Jerri Luiz Ribeiro

Effective force and economy of triathletes and cyclists.

The effective force applied on the crank, the index of pedalling effectiveness, and the economy of movement at 60, 75, 90, and 105 rev/min cadences were examined in nine cyclists and eight triathletes. Tests were performed on two days. Maximal oxygen uptake was measured and the second ventilatory threshold was estimated on day 1 using a stationary bicycle. On day 2, the four different cadences were tested at about 5% below the second ventilatory threshold. A strain gauge instrumented clip-less pedal mounted on the bicycle enabled us to measure the normal and tangential forces exerted on the pedal, while the pedal and crank angles were monitored with the aid of a video system. Based on this information, the effective force and the index of pedalling effectiveness were calculated. Cyclists produced significantly more effective force and a higher index of pedalling effectiveness at 60 and 75 rev/min and were significantly more economic at all cadences than triathletes. The significant and positive correlation between effective force and economy at all cadences suggests that improvement of the effective force would reflect on economy.

Inflammatory markers, endothelial function and cardiovascular risk

The need to study cardiovascular diseases (CVD) has become more and more relevant as their prevalence has increased over the years. An intact endothelial wall is essential to vascular health. Certain factors are responsible for maintaining this tissue intact, including nitric oxide (NO), which provokes dilation of blood vessels in response to shear stress. Expression of the endothelial nitric oxide synthase (eNOS) enzyme, which produces nitric oxide in response to increases in blood flow, is of fundamental importance to maintenance of the vascular system. When this enzyme is inhibited, nitric oxide production is reduced, causing endothelial dysfunction. Since C-reactive protein inhibits production of nitric oxide by the eNOS enzyme, it is one of the causes of endothelial dysfunction and cardiovascular events. The objective of the present study was to review scientific articles in the literature related to the subject ‘inflammatory markers and endothelial function’. A wide-ranging review of the current literature was conducted, using systematic analysis of bibliographic references indexed in PubMed, Scielo, Medline and LILACS database, for the years 1992 to 2013. The studies reviewed show that increases in inflammation causes reductions in NO and increases in cardiovascular events. Increased inflammation is associated with higher incidence of cardiovascular diseases.

Níveis de beta-endorfina em resposta ao exercício e no sobretreinamento

O sobretreinamento (ST) e um fenomeno esportivo complexo e multifatorial; e atualmente nao existe nenhum marcador independente que possa diagnostica-lo. Interessantemente, alguns sintomas do ST apresentam relacao com os efeitos da b-endorfina (b-end1-31). Alguns de seus efeitos sao importantes para o treinamento, como analgesia, maior tolerância ao lactato e euforia do exercicio. Esses efeitos podem ser revertidos por destreinamento ou por ST, ocasionando diminuicao no desempenho, reducao da tolerância a carga e depressao. O exercicio fisico e o principal estimulo da b-end1-31, pois sua secrecao e volume/intensidade dependente, tanto para exercicios aerobios quanto anaerobios. No entanto, o treinamento excessivo pode diminuir suas concentracoes, alterando assim seus efeitos beneficos para o treinamento. Portanto, a b-end1-31 poderia ser utilizada como um marcador adicional de ST, principalmente porque seus efeitos apresentam extensa relacao com os sintomas do ST.

Comparação de respostas fisiológicas absolutas e relativas entre ciclistas e triatletas

BASES AND OBJECTIVE: The ventilatory threshold (VT) has been used as an indicator of the lactate threshold and used as a reference for endurance training. The purpose of this study was to compare the maximal oxygen uptake (VO2MAX) and the VT during a bicycle ergometer test between cyclists and triathletes. METHODS: VO2MAX was determined by open-circuit spirometry in 12 cyclists and 13 triathletes. The ventilatory equivalent for oxygen consumption, the ventilatory equivalent for carbon dioxide production, partial pressure of oxygen and the partial pressure of carbon dioxide (PETCO2) were plotted in function of the workload. The criterion to determinate the VT was when the ventilatories equivalents increased with a concomitant reduction in the PETCO2. RESULTS AND CONCLUSIONS: There was difference (p < 0.05) for the VO2MAX (57.72 ± 3.92 and 49.47 ± 5.96 kg·ml-1·min-1), VO2 at VT (46,91 ± 5,96 and 42,16 ± 4,97 kg·ml-1·min-1), and maximal heart rate (FCMAX) (188.83 ± 12.89 and 174.61 ± 13.79 bpm) between cyclists and triathletes, respectively. Therefore, there was no difference for the %VO2MAX (81.42 ± 7.61 and 85.18 ± 6.87%), the heart rate at VT (168.5 ± 13.79 and 157.23 ± 16.15 bpm), as well as for the %FCMAX at which VT occurred in these athletes (89.23 ± 6.98 and 90.05 ± 1.04%). In conclusion, cyclists and triathletes showed different aerobic capacity because they had unlike physiological adaptations.

Sobretreinamento: teorias, diagnóstico e marcadores

The aim of the sports training is the increase and the improvement of the physical performance. Whenever the intensity, duration and the daily working load are not appropriate, positive physiological adaptations occur. However, there is a fairly subtle delimitation between an outstanding performance and a decrease in it due to overtraining. Overtraining may include: lesion and muscular weakness; cytosine activation; hormonal and hematological alterations; mood swings; psychological depression and nutritional problems which may lead to loss appetite and diarrhea. Several studies about overtraining have been conducted with the effort to identify its causes, symptoms, hypotheses, besides the markers that could identify it. Nevertheless, its diagnosis is very difficult since the overtraining symptoms are similar to the ones from pre-overtraining and to the ones from normal training, making it difficult to dissociate them. Currently, there is not a single marker that could predict overtraining, thus, the decrease in physical performance is still considered the gold-standard. Hormonal, biochemical, immune and psychological markers, besides the oxidative stress, may provide relevant information for an accurate and trustworthy diagnosis on overtraining.

Overtraining: theories, diagnosis and markers

The aim of the sports training is the increase and the improvement of the physical performance. Whenever the intensity, duration and the daily working load are not appropriate, positive physiological adaptations occur. However, there is a fairly subtle delimitation between an outstanding performance and a decrease in it due to overtraining. Overtraining may include: lesion and muscular weakness; cytosine activation; hormonal and hematological alterations; mood swings; psychological depression and nutritional problems which may lead to loss appetite and diarrhea. Several studies about overtraining have been conducted with the effort to identify its causes, symptoms, hypotheses, besides the markers that could identify it. Nevertheless, its diagnosis is very difficult since the overtraining symptoms are similar to the ones from pre-overtraining and to the ones from normal training, making it difficult to dissociate them. Currently, there is not a single marker that could predict overtraining, thus, the decrease in physical performance is still considered the gold-standard. Hormonal, biochemical, immune and psychological markers, besides the oxidative stress, may provide relevant information for an accurate and trustworthy diagnosis on overtraining.

Efeitos do exercício e do treinamento físico na hemostasia

O estado hipercoagulante pos-exercicio tem sido bem demonstrado, pois aumentos na atividade coagulante sao frequentemente registrados apos diversos protocolos de exercicio. Um dos efeitos agudos do exercicio mais consistente e o aumento da atividade coagulante refletido pelo aumento da atividade do FVIII, dos marcadores TAT e F1+2. Esse aumento e intensidade dependente. Quanto aos efeitos cronicos, a atividade coagulante de repouso nao se modifica com o treinamento. Os niveis de FVIII pos-exercicio, entretanto, sao maiores em sedentarios do que em treinados e os niveis de repouso de pacientes pos-infarto diminuem com o treinamento. A hiperfibrinolise provocada pelo exercicio tambem esta comprovada e, assim como a atividade coagulante, parece depender da intensidade. Foram registrados aumentos dos niveis de t-PA, u-PA, plasminogenio e diminuicao dos niveis de PAI-1 apos o exercicio. Os niveis de repouso de t-PA de pessoas inativas e maior que em ativos e atletas. Alem disso, pacientes pos-infarto apresentaram diminuicao significativa dos niveis de PAI-1 apos periodo de reabilitacao fisica. Os dados mais controversos estao relacionados aos efeitos cronicos dos niveis de t-PA. Enquanto estudos demonstram niveis maiores de t-PA em treinados comparados a sedentarios, outros mostram o contrario. Resultados mais consistentes acerca dos efeitos do exercicio no processo hemostatico, incluindo atividades coagulante e fibrinolitica, ainda sao necessarios. Existe ainda carencia quanto aos efeitos cronicos do exercicio, tanto em relacao aos beneficios na saude quanto a influencia na performance de atletas.

Efeitos do consumo agudo de cafeína sobre parâmetros metabólicos e de desempenho em indivíduos do sexo masculino

O objetivo deste estudo foi avaliar o efeito do consumo agudo de cafeina sobre a oxidacao de lipideos e desempenho durante o exercicio aerobico. Foram avaliados 15 individuos do sexo masculino, com idade media de 22,3 ± 2,7 anos, que realizaram teste de cargas progressivas em esteira rolante para determinacao do consumo maximo de oxigenio (VO2max) e limiares ventilatorios (LV). Cada voluntario realizou tres testes submaximos na intensidade de 10% abaixo do segundo LV, sendo orientados a permanecer em exercicio ate a exaustao. Trinta minutos antes de cada teste submaximo, foram ingeridos 250ml de uma das bebidas compostas por: cafe com adocante (CAD), cafe com acucar (CA) e cafe descafeinado com adocante (CD). Durante o exercicio, os individuos foram monitorados pelo ergoespirometro e frequencimetro. A oxidacao de lipideos foi predita pelo quociente respiratorio (QR) durante o teste, e o desempenho foi verificado pelo tempo de exercicio. Para comparar os resultados de QR e tempo de exercicio entre os grupos, foi utilizado Anova fatorial, e considerou-se significância estatistica um valor de p < 0,05. A media de VO2max foi de 50,18 ± 9,9ml/kg/min. Com a ingestao de CAD, a media do QR foi de 0,98 ± 0,18 e o tempo medio em exercicio foi de 24,1 ± 17,04 minutos. Com a ingestao de CA, a media do QR foi de 0,96 ± 0,2 e o tempo medio em exercicio foi de 24,4 ± 17,8min. No teste com ingestao de CD, a media do QR foi de 1,01 ± 0,24 e a media do tempo em exercicio foi de 20,6 ± 9,7min. Nao houve diferenca significativa entre os testes nos valores do QR e nem tempo de exercicio (p = 0,697 e p = 0,598, respectivamente). A cafeina nao aumentou a oxidacao de lipideos nem o desempenho de individuos jovens do sexo masculino.

The Effect of ABO Blood Group on von Willebrand Response to Exercise

Individuals of O blood group have significantly lower plasma levels of either Factor VIII (FVIII) or the von Willebrand factor (vWF). Conversely, there is accumulating evidence that elevated FVIII—vWF levels may represent an important risk factor for ischemic heart and venous thromboembolic disease. In this study, individuals exercised for 20 minutes at 10% below the first ventilatory threshold (aerobic threshold), which corresponds to 48% of maximum oxygen uptake. People with non-O blood group show higher resting and postexercise vWF levels compared with those of O blood group, as evidenced by a lower maximal heart rate. The groups were compared using the ANOVA one-way test, and a P < 0.05 was considered statistically significant. These results could change the way in which exercise training is designed for both healthy and sick individuals because O group individuals could have a more thrombogenic response to exercise.

Acute response of peripheral CCr5 chemoreceptor and NK cells in individuals submitted to a single session of low-intensity strength exercise with blood flow restriction

The purpose of this study was to compare the peripheral expression of natural killers and CCR5 in a session of low‐intensity strength training with vascular occlusion and in high‐intensity training. Young males were randomized into session groups of a high‐intensity strength training (HI) and a session group of low‐intensity strength training with vascular occlusion (LI‐BFR). The exercise session consisted in knee extension and bicep curl in 80% 1RM (HI) and 30% 1RM (LI‐BFR) with equalized volumes. Blood collection was made before, immediately after and 24 h after each training session. Immunophenotyping was carried out through CD195+ (CCR5) e CD3‐CD16+CD56+ (NK) in peripheral blood and analysed by flow cytometry and presented in frequency (%). Peripheral frequency of NK cells showed no significant difference in LI‐BFR group in time effect, while a gradual reduction of NK cells was identified in HI group in before‐24 h postexercise and after‐24 h postexercise comparison. However, significant differences have been found in relative change of NK cells immediately after exercise between sessions. In addition, HI and LI‐BFR groups showed a significant reduction in the cells expressed CCR5 during 24 h postsession compared to the postsession, but CCR5 also differed when comparing before‐24 h after session in the HI group. No differences were observed amongst the groups. LIO induced CCR5 response similar to the HI session, while the NK cells remained in similar frequency during the studied moments in LI‐BFR, but not in HI group, suggesting that local hypoxia created by the blood flow restriction was able to prevent a change in the frequency of peripheral cells and a possible immunosuppression.