Helgerud, J., H°ydal, K. L., Wang, E., Karlsen, T., Berg, P. R., Bjerkaas, M., Simonsen, T., Helgesen, C. S., Hjorth, N. L., Bach, R., & Hoff, J. (2006). Differential response to aerobic endurance training at different intensities. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 2581.

This study compared the effects of aerobic endurance training at different intensities with different methods matched for total work and frequency. Male students (N = 40) were randomly assigned to one of four groups performing similar workload: 1) long slow distance (70% maximal heart rate; HRmax), 2) lactate threshold (85% HRmax), 3) 15 x 15 seconds interval running (15 seconds running at 90-95% HRmax followed by 15 seconds active resting), and 4) 4 x 4 minutes interval running (4 minutes running at 90- 95% HRmax followed by 3 minutes active resting at 70% HRmax). All groups trained three days per week for eight weeks. The training protocols were matched for total oxygen expenditure.

High intensity interval training of 15 x 15 seconds and 4 x 4 minutes, respectively, resulted in significantly larger increases in maximal oxygen uptake compared to long slow distance and lactate threshold training intensities. The percentage increases for the interval training groups were 6.1% and 8.1%, respectively. The stroke volume of the heart changed significantly for the two interval groups. Changes in VO2max corresponded with changes in stroke volume of the heart, indicating a close link between the two. No significant changes or differences among groups were observed in lactate threshold when expressed as a percentage of VO2max. Running economy improved in all training groups with no differences between groups.

Implication. High aerobic intensity interval endurance training is significantly more effective than the same total work of low intensity training in improving VO2max.

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