Changes in muscle mass and force production after strength training based in contrast method (weight and light load) in people from 50 to 70 years old.

摘要

The amount of muscle mass and force production decreases as the age increases. Ageing implies a decrease in muscle mass as well as neural dysfunctions leading finally to a phase of functional dependence on other people. In the last decade strength training has been used as a way to avoid or reduce sarcopenia, a phenomenon by which a loss of muscle mass is related to ageing.;Strength training in elderly men and women leads both to maximal force increase and explosive force production, including nervous system as well as muscle hypertrophy improve. The increase of force production and muscle mass obtained through strength training reports profits in functional independence on other people and so an increase in their quality of life, therefore reducing the risk of contracting muscle and bone diseases.;The aim of our work is on one hand to examine the differences of muscular mass, force production, body fat percentage, haematology, blood biochemistry and urine analysis in 50--70 year old athletes and active subjects, both before and after the strength training and, on the other hand the effects of such a 16 week strength training on arm and thigh muscle CSA and on height jump in bosco protocol (SJ, CMJ, DJ and 15"CMJ) as well as the effects on body fat percentage, lean body mass, blood and urine.;The strength training is based on the alternative use of light and heavy leads.;A population sample of 22 subjects was studied which was divided into two groups (athletes n = 9- and active subjects n = 13-) and two test were performed, before and after strength training (independent variable). The dependent variables were maximum jumping height in Bosco protocol (SJ, CMJ, DJ and 15"CMJ measured with Ergojump Bosco system) body fat percentage (skinfold test and bioelectrical impedance), lean body mass (anthropometry), arm and thigh CSA (anthropometry) and blood and urine analysis.;The results suggested that the maximum jumping height in SJ, CMJ, DJ and 15"CMJ in higher in athletes than in active subjects of the same ages. Athletes and active subjects, likewise, have similar weight, arm and thigh CSA and lean body mass measured by Doupe et al.'s equation although the athletes group has a lower body fat percentage and a higher lean body mass as shown by the Martin et al.'s equation before the strength training.;A strength training based on heavy and light load contrast caused both groups to significantly improve their maximum jumping height, arm and thigh CSA, lean body mass and decrease their fat body percentage in the athletes group.;Neither significant changes were found in body weight for both groups nor in body fat percentage in the athletes group.;Blood and urine tests showed that there weren't any differences between both variables before the strength training, but red blood cells and MCV which are higher for the athletes group. After the strength training in all subjects, a significant decreases in the following parameters was found: CK, urea, and creatinine. A decrease in pH and basophiles percentage and increase in haemoglobin was found in the athletes group.;In the active subjects group it was found an increase in neutrophils percentage and a decrease in basophiles percentage, as well as significant traces of monocites and CK linked to a slight decreases in lymphocytes.