european college of sport science

Saturday, June 27th, 2009
08:30 - 10:00
Oral presentations
OP-PH12 Physiology 12
EFFECT OF CAFFEINE INGESTION DURING PROLONGED EXHAUSTIVE EXERCISE ON SALIVARY IMMUNOGLOBULIN A,
Α-AMYLASE AND CORTISOL
ALLGROVE, J., OLIVEIRA, M., SILVER, B., GLEESON, M.
UNIVERSITY OF GREENWICH AT MEDWAY
Exercise can have deleterious effects on the secretion of salivary immunoglobulin A (s-IgA), which appears to be related to perturbations
in sympatheticoadrenal activation (Teeuw et al., 2004). Caffeine, commonly used for its ergogenic properties is associated with increased
sympathetic nervous system activity, and it has been previously shown that caffeine ingestion before intensive cycling enhances s-IgA
responses during exercise (Bishop et al., 2006). Therefore, the aim of the present study was to examine the effect of a performance cereal
bar, containing caffeine, before and during prolonged exhaustive cycling on exercise performance and the salivary secretion of IgA, αamylase
activity and cortisol. Using a randomised cross-over design and following a 10 – 12 hour overnight fast, 12 trained cyclists, mean
(SEM) age: 21(1) yr; height: 179(2) cm; body mass: 73.6(2.5) kg; maximal oxygen uptake, VO2max: 57.9(1.2) completed 2.5 h of cycling at
60%VO2max (with regular water ingestion) on a stationary ergometer, which was followed by a ride to exhaustion at 75% VO2max.
Immediately before exercise, and after 55 min and 115 min of exercise participants ingested a 0.9 MJ cereal bar containing 45 g carbohydrate,
5 g protein, 3 g fat and 100 mg of caffeine (CAF) or an isocaloric noncaffeine bar (PLA). Unstimulated timed saliva samples were
collected immediately before exercise, after 70 min and 130 min of exercise, and immediately after the exhaustive exercise bout. Saliva
was analysed for s-IgA, α-amylase activity and cortisol concentration. Saliva flow rates were determined to calculate the s-IgA secretion
rate. Data were analysed using a 2-way repeated measures ANOVA and post-hoc t-tests with Holm Bonferroni adjustments applied
where appropriate. Time to exhaustion was 35% longer in CAF compared with PLA ((2177 (0.2) vs 1615 (0.16) s; P < 0.05)). Saliva flow rate
did not change significantly during the exercise protocol. Exercise was associated with elevations in s-IgA concentration (9% increase), s-
IgA secretion rate (24% increase) and α-amylase activity (224% increase) post-exhaustion (P < 0.01), but there was no effect of CAF on
these responses. Salivary cortisol concentration increased by 64% post-exhaustion in the CAF trial only (P < 0.05), indicating an increase
in adrenal activity following caffeine ingestion. Values were 35.7 (5.5) and 19.6 (3.4) nmol/L post-exhaustion for CAF and PLA, respectively.
These findings show that ingestion of a caffeine containing cereal bar during prolonged exhaustive cycling enhances endurance performance,
increases salivary cortisol secretion post-exhaustion, but does not affect the exercise-induced increases in s-IgA or α-amylase
activity.
Bishop et al. (2006) Medicine and Science in Sports and Exercise, 38: 513-519
Teeuw et al. (2004) Biological Chemistry. 385:1137-1146
ESTIMATING THE TIME DEPENDENCY OF THE DEMAND IN RESPONSE TO AND RECOVERY FROM HEAVY EXERCISE
STIRLING, J., ZAKYNTHINAKI, M.S.
UNIVERSIDAD POLITECNICA DE MADRID
Introduction: The problem of estimating the time dependency of the physiological demand in response to exercise is a fundamental
problem in exercise physiology, where the lack of appropriate tools and techniques forces the assumption of a constant demand during
heavy exercise. Models such as those developed by (Stirling et al, 2008a, 2008b, 2005) based on methods from nonlinear dynamical
systems use such information when modeling the oxygen uptake and heart rate kinetics. The aim of this study is to apply the ALOPEX IV
stochastic optimization method to estimate the heart rate demand in response to and in recovery from various heavy exercise intensities
(Zakynthinaki and Stirling, 2008).
Methods: Beat to beat heart rate data were obtained from an athlete who performed a series of bouts of exercise at different constant
intensities. The optimal fit of the heart rate model to the basic response pattern (Zakynthinaki et al, 2007) of the raw un averaged data for
low exercise intensities was obtained used the stochastic optimization algorithm (Zakynthinaki and Stirling, 2007). The model was then fit
to heavy exercise intensities by the use of an appropriate partition of the physiological time series and by means of stochastic optimization
Zakynthinaki and Stirling (2008). This enabled us to estimate the time dependency of the heart rate demand for heavy intensity exercise
and its subsequent recovery.
Results: For the first time the demand of the heart rate as a function of time was found for a heavy constant exercise intensity and the
subsequent recovery. It was observed that time dependency of this demand was very different from the constant demand assumption.
Discussion: A method for estimating the demand in response to heavy constant intensity exercises was shown to provide new previously
unobtainable information regarding the time dependent nature of the demand. This method was applied to the heart rate, however the
method is equally as applicable to oxygen uptake kinetics and hence has many possible applications both in fundamental exercise
physiology, medicine and sport.
References
Stirling JR and Zakynthinaki MS, (2008) J Nonlin Math Phys 15(sup3), 396-403..
Stirling JR, Zakynthinaki MS, Sampedro J and Refoyo I (2008a) J Nonlin Math Phys. 15(sup3), 426-436.
Stirling JR, Zakynthinaki MS and Billat VL, (2008b) Bul. Math. Biol, 70(5):1348-1370.
Stirling JR, Zakynthinaki MS, Saltin B, (2005) Bul. Math. Biol. 67(5), 989-1015.
Zakynthinaki MS, Stirling JR, (2008). Comp Phys Comm, 179(12), 888-894.
Zakynthinaki MS, Stirling JR, Sillero M, Sampedro J, Refoyo I, Materials Matematics, UAB (2007).
Zakynthinaki MS, Stirling JR, (2007) Comp. Phys. Commun. 176(2), 98-108.
OSLO/NORWAY, JUNE 24-27, 2009 503