A new equation to estimate temperature-corrected PaCO2 from PET CO2 during exercise in normoxia and hypoxia.

End-tidal PCO2 (PET CO2 ) has been used to estimate arterial pressure CO2 (Pa CO2 ). However, the influence of blood temperature on the Pa CO2 has not been taken into account. Moreover, there is no equation validated to predict Pa CO2 during exercise in severe acute hypoxia. To develop a new equation to predict temperature-corrected Pa CO2 values during exercise in normoxia and severe acute hypoxia, 11 volunteers (21.2 ± 2.1 years) performed incremental exercise to exhaustion in normoxia (Nox, PI O2 : 143 mmHg) and hypoxia (Hyp, PI O2 : 73 mmHg), while arterial blood gases and temperature (ABT) were simultaneously measured together with end-tidal PCO2 (PET CO2 ). The Jones et al. equation tended to underestimate the temperature corrected (tc) Pa CO2 during exercise in hypoxia, with greater deviation the lower the Pa CO2 tc (r = 0.39, P < 0.05). The new equation has been developed using a random-effects regression analysis model, which allows predicting Pa CO2 tc both in normoxia and hypoxia: Pa CO2 tc = 8.607 + 0.716 × PET CO2 [R(2) = 0.91; intercept SE = 1.022 (P < 0.001) and slope SE = 0.027 (P < 0.001)]. This equation may prove useful in noninvasive studies of brain hemodynamics, where an accurate estimation of Pa CO2 is needed to calculate the end-tidal-to-arterial PCO2 difference, which can be used as an index of pulmonary gas exchange efficiency.

A reliable unipedal stance test for the assessment of balance using a force platform.

BACKGROUND: The aim was to develop a unipedal stance test for the assessment of balance using a force platform. METHODS: A single-leg balance test was conducted in 23 students (mean ± SD) age: 23 ± 3 years) in a standard position limiting the movement of the arms and non-supporting leg. Six attempts, with both the jumping (JL) and the contralateral leg (CL), were performed under 3 conditions: 1) eyes opened; 2) eyes closed; 3) eyes opened and executing a precision task. The same protocol was repeated two-week apart. RESULTS: The mean and the best result of the six attempts performed each day were taken as representative of balance. The speed of the centre of pressure (CP-Speed) showed excellent reliability for the "best result" analysis in all tests (ICCs 0.87-0.97), except in the test with the eyes closed performed on the CL (ICC<0.4). The CP-Speed had better reliability with the "best result" than with the "mean result" analysis (P<0.05), whilst no significant differences were observed between the JL and the CL (P=0.71 and P=0.96 for mean and best results analysis, respectively). A lower dispersion in the Bland and Altman graph was observed with the eyes opened than closed, and the dynamic test. CONCLUSION: The single-leg stance balance test proposed is a reliable method to assess balance, especially when performed in a static position, with the eyes opened and using the best result of six attempts as reference, independently of the stance leg.

Enhanced bone mass and physical fitness in young female handball players.

This study evaluates the effect of physical activity on the bone content (BMC) and density (BMD) in 51 girls (14.2+/-0.4 yr). Twenty-four were placed in the handball group as they have been playing handball for at least 1 year (3.9+/-0.4). The other 27 who did not perform in any kind of regular physical activity other than that programmed during the compulsory physical education courses comprised the control group. Bone mass and areal density were measured by dual-energy X-ray absorptiometry (DXA). The maximal leg extension isometric force in the squat position with knees bent at 90 degrees and the peak force, mean power, and height jumped during vertical squat jump were assessed with a force plate. Additionally, 30-m run (running speed) and 300-m run (as an estimate of anaerobic capacity) tests were also performed. Maximal aerobic capacity was estimated using the 20-m shuttle-run tests. Compared to the controls, handballers attained better results in the physical fitness tests and had a 6% and 11% higher total body and right upper extremity lean mass (all P<0.05). The handballers showed enhanced BMC and BMD in the lumbar spine, pelvic region, and lower extremity (all P<0.05). They also showed greater BMC in the whole body and enhanced BMD in the right upper extremity and femoral neck than the control subjects (all P<0.05). As expected, total lean mass strongly correlated with total and regional BMC and BMD (r=0.79-0.91 P<0.001). Interestingly, 300-m running speed correlated with BMC and BMD variables (r=0.59-0.67 and r=0.60-0.70, respectively; all P<0.001). Multiple regression analysis showed that the 30-m running speed test, combined with the height and body mass, has also predictive value for whole-body BMC and BMD (R=0.93 and R=0.90, P<0.001). In conclusion, handball participation is associated with improved physical fitness, increased lean and bone masses, and enhanced axial and appendicular BMD in young girls. The combination of anthropometric and fitness-related variables may be used to detect girls with potentially reduced bone mass.