Wearable near-infrared spectroscopy: reliability and sensitivity among different endurance cycling exercise intensities

The present study investigated the reliability and sensitivity of a wearable near-infrared spectroscopy (wNIRS) device in moderate and heavy exercise intensity domains. On three separate days, eleven males performed an incremental test to exhaustion, and in the following visits, four submaximal constant-load bouts (i.e., test and retest) were performed in the moderate-intensity domain (100 and 130 W) and heavy-intensity domain (160 and 190 W). The local tissue oxygen saturation index (SmO2) and pulmonary oxygen uptake (V̇O2) were measured continuously. The absolute SmO2 and V̇O2 values and the change (Δ) from the 3rd to 6th min of exercise were calculated. There was good reliability for SmO2 measurements, as indicated by the high intraclass correlation coefficient analysis (ICC ≥0.84 for all) and low coefficient of variation between the two trials (CV ≤4.1% for all). Steady-state responses were observed for SmO2 and V̇O2 from the 3rd to the 6th min in the two moderate-intensity bouts (P>0.05), whereas SmO2 decreased and V̇O2 increased from the 3rd to the 6th min in the two heavy-intensity bouts (P<0.05). Together, these findings suggested that the SmO2 measured with a wNIRS device is reliable and sensitive to track local metabolic changes provoked by slight increments in exercise intensity.

Effects of caffeine on central and peripheral fatigue following closed- and open-loop cycling exercises

We examined whether endurance performance and neuromuscular fatigue would be affected by caffeine ingestion during closed- and open-loop exercises. Nine cyclists performed a closed-loop (4,000-m cycling time trial) and an open-loop exercise (work rate fixed at mean power of the closed-loop trial) 60 min after ingesting caffeine (CAF, 5 mg/kg) or placebo (PLA, cellulose). Central and peripheral fatigue was quantified via pre- to post-exercise decrease in quadriceps voluntary activation and potentiated twitch force, respectively. Test sensitivity for detecting caffeine-induced improvements in exercise performance was calculated as the mean change in time divided by the error of measurement. Caffeine ingestion reduced the time of the closed-loop trial (PLA: 375.1±14.5 s vs CAF: 368.2±14.9 s, P=0.024) and increased exercise tolerance during the open-loop trial (PLA: 418.2±99.5 s vs CAF: 552.5±106.5 s, P=0.001), with similar calculated sensitivity indices (1.5, 90%CI: 0.7-2.9 vs 2.8, 90%CI: 1.9-5.1). The reduction in voluntary activation was more pronounced (P=0.019) in open- (-6.8±8.3%) than in closed-loop exercises (-1.9±4.4%), but there was no difference between open- and closed-loop exercises for the potentiated twitch force reduction (-25.6±12.8 vs -26.6±12.0%, P>0.05). Caffeine had no effect on central and peripheral fatigue development in either mode of exercise. In conclusion, caffeine improved endurance performance in both modes of exercise without influence on post-exercise central and peripheral fatigue, with the open-loop exercise imposing a greater challenge to central fatigue tolerance.

Frontal sinus size on facial plain radiographs

Introduction: Plain radiographs are still routinely used for diagnosis in dentistry. They allow the assessmentof anatomical structures and their variations, and the detection of abnormalities in the region assessed. Theaim of this research was to determine the width and height distances of the frontal sinus on posteroanteriorskull view of Brazilian subjects. Materials and methods: The sample was composed of 158 posteroanteriorfacial radiographs (Caldwell projection). It was measured the height and width of the frontal sinus, both sides,under a standardized protocol, using rules and a viewer box. The relationship between frontal sinus size andside of the face, and size and age were evaluated. Results: Thirteen radiographs were excluded (six of unilateralfrontal sinus, two agenesies, and five showing totally individualized chambers). The final sample studied was of145 subjects. The mean values obtained were a 68 mm for latero-lateral and 39 mm for superoinferior distances.In 39.3% cases both sides were approximately equal or had the left chamber larger than the right one. Therewas a significant correlation between width and height of frontal sinus (Spearman coefficient), however therewas no significant difference among the age groups studied (Kruskal-Wallis, p > 0,05). Conclusion: There is agreat anatomical variety of frontal sinus in this population. The left cavity of frontal sinus is larger or equal tothe right one and the age group differences was not significant regarding the size of the frontal sinus.