Exercise testing remains a remarkably durable and versatile tool that provides valuable diagnostic and prognostic information regarding patients with cardiovascular and pulmonary disease. Exercise testing has been available for more than a half century and, like many other cardiovascular procedures, has evolved in its technology and scope. When combined with exercise testing, adjunctive imaging modalities offer greater diagnostic accuracy, additional information regarding cardiac structure and function, and additional prognostic information. Similarly, the addition of ventilatory gas exchange measurements during exercise testing provides a wide array of unique and clinically useful incremental information that heretofore has been poorly understood and underutilized by the practicing clinician. The reasons for this are many and include the requirement for additional equipment (cardiopulmonary exercise testing [CPX] systems), personnel who are proficient in the administration and interpretation of these tests, limited or absence of training of cardiovascular specialists and limited training by pulmonary specialists in this technique, and the lack of understanding of the value of CPX by practicing clinicians.

Modern CPX systems allow for the analysis of gas exchange at rest, during exercise, and during recovery and yield breath-by-breath measures of oxygen uptake (Vo2), carbon dioxide output (Vco2), and ventilation (Ve). These advanced computerized systems provide both simple and complex analyses of these data that are easy to retrieve and store, which makes CPX available for widespread use. These data can be readily integrated with standard variables measured during exercise testing, including heart rate, blood pressure, work rate, electrocardiography findings, and symptoms, to provide a comprehensive assessment of exercise tolerance and exercise responses. CPX can even be performed with adjunctive imaging modalities for additional diagnostic assessment. Hence, CPX offers the clinician the ability to obtain a wealth of information beyond standard exercise electrocardiography testing that when appropriately applied and interpreted …

Clinician’s Guide to Cardiopulmonary Exercise Testing in Adults A Scientific Statement From the American Heart Association

QUITE apart from the academic consideration that vital and medical statistics now form an obligatory part of the education of students seeking the University of London's diploma in public health, the demand for information about the methods of vital and medical statistics is increasing. The most casual reader of the newspapers is now aware that population problems are of serious practical importance and that the publications of the General Register Office cannot be ignored. It is scarcely an exaggeration to say that the recently issued preliminary report on the census of 1931 is one of the most sensational documents which has appeared for years, and that he who reads it intelligently will understand what is meant by saying that civilisation is in the melting pot. An Introduction to Medical Statistics. By Hilda M. Woods William T. Russell. Pp. x + 125. (London: P. S. King and Son, Ltd., 1931.) 7s. 6d.

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An Introduction to Medical Statistics

Guidelines for Exercise Testing and Prescription

An athlete’s carbohydrate intake can be judged by whether total daily intake and the timing of consumption in relation to exercise maintain adequate carbohydrate substrate for the muscle and central nervous system (‘‘high carbohydrate availability’’) or whether carbohydrate fuel sources are limiting for the daily exercise programme (‘‘low carbohydrate availability’’). Carbohydrate availability is increased by consuming carbohydrate in the hours or days prior to the session, intake during exercise, and refuelling during recovery between sessions. This is important for the competition setting or for high-intensity training where optimal performance is desired. Carbohydrate intake during exercise should be scaled according to the characteristics of the event. During sustained high-intensity sports lasting *1 h, small amounts of carbohydrate, including even mouth-rinsing, enhance performance via central nervous system effects. While 30–60 g h 71 is an appropriate target for sports of longer duration, events42.5 h may benefit from higher intakes of up to 90 g h 71 . Products containing special blends of different carbohydrates may maximize absorption of carbohydrate at such high rates. In real life, athletes undertake training sessions with varying carbohydrate availability. Whether implementing additional ‘‘train-low’’ strategies to increase the training adaptation leads to enhanced performance in well-trained individuals is unclear.

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Carbohydrates for training and competition.

The purpose of this study was to evaluate the physical demands of English Football Association (FA) Premier League soccer of three different positional classifications (defender, midfielder and striker). Computerised time-motion video-analysis using the Bloomfield Movement Classification was undertaken on the purposeful movement (PM) performed by 55 players. Recognition of PM had a good inter-tester reliability strength of agreement (κ = 0.7277). Players spent 40.6 ± 10.0% of the match performing PM. Position had a significant influence on %PM time spent sprinting, running, shuffling, skipping and standing still (p 0.05). Players spent 48.7 ± 9.2% of PM time moving in a directly forward direction, 20.6 ± 6.8% not moving in any direction and the remainder of PM time moving backward, lateral, diagonal and arced directions. The players performed the equivalent of 726 ± 203 turns during the match; 609 ± 193 of these being of 0° to 90° to the left or right. Players were involved in the equivalent of 111 ± 77 on the ball movement activities per match with no significant differences between the positions for total involvement in on the ball activity (p > 0.05). This study has provided an indication of the different physical demands of different playing positions in FA Premier League match-play through assessment of movements performed by players.

Physical demands of different positions in FA Premier League soccer

PURPOSE AND METHOD: To investigate the possible role of carbohydrate (CHO) receptors in the mouth in influencing exercise performance, seven male and two female endurance cyclists (VO(2max) 63.2 +/- 2.7 (mean +/- SE) mL.kg*(-1).min(-1)) completed two performance trials in which they had to accomplish a set amount of work as quickly as possible (914 +/- 40 kJ). On one occasion a 6.4% maltodextrin solution (CHO) was rinsed around the mouth for every 12.5% of the trial completed. On the other occasion, water (PLA) was rinsed. Subjects were not allowed to swallow either the CHO solution or water, and each mouthful was spat out after a 5-s rinse. RESULTS: Performance time was significantly improved with CHO compared with PLA (59.57 +/- 1.50 min vs 61.37 +/- 1.56 min, respectively, P = 0.011). This improvement resulted in a significantly higher average power output during the CHO compared with the PLA trial (259 +/- 16 W and 252 +/- 16 W, respectively, P = 0.003). There were no differences in heart rate or rating of perceived exertion (RPE) between the two trials (P > 0.05). CONCLUSION: The results demonstrate that carbohydrate mouth rinse has a positive effect on 1-h time trial performance. The mechanism responsible for the improvement in high-intensity exercise performance with exogenous carbohydrate appears to involve an increase in central drive or motivation rather than having any metabolic cause. The nature and role of putative CHO receptors in the mouth warrants further investigation.

The effect of carbohydrate mouth rinse on 1-h cycle time trial performance

Telemetric gastrointestinal (GI) temperature pills are now commonly used to measure core body temperature and could minimize the risk of heat illness while maximizing operational effectiveness in workers subject to high levels of thermal strain.

Purpose: To quantify the effect of repeated cool water ingestion on the accuracy of GI pill temperature.

Methods: Ten operational firefighters ingested a pill to measure GI temperature (T1int) before overnight sleep. Two hours following breakfast and 11.5 h after ingesting T1int, the firefighters ingested a second pill (T2int) before performing 8.5 h of intermittent activity (repetitive cycles of 30 min of seated rest followed by 30 min of general firefighter duties). During the first 2 min of each 30-min rest period, the firefighters consumed 250 mL of chilled water (5-8[degrees]C).

Results: Water ingestion had a highly variable effect both within and between subjects in transiently (32 +/- 10 min) reducing the temperature of T2int in comparison with T1int. In general, this transient reduction in T2int became progressively smaller as time following ingestion increased. In some firefighters, the difference between T1int and T2int became negligible (+/- 0.1[degrees]C) after 3 h, whereas in two others, large differences (peaking at 2.0[degrees]C and 6.3[degrees]C) were still observed when water was consumed 8 h after pill ingestion.

Conclusion: These results show that a GI pill ingested immediately prior to physical activity cannot be used to measure core body temperature accurately in all individuals during the following 8 h when cool fluids are regularly ingested. This makes GI temperature measurement unsuitable for workers who respond to emergency deployments when regular fluid consumption is recommended operational practice.

The effect of cool water ingestion on gastrointestinal pill temperature.

Information concerning the validity and reliability of commercial on-line gas analysis systems is limited. The aim of this study was to provide a comparison of the validity and reliability of three on-line systems (Oxycon Alpha, Oxycon Pro and Pulmolab EX670) with that of Douglas bags. Two separate studies were conducted. In study 1, the three gas analysis systems were compared with Douglas bags using a metabolic simulator over four increases in ventilation. In study 2, ten subjects were split into equal groups exercising at 100 W or 150 W for 85 min on three separate occasions. Each system was used twice per visit. Study 1 demonstrated that the Oxycon Alpha and Douglas bags produced similar respiratory values over all levels of ventilation. The Oxycon Pro tended to slightly overestimate mean expiratory flow (V(E) ), oxygen uptake ( VO2), carbon dioxide production (VCO2) and respiratory exchange ratio (RER) at the higher ventilations. The Pulmolab produced large overestimations at all ventilations for and RER (up to 26.3% away from expectations), whilst values for, and were slightly underestimated at higher ventilations (up to 7.5% from expectations). The results of study 2 support the findings of study 1, with the Oxycon Pro and Oxycon Alpha producing similar results compared to Douglas bags for, and RER. The coefficients of variation for and measured using Douglas bags, Oxycon Pro and Oxycon Alpha were 3.3-5.1%, 4.7-7.0% and 4.5-6.3%, respectively, whilst that for the Pulmolab was highly variable (26.8-45.8%). The exercise study showed the Oxycon Pro and Oxycon Alpha to be both valid and reliable on-line systems for the measurement of parameters of respiration, at least at workloads up to 150 W.

Validity and reliability of three commercially available breath-by-breath respiratory systems

PURPOSE AND METHODS: To investigate the effect of glucose infusion on glucose kinetics and performance, six endurance cyclists (VO2max = 61.7 +/- 2.0 (mean +/- SE) mL x kg(-1) x min(-1)) completed two performance trials in which they had to accomplish a set amount of work as quickly as possible (991 +/- 41 kJ). Subjects were infused with either glucose (20% in saline; carbohydrate (CHO)) at a rate of 1 g x min(-1) or saline (0.9% saline; placebo (PLA)). It was hypothesized that time trial performance would be unaffected by the infusion of glucose, as endogenous stores of CHO would not be limiting in the PLA trial. RESULTS: Plasma glucose concentration increased from 4.8 +/- 0.1 mmol x L(-1) to 5.9 +/- 0.3 mmol x L(-1) during the PLA trial and from 4.9 +/- 0.1 mmol x L(-1) at rest to 12.4 +/- 1.1 mmol x L(-1) during the CHO trial. These values were significantly higher at all time points during the CHO trial compared with PLA (P < 0.001). In the final stages of the time trial, Rd in the PLA trial was 49 +/- 5 micromol x kg(-1) x min(-1) compared with 88 +/- 7 micromol x kg(-1) x min(-1) in the CHO trial (P < 0.05). Despite these differences, there was no difference in performance time between PLA and CHO (60.04 +/- 1.47 min, PLA, vs 59.90 +/- 1.49 min, CHO, respectively). Infused carbohydrate oxidation in the last 25% of the CHO trial was at least 675 +/- 120 micromol x kg(-1) and contributed 17 +/- 4% to total carbohydrate oxidation. CONCLUSION: The results demonstrate that glucose infusion had no effect on 1-h cycle time-trial performance, despite an increased availability of plasma glucose for oxidation and evidence of increased glucose uptake into the tissues.

The effect of glucose infusion on glucose kinetics during a 1-h time trial.

Sweat losses in team sports can be significant due to repeated bursts of high-intensity activity, as well as the large body size of athletes, equipment and uniform requirements, and environmental heat stress often present during training and competition. In this paper we aimed to: (1) describe sweat losses and fluid balance changes reported in team sport athletes, (2) review the literature assessing the impact of hypohydration on cognitive, technical, and physical performance in sports-specific studies, (3) briefly review the potential mechanisms by which hypohydration may impact team sport performance, and (4) discuss considerations for future directions. Significant hypohydration (mean body mass loss (BML) >2%) has been reported most consistently in soccer. Although American Football, rugby, basketball, tennis, and ice hockey have reported high sweating rates, fluid balance disturbances have generally been mild (mean BML <2%), suggesting that drinking opportunities were sufficient for most athletes to offset significant fluid losses. The effect of hydration status on team sport performance has been studied mostly in soccer, basketball, cricket, and baseball, with mixed results. Hypohydration typically impaired performance at higher levels of BML (3-4%) and when the method of dehydration involved heat stress. Increased subjective ratings of fatigue and perceived exertion consistently accompanied hypohydration and could explain, in part, the performance impairments reported in some studies. More research is needed to develop valid, reliable, and sensitive sport-specific protocols and should be used in future studies to determine the effects of hypohydration and modifying factors (e.g., age, sex, athlete caliber) on team sport performance.

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James M. Carter

Papers

The effect of carbohydrate mouth rinse on 1-h cycle time trial performance

The effect of cool water ingestion on gastrointestinal pill temperature.

Validity and reliability of three commercially available breath-by-breath respiratory systems

The effect of glucose infusion on glucose kinetics during a 1-h time trial.

Fluid Balance in Team Sport Athletes and the Effect of Hypohydration on Cognitive, Technical, and Physical Performance