In Japan, there is a saying, “Even a cold stone will warm up if you sit on it for 3 years,” which essentially means that if you work hard and patiently, you will see results over time.

Yamaji et al. revealed that a 3-year exercise regimen improved endothelial function in patients with hypertension [1]. This study is the first to show changes in flow-mediated vasodilation (FMD) in regular exercise group and control group using real-world data on endothelial function assessed using FMD.

Since the coronavirus disease (COVID-19) pandemic has been reported to interrupt exercise habits and decrease activity, this study is significant because it shows that exercise should be continued [2]. In study 2, a follow-up protocol was designed to include patients who stopped exercising, to determine the negative effects of exercise discontinuation [1]. Moreover, this study was prescient because it was planned and conducted before the COVID-19 pandemic.

Although the sitting time duration was not investigated in this study, it has been reported that the risk of mortality is higher with longer sitting times per day [3]. The disadvantages of a long sitting time and the benefits of exercise are key messages [4]. In particular, Japanese adults spend a lot of time sitting, with a total reported sitting time of 5.3 ± 3.7 hours on weekdays. The characteristics of high-sedentary people (those who spend more than 8 hours a day in total sitting time), included being overweight (BMI of 25 kg/m2 or more), being unmarried, being unemployed, and having a high educational background [5].

Although managing blood pressure by prescribing antihypertensive medications to hypertensive patients is important, it is not a fundamental treatment. It is necessary to determine the cause of hypertension and implement behavioral changes to modify lifestyle habits. Exercise has a positive effect on the entire body, including on cardiopulmonary function and peripheral skeletal muscles, and is effective as a therapy for hypertension, type 2 diabetes, cardiovascular disease, cancer, and even psychological factors such as depression and cognitive dysfunction, as the phrase “Exercise is Medicine” suggests [6]. Endothelial function declines with age, and a man is as old as his arteries. The study by Yamaji et al. [1] demonstrates that endothelial function improves with continued exercise habits, and is a true demonstration of “Exercise is Medicine” (Fig. 1). Cardiac rehabilitation requires exercise therapy and comprehensive disease management by a multidisciplinary team, which includes nutritional guidance, smoking cessation, medication guidance, and counseling [7]. Salt intake is particularly high in Japan, and the most important factor non-pharmacological treatment for hypertension is salt reduction [8].

Fig. 1
figure 1

Exercise is Medicine. A man is as old as his arteries, and it is known that endothelial function declines with age. Three years on the stone and continued exercise improved endothelial function, a true demonstration of “Exercise is Medicine”

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In the study by Yamaji et al. [1], arterial stiffness assessed using brachial-ankle pulse wave velocity (baPWV) did not change in the control and regular exercise groups after a 3-year follow-up period. A meta-analysis of 24 randomized control trials on older adult participants found that aerobic and combined training can promote major improvements in endothelial function and arterial stiffness in older adults as measured by FMD and PWV [9]. As noted in the discussion of the study by Yamaji et al. [1], there is still controversy regarding whether aerobic exercise improves arterial stiffness. This is because exercise prescriptions vary across studies, and it is premature to draw conclusions based solely on current evidence. Exercise prescription is a recommended physical activity program designed in a systematic and individualized manner in terms of Frequency (how often exercise is performed each week), Intensity (how hard the exercise is), Time (what is the duration of the exercise), Type (what is the mode of the exercise), Volume (what is the total amount of exercise), and Progression (how the program advances), which is known as the FITT-VP principle [7]. Future studies need to consider the FITT-VP to demonstrate the effects of exercise, rather than focus on whether one exercise is required.

Vascular endothelial function declines after 3 years of inactivity [1]. Another important point is that sustaining exercise for 3 years through individual efforts alone is challenging. In the study by Yamaji et al., 28.7% of participants with exercise habits stopped exercising during the 3-year follow-up period [1], which is a lower percentage than that reported in previous studies. The reason for this is the bias in participation in such studies, which makes it difficult to continue. Due to the existence of convenience in our society, we have become a society where people can live without exercise. Based on the results of the study by Yamaji et al. [1], Japan’s super-aging society requires an environment in which society as a whole can continue to exercise and a system for developing a sustainable exercise habit that does not rely solely on effort [10].