Out of all the medical and lifestyle interventions we can use to improve our quality of life and prevent chronic diseases, regular physical activity is by far the most potent tool. Regular exercise improves aerobic fitness, increases muscle mass and improves metabolic health, all key factors in the prevention of diseases such as heart disease, obesity, dementia and cancer.
The ideal exercise program would include a combination of strength training to increase muscle mass as well as cardiovascular training. The importance of the strength training, in particular with regard to minimising frailty, was discussed in a previous blog. Cardiovascular training includes a range of types of training which differ in duration and intensity. Zone 2 training is a workout which is done at moderate-intensity at a steady pace which may be sustained for long periods of time.
When we exercise our heart rate increases in order to pump oxygen transported in our blood from our lungs to our muscles more quickly. The more intense the exercise is, the faster our heart beats and therefore the higher the heart rate. Exercise may therefore be classified in terms of what heart rate range you are in - this is zone-based training. At rest you are in Zone 0 whereas when you exercise at maximum intensity you enter into Zone 5.
Zone 2 may be described as training in which you are exercising at moderate intensity. Your breathing is relatively comfortable, requiring occasional pauses, and the intensity and pace you are at can be maintained for hours. On the other hand, Zone 5 exercise involves a much higher level of intensity and shorter duration.
Zone 2 exercise is one of the most effective tools to improve metabolic health and achieve longevity. One should do aim to do 80% of their cardiovascular training in Zone 2, and the remaining 20% in Zone 5 in order to increase your VO2 max (aerobic fitness level) which declines naturally with age.
To be in good metabolic health means that our body can respond to food entering our body without unhealthy spikes in blood sugar, insulin, blood fat, and inflammation. This type of low intensity, sustained exercise improves insulin sensitivity and glucose uptake by muscles - promoting metabolic health. Zone 2 exercise enhances our body’s ability to produce energy. Mitochondria, which are the main energy production sites in our cells, increase in number and efficiency when the energy requirements of our cells increase. Healthier mitochondria mean a healthier and better performing body. By regularly doing zone 2 training over time, we train our mitochondrial system to serve our body better by increasing the number and efficiency of our mitochondria as well as clearing out old or malfunctioning mitochondria. Additionally, long term zone 2 exercise strengthens your heart muscle. This increases your capacity for a range of activities enabling you to carry out everyday tasks with greater functionality as you age.
Our bodies can use either fat or glucose as energy sources. Its ability to shift between using these two is known as metabolic flexibility. During low or moderate intensity exercise our bodies uses fat as its primary source of energy, which is why zone 2 training is also known as the fat burning zone.
As intensity increases there is a gradual shift to utilisation of glucose for energy. Training in Zone 2 promotes this metabolic flexibility which in turn lowers the incidence of insulin resistance and the related risk of various associated chronic diseases.
Zone 2 training may be performed by walking, jogging, running, cycling, swimming and elliptical training. The key is to train at a low enough intensity for it to be sustainable over prolonged periods of time. In order to do so we must first and foremost be able to measure intensity. There are many wearables which can display which heart rate zone you are exercising in. Alternatively, another way is to train at an intensity at which you are still able to hold a conversation with the occasional pause.
Simply put, being metabolically healthy reduces your risk of many chronic diseases, increases your health span and lifespan and one of the best tools to do this is exercising within Zone 2. Doing this type of training several times a week for just 30 minutes at a time will reap benefits in the long term. Once you achieve this comfortably you may build up the duration of this zone 2 training. As it is such low intensity this can be done frequently and for long durations without risking injury or downtime required for recovery. Find out more about the Longevity Annual health check and download the longevity doctor guide to healthy living.