Observational study of potential risk factors of immersion pulmonary edema in healthy divers: exercise intensity is the main contributor.

BACKGROUND: The risk factors of pulmonary edema induced by diving in healthy subjects are not well known. The aim of the present study was to assess the parameters contributing to the increase in extravascular lung water after diving. METHODS: This study was carried out in a professional diving institute. All divers participating in the teaching program from June 2012 to June 2014 were included in the study. Extravascular lung water was assessed using the detection of ultrasound lung comets (ULC) by chest ultrasonography. Clinical parameters and dive profiles were recorded using a questionnaire and a dive computer. RESULTS: One-hundred six divers were investigated after 263 dives. They used an open-circuit umbilical supplying compressed gas diving apparatus in 202 cases and a self-contained underwater breathing apparatus in 61 cases. A generalized linear mixed model analysis was performed which demonstrated that the dive induced a significant increase in ULC score (incidence rate ratio: 3.16). It also identified that the predictive variable of increased extravascular lung water after the dive was the exercise intensity at depth (z = 3.99, p < 0.0001). The other parameters studied such as the water temperature, dive profile, hyperoxic exposure, or anthropometric data were not associated with the increase in extravascular lung water after the dive. CONCLUSIONS: In this study, the exercise intensity was the main contributor to the increase in extravascular lung water in healthy divers. To improve the prevention of immersion pulmonary edema, the exercise intensity experienced during the dive should thus be adapted to the aerobic fitness level of the divers.

Inter-limb changes in arterial function after intense cycling exercise.

We investigated whether muscle exercise, by inducing a subsequent local response, alters local and systemic arterial function differently. Eleven healthy volunteers (31±8 years) performed a 45-min cycling session at a heart rate corresponding to 10% above ventilatory threshold. Measurements were performed before and 45 min after exercise. Central and peripheral blood pressures were assessed by applanation tonometry and automatic sphygmomanometer, respectively. Brachial and popliteal arterial changes in diameter and blood flow were assessed using ultrasonography. The endothelium-dependent function was assessed simultaneously on brachial and popliteal arteries by flow-mediated dilation. Systolic blood pressure decreased significantly in both upper and lower limbs as well as centrally. Ankle-brachial index decreased significantly. Cross-sectional area and blood flow of popliteal and brachial arteries increased significantly. The increase in blood flow was higher in the brachial than in the popliteal artery, whereas diameter increase was of similar magnitude between the two arteries. When normalized with shear rate, brachial flow-mediated dilation was significantly greater, whereas popliteal flow-mediated dilation was similar post- vs. pre-exercise. After an acute bout of intense cycling, blood flow increase and endothelial function were greater in the non-exercised upper limb compared to the exercised lower limb, suggesting that anaerobic exercise blunts the enhancement of systemic endothelium-dependant vasodilation in active muscle beds.

Cardiac alterations induced by a fish-catching diving competition.

Cardiac changes induced by repeated breath-hold diving were investigated after a fish-catching diving competition. Eleven healthy subjects carried out repeated breath-hold dives at a mean maximal depth of 20 ± 2.7 msw (66 ± 9 fsw) during 5 h. One hour after the competition, the body mass loss was -1.7 ± 0.5 kg. Most of the breath-hold divers suffered from cold and although the core temperature remained normal, a decrease in cutaneous temperature was recorded in the extremities. Systolic blood pressure was reduced in both upper and lower limbs. Heart rate was unchanged, but left ventricular (LV) stroke volume was reduced leading to a decrease in cardiac output (-20%). Left atrial and LV diameters were significantly decreased. LV filling was assessed on a trans-mitral profile. An increase in the contribution of the atrial contraction to LV filling was observed. Right cavity diameters were increased. The cardiac autonomic alterations were in favor of sympathetic hyperactivity. After a fish-catching diving competition in cold water, alterations suggesting dehydration, contraction in plasma volume and sympathetic hyperactivity were observed. Furthermore, enlargements of right cavities were in favor of right ventricular strains. Repeated apnea and swimming in cold water may account for these alterations.

Ultrasound lung comets induced by repeated breath-hold diving, a study in underwater fishermen.

Pulmonary edema has been reported in breath-hold divers during fish-catching diving activity. The present study was designed to detect possible increases in extravascular lung water (EVLW) in underwater fishermen after a competition. Thirty healthy subjects were studied. They participated in two different 5-h fish-catching diving competitions: one organized in the winter (10 subjects) and one organized in the autumn (20 subjects). A questionnaire was used to record underwater activity and note respiratory problems. An increase in EVLW was investigated from the detection of ultrasound lung comets (ULC) by chest ultrasonography. Complementary investigations included echocardiography and pulmonary function testing. An increase in EVLW was detected in three out of 30 underwater fishermen after the competition. No signs of cardiovascular dysfunction were found in the entire population and in divers with an increase in the ULC score. Two divers with raised ULC presented respiratory disorders such as cough or shortness of breath. Impairment in spirometric parameters was recorded in these subjects. An increase in EVLW could be observed after a fish-catching diving competition in three out of 30 underwater fishermen. In two subjects, it was related to respiratory disorders and impairment in pulmonary flow.

Determinants of physical activity and physical and sports activities in French school children.

The influence of morphological, biological, sociological, psychological, and environmental factors on the practice of organized sports and the amount of moderate to vigorous physical activity was examined through a questionnaire and continuous heart-rate monitoring, for 80 schoolchildren, 11 to 16 years old. Sport-practicing boys had a lower percentage of fat mass. Sport-practicing girls had more frequently sport-practicing mothers and higher scores on achievement motivation than nonsport-practicing girls. Active boys had more frequently sport-practicing fathers than inactive boys. No statistically significant correlation was found between moderate to vigorous physical activity and organized sports. Those children who are the most involved in organized sports are thus not necessarily the most active ones.

Physical activity and sport involvement in French high school students.

The links between morphological, biological, sociological, psychological, and environmental characteristics, the practice of organized sports, and moderate to vigorous physical activities were examined by means of a questionnaire given to 48 high-school students aged between 16 and 19 years and their continuous heart-rate monitoring. Few correlations appear between these characteristics and moderate to vigorous physical activities. Only maximal oxygen uptake is linked to this type of activity in girls. Concerning sport involvement, correlations were more numerous for girls than boys. Physical and sports activities of girls were linked with maximal oxygen uptake, sport involvement of father, support, and encouragements of practice, perception of own activity, and private environment. Among boys, physical and sport activities were only linked with sport involvement of friends and perception of own activity. Unlike boys, physical and sport activities among girls seemed more strongly linked to sociological characteristics than other ones.

Influence of the menstrual cycle phase and menstrual symptoms on maximal anaerobic performance.

PURPOSE: This study was designed to analyze the effect of the menstrual cycle phase on maximal anaerobic performance during short-term anaerobic tests. METHODS: Seven eumenorrheic women (NOC) and 10 women using monophasic oral contraceptives (OC) performed three anaerobic tests (force-velocity, multi-jump, and squatting jump tests) during menstruation (M: between days 1 and 4), the midfollicular phase (F: between days 7 and 9), and the midluteal phase (L: between days 19 and 21) of the ovarian cycle. Follicular and luteal phases were confirmed by serum progesterone levels. The order of testing sessions was randomly assigned and a 15-min standardized warm-up preceded each testing session. Rectal temperatures were taken before (Trec(b)) and after (Trec(a)) warm-up. RESULTS: No significant differences were observed among M, F, and L in Trec(b), Trec(a) maximal cycling power (Pmax(c)), maximal jumping power (Pmax(j)), or maximal height of jump (h(j)) in either NOC or OC. Ten of the women suffered premenstrual or menstrual symptoms (MS); the other seven did not report any premenstrual or menstrual discomfort (NMS). Presence or absence of symptoms was not correlated with oral contraceptive use. No significant differences were observed among the three stages of the menstrual cycle in Pmax(c), Pmax(j), or h(j) in NMS. In MS, only Pmax(j) decreased by 8% in M compared with that in F (P < 0.05). CONCLUSIONS: Although there were no significant differences in maximal anaerobic performance during different menstrual cycle phases, results of this study suggest that the presence or absence of premenstrual or menstrual syndrome symptoms may have an effect, possibly through an action on the stretch-shortening cycle of tendons and ligaments.

Diurnal variations in ventilatory and cardiorespiratory responses to submaximal treadmill exercise in females.

Diurnal variations in ventilatory and cardiorespiratory responses to submaximal treadmill exercise were analysed in 11 eumenorrhoeic women and in 10 women using monophasic oral contraceptives. Subjects performed submaximal treadmill exercise at three intensities averaging 7, 8, and 9 km x h(-1), each for 4 min at 0800, 1300 and 1700 hours, assigned randomly on 3 separate days. Rectal temperature was measured before (T(rec(b))) and after (T(rec(a))) exercise. Cardiac frequency (f(c)), ventilation (V(E)), oxygen uptake (VO(2)), carbon dioxide output (VCO(2)), and respiratory exchange ratio (R) were assessed in the last minute of each stage of the exercise. Both T(rec(b)) and T(rec(a)) increased from 0800 to 1700 hours (P < 0.001). For a given submaximal work rate, VO(2) and VCO(2) were higher in the afternoon compared to the morning. Similarly, R was increased at 1700 hours compared to 0800 hours during the recovery period following exercise (P < 0.05). However, V(E) did not vary significantly during the day at any of the running intensities. No significant interactions (group x time of day) were observed in any of the studied parameters. In contrast to ventilation, the VO(2) and VCO(2) of the females during submaximal exercise were both affected by the time of day, without any differences between eumenorrhoeic women and users of oral contraceptives.

Continuous heart rate monitoring over 1 week in teenagers aged 11-16 years.

Heart rate (HR) was monitored in 66 French pubertal boys (B, n = 28) and girls (G, n = 38) aged 11-16 years to evaluate habitual physical activity (HPA) over a 1-week period in the winter. The HR and the percentage of heart rate reserve (%HRR) were taken to be indexes of the metabolic activity for the whole day and for the different parts of the day. The HPA was evaluated from the time spent each day below 50%HRR, between 50%-70%HRR and above 70%HRR, which related to the time spent in no or low physical activity (NLPA), moderate physical activity (MPA) and vigorous physical activity (VPA), respectively. No sex differences were observed in the average %HRR each day [%HRRmean, [B 30 (SD 4)%; G 32 (SD 4)%]] or in NLPA [B 715 (SD 61) min, G 711 (SD 81) min] and VPA [B 19 (SD 16) min, G 21 (SD 21) min] throughout the week. During school days, daily %HRRmean was 7% smaller in 14-16 year olds compared to 11-13 year olds. This was linked to a decrease in MPA and a concomitant increase in NLPA (P < 0.05). Daily %HRRmean varied significantly during the week (range: 28-34% HRR). There were significant differences among the periods of the day (P < 0.05). The HR was the greatest during physical education lessons [128 (SD 11) beats x min(-1)], recreation [113 (SD 15) beats x min(-1)] and lunch break [108 (SD 12) beats x min(-1)] and the lowest during the evening [94 (SD 10) beats x min(-1)]. It was only during the lunch breaks that %HRRmean was greater (P < 0.05) on school days than on free days. Of all the teenagers studied 32% were considered active during the week.

Time-of-day effects in maximal anaerobic leg exercise.

Time of day variations in maximal anaerobic leg exercise were studied in 23 men mean age 23 (SD 3) years. All the subjects performed two anaerobic tests (force-velocity and multi-jump tests) and those familiar with sprinting ran an additional 50-m dash (n = 16). The maximal anaerobic powers for cycling and jumping (Pcycling and Pjump) and maximal anaerobic velocity (vpeak) were performed consecutively in the same order for all tests. The force-velocity and force-power relationships were established to determine Pcycling. The flight time (tf) and the ground contact time (tc) were recorded from five consecutive jumps on a jump-ergometer to calculate Pjump. The vpeak was measured between the 35th and the 45th m during the dash-run. The test schedules were at 0900, 1400 and 1800 hours on separate days in random order. Rectal temperatures (Tre) and body mass (mb) were measured before each test. The Tre increased significantly from 0900 to 1800 hours (P < 0.001) but mb did not vary during the day (P > 0.05). The Pcycling and Pjump were higher at 1400 and 1800 hours than at 0900 hours. The differences between the morning and the afternoon reached 3% (P < 0.05) for Pcycling and 5%-7% for Pjump (P < 0.01). The time-of-day effect was significant for tf (P < 0.05) but not for tc. During the dash-run tests, the differences almost reached significance for vpeak between 0900 and 1800 hours (P = 0.0544). No significant variations were observed between 1400 and 1800 hours for cycling, jumping and running tests. A time-of-day effect in the maximal anaerobic power of cycle and multi-jump tests existed. Such variations would have pronounced effects when expressed in competitions.

Relationships between oxygen consumption and heart rate in transitory and steady states of exercise and during recovery: influence of type of exercise.

Relationships between percentage of maximal oxygen consumption (%VO2max) and percentage of maximal heart rate reserve (%f(cr)) were compared during steady states of exercise (S), transitory states of exercise (T) and a 5-min recovery period (R). Male adults [mean age 27 (SD 10) years] were studied exercising on a treadmill (TR, n = 26), cycle ergometer (CE, n = 14) and arm traction bench (ATB, n = 14). The exercise intensity was adjusted according to the subjects in order to reach exhaustion in 4-5 steps of 2 min (ATB) or 3 min (TR, CE). The 1st min of each stage was considered as T and the last minute of each stage as S. The oxygen consumption (VO2) and heart rate (f(c)) were recorded simultaneously. Significant correlations were observed for each type of exercise and for each state between %f(cr) and %VO2max (r range 0.87-1.00). During T and R, the %VO2max versus %f(cr) relationships were laterally shifted, suggesting a resetting of f(c) control mechanisms. In S, the intercept was greater than in T and R; in T, the slope was greater than in S and R. The VO2 could be predicted from individual %VO2max versus %f(cr) relationships during T and R as is usually done in S using specific equations. Taking into consideration the average relationships established on the three ergometers, the standard error of the predicted VO2 during S and T reached 10%-20% and 22%-38% in R. During exercise, the higher the intensity the better was the prediction of VO2 from f(c) (r range 0.46-0.60, P < 0.001). Therefore except at high exercise intensities, it was found that individual relationships had to be used to obtain an accurate estimation of VO2.

Evaluation of habitual physical activity from a week's heart rate monitoring in French school children.

Habitual physical activity (HPA) was studied in 30 boys and 34 girls aged 6-11 years. All the children performed a shuttle run test (SRT) to assess maximal heart frequency (fcmaxSRT) and to evaluate maximal oxygen uptake (VO2maxSRT). Heart rate (fc) was measured continuously from Monday to Sunday, using a heart rate counter. The time spent at fc greater than 140 beats. min-1 (tfc > 140) and at fc greater than 160 beats. min-1 (tfc > 160) permitted HPA to be evaluated. The daily heart rate (fcd) and the percentage of heart rate reserve (%fcrd) were calculated to evaluate the metabolic activity. In the boys and girls, fcd and % fcrd varied little with age. The metabolic activity varied in a rhythmical way during the week and was higher during school days than during free days (P < 0.001). The children were more active during school days (ds) than during the free days (df). This observation was particularly marked in the boys having tfc > 140 being twice as high during ds compared to df [tfc > 140, ds 85 (SD 25), df 40 (SD 26) min; tfc > 160, ds 36 (SD 19), df 16 (SD 13) min]. During ds tfc > 160 was greater in the boys than in the girls (P < 0.01). The same held for tfc > 140 and % fcrd from the age of 9 years (P < 0.001). It was during the recreation periods that the differences between the boys and the girls were observed (P < 0.01). There was no significant difference between the boys and the girls during lessons, in the evening and during df (% fcrd 26-28%, tfc > 140 35-45 min, tfc > 160 10-18 min). In contrast, the children who were physically active in a sports club, had less spontaneous physical activity and % fcrd, tfc > 140, tfc > 160 and VO2maxSRT were identical to those of the other children.