Estimation of body composition in competitive swimmers by means of three different techniques.

Up to now controversial reports have been published in regard to the beneficial effects of swimming, a non-weight-bearing activity, on bone mass (BM). Therefore, the aim of this study was to investigate the effects of competitive swimming practice on the bone mineral density (BMD) and bone mineral content (BMC) as well as on the different factors of body composition. For this purpose, competitive swimmers (16 males and 16 females) were selected as subjects in order to investigate the influence of swimming on the three main factors of body composition (BMC, lean body mass [LBM] and body fat [BF]) of the human body. The latter were estimated using three different approaches: the skinfold, the dual energy x-ray absorptiometry (DEXA) and the whole body potassium (K-40) methods. Since BM and LBM are also related, the possible correlations between shoulder strength (extensions and flexion movements) and performance with BMD, BMC, LBM and BF were also investigated. Our results showed that BMD was not affected by swimming exercise since z (%) values were similar between swimmers and their respective age-matched controls. Swimmers also showed lower BF and increased LBM in the region of upper extremities (arms and trunk) as compared to their lower extremities (legs), a finding which is typical for the sport they are trained for. Also, comparison between sexes showed that males had a more central distribution of fat when compared to females, in which BF was built up in the region of legs. Furthermore, shoulder strength and performance were significantly related (p < 0.05) to age, BMC, and LBM while performance was also significantly related (p < 0.05) to all the other BM indices. So, mineralization of the bone is important for shoulder muscular strength which is subsequently related to performance. We used the DEXA because it enabled the direct estimation of the three factors of body composition (BM, BF and LBM).

Maximal lactate values following competitive performance varying according to age, sex and swimming style.

Peak blood lactate concentration for a given individual in a given event could be considered as indicator of exercise effort, especially if the race is fast as it occurs following competitive swimming events. The present study attempts to describe the postcompetition lactate profile across all the swimming distances and strokes according to the age and sex of the swimmer. Blood samples (100 micro lambda) were taken from an arterialized fingertip of a total of 337 swimmers (171 males and 166 females) at the end of 3rd and 6th minutes of competition over 50 to 1500 meter distances and for the following 3 age group divisions: AGE1 = > 18 years of age, AGE2 = 16-17 years of age and AGE3 = 14-15 years of age. For AGE1 group the subjects who were picked up for testing were all the first three who met the criteria for this age category in the OPEN winter and summer National and Provincial Championships. For AGE2 and AGE3 groups the subjects who were picked up for testing were ranked among the first three in their age group winter and summer National and Provincial Championships. Results showed that the highest mean peak lactate values for groups AGE2 and AGE3 were recorded in 200 medley event for both sexes while for group AGE1 the highest mean peak lactate value was recorded in 200 and 400 meter medley events for males and females respectively. On the other hand, the lowest mean lactate value was recorded in long distance events of 1500 and 800 meters for males and females respectively and for all the age group divisions. Furthermore, swimming performance was related to peak lactate values which subsequently was independent of sex but dependent on age with higher lactate values and older age documented by the subjects with faster times.

Somatometric variables for preadolescent swimmers.

The present study comprises one facet of a research program focused on describing and seeking implications of different physiques among preadolescent swimmers specialized in different swimming events. The subjects were 231 swimmers of both sexes aged 12 and 13 years. On each subject data were collected for 13 measures of body size, 4 indices of body form and measures of body composition. It was found: (1) The sprint group was the tallest and heaviest, compared to the others, for both sexes. This group also had the highest values for upper and lower limbs, hand and foot lengths. (2) The back group had values quite close to the ones of sprint group. (3) The long distance group was the shortest and lightest group for males and the lightest group for females. (4) The female fly group had a distinct physical structure with lowest values for height, upper and lower limb lengths as well as hip width. (5) Significant but low correlations were obtained between performance and somatometric variables such as height, leg, arm, and hand lengths. The results of this study support the conclusion that for swimmers, participating in different events, variation in body size and form is already present at an early age. As more data will be collected overtime the profile of the age-group swimmer will be more distinct making easier the selection of a particular swimming event.

Effects of atropine and pyridostigmine in heat-stressed patas monkeys.

The effects of a single intramuscular atropine injection (0.03 mg.kg-1) and a chronic oral pyridostigmine treatment (0.4 mg.kg-1, 3 times/day over a period of 7 d) on the thermoregulatory effector responses of unanesthetized patas monkeys were investigated using indirect calorimetry. The effects of atropine treatment on the thermoregulatory effector responses of patas monkeys exposed to 25 degrees and 35 degrees C were qualitatively similar but quantitatively greater at 35 degrees C. At 35 degrees C atropine decreased sweating (Esw) 52%, increased rectal temperature (Tre), mean skin temperature (Tsk), metabolic rate (MR), and whole body conductance (K), and elicited a consistent 11% increase in heart rate (HR). Daily oral pyridostigmine treatment to patas monkeys produced a significant 25-30% drop in serum cholinesterase activity with no chronic effects on thermoregulatory or cardiovascular functions. The acute effects of oral pyridostigmine treatment in this species included transient 12% and 15% decreases in MR and HR, respectively, and a transient 25% increase in Esw. The latter was associated with significant acute reductions in Tre and Tsk which lasted at least 120 min following pyridostigmine administration. It is concluded that the patas monkey is an excellent animal model for studies to evaluate the effects of neuroactive agents on thermoregulatory and other physiological functions which are difficult, if not impossible, to perform on humans.