Nancy N. Thompson

Effect of pacing strategy on cycle time trial performance.

Despite interest in competitive strategy by coaches and athletes, there are no systematically collected data regarding the effect of differences in pacing strategy on the outcome of middle distance (2-4 min duration) events. In this study different pacing strategies were evaluated using a 2-km time trial on a bicycle attached to a wind load simulator. Well-trained subjects (N = 9) performed five separate time trials with the pace during the first 50% of the trial experimentally constrained within the usual real world range from very slow (approximately 55% of best time) to very fast (approximately 48% of best time). Serial VO2 was measured to estimate the oxidative contributions to the trial and accumulated O2 deficit and postexercise blood lactate measured to estimate the anaerobic contribution to the trial. The evenly paced trial (first 1 km = 50.9% final time) produced the fastest total time. The starting pace to final time relationship was described by a U shaped second order polynomial curve with the nadir for final time at a starting pace of 51% of best total time. There were no systematic differences in serial VO2, accumulated O2 deficit, or postexercise lactate that could account for the pacing related variations in performance. The data support the concept of relatively even pacing in middle distance events with negative consequences for even small variations in this strategy.

Physiological responses during simulated competition.

Laboratory studies with competitive athletes often use graded exercise protocols to elicit physiologic responses. This pattern of power output is different than ordinarily employed by athletes during competition. To understand the physiologic responses during competition, we studied 24 athletes (speed skaters, cyclists, triathletes) during simulated competition, a 5-km time trial on a racing bicycle attached to a windload simulator, and during cycle ergometer graded exercise testing (N = 8). During the time trial the velocity pattern was similar to real world competitions, and the subjects indicated that the time trial was perceptually similar to competition. Physiologic responses were of significantly greater magnitude vs graded exercise (VO2max: 3.46 +/- 0.73 vs 3.27 +/- 0.79 l.min-1; VEmax: 138 +/- 27 vs 119 +/- 22 l.min-1; HRmax 184 +/- 11 vs 175 +/- 11 beats x min-1; HLa 14.8 +/- 3.7 vs 11.9 +/- 2.1 mM). All physiologic measures increased steadily throughout the time trial (km 0, 1, 2, 3, 4, and 5: VO2 = 1.03, 2.95, 3.42, 3.69, 3.82, and 3.92 l.min-1; HR = 93, 175, 181, 185, 189, and 194 beats.min-1; VE = 31, 99, 120, 129, 145, and 156 l.min-1; HLa = 2.9, 5.6, 7.2, 9.2, 10.6, and 13.5 mM). In six subjects (speed skaters), the peak values observed during time trial for HR (188 +/- 6 vs 191 +/- 5 beats.min-1) and HLa (16.4 +/- 3.1 vs 17.0 +/- 4.2 mM) were not significantly different than observed during real world competition.(ABSTRACT TRUNCATED AT 250 WORDS)

Predicting functional capacity during treadmill testing independent of exercise protocol.

Clinically useful estimates of VO2max from treadmill tests (GXT) may be made using protocol-specific equations. In many cases, GXT may proceed more effectively if the clinician is free to adjust speed and grade independent of a specific protocol. We sought to determine whether VO2max could be predicted from the estimated steady-state VO2 of the terminal exercise stage. Seventy clinically stable individuals performed GXT with direct measurement of VO2. Exercise was incremented each minute to optimize clinical examination. Measured VO2max was compared to the estimated steady-state VO2 of the terminal stage based on ACSM equations. Equations for walking or running were used based on the patients observed method of ambulation. The measured VO2max was always less than the ACSM estimate, with a regular relationship between measured and estimated VO2max. No handrail support: VO2max = 0.869.ACSM -0.07; R2 = 0.955, SEE = 4.8 ml.min-1.kg-1 (N = 30). With handrail support: VO2max = 0.694.ACSM + 3.33; R2 = 0.833, SEE = 4.4 ml.min-1.kg-1 (N = 40). The equations were cross-validated with 20 patients. The correlation between predicted and observed values was r = 0.98 and 0.97 without and with handrail support, respectively. The mean absolute prediction error (3.1 and 4.1 ml.min-1.kg-1) were similar to protocol-specific equations. We conclude that VO2max can be predicted independent of treadmill protocol with approximately the same error as protocol-specific equations.

Prediction of Functional Capacity During Treadmill Testing: Effect of Handrail Support

McConnell and Clark (1987) and Foster et al. (1984) have developed equations for predicting functional capacity (VO2peak) from maximal treadmill performance. McConnell investigated the effects of handrail support (HHR). while Foster did not allow HRS. On the basis of the known reduction in the aerob

Functional Translation of Exercise Responses during Combined Arm-Leg Ergometry

Previous studies have shown that the absolute power output required to produce a desired training heart rate could be predicted from the power output-heart rate relationship during exercise testing. The intent of this study was to develop an equation for the functional translation of exercise responses using combined arm-leg ergometry. Volunteer subjects (n = 16) performed exercise testing and three, 20-min exercise training sessions at different intensities on the combined arm-leg ergometer. Power output during exercise testing and training were well related (r = 0.905) with a small standard error estimate (12.1 W). Cross-validation of the regression equation developed from the validation sample yielded a high correlation (r = 0.969) with no differences between predicted and observed training heart rates.

Functional translation of exercise responses from graded exercise testing to exercise training

This study attempts to develop a quantitative approach to the prescription of absolute exercise intensity during level ground ambulation (min/mile) or cycle ergometry (kpm) from responses observed during GXT. A total of 345 subjects performed GXT and exercise training sessions with either the Bruce treadmill protocol and level ground ambulation (N = 154) or cycle ergometry (N = 191). Responses from 90% of each group were used to generate equations for predicting training pace (or power output) from the time (or power output) during the GXT when target HR was achieved. FAI was also included in the prediction of training pace (or power output). The remaining 10% of subjects in each group were used to cross-validate the prediction equations. The correlation between the time (or power output) during GXT when the training HR was observed and the pace of ambulation (or power output) was 0.70 for treadmill walking and 0.88 for cycle-cycle. Correlations were increased by the addition of FAI to the prediction equation. The results of this investigation suggest that the absolute intensity of exercise for training can be predicted accurately from GXT results.

Serial gastric emptying studies: effect of preceding drinks.

A widely used method for evaluating gastric emptying is the serial recovery method, in which several different test drinks are given and recovered in rapid succession. Recently, the validity of this method has been challenged (Brouns et al., Int. J. Sports Med. 8:175-189, 1987) by suggestions that the duodenal contents remaining from previous drinks may influence the gastric emptying of subsequent drinks. To evaluate whether this methodological issue might influence the results of gastric emptying studies, we studied six volunteer subjects. The gastric emptying rate of water was measured following a previous trial with either water or a concentrated maltodextrin solution (23% CHO). All trials were conducted at rest and consisted of a volume of 400 ml. The emptying rate of water was not different following either water or maltodextrin solution (14.9 vs 16.3 ml.min-1). We conclude that the serial recovery method remains a valid technique for measuring the rate of gastric emptying during rest and exercise.

Menstrual function in elite speed skaters

Twenty‐three female members of the United States Speed Skating Team were evaluated and followed during four years of preparation for the 1988 Olympic Winter Games. Those skaters who reported having prolonged inter‐menstrual intervals had the highest average menarcheal age of 14.2 years. This was significantly older than the average menarcheal age of 13 years among skaters who did not report menstrual disruption. Skaters who began intense training in late childhood tended to later menarche and prolonged intermenstrual intervals when compared with skaters who initiated their training earlier, but these differences did not reach statistical significance. Menstrual disruption in subjects during the course of these observations was unusual; although many skaters reached very high levels of training and those who were involved in pre‐Olympic competitions achieved extremely low proportions of body fat content.

FUNCTIONAL TRANSLATION OF EXERCISE RESPONSES FROM GRADED EXERCISE TESTING TO EXERCISE TRAINING USING CYCLE ERGOMETRY

This study attempts to develop a quantitative approach to the prescription of absolute exercise intensity during level ground ambulation (min/mile) or cycle ergometry (kpm) from responses observed during GXT. A total of 345 subjects performed GXT and exercise training sessions with either the Bruce treadmill protocol and level ground ambulation (N = 154) or cycle ergometry (N = 191). Responses from 90% of each group were used to generate equations for predicting training pace (or power output) from the time (or power output) during the GXT when target HR was achieved. FAI was also included in the prediction of training pace (or power output). The remaining 10% of subjects in each group were used to cross-validate the prediction equations. The correlation between the time (or power output) during GXT when the training HR was observed and the pace of ambulation (or power output) was 0.70 for treadmill walking and 0.88 for cycle-cycle. Correlations were increased by the addition of FAI to the prediction equation. The results of this investigation suggest that the absolute intensity of exercise for training can be predicted accurately from GXT results.