Title

The Effects of Caffeine On Muscular Strength, Power, and Power-Endurance

Date of Award

1986

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Human Performance and Recreation

First Advisor

Tommy Boone

Advisor Department

Human Performance and Recreation

Abstract

The research was designed to study the effects of caffeine on the treatment variables of strength, power, and power-endurance as measured by a Cybex II Isokinetic Dynamometer. Sixteen weight trained individuals (mean age = 25.19 yrs, mean experience lifting weights = 76.13 months) were tested on the Cybex II on two occasions under the conditions of placebo (PBO) and 5 mg of caffeine (.) kg('-1) of body weight (CAF). Subjects refrained from caffeine usage 96 hours prior to the beginning of testing to eliminate the effects of caffeine tolerance. The study was double-blinded to prevent research bias. Significant differences (p (LESSTHEQ) .05) were found in the strength values obtained during five maximal knee extensions at 60(DEGREES) per second on the Cybex II. Strength values for the knee flexors were not significantly different. No significant differences in either the knee extensors or the knee flexors were found for peak power values obtained during 20 maximal repetitions at 240(DEGREES) per second on the Cybex II. Significant differences (p (LESSTHEQ) .05) were found when comparing total knee extensor power values during the last five repetitions of the 20 repetition test at 240(DEGREES) per second on the Cybex II. Data analysis indicated that caffeine potentiated greater strength values at slow speeds for the knee extensors but not for the knee flexors. Peak torque developed during high speed knee extensions and flexions were not significantly altered by caffeine. Caffeine did appear to have a sparing effect on total torque developed by the knee extensors during the last five repetitions of a 20 repetition, high-speed test. The same findings could not be duplicated for the knee flexors. Additional research is indicated to examine why there appears to be differences in the effects of caffeine on different muscle groups and on varying resistance speeds.