Purpose: The present study compared the effects of aerobic endurance training at different intensities and with different methods matched for total work and frequency. Responses in maximal oxygen uptake (V˙O2max), stroke volume of the heart (SV), blood volume, lactate threshold (LT), and running economy (CR) were examined.
Methods: Forty healthy, nonsmoking, moderately trained male subjects were randomly assigned to one of four groups:1) long slow distance (70% maximal heart rate; HRmax); 2)lactate threshold (85% HRmax); 3) 15/15 interval running (15 s of running at 90-95% HRmax followed by 15 s of active resting at 70% HRmax); and 4) 4 × 4 min of interval running (4 min of running at 90-95% HRmax followed by 3 min of active resting at 70%HRmax). All four training protocols resulted in similar total oxygen consumption and were performed 3 d·wk−1 for 8 wk.
Results: High-intensity aerobic interval training resulted in significantly increased V˙O2max compared with long slow distance and lactate-threshold training intensities (P < 0.01). The percentage increases for the 15/15 and 4 × 4 min groups were 5.5 and 7.2%, respectively, reflecting increases in V˙O2max from 60.5 to 64.4 mL·kg−1·min−1 and 55.5 to 60.4 mL·kg−1·min−1. SV increased significantly by approximately 10% after interval training (P < 0.05).
Conclusions: High-aerobic intensity endurance interval training is significantly more effective than performing the same total work at either lactate threshold or at 70% HRmax, in improving V˙O2max. The changes in V˙O2max correspond with changes in SV, indicating a close link between the two.
1Department of Circulation and Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, NORWAY; 2Hokksund Medical Rehabilitation Centre, Hokksund, NORWAY; 3Department of Physical Medicine and Rehabilitation, St. Olav's University Hospital, Trondheim, NORWAY
Address for correspondence: Jan Helgerud, Ph.D., Medicine, Faculty of Medicine, Norwegian University of Science and Technology, NO-7489, Trondheim, Norway 7489; E-mail: Jan.Helgerud@ntnu.no.
Submitted for publication February 2006.
Accepted for publication November 2006.