The influence of ambient temperature on power at anaerobic threshold determined based on blood lactate concentration and myoelectric signals.
OBJECTIVE
To compare the mechanical power and physiological parameters in males at the lactate (LAAT) and integrated electromyographic (IEMGAT) anaerobic thresholds during exercise testing at 23 degrees C, 31 degrees C and 37 degrees C.


METHODS
Fifteen men aged 21.9+/-1.80 years performed an incremental exercise test on a cycle ergometer at pedal frequency of 60 rpm. The test began at the power output of 120 W which was increased by 30 W every 3 min. Heart rate, oxygen uptake, carbon dioxide in expired air and minute ventilation were monitored. Venous blood samples were collected at 30 s before termination of each 3-min stage of test to determine the lactate anaerobic threshold. IEMGAT for vastus lateralis (VL) and rectus femoris (RF) muscles were regarded as the inflection point at which a non-linear increase in IEMGAT occurred.


RESULTS
IEMGAT for VL and RF were similar for all the three temperatures. IEMGAT (VL and RF) correlated closely with LAAT at ambient temperatures of 23 degrees C (r = 0.91), 31 degrees C (r = 0.96) and 37 degrees C (r = 0.97). Repeated measures analysis of variance (ANOVA) revealed that the mechanical power at LAAT and IEMGAT was higher at 23 degrees C (202+/-26.5 W vs. 205+/-22.9 W) than at 31 degrees C (186+/-20.2 W vs. 186.2+/-20.2 W) and 37 degrees C (175.5+/-25.2 W vs. 175.3+/-20.0 W) for LAAT and IEMGAT respectively (p < 0.01).


CONCLUSIONS
Higher ambient temperature induced a decrease in the mechanical power at which the anaerobic threshold occurred. The high correlation between LAAT and IEMGAT (r = 0.91-0.97) indicated that IEMGAT can be used as a practical and reliable, non-invasive method for assessment of the anaerobic threshold.
Tyka
Aleksander
A
Institute of Human Physiology, University of Physical Education, Cracow, Poland. wftyka@cyf-kr.edu.pl
Pałka
Tomasz
T
Tyka
Anna
A
Cisoń
Tomasz
T
Szyguła
Zbigniew
Z
D001944:Breath Tests; D002245:Carbon Dioxide / Q000032:analysis; D004576:Electromyography; D005080:Exercise Test / Q000379:methods*; D045853:Exhalation; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D010101:Oxygen Consumption; D013696:Temperature; D055815:Young Adult
D002245:Carbon Dioxide; D019344:Lactic Acid