Validity of the heart rate deflection point as a predictor of lactate threshold during running

• Published in: Journal of applied physiology (1985) Vol. 87; no. 1; pp. 452 - 459
• Main Authors: Vachon, John A, Bassett, David R., Jr, Clarke, Stephen
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01-07-1999; American Physiological Society
• Subjects: Adult; Anatomy & physiology; Biological and medical sciences; Exercise; Exercise Test; Fundamental and applied biological sciences. Psychology; Heart; Heart Rate - physiology; Humans; Lactic Acid - blood; Male; Models, Biological; Physical Endurance - physiology; Reproducibility of Results; Running - physiology; Time Factors; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Heart; Treadmill exercise; Physical exercise; Human; Deflection; Physical performance; Prediction; Running locomotion; Heart rate; Lactates; Sport; Endurance; Circulatory system; Threshold
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1999.87.1.452

Exercise Science Unit, The University of Tennessee, Knoxville,
Tennessee 37996-2700
During an
incremental run test, some researchers consistently observe a heart
rate (HR) deflection at higher speeds, but others do not. The present
study was designed to investigate whether differences in test protocols
could explain the discrepancy. Additionally, we sought to determine
whether the HR deflection point accurately predicts lactate threshold
(LT). Eight trained runners performed four tests each:
1 ) a treadmill test for maximal
O 2 uptake,
2 ) a Conconi test on a 400-m track
with speeds increasing ~0.5 km/h every 200 m,
3 ) a continuous treadmill run with
speeds increasing 0.5 km/h every minute, and
4 ) a continuous LT treadmill test in which 3-min stages were used. All subjects demonstrated an HR deflection on the track, but only one-half of the subjects showed an HR
deflection on the treadmill. On the track the shortening of stages with
increasing speeds contributed to a loss of linearity in the speed-HR
relationship. Additionally, the HR deflection point overestimated the
LT when a continuous treadmill LT protocol was used. In conclusion, the
HR deflection point was not an accurate predictor of LT in the present study.
Conconi test; exercise; endurance; performance; blood lactate