Anaerobic contribution to the time to exhaustion at the minimal exercise intensity at which maximal oxygen uptake occurs in elite cyclists, kayakists and swimmers.

Using 23 elite male athletes (8 cyclists, 7 kayakists, and 8 swimmers), the contribution of the anaerobic energy system to the time to exhaustion (t(lim)) at the minimal exercise intensity (speed or power) at which maximal oxygen uptake (VO2max) occurs (IVO2max) was assessed by analysing the relationship between the t(lim) and the accumulated oxygen deficit (AOD). After 10-min warming up at 60% of VO2max, the exercise intensity was increased so that each subject reached his IVO2max in 30 s and then continued at that level until he was exhausted. Pre-tests included a continuous incremental test with 2 min steps for determining the IVO2max and a series of 5-min submaximal intensities to collect the data that would allow the estimation of the energy expenditure at IVO2max. The AOD for the t(lim) exercise was calculated as the difference between the above estimation and the accumulated oxygen uptake. The mean percentage value of energy expenditure covered by anaerobic metabolism was 15.2 [(SD 6)%, range 8.9-24.1] with significant differences between swimmers and kayakists (16.8% vs 11.5%, P < or = 0.05) and cyclists and kayakists (16.4% vs 11.5%, P < or = 0.05). Absolute AOD values ranged from 26.4 ml.kg-1 to 83.6 ml.kg-1 with a mean value of 45.9 (SD 18) ml.kg-1. Considering all the subjects, the t(lim) was found to have a positive and significant correlation with AOD (r = 0.62, P < or = 0.05), and a negative and significant correlation with VO2max (r = -0.46, P < or = 0.05). The data would suggest that the contribution of anaerobic processes during exercise performed at IVO2max should not be ignored when t(lim) is used as a supplementary parameter to evaluate specific adaptation of athletes.

[Anaphylaxis due to a sting by Argas reflexus (the pigeon tick) A case report]. / Anafilassi da puntura di Argas reflexus (zecca del piccione). Descrizione di un caso.

A case of anaphylactic shock caused by an Argas reflexus sting in a young woman with a history of recurrent undefined urticaria-angioedema syndrome, is reported. This tick is an ectoparasite which is found on pigeons who usually nest under the roofs of dwellings. The diagnosis was based on the history and through a dosage of IgE specific antibodies with RAST, using an extract of salivary gland of Argas reflexus. This ectoparasite was also found in the home and identified through the microscope. It is known to be the potential carrier of the Borrelia burgdorferi, which is the vector of Lyme disease. In our case Argas reflexus caused IgE-mediated reactions and therefore this hypothesis must be considered in the investigation of urticaria-angioedema syndrome or anaphylactic shock in patients who live in houses with pigeons' nests.

A new respiratory valve system for measuring oxygen uptake during swimming.

We describe a new respiratory valve system with minimal dead space, which allows measurement of ventilation and oxygen uptake during swimming. The device offers considerable advantages in efficiency and accuracy over current equipment, and can be used in conjunction either with a miniaturized telemetry system for oxygen uptake measurement or with a conventional system. The valve has a low airflow resistance, a small dead space (15 ml), and an electrically operating, closed-circuit pump to remove excess water from the expiratory tube. The external form and the buoyancy of the valve have been hydrostatically and hydrodynamically designed to reduce drag and to ensure a correct mass in the water. To obtain this result a very sophisticated material, carbon fibre, has been utilized. Our studies showed that this respiratory system is ideal for obtaining valid and reliable values of oxygen uptake during swimming, even at high speed and in endurance swimming tests.

Nedocromil sodium in the prevention of exercise-induced bronchospasm in athletes with asthma.

The aim of this study was to determine the efficacy of nedocromil sodium in the prevention of exercise-induced bronchospasm (EIB) in 13 top athletes affected by bronchial asthma. At a dose of 4 mg the drug significantly reduced the fall in FEV1 compared with placebo but not with respect to basal values. In 9 athletes, 4 mg nedocromil sodium produced a good protective effect and reduced the mean fall in FEV1 to 4% with respect to baseline values, while in the remaining 4 subjects, the protective effect was not satisfactory. In these 4 "non responders" 6 mg nedocromil was effective, and in 2 cases induced prolonged bronchodilatation. In conclusion, the effect of nedocromil sodium in the prevention of EIB may be dose-dependent in relation to the degree of bronchial hyperreactivity or to interference of other factors.

Congenital dislocation of the knee.

Congenital dislocations of the knee (CDK) are rare, occurring 40-80 times more rarely than congenital dislocation of the hip (CDH). In a multicentric study of the European Paediatric Orthopaedic Society, 56 cases of CDK were found in 46 babies. Many other malformations associated with CDK were noticed, and muscular abnormality was always found at the knee. According to the classification of Leveuf, three grades have to be considered: grade 3, or complete dislocation, was the most frequent. At birth, treatment consisted of physiotherapy with rigid splint. Twenty-four patients with CDK have been treated only by the conservative technique. Operations were performed according to the abnormalities of the extensor apparatus: a progressive release and lengthening of the quadricipital tendon was necessary in all cases. In all forms of treatment, the range of the knee flexion was 120 degrees. Only two children had a bad result because of unstable knees. Results were always better with conservative treatment.

Comparison of different methods of leg lengthening.

Corticotomy according to Ilizarov was used for the treatment of congenital leg length discrepancies from June 1984 to June 1986. A comparison of the results of this method and previously performed methods has been made.

The effect of pre-stretch on mechanical efficiency of human skeletal muscle.

The mechanical efficiency of positive work was studied in six subjects performing three different types of exercises. On the first occasion the subjects ran on a motor-driven treadmill at 3.33 m s-1; the second and the third exercises consisted of performing rhythmical vertical jumps for 1 min both in rebound (RJ) and no-rebound (NRJ) conditions. The mechanical efficiency calculated in NRJ, which reflects only the conversion of biochemical energy into mechanical work, was found to be lower than the corresponding observation in RJ, 17.2 vs. 27.8% (P less than 0.001), respectively. These differences could not be explained by only the storage and recoil of elastic energy occurring in RJ compared with NRJ. The calculated extra work delivered 'free' was greater than the potential elastic energy which could be stored within the leg extensor muscles (187 vs. 124 J for each jump, P less than 0.05). It is likely that other factors might be responsible for the extra work found in NRJ. It was suggested that the difference in the length of time to perform positive work between a simple shortening contraction and a stretch-shortening muscular activity could be also responsible for the enhanced efficiency observed in RJ. This suggestion was supported by the high relationship (P less than 0.001) found between the time to perform positive work and the mechanical efficiency measured in jumping and estimated during running.

A critical review of the surgical treatment of congenital proximal radio-ulnar synostosis.

Twenty-two patients for a total of 26 synostoses submitted to surgical treatment at the Rizzoli Orthopaedic Institute were evaluated. Following a critical analysis of the results obtained with various methods of surgical correction, the authors propose what they believe to be the best types of treatment for this rare deformity.

Congenital proximal radio-ulnar synostosis: clinical and anatomical features.

A new radiographic classification is proposed based on a study of 31 cases of congenital proximal radio-ulnar synostosis in which close correlation was observed between the clinical and radiographic pictures. The authors attempt to clarify some aspects of the pathogenesis of this rare disease.

Tibial lengthening according to Ilizarov in congenital hypoplasia of the leg.

Thirteen patients with leg length discrepancy due to congenital tibial hypoplasia were treated by the Ilizarov lengthening method. Advantages and disadvantages as compared with the Wagner and Anderson methods are reported, as well as with complications and results.

Congenital pseudarthrosis of the fibula.

Three cases of congenital pseudarthrosis of the fibula are reported, all with prepseudarthrotic involvement of the omolateral tibia. In patients with this condition, correction of valgus deformity should be deferred until puberty, and the occurrence of tibial fractures should be prevented by means of leg splints.

Relationship between the efficiency of muscular work during jumping and the energetics of running.

The running economy of seventeen athletes was studied during running at a low speed (3.3 m X s-1) on a motor-driven treadmill. The net energetic cost during running expressed in kJ X kg-1 X km-1 was on average 4.06. As expected, a positive relationship was found between the energetic cost and the percentage of fast twitch fibres (r = 0.60, n = 17, p less than 0.01). In addition, the mechanical efficiency during two different series of jumps performed with and without prestretch was measured in thirteen subjects. The effect of prestretch on muscle economy was represented by the ratio between the efficiency of muscular work performed during prestretch jumps and the corresponding value calculated in no prestretch conditions. This ratio demonstrated a statistically significant relationship with energy expenditure during running (r = -0.66, n = 13, P less than 0.01), suggesting that the elastic behaviour of leg extensor muscles is similar in running and jumping if the speeds of muscular contraction during eccentric and concentric work are of similar magnitudes.