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1.
Eur J Sport Sci ; : 1-3, 2022 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-34937525

RESUMO

This issue of the European Journal of Sport Science includes 8 invited state-of-the-science narrative reviews by well-established researchers in the area of military performance focused on (a) physical training; (b) musculoskeletal injury; (c) adaptive bone formation and stress fracture prevention; (d) sex differences in responses to military stress; (e) load monitoring in military settings; (g) circulating biomarkers related to resilience during military stress; (H) military nutrition research; and (I) development of military exoskeletons. Important historical, current and future scientific and research information and guidance within the context of sustained and improved military physical performance and readiness are provided. Conclusions and recommendations for protecting Soldier health and resiliency include: (1) combined physical training emphasizing higher intensity but lower volume; (2) musculoskeletal injury risk factors most supported from the literature include: female sex, prior injury and low fitness; (3) adequate sleep, vitamin D, calcium, and energy availability are all critical for creating a resilient skeleton protecting against stress fractures; (4) differences between men and women when exposed to military stress include cardiovascular strain, fat oxidation, and psychological health risk; (5) biomarkers (cortisol, epi/norepi, ILs 4, 6, 10, 18 and TNF-alpha, IGF-I, testosterone, DHEA) offer insight for internal stress; (6) monitoring physiological training load should include consideration for multiple inputs, rather than a single measure; (7) nutrition optimization includes determining operational requirements, nutritional practices and nutrient delivery strategies; and (8) future generation exoskeletons will achieve a better balance of intended movement based on individual user and interactions with internal and external constraints.

2.
J Sci Med Sport ; 25(1): 89-94, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34507882

RESUMO

OBJECTIVES: To determine the physiological effects of multiple stressors including energy deficit during a 62-day Ranger course in a hot-humid environment. DESIGN: Prospective cohort design. METHODS: Food intake data were collected daily and energy expenditure at each of the three phases of the course was estimated by the doubly-labeled water method. Anthropometry, hydration status, stress and metabolic hormones, handgrip strength and lower explosive power were measured at the start and at the end of each phase. RESULTS: Seventeen male participants (age: 24.5 ±â€¯3.2 years, height: 173.9 ±â€¯5.1 cm, body mass: 69.3 ±â€¯3.2 kg, BMI: 22.9 ±â€¯0.9 kg/m2, percent body fat: 14 ±â€¯5%) completed the study. Mean total daily energy expenditure was 4756 kcal/day and mean daily energy intake was 3882 kcal/day. An 18% energy deficit resulted in an average body mass loss of 4.6 kg, comprising mostly fat mass. Participants with higher baseline adiposity (>15% body fat) lost more fat mass and gained (rather than lost) muscle mass compared to those with lower baseline adiposity. Handgrip strength declined only at the end of Phase I, while lower body explosive power declined progressively throughout the course. Lean mass in arms and legs was correlated with initial grip strength and lower body explosive power, but only at the start of the course. CONCLUSIONS: Physiologically demanding Ranger training in an equatorial environment is at least as metabolically demanding and stressful as other similar high-risk training courses, as demonstrated by the stress and metabolic endocrine responses, changes in body composition, and reduction in explosive power. Moreover, the smaller body size of Asian soldiers may confer an energetic advantage over larger sized Western counterparts.


Assuntos
Militares , Adulto , Composição Corporal , Ingestão de Energia , Metabolismo Energético , Força da Mão , Humanos , Masculino , Metaboloma , Desempenho Físico Funcional , Estudos Prospectivos , Adulto Jovem
3.
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.

4.
Percept Mot Skills ; : 315125211060953, 2021 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-34913749

RESUMO

The underlying mechanism(s) of the Bilateral Deficit (BLD) phenomenon is without consensus. Methodological inconsistencies across prior works may be an important source of equivocal results and interpretations. Based on repeatability problems with the BLD measure and maximal force definition, the presence or absence of the BLD phenomenon is altered, shifting conclusions of its mechanistic cause. Our purpose in this study was to examine methodological inconsistencies in applying the BLD measure to establish optimal methods for evaluating the underlying mechanism. Eleven healthy participants engaged in one familiarity and five test sessions, completing bilateral and unilateral elbow maximal voluntary isometric contractions. We defined maximal force by averaged and absolute peak and plateau values. BLD was evident if the bilateral index (BI), the ratio of the bilateral over summed unilateral forces, was statistically different from zero. We addressed interclass correlations (ICC), Chronbach's α, standard error of the mean, and minimal detectable change between and within sessions for all force measures and BI. We evaluated all combinations of sessions (i.e., 1-2, 3-5, 5-6) and maximal forces to establish the optimal number of sessions to achieve reliability. BLD was present for test sessions, but not for familiarization. All measures of maximal force were highly reliable between and within sessions (ICC(2,1) ≥ .895). BI was only considered significantly reliable in sessions 3-5 (p < .027), defined by absolute and average plateau forces, but reliability was still quantifiably poor (absolute: ICC(2,1) = .392; average: ICC(2,1) = .375). These results demonstrate that high force reliability within and between sessions does not translate to stable and reliable BI, potentially exposing the lack of any defined BLD mechanism.

5.
J Strength Cond Res ; 2021 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-34593729

RESUMO

ABSTRACT: Harty, PS, Friedl, KE, Nindl, BC, Harry, JR, Vellers, HL, and Tinsley, GM. Military body composition standards and physical performance: historical perspectives and future directions. J Strength Cond Res XX(X): 000-000, 2021-US military physique and body composition standards have been formally used for more than 100 years. These metrics promote appropriate physical fitness, trim appearance, and long-term health habits in soldiers, although many specific aspects of these standards have evolved as evidence-based changes have emerged. Body composition variables have been shown to be related to many physical performance outcomes including aerobic capacity, muscular endurance, strength and power production, and specialized occupational tasks involving heavy lifting and load carriage. Although all these attributes are relevant, individuals seeking to improve military performance should consider emphasizing strength, hypertrophy, and power production as primary training goals, as these traits appear vital to success in the new Army Combat Fitness Test introduced in 2020. This fundamental change in physical training may require an adjustment in body composition standards and methods of measurement as physique changes in modern male and female soldiers. Current research in the field of digital anthropometry (i.e., 3-D body scanning) has the potential to dramatically improve performance prediction algorithms and potentially could be used to inform training interventions. Similarly, height-adjusted body composition metrics such as fat-free mass index might serve to identify normal weight personnel with inadequate muscle mass, allowing for effective targeted nutritional and training interventions. This review provides an overview of the origin and evolution of current US military body composition standards in relation to military physical readiness, summarizes current evidence relating body composition parameters to aspects of physical performance, and discusses issues relevant to the emerging modern male and female warrior.

6.
Eur J Sport Sci ; : 1-15, 2021 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-34346851

RESUMO

Adaptation to military operational stress is a complex physiological response that calls upon the sympathetic nervous system (SNS), hypothalamic pituitary adrenal (HPA) axis and immune system, to create a delicate balance between anabolism and catabolism and meet the demands of an ever-changing environment. As such, resilience, the ability to withstand and overcome the negative impact of stress on military performance, is likely grounded in an appropriate biological adaptation to encountered stressors. Neuroendocrine [i.e. cortisol, epinephrine (EPI), norepinephrine (NE), neuropeptide-Y (NPY), and brain derived neurotropic factor (BDNF)], inflammatory [i.e. interleukin 6 (IL-6), IL-1ß, IL-4, IL-10 and tumour necrosis factor (TNF)-α], as well as growth and anabolic [i.e. insulin-like growth factor-I (IGF-I), testosterone, and dehydroepiandrosterone (DHEA)] biomarkers independently and interactively function in stress adaptations that are associated with a soldier's physical and psychological performance. In this narrative review, we detail biomarkers across neuroendocrine, inflammatory, and growth stimulating domains to better elucidate the biological basis of a resilient soldier. The findings from the reviewed studies indicate that military readiness and resiliency may be enhanced through better homeostatic control, better regulated inflammatory responses, and balanced anabolic/catabolic processes. It is unlikely that one class of biomarkers is better for assessing physiological resilience. Therefore, a biomarker panel that can account for appropriate balance across these domains may be superior in developing monitoring frameworks. Real-time physiological monitoring to assess biomarkers associated with resilience will be possible pending more sophisticated technologies and provide a field-expedient application for early identification and intervention of at-risk soldiers to improve military resiliency.

8.
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.

9.
Growth Horm IGF Res ; 59: 101407, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34118743

RESUMO

The purpose of this study was to examine the responses of growth hormone (GH) and insulin-like growth factor-I (IGFI) to intense heavy resistance exercise in highly trained men and women to determine what sex-dependent responses may exist. Subjects were highly resistance trained men (N = 8, Mean ± SD; age, yrs., 21 ± 1, height, cm, 175.3 ± 6.7, body mass, kg, 87.0 ± 18.5, % body fat, 15.2 ± 5.4, squat X body mass, 2.1 ± 0.4; and women (N = 7; Mean ± SD, age, yrs. 24 ± 5, height, cm 164.6 ± 6.7, body mass, kg 76.4 ± 8.8, % body fat, 26.9 ± 5.3, squat X body mass, 1.7 ± 0.6). An acute resistance exercise test protocol (ARET) consisted of 6 sets of 10 repetitions at 80% of the 1 RM with 2 min rest between sets was used as the stressor. Blood samples were obtained pre-exercise, after 3 sets, and then immediately after exercise (IP), 5, 15, 30, and 70 min post-exercise for determination of blood lactate (HLa), and plasma glucose, insulin, cortisol, and GH. Determination of plasma concentrations of IGFI, IGF binding proteins 1, 2, and 3 along with molecular weight isoform factions were determined at pre, IP and 70 min. GH significantly (P ≤ 0.05) increased at all time points with resting concentrations significantly higher in women. Significant increases were observed for HLa, glucose, insulin, and cortisol with exercise and into recovery with no sex-dependent observations. Women showed IGF-I values that were higher than men at all times points with both seeing exercise increases. IGFBP-1 and 2 showed increase with exercise with no sex-dependent differences. IGFBP-3 concentrations were higher in women at all-time points with no exercise induced changes. Both women and men saw an exercise induced increase with significantly higher values in GH in only the mid-range (30-60 kD) isoform.  Only women saw an exercise induced increase with significantly higher values for IGF fractions only in the mid-range (30-60 kD) isoform, which were significantly greater than the men at the IP and 70 min post-exercise time points. In conclusion, the salient findings of this investigation were that in highly resistance trained men and women, sexual dimorphisms exist but appear different from our prior work in untrained men and women and appear to support a sexual dimorphism related to compensatory aspects in women for anabolic mediating mechanisms in cellular interactions.

10.
J Sci Med Sport ; 24(10): 963-969, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33824080

RESUMO

OBJECTIVES: To provide an overall perspective on musculoskeletal injury (MSI) epidemiology, risk factors, and preventive strategies in military personnel. DESIGN: Narrative review. METHODS: The thematic session on MSIs in military personnel at the 5th International Congress on Soldiers' Physical Performance (ICSPP) included eight presentations on the descriptive epidemiology, risk factor identification, and prevention of MSIs in military personnel. Additional topics presented were bone anabolism, machine learning analysis, and the effects of non-steroidal anti-inflammatory drugs (NSAIDs) on MSIs. This narrative review focuses on the thematic session topics and includes identification of gaps in existing literature, as well as areas for future study. RESULTS: MSIs cause significant morbidity among military personnel. Physical training and occupational tasks are leading causes of MSI limited duty days (LDDs) for the U.S. Army. Recent studies have shown that MSIs are associated with the use of NSAIDs. Bone MSIs are very common in training; new imaging technology such as high resolution peripheral quantitative computed tomography allows visualization of bone microarchitecture and has been used to assess new bone formation during military training. Physical activity monitoring and machine learning have important applications in monitoring and informing evidence-based solutions to prevent MSIs. CONCLUSIONS: Despite many years of research, MSIs continue to have a high incidence among military personnel. Areas for future research include quantifying exposure when determining MSI risk; understanding associations between health-related components of physical fitness and MSI occurrence; and application of innovative imaging, physical activity monitoring and data analysis techniques for MSI prevention and return to duty.


Assuntos
Militares , Doenças Musculoesqueléticas/epidemiologia , Doenças Musculoesqueléticas/prevenção & controle , Ferimentos e Lesões/epidemiologia , Ferimentos e Lesões/prevenção & controle , Tomada de Decisão Clínica , Humanos , Incidência , Aprendizado de Máquina , Aptidão Física , Fatores de Risco , Estados Unidos/epidemiologia
11.
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
12.
Eur J Sport Sci ; : 1-34, 2021 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-33840352

RESUMO

Combat roles are physically demanding and expose service personnel to operational stressors such as high levels of physical activity, restricted nutrient intake, sleep loss, psychological stress, and environmental extremes. Women have recently integrated into combat roles, but our knowledge of the physical, physiological, and psycho-cognitive responses to these operational stressors in women is limited. The aim of this narrative review was to evaluate the evidence for sex-specific physical, physiological, and psycho-cognitive responses to real, and simulated, military operational stress. Studies examining physical and cognitive performance, body composition, metabolism, hypothalamic-pituitary-gonadal axis, and psychological health outcomes were evaluated. These studies report that women expend less energy and lose less body mass and fat-free mass, but not fat mass, than men. Despite having similar physical performance decrements as men during operational stress, women experience greater physiological strain than men completing the same physical tasks, but this may be attributed to differences in fitness. From limited data, military operational stress suppresses hypothalamic-pituitary-gonadal, but not hypothalamic-pituitary-adrenal, axis function in both sexes. Men and women demonstrate different psychological and cognitive responses to operational stress, including disturbances in mood, with women having a higher risk of post-traumatic stress symptoms compared with men. Based on current evidence, separate strategies to maximize selection and combat training are not warranted until further data directly comparing men and women are available. However, targeted exercise training programs may be advisable to offset the physical performance gap between sexes and optimize performance prior to inevitable declines caused by intense military operations.

14.
Eur J Sport Sci ; 21(1): 36-44, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32013782

RESUMO

Perceptual-motor coordination relies on the accurate coupling of the perceptual and movement systems. However, individuals must also be able to recalibrate to perturbations to perceptual and movement capabilities. We examined the effects of fatigue and load carriage on perceptual-motor coordination for a maximal leaping task. 23 participants completed an incremental fatigue protocol (light to fatiguing intensity stages) on two separate occasions (loaded/unloaded). At baseline and the end of every stage of the protocol, participants made perceptual judgments for the affordance of leaping. The accuracy of responses and reaction times were calculated and mean differences were assessed across exercise intensity and load carriage conditions. No interaction of exercise intensity and load carriage was detected, or main effect of load carriage. A main, quadratic effect of exercise intensity was detected on reaction times, with times decreasing through the moderate stage and increasing through post-fatigue. No effect of exercise/fatigue was detected on perceptual accuracy. The results indicate that exercise at high intensities through fatigue has a significant effect on perceptual-motor calibration. Contrastingly, in response to an action-scaled task, individuals can adequately recalibrate to increased load carriage.


Assuntos
Exercício Físico/fisiologia , Fadiga/fisiopatologia , Movimento/fisiologia , Desempenho Psicomotor/fisiologia , Suporte de Carga/fisiologia , Adulto , Fatores Etários , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Percepção , Tempo de Reação , Exercício de Aquecimento/fisiologia , Adulto Jovem
15.
Spinal Cord ; 59(1): 34-43, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32908194

RESUMO

STUDY DESIGN: Pilot nonrandomized clinical trial. OBJECTIVES: To examine the feasibility, acceptability, and preliminary efficacy of performing handcycling high-intensity interval training (HIIT) for 6 weeks in wheelchair users with spinal cord injury. SETTING: Participant's home. METHODS: Participants completed pre- and postgraded exercise stress tests, exercise surveys and 6 weeks of handcycling HIIT. The HIIT program consisted of two weekly, 25 min supervised at-home sessions (2-3 min warm-up, then ten intervals of cycling with a ratio of 1 min work at 90% peak power output (PPO) to 1 min recovery at 0-20% PPO, then 2-3 min cool down). Real-time power output and heart rate were recorded via sensors and a bike computer. The sensor data were analyzed to evaluate training efficacy. RESULTS: Seven of the ten enrolled participants (70%) completed the study. All but one completed the required 12 sessions. The participants met at least 1 of the HIIT target intensity criteria in 76 out of 89 total sessions (85.4%) performed. Participants expressed a high level of enjoyment on the Physical Activity Enjoyment Scale, mean (SD) = 114.8 (11.3), and satisfaction with the overall experience. Five of the seven participants (71%) who completed the study felt an increase in endurance, function, and health. Objective physiological changes showed mixed results. CONCLUSIONS: Six weeks of handcycling HIIT appears to be safe, feasible and acceptable. A longer HIIT work interval may be needed to elicit significant physiological responses. Future investigation of the feasibility and efficacy of differing HIIT parameters is needed.


Assuntos
Treinamento Intervalado de Alta Intensidade , Traumatismos da Medula Espinal , Exercício Físico , Estudos de Viabilidade , Feminino , Humanos , Masculino , Consumo de Oxigênio , Traumatismos da Medula Espinal/terapia
16.
Clin J Sport Med ; 31(3): 273-280, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30829684

RESUMO

BACKGROUND: After a concussion, athletes may be at increased risk of musculoskeletal injuries. Altered perception of action boundaries (ABP), or the limits of one's action capabilities, is one possible mechanism for this increase in injury risk after concussion. OBJECTIVE: To evaluate differences in symptoms, neurocognitive, vestibular/oculomotor, and action boundary function between subjects with no concussion history (NoHx) and concussion history (ConcHX). DESIGN: Cross-sectional study. SETTING: Laboratory at the University of Pittsburgh. PARTICIPANTS: ConcHx (n = 22; age: 21.8 ± 3.0 years, height: 174.0 ± 8.3 cm, and mass: 77.8 ± 14.8 kg) and NoHx athletes (n = 24; age: 21.6 ± 2.0 years, height: 176.0 ± 10.0 cm, and mass: 72.0 ± 15.3 kg). INTERVENTION: Immediate Postconcussion Assessment and Cognitive Testing (ImPACT) and Post-Concussion Symptom Scale (PCSS), Vestibular-Ocular Motor Screening (VOMS) tool, and the Perception-Action Coupling Task (PACT). The PACT measures the accuracy of ABP. MAIN OUTCOME MEASURES: Neurocognitive domain scores, PCSS, VOMS subdomain symptom gain, ABP accuracy, and actualization. RESULTS: ConcHx reported 2.7 ± 1.5 previous concussions occurring on average 263.8 ± 228.9 days prior. ConcHx was higher on several VOMS items including vertical/horizontal saccades (P = 0.001; P = 0.05), vertical/horizontal vestibular-ocular reflex (P < 0.001; P = 0.04), and visual motion sensitivity (P < 0.001). Average PACT movement time (P = 0.01) and reaction time (P = 0.01) were longer in ConcHx. CONCLUSIONS: These findings provide preliminary support for impaired vestibular/oculomotor function and ABP in ConcHx compared with NoHx. The current results may enhance our understanding of the mechanisms for increased musculoskeletal injury risk after concussion.


Assuntos
Traumatismos em Atletas , Concussão Encefálica , Percepção , Adulto , Traumatismos em Atletas/diagnóstico , Traumatismos em Atletas/fisiopatologia , Biomarcadores , Concussão Encefálica/diagnóstico , Concussão Encefálica/fisiopatologia , Estudos Transversais , Humanos , Testes Neuropsicológicos , Adulto Jovem
17.
Artigo em Inglês | MEDLINE | ID: mdl-32973684

RESUMO

Purpose: To determine if acute resistance exercise-induced increases in growth hormone (GH) and insulin-like growth factor-I (IGF-I) were differentially responsive for one or more molecular weight (MW) isoforms and if these responses were sex-dependent. Methods: College-aged men (n = 10) and women (n = 10) performed an acute resistance exercise test (ARET; 6 sets, 10 repetition maximum (10-RM) squat, 2-min inter-set rest). Serum aliquots from blood drawn Pre-, Mid-, and Post-ARET (0, +15, and +30-min post) were processed using High Performance Liquid Chromatography (HPLC) fractionation and pooled into 3 MW fractions (Fr.A: >60; Fr.B: 30-60; Fr.C: <30 kDa). Results: We observed a hierarchy of serum protein collected among GH fractions across all time points independent of sex (Fr.C > Fr.A > Fr.B, p ≤ 0.03). Sex × time interactions indicated that women experienced earlier and augmented increases in all serum GH MW isoform fraction pools (p < 0.05); however, men demonstrated delayed and sustained GH elevations (p < 0.01) in all fractions through +30-min of recovery. Similarly, we observed a sex-independent hierarchy among IGF-I MW fraction pools (Fr.A > Fr.B > Fr.C, p ≤ 0.01). Furthermore, we observed increases in IGF-I Fr. A (ternary complexes) in men only (p ≤ 0.05), and increases in Fr.C (free/unbound IGF-I) in women only (p ≤ 0.05) vs. baseline, respectively. Conclusions: These data indicate that the processing of GH and IGF-I isoforms from the somatotrophs and hepatocytes are differential in their response to strenuous resistance exercise and reflect both temporal and sex-related differences.


Assuntos
Hormônio do Crescimento Humano/sangue , Fator de Crescimento Insulin-Like I/metabolismo , Isoformas de Proteínas/sangue , Treinamento de Força , Adulto , Feminino , Humanos , Masculino , Fatores Sexuais , Adulto Jovem
18.
Behav Med ; 46(3-4): 290-301, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32787719

RESUMO

This research examines resilience from both cognitive and physiological perspectives and the relative importance of resilience for progression within an extremely physical training environment for 116 individuals. Our study provides a unique contribution as an examination of the combined effects of psychological and physiological resilience in the success of individuals in the first phase of a military special operations training course, the Navy's Basic Underwater Demolition/SEAL (BUD/S) course. Our study used the Connor-Davidson Resilience Scale (CD-RISC) for the psychological assessment and a blood sample to measure the concentrations of cortisol, DHEA and BDNF, each associated with stress adaptation and neuronal integrity. Our contributions include: heeding the call for more extensive research for resilience, examining physiological markers as predictors in training situations, combining psychological and physiological resilience into a single metric to assess resilience, and providing empirical support for the vital role of resilience in both stamina and persistence in training. Our findings indicate that both psychological and physiological resilience can be important predictors of persistence individually, but combining the measures provides a more holistic view to predict the success of an individual in this intensive training program. The present study has implications not only for the military community, but also for those individuals seeking elite performance in a broad array of fields, like professional athletes, CEO's, and emergency response workers.


Assuntos
Militares/psicologia , Resiliência Psicológica/ética , Adaptação Psicológica , Adulto , Fator Neurotrófico Derivado do Encéfalo/análise , Fator Neurotrófico Derivado do Encéfalo/sangue , Causalidade , Desidroepiandrosterona/análise , Desidroepiandrosterona/sangue , Análise Fatorial , Humanos , Hidrocortisona/análise , Hidrocortisona/sangue , Masculino , Prognóstico , Psicometria/métodos , Reprodutibilidade dos Testes , Inquéritos e Questionários
19.
Exerc Sport Sci Rev ; 48(3): 140-148, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32568926

RESUMO

We review evidence supporting an updated mechanostat model in bone that highlights the central role of osteocytes within bone's four mechanoadaptive pathways: 1) formation modeling and 2) targeted remodeling, which occur with heightened mechanical loading, 3) resorption modeling, and 4) disuse-mediated remodeling, which occur with disuse. These four pathways regulate whole-bone stiffness in response to changing mechanical demands.


Assuntos
Regeneração Óssea , Reabsorção Óssea , Osteócitos/fisiologia , Adaptação Fisiológica , Animais , Fenômenos Biomecânicos , Osso Cortical/fisiologia , Humanos , Estresse Mecânico , Suporte de Carga/fisiologia
20.
J Strength Cond Res ; 2020 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-32569125

RESUMO

Beckner, ME, Pihoker, AA, Darnell, ME, Beals, K, Lovalekar, M, Proessl, F, Flanagan, SD, Arciero, PJ, Nindl, BC, and Martin, BJ. Effects of multi-ingredient preworkout supplements on physical performance, cognitive performance, mood state, and hormone concentrations in recreationally active men and women. J Strength Cond Res XX(X): 000-000, 2020-Performance enhancement supplement research has primarily focused on the effectiveness of individual ingredients, rather than the combination. This study investigated the acute effects of 2 multi-ingredient preworkout supplements (MIPS), with beta-alanine and caffeine (BAC) and without (NBAC), compared with placebo (PLA) on anaerobic performance, endurance capacity, mood state, cognitive function, vascular function, and anabolic hormones. Thirty exercise-trained individuals (24.4 ± 4.9 years, 15 men and 15 women) completed a fatiguing exercise protocol on 3 separate occasions, 30 minutes after ingestion of BAC, NBAC, or PLA. Outcomes were analyzed using one-way or two-way repeated-measures analysis of variance, as appropriate (alpha = 0.05). Anaerobic power was greater when supplementing with NBAC (10.7 ± 1.2 W·kg) and BAC (10.8 ± 1.4 W·kg) compared with PLA (10.4 ± 1.2 W·kg) (p = 0.014 and p = 0.022, respectively). BAC improved V[Combining Dot Above]O2peak time to exhaustion (p = 0.006), accompanied by an increase in blood lactate accumulation (p < 0.001), compared with PLA. Both NBAC and BAC demonstrated improved brachial artery diameter after workout (p = 0.041 and p = 0.005, respectively), but PLA did not. L-arginine concentrations increased from baseline to postsupplement consumption of BAC (p = 0.017). Reaction time significantly decreased after exercise for all supplements. There was no effect of supplement on mood states. Exercise-trained individuals looking to achieve modest improvements in power and endurance may benefit from consuming MIPS before exercise.

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