BackgroundResearch has indicated that low-to-moderate dosages of caffeine supplementation are ergogenic for sustained endurance efforts as well as high-intensity exercise. The effects of caffeine supplementation on strength-power performance are equivocal, with some studies indicating a benefit and others demonstrating no change in performance. The majority of research that has examined the effects of caffeine supplementation on strength-power performance has been carried out in both trained and untrained men. Therefore, the purpose of this study was to determine the acute effects of caffeine supplementation on strength and muscular endurance in resistance-trained women.MethodsIn a randomized manner, 15 women consumed caffeine (6 mg/kg) or placebo (PL) seven days apart. Sixty min following supplementation, participants performed a one-repetition maximum (1RM) barbell bench press test and repetitions to failure at 60% of 1RM. Heart rate (HR) and blood pressure (BP) were assessed at rest, 60 minutes post-consumption, and immediately following completion of repetitions to failure.ResultsRepeated measures ANOVA indicated a significantly greater bench press maximum with caffeine (p ≤ 0.05) (52.9 ± 11.1 kg vs. 52.1 ± 11.7 kg) with no significant differences between conditions in 60% 1RM repetitions (p = 0.81). Systolic blood pressure was significantly greater post-exercise, with caffeine (p < 0.05) (116.8 ± 5.3 mmHg vs. 112.9 ± 4.9 mmHg).ConclusionsThese findings indicate a moderate dose of caffeine may be sufficient for enhancing strength performance in resistance-trained women.

The purpose of this study was to examine the effects of different durations of static stretching on dynamic balance. Women (N = 28) were tested before and after 2 stretching interventions and a control condition on 3 separate days, at least 48 hours apart. The stretching sessions involved a cycle ergometer warm-up at 70 rpm and 70 W followed by passive stretching of the lower-body muscles. Each stretching position was held at a point of mild discomfort and repeated 3 times with 15 seconds between stretches. In the 2 stretching protocols, the positions were maintained for 15 or 45 seconds. The control condition involved the same cycle ergometer warm-up, with a 26-minute rest period between pre- and posttests. Balance was assessed using the Biodex Balance System. A 2-way repeated-measures analysis of variance was used with the effects of study condition (control, 15 seconds, 45 seconds) and time (pre-, postscores). Post hoc paired t-tests were used when appropriate to determine possible statistical significance between pre- and posttest scores. Analyses indicated no significant main effects for either study condition or time. However, there was a significant condition x time interaction (p < 0.05). Post hoc analyses indicated that the 15-second condition produced a significant improvement in the balance scores (p < 0.01), with no significant effects with the control condition or the 45-second treatment. The results of this study reveal that a stretching protocol of 45-second hold durations does not adversely affect balance when using the current stabilometry testing procedure. Furthermore, a stretching intervention with 15-second hold durations may improve balance performance by decreasing postural instability. Strength and conditioning professionals concerned with reported performance limitations associated with static stretching should consider applying shorter-duration stretching protocols when aiming to improve balance performance.

Exercise on an isokinetic device involves three primary components (12,17) : acceleration, sustained velocity, and deceleration. Acceleration is popularly defined in the literature as an individual's ability to "catch" the dynamometer (5,ll). The "catch" results as velocity is attained, and resistance is encountered to restrict further acceleration. Free limb acceleration experiences no external machine resistance, yet encounters resistance through the weight of the limb and the dynamometer attachment and the inertial torques caused by acceleration of their masses. Mechanical deceleration, as opposed to an antagonistic muscle eccentric contraction, offers resistance while the dynamometer decreases speed, yet it ceases to be isokinetic and is not directly governed by the clinician nor . -quantifiable as torque produced under controlled isokinetic conditions. Therefore, since machine-offered resistance during exercise on an isoki--netic dynamometer requires velocity attainment, it follows that the potential for strength gains from such an exercise, via muscular overload, may be proportional to the total amount of range of motion (ROM) actually sustained at the predetermined isdki-

This study determines the effects of short-term isokinetic training on rate of velocity development (RVD) and force. Three groups were pre- and posttested for knee extension RVD and force at 1.04 (slow) and 4.18 rad.s(-1) (fast) on a Kin-Com dynamometer. The slow and fast groups completed 2 days of velocity-specific training, whereas the control group did not train. Four-way analysis of variance results demonstrated significant (p < 0.05) decreases in RVD between pre- and posttests for the slow group at the slow velocity (RVD-1.25 +/- 0.04 degrees vs. 1.08 +/- 0.03 degrees ) and for the fast group at the fast velocity (RVD-14.24 +/- 0.33 degrees vs. 13.59 +/- 0.29 degrees ). Force exhibited no significant differences between testing days for any group. These results demonstrate that short-term isokinetic training results in velocity-specific RVD improvements. These acute RVD improvements may serve to offset strength deficits in power environments on the basis of the mutable relationship between force and velocity.