Effects of acute and chronic exercise on the osmotic stability of erythrocyte membrane of competitive swimmers.

This study aimed to evaluate the influence of acute and chronic exercise on erythrocyte membrane stability and various blood indices in a population consisting of five national-level male swimmers, over 18 weeks of training. The evaluations were made at the beginning and end of the 1st, 7th, 13th and 18th weeks, when volume and training intensity have changed. The effects manifested at the beginning of those weeks were considered due to chronic adaptations, while the effects observed at the end of the weeks were considered due to acute manifestations of the exercise load of that week. Acute changes resulting from the exercise comprised increases in creatine kinase activity (CK) and leukocyte count (Leu), and decrease in hematocrit (Ht) and mean corpuscular volume (MCV), at the end of the first week; increase in the activities of CK and lactate dehydrogenase (LDH), in the uric acid (UA) concentration and Leu count, at the end of the seventh week; increases in CK and LDH activities and in the mean corpuscular hemoglobin concentration (MCHC), at the end of the 13th week; and decrease in the value of the osmotic stability index 1/H50 and increases in the CK activity and platelets (Plt) count, at the end of the 18th week. Chronic changes due to training comprised increase in the values of 1/H50, CK, LDH, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), serum iron (Fe), MCV and Plt. Although acute training has resulted in decrease in the osmotic stability of erythrocytes, possibly associated with exacerbation of the oxidative processes during intense exercise, chronic training over 18 weeks resulted in increased osmotic stability of erythrocytes, possibly by modulation in the membrane cholesterol content by low and high density lipoproteins.

A influência da natação no desempenho do triathlon: implicações para o treinamento e competição / The influence of swimming performance in triathlon: implications for training and competition

O triathlon é um esporte que envolve três modalidades diferentes: a natação, o ciclismo e a corrida - cada uma delas contribui diferentemente para o desempenho do triatleta. Neste sentido, este trabalho buscou organizar os fatores que determinam o desempenho na natação e como isto pode ser aplicado no treinamento e competição dos triatletas. Para tanto, foi realizada busca de artigos relacionados à natação no triathlon, utilizando os seguintes termos: triathlon, triatleta, performance na natação e suas traduções para o inglês quando necessário. A partir disso, destaca-se a natação como a modalidade mais intensa durante um triathlon. Nas provas curtas do triathlon, a intensidade desta etapa parece ser superior ao limiar anaeróbio. O tempo final desta primeira etapa do triathlon parece correlacionar-se positivamente com o tempo final das provas curtas, o que não ocorre nas provas mais longas. Nas provas com distância short e olímpica, a estratégia adotada na etapa da natação parece influenciar diretamente no resultado final da prova. Assim, o planejamento das cargas de treinamento entre as três modalidades do triathlon deve levar em consideração a distância e o formato das provas disputadas para obtenção do sucesso.

Triathlon is a sport that involves three different exercise modes, swimming, cycling and running, each of which contributes differently to the triathlete's performance. The objective of the present study was to analyze the factors that determine performance in swimming and how this can be used in triathletes' training and competitions. We searched articles on triathlon swimming using the following keywords in Portuguese: "triathlon," "triatleta," "performance na natação," and their translations into English when necessary. Swimming is considered the most intense phase during a triathlon event. In short triathlon races, the intensity of this phase seems to be higher than the anaerobic threshold. The split time of this first phase seems to correlate positively with final time of the short races, which is not true for longer races. During the short and Olympic triathlon, the pacing strategy adopted at the swimming phase seems to directly influence the final outcome of the race. Thus, the planning of training loads within the three exercise modes of triathlon must take into consideration the distance and format of the races to achieve success.