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1.
Sports Biomech ; 21(6): 761-772, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31711366

RESUMO

Shoulder and elbow injuries among baseball pitchers of various ages and abilities continue to rise despite exhaustive efforts analysing pitch type and count; however, it has yet been determined if footwear plays a role in altering pitching mechanics and subsequently injury susceptibility. Therefore, the purpose of the study was to investigate the effect footwear might have on youth baseball pitching mechanics. Data were collected on eleven youth baseball pitchers wearing two different shoes on two different surface inclinations. A repeated measures ANOVA was utilised to determine differences between upper and lower extremity joint kinematics and kinetics (p < 0.05). Results indicate wearing moulded cleats elicited significantly greater amounts of shoulder internal rotation torque, angle and velocity as well as elbow varus torque. Turf shoes caused an increased plantarflexion joint angle in the stride leg ankle and shoulder external rotation torque, angle and velocity. The findings of this study suggest that the footwear worn by a youth baseball pitcher does alter the shoulder and elbow dynamics in the dominant throwing arm as well as the amount of ankle plantarflexion in the stride leg.


Assuntos
Beisebol , Articulação do Cotovelo , Articulação do Ombro , Adolescente , Beisebol/lesões , Fenômenos Biomecânicos , Cotovelo , Humanos , Sapatos
2.
Artigo em Inglês | MEDLINE | ID: mdl-34639811

RESUMO

BACKGROUND: Postural strategies such as ankle, hip, or combined ankle-hip strategies are used to maintain optimal postural stability, which can be influenced by the footwear type and physiological workload. PURPOSE: This paper reports previously unreported postural strategy scores during the six conditions of the sensory organization test (SOT). METHODS: Fourteen healthy males (age: 23.6 ± 1.2 years; height: 181 ± 5.3 cm; mass: 89.2 ± 14.6 kg) were tested for postural strategy adopted during SOT in three types of occupational footwear (steel-toed work boot, tactical work boot, low-top work shoe) every 30 min during a 4-h simulated occupational workload. Postural strategy scores were analyzed using repeated measures analysis of variance at 0.05 alpha level. RESULTS: Significant differences among postural strategy scores were only evident between SOT conditions, and but not between footwear type or the workload. CONCLUSIONS: Findings indicate that occupational footwear and occupational workload did not cause a significant change in reliance on postural strategies. The significant changes in postural strategy scores were due to the availability of accurate and/or conflicting sensory feedback during SOT conditions. In SOT conditions where all three types of sensory feedback was available, the ankle strategy was predominantly adopted, while more reliance on hip strategy occurred in conditions with absent or conflicting sensory feedback.


Assuntos
Equilíbrio Postural , Carga de Trabalho , Adulto , Articulação do Tornozelo , Retroalimentação Sensorial , Humanos , Masculino , Sapatos , Adulto Jovem
3.
Int J Exerc Sci ; 14(1): 462-472, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34055142

RESUMO

The vertical jump has been shown to be an effective tool in assessing neuromuscular fatigue. The two most common iterations of the vertical jump are the countermovement and squat jumps. This investigation sought to identify if differences exist between the two jumping strategies with regard to electromyography (EMG) and kinetics in a group of recreationally trained males. Twenty-two participants completed one experimental session, where three countermovement (CMJ) and three squat jumps (SJ) were performed using a counterbalanced within-subject design. Jump performance was evaluated with data obtained using a force platform. Additionally, EMG was collected on the vastus lateralis (VL), vastus medialis (VM), semitendinosus (ST) and medial gastrocnemius (MG). Greater EMG values were seen in the CMJ for ST as well as percentage of activation in the MG (p < 0.05). Increased values of mean force and mean power were observed in the SJ, while the CMJ showed greater peak and mean velocity. Greater jump heights in the CMJ were present as well (p < 0.05). These findings suggest that the increase in CMJ jump height due to the increase in propulsive velocity is not due to increases in knee extensors muscle activation.

4.
Artigo em Inglês | MEDLINE | ID: mdl-33562784

RESUMO

Muscle activity from the slipping leg have been previously used to analyze slip induced falls. However, the impact of casual alternative footwear on slipping leg muscle activity when exposed to slippery environments is still unknown. The purpose of the study was to analyze the impact of alternative footwear (crocs (CC) and flip-flops (FF)) compared to slip-resistant footwear (LT) on lower extremity muscle activity when exposed to dry gait (NG), unexpected (US), alert (AS), and expected slips (ES). Eighteen healthy males (age: 22.3 ± 2.2 years; height: 177.7 ± 6.9 cm; weight: 79.3 ± 7.6 kg) completed the study in a repeated measures design in three footwear sessions separated by 48 h. Electromyography (EMG) muscle activity from four muscles of the lead/slipping leg was measured during the stance phase of the gait-slip trials. A 3 (footwear) × 4 (gait-slip trials) repeated measures analysis of variance was used to analyze EMG dependent variables mean, peak, and percent of maximal voluntary contraction. Greater lower extremity muscle activation during the stance phase was seen in US and AS conditions compared to NG and ES. In addition, footwear differences were seen for the alternative footwear (CC and FF) during US and AS, while the low top slip resistant shoe had no differences across all gait trials, suggesting it as the most efficient footwear of choice, especially when maneuvering slippery flooring conditions, either with or without the knowledge of an impending slip.


Assuntos
Sapatos , Caminhada , Acidentes por Quedas , Fenômenos Biomecânicos , Marcha , Extremidade Inferior , Masculino
5.
Int J Exerc Sci ; 13(4): 826-836, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32922636

RESUMO

The vertical jump is commonly used as a means of evaluating athlete readiness. Athletes have been shown to arrive to training and competition in a hypohydrated state. Thus, this investigation sought to examine the impact of hydration status on both countermovement (CMJ) and squat jump (SJ) performance. Twenty-five recreationally trained males completed three CMJ and SJ in a euhydrated, hypohydrated and control condition. Conditions were separated by a minimum of 24 hours. Hydration status was assessed using urine specific gravity. Jump performance was evaluated using both kinematic and kinetic data obtained from a force platform. A repeated-measures ANOVA was performed for each variable of interest in both the CMJ and SJ. CMJ peak and mean force values were significantly greater in the euhydrated condition compared to the hypohydrated condition (p < 0.05), with no differences between the control condition and either experimental condition. SJ showed reductions in jump height, peak and mean velocity, peak and mean power and impulse from control and euhydrated conditions (p < 0.05). The findings of this investigation show that when performing jump testing, specifically SJ, that hydration status of the individual may impact commonly used variables to assess the readiness of the individual for a given day.

6.
Saf Health Work ; 10(3): 321-326, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31497328

RESUMO

BACKGROUND: Performing cognitive tasks and muscular fatigue have been shown to increase muscle activity of the lower extremity during quiet standing. A common intervention to reduce muscular fatigue is to provide a softer shoe-surface interface. However, little is known regarding how muscle activity is affected by softer shoe-surface interfaces during static standing. The purpose of this study was to assess lower extremity muscular activity during erect standing on three different standing surfaces, before and after an acute workload and during cognitive tasks. METHODS: Surface electromyography was collected on ankle dorsiflexors and plantarflexors, and knee flexors and extensors of fifteen male participants. Dependent electromyography variables of mean, peak, root mean square, and cocontraction index were calculated and analyzed with a 2 × 2 × 3 within-subject repeated measures analysis of variance. RESULTS: Pre-workload muscle activity did not differ between surfaces and cognitive task conditions. However, greater muscle activity during post-workload balance assessment was found, specifically during the cognitive task. Cognitive task errors did not differ between surface and workload. CONCLUSIONS: The cognitive task after workload increased lower extremity muscular activity compared to quite standing, irrespective of the surface condition, suggesting an increased demand was placed on the postural control system as the result of both fatigue and cognitive task.

7.
J Strength Cond Res ; 33(5): 1347-1353, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-29019867

RESUMO

Williams, CC, Gdovin, JR, Wilson, SJ, Cazas-Moreno, VL, Eason, JD, Hoke, EL, Allen, CR, Wade, C, and Garner, JC. The effects of various weighted implements on baseball swing kinematics in collegiate baseball players. J Strength Cond Res 33(5): 1347-1353, 2019-The purpose of this study was to investigate the effects of different warm-up (WU) devices on bat swing parameters including maximal resultant velocity (MRV), resultant velocity at ball contact (RVBC), time difference between MRV and RVBC, bat angle at MRV, bat angle at RVBC, and perceptual differences of each WU implement used by National Collegiate Athletic Association Division-I baseball players. Fifteen varsity baseball players completed 1 experimental session during fall training. Retroreflective markers were placed on the bat and tee to measure basic bat kinematics during the swing. Participants completed a general calisthenics WU before being counter-balanced into 1 of 4 WU conditions: standard bat (SB) (33 in/30 oz), fungo (10.6 oz), weighted gloves with SB (weighted gloves) (55.6 oz) and donut with SB (donut) (55.6 oz). Each participant was asked to perform their normal on-deck routine over a 2-minute period, finishing with 5 practice swings with the designated condition. After completion of the WU, a 1-minute rest period (simulating normal game conditions) was given to allow each participant to get set to perform 5 maximal swings with a SB. Five, 1 × 4 (group × condition) repeated measures analysis of variance examined the aforementioned variables. There were no significant differences in MRV, RVBC, time difference between MRV and RVBC, and bat angle at MRV and RVBC between all WU conditions. If presented with the current options, athletes should choose the WU implement with which they are most comfortable using before an at-bat situation.


Assuntos
Beisebol/fisiologia , Equipamentos Esportivos/normas , Universidades , Exercício de Aquecimento/fisiologia , Adolescente , Atletas , Fenômenos Biomecânicos , Humanos , Masculino , Descanso/fisiologia , Adulto Jovem
8.
Ergonomics ; 62(1): 103-114, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30196761

RESUMO

Postural stability has been shown to be impacted by footwear and task performed. This study analysed the impact of two military footwear, standard boot (STB) and minimalist boot (MTB) on postural stability, before (PRE) and after (POST) a load carriage task. Sixteen participants were tested for postural stability using sensory organisation and motor control tests on Neurocom Equitest™. Postural sway, equilibrium scores and postural latencies were analysed using a two-factor repeated measures ANOVA: boot type (STB-MTB) × time (PRE-POST) load carriage task. Significantly greater postural sway variables, lower balance scores and slower postural latencies were seen in STB and POST load carriage conditions (p < .05). The results suggest that MTB exhibited greater balance compared to STB in balance conditions that rely on somatosensory feedback and that balance is lowered after a load carriage task. Decrements in postural stability could be attributed to boot design characteristics and muscular exertion due to the load carriage task. Practitioner Summary: Maintaining optimal postural stability is crucial in military. Impact of military footwear types and load carriage task on postural stability are addressed. Findings provide footwear design and physical exertion implications on postural stability leading to potential interventions that reduce postural stability decrements; thereby, reducing potential falls and fall related injuries.


Assuntos
Militares , Equilíbrio Postural/fisiologia , Sapatos/efeitos adversos , Suporte de Carga/fisiologia , Carga de Trabalho , Acidentes por Quedas/prevenção & controle , Adulto , Ergonomia , Feminino , Humanos , Masculino , Traumatismos Ocupacionais/etiologia , Traumatismos Ocupacionais/prevenção & controle , Adulto Jovem
9.
J Strength Cond Res ; 32(1): 237-243, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28777246

RESUMO

Allen, CR, Fu, Y-C, Cazas-Moreno, V, Valliant, MW, Gdovin, JR, Williams, CC, and Garner, JC. Effects of jaw clenching and jaw alignment mouthpiece use on force production during vertical jump and isometric clean pull. J Strength Cond Res 32(1): 237-243, 2018-This study examined the effects of jaw clenching, a self-adapted, jaw-repositioning mouthpiece on force production during maximum countermovement vertical jump and maximum isometric midthigh clean pull assessments in an attempt to determine any ergogenic effect attributable to clenching, jaw-repositioning mouthpiece use, or the combination of both. Thirty-six male subjects performed vertical jump and isometric clean pull assessments from a force platform under various mouthpiece and clench conditions. A 3 × 2 (mouthpiece × clench) repeated-measures analysis of variance was conducted to analyze each of the following force production variables for both assessments: peak force, normalized peak force, and rate of force development. In addition, jump height was analyzed for the vertical jump. Results revealed improvements in peak force (F1,35 = 15.84, p ≤ 0.001, (Equation is included in full-text article.)= 0.31), normalized peak force (F1,35 = 16.28, p ≤ 0.001, (Equation is included in full-text article.)= 0.32), and rate of force development (F1,35 = 12.89, p = 0.001, (Equation is included in full-text article.)= 0.27) during the isometric clean pull assessment when participants maximally clenched their jaw, regardless of mouthpiece condition. There were no statistically significant differences in jump height, peak force, normalized peak force, or rate of force development during the vertical jump for any treatment condition. This study supports previous research demonstrating that the implementation of remote voluntary contractions such as jaw clenching can lead to concurrent activation potentiation and a resulting ergogenic effect during activities involving and requiring high-force production.


Assuntos
Contração Isométrica/fisiologia , Arcada Osseodentária/fisiologia , Protetores Bucais , Força Muscular/fisiologia , Coxa da Perna/fisiologia , Adolescente , Adulto , Humanos , Masculino , Músculo Esquelético/fisiologia , Adulto Jovem
10.
J Mot Behav ; 50(5): 590-597, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29058537

RESUMO

The use of vibrating platforms has become increasingly available, and popular at sports and rehabilitation institutes. Given the discrepancies in the literature regarding whole body vibration (WBV) and human reflexive responses, the purpose of this study was to examine the acute effects of WBV on postural response latencies, as well as associated electromyography measures of the lower extremities during balance perturbations. Reflexive responses during backward and forward balance perturbations were examined before, after, and 10 min after a bout of WBV. The findings suggest that following an acute bout of whole body vibration, muscle activity of the lower extremities is decreased during a reflexive response to an unexpected perturbation, and may be associated with faster reaction time.


Assuntos
Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Equilíbrio Postural/fisiologia , Vibração , Eletromiografia , Feminino , Humanos , Masculino , Adulto Jovem
11.
Int J Health Sci (Qassim) ; 11(4): 8-12, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29085261

RESUMO

OBJECTIVE: Given that females exhibit a greater prevalence of eating disorders, there is of yet no conclusive evidence whether participation in college athletics exacerbates eating disorders or body shape dissatisfaction. This study assessed how gender and participation in collegiate athletics are associated with increased risk for disordered eating attitudes and body shape concerns in college students. METHODS: This study used a cross-sectional research design. A total of 302 students at a Southern US university fully completed the eating attitudes test and the body shape questionnaire during class time or team meetings. Logistic regression was conducted to determine risk differentials for each group. RESULTS: Of 302 students, 65.6% were females and 63.2% were non-athletes. Athletic status was significant as well but became slightly less so with adjustment (unadjusted at OR = 3.14, P < 0.001 vs. adjusted OR = 3.22, P < 0.001). Moreover, it was found that that non-athletic female students are slightly more at risk for disordered eating and significantly more dissatisfied with their body shape (OR = 5.95, P < 0.001). CONCLUSIONS: Although there seems to still be many unresolved issues regarding eating disorders, one thing is clear females are at higher risk, and it remains a significant challenge to college health services. College health practitioners should be made aware of the significant effect stress has on freshman in particular.

12.
Int J Exerc Sci ; 10(5): 782-797, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28966715

RESUMO

Prior work has reported that the declines observed in body mass index (BMI) and circumference measurements in their cross-sectional data were twice as large when calculated from distance energy expenditure estimations compared to energy expenditure estimations based on time and intensity. The primary purpose of this study was to compare walking/running for distance to walking/running for time as part of an exercise intervention. This study followed a between-subjects, repeated measures design. Fifteen overweight, but otherwise healthy participants completed the study. The time-based group walked/ran for self-reported time while the distance-based group walked/ran for self-reported distance. A mixed-factor repeated-measures ANOVA was used to compare all dependent variables both within-subjects and between-subjects. Weekly adherence rates to the exercise program did not exhibit a significant difference (p > 0.05). Significant interactions were shown for mean body mass loss between groups as well as mean blood glucose level (p < 0.05). Distance-based group exhibited a decline in body mass and blood glucose while the time-based group exhibited an increase in both variables. To the best of the authors' knowledge, the present study is the first to directly compare a distance-based vs. a time-based exercise program for walking and running for improvement of risk factors of cardiovascular disease. The results of this study would suggest that a distance-based exercise prescription of walking or running should provide a clinician or researcher with a closer estimation of overall accumulated exercise and resultant weight loss.

13.
Int J Occup Saf Ergon ; 23(4): 558-569, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27858517

RESUMO

Slips occur as a result of failure of normal locomotion. The purpose of this study is to analyze the impact of alternative footwear (Crocs™, flip-flops) and an industry standard low-top slip-resistant shoe (SRS) under multiple gait trials (normal dry, unexpected slip, alert slip and expected slip) on lower extremity joint kinematics, kinetics and muscle activity. Eighteen healthy male participants (age: 22.28 ± 2.2 years; height: 177.66 ± 6.9 cm; mass: 79.27 ± 7.6 kg) completed the study. Kinematic, kinetic and muscle activity variables were analyzed using a 3(footwear) × 4(gait trials) repeated-measures analysis of variance at p = 0.05. Greater plantar flexion angles, lower ground reaction forces and greater muscle activity were seen on slip trials with the alternative footwear. During slip events, SRS closely resembled normal dry biomechanics, suggesting it to be a safer footwear choice compared with alternative footwear.


Assuntos
Marcha/fisiologia , Sapatos , Caminhada/fisiologia , Acidentes por Quedas/prevenção & controle , Adulto , Fenômenos Biomecânicos , Humanos , Extremidade Inferior/fisiologia , Masculino
14.
J Electromyogr Kinesiol ; 30: 119-25, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27371905

RESUMO

Determining muscle contractile properties following exercise is critical in understanding neuromuscular function. Following high intensity training, individuals often experience exercise induced muscle damage (EIMD). The purpose of this investigation was to determine the effect of whole-body vibration (WBV) on muscle contractile properties following EIMD. Twenty-seven females volunteered for 7 sessions and were randomly assigned to a treatment or control group. Muscle contractile properties were assessed via voluntary torque (VT), peak twitch torque (TT), time to reach peak torque, half relaxation time of twitch torque, percent activation (%ACT), rate of rise (RR), rate of decline (RD), mean and peak electromyography during maximum voluntary isometric contraction. Two testing sets were collected each day, consisting of pre measures followed by WBV or control and post measures. A mixed factor analysis of variance was conducted for each variable. %ACT measures found baseline being less than day 1 in both measures in the control group. TT was found to be greater in the control group compared to WBV group. TT and VT baseline measures were greater than all other time points. RR showed control group had higher values than WBV group. These results indicate that WBV following EIMD had some positive effects on muscle contractile properties.


Assuntos
Exercício Físico/fisiologia , Contração Isométrica/fisiologia , Músculo Esquelético/lesões , Músculo Esquelético/fisiologia , Vibração , Eletromiografia/métodos , Feminino , Humanos , Modalidades de Fisioterapia/efeitos adversos , Torque , Resultado do Tratamento , Vibração/efeitos adversos , Vibração/uso terapêutico , Adulto Jovem
15.
Prev Med ; 87: 41-46, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26896633

RESUMO

OBJECTIVE: Studies have looked at the individual associations of sensory impairment on balance, but no population-based studies have examined their combined association on balance and difficulty with falls. Thus, the purpose of this study was to examine both the independent associations and combined associations of visual impairment, peripheral neuropathy, and self-reported hearing loss with the odds of reporting difficulty with falls and functional balance. METHODS: Data from the 2003-2004 National Health and Nutrition Examination Survey were used. Vision and peripheral neuropathy were objectively measured, and hearing was self-reported. Balance testing consisted of a modified Romberg test. After exclusions, 1662 (40-85years of age) participants provided complete data on the study variables. RESULTS: Sensory impairment was associated with perceived difficulty of falls and functional balance. Participants who presented a single sensory impairment had 29% reduced odds of having functional balance (95% CI=0.54-0.93, p=0.01) and increased odds of reporting difficulty with falls by 61% (95% CI=0.99-2.60, p=0.05). Moreover, our multisensory models showed some evidence of a dose-response relationship, in that sensory impairment of multiple sensory systems was associated with worse balance (OR =0.59, CI=0.35-1.00, p=0.05) and perceived difficulty of falls (OR =5.02, 95% CI=1.99-12.66, p=0.002) when compared to those with less sensory impairment. CONCLUSION: Multiple sensory impairment is associated with significantly higher odds of both reporting difficulty with falls and balance dysfunction, which may lead to a subsequent fall, ultimately compromising the individual's health.


Assuntos
Acidentes por Quedas/estatística & dados numéricos , Perda Auditiva , Doenças do Sistema Nervoso Periférico , Equilíbrio Postural/fisiologia , Transtornos da Visão , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos Nutricionais , Autorrelato , Estados Unidos
16.
J Res Health Sci ; 16(4): 228-232, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28087857

RESUMO

BACKGROUND: Osteoporosis is a systemic skeletal disorder characterized by low bone mineral density (BMD) that leads to an increase in bone fragility, causing an individual to be at an increased risk for fractures. Asian-Indians are at an increased risk for developing osteoporosis. Considering the number of Asian-Indians in the US is rapidly growing, they likely could be an underappreciated population at risk for bone fractures. The aim of this study was to investigate bone health and determine the factors affecting BMD in Asian-Indians living in the US. METHODS: Asian-Indians residing in Northern Mississippi (n = 87) were enrolled in this cross-sectional study from June 2013 to August 2014. Eligible participants completed a self-administered Osteoporosis Risk Factor Assessment questionnaire. BMD and body composition were measured using a dual energy x-ray absorptiometry scan (DXA). RESULTS: Eight-seven Asian-Indians (male: 62.1%) participated, with the average age being 28.49 yr old (SD = 6.62). Overall, 31.0% and 48.3% had low femoral neck BMD and spinal BMD, respectively. Multiple regression analysis revealed that age, percent body fat, and body mass index (BMI) significantly predicted BMD at femur neck (P<0.05). Additionally, percent body fat, BMI, childhood milk consumption, and gender were statistically significant predictors of spinal BMD (P<0.05). CONCLUSIONS: The findings from this study should be beneficial to healthcare providers that work with Asian-Indian population groups. Health promotion programs focusing on osteoporosis prevention are needed among Asian-Indians to prevent the risk of fractures.


Assuntos
Tecido Adiposo/metabolismo , Povo Asiático , Composição Corporal , Índice de Massa Corporal , Densidade Óssea , Osso e Ossos/metabolismo , Osteoporose , Adolescente , Adulto , Animais , Criança , Estudos Transversais , Comportamento Alimentar , Feminino , Colo do Fêmur/metabolismo , Humanos , Índia/etnologia , Masculino , Pessoa de Meia-Idade , Leite , Mississippi/epidemiologia , Osteoporose/etnologia , Osteoporose/etiologia , Projetos Piloto , Coluna Vertebral/metabolismo , Adulto Jovem
17.
J Strength Cond Res ; 28(2): 499-503, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24263660

RESUMO

Because of the relative newness of mouthpieces, there are few investigations into using performance mouthpieces during sport and physical activity to substantiate claims of performance enhancement. The purpose of this study was to investigate the acute effect of a commercially available, noninjury preventive, performance mouthpiece on practical acute performance measures of power and strength. A within-subjects design was used to evaluate 21 (N = 21) recreationally trained college aged males on the performance of a maximum countermovement vertical jump (CMVJ) from a force platform and 1 repetition maximum (1RM) bench press exercise for the following conditions: with mouthpiece (MP) and without mouthpiece (noMP). Rate of force development (RFD) and peak vertical force (PF) were derived from force platform data. Statistical analysis revealed no significant differences between conditions for CMVJ height (p = 0.13), RFD at 200 ms (p = 0.09), PF (p = 0.08), and 1RM bench press (p = 0.45). These data indicate that the use of this particular jaw aligning mouthpiece specifically in an attempt to produce an ergogenic effect on performance is unwarranted.


Assuntos
Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Placas Oclusais , Condicionamento Físico Humano/fisiologia , Treinamento Resistido , Adolescente , Teste de Esforço , Humanos , Masculino , Movimento/fisiologia , Adulto Jovem
18.
Ergonomics ; 57(1): 66-73, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24354716

RESUMO

Railroad workers often perform daily work activities on irregular surfaces, specifically on ballast rock. Previous research and injury epidemiology have suggested a relationship between working on irregular surfaces and postural instability. The purpose of this study was to examine the impact of walking on ballast for an extended duration on standing balance. A total of 16 healthy adult males walked on a 7.62 m × 4.57 m (25 ft × 15 ft) walking surface of no ballast (NB) or covered with ballast (B) of an average rock size of about 1 inch for 4 h. Balance was evaluated using dynamic posturography with the NeuroCom(®) Equitest System(™) prior to experiencing the NB or B surface and again every 30 min during the 4 h of ballast exposure. Dependent variables were the sway velocity and root-mean-square (RMS) sway components in the medial-lateral and anterior-posterior directions. Repeated measures ANOVA revealed statistically significant differences in RMS and sway velocity between ballast surface conditions and across exposure times. Overall, the ballast surface condition induced greater sway in all of the dynamic posturography conditions. Walking on irregular surfaces for extended durations has a deleterious effect on balance compared to walking on a surface without ballast. These findings of changes in balance during ballast exposure suggest that working on an irregular surface may impact postural control.


Assuntos
Equilíbrio Postural/fisiologia , Ferrovias , Caminhada/fisiologia , Adolescente , Adulto , Análise de Variância , Fenômenos Biomecânicos , Marcha/fisiologia , Humanos , Masculino , Saúde Ocupacional , Propriedades de Superfície , Fatores de Tempo , Adulto Jovem
19.
J Strength Cond Res ; 26(2): 422-31, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22240547

RESUMO

Complex training (CT; alternating between heavy and lighter load resistance exercises with similar movement patterns within an exercise session) is a form of training that may potentially bring about a state of postactivation potentiation, resulting in increased dynamic power (Pmax) and rate of force development during the lighter load exercise. Such a method may be more effective than either modality, independently for developing strength. The purpose of this research was to compare the effects of resistance training (RT), plyometric training (PT), and CT on lower body strength and anthropometrics. Thirty recreationally trained college-aged men were trained using 1 of 3 methods: resistance, plyometric, or complex twice weekly for 6 weeks. The participants were tested pre, mid, and post to assess back squat strength, Romanian dead lift (RDL) strength, standing calf raise (SCR) strength, quadriceps girth, triceps surae girth, body mass, and body fat percentage. Diet was not controlled during this study. Statistical measures revealed a significant increase for squat strength (p = 0.000), RDL strength (p = 0.000), and SCR strength (p = 0.000) for all groups pre to post, with no differences between groups. There was also a main effect for time for girth measures of the quadriceps muscle group (p = 0.001), the triceps surae muscle group (p = 0.001), and body mass (p = 0.001; post hoc revealed no significant difference). There were main effects for time and group × time interactions for fat-free mass % (RT: p = 0.031; PT: p = 0.000). The results suggest that CT mirrors benefits seen with traditional RT or PT. Moreover, CT revealed no decrement in strength and anthropometric values and appears to be a viable training modality.


Assuntos
Força Muscular , Músculo Esquelético/fisiologia , Educação Física e Treinamento/métodos , Exercício Pliométrico , Treinamento Resistido/métodos , Adiposidade , Adolescente , Adulto , Análise de Variância , Peso Corporal , Humanos , Extremidade Inferior/fisiologia , Masculino , Músculo Quadríceps/anatomia & histologia , Extremidade Superior/fisiologia , Adulto Jovem
20.
J Strength Cond Res ; 25(11): 3191-7, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21993031

RESUMO

The purpose of this study was to examine changes in physical activity and fitness variables in members of 8 volunteer families after 3 months of home use of the Wii Fit™ interactive video game. Pre and postintervention measurements were obtained from 21 subjects relative to physical activity (5 days of accelerometry), aerobic fitness (graded treadmill test), muscular fitness (push-ups), flexibility (sit-and-reach test), balance (composite equilibrium score), and body composition (body mass index and % body fat). Use characteristics of the Wii Fit™ device were also determined. A series of 2 (age group) × 2 (time) repeated measures analyses of variance were conducted to assess changes over time and between adults and children. Three months of home Wii Fit™ use revealed no significant age group × time interactions or main effects of group or time for daily physical activity, muscular fitness, flexibility, balance, or body composition. An age group × time interaction (p = 0.04) was observed in peak VO2 (ml·kg(-1)·min(-1)) with children displaying a significant (p = 0.03) increase after 3 months of Wii Fit™ use, whereas adults showed no significant (p = 0.50) change. Daily Wii Fit™ use per household declined by 82% (p < 0.01) from 21.5 ± 9.0 min·d(-1) during the first 6 weeks to 3.9 ± 4.0 min·d(-1) during the second 6 weeks. Most measures of health-related fitness in this exploratory study remained unchanged after 3 months of home use of the popular Wii Fit™ whole-body movement interactive video game. Modest daily Wii Fit™ use may have provided insufficient stimulus for fitness changes.


Assuntos
Atividade Motora/fisiologia , Aptidão Física/fisiologia , Jogos de Vídeo , Adolescente , Adulto , Composição Corporal/fisiologia , Índice de Massa Corporal , Criança , Teste de Esforço , Feminino , Humanos , Masculino , Músculo Esquelético/fisiologia , Consumo de Oxigênio/fisiologia , Equilíbrio Postural/fisiologia , Amplitude de Movimento Articular/fisiologia
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