Effects of Nitrate supplementation during cycling and walking in old and young healthy men

The general objective of the thesis is to investigate the effects induced by nitrates (NO3-) supplementation during muscular exercise at moderate and severe intensity, in elderly (60-75 years) and young (20-35 years) people. The NO3- contribution, equal to 8.0 mM dissolved in 0.25 L of solution, was provided by means of beetroot juice and continued for a period of 8 days. We evaluated the responses of oxidative metabolism, taking into consideration both central factors as well as peripheral factors. The peculiar and most original aspect of the study is aimed at understanding the effects of NO3- supplementation in the elderly. The interest was also that of understanding the mechanisms involved in oxidative metabolic regulation NO3-mediated, in the elderly. The aging process is associated with functional and structural changes, especially in the cardiovascular and muscular systems, leading to alterations in oxidative metab- olism. The marked impairment of the transport of O2 and its peripheral use, together with the progressive loss of strength and muscle mass, are responsible for the signifi- cant and progressive worsening of V ̇ O2 kinetics that characterizes the elderly. Also, cardiovascular responses following a nitrate supplementation have been in- vestigated. Indeed, literature remarks that, nitrates are involved both in the circulatory (endothelial) and metabolic (mitochondrial) levels. The interest also was to analyze whether nitrates in the two populations (old and young) have a significant effect on the main hemodynamic components. We intent also to investigate the effects at met- abolic level induced by nitrate supplementation during exercise. Moreover, the metabolic cost of walking per unit of distance travelled is greater in older people than in young adults even when they are healthy and free from gait impairment. Other data indicate that the increase in the cost of the metabolic cost of the walk occurs around the 7th decade of life that coincides approximately with the time in which the changes occur in different biomechanical and bioenergetical factors of walking. 11 The study was developed in order to describe the trend of energy cost of locomo- tion on a treadmill at different intensities administered by varying the speed and slope of the instrument. The main end point is the verification of the efficacy of BR supplementation in improving muscle efficiency in various type of locomotion. In particular, we intend to check if NO3-: i) areabletoreducetheenergycostofexerciseinelderlysubjectsinthemoderate and severe intensity domain; ii) are able to improve muscle efficiency in relation to a greater availability of ox- ygen and its use at the peripheral level. In short, the aim of the studies was to evaluate, through an integrative approach, the effects of nitrate supplementation on skeletal muscle oxidative metabolism during ex- ercise. Conclusions: Main results of these studies suggest that supplementation on nitrate leads to an im- provement in the efficiency in the elderly during low-intensity exercise and confirms the improvement in the young during high-intensity exercise. However, these improvements are probably not due to peripheral improvements in oxygen transport and extraction, so they must be sought elsewhere, for example at the cellular level.