Reversing Muscle Loss With Exercise Training and Daily Consumption of Pomegranate Juice

The investigators have shown that chronic pomegranate juice consumption in both young untrained and weight-trained men partially protects muscles against the damage done from performing high intensity eccentric contractions and that it accelerates recovery of function. Clearly, skeletal muscle is a target for some of the healthful molecules in pomegranate juice. However, the most widespread and serious ailment to strike skeletal muscle is sarcopenia (e.g.; loss of muscle mass and becoming 'frail') with age due predominantly to a loss of 'fast-twitch' muscle fibers. Since adults rarely sprint or exert maximal force or power, they rarely use their fast-twitch muscle fibers, which thus degenerate greatly with age. Usually, about one-half of a person's muscle fibers are fast-twitch. It is the investigators' hypothesis that the combination of power exercise training and pomegranate juice supplementation (POM) over 10 weeks, will elicit greater improvements in maximal muscular power and functional physical abilities compared to power training with a placebo. The investigators also will identify changes in size and composition of leg muscles (MRI) and of the whole body (DEXA). The investigators simple logic is that muscles deteriorate with age because they are 'turned-off' and that exercise training can turn them 'back-on', but in order for the muscle fibers to fully repair when turned 'back-on' with exercise, they might benefit from agents known to foster repair, such as the natural polyphenols in pomegranate juice. It has recently been found that polyphenols are metabolized into urolithins which improve muscle cell function due to increased mitophagy. The investigators aim to determine if power training and pomegranate juice have additive effects in promoting improvements of muscle function and mass in men and women age 50-70 y.

A second purpose is to include a cardio-metabolic exercise training stimulus into the workout without compromising the efficacy of the power training. One feature of cardio-metabolic training is an increase in muscle mitochondria and oxygen utilization which might improve muscle fiber repair. The 'power training' will consist of maximal effort 4 sec sprints on a cycle ergometer with no added resistance with the only load being that of the inertia of the flywheel as the subject accelerates from 0 to their maximal RPM's while cycling (100-150 RPM)('inertial load ergometer'; ILE). The power training will be accomplished by having the subject complete 15-30 sprints in a 15 min period. During the training bouts, initially the subjects will rest 56 s between sprints (week 1- complete 15 sprints in each15 min bout), and then 41 s between sprints (weeks 2-5 and complete 20 sprints) and finally 26 s between sprints (weeks 6-10 and complete 30 sprints). The shorter rest periods (41 s and 26 s) will result in incomplete recovery of the cardio-respiratory system and thus the oxygen consumption and heart rate will average 50-70% of maximal values, which is a similar intensity as jogging, but without the jarring of foot strike.