Cardiac Autonomic Modulation in Response to Muscle Fatigue and Sex Differences During Consecutive Competition Periods in Young Swimmers: A Longitudinal Study.

Objective: To study the differences in cardiac autonomic modulation in response to muscle fatigue caused by high-intensity exercise during two consecutive competition periods in young swimmers. Methods: Twenty-six competitive swimmers, selected by their training volume, were separated in two groups, females (n = 12 [46%], age: 13.5 ± 1.4 years) and males (n = 14 [54%], age: 13.9 ± 1.7 years), aged between 10 and 16 years, were evaluated five times as follow: (i) 21 days before the first competition (t-0); (ii) two days before (t-1; t-3); and (iii) two days after (t-2; t-4) of the first and second competitions. Morphological measurements (body mass, percentage of total body fat and height), blood pressure, power, and resting heart rate variability (RR with Polar band) were recorded before and after Wingate test at each time. Results: Body fat was higher in females compared to males. However, no differences were found in other morphological parameters. An intra-subject analysis grouped by sex in cardiovascular parameters shows longitudinal variations in systolic pressure and mean pressure among females. Additionally, females depicted higher, very low frequency (VLF, which is intrinsically generated by the heart and strongly associated with emotional stress) after physical fatigue compared to males at t-1. Further, before the competition, the high frequency (HF) component of HRV (parasympathetic drive) was higher in males than females at t-0 and t-4. Conclusion: Our data revealed that males displayed greater parasympathetic reactivity after an anaerobic muscle fatigue test during their competition periods. Contrarily, females had a less cardiac autonomic modulation when comparing the pre-post Wingate test after two consecutive competition periods.

Kinematic and Neuromuscular Measures of Intensity During Drop Jumps in Female Volleyball Players.

The aim of this study was to assess drop jump (DJ) performance variables (jump height, contact time, and reactive strength index) concomitant to surface electromyography (sEMG) of lower limb muscles during DJs from different drop heights (intensities). The eccentric and concentric phase sEMG from the gastrocnemius medialis, biceps femoris, and vastus medialis muscles were assessed during all tests, with sEMG activity normalized to maximal voluntary isometric contraction (MVIC). In a cross-sectional, study, 10 amateur female volleyball players (age 22.1 ± 1.8 years; body mass 72.9 ± 15.2 kg; height 1.70 ± 0.08 m) completed DJs from six heights [15-90 cm (DJ15 to DJ90)]. During DJs there was no jump-target box to rebound on to. Results of one-way analysis of variance (ANOVA) showed that the jump height, contact time, and reactive strength index were not significantly (p > 0.05) different between drop heights. Mean biceps femoris eccentric and concentric sEMG ranged from 27 to 50%, although without significant differences between drop heights. Mean gastrocnemius medialis eccentric and concentric sEMG remained relatively constant (∼60-80% MVIC) across DJs heights, although eccentric values reached 90-120% MVIC from DJ75 to DJ90. Mean variations of ∼50-100% MVIC for eccentric and ∼50-70% MVIC for concentric sEMG activations were observed in the vastus medialis across DJs heights. The biceps femoris eccentric/concentric sEMG ratio during DJ45 (i.e., 1.0) was lower (p = 0.03) compared to the ratio observed after DJ90 (i.e., 3.2). The gastrocnemius medialis and vastus medialis eccentric/concentric sEMG ratio were not significantly different between drop heights. In conclusion, jumping performance and most neuromuscular markers were not sensitive to DJ height (intensity) in amateur female volleyball athletes.

Effects of Olympic Combat Sports on Health-Related Quality of Life in Middle-Aged and Older People: A Systematic Review.

Olympic combat sports are unconventional physical activity strategies to train middle-aged and older people with and without health problems. This systematic review aimed to assess the available body of published peer-reviewed articles related to the effects of Olympic combat sports interventions (boxing, fencing, judo, karate, taekwondo, wrestling) on health-related quality of life in adults aged 45 and older. The search was carried out in five generic databases until July 2021 and the protocol was registered in PROSPERO (code: CRD42021244161). The PRISMA guidelines were followed and the Downs and Black checklist was used to assessed the methodological quality of the studies. After reviewing 1,151 records, only seven studies met the inclusion criteria, adding 212 participants (43.4% female) with a mean age of 63.7 years. Six studies (two with middle-aged participants and four with older people) provided data to calculate the effect size (ES) in the Olympic combat sports groups (No research that used taekwondo or wrestling as an intervention modality was found). Three studies reported beneficial changes with a small ES for the total score (d < 0.40) of the health-related quality of life. Two studies reported a beneficial change with a small ES (d = 0.49) and strong ES (d = 4.45) for physical health. One study reported improvements with a small ES for emotional (d = 0.23) and functional (d = 0.26) well-being. In conclusion, interventions based on Olympic combat sports produce beneficial effects with a small and moderate ES on health-related quality of life in male and female aged 45 and older who are healthy participants, participants with Parkinson's disease, and participants with breast cancer. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, PROSPERO: CRD42021244161.

Kinematic and Neuromuscular Measures of Intensity During Plyometric Jumps.

Andrade, DC, Manzo, O, Beltrán, AR, Álvarez, C, Del Rio, R, Toledo, C, Moran, J, and Ramirez-Campillo, R. Kinematic and neuromuscular measures of intensity during plyometric jumps. J Strength Cond Res 34(12): 3395-3402, 2020-The aim of this study was to assess jumping performance and neuromuscular activity in lower limb muscles after drop jumps (DJs) from different drop heights (intensity) and during continuous jumping (fatigue), using markers such as reactive strength, jump height, mechanical power and surface electromyography (sEMG). The eccentric (EC) and concentric (CON) sEMG from the medial gastrocnemius (MG), biceps femoris (BF), and rectus (R) muscles were assessed during all tests. In a cross-sectional, randomized study, 11 volleyball players (age 24.4 ± 3.2 years) completed 20-90-cm (DJ20 to DJ90) DJs and a 60-second continuous jump test. A 1-way analysis of variance test was used for comparisons, with Sidak post hoc. The α level was <0.05. Reactive strength was greater for DJ40 compared with DJ90 (p ≤ 0.05; effect size (ES): 1.27). In addition, jump height was greater for DJ40 and DJ60 compared with DJ20 (p ≤ 0.05; ES: 1.26 and 1.27, respectively). No clear pattern of neuromuscular activity appeared during DJ20 to DJ90: some muscles showed greater, lower, or no change with increasing heights for both agonist and antagonist muscles, as well as for EC and CON activity. Mechanical power, but not reactive strength, was reduced in the 60-second jump test (p ≤ 0.05; ES: 3.46). No changes were observed in sEMG for any muscle during the EC phase nor for the R muscle during the CON phase of the 60-second jump test. However, for both MG and BF, CON sEMG was reduced during the 60-second jump test (p ≤ 0.05; ES: 5.10 and 4.61, respectively). In conclusion, jumping performance and neuromuscular markers are sensitive to DJ height (intensity), although not in a clear dose-response fashion. In addition, markers such as mechanical power and sEMG are, especially sensitive to the effects of continuous jumping (fatigue). Therefore, increasing the drop height during DJ does not ensure a greater training intensity and a combination of different drop heights may be required to elicit adaptations.

Effects of Plyometric Training on Explosive and Endurance Performance at Sea Level and at High Altitude.

Plyometric training performed at sea level enhance explosive and endurance performance at sea level. However, its effects on explosive and endurance performance at high altitude had not been studied. Therefore, the aim of this study was to determine the effects of a sea level short-term (i.e., 4-week) plyometric training program on explosive and endurance performance at sea level and at high altitude (i.e., 3,270 m above sea level). Participants were randomly assigned to a control group (n = 12) and a plyometric training group (n = 11). Neuromuscular (reactive strength index - RSI) and endurance (2-km time-trial; running economy [RE]; maximal oxygen uptake - VO2max) measurements were performed at sea level before, at sea level after intervention (SL +4 week), and at high altitude 24-h post SL +4 week. The ANOVA revealed that at SL +4 week the VO2max was not significantly changed in any group, although RE, RSI and 2-km time trial were significantly (p < 0.05) improved in the plyometric training group. After training, when both groups were exposed to high altitude, participants from the plyometric training group showed a greater RSI (p < 0.05) and were able to maintain their 2-km time trial (11.3 ± 0.5 min vs. 10.7 ± 0.6 min) compared to their pre-training sea level performance. In contrast, the control group showed no improvement in RSI, with a worse 2-km time trial performance (10.3 ± 0.8 min vs. 9.02 ± 0.64 min; p < 0.05; ES = 0.13). Moreover, after training, both at sea level and at high altitude the plyometric training group demonstrated a greater (p < 0.05) RSI and 2-km time trial performance compared to the control group. The oxygen saturation was significantly decreased after acute exposure to high altitude in the two groups (p < 0.05). These results confirm the beneficial effects of sea level short-term plyometric training on explosive and endurance performance at sea level. Moreover, current results indicates that plyometric training may also be of value for endurance athletes performing after an acute exposure to high altitude.

Effects of Exercise Training under Hyperbaric Oxygen on Oxidative Stress Markers and Endurance Performance in Young Soccer Players: A Pilot Study.

The aim of the present study was to determine the effects of three weeks of hyperbaric oxygen (HBO2) training on oxidative stress markers and endurance performance in young soccer players. Participants (18.6 ± 1.6 years) were randomized into hyperbaric-hyperoxic (HH) training (n = 6) and normobaric normoxic (NN) training (n = 6) groups. Immediately before and after the 5th, 10th, and 15th training sessions, plasma oxidative stress markers (lipid hydroperoxides and uric acid), plasma antioxidant capacity (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid [TROLOX]), arterial blood gases, acid-base balance, bases excess (BE), and blood lactate analyses were performed. Before and after intervention, maximal oxygen uptake (VO2max) and peak power output (PPO) were determined. Neither HH nor NN experienced significant changes on oxidative stress markers or antioxidant capacity during intervention. VO2max and PPO were improved (moderate effect size) after HH training. The results suggest that HBO2 endurance training does not increase oxidative stress markers and improves endurance performance in young soccer players. Our findings warrant future investigation to corroborate that HBO2 endurance training could be a potential training approach for highly competitive young soccer players.

Hydration status after exercise affect resting metabolic rate and heart rate variability.

INTRODUCTION: Heart rate variability and resting metabolic rate are commonly to assess athlete's physiological status and energy requirements. Exercise-induced dehydration can reach up to 5% of body mass per hour. Consequently, dehydration may have a profound physiological effect on human's homeostasis. OBJECTIVES: To compare the effects of dehydration and rehydration after exercise on heart rate variability and resting metabolic rate in college athletes. METHODS: 14 college athletes were divided into a dehydration group (n=7) and a rehydration group (n=7), both submitted to basal (T1) heart rate variability and resting metabolic rate measurements. After basal measurements both groups were actively dehydrated (-3.4 ± 0.4% of body mass for both groups). Afterwards, dehydration group rested, while rehydration group receive a fluid intake (during a 3 h period) equivalent to 150% of body mass loss achieved during active dehydration. Four hours after active dehydration heart rate variability and resting metabolic rate were re-assessed (T2). RESULTS: At T2 both rehydration group (+13%) and dehydration group (+30%) achieve a significant (p<0.05) increase in resting metabolic rate, however, only dehydration group ..showed a significant reduction in heart rate variability. More so, the change in resting metabolic rate was significantly higher in dehydration group compared to rehydration group. DISCUSSION: Hydric homeostasis after exercise affects resting metabolic rate and heart rate variability, highlighting the necessity to control hydration state before resting metabolic rate and heart rate variability assessment.

Introducción: La variabilidad del ritmo cardiaco y la tasa metabólica basal se utilizan en evaluaciones de deportistas. La deshidratación por ejercicio puede conducir a pérdidas de hasta 5% de la masa corporal. En consecuencia, la deshidratación produce un profundo efecto sobre la homeostasis humana. Objetivos: Comparar los efectos de la deshidratación y la rehidratación después del ejercicio en la variabilidad del ritmo cardíaco y la tasa metabólica basal. Métodos: 14 atletas universitarios fueron divididos en un grupo de deshidratación (n=7) y un grupo de rehidratación (n=7), ambos fueron sometidos mediciones basales (Tiempo 1) de variabilidad del ritmo cardíaco y tasa metabólica basal. Después de las mediciones basales, ambos grupos se deshidrataron activamente (-3,4 ± 0,4% masa corporal). Posteriormente, el grupo de deshidratación descansado, mientras que el grupo de rehidratación recibió agua equivalente al 150% de la masa pérdida. Cuatro horas después de la deshidratación se re-evaluó la variabilidad del ritmo cardíaco y tasa metabólica (Tiempo 2). Resultados: El grupo de rehidratación (+13%) y el de deshidratación (+30%) lograron un aumento significativo en la tasa metabólica basal (p.

Análise bibliométrica da pesquisa na América do Sul em ciências do esporte 1970-2012 / Análisis bibliométrico de la investigación en América del Sur en las ciencias del deporte 1970-2012 / Bibliometric analysis of South American research in sports science from 1970 to 2012

Sports science article publication in South American countries (n=11) was studied between 1970-2012, using all citation database of ISI Web of Knowledge. We evaluated: number of published articles; the number of publications divided by the number of people in science and technology (number pub/number peo); the top incidence of research subjects; public or private institutional predominance; impact factor (IF); average citations per document per country; and frequency of published articles per journals per country. Brazil showed the highest number of published articles, followed by Argentina. Bolivia showed the highest number pub/number peo, followed by Peru. Most studied themes were physiology, orthopedic and rehabilitation. Public institutions showed a higher published articles number than did private institutions. Peru and Bolivia were the only countries with a mean IF of 2 or higher. Average citation was higher in Peru (higher coefficient variation). In conclusions, our results show that, in most South American countries, their published articles rate has increased over time. This could be related to new government and institutional policies. However, production was low compared with other areas of science.

Produção de artigos científicos do esporte em países da América do Sul (n = 11) foi estudada entre 1970-2012 utilizando: todos os dados de citações do ISI Web of Knowledge. Foram avaliados: número de artigos publicados; número de artigos publicados/número de pessoas em ciência e tecnologia (no.pub/no.pes); assuntos mais estudados; predominância de instituições publicas ou privadas; fator de impacto (FI); citações média por documento por país no ISIweb; frequência de artigos publicados por periódicos por país. Brasil teve o maior número de artigos publicados, seguido pela Argentina. Bolívia mostra o mais elevado no.pub/no.pes, seguido pela Peru. Os temas mais estudados foram: ortopedia, fisiologia e reabilitação. As instituições públicas que apresentam maior número de artigos publicados. Peru e Bolívia foram os únicos países com uma média IF de 2 ou superior. Citação média foi maior no Peru (maior coeficiente de variação). Nas conclusões, nossos resultados mostram que, na maioria dos países, a sua taxa de artigos publicados aumenta ao longo do tempo. Isso pode estar relacionado com o novo governo e políticas institucionais. No entanto, a produção foi baixa em comparação com outras áreas.

Se estudió la producción de artículos en ciencias del deporte en países de América del Sur (n=11) entre 1970-2012, usando: todas las bases de datos de citaciones de ISI Web Knowledge. Se evaluó: número de publicaciones de artículos; número de publicaciones de artículos / número de personas en ciencia y tecnología (no.pub/no.peo); temas más estudiados; predominancia de instituciones públicas y privadas; factor de impacto (IF); promedio de citas por documento por país; frecuencia de publicaciones de artículos por revista por país. Brasil tuvo más publicaciones de artículos, seguido de Argentina. Bolivia muestra el mayor no.pub/no.peo, seguido por Perú. Los temas más estudiados fueron fisiología, ortopedia y rehabilitación. Las instituciones públicas muestran un mayor número de publicaciones de artículos. Perú y Bolivia son los únicos países con una media de IF de 2 o mayor. El promedio de citaciones fue elevado en Perú (elevado coeficiente de variación). En conclusión, nuestros resultados muestran que en la mayoría de los países el rango de publicaciones de artículos se incrementó con el tiempo. Esto puede ser relacionado con nuevas políticas gubernamentales e institucionales. Sin embargo, la producción es baja comparado con otras áreas.

Efectos de una sesión de ejercicio aeróbico en la presión arterial de niños, adolescentes y adultos sanos / Effects of a single bout of aerobic exercise on body weight and blood pressure among healthy participants

Background: Physical inactivity is a major risk factor and aerobic exercise is protective for cardiovascular health. Aim: To determine the effects of aerobic exercise on systolic and diastolic blood pressure in children, adolescents and adults. Material and Methods: We studied 13 children aged 10 ± 1.9 years, 13 adolescents aged 14.3 ± 1.5 and 55 adults aged 41 ± 11.5 years. Participants completed 60 minutes of aerobic exercise in one session. Body weight, systolic and diastolic blood pressure, and resting heart rate were measured before and after the exercise period. Results: Adult men and women experienced a significant decrease in body weight after exercise (-8 and -6%, respectively). No significant changes in weight were observed in children and adolescents. After exercise systolic and diastolic blood pressure decreased significantly in children (-8.3 and -5.4% respectively), adolescents (-7.6 and -8.4% respectively) and adults (-7 and -5.1% respectively). Conclusions: A 60 minute period of aerobic exercise is associated with a reduction in blood pressure in children, adolescents and adults.

[Effects of a single bout of aerobic exercise on body weight and blood pressure among healthy participants]. / Efectos de una sesión de ejercicio aeróbico en la presión arterial de niños, adolescentes y adultos sanos.

BACKGROUND: Physical inactivity is a major risk factor and aerobic exercise is protective for cardiovascular health. AIM: To determine the effects of aerobic exercise on systolic and diastolic blood pressure in children, adolescents and adults. MATERIAL AND METHODS: We studied 13 children aged 10 ± 1.9 years, 13 adolescents aged 14.3 ± 1.5 and 55 adults aged 41 ± 11.5 years. Participants completed 60 minutes of aerobic exercise in one session. Body weight, systolic and diastolic blood pressure, and resting heart rate were measured before and after the exercise period. RESULTS: Adult men and women experienced a significant decrease in body weight after exercise (-8 and -6%, respectively). No significant changes in weight were observed in children and adolescents. After exercise systolic and diastolic blood pressure decreased significantly in children (-8.3 and -5.4% respectively), adolescents (-7.6 and -8.4% respectively) and adults (-7 and -5.1% respectively). CONCLUSIONS: A 60 minute period of aerobic exercise is associated with a reduction in blood pressure in children, adolescents and adults.