The end points will be i. muscle protein synthesis, ii. muscle protein breakdown, iii. bulk femoral blood flow and iv. nutritive femoral blood flow in subjects of different ages or following different exercise or nutraceutical intervention. A power calculation suggests that this study will need 10 subjects per group to detect (with α of 0.05 and β of 0.85) a 25 % difference between groups in biological variables, results the investigators have been able to achieve for similar work in the past.