Impact of the national prevention policy and scrum law changes on the incidence of rugby-related catastrophic cervical spine injuries in French Rugby Union.

BACKGROUND AND AIMS: Catastrophic cervical spine injuries are rare in rugby union but require close monitoring. The aim of this study was to analyse the incidence of severe cervical spine injuries and determine the impact of a national prevention programme and new scrum rules implemented by the French Rugby Union. METHODS: A prospective study was performed between 2006 and 2013 including all players affiliated to the French Rugby Union. All cervical spine injuries resulting in death, tetraplegia or a permanent neurological deficit were included. Prevention programmes were implemented from 2007 to 2013 and a change in scrum rules in 2010. To measure the impact of rule changes, results between 2006-2010 and 2010-2013 were compared using a Poisson regression. RESULTS: Altogether, 31 injuries were observed and the mean annual incidence was 1.6 per 100 000 players. There were significantly more injuries in senior players compared to junior players (3.5 vs 0.6 per 100 000 players; CI 95% (2.1 to 4.9) vs (0.1 to 1.0)). Incidence decreased from 1.8 in 2006 to 1.0 per 100 000 players in 2013 (p<0.0001). After 2010, there were significantly fewer injuries during scrums (p=0.02). In contrast, there were significantly more injuries in backs during 2010-2013 compared to 2006-2010 (p=0.003). CONCLUSIONS: The incidence of catastrophic cervical spine injuries has declined in French Rugby Union. The implementation of specific prevention programmes and scrum law changes has notably resulted in a decrease in scrum injuries in forwards. This prospective study should be continued to monitor the future progression of injuries and adapt prevention programmes accordingly.

Hazards of hydrodensitometry.

The limitations of the two-component model of body composition have been investigated extensively in the past resulting in a clear message of violation of basic assumptions underlying its use. This strong message may or may not be appropriate, since hydrodensitometry is still used, in particular in sports sciences. The combination of novel information with previously described indicators should allow to confirm or reject the pretended violation of basic assumptions underlying the use of hydrodensitometry. Water content of adipose tissue (AT) and of AT free mass as opposed to fat and fat free mass, and bone density of separate bones was obtained from the Brussels Cadaver Analysis Study collection. Analysis of different studies indicated anomalies up to -12% fat but also suggests that the borderline between chemical and morphological interpretations becomes vague and the ad hoc terminology does not reflect reality. Predicted % body fat using different methods on the same individual ranges between 9.6% up to 21% of AT. Total body water of separate tissues suggests intra-and intervariability within tissues. Whole skeleton density and the separate bone density cannot support the two-component constancy (1.164 g/mL to 1.570 g/mL).

Comparison of fat oxidation during exercise in lean and obese pubertal boys: clinical implications.

OBJECTIVE: To examine fat oxidation rates during exercise in lean and obese pubescent children. DESIGN: A graded leg cycle ergometry test was performed by two groups of pubescent boys (13 lean: mean (SD) age 12.0 (0.5) years, body mass index (BMI) 18.56 (1.12) kg/m(2); 17 obese: mean (SD) age 12.1 (0.1) years, BMI 26.68 (3.37) kg/m(2); p<0.001). The first step of the test was fixed at 30 W and power was gradually increased by 20 W every 3.5 min. The mean ventilatory gas measurement was obtained during the last 30 s of each step for calculation of fat oxidation rate vs exercise intensity. RESULTS: At low intensity (0-30% of peak oxygen consumption) when fat-free mass is considered, the fat oxidation rate was identical for the two groups. At higher intensities (40%, 50% and 60% of peak oxygen consumption) the fat oxidation rate was significantly higher in lean boys than in obese boys. CONCLUSION: These results confirm that obese pubertal boys have fat-free mass decreased capacities to use fat during moderate exercise. The findings suggest that obese boys need to practise physical activity at a lower intensity than healthy boys to enhance lipolysis and diminish adipose tissue and the consequences of obesity.

[Treatment of pediatric obesity: effects on body composition and physical fitness]. / Prise en charge ambulatoire de l'obésité: effets sur la composition corporelle et la capacité aérobie.

AIMS: To assess the efficiency of an ambulatory weight management programme of pediatric obesity, including 1 gymnastic session per week, on body composition and physical fitness (max). SUBJECTS: Fifteen adolescents participated in the 9-month intervention. BMI and fitness and physical activity assessed by a questionnaire were evaluated at baseline, and after intervention. RESULTS: Prepubescent subjects (N=6): no significant change of BMI, body composition, nor max. Pubescent subjects: significant decrease of BMI, and z score BMI, and % fat mass, increase of fat free mass. Activity questionnaire: non-significant trend to decreased TV watching, significant increase in practice of physical activity during weekend. CONCLUSION: A modest increase in physical practice, included in the dietary-behavioural management of adolescent obesity, is able to improve overweight and physical fitness.

The influence of circadian rhythm on muscle activity and efficient force production during cycling at different pedal rates.

The aim of this study was to examine the pedal rate and chronobiological impacts on muscle activity pattern and propulsive force production during cycling. Ten male competitive cyclists performed at 06:00 and 18:00 h a submaximal exercise on a cycle ergometer at a power output which elicited 50% of their respective W(max). The exercise was divided into 4 periods lasting 5 min each during which subjects were requested to use different pedal rates (free pedal rate, 70, 90 and 120 rev min-1) in random order. The study demonstrated that, under high pedal rate, several muscles exhibited a phase advance of activity. These modifications of temporal organization of muscle activity were not sufficient to keep an identical propulsive torque pattern. Time to peak torque was delayed when pedal rate increased. The effects of circadian fluctuation on electromyographic activity were limited to a later M. rectus femoris burst end and shorter activity duration for M. tibialis anterior at 06:00 h. From the results of this study, it seems that the influence of pedal rate in the range of torque fluctuation would depend on time-of-day of testing. The decrease in torque fluctuation due to pedal rate increase is reinforced when testing in the early morning. Taking this specific variable into consideration, the chronobiological effect increases the impact of pedal rate variations.

The effect of pedal rate and time of day on the time to exhaustion from high-intensity exercise.

The aim of this study was to examine the supposed influence of pedal rate on the diurnal fluctuation of the time to exhaustion from high-intensity exercise. Eleven male cyclists performed three tests at 06:00 h and three at 18:00 h at a free pedal rate (FPR) and two imposed pedal rates (80% and 120% of the FPR). They performed the tests until exhaustion using a power output corresponding to 95% maximal power (Pmax). Time to exhaustion, rectal temperature, oxygen consumption (.VO2), M. quadriceps, vastus medialis, M. biceps femoris electromyographic Root Mean Square activity rise (RMS slope), and blood lactate concentration were measured. The mean time to exhaustion recorded at 18:00 h (270.6+/-104.8 sec) was greater than at 06:00 h (233.9+/-84.9 sec). The time to exhaustion was significantly greater when the pedal rate was imposed at 80% versus 120% FPR. The blood lactate concentration and absolute core temperature at the point of exhaustion were significantly higher during tests done at 18:00 h. There was no diurnal variation in core temperature increase, .VO2, and RMS slope. The time-of-day effect for every variable did not depend on pedal rate. Diurnal variations in maximal aerobic endurance cannot be explained by a change in aerobic metabolism or in muscular fatigue. The origin of the diurnal variation in the time to exhaustion is likely to lie in greater participation in anaerobic metabolism. Also, the influence of temperature on neuromuscular functioning as an explanation for the diurnal variation in performance cannot be excluded in this study. The hypothesis on the basis of which pedal rate would influence diurnal variations in time to exhaustion in cycling was not validated by this research.

Effect of pedal rate on diurnal variations in cardiorespiratory variables.

Recently, it was observed that the freely chosen pedal rate of elite cyclists was significantly lower at 06:00 than at 18:00 h, and that ankle kinematics during cycling exhibits diurnal variation. The modification of the pedaling technique and pedal rate observed throughout the day could be brought about to limit the effect of diurnal variation on physiological variables. Imposing a pedal rate should limit the subject's possibility of adaptation and clarify the influence of time of day on physiological variables. The purpose of this study was to determine whether diurnal variation in cardiorespiratory variables depends on pedal rate. Ten male cyclists performed a submaximal 15 min exercise on a cycle ergometer (50% Wmax). Five test sessions were performed at 06:00, 10:00, 14:00, 18:00, and 22:00 h. The exercise bout was divided into three equivalent 5 min periods during which different pedal rates were imposed (70 rev x min(-1), 90 rev x min(-1) and 120 rev x min(-1)). No significant diurnal variation was observed in heart rate and oxygen consumption, whatever the pedal rate. A significant diurnal variation was observed in minute ventilation (p=0.01). In addition, the amplitude of the diurnal variation in minute ventilation depended on pedal rate: the higher the pedal rate, the greater the amplitude of its diurnal variation (p=0.03). The increase of minute ventilation throughout the day is mainly due to variation in breath frequency (p=0.01)--the diurnal variation of tidal volume (all pedal rate conditions taken together) being non-significant--but the effect of pedal rate x time of day interaction on minute ventilation specific to the higher pedal rate conditions (p=0.03) can only be explained by the increase of tidal volume throughout the day. Even though an influence of pedal rate on diurnal rhythms in overall physiological variables was not also evidenced, high pedal rate should have been imposed when diurnal variations of physiological variables in cycling were studied.

Muscular fatigue.

Although everyone knows fatigue personally, it is a difficult concept to define. For muscular fatigue, one must know the aspect of performance affected. The most obvious demonstrations are decreased maximal force and slowed muscular answer. Fatigue can have a central origin, by reducing cognitive performance or lowering excitation of motoneurons. Various mediators are in question (serotonin, moduline, dopamine). The fatiguing muscular contractions are accompanied by reduced discharges of motoneurons. The neuromuscular junction does not seem to be in question. Cold reduces muscular power, whereas a hot environment limits exercise by a central mechanism, which starts the normal behavioural response to stop the exercise. Fatigue can also be the consequence of overtraining. In the periphery, the electric activity of the membrane's surface is the first possible sign of failure, which explains high-frequency fatigue: the accumulation of potassium outside the cell blocks the sodic channels to block the potentials of action or slow down their propagation. With fatigue, less calcium is released and limits the number of attached actin-myosin bridges connections of actin-myosin. The slowing down of the muscular answer represents a deterioration of the function of actin-myosin bridges. On the metabolic level, the most-often evoked changes are reduced pH and increased intracellular lactate level. However, these variations cannot all describe fatigue, since patients with Mc Ardle disease do not exhibit these variations but very quickly experience tiredness. In fact, an association of small metabolic intracellular variations could explain tiredness. The fast fibres are larger than slow fibres; their metabolic needs are higher and they are thus more sensitive to tiredness. The half time of recovery is within approximately 1 min: normal values of force and power are recovered after 5 to 10 min. During endurance activities, the limiting factors are glycogen reserves and levels of oxidative enzymes. On the whole, mechanisms of fatigue must be explored to completely understand the governing phenomena.

Circadian rhythms in two types of anaerobic cycle leg exercise: force-velocity and 30-s Wingate tests.

Previous studies investigating the impact of circadian rhythms on performance during anaerobic cycle leg exercise have yielded conflicting results. The purpose of the present investigation was firstly, to determine the effect of the time of day on anaerobic performance during a force-velocity test on a cycle ergometer (F-V) and the Wingate test and secondly, to relate any changes in anaerobic performance to the circadian rhythm in oral temperature. Nineteen subjects volunteered to take part in the study. In a balanced and randomized study design, subjects were measured for maximal power (P (max)) (force-velocity test), peak power (P (peak)) and mean power (P (mean)) (Wingate test) on six separate occasions. These were at 02 : 00, 06 : 00, 10 : 00, 14 : 00, 18 : 00 and 22 : 00 hours on separate days. There was an interval of 28 h between two successive tests. Oral temperature and body mass were measured before each test. Body mass did not vary during the day but a significant time of day effect was observed for the oral temperature with an acrophase at 18 : 22 +/- 00 : 34 hours. A significant circadian rhythm was found for P (max) with an acrophase at 17 : 10 +/- 00 : 52 hours and an amplitude of 7 %. A time-of-day effect was significant for F (0) and V (0). Also a significant circadian rhythm was observed for P (peak) with an acrophase at 17 : 24 +/- 00 : 36 hours and an amplitude of 7.6 % and for P (mean) with an acrophase at 18 : 00 +/- 01 : 01 hours and an amplitude of 11.3 %. The results indicated that oral temperature, P (peak), P (mean) and P (max) varied concomitantly during the day. These results suggest that there was a circadian rhythm in anaerobic performance during cycle tests. The recording of oral temperature allows one to estimate the time of occurrence of maximal and minimal values in the circadian rhythm of anaerobic performance.

Diurnal variations in cycling kinematics.

Physiological and biomechanical constraints as well as their fluctuations throughout the day must be considered when studying determinant factors in the preferred pedaling rate of elite cyclists. The aim of this study was to monitor the diurnal variation of spontaneous pedaling rate and movement kinematics over the crank cycle. Twelve male competitive cyclists performed a submaximal exercise on a cycle ergometer for 15 min at 50% of their W(max). Two test sessions were performed at 06:00 and 18:00 h on two separate days to assess diurnal variation in the study variables. For each test session, the exercise bout was divided into three equivalent 5-min periods during which subjects were requested to use different pedal rates (spontaneous cadence, 70 and 90 rev min(-1)). Pedal rate and kinematics data (instantaneous pedal velocity and angle of the ankle) were collected. The results show a higher spontaneous pedal rate in the late afternoon than in the early morning (p < 0.001). For a given pedal rate condition, there was a less variation in pedal velocity during a crank cycle in the morning than in the late afternoon. Moreover, diurnal variations were observed in ankle mobility across the crank cycle, the mean plantar flexion observed throughout the crank cycle being greater in the 18:00 h test session (p < 0.001). These results suggest that muscular activation patterns during a cyclical movement could be under the influence of circadian fluctuations.

Circadian rhythms during cycling exercise and finger-tapping task.

The aim of this study was to follow the circadian fluctuation of the spontaneous pedal rate and the motor spontaneous tempo (MST) in a sample of highly trained cyclists. Ten subjects performed five test sessions at various times of day. During each test session, subjects were required to perform (i) a finger-tapping task, in order to set the MST and (ii) a submaximal exercise on a cycle ergometer for 15 min at 50% of their Wmax. For this exercise, pedal rate was freely chosen. Spontaneous pedal rate and heart rate (HR) were measured continuously. The results demonstrated a circadian variation for mean oral temperature, HR, and MST. Under submaximal exercise conditions, HR showed no significant time-of-day influence although spontaneous pedal rate changed significantly throughout the day. Circadian rhythm of oral temperature and pedal rate were strongly correlated. Moreover, a significant positive correlation was found between MST and pedal rate. Both parameters may be controlled by a common brain oscillator. MST, rest HR, and pedal rate changes follow the rhythm of internal temperature, which is considered to be the major marker in chronobiology, therefore, if there is a relation between MST and pedal rate, we cannot rule out partial dependence of both parameters on body temperature.

Colonic transit in soccer players.

To evaluate the effects of exercise on colonic function, we measured total and segmental transit times in 11 male soccer players and nine male radiology student technicians. Diet was kept constant in all subjects, who maintained their normal activities. For the soccer players, normal activities included 15 h of training and one match each week. Transit times were measured with radioopaque markers, using the multiple-ingestion, single-radiograph technique. No overall difference in large bowel transit was observed between the two groups. Right colon transit was considerably slower in the soccer players, whereas left colon and rectal transit were slightly accelerated. We conclude that an intensive sport activity only modifies regional differences in large bowel function. This may be of importance in extreme conditions, such as those experienced by marathon runners. Data should be obtained before prescribing exercise to treat constipation.

[Physiological variations of LpA1, HDL2 and principal lipid markers in athletes]. / Variations physiologiques de la LpA1, des HDL2 et des principaux marqueurs lipidiques chez l'homme sportif.

An original approach of the influence of physical activities on lipid metabolism is presented in this work: the authors studied the physiological variations of the lipoparticle LpA1, high-density lipoprotein subfraction HDL2 and the most important lipid markers in serum of a presumably healthy population of 55 high-level sportsmen. They were 18-45 years old and practised endurance sports, whether individual (cycling, long-distance running), or collective activities (soccer, basketball). The authors observed an important increase of LpA1 (+20%, p < 0.001) and C-HDL2 (+23.3%, p < 0.01) after an intense physical activity (CK = 430 +/- 312 U/l); they also found a good correlation between LpA1 and HDL2 (r = 0.85, p < 0.0001) and between LpA1 and CK (r = 0.62, p < 0.001).

[Nutrition of children and adolescents engaged in high-level sports activities]. / L'alimentation de l'enfant et de l'adolescent sportifs de haut niveau.

Young high-level athletes are frequently exposed to deficiencies, the most frequent origin of which is dietary. Supervision must be clinical, biological and dietary. Recommendations should be made individually, based on the nature and intensity of the exercise, and are calculated from the recommended supplements for the paediatric population. Protein, glucid and lipid supplements must represent approximately 12, 60 and 28% of the daily energetic intake respectively, the glucid ratio reaching 70% under certain conditions of prolonged exercise. Liquids must be controlled when exercise takes place in a warm atmosphere because young athletes are rapidly exposed to dehydration, the osmolarity of the selected drink being below 250 mosm/l. Mineral and vitamin supplementations are recommended. For minerals, perspiration losses may be associated with dietary deficiency. Possible vitamin deficiencies concern B1, B2, B6, B9, B12, C and D vitamins. The daily mineral supplements are estimated at 10 mg for iron, 5 mg for zinc and 1 mg for copper, and have to be prescribed in regular treatment after biological control.

[Comparison of the efficacy of verapamil and diltiazem in stable exercise angina. A double-blind and crossover study]. / Comparaison de l'efficacité du vérapamil et du diltiazem dans l'angor d'effort stable. Etude en double aveugle et en crossover.

Calcium channel blockers are now recommended for the treatment of stable angina but few studies have been carried out comparing the efficacy of verapamil and diltiazem in this indication. The short-term efficacy of these two drugs was compared in a double-blind crossover trial in 12 patients. The following protocol was used, 24 hour selection period followed by two crossover treatment periods versus double placebo. Exercise stress tests were performed 2 hours after the last dose at the end of each treatment period. Each patient underwent 3 stress tests: the first during the selection period whilst taking verapamil and diltiazem placebo (ET0), the second after the first treatment period at day 7 (ET1) and the third after the second treatment period at day 14 (ET2). A comparison of exercise capacity (ET0 to ET1 and ET2) showed improved effort tolerance and an increase in the ischaemic threshold with calcium blocker therapy. The duration of effort, the maximum sustained load, the rate-pressure product and the time to ST depression were all significantly increased. On the other hand, there were no significant changes in the percentage theoretical maximum heart rate attained, the heart rate at which ST depression occurred, the maximum ST depression and the incidence of angina. A comparison between ET1 and ET2 did not show any difference in the parameters of maximum effort or of the appearance of myocardial ischaemia. The comparison of exercise stress tests performed after treatment with verapamil and after diltiazem showed that the total duration of exercise, the maximum sustained load (in watts) and the rate-pressure product were identical.(ABSTRACT TRUNCATED AT 250 WORDS)

[Immediate or delayed angioplasty during the acute phase of myocardial infarction. Apropos of 118 cases]. / Angioplastie immédiate ou différée à la phase aiguë de l'infarctus du myocarde. A propos de 118 cas.

The results of immediate percutaneous transluminal coronary angioplasty (PTCA) (260 +/- 167 minutes after onset of pain and an average of 56 minutes after thrombolysis) and deferred PTCA (average 9.6 days, range 1 to 30 days after infarction) were compared in 118 consecutive patients with acute myocardial infarction. The overall primary success rate of PTCA was 82.2 per cent; it was higher in those patients undergoing deferred angioplasty (96% vs 78%; p less than 0.05). The primary success rate of immediate PTCA was related to the severity of the stenosis before dilatation: 75 per cent success in occluded compared to 84 per cent in suboccluded vessels (over 90% stenosis) and 100 per cent success in vessels with under 90 per cent stenosis. Eighty one per cent of failed angioplasties occurred in patients with occluded arteries, the majority being left anterior descending (LAD) arteries (71.4%). The incidence of restenosis was 13.4 per cent. This complication was diagnosed at coronary arteriography performed 40 days after PTCA in 1 case, 47 days after PTCA in another case and at the 6 month control in 11 cases. Reocclusion was observed in 21 patients (21.7% of immediate successes). The occlusion was diagnosed at the first control after an average of 8 days in 15 cases. The interval between the onset of pain and thrombolysis and dilatation was significantly longer in the group with reocclusion compared with patients without reocclusion (314 minutes vs 193 minutes for thrombolysis, p less than 0.01; and 356 minutes vs 204 minutes fort PTCA, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Short-term clinical and haemodynamic assessment of balloon aortic valvuloplasty in 30 elderly patients. Discrepancy between immediate and eighth-day haemodynamic values.

Recently, percutaneous aortic valvuloplasty has been considered as a possible palliative procedure in elderly patients with critical valvular stenosis in whom valve replacement is deferred or contra-indicated because of high operative risk. However, the demonstration of the efficacy of such a procedure is based on immediate post dilatation haemodynamic data and clinical improvement. The purpose of this study was to evaluate the haemodynamic consequences of this procedure on the eighth day after a post procedure haemodynamic control. Thirty consecutive patients (mean age 75 +/- 8.4 years) with long-standing aortic stenosis were treated at the time of cardiac catheterization with balloon dilatation. Of these 30 patients, 24 (mean age 76 +/- 8) underwent haemodynamic evaluation eight days after the procedure. Prevalvuloplasty examination revealed a mean aortic valve gradient (MAVG) of 82 +/- 19.9 mmHg, a mean thermodilution calculated cardiac output (CO) of 3.6 +/- 0.9 l min-1 and a mean aortic valve area (VA) of 0.37 +/- 0.14 cm2. Immediate postvalvuloplasty control showed a fall in MAVG to 44.5 +/- 16.7 mmHg (P less than or equal to 0.001), a decrease in CO to 3.3 +/- 1.4 l min-1 (NS) and an increase in VA to 0.60 +/- 0.35 cm2 (P less than or equal to 0.01). Eighth-day haemodynamic control revealed an increase in MAVG to 71 +/- 18.8 mmHg (P less than or equal to 0.001), an increase in CO to 4.1 +/- 1.3 l min-1 (P less than or equal to 0.001) and a decrease in VA down to 0.47 +/- 0.10 cm2 (P less than or equal to 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

[Respiratory manifestations of ankylosing spondylitis (50 cases)]. / Manifestations respiratoires de la spondylarthrite ankylosante (50 observations).

Fifty patients with ankylosing spondylitis underwent radiography of the chest. In addition, 2 of them had bronchography, 3 had computerized tomography (CT) of the chest, 9 had respiratory function tests and 8 head ventilation/perfusion study by the Xenon method. Seven thoracic images were questionably specific of spondylitis, showing plural symphysis, strips of atelectasis, pleural thickening, apical pulmonary sclerosis and opacities of the diaphragmatic hilum. CT proved valuable in 1 case to confirm pulmonary fibrosis and in 2 cases to reveal that pleural thickening was continuous with an opacity ensheathing the vertebral body. In 7 out of 9 cases the functional restrictive deficit was accompanied by normal or supranormal functional residual capacity and increased residual volume. In all patients explored by the Xenon method, there was apical-caudal inversion of the ventilation/perfusion ratio. These findings suggest 3 pathogenic hypotheses: mere sequelae of hypoventilation, specific lung tissue fibrosis, extension by continuity of the vertebra-ensheathing process to the subpleural spaces.

[Pleural involvement and functional effect of asbestosis in 380 exposed patients]. / Atteintes pleurales et retentissement fonctionnel de l'asbestose chez 380 sujets exposés.

A large number of pleural abnormalities was detected by radiological and functional monitoring of 380 persons (mean age: 47 years) working in an asbestos processing factory. There were 127 cases of parietal pleura thickening (after 22 1/2 years' exposure), 11 cases of pleural calcifications (after 26 years' exposure) and 29 cases of obliteration of the costophrenic angle. Fourteen images of pulmonary asbestosis were encountered, 7 of which were associated with pleural effusion; they occurred at a mean age of 50 years, after 22 years' exposure. Pleural lesions had a restrictive influence on respiratory function in 24% of the cases and were sometimes painful. Small airway obstruction was detected by flow-volume loops in 9% non-smokers with pleural thickening, which suggests that intra-radiological lung lesions exist in asbestosis.