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1.
Percept Mot Skills ; 129(1): 47-62, 2022 Feb.
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.


Assuntos
Cotovelo , Músculo Esquelético , Eletromiografia , Humanos , Contração Isométrica , Reprodutibilidade dos Testes
3.
Sports Biomech ; : 1-9, 2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34134606

RESUMO

Softball pitchers often pitch several games within a day and over consecutive days during a competitive season. High volumes of pitches thrown can decrease muscular strength, resulting in less proximal force generation and upper extremity compensation to maintain performance. Therefore, the purpose of this study was to assess upper and lower extremity muscular strength after pitching in a simulated game. Fourteen softball pitchers (17.9 ± 2.3 years, 166.4 ± 8.7 cm, 72.2 ± 12.6 kg) completed baseline isokinetic strength assessment for knee, hip, trunk and pitching elbow flexion and extension as well as trunk rotation. Seven days later, participants pitched a simulated game consisting of 105 fastballs prior to repeating all strength assessments. Changes in muscular strength were assessed using paired samples t-tests, with significance set a priori as p ≤ 0.05. Normalised (%BW) stride leg knee extension peak torque was significantly higher (p = 0.020) post-simulated game (75.1 ± 24.6%BW) as compared to baseline (64.0 ± 19.5%BW) and trunk flexion peak torque was significantly higher (p = 0.009) post-simulated game (84.8 ± 47.0%BW) as compared to baseline (63.5 ± 47.1%BW). This study showed an increase in knee extension and trunk flexion strength after an acute bout of pitching. The findings give insight into muscular changes following pitching which can assist in appropriate softball training and recovery.

4.
Artigo em Inglês | MEDLINE | ID: mdl-34180650

RESUMO

BACKGROUND: Windmill softball pitching is a highly skilled movement, combining whole body coordination with explosive force. Successful pitching requires sequential movement to transfer energy produced by the lower extremity to the pitching arm. Therefore, drive leg ground reaction force (GRF) and the time over which a pitcher can develop force during push off, defined as rate of force development (RFD), is essential for optimal performance. The purpose of this study was to examine GRF and RFD in the drive leg during the windmill softball pitch, as well as pitch velocity, throughout a simulated game. METHODS: Fourteen softball pitchers (17.9±2.3 years, 166.4±8.7cm, 72.2±12.6kg) pitched a simulated game. Pitch velocity and anterior-posterior and vertical GRF and RFD, each normalized to body weight, were collected for each inning. Average pitch speed remained consistent across all seven innings, 49.57±0.42mph. Changes in GRF and RFD were assessed, with level of significance set as p<0.05. RESULTS: A one-way repeated measures analysis of variance showed no significant differences in apGRF%BW (p=0.297), vGRF%BW (p=0.574), apRFD (BW/s) (p=0.085) and vRFD (BW/s) (p=0.059). CONCLUSIONS: Training programs can be improved with the knowledge of the magnitude and rate in which forces are developed by the drive leg during push-off of the windmill softball pitch.

5.
J Appl Biomech ; 37(4): 343-350, 2021 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-34051696

RESUMO

The objective was to examine the interactive effects of load magnitude and locomotion pattern on lower-extremity joint angles and intralimb coordination in recruit-aged women. Twelve women walked, ran, and forced marched at body weight and with loads of +25%, and +45% of body weight on an instrumented treadmill with infrared cameras. Joint angles were assessed in the sagittal plane. Intralimb coordination of the thigh-shank and shank-foot couple was assessed with continuous relative phase. Mean absolute relative phase (entire stride) and deviation phase (stance phase) were calculated from continuous relative phase. At heel strike, forced marching exhibited greater (P < .001) hip flexion, knee extension, and ankle plantar flexion compared with running. At mid-stance, knee flexion (P = .007) and ankle dorsiflexion (P = .04) increased with increased load magnitude for all locomotion patterns. Forced marching (P = .009) demonstrated a "stiff-legged" locomotion pattern compared with running, evidenced by the more in-phase mean absolute relative phase values. Running (P = .03) and walking (P = .003) had greater deviation phase than forced marching. Deviation phase increased for running (P = .03) and walking (P < .001) with increased load magnitude but not for forced marching. With loads of >25% of body weight, forced marching may increase risk of injury due to inhibited energy attenuation up the kinetic chain and lack of variability to disperse force across different supportive structures.


Assuntos
Marcha , Caminhada , Idoso , Fenômenos Biomecânicos , Feminino , Humanos , Articulação do Joelho , Extremidade Inferior
6.
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
7.
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
9.
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
10.
J Strength Cond Res ; 35(1): 212-220, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-29461421

RESUMO

ABSTRACT: Nagle Zera, J, Nagle, EF, Nagai, T, Lovalekar, M, Abt, JP, and Lephart, SM. Tethered swimming test: reliability and the association with swimming performance and land-based anaerobic performance. J Strength Cond Res 35(1): 212-220, 2021-The purpose of this study was 3-fold: (a) to examine the test-retest reliability of a 30-second maximal tethered freestyle swimming test (TST), (b) to assess the validity of the TST by examining the association with sprint swimming performance, and (c) to examine the associations between a swim-specific and land-based measure of anaerobic performance. A total of 29 male and female swimmers were recruited to participate in the study. Each subject completed a Wingate Anaerobic cycling test (WAnT), 2 or 4 TST, and a 22.9 m (25 yd), 45.7 m (50 yd), and 91.4 m (100 yd) maximal freestyle performance swims (PS). Mean and peak force (Fmean and Fpeak) were recorded for both the WAnT and TST, and average swimming velocity and time were recorded for the PS. In addition, physiological and perceptual measures were recorded immediately postexercise for all tests. The results of the present investigation showed strong intersession and intrasession reliability (R = 0.821-0.975; p < 0.001) for force parameters of the TST. Moderate correlations were found between Fmean and PS time and velocity of all distances, with slightly weaker correlations between Fpeak and the 22.9 m (time and velocity) and 45.7 m (velocity) PS. Finally, moderate correlations were found for Fmean and Fpeak of the TST and WAnT. This study demonstrated that the TST is a reliable measure, with moderate association with swimming performance, producing similar physiological responses compared with free swimming. Therefore, future research should focus on investigating the potential benefits of using the TST as a regular assessment tool as a part of a competitive swimming training program to track adaptations and inform training decisions.


Assuntos
Adaptação Fisiológica , Natação , Anaerobiose , Feminino , Humanos , Masculino , Reprodutibilidade dos Testes
11.
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.

12.
J Sports Sci ; 38(15): 1799-1805, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32412332

RESUMO

Clinically feasible metrics, that can inform the concussion recovery decision making process by evaluating a unique domain beyond current testing domains (e.g., balance, neurocognition, symptoms, vestibular/ocular function) are still in need. The purpose of this study was to compare perceptual-motor control in adolescent athletes ≤21 days of sport-related concussion and healthy controls and evaluate the association of perceptual-motor control to the outcomes of commonly-used sport-related concussion clinical assessments. Athletes (age: 12-18 years) with sport-related concussion (n = 48) and healthy controls (n = 24) completed the Perception-Action Coupling Task (PACT), whose outcomes are mean reaction, movement, initiation, response time, and accuracy. ImPACT outcomes are verbal/visual memory scores, motor processing speed, and reaction time. Vestibular-Ocular Motor Screen (VOMS) outcomes are symptoms from: smooth pursuit, horizontal/vertical saccades, near-point of convergence, horizontal/vestibular ocular-reflex, and visual motion sensitivity. CONCUSSED demonstrated ~5% deficit in overall perceptual-motor accuracy during PACT compared to CONTROLS (p = 0.03). PACT accuracy negatively correlated with smooth pursuits(r = -0.29), and horizontal (r = -0.35)/vertical (r = -0.30) saccades. The C5.0 decision tree determined PACT accuracy was the most relevant predictor of sport-related concussion when no visual motion sensitivity symptoms were reported and Visual Memory was >66. Perceptual-motor control tests may complement current sport-related concussion assessments when neurocognition and vestibular/ocular motor system are not grossly impaired.


Assuntos
Traumatismos em Atletas/diagnóstico , Concussão Encefálica/diagnóstico , Testes Neuropsicológicos , Adolescente , Traumatismos em Atletas/fisiopatologia , Concussão Encefálica/fisiopatologia , Criança , Cognição/fisiologia , Estudos Transversais , Árvores de Decisões , Humanos , Memória/fisiologia , Destreza Motora/fisiologia , Músculos Oculomotores/fisiologia , Percepção/fisiologia , Tempo de Reação , Vestíbulo do Labirinto/fisiologia
13.
J Neurotrauma ; 37(19): 2102-2112, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32340548

RESUMO

Mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD) are common in military populations and share numerous symptoms. Functional graph theory studies demonstrate altered small-world brain networks in mTBI and PTSD, but little is known about structural covariance networks or the potentially distinct topology of mTBI-PTSD comorbidity. The purpose of this study was to compare brain structural covariance networks in healthy active duty military service members (CON) to those with PTSD, mTBI, and mTBI-PTSD. Seventy-six service members (31 CON, 14 PTSD, 12 mTBI, 19 mTBI-PTSD) completed clinical questionnaires and structural magnetic resonance imaging scans. Cortical thickness-derived adjacency matrices were used to determine structural covariance network topologies. Pairwise comparisons for characteristic path length, clustering coefficient, modularity (global), closeness centrality (nodal), and local efficiency were made across a range of network densities (5-35%) using non-parametric permutation tests. All clinical groups showed greater levels of arousal, stress, anxiety, and depression compared with CON. Global network analysis revealed greater clustering and local efficiency in PTSD compared with CON, whereas nodal analysis indicated altered path lengths and closeness centrality in fronto-limbic areas with mTBI-PTSD. Global and nodal graph outcomes suggest distinct pathophysiological manifestations of mTBI, PTSD, and mTBI-PTSD in structural brain networks. Greater network segregation and nodal differences in fronto-limbic areas may be tied to emotional fluctuations.


Assuntos
Concussão Encefálica/diagnóstico por imagem , Concussão Encefálica/psicologia , Militares , Transtornos de Estresse Pós-Traumáticos/diagnóstico por imagem , Transtornos de Estresse Pós-Traumáticos/etiologia , Adulto , Concussão Encefálica/fisiopatologia , Estudos de Casos e Controles , Conectoma , Estudos Transversais , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Transtornos de Estresse Pós-Traumáticos/fisiopatologia , Inquéritos e Questionários , Estados Unidos
14.
J Sci Med Sport ; 23(10): 932-936, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32340794

RESUMO

OBJECTIVES: The purpose of this analysis was to describe and compare the incidence and pattern of musculoskeletal injuries in women and men during the United States Marine Corps Ground Combat Element Integrated Task Force work-up and assessment phases in sex-integrated units. DESIGN: Descriptive cross-sectional study. METHODS: Certified athletic trainers and Navy corpsmen reported injury data for 302 Marines (women: 27.8%, men: 72.2%). Injury frequency, location, cause, type, and activity during injury were described. Fisher's exact tests were used to compare proportions of injured women and men. The cost of injuries was calculated using the Web-based Injury Statistics Query and Reporting System. RESULTS: A greater proportion of women (40.5%) sustained an injury compared with men (18.8%, p < 0.001). The lower extremity was the most frequent location for injury (women: 68% of injuries, men: 60%). The most frequent sub-location was the hip (24%) in women and foot/toes (26%) in men. Marching under load was the most common cause (women: 64%, men: 48%). Most injuries occurred during physical training (women: 78%, men: 66%), and were classified as pain/spasm/ache (women: 56%, men: 36%). The total lifetime cost of these injuries that occurred among 302 Marines was approximately $1.4 million U.S. dollars. CONCLUSIONS: The high risk of lower extremity injuries that occurred while marching under load during physical training, and the greater risk of injuries among women compared to men, indicates the need for further research to identify the components of combat Military Occupational Specialty specific training that could be modified to mitigate injuries.


Assuntos
Militares/estatística & dados numéricos , Sistema Musculoesquelético/lesões , Traumatismos Ocupacionais/epidemiologia , Estudos Transversais , Feminino , Humanos , Incidência , Masculino , Fatores Sexuais , Estados Unidos/epidemiologia
15.
J Appl Biomech ; : 1-6, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31914419

RESUMO

Warfighter performance may be compromised through the impact of load carriage on dynamic postural stability. Men and women may experience this impact to differing extents due to postural stability differences. Therefore, the authors investigated the effect of load magnitude on dynamic postural stability in men and women during a landing and stabilization task. Dynamic postural stability of 32 subjects (16 women) was assessed during the unilateral landing of submaximal jumps under 3 load conditions: +0%, +20%, and +30% body weight. Dynamic postural stability was measured using the dynamic postural stability index, which is calculated from ground reaction force data sampled at 1200 Hz. Two-way mixed-measures analysis of variance compared dynamic postural stability index scores between sexes and loads. Dynamic postural stability index scores were significantly affected by load (P = .001) but not by sex or by the sex by load interaction (P > .05). Dynamic postural stability index scores increased between the 0% (0.359 ± 0.041), 20% (0.396 ± 0.034), and 30% (0.420 ± 0.028) body weight conditions. Increased load negatively affects dynamic postural stability with similar performance decrements displayed by men and women. Men and women warfighters may experience similar performance decrements under load carriage conditions of similar relative magnitudes.

16.
J Athl Train ; 54(5): 497-504, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31074634

RESUMO

CONTEXT: Ankle injury is one of the most common conditions in athletics and military activities. Strength asymmetry (SA) and imbalance may represent a risk factor for injury, but past investigations have produced ambiguous conclusions. Perhaps one explanation for this ambiguity is the fact that these authors used univariate models to predict injury. OBJECTIVE: To evaluate the predictive utility of SA and imbalance calculations for ankle injury in univariate and multivariate prediction models. DESIGN: Prospective cohort study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 140 male US Air Force Special Forces. MAIN OUTCOME MEASURE(S): Baseline testing consisted of body composition, isometric strength, and aerobic and anaerobic capacity. A clinician conducted medical chart reviews 365 days posttesting to document the incidence of ankle injury. Strength asymmetries were calculated based on the equations most prevalent in the literature along with known physiological predictors of injury in the military: age, height, weight, body composition, and aerobic capacity. Simple logistic regression was conducted using each predictor, and backward stepwise logistic regression was conducted with each equation method and the physiological predictors entered initially into the model. RESULTS: Strength asymmetry or imbalance or both, as a univariate predictor, was not able to predict ankle injury 365 days posttesting. Body mass (P = .01) and body mass index (P = .01) significantly predicted ankle injury. Strength asymmetry or imbalance or both significantly predicted ankle injury when considered with body mass (P = .002-.008). CONCLUSIONS: As a univariate predictor, SA did not predict ankle injury. However, SA contributed significantly to predicting ankle injury in a multivariate model using body mass. Interpreting SA and imbalance in the presence of other physiological variables can help elucidate the risk of ankle injury.


Assuntos
Traumatismos do Tornozelo , Traumatismos em Atletas , Militares , Força Muscular/fisiologia , Equilíbrio Postural/fisiologia , Adulto , Traumatismos do Tornozelo/epidemiologia , Traumatismos do Tornozelo/etiologia , Traumatismos do Tornozelo/fisiopatologia , Traumatismos do Tornozelo/prevenção & controle , Traumatismos em Atletas/epidemiologia , Traumatismos em Atletas/fisiopatologia , Traumatismos em Atletas/prevenção & controle , Índice de Massa Corporal , Feminino , Humanos , Incidência , Masculino , Valor Preditivo dos Testes , Estudos Prospectivos , Esportes/fisiologia , Estados Unidos
17.
J Strength Cond Res ; 33(5): 1208-1215, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31034459

RESUMO

Nagle, EF, Nagai, T, Beethe, AZ, Lovalekar, MT, Zera, JN, Connaboy, C, Abt, JP, Beals, K, Nindl, BC, Robertson, RJ, and Lephart, SM. Reliability and validity of a pool-based maximal oxygen uptake test to examine high-intensity short-duration freestyle swimming performance. J Strength Cond Res 33(5): 1208-1215, 2019-A modality-specific swimming protocol to assess maximal oxygen uptake (V[Combining Dot Above]O2maxsw) is essential to accurately prescribe and monitor swimming conditioning programs. Consequently, there is a need for a reliable and valid graded intensity swimming pool test to accurately assess V[Combining Dot Above]O2maxsw using indirect calorimetry. The purpose of this study was to assess (a) reliability of an intensity self-regulated swimming pool test of V[Combining Dot Above]O2maxsw and (b) validity of a V[Combining Dot Above]O2maxsw test using performance swim (PS) time as the criterion. Twenty-nine men (n = 15) and women (n = 14) (age, 23 ± 6.4 years; body mass index, 23.5 ± 3.0 kg·m) performed 2 swimming pool V[Combining Dot Above]O2maxsw trials (V[Combining Dot Above]O2maxsw A and V[Combining Dot Above]O2maxsw B), and 2 PS tests (45.7 m [31.20 ± 4.5 seconds] and 182 m [159.2 ± 25.5 seconds]). For test-retest reliability (trials A vs. B), strong correlations (p < 0.05) were found for V[Combining Dot Above]O2maxsw (ml·kg·min) (r = 0.899), O2 pulse (ml O2·beat) (r = 0.833), and maximum expired ventilatory volume (L·min) (r = 0.785). For performance validity, moderately strong correlations (p < 0.05) were found between V[Combining Dot Above]O2maxsw A and 45.7-m (r = -0.543) and 182-m (r = -0.486) swim times. The self-regulated graded intensity swimming pool protocol examined presently is a reliable and valid test of V[Combining Dot Above]O2maxsw. Studies should consider the suitability of a V[Combining Dot Above]O2maxsw test for military personnel, clinical populations, and injured athletes.


Assuntos
Calorimetria Indireta/métodos , Teste de Esforço/métodos , Consumo de Oxigênio , Natação/fisiologia , Adolescente , Adulto , Desempenho Atlético , Feminino , Frequência Cardíaca , Humanos , Masculino , Ventilação Voluntária Máxima , Reprodutibilidade dos Testes , Fatores de Tempo , Adulto Jovem
18.
Orthop J Sports Med ; 7(3): 2325967119831272, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30891463

RESUMO

Background: Musculoskeletal injuries at the shoulder are highly prevalent and place a large burden on United States Special Forces personnel. Literature is lacking regarding the risk factors for these types of injuries. Purpose/Hypothesis: The purpose of this study was to evaluate the association of shoulder strength and kinematic characteristics, which have shown retrospective associations with shoulder conditions/injuries, with prospectively collected shoulder injuries. We hypothesized that lower strength and abnormal kinematics would be predictive of future shoulder injury. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 140 male Special Forces operators underwent a musculoskeletal evaluation of the shoulder that included a scapular kinematic assessment during a humeral elevation task and isokinetic strength testing of the scapular protractors/retractors, external/internal rotators, and elevators of the shoulder. From strength assessments, ipsilateral strength ratios and bilateral strength asymmetries were also calculated. Musculoskeletal injuries of the shoulder were collected prospectively by use of medical chart reviews at 365 days following the evaluation. Separate generalized estimating equations (GEEs) and simple logistic regressions were used to analyze the association between baseline predictors and development of shoulder injury. Results: Results of the GEEs showed no significant prediction of shoulder injury by shoulder strength (odds ratio [OR], 1.00-1.03), ipsilateral strength ratios (OR, 0.43-2.12), or scapular kinematics (OR, 0.99-1.01). Logistic regression indicated that none of the bilateral asymmetries were significantly predictive of shoulder injury (OR, 1.00-1.04). Conclusion: The results indicate that shoulder strength and kinematic characteristics are not risk factors for shoulder injury in the Special Forces population. These findings are in opposition to the general findings of previous research using a retrospective analysis.

19.
Int J Sport Nutr Exerc Metab ; 29(3): 315-321, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30160550

RESUMO

Special operation forces participating in mountain warfare/cold weather (MWCW) training have higher energy demands, but adequate fueling is difficult to achieve. The purpose of the study was to determine energy expenditure relative to energy intake and examine fueling patterns during 3 days of MWCW training in Naval Special Warfare Sea, Air, Land (SEAL) Qualification Training (SQT) students. Ten SQT students (age: 23.3 ± 1.8 years, height: 182.3 ± 6.4 cm, and weight: 83.6 ± 4.5 kg) were fitted for heart rate and accelerometer monitors during MWCW training. Total daily energy expenditure was determined using a combination of direct observation and heart rate-VO2 regression. Total daily energy intake was collected using the Automated Self-Administered 24 (ASA24) assessment tool. Total daily energy expenditure for river crossing, alpine skills, and mountain patrol were 3,913 ± 293, 4,207 ± 400, and 5,457 ± 828 kcals, respectively. Reported total daily energy intakes were 2,854 ± 657 (river crossing) and 2,289 ± 680 kcals (mountain patrol), producing 1,044 ± 784 and 3,112 ± 1,420 kcal deficits, respectively. SQT students consumed 258 ± 95 g (3.1 ± 1.3 g·kg-1·day-1) of carbohydrates, 130 ± 55 g (1.6 ± 0.7 g·kg-1·day-1) of protein, and 113 ± 39 g (1.4 ± 0.5 g·kg-1·day-1) of fat. MWCW training evolutions elicited high total daily energy expenditure and inadequate energy intake, especially before and during active training sessions, which may lead to decreased work output, early onset fatigue, and increased risk of injury. Increasing total daily energy intake by providing fuel/fluids, primarily carbohydrates, during the planned breaks and "downtime" of each training evolution and focusing on provision of the balance of calories/macronutrients needed for a more complete and expedited recovery over dinner and evening snacks will help bridge the energy gap.


Assuntos
Temperatura Baixa , Ingestão de Energia , Metabolismo Energético , Condicionamento Físico Humano , Adulto , Carboidratos da Dieta/administração & dosagem , Frequência Cardíaca , Humanos , Masculino , Militares , Necessidades Nutricionais , Estudantes , Adulto Jovem
20.
J Sci Med Sport ; 22(4): 494-499, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30448087

RESUMO

Optimizing tactical fitness is important for combat readiness and injury prevention, especially as women have entered ground combat military occupational specialties. OBJECTIVES: To assess characteristics of male and female Marines by Combat Fitness Test (CFT) performance clusters. DESIGN: Cross-sectional study. METHODS: Anthropometric, body composition (BF%, fat and fat-free mass [FM and FFM], and Fight load index [FLI], physiological (maximal oxygen uptake, lactate threshold and anaerobic power/capacity), and musculoskeletal (isokinetic strength of the knee, shoulder, torso, and isometric strength of the ankle) assessments were obtained from 294 male (M) and female (F) Marines. Hierarchical cluster analysis classified Marines based on performance of two CFT events (sec): Maneuver Under Fire (MANUF) and Movement to Contact (MTC). Following tests for normality, one-way ANOVA or Kruskal Wallis tests, followed by Bonferroni post-hoc tests, assessed characteristics across clusters and sex (alpha=0.05). RESULTS: Two clusters (C) were determined: C1: N=66F, 16M and C2: N=18F, 194M, with C2 demonstrating better performance on the MANUF and MTC. C1F demonstrated significantly greater BF% and FLI than C1M, C2F, and C2M. C2M demonstrated significantly greater knee flexion strength than C1F and C2F, but C1M was only significantly greater than C1F. C2M demonstrated significantly greater ankle eversion and inversion strength than C1F. CONCLUSIONS: Women with increased BF%, increased FM and reduced FFM relative to a fighting load may have decreased performance in combat-related tasks. Training programs based on an individual Marine's baseline body composition and fitness characteristics can enhance combat fitness and force readiness.


Assuntos
Composição Corporal , Teste de Esforço , Militares , Aptidão Física , Estudos Transversais , Feminino , Humanos , Ácido Láctico/sangue , Masculino , Força Muscular , Consumo de Oxigênio , Adulto Jovem
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