I will be having dinner with my good friend "The Movement Doctor" tonight, so I am super excited to learn lots of new stuff. Check out her website b
elowESSENTIAL STRENGTH
on to the study
EFFECT OF PHYSIOLOGICAL LEVELS OF CAFFEINE ON Ca2+ HANDLING AND FATIGUE DEVELOPMENT IN XENOPUS ISOLATED SINGLE MYOFIBERS.
Rosser JI, Walsh B, Hogan MC. University of California - San Diego.
The purpose of the present study was to determine whether exposure to exogenous physiological concentrations of caffeine influence contractility, Ca(2+) handling, and fatigue development in isolated single Xenopus laevis skeletal muscle fibers. After isolation, two identical contractile periods (separated by 60 min rest) were conducted in each single myofiber (n=8) at 20 degrees C. During the first contractile period, four fibers were perfused with a non-caffeinated Ringer's solution, while the other four fibers were perfused with a caffeinated (70 microM) Ringer's solution.
The order was reversed for the second contractile period. The single myofibers were stimulated during each contractile period at increasing frequencies (0.16, 0.20, 0.25, 0.33, 0.50, and 1.0 tetanic contractions/second) with each stimulation frequency lasting 2 minutes until fatigue ensued, defined in this study as a fall in tension development to 66% of maximum. Tension development and free cytosolic [Ca(2+)] (fura-2 fluorescence spectroscopy) were simultaneously measured. There was no significant difference in the peak force generation, time to fatigue, cytosolic Ca(2+) levels, or relaxation times between the non-caffeinated and caffeinated trials.
CONCLUSION: These results demonstrate that physiological levels of caffeine have no significant effect on Xenopus single myofiber contractility, Ca(2+) handling, and fatigue development and suggest that that any ergogenic effects of physiological levels of caffeine on muscle performance during contractions of moderate-to-high intensity are likely related to factors extraneous to the muscle fiber.
My Notes: While readers of this blog will be quick to point out that this was a highly isolated study done in a dish, the cool part is that you can isolate some interesting things. Having said that, this is a very crude study and I am scratching my head at what was novel here? How is this new in 2009?
For those that are wondering, it is a type of frog; although classically many of the early experiments on the neuromuscular junction (NMJ) were done in a similar set up. Heck, I took a whole class where we did this and the crazy set up to the experiment may take you 2-3 hours BEFORE you measure anything.
The newer researcher shows that the main effect of caffeine is central nervous system related (CNS). I am still amazed at how much we don't know about the mechanisms of caffeine, even though it has been studied for quite some time.
