The Z-disk protein α-actinin-3 is only expressed in type II muscle fibres, which are responsible for generating forceful contractions at high velocity. Despite the evolutionary conservation of α-actinin-3, approximately one in every five Caucasians of European ancestry is totally deficient in this protein, due to homozygosity for a R577X polymorphism in the ACTN3 gene. This, together with the results of recent research on elite athletes, suggests that the “null” XX polymorphism might confer some advantage to endurance performance events. To test this hypothesis, we studied the frequency distribution of R577X genotypes in a group of 50 top-level male professional cyclists (26.9 ± 0.4 yrs [mean ± SEM]; V·O_2max: 73.5 ± 0.8 ml · kg^-1 · min^-1). Their results were compared with those of a group of 52 Olympic-class male endurance runners (26.8 ± 0.6 yrs; V·O_2max: 73.3 ± 0.8 ml · kg^-1 · min^-1) and 123 healthy, sedentary male controls. All subjects were Caucasian, and of European ancestry. No significant differences (p > 0.05) were found between groups: RR: 28.5 %; RX: 53.6 % and XX: 17.9 % in controls; RR: 28.0 %; RX: 46.0 % and XX: 26.0 % in cyclists; and RR: 25.0 %; RX: 57.7 %; XX: 17.3 % in runners). No differences were found in indices of endurance performance (VO_2peak or ventilatory thresholds) between athlete carriers of each R577X genotype. In summary, although the α-actinin-3 deficient XX genotype may be detrimental for sprint performance in humans, the R577X polymorphism of the ACTN3 gene does not appear to confer an advantage on the ability of male athletes to sustain extreme endurance performance.

The aims of this study were to measure the aerodynamic drag in professional cyclists, to obtain aerodynamic drag reference values in static and effort positions, to improve the cyclists' aerodynamic drag by modifying their position and cycle equipment, and to evaluate the advantages and disadvantages of these modifications. The study was performed in a wind tunnel with five professional cyclists. Four positions were assessed with a time-trial bike and one position with a standard racing bike. In all positions, aerodynamic drag and kinematic variables were recorded. The drag area for the time-trial bike was 31% higher in the effort than static position, and lower than for the standard racing bike. Changes in the cyclists' position decreased the aerodynamic drag by 14%. The aero-helmet was not favourable for all cyclists. The reliability of aerodynamic drag measures in the wind tunnel was high (r > 0.96, coefficient of variation < 2%). In conclusion, we measured and improved the aerodynamic drag in professional cyclists. Our results were better than those of other researchers who did not assess aerodynamic drag during effort at race pace and who employed different wheels. The efficiency of the aero-helmet, and the validity, reliability, and sensitivity of the wind tunnel and aerodynamic field testing were addressed.

The aim of this study was to design and validate a vertical jump assessing system based on flight time measurements. Hence, the first phase of this study consisted of programming the software SportJumpv-1.0 and adapting a contact mat and a computer mouse in order to record the flight and contact times of a jump test. In the second phase, 9 subjects made 12 maximal and submaximal vertical single and rebound jumps. Thus 108 flight times and 36 contact times were simultaneously obtained with five different systems: ErgoJump Bosco System (PS), SportJump-v1.0 (SJ), Force Plate (FP), High-speed camera (HSC), and a Led (LED) filmed with a high-speed camera; FP was considered as the reference system. No significant differences were found either between SJ and LED, or between FP and HSC systems. SJ and LED overestimate flight time (9 ms and p < 0.001) and underestimate contact time in respect to FP values. PS underestimates flight time regarding FP values (4 ms and p < 0.01). In spite of the differences obtained between the systems, the errors found are constant. Those slightly depend on the subject's body mass for the systems that are connected to a contact mat. A high correlation between all of them was obtained (r ∼ 1 and p < 0.001). The SJ system was validated for an accuracy of 500 Hz, and it was shown to be a useful tool in measuring flight and contact times during jumping. The differences and correlations found between the five systems show that it is necessary to take into account which system is being used when analyzing vertical jump performance.

To evaluate the associations between physical fitness levels, health related quality of life (HRQoL) and sarcopenic obesity (SO) and to analyze the usefulness of several physical fitness tests as a screening tool for detecting elderly people with an increased risk of suffering SO. Cross-sectional analysis of a population-based sample. Non-institutionalized Spanish elderly participating in the EXERNET multi-centre study. 2747 elderly subjects aged 65 and older. Body weight, height and body mass index were evaluated in each subject. Body composition was measured by bioelectrical impedance. Four SO groups were created based on percentage of body fat and relative muscle mass; 1) normal group, 2) sarcopenic group, 3) obesity group and 4) SO group. Physical fitness was evaluated using 8 tests (balance, lower and upper body strength, lower and upper body flexibility, agility, walking speed and aerobic capacity). Three tertiles were created for each test based on the calculated scores. HRQoL was assessed using the EuroQol visual analogue scale. Participants with SO showed lower physical fitness levels compared with normal subjects. Better balance, agility, and aerobic capacity were associated to a lower risk of suffering SO in the fittest men (odds ratio < 0.30). In women, better balance, walking speed, and aerobic capacity were associated to a lower risk of suffering SO in the fittest women (odds ratio < 0.21) Superior perceived health was associated with better physical fitness performance. Higher levels of physical fitness were associated with a reduced risk of suffering SO and better perceived health among elderly. SO elderly people have lower physical functional levels than healthy counterparts.