Prescribing high intensity exercise, such as HIIT, is an effective strategy for a healthy aging.
By Guy Hajj-Boutros, M.Sc.
Physical activity plays an important role in older population promoting their independence and improving their quality of life. However, current guidelines for physical activity in the elderly seem elusive. Several studies show that only 12% of people between the age of 60 to 79 meet the guidelines for physical activity. Many people over the age of 60 find the recommendations difficult to achieve due to fear of injury, lack of motivation, but the most common fact is the lack of time. Over the past 20 years, High Intensity Interval Training (HIIT) has grown in popularity. Many research protocols have been based on this type of intervention and have considered it in different populations. Several scientific evidences suggests that increasing intensity during exercise in the elderly may be associated with a greater reduction in the risk of cardiovascular disease and mortality compared to moderate intensity training (Gebel et al., 2015). Therefore, prescribing high intensity exercise, such as HIIT, is an effective strategy for a healthy aging.
HIIT training and its benefits on cardiovascular capacity
One of greatest studies with more than 10 years of follow up has shown that a single weekly session of high intensity exercise (~ 90% of maximum heart rate) for at least 30 minutes was sufficient to reduce the risk of death from cardiovascular disease. This risk was reduced by 36% in people between the age of 60-69 and by 70% in men over the age of 70 (Wisloff et al., 2006).
HIIT has been reported to be an effective and potent stimulant in improving cardiometabolic risk factors (eg; blood pressure, lipid profile, and insulin resistance) compared to continuous training in elderly at risk (Jelleyman et al., 2015). A recent study observed that HIIT (5 times 1-min intervals with 1.5-min recovery periods) performed 3 times per week for 6 weeks on a stationary bike decreased the percentage of visceral and total adipose tissue, LDL, Hb1Ac and insulin sensitivity in older men (Sogaard et al., 2017). Another study using HIIT on an elliptical device (10 sprints of 30 seconds with 1.5 min of active recovery) 3 times per week for 12 weeks has been shown to improve fasting blood sugar and blood pressure in elderly people with diabetes ( Fex et al., 2015). Interestingly, there is some evidence to suggest that even one session of HIIT can decrease arterial stiffness in healthy older people (Perissiou et al., 2018).
HIIT training and its benefits on physical and cognitive functions
The benefits of HIIT training aren’t just limited to cardiovascular fitness. HIIT also has positive effects on physical and cognitive functions in older people. For example, one study showed that lower body muscle power can be improved following 12-week HIIT on an ergocycle. The exercises sessions were done twice a week and consisted of sprinting between 45 and 75 seconds at 90% of maximum heart rate (Hurst et al., 2018). By comparing the different types of aerobic training, the study by Garcia-Pinillos et al. (2017) found that low-volume HIIT have better effects on body composition, muscle strength, mobility. and balance compared to continuous training in the elderly population. Adding the previous finding, another group of researchers compared HIIT, aerobic training and resistance training in the elderly. After 16 weeks of exercise intervention (3 times per week), the HIIT group had greater improvements in physical function and speed of information processing compared to the other two groups. (Coetsee and Terblanche, 2017).
HIIT training and cardiorespiratory capacity
It has been well established that an increase in exercise intensity appears to be associated with an increase in cardiorespiratory fitness levels (Kessler et al., 2012). High levels of cardiorespiratory capacity has been shown to be associated with a lower risk of cardiovascular disease and death from all causes in men and women over the age of 50 (Kodama et al., 2009). Some evidence even suggest that cardiorespiratory capacity seems to be the best predictor of mortality from all causes when compared to the levels of physical activity per se (Lee et al., 2011). Thus, the health improvements seen with HIIT in the elderly may be influenced by increasing levels of cardiovascular health. Overall, HIIT may be comparable and even superior in improving cardiorespiratory capacity compared to continuous training in the elderly population (Pattyn et al., 2014)
To conclude, HIIT in the elderly is possible and enjoyable, but may have important clinical / practical implications in performing this type of exercise. HIIT is also becoming an attractive and more time-efficient option for training protocols, as this form of exercise may promote physical activity in people who are short on time. Therefore, healthcare professionals may consider HIIT in planning intervention programs for older adults to maximize the benefits of physical activity. However, future studies will need to identify both the optimal dose and the minimum dose of HIIT that will be needed to maintain or improve the general health of the elderly population.
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