Myth: High Intensity Interval Training (HIIT) is good for you.
Busted! Well, sort of. While HIIT, which has been very popular for several years now, has some great benefits, there are some situations where it’s not a good idea.
HIIT can take many forms, but it is essentially a workout where the intensity level varies and includes bouts of very high intensity work followed by periods of recovery. Tabata is one form of HIIT. Running sprints followed by walking is another form. The benefits include the ability to burn more calories in less time, increased endurance, and weight loss (among others). Studies have shown that HIIT causes the metabolism elevation that takes place after exercise to last longer than with more moderate, steady workouts.
The problem with high intensity exercise is that it is a form of stress. There is good stress and bad stress, and usually the body handles good stress, such as stress from exercise, during recovery. Our best recovery time is during sleep. So, what happens to people who are not sleeping well? They can’t recover from high intensity exercise.
Post- and peri-menopausal women have a high incidence of sleep disruption. Hot flashes and night sweats interrupt sleep, but many women have difficulty falling asleep in the first place. Decreased estrogen levels affects melatonin, the hormone that helps us fall asleep. Melatonin is also disrupted by stress (which can be from intense exercise or stresses of daily life). Also, when women don’t sleep well (see Do Women Need More Sleep Than Men? and Sleep Hygiene 101) they aren’t producing enough growth hormone and DHEA, which are restorative hormones.
A study called the Dose-Response to Exercise in Post-menopausal Women (DREW) found that the national guidelines of about 30 minutes a day, or 150 minutes a week of moderate-intensity exercise is still supported. However, they also found that a lower volume of about 72 minutes per week was associated with significant health and fitness improvement in women in the 55-59 age group. Too much exercise is harmful to women as they age because of the lack of sufficient recovery, and if they can still benefit from lower volumes, they should reduce both volume and intensity.
So, if a woman is not sleeping well, she should avoid HIIT until her sleep problems are addressed*. If she is getting good quality sleep regularly, she can most likely tolerate HIIT.
*It’s always a good idea to check with your healthcare provider to discuss sleep problems, hormone levels, and exercise.