Abstracts / Journal of Science and Medicine in Sport 12S (2009) S1–S83 S29 carbohydrate, 20% fat and 13% protein. There was a trend for female participants to consume greater masses of food and drink relative to body weight prior to the event. Slower and younger participants tended to consume meals of higher fat and protein content. With regard to the timing of the pre-event meal, 35% of respondents ingested food or drink in the hour before the event, 35% 1–2 h before, and 79% after waking but more than 2h before the event. During the event, par- ticipants received on average 2.4 (0–14) cups of fluid, with sports drinks being twice as popular as water. There was a trend for younger and slower participants to receive more cups of fluid during the event than faster and older partici- pants. Twenty-five percent of respondents consumed no fluid during the event. Conclusions: The results of the study indi- cate that the pre-event nutrition of participants was mostly consistent with the provided guidelines but there is extreme variability in the practices of individuals. There is a need for intra-event fluid consumption to be further encouraged. doi:10.1016/j.jsams.2008.12.066 66 Application of the ACSM guidelines for fluid and carbo- hydrate replacement to a 90 min indoor group ‘aerobics’ session D. Morton Avondale College, Australia Purpose: The ACSM recommends that for exercise exceeding one hour, individuals can benefit from consuming a 4–8% carbohydrate solution at a rate of 600–1200 mL/h. The purpose of this study was to evaluate these guidelines in the context of an indoor group ‘aerobics’ session. Meth- ods: Nineteen individuals (6 males/13 females) participated in three 90 min group ‘aerobic’ sessions (-80% HRmax) during which they consumed no fluid, flavoured water (0 car- bohydrate) or an 8% CHO solution (Powerade ® ), at a rate of 900 mL/h (total = 1350 mL). Results: The subjects incurred greater fluid losses (p = 0.00) when they consumed water (1.00 + 0.28 L) or Powerade ® (1.09 ± 0.32 L) as compared to no fluid (0.75 ± 0.31 L), mostly as a consequence of greater (p = 0.00) urine production. Sweat production was lower in the no fluid trial (0.62 + 0.23 L) than the Powerade ® trial (0.77 + 0.24 L, p = 0.02), but no different from the water trial (0.69 + 0.25 L, p = 0.25). There was a trend for the Powerade ® to cause a smaller rise in heart rate throughout the session (p = 0.08) but the increase in the rating of perceived exertion was similar for all trials (p = 0.49). No trial recorded signif- icant or dangerous rises in core temperature. The trials in which fluid was consumed were no more provocative of gas- trointestinal symptoms including burping, reflux, nausea and bloating. There was a trend (p = 0.07) towards fewer symp- toms of ‘stitch’ when no fluid was consumed. Conclusions: Consuming water or a carbohydrate solution according to the ACSM guidelines did not appear to provide clear benefits or disadvantages during a 90 min group ‘aerobics’ session performed in a temperate indoor environment. doi:10.1016/j.jsams.2008.12.067 67 Optimization of the sensor monitoring software in a respi- ratory gas analysis system for high-performance athletes Y. Lin Australian National University, Australia Most respiratory gas analysis systems assume complete and stable drying of the expired air from an athlete prior to analysis of O 2 and C0 2 without direct measurement of this important parameter. In this paper, the author sum- marises a programmed monitoring application to quantify the effectiveness of a two-stage dryer within an expired air gas analysis system for athletes. The user-friendly, custom software alerts users to abnormal performance or failure of the temperature/humidity sensors. Combining USB-serial ports communication, real-time visualization of data, and the integrated temperature/humidity alarm system, the newly developed analysis system provides user confidence that the moisture content of the gases being analysed for the frac- tion of 0 2 and C0 2 are not excessively affected by moisture, which will spuriously dilute the partial pressure of these gases and cause erroneous values for oxygen consumption and/or carbon dioxide production. Written in standard C++ language and compatible with Windows software, the appli- cation is flexible and expandable, and consequently can be readily updated to suit other working environments and fur- ther research using multiple sensors. The efficiency and stability of the application was verified by debugging and running in the real working environment. doi:10.1016/j.jsams.2008.12.068 68 Deriving upper arm rotation from Vicon to enhance the first serve in tennis A. Ahmadi 1,2,∗ , D. Rowlands 1 , D. James 1,2 1 Centre of Wireless Monitoring Applications, Griffith University, Australia 2 Centre of Excellence, Queensland Academy of Sport, Australia Introduction: Upper arm rotation is a major contributor (>53%) to the speed of a first serve in tennis. Monitoring this rotation using standard models in marker-based systems is problematic. In this paper we present a vector-based method using Vicon’s standard plug-in-gait together with geomet- ric calculations and a mapping of the space to calculate