Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 7 de 7
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Artigo em Inglês | MEDLINE | ID: mdl-31540105

RESUMO

The purpose of this study was to examine the associations of vitamin D status with athletic performance and blood-borne markers in adolescent athletes. This cross-sectional study included forty-seven Taekwondo athletes, aged 15-18 years old. Athletic performance was assessed using maximal oxygen consumption (VO2max), Wingate anaerobic power test, vertical jump, agility T-test, lower limb muscle strength, and fatigue resistance. Blood samples were collected to assess serum 25-hydroxyvitamin D [25(OH)D], free-testosterone, cortisol, creatine kinase, and urea. One-way ANOVAs were applied using Bonferroni adjusted alpha levels, which was 0.02 (i.e., 0.05/3). Multiple linear regressions analyses as well as Pearson and partial correlation analyses were used to examine the relationship among 25(OH)D concentration, athletic performance, and blood-borne markers. The participants 25(OH)D concentration were ranged from 16 to 73.25 nmol/L, indicating that 74.5% of the adolescent athletes have vitamin D insufficiency or deficiency. The vitamin D status did not show any significant effects on the performance factors or blood-borne markers. Serum 25(OH)D concentration was positively correlated with mean power output (r = 0.359, p < 0.05) and relative mean power output (r = 0.325, p < 0.05) after adjusting for bone age, height, weight, training experience, lean body mass, and fat mass. However, 25(OH)D concentration was not associated with other performance-related factors and blood-borne markers. In addition, multiple linear regressions analyses revealed that serum 25(OH)D concentration were not significant predictors of athletic performance in adolescent athletes. In conclusion, vitamin D status is weakly correlated with anaerobic capacity; moreover, the underlying mechanisms of how vitamin D influence anaerobic performance is unclear in the present study. Nevertheless, the importance of vitamin D on health benefits should not be underestimated, especially during growth periods.


Assuntos
Desempenho Atlético , Artes Marciais , Vitamina D/análogos & derivados , Vitaminas/sangue , Adolescente , Atletas , Biomarcadores/sangue , Creatina Quinase/sangue , Estudos Transversais , Humanos , Hidrocortisona/sangue , Masculino , Força Muscular , Consumo de Oxigênio , Testosterona/sangue , Ureia/sangue , Vitamina D/sangue
2.
Int J Sports Med ; 40(8): 503-510, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31288289

RESUMO

To examine the effect of high-intensity interval training (HIIT) with different work-to-rest ratios on athletic performance in athletes. Forty-seven male Taekwondo athletes (aged 15-18 yrs) were randomly assigned into 3 HIIT groups and a control group. Each group performed 6 and 8 bouts of HIIT: 1) 1:2 (30:60 s), 2) 1:4 (30:120 s), and 3) 1:8 (30:240 s) groups while the control group performed only Taekwondo training program. All HIIT groups completed 10 sessions over 4 weeks. Athletic performance tests including VO2max test, Wingate anaerobic test, vertical jump, and agility T-test were measured at both pre- and post-tests. Two-way repeated measures ANOVA were applied to examine the performance changes between protocols. VO2max improved significantly in all HIIT groups (p<0.01), and the post-hoc test indicated that the only 1:4 group showed significant improvement compared to the control group. The HIIT with 1:4 ratio showed the effective protocol for enhancing anaerobic capacity including relative peak and mean power compared to control (p<0.01). Ten sessions of HIIT involving the 1:4 group, lasting over a brief 4-week period revealed the effective protocol for enhancing both aerobic and anaerobic capacity. Our findings provide practical implications to develop a performance-enhancing program specialized for adolescent Taekwondo athletes.


Assuntos
Desempenho Atlético/fisiologia , Treinamento Intervalado de Alta Intensidade/métodos , Artes Marciais/fisiologia , Adolescente , Teste de Esforço/métodos , Frequência Cardíaca , Humanos , Masculino , Consumo de Oxigênio , Descanso
3.
Artigo em Inglês | MEDLINE | ID: mdl-30223447

RESUMO

Vitamin D insufficiency may be associated with increased risk of upper respiratory tract infection (URTI) in athletes. This study examined the effects of vitamin D3 supplementation on salivary immune functions and symptoms of URTI in vitamin D-insufficient taekwondo athletes. Twenty-five male taekwondo athletes, aged 19⁻22 years with vitamin D insufficiency [serum 25-hydroxyvitamin-D concentrations (25(OH)D, 31.3 ± 1.39 nmol/L)], participated in this study. They were randomized to receive 5000 IU/day of vitamin D3 (n = 13) or placebo capsule (n = 12) during 4 weeks of winter training. Blood samples were collected two times (pre- and post-tests) for analyzing serum 25(OH)D concentration while salivary samples were obtained three times (pre-, mid-, and post-tests) for secretory immunoglobulin A (SIgA) and lactoferrin analyses. The symptoms of URTI were reported daily during the intervention. Serum 25(OH)D concentration significantly increased by 255.6% in the vitamin D group, whereas in the placebo group it did not change (p < 0.001). While the significant increase in SIgA was observed in both groups (p < 0.001), elevated salivary lactoferrin level in response to winter training was found only in the placebo group (p = 0.011). The change in serum 25(OH)D concentration was negatively associated with total URTI symptoms (r = -0.435, p = 0.015). Vitamin D3 supplementation may be effective in reducing the symptoms of URTI during winter training in vitamin D-insufficient taekwondo athletes.


Assuntos
Colecalciferol/uso terapêutico , Artes Marciais/fisiologia , Infecções Respiratórias/prevenção & controle , Deficiência de Vitamina D/tratamento farmacológico , Atletas , Composição Corporal , Humanos , Lactoferrina/análise , Masculino , Saliva/química , Saliva/imunologia , Estações do Ano , Vitamina D/análogos & derivados , Vitamina D/sangue , Deficiência de Vitamina D/sangue , Vitaminas/uso terapêutico , Adulto Jovem
4.
Int J Sport Nutr Exerc Metab ; 28(6): 635-643, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29722590

RESUMO

We investigated the effects of vitamin D3 supplementation on physical performance during winter training in vitamin D insufficient taekwondo athletes. Thirty-five collegiate male and female taekwondo athletes, aged 19-22 years with low serum 25(OH)D concentration (28.8 ± 1.10 nmol/L), were randomly assigned to a vitamin D group (n = 20) or a placebo group (n = 15). Subjects received either a vitamin D3 capsule (5,000 IU/day) or a placebo during 4 weeks of winter training. Blood samples were collected for analyzing serum 25(OH)D concentration. Physical performance tests included Wingate anaerobic test, isokinetic muscle strength and endurance, a countermovement jump test, sit-ups, agility test, and 20-m pacer. Serum 25(OH)D concentrations increased significantly in the vitamin D group (96.0 ± 3.77 nmol/L) after 4 weeks of supplementation, but no changes were found in the placebo group (F = 242.44, p = .000). There were significant interaction effects for anaerobic peak power (F = 7.49, p = .010) and isokinetic knee extension at 180 deg/s (F = 6.08, p = .019). Changes in serum 25(OH)D concentration were positively associated with changes in peak power and isokinetic knee extension at 180 deg/s. However, no significant interaction effects were observed in other performance variables. This study suggests that 4 weeks of vitamin D supplementation elevates serum 25(OH)D concentration to sufficient levels. Correcting vitamin D insufficiency improves some but not all aspects of performance. Thus, efficacy of vitamin D supplementation to enhance performance remains unclear.


Assuntos
Colecalciferol/uso terapêutico , Suplementos Nutricionais , Artes Marciais , Deficiência de Vitamina D/tratamento farmacológico , Vitaminas/uso terapêutico , Atletas , Método Duplo-Cego , Teste de Esforço , Feminino , Humanos , Hidroxicolecalciferóis , Masculino , Força Muscular , Resistência Física , Estações do Ano , Adulto Jovem
5.
J Sports Med Phys Fitness ; 57(10): 1252-1260, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28085127

RESUMO

BACKGROUND: The purpose of this study was to determine the effects of high-intensity interval training (HIIT) on athletic performance in Taekwondo athletes. METHODS: Thirty-three male and female collegiate Taekwondo athletes were randomly divided into a HIIT group (N.=16) or a high-intensity continuous running (HICR) group (N.=17). The HIIT group undertook training of high-intensity sprints interspersed with active rest periods whilst the HICR group participated in high-intensity running for a continuous period. Both groups completed 11 sessions over 4 weeks. Physique, body composition, Wingate anaerobic test and VO2max test were measured. The vertical jump test, agility T-test and sit-ups were used to assess physical fitness. Repeated measures ANCOVAs with sex as a covariate were applied and significant level was set at 0.05. RESULTS: Following 11 sessions of training, significant improvements in anaerobic peak power (P<0.05), relative peak power (P<0.05), and mean power (P<0.05) were observed only in HIIT group compared to HICR group. A greater improvement of aerobic capacity was observed in HIIT group (8.8%) compared to the HICR group (1.7%). In relation to physical fitness, the HIIT group improved in the vertical jump while the HICR group did not change. Both the HIIT and HICR groups showed greater improvements in T-test and sit-ups during the intervention period. CONCLUSIONS: This study shows the effectiveness of eleven sessions of HIIT in producing significant improvements in anaerobic capacity relevant to successful Taekwondo competition performance in collegiate Taekwondo athletes. This could inform the future planning of Taekwondo athletes' pre-competition training, specifically the influence of training intensity on anaerobic capacity.


Assuntos
Desempenho Atlético/fisiologia , Treinamento Intervalado de Alta Intensidade/métodos , Artes Marciais/fisiologia , Aptidão Física/fisiologia , Corrida/fisiologia , Adolescente , Feminino , Humanos , Masculino , Consumo de Oxigênio/fisiologia , Distribuição Aleatória , Adulto Jovem
6.
J Exerc Rehabil ; 11(2): 101-7, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25960983

RESUMO

The purpose of the study was to determine the effect of 8 weeks pre-season training on body composition, physical fitness, anaerobic capacity, and isokinetic strength in collegiate taekwondo athletes. Thirty-four collegiate athletes (male: 22, female: 12) participated. Body composition, bone mineral density, physical fitness, anaerobic capacity, and isokinetic muscle strength were tested. After statistical analysis was performed the results indicated that there were significant decreases in body weight, percent body fat, and fat tissue after 8 weeks of pre-season training. Bone mineral density increased significantly only in males. There were significant improvements in the 50 m shuttle run and 20 m multistage endurance run in both males and females. The sit & reach test and standing long jump were not significantly changed after 8 weeks. Relative peak power and anaerobic capacity were significantly improved in males. Significant increases in angular velocity were observed for knee extension at both % BW 60°/sec and 180°/sec in both males and females. A significant increase in angular velocity was seen for right knee flexion at % BW 60°/sec for males, but it decreased at % BW 180°/sec for both males and females. In conclusion, this study suggests that 8 weeks of pre-season training has a positive effect on body composition, physical fitness, anaerobic capacity, isokinetic muscular strength, and endurance. Nevertheless, an exercise approach with the goal of increasing lean tissue, and improving power in knee flexors and flexibility of athletes, should be included in the training program.

7.
J Exerc Rehabil ; 11(6): 356-62, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26730387

RESUMO

This study compared nutritional intake, body composition, bone mineral density, and isokinetic strength by dance type in collegiate female dancers. The study subjects included Korean dancers (n=12), ballet dancers (n=13), contemporary dancers (n=8), and controls (n=12). Nutritional intake was estimated using the Computer Aided Nutritional Analysis Program. Body composition and bone mineral density were measured using dual-energy X-ray absorptiometry. Isokinetic knee joint strength was measured by Cybex 770-NORM. All statistical analyses were performed by SAS 9.2. Means and standard deviations were calculated using descriptive statistics. One-way analysis of variance was applied to evaluate nutritional intake, body composition, bone mineral density, and isokinetic strength differences. Duncan multiple range test was used for post hoc testing. A level of significance was set at P<0.05. The study results indicated no significant differences in nutritional in-take among dancer types. Despite no significant differences in body composition among dancer types, contemporary and ballet dancers had lower body fat percentages than controls (P<0.05). No significant differences were seen in bone mineral density and bone mineral contents among dancer types. No significant differences were found in isokinetic strength in right or left knee flexion and extension at 60°/sec (P<0.05). There were significant differences in body composition and isokinetic strength between dancer groups and the control group. Further studies of different professional dance type and more scientific methods of dance training are needed.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA