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C O R R E S P O N D E N C E

Authors Reply to Periard: Cardiovascular DeterminantsInvolved in Pacing Under Heat Stress

The Complex Skill of Pacing: Is There an Interplay Between Central and Peripheral

Determinants?

B. Roelands J. de Koning C. Foster

F. Hettinga R. Meeusen

Published online: 9 May 2013

Springer International Publishing Switzerland 2013

By posing the question we already give the answer: the

time has passed when exercise physiologists divided thehuman body into a heart and muscles and the mysterious

brain. Exercise physiology integrates both and pacing is a

very nice example of the interplay between peripheral

factors including cardiovascular regulation, metabolism,

muscle physiology, and central factors such as neuro-

transmission, perception of effort, control of thermoregu-

lation, and others [1, 2]. We therefore thank Dr Periard for

his feedback [3] on our article and for pointing out the

importance of cardiovascular limitations during prolonged

exercise [4]. Indeed, cardiovascular limitations induced by

adjustments in thermoregulation can significantly influence

the maintenance of a given absolute intensity or pace, as

was stated by Periard. Evidence from studies in our labo-

ratory [57] showed that fixed-intensity exercise (60 min at55 % of the maximal power output) resulted in signifi-

cantly higher heart rates in hot conditions (30 C) when

compared with normal (18 C) ambient temperature.

Unfortunately, we did not measure stroke volume, cardiac

output, or blood flow as was done in the study by Periard

et al. [4] and that would have provided interesting infor-

mation. During the 30-min time trial that followed the

60-min fixed-intensity exercise, the observed difference in

heart rate disappeared. This could be explained by the

attainment of higher power outputs in normal conditions

compared with hot ambient conditions. Furthermore, from

10 min to the termination of exercise, heart rates followed

a similar pattern in both conditions. This outcome is not

identical to the findings of Periard et al. [4] but again

emphasizes the interplay between peripheral and central

aspects in pacing. Generally, these data demonstrate that

the cardiovascular system is a coinfluencer of exercise

performance (and thus pacing strategy) that cannot be

overlooked. The data also encourage scientists to further

unravel the mechanisms behind changes in pace and the

onset of fatigue, certainly during prolonged exercise bouts

in the heat.

In our review, we acknowledged the complexity of the

concept of pacing, and consequently the interplay between

peripheral and central factors. However, our main area of

expertise lies in the central aspects of fatigue and the

manipulation of brain neurotransmission in different ambient

settings [8]. Our review was therefore focused on the

central aspects of exercise in the heat, an area that has

gained more importance in the recent years. Furthermore, in

our article we directed interested readers to the excellent

review by Abbiss and Laursen [2], who described nine dif-

ferent models of fatigue, including the cardiovascular model.

This reply refers to the comment available at

doi:10.1007/s40279-013-0050-0.

B. Roelands R. Meeusen (&)

Department of Human Physiology, Faculty of Physical

Education and Physiotherapy, Vrije Universiteit Brussel,

Brussels, Belgium

e-mail: rmeeusen@vub.ac.be

B. Roelands

Fund for Scientific Research Flanders (FWO), Brussels, Belgium

J. de Koning C. Foster

Research Institute MOVE, Faculty of Human Movement

Sciences, VU University, Amsterdam, The Netherlands

J. de Koning C. Foster

Department of Exercise and Sport Science, University of

Wisconsin, La Crosse, USA

F. Hettinga

University of Groningen, University Medical Center Groningen,

Center of Human Movement Sciences, Groningen,

The Netherlands

Sports Med (2013) 43:647648

DOI 10.1007/s40279-013-0051-z

http://dx.doi.org/10.1007/s40279-013-0050-0http://dx.doi.org/10.1007/s40279-013-0050-0

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In conclusion, we feel that the letter written by Dr.

Periard clearly underlines the need for further research and

emphasis on how fatigue and pacing are surely not a

peripheral or central entity but rather a peripheral and

central phenomenon.

Acknowledgements Bart Roelands is a post-doctoral fellow of the

Fund for Scientific Research Flanders (FWO). The authors have noconflicts of interest that are directly relevant to the content of this

letter.

References

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determinants of theoretical concepts and mechanisms involved in

pacing. Sports Med. 2013;43(5):30111. doi:10.1007/s40279-013-

0030-4.

2. Abbiss CR, Laursen PB. Models to explain fatigue during

prolonged endurance cycling. Sports Med. 2005;35(10):86598.

3. Periard JD. Cardiovascular determinants involved in pacing under

heat stress (letter). 2013. doi:10.1007/s40279-013-0050-0.

4. Periard JD, Cramer MN, Chapman PG, et al. Cardiovascular strain

impairs prolonged self-paced exercise in the heat. Exp Physiol.

2011;96(2):13444.

5. Roelands B, Hasegawa H, Watson P, et al. The effects of acute

dopamine reuptake inhibition on performance. Med Sci Sports

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