The Use of Heart Rates to Monitor Exercise Intensity in Relation to Metabolic Variables

Abstract

Exercise intensity during training and competition was assessed in women runners in relation to two metabolic markers determined in the laboratory, ventilatory threshold (VT) and 4mM of blood lactic acid (OBLA). Heart rates (HRs) were then obtained during 6 days of training and during an 8 km race. These HRs were used as references for quantifying the amount of hard (>HR-OBLA), moderate (<HR-OBLA, >HR-VT) and easy (<HR-VT) intensity training. Mean maximal heart rate (HRmax) was 183 bpm, HR-OBLA was 94.8% of HRmax, and HR-VT was 82.2% of HRmax. Average weekly training time was 301.2 min, of which 45.8% was in the easy intensity range, 45.7% in the moderate intensity range, and 8.9% in the hard intensity range. Self-reports of how training time was spent differed from actual training as revealed by the monitored heart rates. Subjects reported that they completed 3 sessions per week of easy intensity training, less than 1 session of moderate intensity training, and 1.5 sessions of hard intensity training. More than 70% of the 8 km race was performed at an intensity higher than HR-OBLA (173bpm). Although 8 km race intensity closely corresponded with that at OBLA, very little training time was spent at that running intensity. HR monitoring of training intensity provided more accurate information than self-reports of training intensity.

Key words

Training intensity - lactate acid - anaerobic threshold - ventilatory threshold - OBLA - women