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1.
Sports Health ; 13(1): 25-30, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32631208

RESUMO

BACKGROUND: The relationships between sport specialization, physical activity, sleep, and illness in younger athletes are unknown. Therefore, the purpose of this study was to evaluate the independent effects of sport specialization, sleep, and physical activity on illness in middle school athletes. HYPOTHESIS: Decreased sleep, decreased physical activity, and higher levels of sport specialization will be associated with an increased risk of illness among middle school athletes. STUDY DESIGN: Prospective cohort study. LEVEL OF EVIDENCE: Level 4. METHODS: Parents of middle school-aged children reported baseline sport specialization (low, moderate, or high) as well as sleep duration, physical activity, and illnesses every week throughout the academic year. A mixed-effects logistic regression model was used to assess the association between illness and specialization while accounting for sleep and physical activity for the prior week as fixed effects and each individual as a random effect. RESULTS: A total of 233 children (mean age, 12.1 ± 1.2 years; 61% male) participated, of whom 41%, 25%, and 34% were categorized as low, moderate, and high specialization, respectively. The proportion of individuals who experienced illness did not differ by specialization level (low, 76%; moderate, 70%; high, 59%; P = 0.064). In the multivariable model, the odds of illness compared with the low specialization group was not significantly different for moderate (odds ratio [OR], 0.93; 95% CI, 0.70-1.23; P = 0.61) or high specialization (OR, 0.76; 95% CI, 0.56-1.03; P = 0.073). A decreased risk of illness was associated with greater prior week sleep (OR, 0.79; 95% CI, 0.69-0.91; P < 0.001) and physical activity (OR, 0.94; 95% CI, 0.92-0.96; P < 0.001). CONCLUSION: Sport specialization is not associated with an increased risk of illness among middle school athletes, while increased sleep duration and physical activity appear to reduce the risk of illness. CLINICAL RELEVANCE: Interventions to promote physical activity and improve sleep may reduce the risk of illness in early adolescent athletes.


Assuntos
Exercício Físico , Privação do Sono/fisiopatologia , Especialização , Esportes Juvenis/fisiologia , Adolescente , Criança , Transtornos Traumáticos Cumulativos/fisiopatologia , Feminino , Humanos , Masculino , Condicionamento Físico Humano/fisiologia , Estudos Prospectivos , Fatores de Risco
2.
PLoS One ; 15(11): e0242385, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33180872

RESUMO

OBJECTIVE: The aims of the present study were: 1) to calculate the change of direction (COD) deficit (using a modified version of the 505 test and 10 m sprint time), and (2) to examine the differences in linear sprint, jump and COD performances, as well as COD deficit, between under-13 (U13) and under-15 (U15) male handball players. METHODS: One hundred and nineteen young male handball players (under-13 [U13; n = 82] and under-15 [U15; n = 37]). Tests included anthropometric measurements, countermovement jump (CMJ), triple leg-hop for distance, linear sprint test (5, 10 and 20 m), and a modified version of the 505 COD test. RESULTS: Results showed moderate to very large differences (P < 0.05) in age, predicted age at peak height velocity (APHV), distance from PHV (DPHV), height, and body mass between the age categories. Moreover, U15 players demonstrated higher performances in all jump tests and lower sprint times in 10- (ES = 0.84) and 20-m (ES = 0.51) and a higher 505 deficit (ES = 0.38) than the U13 players (P < 0.05). However, no significant differences were observed for the 505 COD test between groups (ES = 0.12; P > 0.05). CONCLUSIONS: Our results suggest that during the transition from pre- to post-puberty, young handball players should focus on transferring their progressive improvements in strength, speed, and power capacities to COD performance.


Assuntos
Fatores Etários , Desempenho Atlético/fisiologia , Aptidão Física/fisiologia , Adolescente , Atletas , Criança , Teste de Esforço , Humanos , Masculino , Força Muscular/fisiologia , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiologia , Condicionamento Físico Humano/métodos , Condicionamento Físico Humano/fisiologia , Exercício Pliométrico/métodos
3.
Apunts, Med. esport (Internet) ; 55(207): 111-114, jul.-sept. 2020. ilus, tab
Artigo em Inglês | IBECS | ID: ibc-194712

RESUMO

Performing the rehabilitation of a player on a surface different from the normally used by the athlete in her/his sport is beneficial. By recruiting more muscle fibers in the new surface, the rehabilitation process is enhanced. Here, we describe the electromyography (EMG) data of anterior and posterior chains during workouts on two different surfaces: sand and artificial turf. We recorded data using a Myontec EMG device of two anterior cruciate ligament (ACL) injured women's soccer players. Player 1 was injured on her left leg in the ACL and the patellar tendon, and player 2 was injured on her right leg in the ACL and semitendinosus plasty. The EMG results of player 1 showed an increase in the activation of the cross pattern (i.e. left hamstring and right gluteus) of the posterior chain. Similarly, the EMG data of player 2 showed an increase in the activation of the left quadriceps (the antagonist muscle of her injured leg) of the anterior chain. In conclusion, in both players the muscle group most activated during rehabilitation was the antagonist of the injured leg's muscle, regardless of the surface used


No disponible


Assuntos
Humanos , Feminino , Adolescente , Exercício Físico/fisiologia , Condicionamento Físico Humano/fisiologia , Músculos/fisiologia , Ligamento Cruzado Anterior/cirurgia , Terapia por Exercício/métodos , Medicina Física e Reabilitação/métodos , Ligamento Cruzado Anterior/diagnóstico por imagem
4.
J Sports Med Phys Fitness ; 60(8): 1057-1064, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32955831

RESUMO

BACKGROUND: Rock climbers are characterized by enhanced forearm fatigue resistance. This study compared the forearm isometric force of rock climbers (RC), strength-matched power lifters (PL) and aerobically trained (AT) athletes to determine the contribution of muscle oxygen desaturation during ischemia. METHODS: Aerobically trained athletes (N.=6, 23±1 years, 77±1 kg), power lifters (N.=7, 24±1 years, 80±3 kg) and rock climbers (N.=8, 25±2 years, 74±2 kg) took part in a controlled forearm ischemic occlusion (5 min) assessment using near infrared spectroscopy. In addition, three fatigue protocols were completed: protocol 1, sustained maximal voluntary contraction (MVC) until exhaustion; protocol 2, sustained 40% MVC for 3 mins duration; protocol 3, an intermittent 40% MVC (5-s contraction, 5-s recovery) for a duration of 3 mins. Forearm contractile fatigue was quantified as the reduction in MVC. RESULTS: MVC was equivalent between groups (P>0.05). Sustained MVC force (time to decline 50% MVC) was longer in the RC versus AT (AT: 35±5, PL: 46±6, RC: 54±4 s, P<0.05) and both AT and PL for sustained 40% MVC (AT: 56±9, RT: 62±8, RC: 87±7 s, P<0.05). Reduction in MVC was less in RC post intermittent 40% contractions (P<0.05). Oxygen desaturation half-time was longer in the RC versus AT (AT: 65±9, RT: 86±7, RC: 99±7 s, P<0.05) and this was associated with time to 50% MVC (P<0.05, r2=0.53) and time to 40% MVC task failure (P<0.05, r2=0.32). CONCLUSIONS: Rock climbers' enhanced isometric fatigue-resistance and ability to maintain MVC was associated with a lower oxygen consumption of the forearm flexors during the ischemic state. This suggests a training adaptation involving intracellular oxygen consumption.


Assuntos
Antebraço/fisiologia , Montanhismo/fisiologia , Fadiga Muscular/fisiologia , Músculo Esquelético/fisiologia , Adaptação Fisiológica , Adulto , Dedos/fisiologia , Antebraço/irrigação sanguínea , Antebraço/diagnóstico por imagem , Humanos , Contração Isométrica/fisiologia , Masculino , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/diagnóstico por imagem , Consumo de Oxigênio , Condicionamento Físico Humano/fisiologia , Espectroscopia de Luz Próxima ao Infravermelho , Levantamento de Peso/fisiologia , Adulto Jovem
5.
J Sports Med Phys Fitness ; 60(8): 1159-1166, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32955842

RESUMO

BACKGROUND: Endothelial function assessment may provide important insights into the cardiovascular function and long-term effects of exercise training. Many studies have investigated the possible negative effects on cardiovascular function due to extreme athletic performance, leading to undesirable effects. The purposes of this study were to investigate the acute effects of maximal intensity exercise on endothelium-dependent vasodilation, and to understand the patterns of flow-mediated dilation (FMD) change following maximal exercise in elite female athletes with a high-volume training history. METHODS: Twenty-six elite female soccer players (mean age, 22±4 years; BMI, 21±2 kg/m2; VO2max, 41±4 mL/kg/min) were evaluated. Brachial artery FMD was determined using high-resolution ultrasound at rest, and after 15 and 60 min of maximal cardiopulmonary exercise (CPX) testing on a treadmill. Flow velocity was measured at baseline and during reactive hyperemia at the same periods. RESULTS: Rest FMD was 12.4±5.5%. Peak diameter in response to reactive hyperemia was augmented after 15 min of CPX (3.5±0.4 vs. 3.6±0.4 mm, P<0.05), returning to resting values after 60 min. However, %FMD did not change among time periods. There were two characteristic patterns of FMD response following CPX. Compared to FMD at rest, half of the subjects responded with an increased FMD following maximum exercise (10.5±6.1 vs. 17.8±7.5%, P<0.05). The other subjects demonstrated a reduced FMD response following maximum exercise (14.2±4.3 vs. 10.9±3.2%, P<0.01). CONCLUSIONS: These results indicate that elite female soccer players presented robust brachial artery FMD at rest, with a heterogeneous FMD response to acute exercise with a 50% FMD improvement rate.


Assuntos
Endotélio Vascular/fisiologia , Exercício Físico/fisiologia , Condicionamento Físico Humano/fisiologia , Futebol/fisiologia , Vasodilatação/fisiologia , Adulto , Velocidade do Fluxo Sanguíneo , Artéria Braquial/diagnóstico por imagem , Artéria Braquial/fisiologia , Teste de Esforço , Feminino , Humanos , Fluxo Sanguíneo Regional/fisiologia , Adulto Jovem
6.
J Sports Sci Med ; 19(3): 613-619, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32874114

RESUMO

This study quantified the match-play activity profiles of international touch rugby and different positional physical outputs in comparison with training specificity. Between November 2019 and January 2020, 82 half-matches and 173 training global positioning system data from 16 national male touch rugby players (mean ± SD: age 23.71 ± 3.90 years, height 1.73 ± 0.05 m, weight 65.38 ± 9.08 kg, touch rugby training experience 6.09 ± 3.31 years) were recorded. The distance covered by wings in half-match (1676.66 ± 444.80 m) was more than that of link (1311.35 ± 223.59 m) and middle (1383.52 ± 246.55 m) by a large effect (partial η 2 = 0.19), which was mainly attributed to walking and jogging (< 4.00 m·s-1). Meanwhile, the middles covered more running distance (4.00-5.50 m·s-1) than other positions. No significant positional group difference was observed for distance covered >5.50 m·s-1, maximum velocity, and the ratio of acceleration and deceleration in matches. Training intensity was close to the match-play outputs only for the high-speed running distance at ≥ 5.50 m·s-1. However, the training activity pattern consistently showed a disparity with the match-play outputs, in terms of shorter normalized training distance covered, less recovery distance covered at ≤ 5.50 m·s-1, higher maximum velocity, and heavier weighting to acceleration in training activities. The current study highlights for the first time that in-match deceleration capacity and active recovery pacing strategy may be essential to touch rugby players. The data provided practitioners a deeper understanding of the physical demands of national touch rugby and allowed them to align the training with the match-play intensity.


Assuntos
Comportamento Competitivo/fisiologia , Futebol Americano/fisiologia , Sistemas de Informação Geográfica , Condicionamento Físico Humano/fisiologia , Corrida/fisiologia , Análise e Desempenho de Tarefas , Aceleração , Adulto , Desaceleração , Humanos , Corrida Moderada/fisiologia , Masculino , Estudos Prospectivos , Caminhada/fisiologia , Adulto Jovem
7.
J Strength Cond Res ; 34(8): 2128-2135, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32735423

RESUMO

Rodríguez-Fernández, A, Villa, JG, Sánchez-Sánchez, J, and Rodríguez-Marroyo, JA. Effectiveness of a generic vs. specific program training to prevent the short-term detraining on repeated-sprint ability of youth soccer players. J Strength Cond Res 34(8): 2128-2135, 2020-The aim of this study was to analyze the effects of 2 short-term training programs to prevent the negative effect of detraining on repeated-sprint ability (RSA) performance. The study was performed during a 2-week midseason break without official matches. Forty-five youth soccer players (17.7 ± 0.8 years, 175.4 ± 5.5 cm, and 67.2 ± 5.1 kg) were split into 3 groups during the intervention period: inactivity group (IN; N = 16), generic high-intensity training group (GG; N = 15), and specific training group (SG; N = 14). IN was instructed to avoid performing physical activity during the 2-week training intervention. However, GG and SG performed 8 training sessions. GG performed a generic aerobic interval training consisting of 4 repetitions of 4 minutes of exercise at 90-95% of maximal heart rate. SG performed a specific conditioning through small-sided games (4 vs. 4, 4 × 4-minute) and repeated sprints (6 × 30-m). Testing sessions included an RSA test and a Yo-Yo intermittent recovery test level 1 (YYIR1). Repeated-sprint ability performance only improved after the training intervention in SG (∼2%, p < 0.01, (Equation is included in full-text article.)= 0.23-0.25). Both GG and IN declined their performance in post-test (∼2%, p < 0.01, (Equation is included in full-text article.)= 0.19-0.22). No significant effect, group × time, was analyzed for YYIR1 performance. This study suggests that only specific training, based on small-sided games and repeated sprints, leads to short-term improvements on RSA performance in youth soccer players.


Assuntos
Desempenho Atlético/fisiologia , Corrida/fisiologia , Futebol/fisiologia , Adolescente , Exercício Físico/fisiologia , Humanos , Masculino , Condicionamento Físico Humano/fisiologia
8.
Nat Metab ; 2(9): 805-816, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32747791

RESUMO

The coordination of nutrient sensing, delivery, uptake and utilization is essential for maintaining cellular, tissue and whole-body homeostasis. Such synchronization can be achieved only if metabolic information is communicated between the cells and tissues of the entire organism. During intense exercise, the metabolic demand of the body can increase approximately 100-fold. Thus, exercise is a physiological state in which intertissue communication is of paramount importance. In this Review, we discuss the physiological processes governing intertissue communication during exercise and the molecules mediating such cross-talk.


Assuntos
Exercício Físico/fisiologia , Redes e Vias Metabólicas/fisiologia , Animais , Encéfalo/fisiologia , Homeostase/fisiologia , Humanos , Músculo Esquelético/fisiologia , Condicionamento Físico Animal/fisiologia , Condicionamento Físico Humano/fisiologia
9.
J Orthop Sports Phys Ther ; 50(8): 415-417, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32736496

RESUMO

SYNOPSIS: Repeated purposeful heading in soccer has come under increased scrutiny as concerns surrounding the association with long-term neurodegenerative disorders in retired players continue to grow. Although a causal link between heading and brain health has not been established, the "precautionary principle" supports the notion that soccer governing bodies and associations should consider implementing pragmatic strategies that can reduce head impact during purposeful heading in youth soccer while this relationship is being investigated. This Viewpoint discusses the current evidence to support low-risk head impact reduction strategies during purposeful heading to protect young, developing players, and how such strategies could be implemented now while research and debate continue on this topic. J Orthop Sports Phys Ther 2020;50(8):415-417. doi:10.2519/jospt.2020.0608.


Assuntos
Cabeça/fisiologia , Destreza Motora/fisiologia , Futebol/fisiologia , Adolescente , Fatores Etários , Criança , Comportamento Competitivo/fisiologia , Feminino , Humanos , Masculino , Força Muscular , Músculos do Pescoço/fisiologia , Doenças Neurodegenerativas/prevenção & controle , Condicionamento Físico Humano/fisiologia , Fatores de Risco , Futebol/lesões , Equipamentos Esportivos
10.
Int J Sports Med ; 41(13): 936-943, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32643774

RESUMO

This study aimed to test if the non-oxidative energy supply (estimated by the accumulated oxygen deficit) is associated with an index of muscle lactate accumulation during exercise, muscle monocarboxylate transporter content and the lactate removal ability during recovery in well-trained rowers. Seventeen rowers completed a 3-min all-out exercise on rowing ergometer to estimate the accumulated oxygen deficit. Blood lactate samples were collected during the subsequent passive recovery to assess individual blood lactate curves, which were fitted to the bi-exponential time function: La(t)= [La](0)+A1·(1-e-γ 1 t)+A2·(1-e-γ 2 t), where the velocity constants γ1 and γ2 (min-1) denote the lactate exchange and removal abilities during recovery, respectively. The accumulated oxygen deficit was correlated with the net amount of lactate released from the previously active muscles (r =0.58, P<0.05), the monocarboxylate transporters MCT1 and MCT4 (r=0.63, P<0.05) and γ2 (r=0.55, P<0.05). γ2 and the lactate release rate at exercise completion were negatively correlated with citrate synthase activity. These findings suggest that the capacity to supply non-oxidative energy during supramaximal rowing exercise is associated with muscle lactate accumulation and transport, as well as lactate removal ability.


Assuntos
Ácido Láctico/metabolismo , Transportadores de Ácidos Monocarboxílicos/metabolismo , Proteínas Musculares/metabolismo , Músculo Esquelético/metabolismo , Consumo de Oxigênio , Simportadores/metabolismo , Esportes Aquáticos/fisiologia , Metabolismo Energético , Humanos , Concentração de Íons de Hidrogênio , Ácido Láctico/sangue , Condicionamento Físico Humano/fisiologia , Adulto Jovem
11.
J Orthop Sports Phys Ther ; 50(7): 381-387, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32605467

RESUMO

OBJECTIVE: To investigate change in shoulder rotation strength from preseason to midseason during a competitive season in youth elite handball players without shoulder problems. DESIGN: Prospective cohort study. METHODS: Players (n = 292, 45% female, 14-18 years of age) without shoulder problems from Danish youth elite handball clubs were assessed in the preseason and midseason. We measured isometric shoulder strength using handheld dynamometry in internal rotation (IR) and external rotation (ER) in supine, with the shoulder abducted 90° in neutral rotation and in 30° of IR. The primary outcome was the change in corresponding ER/IR ratio. RESULTS: The mean ER/IR ratios increased from preseason to midseason in neutral rotation (male player difference, 0.02; 95% confidence interval [CI]: -0.01, 0.06; female player difference, 0.05; 95% CI: 0.01, 0.09) and in 30° of IR (male player difference, 0.15; 95% CI: 0.11, 0.20; female player difference, 0.12; 95% CI: 0.07, 0.17). The change in ER/IR ratio may be explained by an increase in ER strength in female players and a decrease in IR strength in male players. The amount of change in ER/IR ratio over the season was greater than individual measurement error metrics for 45% to 66% of the players. CONCLUSION: Shoulder rotation strength ratios changed during a competitive season in Danish youth elite handball players. J Orthop Sports Phys Ther 2020;50(7):381-387. doi:10.2519/jospt.2020.9183.


Assuntos
Comportamento Competitivo/fisiologia , Força Muscular , Ombro/fisiologia , Esportes/fisiologia , Adolescente , Feminino , Humanos , Masculino , Condicionamento Físico Humano/fisiologia , Estudos Prospectivos , Valores de Referência , Rotação , Fatores Sexuais , Fatores de Tempo
12.
Int J Sports Med ; 41(11): 766-770, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32650343

RESUMO

The purpose of this study was to examine body composition of National Collegiate Athletic Association Division I female soccer players by position and season. One hundred seventy-five female athletes were categorized by positions of forward (n=47), midfielder (n=51), defender (n=57), and goalkeeper (n=20). A dual X-ray absorptiometry scan assessed percent body fat, total lean mass, total fat mass, arm and leg lean mass and fat mass, and visceral adipose tissue. Goalkeepers had significantly higher total, arm, and leg lean mass and fat mass compared to all other positions (p<0.05). For seasonal changes, body fat percentage was significantly higher in winter off-season (26.7%) compared to summer off-season (25.7%) and pre-season (25.8%; p<0.01) for all positions. Total and leg lean mass was significantly lower in winter off-season compared to all other seasons, and total lean mass was significantly higher in summer off-season than pre-season (p<0.01). Overall, goalkeepers were significantly different than all other positions. Body fat percentage increased and lean mass decreased in winter off-season indicating potential undesired changes in training and/or nutrition over the break whereas lean mass was the highest in summer off-season potentially reflecting the emphasis on resistance training and increased volume of training.


Assuntos
Distribuição da Gordura Corporal , Índice de Massa Corporal , Comportamento Competitivo/fisiologia , Futebol/fisiologia , Absorciometria de Fóton , Feminino , Humanos , Condicionamento Físico Humano/fisiologia , Estações do Ano , Adulto Jovem
13.
J Sports Sci ; 38(20): 2367-2373, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32608344

RESUMO

The lateral tilt of the arms accompanied by trunk lateral tilt is a typical blocking manoeuvre in volleyball. However, during this unanticipated blocking movement, an associated risk of ACL injury may result. The aim of the present study was to compare associative ACL risk factors at the initial contact and the first and second peak of VGRF during an unanticipated blocking movement with different arm positions. Synchronized kinematic and kinetic data were collected for each trial of each condition. Student paired t-tests and effect size were used to determine differences between two conditions (S - with arms straight up from the body) and (T - with the arms and trunk laterally tilted). The results showed that the T condition significantly decreases knee flexion, increases VGRF at the foot contact, first peak force and increases the valgus moment at the first peak force. The values of the associated risk factors for a non-contact ACL injury appear to be related to the tilted arm position accompanied by trunk tilt towards to right lower limb during landing. The players should be taught to land with greater knee flexion and, if possible, a double-leg landing to decrease right lower limb loading during the blocking manoeuvre.


Assuntos
Lesões do Ligamento Cruzado Anterior/fisiopatologia , Movimento/fisiologia , Voleibol/fisiologia , Adolescente , Braço/fisiologia , Fenômenos Biomecânicos , Feminino , Humanos , Cinética , Joelho/fisiologia , Tutoria , Destreza Motora/fisiologia , Condicionamento Físico Humano/fisiologia , Fatores de Risco , Estudos de Tempo e Movimento , Tronco/fisiologia
14.
Rev. int. med. cienc. act. fis. deporte ; 20(78): 299-320, jun. 2020. graf, ilus, tab
Artigo em Espanhol | IBECS | ID: ibc-194784

RESUMO

Este trabajo pretende dos objetivos: 1º) dar una visión pedagógica de la complejidad relativa al tratamiento matemático de la variabilidad de la frecuencia cardiaca y 2º) analizar si el tratamiento matemático de la señal RR (distancia entre dos ondas R del electrocardiograma) tiene una base fisiológica. Se revisan los mecanismos fisiológicos que explican uno de los fenómenos de base para el análisis de la variabilidad: la arritmia sinusal respiratoria. Se analizan las bases matemáticas, así como los métodos matemáticos de valoración, de la variabilidad. Finalmente, se realiza una revisión del significado fisiológico de las bandas de frecuencia obtenidas mediante las diversas metodologías del tratamiento de la señal RR. No está claro si los métodos matemáticos de tratamiento de la señal RR pueden ser una herramienta de valoración de la función vegetativa. Por ello, debemos tener precaución al interpretar esta variable, sobre todo en el contexto del ejercicio físico y entrenamiento


This work has two objectives: 1) to give a pedagogical view about the complexity of the mathematical treatment of heart rate variability and 2) to analyze whether the mathematical treatment of the RR signal (distance between two R waves shown in an electrocardiogram) has a physiological basis. We reviewed the physiological mechanisms that explain one of the basic phenomena for the analysis of heart rate variability: respiratory sinus arrhythmia. The elementary mathematical bases as well as the mathematical methods of assessing the variability are analyzed. Finally, we offer a critical review of the physiological significance of the frequency bands obtained by the various methodologies of the RR signal processing. It is not clear whether the mathematical methods of RR signal processing can be an assessment tool for vegetative function. Therefore, this variable must be interpreted with caution, especially in the context of physical exercise and training


Assuntos
Humanos , Frequência Cardíaca/fisiologia , Exercício Físico/fisiologia , Condicionamento Físico Humano/fisiologia , Atividade Motora/fisiologia , Monitorização Fisiológica
15.
Med Sci Sports Exerc ; 52(7): 1629-1638, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32541378

RESUMO

INTRODUCTION: Regulatory efforts toward reducing concussion risk have begun to focus on decreasing the number of head impacts (i.e., head impact burden) sustained by athletes in contact sports. To that end, in 2018, the NCAA decreased the number of preseason on-field team activities for Division I teams from 29 to 25. The objective of the current study was to quantify changes in practice schedule and head impact exposure between the 2017 and 2018 football preseasons. METHODS: Athletes from five NCAA Division I football teams (n = 426) were consented and enrolled. RESULTS: On average, athletes participated in 10% fewer contact practices in 2018. However, the effect of this ruling on preseason head impact burden was mixed. Across all athletes, the total preseason head impact burden was essentially the same from 2017 to 2018. However, this study revealed significant team-by-team differences in preseason head impact burden, with one team demonstrating a 35% increase in the average number of recorded head impacts from 2017 to 2018, despite a modest decrease in the number of contact practices. Other teams had similar or decreased head impact burden. CONCLUSIONS: Team-based differences in total preseason head impact burden were attributable to changes in daily practice schedule, with longer practice durations and more intense contact practice sessions contributing to increases in daily head impact exposure that, in turn, led to greater preseason head impact burden. Results of this study have highlighted the difficulty in decreasing contact sport head impact exposure through rule changes targeted at limiting on-field team activities. Future efforts aimed specifically at contact practice duration, daily head impact exposure, or limiting time in specific drills may be more effective at reducing total preseason head impact burden.


Assuntos
Concussão Encefálica/prevenção & controle , Futebol Americano/fisiologia , Cabeça/fisiologia , Condicionamento Físico Humano , Fenômenos Biomecânicos , Concussão Encefálica/fisiopatologia , Humanos , Política Organizacional , Condicionamento Físico Humano/métodos , Condicionamento Físico Humano/fisiologia , Comportamento de Redução do Risco , Esportes , Fatores de Tempo
16.
Int J Sports Med ; 41(12): 839-845, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32590846

RESUMO

The effects of wearing an intra-oral device on several ventilatory and fatigue markers have been reported for a variety of sports. The quality of the figures performed in synchronized swimming is directly affected by fatigue, and can be monitored during training sessions (TS). The aim of the study was to investigate the acute effects of wearing customized intra-oral devices on heart rate variability, rating of perceived exertion, blood lactate accumulation, and salivary cortisol production during a competitive training session. Twelve highly trained elite female athletes (age: 21.0±3.6 years) participated in the study. Fatigue markers were assessed at the beginning and at the end of the 3rd and 5th afternoon TS for that week, once with and once without an intra-oral device, in random order. Salivary cortisol levels were higher in relation to the baseline in the intra-oral device condition (P<0.05) but not in athletes without an intra-oral device. No differences between conditions were found in rating of perceived exertion (P=0.465) and blood lactate (P=0.711). No time or condition interactions or main effects were shown for heart rate variability. Thus, there is no evidence that wearing a low-arch intra-oral device is a good recommendation for high-standard athletes performing long and stressful routines.


Assuntos
Comportamento Competitivo/fisiologia , Protetores Bucais , Condicionamento Físico Humano/fisiologia , Natação/fisiologia , Desenho de Equipamento , Feminino , Frequência Cardíaca , Humanos , Hidrocortisona/metabolismo , Arcada Osseodentária , Ácido Láctico/sangue , Percepção/fisiologia , Condicionamento Físico Humano/métodos , Esforço Físico/fisiologia , Ventilação Pulmonar , Saliva/metabolismo , Adulto Jovem
17.
Int J Sports Med ; 41(12): 824-831, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32599642

RESUMO

This study investigated acute hemodynamic, plasma volume and immunological responses to four loading protocols: sauna only, and sauna after endurance, strength or combined endurance and strength exercise. Twenty-seven healthy, slightly prehypertensive men (age 32.7±6.9 years) were measured at PRE, MID (after exercise), POST, POST30min and POST24h. The measurements consisted systolic and diastolic blood pressure, heart rate, body temperature and concentrations of high-sensitive C-reactive protein, white blood cells and plasma volume measurements. Endurance+sauna showed significant decreases in systolic blood pressure at POST (-8.9 mmHg), POST30min (-11.0 mmHg) and POST24h (-4.6 mmHg). At POST30min, significant decreases were also observed in sauna (-4.3 mmHg) and combined+sauna (-7.5 mmHg). Diastolic blood pressure decreased significantly from -5.4 to -3.9 mmHg at POST in all loadings. Plasma volume decreased significantly at MID in all exercise loadings and at POST in endurance+sauna and strength+sauna. Plasma volume increased significantly (p < 0.01) in endurance+sauna and combined+sauna at POST24h. White blood cells increased following all exercise+sauna loadings at MID, POST and POST30min, whereas high sensitive C-reactive protein showed no changes at any measurement point. The combination of endurance exercise and sauna showed the greatest positive effects on blood pressure. Both loadings including endurance exercise increased plasma volume on the next day.


Assuntos
Exercício Físico/fisiologia , Hemodinâmica , Banho a Vapor , Adulto , Pressão Sanguínea , Temperatura Corporal , Proteína C-Reativa/metabolismo , Frequência Cardíaca , Humanos , Contagem de Leucócitos , Masculino , Neutrófilos , Condicionamento Físico Humano/métodos , Condicionamento Físico Humano/fisiologia , Resistência Física/fisiologia , Volume Plasmático , Treinamento de Resistência
18.
Sports Health ; 12(4): 334-340, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32525466

RESUMO

BACKGROUND: Female runners are at increased risk of stress fractures (SFs) compared with men. Literature is lacking with regard to best practice for preventing and treating SFs in women. The purpose of the study was to compare physiological measures and running-related factors between women of various ages and running abilities with and without a history of running-related SFs. HYPOTHESIS: Women with and without SF histories will differ with regard to medical and menstrual history, bone health, body composition, nutrition, and running history. STUDY DESIGN: Prospective cohort study. LEVEL OF EVIDENCE: Level 2. METHODS: A total of 20 female runners with SF histories were matched based on age and running distance with 20 women without SF histories. Data included medical, menstrual, running, injury, and nutritional histories; blood histology related to nutritional, hormonal, and bone-related risk factors; and bone density, fat, and lean tissue using dual energy x-ray absorptiometry. Paired t tests were used to examine differences between women with and without SF histories, and Spearmen correlations were conducted to examine relationships between physiological factors. RESULTS: Women with SF histories had lower hip bone mineral density compared with women without SF histories (P < 0.05). SF history was moderately correlated with menstrual changes during increased training times (r = 0.580; P < 0.0001) but was not correlated with any other physiological factor. There was a moderate correlation within the SF group (r = 0.65; P = 0.004) for bone markers for resorption and formation both increasing, indicating increased bone turnover. CONCLUSION: Female runners with low hip bone mineral density, menstrual changes during peak training, and elevated bone turnover markers may be at increased risk of SF. CLINICAL RELEVANCE: Female runners need routine screening for risks associated with SF occurrence. As bone mineral density and bone turnover markers are not routinely assessed in this population, important risk factors may be missed.


Assuntos
Fraturas de Estresse/fisiopatologia , Corrida/fisiologia , Adulto , Biomarcadores/sangue , Distribuição da Gordura Corporal , Índice de Massa Corporal , Densidade Óssea/fisiologia , Remodelação Óssea/fisiologia , Feminino , Humanos , Menstruação , Pessoa de Meia-Idade , Condicionamento Físico Humano/fisiologia , Projetos Piloto , Estudos Prospectivos , Fatores de Risco , Fenômenos Fisiológicos da Nutrição Esportiva , Adulto Jovem
19.
Int J Sports Med ; 41(11): 736-743, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32485779

RESUMO

Injuries of runners reduce the ability to train and hinder competing. Literature shows that the relation between potential risk factors and injuries are not definitive, limited, and inconsistent. In team sports, workload derivatives were identified as risk factors. However, there is an absence of literature in running on workload derivatives. This study used the workload derivatives acute workload, chronic workload, and acute: chronic workload ratios to investigate the relation between workload and injury risk in running. Twenty-three competitive runners kept a daily training log for 24 months. The runners reported training duration, training intensity and injuries. One-week (acute) and 4-week (chronic) workloads were calculated as the average of training duration multiplied by training intensity. The acute:chronic workload ratio was determined dividing the acute and chronic workloads. Results show that a fortnightly low increase of the acute:chronic workload ratio (0.10-0.78) led to an increased risk of sustaining an injury (p<0.001). Besides, a low increase of the acute:chronic workload ratio (0.05-0.62) between the second week and third week before an injury showed an association with increased injury risk (p=0.013). These findings demonstrate that the acute:chronic workload ratio relates to injury risk.


Assuntos
Comportamento Competitivo/fisiologia , Condicionamento Físico Humano/fisiologia , Corrida/lesões , Traumatismos em Atletas/fisiopatologia , Feminino , Humanos , Masculino , Percepção/fisiologia , Condicionamento Físico Humano/métodos , Esforço Físico/fisiologia , Fatores de Risco , Fatores de Tempo , Adulto Jovem
20.
Int J Sports Med ; 41(11): 759-765, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32492734

RESUMO

A combination of yoga and blood flow restriction, each of which elicits marked pressor responses, may further increase blood pressure and myocardial oxygen demand. To determine the impact of a combination of yoga and blood flow restriction on hemodynamic responses, twenty young healthy participants performed 20 yoga poses with/without blood flow restriction bands placed on both legs. At baseline, there were no significant differences in any of the variables between the blood flow restriction and non-blood flow restriction conditions. Blood pressure and heart rate increased in response to the various yoga poses (p<0.01) but were not different between the blood flow restriction and non-blood flow restriction conditions. Rate-pressure products, an index of myocardial oxygen demand, increased significantly during yoga exercises with no significant differences between the two conditions. Rating of perceived exertion was not different between the conditions. Blood lactate concentration was significantly greater after performing yoga with blood flow restriction bands (p=0.007). Cardio-ankle vascular index, an index of arterial stiffness, decreased similarly after yoga exercise in both conditions while flow-mediated dilation remained unchanged. In conclusion, the use of lower body blood flow restriction bands in combination with yoga did not result in additive or synergistic hemodynamic and pressor responses.


Assuntos
Pressão Sanguínea , Hemodinâmica , Condicionamento Físico Humano/métodos , Fluxo Sanguíneo Regional , Coxa da Perna/irrigação sanguínea , Ioga , Adolescente , Adulto , Estudos Cross-Over , Endotélio Vascular/fisiologia , Feminino , Frequência Cardíaca , Humanos , Ácido Láctico/sangue , Masculino , Miocárdio/metabolismo , Consumo de Oxigênio , Percepção/fisiologia , Condicionamento Físico Humano/fisiologia , Esforço Físico/fisiologia , Rigidez Vascular , Vasodilatação , Adulto Jovem
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