By: Robbie Durand
What would you rather do to get ripped? Spend an hour on the treadmill running at a slow speed or 20 minutes doing interval training. Interval training has a ton of benefits when compared with steady state cardio activity. It takes less time to perform interval training, and it also creates more of a metabolic demand to perform and raises metabolic rate. Short-term high-intensity interval training (HIIT) induces physiological adaptations that are similar to continuous moderate-intensity endurance training despite a reduced total exercise volume and time commitment. However, it has been suggested that HIIT causes a larger excess postexercise oxygen consumption (metabolism after exercise) than endurance exercise because of the intense nature of the protocol. Sprint interval training sessions require participants to perform repeated short duration (often approximately 30–60 seconds) bouts at very high or maximal power output, each separated by a recovery period of very low-intensity exercise. There are also reports that very high intensity, short duration training can lead to loss of total body fat mass
Researchers wanted to examine the impact of high intensity sprint interval training on fat loss and cardiovascular improvements in subject’s. Body fat and lean mass were measured by and fasting blood lipid, glucose and insulin profiles were assessed before and after training. Sprint Interval Training consisted of :
-4 bouts of ×20 seconds sprints on a cycle ergometer at approximately 175% VO2 max, three times per week for 12 weeks.
Each of these intervals was separated by 2 min of very low-intensity cycling (a workload of approximately 20% of that attained at VO2max). Thus, each training session lasted less than 10 min, and only 80 s was completed at an intensity that would be expected to improve physical fitness. At the end of the study, after just 80 seconds of very intense sprint exercise per session, equal to 48 min exercise over 12 weeks, resulted in statistically significant reductions to body fat mass. Despite the very small amount of calories burned during the short, intense exercise, other contributing factors might have impacted fat loss such as an increase in post-exercise energy expenditure or overall shift towards greater fatty acid oxidation during habitual activities throughout the day, as occurs after endurance training.
Get Shredded in Less Time
This is not the only study to find interval training can enhance fat loss. In a previous study, participants performed hour-long workouts four times a week. While everyone did 40 minutes of strength training, they were divided into two groups for cardio. One group ran for 20 minutes on treadmills, and the other group performed body-weight intervals for 20 minutes. At the end of eight weeks, the interval participants lost two inches of belly fat compared to the runners who lost less than one inch.
A new study published this year suggest that very short rest periods between bouts are the key to making the most out of interval training. Researchers had cyclists do interval training for about 40 minutes twice a week for ten weeks. They combined the interval training with their regular training. Half of the cyclists did more or less classical interval training: cycling for 4.5 minutes as fast as they could and then 2.5 minutes cycling gently to recover. They repeated this cycle until the 40 minutes were up. The other half of the cyclists did a more explosive kind of interval training, with shorter cycles: they cycled as fast as they could for 30 seconds and then cycled gently for 15 seconds. They repeated this cycle for 9 minutes and then rested for 3 minutes. Then they started a second series, completing a total of 3 series. At the end of the study, there were no differences between groups in the total volume of both HIT and low-intensity training. The short rest period group (30 seconds and then cycled gently for 15 seconds) achieved a larger relative improvement in VO2max than the longer rest period group (4.5 minutes as fast as they could and then 2.5 minutes cycling gently to recover). The cyclists who did the short rest period interval training also developed more power and were, therefore, faster. The longer rest periods training, on the other hand, had little effect in this department.These results suggest that the present shorter rest interval training protocol induces superior training adaptations on both the high-power region and lower power region of cyclists’ power profile compared with a longer rest period protocol. So if you want the best gains in cardiovascular and anaerobic power from interval training, keep your rest periods short.
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