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1.
J Occup Health Psychol ; 29(3): 155-173, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38913703

RESUMO

Childhood adversity stains the past of millions of working adults worldwide. The impact on health and well-being is substantial-a now-acknowledged public health crisis. Yet, research in the organizational sciences has failed to recognize the burden that individuals with this difficult history carry with them into the workforce. By synthesizing an interdisciplinary body of scholarship into a cohesive theoretical framework, we provide a foundation for emerging work in occupational health psychology. Empirically, across two single-level multiwave studies, we demonstrate the importance of adversity in one's childhood and its impact on the workplace specifically showing that child adversity, directly and indirectly, impacts worker attitudes and discretionary behaviors. Further, providing one of the few examinations of stress proliferation theory in the workplace, we demonstrate adulthood adversity as an essential mediating mechanism that leads to these work outcomes. From an applied perspective, our results highlight a need to focus on the healing and recovery of adult survivors as they work toward breaking the chains of the past in their lives and at work. In presenting this life course perspective on organizational attitudes and behaviors, our work offers a unique and vital contribution to occupational health theory, practice, and research. (PsycInfo Database Record (c) 2024 APA, all rights reserved).


Assuntos
Atitude , Humanos , Adulto , Feminino , Masculino , Local de Trabalho/psicologia , Pessoa de Meia-Idade , Cultura Organizacional , Criança , Experiências Adversas da Infância , Estresse Psicológico/psicologia , Estresse Ocupacional/psicologia
2.
Psychol Rep ; : 332941241239267, 2024 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-38485653

RESUMO

Despite financial concerns representing of the most substantial sources of stress, the intersection between individual differences and financial stress has received sparce attention. Emphasizing the cognitive-appraisal process, our study reveals financial stress perceptions partly reflect a dispositional tendency to interpret financial information either more positively or negatively. Across two studies (N = 441; N = 348), we found that positive and negative affect predict subjective financial perceptions of income adequacy. Further, using Relative Weights Analysis, we demonstrate that in predicting financial stress perceptions, dispositional affect is as important as, or more important than, objective measures of financial stress (i.e., household income and debt). Lastly, using moderated mediation, we found that both current and future perceived income adequacy mediate the relationship between one's income and their experience of affective financial strain, and dispositional affect moderates this relationship. Our work informs current research and interventions seeking to understand individual differences in financial stress perceptions.

3.
J Electr Bioimpedance ; 13(1): 10-20, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35646197

RESUMO

This study evaluated the influence of acute water ingestion and maintaining an upright posture on raw bioimpedance and subsequent estimates of body fluids and composition. Twenty healthy adults participated in a randomized crossover study. In both conditions, an overnight food and fluid fast was followed by an initial multi-frequency bioimpedance assessment (InBody 770). Participants then ingested 11 mL/kg of water (water condition) or did not (control condition) during a 5-minute period. Thereafter, bioimpedance assessments were performed every 10 minutes for one hour with participants remaining upright throughout. Linear mixed effects models were used to examine the influence of condition and time on raw bioimpedance, body fluids, and body composition. Water consumption increased impedance of the arms but not trunk or legs. However, drift in leg impedance was observed, with decreasing values over time in both conditions. No effects of condition on body fluids were detected, but total body water and intracellular water decreased by ~0.5 kg over time in both conditions. Correspondingly, lean body mass did not differ between conditions but decreased over the measurement duration. The increase in body mass in the water condition was detected exclusively as fat mass, with final fat mass values ~1.3 kg higher than baseline and also higher than the control condition. Acute water ingestion and prolonged standing exert practically meaningful effects on relevant bioimpedance variables quantified by a modern, vertical multi-frequency analyzer. These findings have implications for pre-assessment standardization, methodological reporting, and interpretation of assessments.

4.
J Strength Cond Res ; 36(11): 3093-3104, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34172636

RESUMO

ABSTRACT: Rodriguez, C, Harty, PS, Stratton, MT, Siedler, MR, Smith, RW, Johnson, BA, Dellinger, JR, Williams, AD, White, SJ, Benavides, ML, and Tinsley, GM. Comparison of indirect calorimetry and common prediction equations for evaluating changes in resting metabolic rate induced by resistance training and a hypercaloric diet. J Strength Cond Res 36(11): 3093-3104, 2022-The ability to accurately identify resting metabolic rate (RMR) changes over time allows practitioners to prescribe appropriate adjustments to nutritional intake. However, there is a lack of data concerning the longitudinal utility of commonly used RMR prediction equations. The purpose of this study was to evaluate the validity of several commonly used prediction equations to track RMR changes during a hypercaloric nutritional intervention and supervised resistance exercise training program. Twenty resistance-trained men completed the study. The protocol lasted 6 weeks, and subjects underwent RMR assessments by indirect calorimetry (IC) preintervention and postintervention to obtain reference values. Existing RMR prediction equations based on body mass (BM) or dual-energy X-ray absorptiometry fat-free mass (FFM) were also evaluated. Equivalence testing was used to evaluate whether each prediction equation demonstrated equivalence with IC. Null hypothesis significance testing was also performed, and Bland-Altman analysis was used alongside linear regression to assess the degree of proportional bias. Body mass and FFM increased by 3.6 ± 1.7 kg and 2.4 ± 1.6 kg, respectively. Indirect calorimetry RMR increased by 165 ± 97 kcal·d -1 , and RMR:FFM increased by 5.6 ± 5.2%. All prediction equations underestimated mean RMR changes relative to IC, with magnitudes ranging from 75 to 155 kcal·d -1 , while also displaying unacceptable levels of negative proportional bias. In addition, no equation demonstrated equivalence with IC. Common RMR prediction equations based on BM or FFM did not fully detect the increase in RMR observed with resistance training plus a hypercaloric diet. Overall, the evaluated prediction equations are unsuitable for estimating RMR changes in the context of this study.


Assuntos
Metabolismo Basal , Treinamento Resistido , Masculino , Humanos , Calorimetria Indireta/métodos , Absorciometria de Fóton , Dieta , Composição Corporal
5.
J Funct Morphol Kinesiol ; 6(2)2021 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-33919267

RESUMO

Relatively few investigations have reported purposeful overfeeding in resistance-trained adults. This preliminary study examined potential predictors of resistance training (RT) adaptations during a period of purposeful overfeeding and RT. Resistance-trained males (n = 28; n = 21 completers) were assigned to 6 weeks of supervised RT and daily consumption of a high-calorie protein/carbohydrate supplement with a target body mass (BM) gain of ≥0.45 kg·wk-1. At baseline and post-intervention, body composition was evaluated via 4-component (4C) model and ultrasonography. Additional assessments of resting metabolism and muscular performance were performed. Accelerometry and automated dietary interviews estimated physical activity levels and nutrient intake before and during the intervention. Bayesian regression methods were employed to examine potential predictors of changes in body composition, muscular performance, and metabolism. A simplified regression model with only rate of BM gain as a predictor was also developed. Increases in 4C whole-body fat-free mass (FFM; (mean ± SD) 4.8 ± 2.6%), muscle thickness (4.5 ± 5.9% for elbow flexors; 7.4 ± 8.4% for knee extensors), and muscular performance were observed in nearly all individuals. However, changes in outcome variables could generally not be predicted with precision. Bayes R2 values for the models ranged from 0.18 to 0.40, and other metrics also indicated relatively poor predictive performance. On average, a BM gain of ~0.55%/week corresponded with a body composition score ((∆FFM/∆BM)*100) of 100, indicative of all BM gained as FFM. However, meaningful variability around this estimate was observed. This study offers insight regarding the complex interactions between the RT stimulus, overfeeding, and putative predictors of RT adaptations.

6.
Eur J Clin Nutr ; 75(7): 1060-1068, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33727706

RESUMO

BACKGROUND: Due to inherent errors involved in the transformation of raw bioelectrical variables to body fluids or composition estimates, the sole use of resistance (R), reactance (Xc), and phase angle (φ) has been advocated when quantifying longitudinal changes. The aim of this investigation was to assess the ability of four bioimpedance analyzers to detect raw bioimpedance changes induced by purposeful weight gain with resistance training. METHODS: Twenty-one resistance trained males completed a 6-week lifestyle intervention with the aim of purposeful weight gain. Bioimpedance analysis was performed before and after the intervention using four different analyzers (MFBIAInBody: InBody 770; MFBIASECA: Seca mBCA 515/514; BIS: ImpediMed SFB7; SFBIA: RJL Quantum V) for the quantification of R, Xc, and φ at the 50-kHz frequency. Repeated measures ANOVA and follow up tests were performed. RESULTS: Analysis revealed main effects of time and method for R, Xc, and φ (p ≤ 0.02), without significant time x method interactions (p ≥ 0.07). Follow up for time main effects indicated that, on average, R decreased by 4.5-5.8%, Xc decreased by 2.3-4.0%, and φ increased by 1.8-2.6% across time for all analyzers combined. However, varying levels of disagreement in absolute values were observed for each bioelectrical variable. CONCLUSIONS: The differences in absolute bioelectrical values suggests that analyzers should not be used interchangeably, which holds particular importance when reference values are utilized. Despite absolute differences, analyzers with varying characteristics demonstrated similar abilities to detect changes in R, Xc, and φ over time.


Assuntos
Treinamento Resistido , Composição Corporal , Impedância Elétrica , Humanos , Masculino , Projetos de Pesquisa , Aumento de Peso
7.
Physiol Meas ; 42(3)2021 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-33592586

RESUMO

Objective. Bioimpedance devices are commonly used to assess health parameters and track changes in body composition. However, the cross-sectional agreement between different devices has not been conclusively established. Thus, the objective of this investigation was to examine the agreement between raw bioelectrical variables (resistance, reactance, and phase angle at the 50 kHz frequency) obtained from three bioimpedance analyzers.Approach. Healthy male (n = 76, mean ± SD; 33.8 ± 14.5 years; 83.9 ± 15.1 kg; 179.4 ± 6.9 cm) and female (n = 103, mean ± SD; 33.4 ± 15.9 years; 65.6 ± 12.1 kg; 164.9 ± 6.4 cm) participants completed assessments using three bioimpedance devices: supine bioimpedance spectroscopy (BIS), supine single-frequency bioelectrical impedance analysis (SFBIA), and standing multi-frequency bioelectrical impedance analysis (MFBIA). Differences in raw bioelectrical variables between the devices were quantified via one-way analysis of variance for the total sample and for each sex. Equivalence testing was used to determine equivalence between methods.Main results. Significant differences in all bioelectrical variables were observed between the three devices when examining the total sample and males only. The devices appeared to exhibit slightly better agreement when analyzing female participants only. Equivalence testing using the total sample as well as males and females separately revealed that resistance and phase angle were equivalent between the supine devices (BIS, SFBIA), but not with the standing analyzer (MFBIA).Significance. The present study demonstrated disagreement between different bioimpedance analyzers for quantifying raw bioelectrical variables, with the poorest agreement between devices that employed different body positions during testing. These results suggest that researchers and clinicians should employ device-specific reference values to classify participants based on raw bioelectrical variables, such as phase angle. If reference values are needed but are unavailable for a particular bioimpedance analyzer, the set of reference values produced using the most similar analyzer and reference population should be selected.


Assuntos
Composição Corporal , Estudos Transversais , Impedância Elétrica , Feminino , Humanos , Masculino , Análise Espectral
8.
Med Sci Sports Exerc ; 53(3): 658-667, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-32804903

RESUMO

PURPOSE: The purpose of this study was to assess the agreement between a field-based three-compartment (3CFIELD) model and a laboratory-based three-compartment (3CLAB) model for tracking body composition changes over time. METHODS: Resistance-trained males completed a supervised nutrition and resistance training intervention. Before and after the intervention, assessments were performed via air displacement plethysmography (ADP), bioimpedance spectroscopy (BIS), portable ultrasonography (US), and bioelectrical impedance analysis (BIA). ADP body density and BIS body water were used within the reference 3CLAB model, whereas US-derived body density and BIA body water were used within the 3CFIELD model. Two-compartment model body composition estimates provided by US and BIA were also examined. Changes in fat-free mass and fat mass were analyzed using repeated-measures ANOVA, equivalence testing, Bland-Altman analysis, linear regression, and related validity analyses. RESULTS: Significant increases in fat-free mass (3CLAB, 4.0 ± 4.5 kg; 3CFIELD, 3.9 ± 4.2 kg; US, 3.2 ± 4.3 kg; BIA, 3.9 ± 4.2 kg) and fat mass (3CLAB, 1.3 ± 2.2 kg; 3CFIELD, 1.4 ± 2.2 kg; US, 2.1 ± 2.6 kg; BIA, 1.4 ± 2.9 kg) were detected by all methods. However, only the 3CFIELD model demonstrated equivalence with the 3CLAB model. In addition, the 3CFIELD model exhibited superior performance to US and BIA individually, as indicated by the total error (3CFIELD, 1.0 kg; US, 1.8 kg; BIA, 1.6 kg), 95% limits of agreement (3CFIELD, ±2.1 kg; US, ±3.3 kg; BIA, ±3.1 kg), correlation coefficients (3CFIELD, 0.79-0.82; US, 0.49-0.55; BIA, 0.61-0.72), and additional metrics. CONCLUSIONS: The present study demonstrated the potential usefulness of a 3CFIELD model incorporating US and BIA data for tracking body composition changes over time, as well as its superiority to US or BIA individually. As such, this accessible multicompartment model may be suitable for implementation in field or limited-resource settings.


Assuntos
Tecido Adiposo/fisiologia , Composição Corporal/fisiologia , Treinamento Resistido , Tecido Adiposo/diagnóstico por imagem , Adulto , Análise de Variância , Água Corporal , Carboidratos da Dieta/administração & dosagem , Proteínas Alimentares/administração & dosagem , Impedância Elétrica , Humanos , Modelos Lineares , Masculino , Avaliação Nutricional , Pletismografia/métodos , Reprodutibilidade dos Testes , Fatores de Tempo , Ultrassonografia , Adulto Jovem
10.
J Int Soc Sports Nutr ; 17(1): 45, 2020 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-32831109

RESUMO

BACKGROUND: Energy drinks are often consumed by the general population, as well as by active individuals seeking to enhance exercise performance and augment training adaptations. However, limited information is available regarding the efficacy of these products. Thus, the purpose of this study was to determine the effects of a commercially available caffeine- and protein-containing energy drink on metabolism and muscular performance. METHODS: Sixteen resistance-trained males (n = 8; mean ± SD; age: 22.4 ± 4.9 years; body mass: 78.8 ± 14.0 kg; body fat: 15.3 ± 6.4%) and females (n = 8; age: 24.5 ± 4.8 years; body mass: 67.5 ± 11.9 kg; body fat: 26.6 ± 7.1%) participated in this randomized, double-blind, placebo-controlled, crossover study. Following a familiarization visit, participants completed two identical visits to the laboratory separated by 5-10 days, each of which consisted of indirect calorimetry energy expenditure (EE) assessments before and after consumption of the beverage (Bang® Keto Coffee; 130 kcal, 300 mg caffeine, 20 g protein) or placebo (30 kcal, 11 mg caffeine, 1 g protein) as well as after exercise testing. In addition, participants' subjective feelings of energy, fatigue, and focus as well as muscular performance (leg press one-repetition maximum and repetitions to fatigue, maximal isometric and isokinetic squat testing) were assessed. Multiple repeated measures ANOVAs with Tukey post-hoc tests were used to analyze data. Estimates of effect size were quantified via partial eta squared (ηP2) and Hedge's g. RESULTS: A significant interaction effect was identified for EE (p < 0.001, ηP2 = 0.52) but not respiratory exchange ratio (p = 0.17, ηP2 = 0.11). Following consumption of the beverage, EE was 0.18 [corrected] kcal·min- 1 greater than placebo at the post-beverage time point (p < 0.001) and 0.08 [corrected] kcal·min- 1 greater than placebo at the post-exercise time point (p = 0.011). However, no between-condition differences were detected for any subjective or muscular performance outcomes. CONCLUSIONS: The results of this study suggest that consumption of the energy drink had minimal effects on lower-body muscular performance and subjective factors in the context of a laboratory setting. However, the beverage was found to significantly increase energy expenditure compared to placebo immediately following ingestion as well as during the recovery period after an exercise bout, suggesting that active individuals may improve acute metabolic outcomes via consumption of a caffeine- and protein-containing energy drink. TRIAL REGISTRATION: This trial was prospectively registered at ClinicalTrials.gov (Identifier: NCT04180787 ; Registered 29 November 2019).


Assuntos
Café , Bebidas Energéticas , Metabolismo Energético/fisiologia , Exercício Físico/fisiologia , Músculo Esquelético/fisiologia , Treinamento Resistido , Adolescente , Adulto , Cafeína/farmacologia , Calorimetria Indireta , Estudos Cross-Over , Método Duplo-Cego , Metabolismo Energético/efeitos dos fármacos , Teste de Esforço/métodos , Feminino , Humanos , Perna (Membro)/fisiologia , Masculino , Músculo Esquelético/efeitos dos fármacos , Substâncias para Melhoria do Desempenho/farmacologia , Troca Gasosa Pulmonar/efeitos dos fármacos , Treinamento Resistido/métodos , Levantamento de Peso/fisiologia , Adulto Jovem
11.
J Acoust Soc Am ; 131(1): 608-19, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22280623

RESUMO

Chest percussion is a traditional technique used for the physical examination of pulmonary injuries and diseases. It is a method of tapping body parts with fingers or small instruments to evaluate the size, consistency, borders, and presence of fluid/air in the lungs and abdomen. Percussion has been successfully used for the diagnosis of such potentially lethal conditions as traumatic and tension pneumothorax. This technique, however, has certain shortcomings, including limitations of the human ear and the subjectivity of the administrator, that lead to overall low sensitivity. Automation of the method by using a standardized percussion source and computerized classification of digitized signals would remove the subjective factor and other limitations of the technique. It would also enable rapid on-site diagnostics of pulmonary traumas when thorough clinical examination is impossible. This paper lays the groundwork for an objective signal classification approach based on a general physical model of a damped harmonic oscillator. Using this concept, critical parameters that effectively subdivide percussion signals into three main groups, historically known as "tympanic," "resonant," and "dull," are identified, opening the possibility for automated diagnostics of air/liquid inclusions in the thorax and abdomen. The key role of damping in forming the character of the percussion signal is investigated using a 3D thorax phantom. The contribution of the abdominal component into the complex multimode spectrum of chest percussion signals is demonstrated.


Assuntos
Auscultação/classificação , Percussão/classificação , Abdome/fisiologia , Acústica/instrumentação , Adulto , Ar , Feminino , Hemotórax/diagnóstico , Humanos , Masculino , Modelos Anatômicos , Pneumotórax/diagnóstico , Espectrografia do Som , Tórax/fisiologia , Adulto Jovem
12.
Head Neck ; 22(6): 599-608, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10941162

RESUMO

BACKGROUND: Chemotherapy is widely used in patients with recurrent head and neck cancer, but no clear markers are available that can predict response to treatment or survival in these patients. METHODS: Twenty-nine patients evaluated in this study had recurrent head and neck squamous carcinomas, previously treated with surgery and/or radiotherapy. Patients received either cisplatin and 5-fluorouracil (5-FU) (n = 15) or cisplatin and paclitaxel (Taxol) (n = 14). Expression of c-erbB2, p53, glutathione S-transferase pi, multidrug resistance-associated protein, thymidylate synthase, and glutathione synthetase were evaluated in biopsy tissues. RESULTS: Response to chemotherapy was significantly correlated with improved survival (progression-free survival, p =.0005; overall survival, p =. 007). Of the factors examined, expression of c-erbB2 was associated with significantly decreased progression-free survival (p =.023) and overall survival (p =.029). This was seen in patients treated with cisplatin/taxol but not in patients treated with cisplatin/5-FU. CONCLUSION: Expression of c-erbB2 may be a clinically useful predictor of survival in this group of patients.


Assuntos
Biomarcadores Tumorais/análise , Carcinoma de Células Escamosas/tratamento farmacológico , Carcinoma de Células Escamosas/mortalidade , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Neoplasias de Cabeça e Pescoço/mortalidade , Receptor ErbB-2/análise , Adulto , Idoso , Antimetabólitos Antineoplásicos/administração & dosagem , Antineoplásicos Fitogênicos/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Cisplatino/administração & dosagem , Feminino , Fluoruracila/administração & dosagem , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia , Paclitaxel/administração & dosagem , Prognóstico , Taxa de Sobrevida
13.
Clin Cancer Res ; 5(12): 4097-104, 1999 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-10632346

RESUMO

Neoadjuvant cisplatin-based chemotherapy has been widely used in the last decade for organ preservation or unresectable disease in advanced stage head and neck cancer. We examined the expression of a series of tumor markers that have been associated with chemotherapy resistance in pretreatment biopsies from 68 patients who received cisplatin-based neoadjuvant chemotherapy at either of two institutions. Patients received either cisplatin/5-fluorouracil (n = 49) or cisplatin/paclitaxel (n = 19). Expression of p53, glutathione S-transferase pi (GSTpi), thymidylate synthase (TS), c-erbB2, and multidrug resistance-associated protein was examined by immunohistochemistry. Expression of glutathione synthetase mRNA was measured by in situ hybridization. The overall response rate for cisplatin-based neoadjuvant treatment was 79%. The expression of several of the tumor markers was associated with resistance to neoadjuvant treatment, but none reached statistical significance. Overall survival (OS) was strongly correlated with the absence of p53 expression. The OS at 3 years was 81% in the p53-negative group, whereas it was 30% in the p53-positive group for patients treated with neoadjuvant chemotherapy (P < 0.0001). Expression of GST pi and TS was also significantly correlated with decreased OS after neoadjuvant treatment. At 3 years, the OS rate was 82% in the low GSTpi score group, compared to 46% in the high GSTpi score group (P = 0.0018). In the TS-negative group, the 3-year OS rate was 71% compared with 40% in the TS-positive group (P = 0.0071). We conclude that p53, GSTpi, and TS may be clinically important predictors of survival in patients receiving neoadjuvant chemotherapy for head and neck cancer.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma de Células Escamosas/tratamento farmacológico , Carcinoma de Células Escamosas/metabolismo , Glutationa Transferase/biossíntese , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Neoplasias de Cabeça e Pescoço/metabolismo , Isoenzimas/biossíntese , Timidilato Sintase/biossíntese , Proteína Supressora de Tumor p53/biossíntese , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/biossíntese , Carcinoma de Células Escamosas/enzimologia , Carcinoma de Células Escamosas/mortalidade , Cisplatino/administração & dosagem , Intervalo Livre de Doença , Feminino , Fluoruracila/administração & dosagem , Glutationa S-Transferase pi , Neoplasias de Cabeça e Pescoço/enzimologia , Neoplasias de Cabeça e Pescoço/mortalidade , Humanos , Masculino , Pessoa de Meia-Idade , Terapia Neoadjuvante , Paclitaxel/administração & dosagem , Estudos Retrospectivos , Resultado do Tratamento
14.
Med Sci Sports Exerc ; 23(1): 93-107, 1991 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-1997818

RESUMO

In this study we evaluated the physiological and biomechanical responses of "elite-national class" (i.e., group 1; N = 9) and "good-state class" (i.e., group 2; N = 6) cyclists while they simulated a 40 km time-trial in the laboratory by cycling on an ergometer for 1 h at their highest power output. Actual road racing 40 km time-trial performance was highly correlated with average absolute power during the 1 h laboratory performance test (r = -0.88; P less than 0.001). In turn, 1 h power output was related to each cyclists' VO2 at the blood lactate threshold (r = 0.93; P less than 0.001). Group 1 was not different from group 2 regarding VO2max (approximately 70 ml.kg-1.min-1 and 5.01 l.min-1) or lean body weight. However, group 1 bicycled 40 km on the road 10% faster than group 2 (P less than 0.05; 54 vs 60 min). Additionally, group 1 was able to generate 11% more power during the 1 h performance test than group 2 (P less than 0.05), and they averaged 90 +/- 1% VO2max compared with 86 +/- 2% VO2max in group 2 (P = 0.06). The higher performance power output of group 1 was produced primarily by generating higher peak torques about the center of the crank by applying larger vertical forces to the crank arm during the cycling downstroke. Compared with group 2, group 1 also produced higher peak torques and vertical forces during the downstroke even when cycling at the same absolute work rate as group 2. Factors possibly contributing to the ability of group 1 to produce higher "downstroke power" are a greater percentage of Type I muscle fibers (P less than 0.05) and a 23% greater (P less than 0.05) muscle capillary density compared with group 2. We have also observed a strong relationship between years of endurance training and percent Type I muscle fibers (r = 0.75; P less than 0.001). It appears that "elite-national class" cyclists have the ability to generate higher "downstroke power", possibly as a result of muscular adaptations stimulated by more years of endurance training.


Assuntos
Ciclismo , Lactatos/sangue , Resistência Física/fisiologia , Adolescente , Adulto , Fenômenos Biomecânicos , Peso Corporal , Humanos , Ácido Láctico , Masculino , Músculos/enzimologia , Análise de Regressão
15.
Percept Mot Skills ; 69(2): 659-70, 1989 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-2813015

RESUMO

H-reflex amplitudes were studied during the acquisition of a motor skill involving coordinated isometric plantarflexion at the ankle joints as subjects learned to trace a triangular pattern on an oscilloscope screen by controlling plantarflexion torque applied against load cells. Torque feedback was presented on a subject oscilloscope with the right foot controlling a vertical cursor and the left foot a horizontal cursor. Eleven subjects reached criterion performance. H-reflexes were recorded from the right soleus and timed to the initiation of soleus muscle activity to plantarflex the foot. Average time to complete one trial decreased from 9 sec. in the prelearning block to 4 sec. postlearning. No single learning strategy was evident as subjects varied widely in their levels of H-reflex amplitude, but during postlearning, H-reflex amplitude became consistent within subjects as tracing performance became faster and accurate.


Assuntos
Reflexo H , Aprendizagem/fisiologia , Destreza Motora/fisiologia , Reflexo Monosináptico , Adolescente , Adulto , Eletromiografia , Feminino , Pé/fisiologia , Humanos , Masculino , Músculos/fisiologia
16.
Drug Alcohol Depend ; 23(1): 31-40, 1989 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-2920664

RESUMO

The effects of ethanol (EtOH) on response components varying along a central vs. peripheral dimension were studied in five subjects. Reaction times (RTs) were fractionated by electromyographical recordings into premotor (central) and motor (peripheral, contractile) components. Highly practiced subjects performed a simple and discrimination RT task and related movement without significant impairment at the moderate blood ethanol concentration (BEC) (0.10%). At the higher BEC (0.17%), all components involving central processing (response time, RT and premotor time) were impaired in both simple and discrimination RT. More peripheral components (contractile time and movement time) were little affected. Contractile time was slowed slightly but significantly, but only in the combination of EtOH and the discrimination task which suggests that the stimulus discrimination stage of information processing can influence the activation of motor units involved in carrying out the movement.


Assuntos
Etanol/farmacologia , Desempenho Psicomotor/efeitos dos fármacos , Tempo de Reação/efeitos dos fármacos , Adulto , Consumo de Bebidas Alcoólicas/psicologia , Aprendizagem por Discriminação/efeitos dos fármacos , Relação Dose-Resposta a Droga , Eletromiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto
17.
J Gerontol ; 43(5): P121-6, 1988 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-3418038

RESUMO

Reaction time and its fractionated components were studied in two groups of older women who differ in their level of regular aerobic exercise. Significant group differences were found in all dependent variables indicating that in older women regular aerobic exercise is an important factor influencing the speed of their reactions to simple and discriminatory stimuli, and in the accompanying premotor time, contractile time, and speed of movement following the reaction responses.


Assuntos
Envelhecimento/fisiologia , Esforço Físico , Tempo de Reação/fisiologia , Eletromiografia , Feminino , Humanos , Pessoa de Meia-Idade
18.
J Mot Behav ; 12(3): 173-84, 1980 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15178528

RESUMO

Two experiments are presented in which different mechanisms controlling each limb in a bilateral arm response to a unilateral kinesthetic stimulus are postulated to occur. In Experiment 1, the limb serving as the stimulus are postulated to occur. In Experiment 1, the limb serving as the stimulus limb was described as operating with relative invariance by using a tightly coupled input-output reflexive pathway, whereas the nonstimulus limb appeared to be controlled by higher-order processing thought to be more susceptible to influences such as hemispheric specialization and stimulus expectancy. The differential control model was further tested in Experiment 2 by retaining the interhemispheric pathway of the unilateral kinesthetic stimulus but experimentally uncoupling the reflex mechanism from the stimulus side. Analyses of bilateral EMG premotor latencies under these conditions revealed that each response side can be controlled at separate levels-i.e., by a reflexive type mechanism or by higher-order processing when one of the response limbs is also the stimulus limb, both sides reflect behavior that is best described by an information processing type of voluntary control.

19.
Med Sci Sports ; 10(3): 218-22, 1978.
Artigo em Inglês | MEDLINE | ID: mdl-723515

RESUMO

Ages at menarche in 110 non-athletes, 59 high school atjletes, 53 college athletes, and 18 olympic volleyball candidates were determined through interview. The athletes attained menarche significantly later than the non-athletes (p less than .001), and the olympic athletes attained menarche significantly later than the high school and college athletes (p less than .001). The high school and college athletes did not differ significantly in the mean age at menarche. When menarche in college athletes was analyzed by specific sports, the small samples of participants in golf (n = 4), volleyball (n = 7), swimming (n = 7), basketball (n = 16), and gymnastics and track (n = 6) did not differ significantly from each other in the mean age at menarche. The olympic volleyball aspirants attained menarche significantly later than all sport-specific groups (p less than .05 to p less than .001) except the gymnastics-track and tennis (n = 13) athletes. Smaller samples of non-athletes (n = 27) and college athletes (n = 21 from volleyball and basketball), plus the olympic athletes were also interviewed regarding selected menstrual characteristics. Although the athletes reported a greater incidence of dysmenorrhea and menstrual irregularity, none of the chi square values comparing the three groups was significant.


Assuntos
Menarca , Menstruação , Medicina Esportiva , Adolescente , Fatores Etários , Criança , Dismenorreia/epidemiologia , Feminino , Humanos , Estudos Retrospectivos , Maturidade Sexual , Texas
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