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Aim: Exercise training is a strong stimulus for vascular remodelling and could restore age-induced vascular alterations. The purpose of the study was to test the hypothesis that an increase in vascular bed filtration capacity would corroborate microvascular adaptation with training. Methods: We quantified (1) microvascularization from vastus lateralis muscle biopsy to measure the capillary to fibre interface (LC/PF) and (2) the microvascular filtration capacity ( Kf) in lower limbs through a venous congestion plethysmography procedure. Twelve healthy older subjects (74 ± 4 years) were submitted to a 14-week training programme during which lower-limbs were trained for endurance exercise. Results: The training programme induced a significant increase in the aerobic exercise capacity of lower limbs (+11% Vo2peak; P < 0.05; +28% Citrate Synthase Activity; P < 0.01). Kf was largely increased (4.3 ± 0.9 10−3 mL min−1 mmHg−1 100 mL−1 post-training vs. 2.4 ± 0.8 pre-training, mean ± SD; P < 0.05) and microvascularization developed as shown by the rise in LC/PF (0.29 ± 0.06 post- vs. 0.23 ± 0.06 pre-training; P < 0.05). Furthermore, Kf and LC/PF were correlated ( r = 0.65, P < 0.05). Conclusion: These results demonstrated the microvascular adaptation to endurance training in the elderly. The increase in Kf with endurance training was probably related to a greater surface of exchange with an increased microvessel/fibre interface area. We conclude that measurement of the microvascular filtration rate reflects the change in the muscle exchange area and is influenced by exercise training. [ABSTRACT FROM AUTHOR]

Muscle microvascularization is usually quantified in transverse sections, in absolute terms (capillaries around fibres, CAF, or capillary-to-fibre ratio, C/F) or as CAF related to fibre area (CAF/area, CAFA). The capillary-to-fibre perimeter exchange ratio (CFPE) has been introduced in order to assess the role of the capillary-to-fibre interface in resistance to O2 diffusion. The ratio between the length of capillaries in contact with fibres and fibre perimeter (LC/PF) has also been used as an index for capillary tortuosity. The possibility of change in capillary tortuosity with endurance training was not considered in previous studies. Consequently, this study investigated the effect of 14 weeks of endurance training on muscle microvascularization, including microvessel tortuosity, in 11 elderly men (8th decade). Microvessels were analysed using the CD31 antibody. Together with the significant increase in peak oxygen exchange and citrate synthase activity, there was a significant increase in C/E While CFPE and CAFA remained unchanged, an important finding was the dear increase in LC/PF (56%; P < 0.001) for a same sarcomere length. We also found a strong correlation between oxidative enzyme activity and LC/PF both before and after training. These results indicate that endurance training induces significant remodelling in the microvessel network in elderly men and that an increase in the degree of microvessel tortuosity would be an important mechanism of adaptation to endurance training. [ABSTRACT FROM AUTHOR]

Mathematical methods to statistically compare the relative accuracy of physiological monitoring devices to reference measurements are scarce. We developed such a method to compare any number of devices to each other as well as to reference values. This new statistical comparative procedure uses a combination of different known mathematical processes. The method allows the separation of the error of the devices into two components, the first, being systematic, can be easily amended, while the second, inherent to the technical limitations of the measuring device as well as to the physical properties of the explored phenomenon, cannot be corrected and will thus be used as the comparative criterion for statistics. That method, which is easy to implement should ease comparisons of the accuracy of any number of devices as well as comparison of other sets of physiological values, by giving an easy access to statistical results. [ABSTRACT FROM AUTHOR]