Glucose pulse. A simple method to estimate the amount of glucose oxidized during exercise in type 1 diabetic patients

In type 1 diabetic patients, exercise contributes to enhance insulin sensitivity and may help, together with diet and insulin therapy, to achieve and maintain better metabolic control. Fat and carbohydrates are the main substrates for energy production in skeletal muscle during aerobic exercise in well-fed humans, with their relative contribution to total energy production being a function of exercise intensity. Below the anaerobic threshold, both oxygen consumption and heart rate during exercise increase linearly as a function of exercise intensity. On the basis of these relationships, the aim of the present study was to verify the possibility of using heart rate to estimate the amount of glucose oxidized during exercise in type 1 diabetic patients as well as in a control group of healthy subjects. This study shows that heart rate can be a useful physiological parameter to be used to estimate the amount of glucose oxidized during exercise

Effetti del volo spaziale di lunga durata sulla funzionalita muscolare

Altérations structurelles et fonctionnelles du muscle en condition de microgravité simulée (par immersion)

Effetti del volo spaziale di lunga durata sulla funzionalita muscolare

Altérations structurelles et fonctionnelles du muscle en condition de microgravité simulée (par immersion)

Muscles in microgravity : from fibres to human motion

Modifications structurelles et fonctionnelles des fibres musculaires dues à la microgravité, chez l'homme. Propositions d'exercices musculaires pour l'entretien physique des astronautes en vol spatia

Muscles in microgravity: from fibres to human motion

In simulated or actual microgravity, human and animal postural muscles undergo substantial atrophy: after about 270 days, the muscle mass attains a constant value of about 70% of the initial one. Most animal studies reported preferential atrophy of slow twitch fibres whose mechanical properties change towards the fast type. However, in humans, at the end of a 42-days bed rest study, a similar atrophy of slow and fast fibres was observed. After microgravity, the maximal force of several muscle groups showed a substantial decrease (6–25% of pre-flight values). The maximal power during very short “explosive” efforts of 0.25–0.30 s showed an even greater fall, being reduced to 65% after 1 month and to 45% (of pre-flight values) after 6 months. The maximal power developed during 6–7 s “all-out” bouts on an isokinetic cycloergometer was reduced to a lesser extent, attaining about 75% of pre-flight values, regardless of the flight duration. In these same subjects, the muscle mass of the lower limbs declined by only 9–13%. Thus, a substantial fraction of the observed decreases of maximal power is probably due to a deterioration of the motor co-ordination brought about by the absence of gravity. To prevent this substantial decay of maximal absolute power, we propose that explosive exercise be added to the daily in-flight training schedule. We also describe a system aimed at reducing cardiovascular deconditioning wherein gravity is simulated by the centrifugal acceleration generated by the motion of two counter rotating bicycles ridden by the astronauts on the inner wall of a cylindrical space module. Finally, cycling on circular or elliptical tracks may be useful to reduce cardiovascular deconditioning in permanently manned lunar bases. Indeed, on the curved parts of the path, a cyclist generates an outward acceleration vector (ac). To counterbalance ac, the cyclist must lean inwards, so that the vectorial sum of ac plus the lunar gravity tends to the acceleration of gravity prevailing on Earth