It has been shown that a rehabilitation program that includes exercise training reduces mortality in subjects with coronary heart disease. To have a high cardiorespiratory fitness, that is a high maximum oxygen uptake (VO2max), is strongly predicting survival in these subjects – as well as in the rest of us.1 Therefore, it is smart to find out how to increase the VO2max effectively by exercise training.
In CERG, we have done several studies showing that high intensity interval training (HIT) give larger improvements in VO2max compared to moderate continuous exercise.2,3 Our training studies typically last for three or four months, with a lot of supervision and good patient compliance. But is HIT something people can do on a regular basis during the rest of their life?
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In one study comparing HIT and moderate continuous training in subjects after coronary artery bypass surgery, we found no difference between the increases in VO2max between the two groups.4 These patients were, however, only staying four weeks at a rehabilitation center. When we invited them back for a new test six months after discharge, the HIT group had improved their VO2max since leaving the center, while the moderate continuous group had not. The reason for this improvement, we believe, is that they continued to do HIT at home. But for how long are people able to do this?We don’t know, yet.
In another study, we saw that VO2max declined at six and thirty months after ending cardiac rehabilitation.5 This lead us to do a study, recently published in PLos One, were we assessed if a maintenance program following discharge form cardiac rehabilitation could improve the adherence to exercise and thereby prevent decline in VO2max. We designed a program with monthly supervised HIT sessions and testing of VO2max every third month, and thought that the patients who got this extra supervision during one year would decline less than patients not receiving the program. This was, however, not found. Both groups maintained the same level of cardiorespiratory fitness as they had 12 months earlier when ending the cardiac rehabilitation at the hospital. For us as researchers trying to show how excellent our maintenance program was, this was somewhat disappointing. But off course, for the patients this was a positive finding! The adherence to exercise in this study was good, and overall close to 80% of the patients reported to exercise more than twice weekly after 12 months.
Trine Tegdan Moholdt, Post Doc at CERG
- Myers J, Prakash M, Froelicher V, et al. Exercise capacity and mortality among men referred for exercise testing. N Engl J Med. Mar 14 2002;346:793-801.
- Wisloff U, Stoylen A, Loennechen JP, et al. Superior cardiovascular effect of aerobic interval training versus moderate continuous training in heart failure patients: a randomized study. Circulation. Jun 19 2007;115:3086-3094.
- Rognmo O, Hetland E, Helgerud J, et al. High intensity aerobic interval exercise is superior to moderate intensity exercise for increasing aerobic capacity in patients with coronary artery disease. Eur J Cardiovasc Prev Rehabil. Jun 2004;11:216-222.
- Moholdt TT, Amundsen BH, Rustad LA, et al. Aerobic interval training versus continuous moderate exercise after coronary artery bypass surgery: A randomized study of cardiovascular effects and quality of life. American heart journal. Dec 2009;158:1031-1037.
- Moholdt T, Aamot IL, Granoien I, et al. Long-term follow-up after cardiac rehabilitation A randomized study of usual care exercise training versus aerobic interval training after myocardial infarction. Int J Cardiol. Nov 3 2011;152:388-390.