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There is a disparity in the information about the heritability of the response of muscle anaerobic metabolism to exercise and the use of explosive power, as well as a lack of information concerning the genetic determinants of this form of work, as measured using different specific physical tests. We applied a battery of some of the commonly employed procedures (Ergojump, Wingate, maximal accumulated oxygen deficit, excess post-exercise oxygen consumption, and delta lactate concentration) to a group of 32 Caucasian male twins, 8 monozygotic and 8 dizygotic pairs, who had similar environmental backgrounds. Results were studied using a heritability index (HI). Zygosity was determined using the identity of erythrocyte antigens, protein and enzyme polymorphism and human leucocyte antigen serologic types between co-twins. Significant HI values (P< 0.05) were found in the following tests: maximal 5 s power (HI = 0.74) and total power in a 30 s interval (HI = 0.84) in the Wingate test, maximal lactate concentration (HI = 0.82) and delta lactate concentration (HI = 0.84) in the maximal progressive test, as well as in the 2nd (HI = 0.93) and in the 3rd min (HI = 0.92) of recovery after the deficit test. In this study, the most relevant findings were: firstly, significant HI values for many of the variables studied; secondly, the HI values of the parameters used to evaluate explosive power were higher than those of lactic acid capacity and thirdly, the HI of certain variables from different tests measuring, in theory, similar qualities, were different.

The differences in ventilatory response to exercise of some highland ethnic communities is a controversial issue. We have evaluated the differences in ventilatory response to exercise at sea level between two groups of elite climbers, four Himalayan Sherpas (S) and four Caucasian lowlanders (C), after descent from extreme altitude. All of them performed a progressive-intensity exercise test on a treadmill under normoxic conditions. Pulmonary gas exchange was obtained until exhaustion by means of an automatic gas-analyzer system. Significant differences in expired ventilation and carbon dioxide production were found between the two groups, the VE x VO2(-1) being lower in the S at rest (41.9 +/- 5) in comparison with C (48.7 +/- 9) (P < 0.05), higher at medium loads of the test (S = 28.2 +/- 4 vs. C = 25.7 +/- 2; P < 0.05) and reaching similar values at higher loads (S = 34.5 + 2 vs. C = 35.6 +/- 4; NS). We conclude that the special ventilatory response observed in these highlanders could explain their adaptation to altitude, allowing higher oxygen blood saturation at medium working loads and reducing the risk of neurological injury caused by a high ventilatory response when exercising at high intensity effort under extreme altitude environment.

Creatine supplementation has been shown by several authors to improve physical performance in very high intensity, intermittent, exercises. The effect on performance, as well as in plasma creatine and lactate concentrations has been studied in a group of twelve sprinters of national class when running a distance of 150 m on two occasions, before and after creatine (or placebo) supplementation for the previous three days. The most important differences in the biochemical parameters analyzed have been in plasma creatinine concentration, which increased substantially both before and after the race in the group that had received a daily supplement of 25 grams of creatine monohydrate for the previous three days. Creatine supplementation, therefore, did not improve physical performance, in the conditions, when running a 150 m distance.

Himalayan Sherpas are well known for their extraordinary adaptation to high altitude and some of them for their outstanding physical performance during ascents to the highest summits. To cast light on this subject, we evaluated the cardiorespiratory response during exercise at sea level of six of the most acknowledged Sherpa climbers, mean age (+/- SD) 37 (+/- 7) yr old. Continuous electrocardiogram and breath-by-breath pulmonary gas exchange until exhaustion were obtained by following the Bruce protocol. We detected a maximal oxygen uptake (VO2max) of 66.7 (+/- 3.7) mL-min-1.kg-1, maximal cardiac frequency of 199 (+/- 7) beats.min-1, and ventilatory anaerobic threshold at 62 (+/- 4) % of VO2max. These factors could help to explain the greater performance level shown by several elite climbers of this ethnic group. The high functional reserve demonstrated by this very select group of highlanders could be associated with natural selection and with special physiological adaptations probably induced by long-training in a hostile environment.

Whether changes in the training schedule are capable of modifying the daily pattern of performance has been studies. Twelve swimmers were selected to determine their performance in 25 meter crawl races. Their body temperature was also measured. This group was subsequently divided into 3 subgroups: Sub-group 1, made up of 2 subjects who acted as the control subgroup, trained only in the afternoon; Sub-group 2, composed of 5 subjects, trained only in the morning; and Subgroup 3, also made up of 5 subjects, trained in the afternoon but with an additional session of 10 min of swimming in the morning. All subjects followed their corresponding training pattern for three weeks after which they were subjected to a second study or testing day. Thereafter, they all trained one more week according to the same habitual schedule in the evening; after that, they were tested again. A significant variance in the performance time was observed throughout the day (a maximum performance being observed at around 20:30 h), although the changes introduced in the training schedule did not modify the curve of performance.

1. The power of the aerobic metabolic pathway correlates well with successful physical performance in endurance sports events. The ability to alter the pathway through training presents well-known limitations, and consequently a good genetic endowment is essential to participate in elite sporting activities. 2. In 32 subjects (16 healthy pairs of male twin sportsmen, 8 monozygotic and 8 dizygotic) zygosity was determined by means of the genetic analysis of human leucocyte antigen (HLA) system specificities at class I and II loci and other genetic variants. The subjects performed a progressive exercise test on a treadmill to ascertain the maximal oxygen uptake (VO2max), measured by an automatic breath-by-breath analyser. We have considered the relationship between the A, B and C loci of the HLA system and VO2max. 3. We found a high correlation between the presence of both HLA A2 and A11 and VO2max. In the A2A11 group (n = 6) we found a VO2max (mean +/- SD) equal to 71 +/- 4 ml min-1 kg-1. The group without this pair of alleles (n = 26) showed a much lower aerobic power (58 +/- 5 ml min-1 kg-1). Differences between the two groups were found to be largely significant (P < 0.001). It is noteworthy that in two pairs of dizygotic twins, the higher VO2max value corresponded to the twin with the A2A11 allele. 4. The very marked concordance between the presence of the A2A11 locus of the HLA system and the VO2max could be of great interest for the identification of outstanding performers.

To detect whether the drop in performance around lunch has any direct association with the time of food ingestion, a group of 8 sprinters were studied for 5 consecutive Saturdays. On each testing day, the times achieved during 80 meter sprints performed at eight different times of the day separated by 2 hour intervals were recorded. The 1st and 4th testing days, had identical sleep and mealtime schedules, and were therefore considered "control days", while on the 2nd and 3rd testing days the schedule was brought forward ("advanced") or backward ("delayed") by 2 hours respectively. On the 5th testing day the sleep-wake cycle was brought forward 2 hours without changing the mealtime schedule. A post-lunch dip (PLD) was detected on all testing days although at different times. No significant differences in performance were observed between days 1 and 4 while there were differences in performance during the other testing days. It is worth pointing out that PLD occurred at about 15:00 h on the control days, with significant differences between the 2nd (p < 0.05) and 3rd days (p < 0.05), and with the deterioration in performance starting at 15:00 h on the 3rd day despite the fact that lunch had been served at 16:00 h. In conclusion, PLD does not appear to be directly linked to the time of lunch, although lunch itself could potentiate its effects. It is also worth mentioning the fact that this deteriorating effect does not occur after any other meals of the day.

Objective: To test the hypothesis that saliva lactate concentrations may reflect those present in blood and that saliva lactate can be used as a very convenient and useful variable in the study of anaerobic metabolism., Methods: Parallel determinations were made of lactate in saliva and in capillary blood samples, obtained at 3 min intervals from nine individuals during the performance of a maximum graded exercise test on a cycle ergometer against increasing workloads (from 25 up to a maximum of 300 W). Lactate determinations were done by means of an electroenzymatic method using 25 microliters samples in both types of fluids., Results: For each situation, the concentration of lactate in saliva was shown to be about 15% of that in plasma but it followed the same pattern of evolution during the exercise test. A good correlation (r = 0.81) between blood and saliva lactate concentrations was found. The precision of the method was very good, with a coefficient of variation ranging (n = 10) between 2.2% for samples with very low lactate concentrations and 0.7% for sample with moderate lactate concentrations. Lactate appeared to be very stable in saliva over a period of 40 days after collection, when kept at 4 degrees C. The values obtained after this period were virtually identical to those shown in fresh samples., Conclusions: Determination of lactate in saliva can be used as an alternative to determination in blood, overcoming most of the drawbacks of the procedures being used at present, since the collection of the samples required no special expertise.

1. The potential risk of brain damage when low-landers attempt to climb the highest summits is a well-known fact. However, very little is known about what occurs to Himalayan natives, perfectly adapted to high altitude, when performing the same type of activity. 2. Taking into account their long-life climbing experience at extreme altitudes, we examined seven of the most recognized Sherpas with the aim of performing a comprehensive neurological evaluation based on medical history, physical examination and magnetic resonance brain imaging. We compared them with one group of 21 lowland elite climbers who had ascended to altitudes of over 8000 m, and another control group of 21 healthy individuals who had never been exposed to high altitude. 3. While all of the lowland climbers presented psychoneurological symptoms during or after the expeditions, and 13 of them (61%) showed magnetic resonance abnormalities (signs of mild cortical atrophy and/or periventricular high-intensity signal areas in the white matter), only one Sherpa (14%) showed similar changes in the scans, presenting neurological symptoms at extreme altitude. The neurological examination was normal in all three groups, and no neuroimaging abnormalities were detected in the control group. 4. The significant differences, in both clinical and neuroimaging terms, suggest that Sherpa highlanders have better brain protection when exposed to extreme altitude. Although the key to protection against cerebral hypoxia cannot be established, it is possible that an increase in the usually short period of acclimatization could minimize brain damage in those low-landers who attempt the highest summits without supplementary oxygen.