Ventilatory and occlusion-pressure responses to exercise in trained and untrained children.

Pattern of breathing and mouth occlusion pressure were investigated during an incremental and exhaustive ergocycle test in untrained and trained 11 to 13 year old boys. At each level of exercise, the trained group had lower ventilation, a lower respiratory equivalent, and a lower respiratory rate. These results suggest that trained subjects have more efficient ventilation. Lower ventilation coincided with a smaller mean inspiratory flow (VT/TI), while the ratio of inspiratory to total breath (TI/TTOT) was unchanged. In contrast, mouth occlusion pressure and the index of neuromuscular inspiratory drive were the same up to 60 W for the two groups, and tended to be slightly lower in the trained boys above this level.

Extent of lactic anaerobic metabolism in handballers.

The authors investigated lactic anaerobic metabolism in handball players during practice games. Seven players aged 18-21, belonging to second division league clubs, took part in the study. In the laboratory, VO2 max and the onset of blood lactate accumulation (OBLA) were determined with progressive maximal ergocycle tests. On the field, video recordings, cardiotelemetry, and rectal temperature measurements made during the first half of the game were used to quantify exertion. An intravenous catheter worn permanently was used to draw blood for lactate measurements at the 5th, 10th, 15th, 20th, and 30th min of play and after a 10-min rest period. The results confirmed earlier observations showing the need for an excellent maximal aerobic power and capacity in handballers. However, the maximal lactate levels observed (4-9 mmol X l-1) were above those that could be expected from samples drawn only at the end of play. These findings indicate that players must be trained to tolerate high lactate levels to preserve their maximal efficiency throughout the game. Finally, lactate production increased with player exertion and with increasing OBLA.

[Modalities of the hyperventilation of exercise in maximal triangular effort on the ergometry bicycle in 11-to-13-year-old boys]. / Modalités de l'hyperventilation d'exercice lors d'un effort triangulaire maximal sur bicyclette ergométrique chez des garçons de 11 à 13 ans.

Tidal volume, respiratory frequency, ventilatory equivalent, mean inspiratory flow Vt/Ti, and respiratory timing Ti/Ttot were measured at each level of an incremental exercise in a group of 8 untrained boys. Breathing pattern of the child is characterized by a fast frequency and a small tidal volume. Ventilation at maximal exercise reaches 50% of adults mean value. For the same ventilation, Vt/Ti (when expressed in ml X mn-1 X kg-1) is higher in the child. That suggests a higher central inspiratory activity.

[Comparative study of four effort tests on nine-year-old children. The value of systolic tension time (author's transl)]. / Etude comparative de quatre épreuves d'effort chez l'enfant de neuf ans. Intérêt du systolic tension time.

Simple effort tests were carried out on 9-year-old children to measure the systolic tension time (STT) and to judge the accuracy and limitations of such a test by comparing it with other measures more commonly employed in France for the same age group: Pachon-Martinet, Ruffier-Dickson, and maximal oxygen uptake (VO2max), the latter (estimated indirectly) serving as the standard of reference. Subjects stepped onto and off a stool 40 cm high, 24 times per minute; immediately thereafter the heart rate per minute and the arterial systolic pressure (mm Hg) were measured, and the product (the systolic tension time) was obtained. At the age of 9 years, 95% of children have an STT of between 13 000 and 25 000. This test, besides the ease with which it can be performed in daily experimentation, has the advantage of giving results that are at once more precise and more significant than the two standard tests of Pachon-Martinet and Ruffier-Dickson because the quality of the experiment is more satisfactory, because autonomic factors have less impact, and because its discriminative value is higher since only the STT provides a satisfactory correlation with VO2max. The test also fulfills the various requisites of an effort test: it can help to trace a poor cardiovascular response to effort and, because of its selective nature, it can also provide a convenient means of supervision of young athletes. In practice, the test should be complemented by a study of the first 3 min of recovery, as this was the only part of the test showing a difference between boys and girls, whether trained or not.