Physical activity is more than beneficial: people who exercise regularly stay healthy and minimise the risk of chronic diseases. As many people do not have enough time for endurance sports in everyday life, efficient sports programmes, such as high-intensity interval training – HIIT for short – are becoming increasingly important. ‘HIIT is a special form of endurance training in which short, intensive periods of stress are alternated with recovery periods,’ explains Dr. Dejan Reljic, Head of Sport Science and Performance Physiology at the Hector Centre for Nutrition, Exercise and Sports at Universitätsklinikum Erlangen. ‘Studies in highly obese patients show that cardiovascular performance, blood pressure or body fat levels improve thanks to HIIT,’ reports Dr. Reljic. Dr. Reljic has developed an extremely efficient HIIT programme with a duration of 14 minutes twice per week, which is successfully used in various patient groups at the Hector Centre. In a recent comparative study, Dr. Reljic has demonstrated for the first time that not only HIIT, but also moderate-intensive interval training (MIIT) significantly improves the health of obese patients: ‘This means that interval training has a health benefit even if it is only carried out with moderate intensity,’ Dr Reljic explains.
‘Interval training courses are attractive because they can achieve health-protective effects in a manageable amount of time,’ says Dr. Reljic. ‘After just a few weeks, we were able to observe clinically significant improvements in the cardiometabolic risk profile in obese patients thanks to the HIIT training in combination with an adapted diet,’ reports Prof. Dr. Yurdagül Zopf, head of the Hector Centre and spokesperson of the Obesity Centre at Universitätsklinikum Erlangen. ‘Some of these benefits are even comparable to those of drug therapy.’
MIIT – Comparative study with moderate-intensive interval training
‘The short, high-intensity stress phases in HIIT at more than 80 percent of the maximum heart rate are in principle easy to cope with even for untrained patients,’ explains Dr. Reljic. ‘Overall, there are only a few contraindications in which such training is not possible.’ Nevertheless, in a recent comparative study, the sports scientist investigated whether the extremely efficient HIIT program can still produce health benefits even at a lower intensity. For this purpose, a total of 117 obese patients with metabolic syndrome were assigned either to HIIT (intervals with an intensity of more than 80 percent of the maximum heart rate) or to MIIT (intervals with an intensity of less than 80 percent of the maximum heart rate) or to a control group without any training. All participants also received dietary advice to support weight loss. After the twelve-week training phase, participants in the HIIT group improved their cardiovascular performance and cardiometabolic risk profile the most, as expected. However, the MIIT group also showed a significant improvement in performance and cardiometabolic risk profile. Participants in the control group without any interval training only managed to reduce their weight.
MIIT in preparation for HIIT
‘If there are no contraindications, we recommend the more intensive HIIT variant to our patients, as it is more effective. In any case, in addition to a dietary change with a reduction in calorie intake, increased physical activity should also be sought in order to optimally improve the cardiometabolic risk profile,’ emphasises Dr. Reljic. ‘For people who are not yet able to implement HIIT or motivate themselves for more intensive training, MIIT can be a good alternative or helpful preparation for further training,’ summarises Dr. Reljic.