Abstract
Voluntary activation (VA) is measured by applying supramaximal electrical stimulation to a muscle during a maximal voluntary contraction (MVC). The amplitude of the evoked muscle twitch is used to determine any VA deficit, and indicates incomplete central neural drive to the motor units. People with stroke experience VA deficits and greater levels of central fatigue, which is the decrease in VA that occurs following exercise. This study investigated the between-session reliability of VA and central fatigue of the tibialis anterior muscle (TA) in people with chronic stroke (n = 12), using the interpolated twitch technique (ITT), adjusted-ITT, and central activation ratio (CAR) methods. On two separate sessions, supramaximal electrical stimulation was applied to the TA when it was at rest and maximally activated, at the start and end of a 30-s isometric dorsiflexor MVC. The most reliable measures of VA were obtained using the CAR calculation on transformed data, which produced an ICC of 0.92, and a lower bound confidence interval in the good range (95% CI 0.77 to 0.98). Reliability was lower for the CAR calculation on non-transformed data (ICC 0.82, 95% CI 0.63 to 0.91) and the ITT and adjusted-ITT calculations on transformed data (ICCs 0.82, 95% CIs 0.51 to 0.94), which had lower bound confidence intervals in the moderate range. The two ITT calculations on non-transformed data demonstrated the poorest reliability (ICCs 0.62, 95% CI 0.25 to 0.74). Central fatigue measures demonstrated very poor reliability. Thus, the reliability for VA in people with chronic stroke ranged from good to poor, depending on the calculation method and statistical analysis method, whereas the reliability for central fatigue was very poor.
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Vadopalas K, Ratkevičius A, Skurvydas A, Sipavičienė S, Brazaitis M. Pre-Exercise Rehydration Attenuates Central Fatigability during 2-Min Maximum Voluntary Contraction in Hyperthermia. ACTA ACUST UNITED AC 2019; 55:medicina55030066. [PMID: 30871128 PMCID: PMC6473333 DOI: 10.3390/medicina55030066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 02/11/2019] [Accepted: 03/06/2019] [Indexed: 02/07/2023]
Abstract
Background and objectives: Hyperthermia with dehydration alters several brain structure volumes, mainly by changing plasma osmolality, thus strongly affecting neural functions (cognitive and motor). Here, we aimed to examine whether the prevention of significant dehydration caused by passively induced whole-body hyperthermia attenuates peripheral and/or central fatigability during a sustained 2-min isometric maximal voluntary contraction (MVC). Materials and Methods: Ten healthy and physically active adult men (21 ± 1 years of age) performed an isometric MVC of the knee extensors for 2 min (2-min MVC) under control (CON) conditions, after passive lower-body heating that induced severe whole-body hyperthermia (HT, Tre > 39 °C) with dehydration (HT-D) and after HT with rehydration (HT-RH). Results: In the HT-D trial, the subjects lost 0.94 ± 0.15 kg (1.33% ± 0.13%) of their body weight; in the HT-RH trial, their body weight increased by 0.1 ± 0.42 kg (0.1% ± 0.58%). After lower-body heating, the HT-RH trial (vs. HT-D trial) was accompanied by a significantly lower physiological stress index (6.77 ± 0.98 vs. 7.40 ± 1.46, respectively), heart rate (47.8 ± 9.8 vs. 60.8 ± 13.2 b min−1, respectively), and systolic blood pressure (−12.52 ± 5.1 vs. +2.3 ± 6.4, respectively). During 2-min MVC, hyperthermia (HT-D; HT-RH) resulted in greater central fatigability compared with the CON trial. The voluntary activation of exercising muscles was less depressed in the HT-RH trial compared with the HT-D trial. Over the exercise period, electrically (involuntary) induced torque decreased less in the HT-D trial than in the CON and HT-RH trials. Conclusions: Our results suggest that pre-exercise rehydration might have the immediate positive effect of reducing physiological thermal strain, thus attenuating central fatigability even when exercise is performed during severe (Tre > 39 °C) HT, induced by passive warming of the lower body.
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Affiliation(s)
- Kazys Vadopalas
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, LT-44221 Kaunas, Lithuania.
| | - Aivaras Ratkevičius
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, LT-44221 Kaunas, Lithuania.
| | - Albertas Skurvydas
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, LT-44221 Kaunas, Lithuania.
| | - Saulė Sipavičienė
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, LT-44221 Kaunas, Lithuania.
| | - Marius Brazaitis
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, LT-44221 Kaunas, Lithuania.
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Brazaitis M, Paulauskas H, Eimantas N, Daniuseviciute L, Volungevicius G, Skurvydas A. Motor performance is preserved in healthy aged adults following severe whole-body hyperthermia. Int J Hyperthermia 2018; 36:65-74. [PMID: 30484343 DOI: 10.1080/02656736.2018.1533650] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Healthy aging is associated with a progressive decline in motor performance and thermoregulatory efficiency. Functional consequences of severe whole-body hyperthermia on neurophysiological functions in healthy aged men have not been investigated. To determine whether severe whole-body hyperthermia (increase in rectal temperature of about 2.5 °C) induced by lower-body heating in older men (64-80 years, n = 9) would suppress excitability of reflexes, voluntarily and electrically induced ankle plantar flexor contractile properties were compared with those in young men (19-21 years, n = 11). Though no aging effect on hyperthermia-induced reflex amplitudes was observed, a decrease in maximal H-reflex and V-wave latencies was found to be greater in older than in young men. In older men, lower-body heating was accompanied by a significant increase in twitch and tetani test torque in parallel with a greater decrease in muscle contraction time. There was no temperature-depended aging effect on the voluntary activation and maximal voluntary torque production. Despite delayed and weakened thermoregulation and age-related decline in neuromuscular function, motor performance in whole-body severe hyperthermia is apparently preserved in healthy aging.
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Affiliation(s)
- Marius Brazaitis
- a Institute of Sport Science and Innovations , Lithuanian Sports University , Kaunas , LT , Lithuania
| | - Henrikas Paulauskas
- a Institute of Sport Science and Innovations , Lithuanian Sports University , Kaunas , LT , Lithuania
| | - Nerijus Eimantas
- a Institute of Sport Science and Innovations , Lithuanian Sports University , Kaunas , LT , Lithuania
| | - Laura Daniuseviciute
- b Department of Educational Studies , Kaunas University of Technology , Kaunas , LT , Lithuania
| | - Gintautas Volungevicius
- a Institute of Sport Science and Innovations , Lithuanian Sports University , Kaunas , LT , Lithuania
| | - Albertas Skurvydas
- a Institute of Sport Science and Innovations , Lithuanian Sports University , Kaunas , LT , Lithuania
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The Effect of Three Different Strategies Based on Motor Task Performance on Neuromuscular Fatigue in Healthy Men and Men with Multiple Sclerosis. ACTA ACUST UNITED AC 2018; 54:medicina54030033. [PMID: 30344264 PMCID: PMC6122107 DOI: 10.3390/medicina54030033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 05/01/2018] [Accepted: 05/11/2018] [Indexed: 11/16/2022]
Abstract
Background and objectives: Fatigue during physical activity occurs because of decreased neuromuscular function. The aim of this study was to evaluate the effect of three different strategies based on motor task performance on neuromuscular fatigue in healthy men and men with multiple sclerosis (MS). Materials and Methods: We studied age-matched (18⁻43 years of age) healthy men (n = 15) and men with MS (n = 9). The inclusion criteria for MS subjects were a Kurtzke Expanded Disability Status Score <4 and a Fatigue Severity Scale Score >5. Both groups performed one of three exercise trials (with at least a 1-week interval between them) of 100 intermittent isometric knee extensions with flexion of 60°. The three different experimental conditions (ECs) were intermittent isometric contraction tasks with constant, predictable, and unpredictable torque target sequences. The variation of maximal voluntary contraction contractions (MVCs) within the strategies was 25%, 50%, and 75%, with a set average of 50%. All of them had a 5 s contraction and a 20 s rest period. The variables were measured: before exercise, after 100 repetitions (100-Reps), and 1 h after exercise. Results: In all EC tasks, the central activation ratio values of healthy and MS subjects were significantly different; however, no significant differences were observed among the EC tasks. No significant differences were seen in electrically induced torque, MVC torque, muscle temperature, subjective sensation of effort, coefficient of variation, or constant and absolute error after 100-Reps and 1 h after exercise between the two groups and in all EC tasks. Conclusions: Men with MS experienced higher central motor fatigue than did healthy men, but this had no effect on the variability, accuracy, or force sensation of the movements performed.
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Kyguoliene L, Skurvydas A, Eimantas N, Baranauskiene N, Steponaviciute R, Daniuseviciute L, Paulauskas H, Cernych M, Brazaitis M. Three different motor task strategies to assess neuromuscular adjustments during fatiguing muscle contractions in young and older men. Exp Brain Res 2018; 236:2085-2096. [PMID: 29754195 DOI: 10.1007/s00221-018-5285-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 05/07/2018] [Indexed: 10/16/2022]
Abstract
Healthy aging is associated with a marked decline in motor performance. The functional consequences of applying varying novel or unexpected motor stimuli during intermittent isometric prolonged (fatiguing) motor tasks for lower limb neuromuscular fatigability and steadiness, perception of effort, and blood markers of stress in healthy aged men compared with young men have not been investigated. The participants in this study were 15 young men (aged 22 ± 4 years) and 10 older men (aged 67 ± 6 years). They performed 100 intermittent isometric knee extensions under three experimental conditions involving intermittent isometric contraction tasks according to constant, predictable, and unpredictable torque target sequences. The variability in maximal voluntary contraction averaged 50%, and was 25, 50, and 75% for the three strategies. All included a 5-s contraction and 20-s rest. The main variables were measured before exercise, after 100 repetitions, and 1 h after exercise. In all experimental trials, the decreases in the maximal voluntary contraction and central activation ratio, and the increases in effort sensation and muscle temperature, were smaller in older men than in younger men. The coefficient of variation during the motor performance did not differ between age groups. However, in all three strategies, the dopamine concentration was significantly higher in older than in younger men. The prolactin concentration did not differ significantly between age groups or conditions, although its decrease during loading correlated negatively with the central activation ratio.
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Affiliation(s)
- Laura Kyguoliene
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania
| | - Albertas Skurvydas
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania.,Institute of Sports Science and Innovation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania
| | - Nerijus Eimantas
- Institute of Sports Science and Innovation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania
| | - Neringa Baranauskiene
- Institute of Sports Science and Innovation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania
| | - Rasa Steponaviciute
- Department of Laboratory Medicines, Medical Academy, Lithuanian University of Health Science, Kaunas, Lithuania
| | - Laura Daniuseviciute
- Department of Physical Education, Kaunas University of Technology, Kaunas, Lithuania
| | - Henrikas Paulauskas
- Institute of Sports Science and Innovation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania
| | - Margarita Cernych
- Institute of Sports Science and Innovation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania
| | - Marius Brazaitis
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania. .,Institute of Sports Science and Innovation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania.
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Merlet AN, Cattagni T, Cornu C, Jubeau M. Effect of knee angle on neuromuscular assessment of plantar flexor muscles: A reliability study. PLoS One 2018; 13:e0195220. [PMID: 29596480 PMCID: PMC5875874 DOI: 10.1371/journal.pone.0195220] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 02/25/2018] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION This study aimed to determine the intra- and inter-session reliability of neuromuscular assessment of plantar flexor (PF) muscles at three knee angles. METHODS Twelve young adults were tested for three knee angles (90°, 30° and 0°) and at three time points separated by 1 hour (intra-session) and 7 days (inter-session). Electrical (H reflex, M wave) and mechanical (evoked and maximal voluntary torque, activation level) parameters were measured on the PF muscles. Intraclass correlation coefficients (ICC) and coefficients of variation were calculated to determine intra- and inter-session reliability. RESULTS The mechanical measurements presented excellent (ICC>0.75) intra- and inter-session reliabilities regardless of the knee angle considered. The reliability of electrical measurements was better for the 90° knee angle compared to the 0° and 30° angles. CONCLUSIONS Changes in the knee angle may influence the reliability of neuromuscular assessments, which indicates the importance of considering the knee angle to collect consistent outcomes on the PF muscles.
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Affiliation(s)
- Angèle N. Merlet
- Laboratory Movement, Interactions, Performance, Faculty of Sport Sciences, University of Nantes, Nantes, France
| | - Thomas Cattagni
- Laboratory Movement, Interactions, Performance, Faculty of Sport Sciences, University of Nantes, Nantes, France
- Inserm Unit 1179, Team 3: Technologies and Innovative Therapies Applied to Neuromuscular diseases, UVSQ. CIC 805, Physiology-Functional Testing Ward, AP-HP, Raymond Poincaré Teaching Hospital, Garches, France
- * E-mail:
| | - Christophe Cornu
- Laboratory Movement, Interactions, Performance, Faculty of Sport Sciences, University of Nantes, Nantes, France
| | - Marc Jubeau
- Laboratory Movement, Interactions, Performance, Faculty of Sport Sciences, University of Nantes, Nantes, France
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Sex-specific reliability and multidimensional stability of responses to tests assessing neuromuscular function. HOMO-JOURNAL OF COMPARATIVE HUMAN BIOLOGY 2017; 68:452-464. [PMID: 29175061 DOI: 10.1016/j.jchb.2017.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Accepted: 10/30/2017] [Indexed: 11/22/2022]
Abstract
The objective of this study was to estimate sex-specific effects in the test-retest cross-reliability of peripheral and central changes in nonlinear and linear measures of a surface electromyography signal during a brief (5 second) and sustained (2minute) isometric maximal voluntary contraction, combined with superimposed electrical stimulation involving the ankle plantar flexors over five identical trials. In this study, we repeated the testing protocol used in our previous study of 10 women (age 20.9, SD=0.3 years) (Bernecke et al., 2015) in a group of 10 men (age 21.2, SD=0.4 years). Despite the central (sex effect; p<0.05, ηp2>0.71, SP>70%) and peripheral fatigability (sex effect; p<0.01, ηp2>0.8, SP>90%) during sustained isometric maximal voluntary contraction, and lower reliability for central activation ratio during brief (intraclass correlation coefficient [ICC]=0.95 for men and ICC=0.82 for women) and sustained maximal voluntary contraction (ICC>0.82 for men and ICC>0.66 for women) over ankle plantar flexors expressed in women more than in men, all the ICCs of all indices measured by tests assessing neuromuscular function across the five identical test-retest trials were found as meaningful (correlation significance of p<0.05 was reached) and no significant differences were found between trials for any of the measured variables. In conclusion, the present study demonstrated greater central and peripheral fatigue for female participants following sustained (2minute) isometric maximal voluntary contraction of the plantar flexor muscles for all repeated trials and indicated an acceptable agreement between measurements of the characteristic variables made using the three different devices (dynamometry, electrical stimulation, and surface electromyography) over time for both sexes.
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Effect of constant, predictable, and unpredictable motor tasks on motor performance and blood markers of stress. Exp Brain Res 2017; 235:1323-1336. [PMID: 28204862 DOI: 10.1007/s00221-017-4894-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 01/24/2017] [Indexed: 12/25/2022]
Abstract
An unfamiliar or novel physical stimulus induces activation of dopaminergic neurons within the brain and greater activity in areas involved in emotion; considering this, we aimed to establish whether unpredictable prolonged (fatiguing) motor task (vs. constant vs. predictable) evokes greater dopaminergic activity, enhances neuromuscular performance, motor accuracy, and perception of effort, and delays overall central fatigue. Fifteen healthy male volunteers (aged 22 ± 4 years) were required to perform 1 of 3 exercise trials (at least 1 week apart) of 100 intermittent isometric contraction (IIC) tasks involving knee extensions at 60° flexion. Trials were structured differently by simulated contraction intensity. A fatigue task involved 5-s contractions and 20-s rest. Variables measured before, during, and after IIC were electrically induced force, maximal voluntary contraction, central activation ratio, intramuscular temperature, and blood levels of dopamine, cortisol, and prolactin, and intraindividual motor variability and accuracy (constant and absolute error). We found that IIC increased central and peripheral fatigue, force sensation, and T mu, and decreased absolute and constant error without visual feedback, but did not affect motor variability. There were no significant differences between the three IIC tasks. However, only unpredictable tasks increased dopaminergic activity, which was insufficient to affect central motivation to perform isometric exercise and alter centrally mediated components of fatigue.
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Brazaitis M, Paulauskas H, Skurvydas A, Budde H, Daniuseviciute L, Eimantas N. Brief Rewarming Blunts Hypothermia-Induced Alterations in Sensation, Motor Drive and Cognition. Front Physiol 2016; 7:592. [PMID: 27990123 PMCID: PMC5133047 DOI: 10.3389/fphys.2016.00592] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/15/2016] [Indexed: 12/25/2022] Open
Abstract
Background: It is well known that cold exposure experienced during occupational or recreational activities may adversely affect motor, cognitive performance, and health. Most research has used prolonged passive external rewarming modalities and focused on the direct effects on the kinetics of physiological and psychological responses in hypothermic subjects. However, the brief whole body rewarming effects on physiological and psychological responses in parallel with functional consequences on cognitive and neurophysiological functions have not been investigated. This study explores these effects in 12 healthy young men. Methods: Subjects (20 ± 1 years) participated in 4 randomized trials, which were designed to compare the effects of whole-body brief (5-min) rewarming in 37°C water with rewarming for the same duration in 24°C (air) thermoneutral environment in mildly hypothermic subjects. After each rewarming, indicators of neuromuscular function (reflexes, central activation ratio, electromyography of exercising muscle, and contractile properties of calf muscles) and cognitive function (attention, simple motor speed, and information processing speed) were assessed. Results: Compared to rewarming in thermoneutral environment, after brief rewarming in 37°C water, significantly lower metabolic heat production (MHP) (206 ± 33.4 vs. 121.9 ± 24.3 W·m2, P < 0.01), heart rate (76 ± 16 vs. 60 ± 12 b·min−1, P < 0.01), cold strain (6.4 ± 3.1 vs. 5.3 ± 2.7, P < 0.01), improved thermal comfort and induced cessation of shivering were found. Electrically induced maximum torque amplitudes increased (P100, 102.8 ± 21.3 vs. 109.2 ± 17.5 Nm and PTT100, 83.1 ± 17.1 vs. 92.7 ± 16.0 Nm, P < 0.05), contraction half-relaxation time decreased (599.0 ± 53.8 vs. 589.0 ± 56.3 ms, P < 0.05), and Mmax-wave latency shortened (17.5 ± 2.2 vs. 15.6 ± 2.0 ms, P < 0.05) after 37°C water rewarming. Unlike rewarming in thermoneutral environment, 37°C water rewarming blunted the hypothermia-induced alterations in neural drive transmission (4.3 ± 0.5 vs. 3.4 ± 0.8 mV H-reflex and 4.9 ± 0.2 vs. 4.4 ± 0.4 mV V-wave, P < 0.05), which increased central fatigue during a 2-min maximum load (P < 0.05). Furthermore, only in brief warm water rewarming cerebral alterations were restored to the control level and it was indicated by shortened reaction times (P < 0.05). Conclusions: Brief rewarming in warm water rather than the same duration rewarming in thermoneutral environment blunted the hypothermia-induced alterations for sensation, motor drive, and cognition, despite the fact that rectal and deep muscle temperature remained lowered.
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Affiliation(s)
- Marius Brazaitis
- Institute of Sport Science and Innovations, Lithuanian Sports University Kaunas, Lithuania
| | - Henrikas Paulauskas
- Institute of Sport Science and Innovations, Lithuanian Sports University Kaunas, Lithuania
| | - Albertas Skurvydas
- Institute of Sport Science and Innovations, Lithuanian Sports University Kaunas, Lithuania
| | - Henning Budde
- Institute of Sport Science and Innovations, Lithuanian Sports UniversityKaunas, Lithuania; Faculty of Human Sciences, Medical School HamburgHamburg, Germany; Sports Science Department, Reykjavik UniversityReykjavik, Iceland
| | - Laura Daniuseviciute
- Faculty of Social Sciences, Arts and Humanities, Kaunas University of Technology Kaunas, Lithuania
| | - Nerijus Eimantas
- Institute of Sport Science and Innovations, Lithuanian Sports University Kaunas, Lithuania
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Abboud J, Nougarou F, Loranger M, Descarreaux M. Test-retest reliability of trunk motor variability measured by large-array surface electromyography. J Manipulative Physiol Ther 2015. [PMID: 26209582 DOI: 10.1016/j.jmpt.2015.06.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE The objective of this study was to evaluate the test-retest reliability of the trunk muscle activity distribution in asymptomatic participants during muscle fatigue using large-array surface electromyography (EMG). METHODS Trunk muscle activity distribution was evaluated twice, with 3 to 4 days between them, in 27 asymptomatic volunteers using large-array surface EMG. Motor variability, assessed with 2 different variables (the centroid coordinates of the root mean square map and the dispersion variable), was evaluated during a low back muscle fatigue task. Test-retest reliability of muscle activity distribution was obtained using Pearson correlation coefficients. RESULTS A shift in the distribution of EMG amplitude toward the lateral-caudal region of the lumbar erector spinae induced by muscle fatigue was observed. Moderate to very strong correlations were found between both sessions in the last 3 phases of the fatigue task for both motor variability variables, whereas weak to moderate correlations were found in the first phases of the fatigue task only for the dispersion variable. CONCLUSION These findings show that, in asymptomatic participants, patterns of EMG activity are less reliable in initial stages of muscle fatigue, whereas later stages are characterized by highly reliable patterns of EMG activity.
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Affiliation(s)
- Jacques Abboud
- PhD Student, Université du Québec à Trois-Rivières, Département d'anatomie, Trois-Rivières, Quebec, Canada
| | - François Nougarou
- Postdoctoral Fellowship, Université du Québec à Trois-Rivières, Département des sciences de l'activité physique, Trois-Rivières, Quebec, Canada
| | - Michel Loranger
- Chiropractic Student, Université du Québec à Trois-Rivières, Département de chiropratique, Trois-Rivières, Quebec, Canada
| | - Martin Descarreaux
- Full Professor, Université du Québec à Trois-Rivières, Département des sciences de l'activité physique, Trois-Rivières, Quebec, Canada.
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