Water is an essential nutrient for all persons; thus, maintaining a chronic state of optimal hydration is recognized to provide health benefits. Fluid balance is maintained via thirst, a feedback-controlled variable, regulated acutely by central and peripheral mechanisms. However, voluntary drinking is also a behavior influenced by numerous social and psychological cues. Therefore, whether "thirst-guided" drinking maintains optimal hydration status is a multifactorial issue. Thirst perception is typically assessed by subjective ratings using either categorical or visual analog scales; however, which instrument yields greater sensitivity to change in hydration status has not been examined. Ratings of thirst perception do not always yield predictable patterns of voluntary drinking following dehydration; therefore, perceived thirst and ad libitum drinking are not equivalent measures of human thirst. The recommendation "drink to thirst" is frequently given to healthy individuals during daily life. However, factors and conditions (e.g., age, disease) that influence thirst should be recognized and probed further.

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Research has demonstrated that caffeine ingestion improves physical performance. Caffeinated chewing gum is commercially available for consumption and the use of such products to enhance cycling performance may appeal to competitive cyclists. Stay Alert™ chewing gum (100mg caffeine/piece) offers a quick and effective delivery of caffeine via the buccal mucosa. PURPOSE:The purpose of the current investigation was twofold: 1) to determine if caffeine administered in chewing gum (Stay Alert™) enhances cycling performance, 2) to identify whether timing of administration impacts subsequent performance. METHODS:Eight male cyclists participated in five separate laboratory sessions, with a one week washout period between sessions. During the first visit, subjects underwent a graded exercise test on an Excalibur 1300Wcycle ergometer to determine maximal oxygen consumption (VO2max) and were allotted time to practice the cycle time trial (TT). For each of the next four visits, 3 pieces of chewing gum [caffeine (CAFF) or placebo (PLA)] were administered at 3 time points, 120 min pre exercise (-120), 60 min pre exercise (-60), and 5 min pre exercise (-5). In 3 of the 4 experimental trials, CAFF was administered at one of the three time points and PLA at the other two time points. During the control trial (CON), PLA gum was administered at all three time points. The order in which participants completed the experimental trials was randomized. Following baseline measurements, time allotted for gum administration, and a standard warmup, participants cycled at 75% VO2max (constant Wattage) for 15 min then completed a 7 kj·kg -1 TT.) or PL ingestion 1h prior to the trial (counterbalanced). Exercises were performed to failure (2 minutes recovery between sets/exercises). RPE (0-10 Omni scale) was recorded after every set and Session-RPE (S-RPE) was recorded 20min after each trial. RESULTS:For total repetitions, a 2 (trial) x 4 (sets) repeated measures ANOVA revealed a significant difference for bench press (p=0.02) but no not for lat pulldown, shoulder press, bicep curl, tricep pushdown, or leg press (CA vs. PL). CA resulted in a non-significant (p=0.24) 1.7% increase in total repetitions for all exercises (CA 2111 ± 2, PL 2076 ± 2) and sets combined compared to PL. Post-hoc analyses revealed significantly greater repetitions (p=0.003) for bench press (set 4) and approached significant (p=0.06) for shoulder press (set 1) with CA. However, no significant difference was found for any other set (p>0.05). No significant difference was shown for RPE (p>0.05) or S-RPE (p=0.44) with CA (8.1 ± 0.8) vs. PL (7.9 ± 0.9). Three participants exceeded the effect size for total repetitions (>20 reps) showing a 10-18% improvement with CA. Other participants showed no response (n=4) or a decrement (n=3) in performance with CA. CONCLUSIONS:Results indicate CA may influence resistance training performance but is highly variable among subjects. More research is needed to clarify reasons for deviant individual responses.