Vigor Now Male : A study in the Journal of Clinical Endocrinology and Metabolism also linked low testosterone to an increased mortality rate. Half the group exercised as normal while the other half were given the testosterone boosting drug Tribulus Terrestris . If you think that sounds like hyperbole then take a look at this study published in the Journal of Sport and Health Science, which demonstrated just how important testosterone is for maintaining muscle. https://www.nutriminimart.com/vigornow-male/