For some reason during the last six weeks, I'm always yawning in the middle of my weight workouts at least 3 or 4 times an hour. It happens whether I do my workout in the morning, during my lunch break, or in the evening. In the morning, I always have some men's vitamins and a protein smoothie an hour before my workout for energy, but it's still a problem. Later in the day, I always try to have a protein smoothie an hour before I get to the gym. I'm getting more rest as I've changed my sleep patterns and I've never had this problem before. Do I need something for an extra boost because I'm (gasp!) getting older? Do I need something to recharge my system? I don't seem to have this problem on my cardio days.  —Rod, Las Vegas, NV

You actually answered your own question, in the last

sentence of your e-mail.  Resistance training is largely anaerobic (lacking oxygen) while cardiovascular training is aerobic (in the presence of oxygen).  There are many theories out there about why people yawn during a weight workout.  One of these theories is that your body needs more oxygen due to the nature of the anaerobic weight exercise.  Yawning is your body's very effective way of getting oxygen back into your system.

The other theory about yawning during workouts comes down to air circulation in gyms, but based upon your question, I doubt that this is the issue behind your yawning.  Since it happens morning, noon or night, (but not during your cardio sessions) my guess is that you are probably working out harder than normal during your weight training time and your body is responding in kind by wanting more oxygen intake.

In terms of supplementation, there are many energy supplements out there, but many of these work by jolting your system with large doses of caffeine which will leave you even more burned out and dependent later on.  Remember the physics rule: every action has an equal and opposite reaction.  If you want a natural energy boost, try drinking green tea in advance of your time in the gym.  Green tea contains L-theanine, an amino acid that not only gives the tea its unique flavor, but also promotes relaxation and modifies the stimulating effects of the caffeine in green tea.  If you're looking for this same effect in pill form, you might want to try Going, Going, Gone. I like it because it's 100 percent natural & organic, contains green tea extract, chromium, and other antioxidants with no harmful chemicals (or ephedrine-based plant sterols).