Lecture No.9
The Future Opened Up by Supporting Cancer Survivors in Asia

Nobuhisa MATUHASHI 

Department of Gastroenterological Surgery and Pediatric Surgery, Gifu University Graduate School of Medicine

In 2025, a significant study was announced in The New England Journal of Medicine. (Courneya, et. al, “Structured Exercise After Adjuvant Chemotherapy for Colon Cancer). This study involved patients with high-risk Stage II or Stage III colorectal cancer who have completed postoperative adjuvant therapy within 2 to 6 months after curative resection (Figure 3). 

In terms of disease-free survival (DFS) one in every 16 participants avoided a cancer recurrence or a new cancer as a result of exercise. In terms of overall survival, the improvement in OS is driven by a reduction in colon cancer-related mortality.

(3) Cancer-related fatigue: ESMO Clinical Practice Guidelines for diagnosis and treatment

Systematic reviews and meta-analyses focusing on the role of physical exercise in patients with cancer during active treatment have documented an improvement in domains such as CRF, physical and muscular strength, activity levels and aerobic fitness.

There is growing evidence that physical exercise can attenuate systemic inflammation and improve CRF, allowing patients with or without cachexia to become more capable of carrying out the activities of daily living (ADLs) and thereby to improve the functional QoL.

Despite significant evidence for exercise in the management of CRF, an exact exercise prescription for patients with CRF does not exist. Current exercise prescription guidelines focus broadly on the general well-being of patients with cancer, encouraging 150 min/week of aerobic exercise, 2 days/week of strength training and flexibility exercises on days when aerobic or resistance exercise is not carried out. Some observational and interventional studies have also suggested that patients with cancer who engage in at least 3-5 hours of moderate activity weekly may experience better outcomes and have fewer side-effects of anti-cancer therapy, including CRF.

Based on the results of RCTs and systematic reviews, physical exercise can be recommended in non-cachectic patients with cancer. Physical exercise of moderate intensity and aerobic and functional resistance exercise are recommended in patients with CRF. Physical activities like walking and home-based aerobic and resistance exercises are recommended to improve CRF and QoL.

Aerobic exercise (walking, etc.) is exercise that helps to prevent cancer recurrence, whereas resistance exercise (strength training) is exercise that builds a body capable of completing cancer treatment.

Cancer survivors consider cancer-related fatigue to be the most distressing symptom of cancer and its treatment. Even more distressing than pain, nausea, or vomiting. After treatment, cancer-related fatigue is the reason many people are slow to return to work. Exercise is therefore a part of comprehensive cancer care, and not an optional extra. 

NCCN Guidelines include the provision of cognitive behavioral therapy (CBT) and yoga. CBT is used to break the vicious cycle of negative thoughts, which results in reduced activity, physical decline and worse outcomes. Yoga involves exercise, meditation (focusing thoughts), and control of breathing and emotions. These practices are thought to help balance the body and mind. Yoga has been found to reduce fatigue, improve sleep quality, and lessen anxiety and depression in people with cancer. There is good evidence that yoga reduces fatigue, especially when practiced on a regular basis. Yoga is recommended for the treatment of cancer-related fatigue during and after cancer treatment.

In terms of patient communication guidance, when talking to patients, simply saying "You should exercise" can feel burdensome. In line with current guideline philosophy, it is more effective to frame it in the following way: Present the goal not as "exercise," but as "actions that support recovery" "On days when side effects are strong, it's okay to rest.

It is also important to remember that both aerobic and resistance exercise are needed, because if patients do only aerobic exercise, they tend to lose weight and muscle. When resistance training is added, they can build a body that can tolerate cancer treatment. 

Discussion

Dr. Kawahara noted that physical activity has come to be recognized as a valuable therapy for cancer care and survivors worldwide. She asked how Dr. Matsuhashi works to guide patients in the clinical setting to engage in more exercise so as to gain the benefits of physical activity. 

Dr. Matsuhashi noted that the important thing is not merely to order patients to exercise, but rather to support them in their recovery. Even five minutes walking can have an effect, so the patient should be treated with compassion and encouraged to do what they can in a step-by-step approach. 

A student noted the positive impact of physical activity on mental health. He asked whether mental health plays a major role compared to physical activity in terms of cancer incidence. 

Dr. Matsuhashi noted that moderate aerobic and resistance exercise can be effective for cancer-related fatigue. 

A student asked if there is any difference in exercise depending on the stage of cancer treatment. 

Dr. Matsuhashi responded that each patient is given their own exercise regimen, depending on their specific situation. 

Dr. Kawahara noted that exercise matters not only after receiving a cancer diagnosis, but also for preventive purposes. Even while preventive exercise may seem low cost, from field work in Malaysia it has been seen that perceptions are that exercise and sports are expensive for vulnerable groups. It is therefore important to focus on movement that can be done in the course of daily life. 

(3) From Physical Activity to Resistance Exercise: Practical Approaches for Everyday Life

Kazushige SASAKI noted that as Dr. Matsuhashi had mentioned at the end of his talk, exercise can be broadly classified into endurance exercise and resistance exercise. As shown here, these two types have contrasting characteristics, and their effects are therefore complementary.

The complementary effects of endurance and resistance exercise can be explained physiologically from the perspective of muscle fiber types. Broadly speaking, our muscles are composed of two main types of muscle fibers, or muscle cells: slow-twitch fibers and fast-twitch fibers. (Figure 4)

Slow-twitch fibers are relatively slow but highly fatigue-resistant, whereas fast-twitch fibers are capable of producing force quickly but fatigue more easily. These two fiber types therefore have contrasting characteristics. Everyone’s muscles contain both slow- and fast-twitch fibers, but the proportion varies from person to person. On average, however, the muscles of the legs consist of roughly equal proportions of the two fiber types. When we move our bodies, we do not recruit these two types of muscle fibers equally at all times. During light physical activities in daily life, mainly slow-twitch fibers are used. Fast-twitch fibers are recruited only during much higher-intensity movements, such as running or jumping.

Therefore, endurance exercise, which is characterized by relatively low intensity, primarily trains slow-twitch muscle fibers. In contrast, high-intensity resistance exercise recruits both slow- and fast-twitch fibers; however, because the duration of each bout is relatively short, the stimulus to the highly fatigue-resistant slow-twitch fibers is limited. Fast-twitch fibers are fatigable and not used extensively in daily life, so even brief periods of recruitment can provide a sufficient stimulus for growth. For this reason, resistance exercise can be considered a type of training that primarily targets fast-twitch fibers.

The table below shows the physical activity and exercise guidelines for health promotion issued by Japan’s Ministry of Health, Labour and Welfare in 2023 (Figure 5). 

Physical activity is a broader concept than exercise and includes activities such as walking for commuting and household activities. In the previous version of the guidelines, which was released more than a decade ago, recommended targets for intensity and duration were presented mainly from the perspective of energy expenditure through physical activity and exercise. In contrast, the new guidelines explicitly include the recommendation of “resistance exercise training on two to three days per week.” In other words, the idea that both increasing energy expenditure through movement and improving muscle mass and strength are important has finally begun to be reflected in Japan’s public health policy.

Taking a look at the data to see how much we walk on average, Japan's Ministry of Health, Labour and Welfare calculates that people in their twenties to fifties generally take between about 6,000 to 8,000 steps per day. As mentioned by Dr. Matsuhashi, a metric called METs was developed to estimate energy expenditure during various types of physical activity. METs is short for metabolic equivalence, and it expresses how many times faster energy is expended compared with resting metabolic state, which is defined as one METs.

For example, working at a usual pace is typically classified as three METs. Another important feature of METs is that energy expenditure can be easily estimated by multiplying METs by body weight in kg, and the duration of the activity in hours.

For example, if a person waning 60kg walks at a speed of four kilometers per hour, the estimated energy expenditure would be three METs times one hour times 60 kilograms, which equals 180 kilocalories. When we compare METs barriers across different activities, we can see that walking, household activities, cycling and climbing stair have METs values that are not very different from those of sports such as tennis or basketball.

Therefore, increasing opportunities and time in these types of daily physical activity reliably leads to higher energy expenditure. As is clear from the equation used to estimate energy expenditure, what matters most is increasing the total amount of active time. Whether the activity is continuous or intermittent is basically irrelevant.

Even short bouts of exercise burn fat. During exercise, it may indeed appear that very little fat is being burned, as long as energy is expanded through exercise or physical activity, the body maintains balance. When carbohydrates are abundant, they are preferentially used. And as carbohydrate availability decreases, fat becomes the primary fuel. Therefore, for the purpose of weight loss or fat loss, whether carbohydrate or fat are being used during exercise or physical activity is not a major concern.

In fact, there is a well-known study reporting that lean individuals spend less time sitting. Lean individuals spend less time sitting, whereas in contrast, obese individuals spend less time standing and moving. Everyday activities such as standing and moving throughout the day are referred to NEAT, or “non-exercise activity thermogenesis” and the authors of the study emphasize the importance of this type of physical activity.

There is a tendency to think that people with obesity are less physically active simply because moving is more hard or difficult for them. However, this study has an important follow up. Individuals with obesity were a low in a weight loss program. Although they successfully lost weight, their level of physical activity did not change at all, before and after weight loss.

Conversely, lean individuals participated in a weight gain program, but again, their physical activity levels did not change. These findings suggest that how much a person moves in daily life is largely determined by inherent individual traits rather than being a consequence of body weight itself.

This begs the question: how can we increase our level of daily physical activity? One approach whose effectiveness has been clearly demonstrated is self-monitoring one's own activity. A meta-analysis integrated findings from multiple studies. When daily step counts were fed back to participants, the number of steps increased by an average of about 2,000 steps per day compared with conditions in which no feedback is provided (Figure 6).

The Nakanojo Study similarly demonstrated that increasing step counts not only raises energy expenditure, but also leads to a wide range of health benefits. Nakanojo is a town located in Gumma Prefecture, where longitudinal data on community residents have been corrected since the late 1990s.

In this study, some participants were provided with activity monitors to measure their physical activity while others were not. The researchers then compared subsequent medical expenditures between those who received activity monitors and those who did not.

In analysis, focusing on community residents aged 40 to 60 years, it was found that medical expenditures among those who are provided with activity monitors decreased by more than 40% between 2009 and 2011. In contrast, no such reduction was observed among residents whose physical activity was not monitored.

In terms of resistance exercise, in recent years, the relationship between the weekly duration of resistance exercise and the risk of mortality and various diseases has become clearer. According to these findings,  with the exception of diabetes, resistance exercise reduces the risks of mortality and many diseases, including cardiovascular disease and cancer. Data shows that for individuals who train three times per week, each session needs to be no longer than about 20 minutes.

Even in classic studies conducted in the 1950s and 1960s, resistance exercise was shown to be highly time efficient.

In addition, our own research has shown that resistance exercise is flexible with respect to training frequency.

If we are talking about performing very short bouts of exercise at a high frequency, many of us would probably prefer to do them at home rather than going to a gym each time. Recent research has shown that for beginners without an established exercise habit, simply using ones own body weight is enough to increase muscle mass and strength. In addition, training intensity can be further increased with a bit of creativity.

Another recommendation for improving adherence is to integrate short parts of resistance exercise into your daily routine. If exercise can be incorporated naturally into everyday habits, it becomes much easier to perform consistently and to maintain over time. 

Finally, while walking by itself does not substantially increase muscle mass or strength, it does improve insulin sensitivity, which is closely related to the anabolic effect that promotes muscle growth or muscle hypertrophy. Therefore, in older adults who often exhibit reduced insulin sensitivity, synergistic effect of walking and resistance exercise can be expected.

So this key takeaways concludes my part of the lecture. Thank you very much for your attention.

Discussion

Dr. Kawahara asked Dr. Sasaki about the key points for making physical exercise stick as a habit. She asked if Dr. Sasaki had to recommend just two or three high impact tips that work for busy people, what would they be? 

Dr. Sasaki responded that resistance exercise is effective for even a short period of time, therefore it can be easy to incorporate it into a daily routine. Also, types of exercise using body weight can be easily performed at home.  Making exercise a part of daily routines is the key to making it a habit. 

A student noted that there are certain diseases that could be aggravated by exercise. Also sports injury and athletic injury cannot be overlooked. Therefore, how is it possible to balance the beneficial and harmful effect of exercise?

Dr. Sasaki responded that short periods of exercise are usually safe to incorporate for most people, even those with myopathies. However, in the case of injury it is important to not place burden on the injured area, but other areas of the body could be exercised instead. Doing what each person is capable of doing is the main thing, as even a short period of light exercise can have a measurable effect. 

A student asked if walking speed makes a difference even when the step count is the same. 

Dr. Sasaki noted that walking speed affects the weight of energy expenditure as shown in the METs table. If the walking speed is increased, the METs value increases. In the case of walking, increasing speed is effective strategy to raise your fat burning, as well as for maintaining health and preventing disease. Walking is also lower risk than running, although high-speed walking, or low-speed running are equally beneficial for health. 

A student noted that walking is often the safest option in developing countries, where running can be dangerous on the streets due to traffic accidents, etc. 

Another student asked about rest times after exercise to avoid muscle soreness. 

Dr. Sasaki responded that recent studies have shown that muscle soreness does not severely cause delay in muscle growth or development. So if you your muscle soreness is not so substantial, you can continue to exercise the following day. Exercise can be split into three or more sessions a week, with each session containing only one set of repetitions, or it could be conducted all on a single day. The choice is one of individual preference. Muscle soreness is a sign that a person trained hard, but even hard training does not necessarily cause severe muscle soreness.