The Benefits of HIT/HIIT Training
Exercise and physical activity are extremely important for our overall health and wellbeing. With evidence showing physical activity improves; quality of life, sleep, cognition, physical function, insulin sensitivity, while reducing the risks of; clinical depression, dementia, a raft of cancers and chronic preventable diseases, as well as anxiety, blood pressure, weight gain and falls. The current recommendations for physical activity are for 150 minutess per week of moderate to vigorous exercise, this means exercising to an intensity where it is still possible to maintain a conversation but with difficulty. High intensity (with/without intervals) training is a great way of efficiently reaching that 150 minutes per week mark with a host of added benefits.
High Intensity Training (HIT) / High Intensity Interval Training (HIIT)
HIIT refers to exercise that occurs in frequent short burst or “sprints” of high intensity exercise, with recovery periods. The sprints can last from 30 seconds to 4 minutes, with recovery periods lasting anywhere from 1 to 4 minutes and repeated sprints of 2 to 6 cycles per session. For true HIIT to be achieved, heart rate (HR) needs to reach 85-90%+ of max HR during the sprint effort. This is the key difference with moderate continuous training (MCT) where HR will only reach 60-70% of max HR.
In healthy individuals HIT/HIIT programs have been clearly shown enhanced exercise capacity, muscle strength and muscle oxidation compared to MCT. It may also improve cardiovascular fitness and function, as well as anxiety and depression severity. It has been associated with improvements in these same variable in individuals with cardiovascular disease, spinal arthritis and multiple sclerosis, in addition to reducing the disability associated with these diseases. In obese and overweight individuals it is as effective in the short-term as MCT at modest reductions in body fat and waist circumference, which suggests it may be a more time efficient way to exercise. Additionally there is also evidence showing it is well tolerated and has greater improvements in disability and exercise capacity in individuals with nonspecific low back pain when compared to MCT.
What Type of HIT/HIIT Program?
One of the appealing features of HIIT programs are how time efficient they are, especially when compared to MCT. In addition to this, HIIT programs appear to result in similar or greater endurance performances and VO2max (a measure of fitness) when compared to MCT.
Cardiovascular protocols utilizing short intervals (30 seconds or less), for 5 minutes or less, performed 4 or fewer times per week will assist in developing VO2max in the general population. However, the greatest improvements come from longer sprint intervals (2 minutes or longer), higher volume (15 minutes or longer) over a longer duration (4-12 weeks). Resistance training HIT protocols are typically defined as more than 70-80% of a 1 repetition maximum, performed at a maximum of 1 set of 12 repetitions.
Finally, for anyone considering a HIIT program it is important to note that even though HIIT appears to be safe for most individuals, consulting a health/medical practitioner to determine if a HIIT program is safe for you is extremely important before you start any HIIT program.