Speed ratio but cabin temperature positively correlated with increased heart rates among professional drivers during car races.
OBJECTIVE
The present study measures heart rate (HR) on a number of professional race-car drivers during actual car races through annual seasons to test hypotheses that faster relative speed and higher cabin temperature would induce higher HR.


METHODS
Heart rates in fifteen male drivers (31.2 ± 5.5 years old) were obtained by chest-strap sensors during official-professional 13 races. Average HR was calculated while the driver was racing from the start to the end of each race.


RESULTS
The average HR during races was 164.5 ± 15.1 beats min-1and the average amount of time each driver spent driving per race was 54.2 ± 13.7 min. Average HR significantly and positively correlated with mean speed ratio (P < 0.001), but not with the average cabin temperatures (P = 0.533, range 25.6-41.8 °C) by the multiple linear regression analysis. Both average HR and mean speed ratio were significantly lower under wet, than dry conditions (151.9 ± 16.5 vs. 168.3 ± 12.5 beats min-1, 86.9 ± 4.4 vs. 93.4 ± 1.5 %).


CONCLUSIONS
The cardiovascular system of drivers is considerably stressed at extremely high HR. This high average HR positively correlated with mean speed ratio, suggesting that faster driving speed would induce greater cardiovascular stress to professional drivers during actual races. However, contrary to our hypothesis, cabin temperature was not significantly correlated with average HR. It is speculated that direct body cooling systems used in this professional race category work well against increases in HR by thermal stress under the temperature range found herein.
Division of Hygiene, Department of Social Medicine, Nihon University School of Medicine, 30-1 Ohyaguchi-kamicho, Itabashi-ku, Tokyo, 173-8610, Japan.
Ryo
R
Yanagida
Hokuranosato Clinic, Niigata, 942-0314, Japan.
Kiichi
K
Takahashi
Miura Clinic, Kanagawa, 232-0006, Japan.
Masaru
M
Miura
GT Association Co. Ltd, Tokyo, 141-0031, Japan.
Masahiro
M
Nomura
Division of Hygiene, Department of Social Medicine, Nihon University School of Medicine, 30-1 Ohyaguchi-kamicho, Itabashi-ku, Tokyo, 173-8610, Japan.
Yojiro
Y
Ogawa
Division of Hygiene, Department of Social Medicine, Nihon University School of Medicine, 30-1 Ohyaguchi-kamicho, Itabashi-ku, Tokyo, 173-8610, Japan.
Ken
K
Aoki
Division of Hygiene, Department of Social Medicine, Nihon University School of Medicine, 30-1 Ohyaguchi-kamicho, Itabashi-ku, Tokyo, 173-8610, Japan. iwasaki.kenichi@nihon-u.ac.jp.
Ken-Ichi
KI
Iwasaki
D000328:Adult; D001334:Automobile Driving; D006339:Heart Rate; D006358:Hot Temperature; D006801:Humans; D008297:Male; D018986:Motor Vehicles; D013177:Sports
Cardiovascular system; Gravitational loading; Motorsport; Psycho-physiological influence; Thermal stress