A 2015 and meta-analysis of found that HIIT training and traditional endurance training both lead to significantly improved in healthy adults ages 18–45 but greater improvements in VO2 max were seen in those participating in the HIIT exercise regimen. Another analysis also found that HIIT regimens of one month or longer effectively improve cardiovascular fitness in adolescents and lead to moderate improvements in body composition. Furthermore, a separate systematic review and meta-analysis of seven small randomized controlled trials found that HIIT (defined as four intervals of four minutes at 85–95% of max heart rate with three-minute intervals at 60–70% of max heart rate) was more effective than moderate-intensity continuous training at improving blood vessel function and markers of blood vessel health.
High-intensity interval training can be described as an exercise session composed entirely of HIIT techniques, or as a component of an exercise plan. HIIT exercise sessions generally consist of a , then several repetitions of high-intensity exercise separated by medium intensity exercise for recovery, then a cool down period. The high-intensity exercise should be done at near maximum intensity. The medium exercise should be about 50% intensity. The number of repetitions and length of each depends on the exercise, but may be as little as three repetitions with just 20 seconds of intense exercise The specific exercises performed during the high-intensity portions vary.
A 2015 meta-analysis comparing HIIT to moderate intensity continuous training (MICT) in people with found that HIIT leads to greater improvements in VO2 max but that MICT leads to greater reductions in body weight and heart rate. A 2014 meta-analysis found that the , as measured by VO2 max, of individuals with lifestyle-induced chronic cardiovascular or metabolic diseases (including , obesity, , coronary artery disease, or ) who completed a HIIT exercise program was nearly double that of individuals who completed a MICT exercise program.
If any of the HIIT 100s exercises are new to you, you’ll need to spend some time figur- ing out how much weight you can do for 10 reps. The week before you start the HIIT 100s program, work these exercises into your training to get a gauge on appropriate weights. When estimating your 10RM, be sure to do the HIIT exercise first for that muscle group. For example, if you don’t know what your 10RM is on the bench press, do bench as the first exercise in your chest workout, aiming for a weight that allows you to complete exactly 10 reps, then follow with your typical chest routine.