We have hypothesized: 1) Caffeine will increase maximal voluntary strength compared to
placebo in undamaged muscle. 2) Caffeine will increase muscle activation compared to placebo
in undamaged muscle. 3) Caffeine will enhance spinal excitability (indicated by an enhanced
H-reflex) compared to placebo in undamaged muscle. 4) Caffeine will raise the pressure-pain
threshold (indicating decreased pain sensitivity) in the calf muscle compared to placebo in
undamaged muscle. 5) Caffeine will reduce the amount of low-frequency fatigue, indicated by
an enhanced 20-100 hertz strength ratio, compared to placebo in undamaged muscle. 6) Caffeine
will increase maximal voluntary strength compared to placebo in damaged muscle. 7) Caffeine
will increase muscle activation compared to placebo in damaged muscle. 8) Caffeine will
enhance spinal excitability (indicated by an enhanced H-reflex) compared to placebo in
damaged muscle. 9) Caffeine will raise the pressure-pain threshold (indicating decreased pain
sensitivity) in the calf muscle compared to placebo in damaged muscle. 10) Caffeine will
reduce the amount of low-frequency fatigue, indicated by an enhanced 20-100 hertz strength
ratio, compared to placebo in damaged muscle.
The proposed research will determine the effects of a 5mg/kg body weight dose of caffeine on
muscular strength, activation, H-reflex function, and excitation-contraction coupling before
and after exercise-induced muscle damage. The long term objectives are to gain a better
understanding of caffeine and its affects following exercise-induced muscle damage allowing
us to understand how caffeine is mechanistically interacting with functions of the body.