I am wondering if there have been any studies done on wether the use of thermogenics aid in increases in strength due to getting more reps than one normally would due to increased energy or a motivational factor? If so, what was said exactly?
Thermogenics are certainly popular fitness supplements. One could say that a large portion of the fitness industry is fuelled by ephedrine (also called Ma-Huang) and caffeine mixtures. Absolute strength is an aspect that is not often investigated with these compounds, but the smattering of available data shows this aspect to not be affected by caffeine or ephedrine. Anaerobically speaking though, caffeine and ephedrine combinations have been shown to increase power output in the early phase of the 30 second Wingate test (used to measure peak power output, mean power for 30 seconds and fatigue rate), increase time to exhaustion in high and very high intensity exercise, and lower perceived exertion. From a psychological standpoint, I am sure there are those that would swear that their pre-workout "Thermo Shredded Turbo Tea" provides them with greater intensity, allowing them to move more weight and power through their workout with vigor. If that is the case, then sure, it may affect strength.
Where thermogenic supplements such as caffeine or caffeine and ephedrine combinations typically shine is in aerobic endurance, delaying the onset of fatigue, lowering perceived exertion and increasing power output during timed or distance events. As stimulants, these compounds act upon the CNS and it has historically been proposed that the ergogenic benefits are due to an increase in free fatty acid availability, sparing glucose. Additionally, caffeine improves alertness and may help the athlete focus on the task at hand. However, newer information on the ergogenic contribution of caffeine suggests that the previous model provides only a portion of the benefits. It appears that caffeine may also exert it's influence neurally by altering muscle force sensations, allowing for greater motor unit force production and delaying the onset of fatigue. It is the ionic environment intracellularly that may facilitate this increased firing.
It is interesting to note that coffee and other caffeinated beverages do not exert the ergogenic benefits seen with supplemental caffeine.