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1.
Artigo em Inglês | MEDLINE | ID: mdl-34855522

RESUMO

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.

2.
Sleep ; 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34432067

RESUMO

STUDY OBJECTIVES: Within-subject stability of certain sleep features across multiple nights is thought to reflect the trait-like behavior of sleep. However, to be considered a trait, a parameter must be both stable and robust. Here, we examined the stability (i.e., across the same sleep opportunity periods) and robustness (i.e., across sleep opportunity periods that varied in duration and timing) of different sleep parameters. METHODS: Sixty-eight military personnel (14 W) spent 5 nights in the sleep laboratory during a simulated military operational stress protocol. After an adaptation night, participants had an 8-hour sleep opportunity (23:00-07:00) followed by 2 consecutive nights of sleep restriction and disruption which included two 2-hour sleep opportunities (01:00-03:00; 05:00-07:00) and, lastly, another 8-hour sleep opportunity (23:00-07:00). Intra-class correlation coefficients were calculated to examine differences in stability and robustness across different sleep parameters. RESULTS: Sleep architecture parameters were less stable and robust than absolute and relative spectral activity parameters. Further, relative spectral activity parameters were less robust than absolute spectral activity. Absolute alpha and sigma activity demonstrated the highest levels of stability that were also robust across sleep opportunities of varying duration and timing. CONCLUSIONS: Stability and robustness varied across different sleep parameters, but absolute NREM alpha and sigma activity demonstrated robust trait-like behavior across variable sleep opportunities. Reduced stability of other sleep architecture and spectral parameters during shorter sleep episodes as well as across different sleep opportunities has important implications for study design and interpretation.

3.
Physiol Behav ; 236: 113413, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-33811909

RESUMO

PURPOSE: To study the impact of 48 h of simulated military operational stress (SMOS) on executive function, in addition to the role of trait resilience (RES) and aerobic fitness (FIT) on executive function performance. Associations between executive function and neuropeptide-Y (NPY), brain-derived neurotropic factor (BDNF), insulin-like growth factor-I (IGF-I), oxytocin, and α-klotho (klotho) were assessed to elucidate potential biomarkers that may contribute to cognitive performance during a multi-factorial stress scenario. METHODS: Fifty-four service members (SM) (26.4 ± 5.4 years, 178.0 ± 6.5 cm, 85.2 ± 14.0 kg) completed the 5-day protocol, including daily physical exertion and 48 h of restricted sleep and caloric intake. Each morning subjects completed a fasted blood draw followed by Cognition, a 10-part cognitive test battery assessing executive function. SMs were grouped into tertiles [low (L-), moderate (M-), high (H-)] based on Connor Davidson Resilience Score (RES) and V˙O2peak (FIT). Repeated measures ANOVA were run to analyze the effect of day on cognitive performance and biomarker concentration. Separate two-way mixed ANOVAs were run to determine the interaction of group by day on cognitive function. Friedman test with Bonferroni-corrected pairwise comparisons were used if assumptions for ANOVA were not met. Associations between changes in biomarkers and cognitive performance were analyzed using parametric and non-parametric correlation coefficients. RESULTS: SMOS reduced SM vigilance -11.3% (p < 0.001) and working memory -5.6% (p = 0.015), and increased risk propensity +9.5% (p = 0.005). H-RES and H-FIT SMs demonstrated stable vigilance across SMOS (p > 0.05). Vigilance was compromised during SMOS in L- and M-RES (p = 0.007 and p = 0.001, respectively) as well as L- and M-FIT (p = 0.001 and p = 0.031, respectively). SMOS reduced circulating concentrations of α-klotho -7.2% (p = 0.004), NPY -6.4% (p = 0.001), and IGF-I -8.1% (p < 0.001) from baseline through the end of the protocol. BDNF declined -19.2% after the onset of sleep and caloric restriction (p = 0.005) with subsequent recovery within 48 h. Oxytocin remained stable (p > 0.05). Several modest associations between neuroendocrine biomarkers and cognitive performance were identified. CONCLUSION: This study demonstrates H-FIT and H-RES may buffer the impact of SMOS on vigilance. SMOS negatively impacted circulating neuroendocrine biomarkers. While BDNF returned to baseline concentrations by the end of the 5 d protocol, NPY, IGF-I, and α-klotho may require a longer recovery period. These data suggest that the military may benefit by training and/or selection processes targeting at augmenting trait resilience and aerobic fitness for increased readiness.


Assuntos
Função Executiva , Militares , Biomarcadores , Cognição , Exercício Físico , Humanos , Memória de Curto Prazo , Aptidão Física
5.
Clin J Sport Med ; 30 Suppl 1: S61-S68, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32132479

RESUMO

OBJECTIVE: Symptom factors present during the first week following concussion may predict subsequent concussion outcomes and recovery duration. We hypothesized that a high loading on cognitive-fatigue-migraine and somatic factors would be predictive of neurocognitive impairment following concussion. We also hypothesized that the affective factor would be related to vestibular symptoms and impairment. DESIGN: Prospective repeated measures. SETTING: Concussion specialty clinic. PARTICIPANTS: Athletes aged 13 to 20 years diagnosed with a concussion within the past 7 days. INDEPENDENT VARIABLE: Symptom factors at the initial visit 1 to 7 days after injury. MAIN OUTCOME MEASURE: Symptom factor score, neurocognitive testing, and vestibular/ocular motor assessment at the second visit (2-4 weeks after injury). RESULTS: The somatic symptom factor from the initial visit was significant (P < 0.05) in all vestibular/ocular screening components (P < 0.05) but not neurocognitive test performance (P > 0.05) at the second visit. The cognitive-migraine-fatigue and affective symptom factors predicted symptom burden at the second visit (P < 0.001) but did not predict recovery time (P = 0.200). CONCLUSIONS: The somatic symptom factor during the first week after injury predicted symptom provocation during vestibular/ocular screening at 2 to 4 weeks after injury. Specifically, higher scores on somatic symptom factor at the initial visit predicted worse symptom reporting for all vestibular/ocular screening components at the second visit. Patients with higher scores on the cognitive-migraine-fatigue and affective symptom factors at the initial visit predicted total symptom burden at the second visit.


Assuntos
Traumatismos em Atletas/fisiopatologia , Concussão Encefálica/fisiopatologia , Transtornos Neurocognitivos/fisiopatologia , Recuperação de Função Fisiológica , Avaliação de Sintomas , Adolescente , Atletas , Traumatismos em Atletas/complicações , Concussão Encefálica/complicações , Transtornos Cognitivos/fisiopatologia , Fadiga/fisiopatologia , Feminino , Humanos , Masculino , Transtornos de Enxaqueca/fisiopatologia , Transtornos Neurocognitivos/etiologia , Síndrome Pós-Concussão/fisiopatologia , Estudos Prospectivos , Acompanhamento Ocular Uniforme/fisiologia , Movimentos Sacádicos/fisiologia , Fatores de Tempo , Doenças Vestibulares/fisiopatologia , Adulto Jovem
6.
Sleep Med Clin ; 15(1): 31-39, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32005348

RESUMO

Sleep has a widespread impact across different domains of performance, including sensorimotor function. From an ecological dynamics perspective, sensorimotor function involves the continuous and dynamic coupling between perception and action. Sport performance relies on sensorimotor function as successful movement behaviors require accurate and efficient coupling between perceptions and actions. Compromised sleep impairs different aspects of sensorimotor performance, including perceptual attunement and motor execution. Changes in sensorimotor performance can be related to specific features of sleep, notably sleep spindles and slow waves. One unaddressed area of study is the extent to which specific sleep features contribute to overall sport-specific performance.


Assuntos
Desempenho Atlético/fisiologia , Movimento/fisiologia , Sono/fisiologia , Esportes/fisiologia , Eletroencefalografia , Humanos
7.
J Head Trauma Rehabil ; 35(4): E361-E371, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32108712

RESUMO

OBJECTIVE: Determine whether preinjury concussion symptom factors predict postinjury concussion symptom factors. SETTING: Community concussion surveillance program between 2008 and 2017. PARTICIPANTS: A total of 290 high school and collegiate-aged athletes (n = 168, aged 14-17 years; n = 122, aged 18-21 years, respectively). DESIGN: Retrospective analysis. MAIN MEASURES: Post-Concussion Symptom Scale scores prior to and within 7 days of sustaining a sport-related concussion. METHODS: Post-Concussion Symptom Scale scores were aggregated into cognitive-sensory, sleep-arousal, vestibular-somatic, and affective preinjury symptom factors. These preinjury symptom factors, in conjunction with sex and previous concussion history, underwent linear regressions to predict cognitive-migraine-fatigue, somatic, sleep, and affective postinjury symptom factors. RESULTS: The cognitive-sensory factor (P = .002) and female sex (P = .002) predicted the postinjury cognitive-migraine-fatigue factor in combined age group but not stratified age group models. Among the 14 to 17 years age group, and not the 18 to 21 years age group, the preinjury sleep-arousal symptom factor predicted postinjury somatic (P = .003) and sleep factors (P = .005). The affective preinjury factor predicted the affective factor (P = .001) and somatic factor (P = .008) in the 18 to 21 years age group. A history of previous concussions also predicted the postinjury somatic symptom factor (P = .005). CONCLUSION: Preinjury symptom factors predicted postinjury symptom factors and age-associated differences in symptom factors may provide clinical value in prognostic models for subsequent postinjury clinical outcomes.


Assuntos
Traumatismos em Atletas , Concussão Encefálica , Síndrome Pós-Concussão , Adolescente , Atletas , Traumatismos em Atletas/diagnóstico , Traumatismos em Atletas/epidemiologia , Concussão Encefálica/complicações , Concussão Encefálica/diagnóstico , Concussão Encefálica/epidemiologia , Feminino , Humanos , Masculino , Testes Neuropsicológicos , Síndrome Pós-Concussão/diagnóstico , Síndrome Pós-Concussão/epidemiologia , Estudos Retrospectivos , Adulto Jovem
8.
J Sci Med Sport ; 22(12): 1292-1297, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31521485

RESUMO

OBJECTIVES: The current study investigated the role of persistent vestibular-ocular symptoms and impairment following sport-related concussion on recovery time and clinical outcomes among adolescents. DESIGN: Prospective cohort. METHODS: 50 (F-22/M-28) adolescents aged 12-20 years completed a vestibular-ocular motor screening, neurocognitive assessment, and the Post-Concussion Symptom Scale (PCSS) at clinical assessments conducted at 0-10 and 11-21 days after concussion. Participants were assigned to: 1) persistent vestibular-ocular (PERSIST), 2) vestibular-ocular improvement (IMPROVE), or 3) no vestibular-ocular impairment (NONE) groups based on vestibular-ocular motor screening conducted during each assessment. A 3 (GROUP) X 2 (TIME) ANOVA was performed on neurocognitive and symptom scores, and a between-subjects ANOVA was performed for recovery time. RESULTS: 49 subjects were identified among the PERSIST (n=17), IMPROVE (n=12) and NONE (n=20) groups. There were no neurocognitive performance differences between groups at 0-10 days post-concussion, but groups differed on PCSS at 11-21 days (p=.001), with the PERSIST (29.0±24.9) group reporting higher symptoms than the NONE (5.45±10.0; p=.005) group. The PERSIST group took significantly longer to recover (34.9±11.6 days) than the NONE (22.9±14.9 days) group (p=.03). All groups improved on verbal (p<.001) and visual memory (p=.028), visual motor speed (p=.005), and reaction time (p=.004) from 0-10 to 11-20 days following SRC and no significant group by time interactions for cognitive scores identified. CONCLUSIONS: Persistent post-concussion vestibular-ocular symptoms and impairment may influence neurocognitive performance and clinical recovery following sport-related concussion.


Assuntos
Traumatismos em Atletas/complicações , Concussão Encefálica/complicações , Transtornos da Motilidade Ocular/etiologia , Síndrome Pós-Concussão/diagnóstico , Doenças Vestibulares/etiologia , Adolescente , Traumatismos em Atletas/diagnóstico , Concussão Encefálica/diagnóstico , Criança , Feminino , Humanos , Masculino , Testes Neuropsicológicos , Transtornos da Motilidade Ocular/diagnóstico , Estudos Prospectivos , Tempo de Reação , Doenças Vestibulares/diagnóstico , Adulto Jovem
9.
Syst Rev ; 7(1): 244, 2018 12 23.
Artigo em Inglês | MEDLINE | ID: mdl-30580762

RESUMO

BACKGROUND: Musculoskeletal injuries (MSI) represent more than half of all injuries in tactical populations (i.e., military service and public safety workers including police, firefighters, emergency medical services (EMS)). Most lower extremity MSIs result from physical exertion during training, occupational tasks, and recreation. Such exertional lower extremity injuries (ELEI) produce a significant human and financial cost. Accordingly, significant efforts have been made to identify sensitive, specific, and reliable predictors of ELEI. There is a need to synthesize and evaluate the predictive value of risk factors for ELEI while addressing the influence of occupation, sex, exposure, injury characteristics, and study quality. Therefore, the purpose of this systematic review and planned meta-analysis is to evaluate risk factors for ELEI in tactical populations. METHODS: After the development of a search strategy, comprehensive searches will be conducted in MEDLINE, EMBASE, Cochrane, and CINAHL databases. Articles will be screened with a multi-user process and delimited to prospective comparative cohort studies that directly measure injury occurrence in the target population(s). Extracted data will be synthesized and assessed for reporting bias, meta-bias, and overall quality, with subgroup analyses to determine the influence of participant, injury, and exposure characteristics in addition to study quality. DISCUSSION: This systematic review and planned meta-analysis will comprehensively evaluate ELEI risk factors. Information gained will inform injury prevention protocols, facilitate the use of improved measurements, and identify requirements for future research. TRIAL REGISTRATION: The systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 3 Jan 2018 (registration number CRD42018056977 ).


Assuntos
Socorristas , Exercício Físico/fisiologia , Extremidade Inferior/lesões , Militares , Sistema Musculoesquelético/lesões , Traumatismos Ocupacionais/prevenção & controle , Humanos , Fatores de Risco
10.
Syst Rev ; 7(1): 73, 2018 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-29729666

RESUMO

BACKGROUND: Exertional lower body musculoskeletal injuries (ELBI) cost billions of dollars and compromise the readiness and job performance of military service and public safety workers (i.e., tactical populations). The prevalence and burden of such injuries underscores the importance of prevention efforts during activities necessary to sustain core occupational competencies. Attempts to synthesize prevention techniques specific to tactical populations have provided limited insight on the comparative efficacy of interventions that do not modify physical training practices. There is also a need to assess the influence of sex, exposure, injury classification scheme, and study design. Thus, the primary purpose of the systematic review and planned meta-analysis detailed in this protocol is to evaluate the comparative efficacy of ELBI prevention strategies in tactical populations. METHODS: A systematic search strategy will be implemented in MEDLINE, EMBASE, Cochrane, and CINAHL. A multi-tiered process will be used to capture randomized controlled trials and prospective cohort studies that directly assess the prevention of ELBI in tactical population(s). Extracted data will be used to compare prevention strategies and assess the influence of heterogeneity related to occupation, sex, exposure, injury characteristics, and study quality. In addition, individual risk of bias, meta-bias, and the quality of the body of evidence will be rigorously tested. DISCUSSION: This systematic review and planned meta-analysis will comprehensively evaluate ELBI mitigation strategies in tactical populations, elucidate factors that influence responses to treatment, and assess the overall quality of the body of research. Results of this work will guide the prioritization of ELBI prevention strategies and direct future research efforts, with direct relevance to tactical, health and rehabilitation science, and human performance optimization stakeholders. SYSTEMATIC REVIEW REGISTRATION: The systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 3 Jan 2018 (registration number CRD42018081799 ).


Assuntos
Socorristas , Extremidade Inferior/lesões , Militares , Sistema Musculoesquelético/lesões , Traumatismos Ocupacionais/prevenção & controle , Exercício Físico/fisiologia , Humanos , Prevalência , Ferimentos e Lesões/prevenção & controle
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