To age healthily, more is needed than just occasional walks or light gardening. Older people must engage in exercise - and a combination of different exercise modalities and intensities is recommended for optimal health - explains molecular biologist and biochemist Prof. Dr. Rose Njemini. "This is the most effective remedy against the inflammatory symptoms that almost all elderly people experience."
Low-grade inflammation is a chronic, systemic inflammatory response that is mild but persistent. It is commonly associated with aging and is linked to various age-related diseases, such as obesity, diabetes, cardiovascular diseases, neurodegenerative disorders, and other chronic conditions. Where does this inflammation come from? Prof. Dr. Rose Njemini: “The underlying cause is often multifactorial, driven by immunosenescence, metabolic dysfunction, gut health, lifestyle factors, stress, and environmental exposures. Our immune system declines and gradually becomes less efficient with age. This decline is partly due to the accumulation of senescent cells, that stop dividing and enter a dormant state in response to damage or stress. While this prevents uncontrolled cell proliferation (a key feature of cancer), it also leads to their accumulation in the body.”
Is that a problem?
“Senescent cells send distress signals, like a call for help, telling the immune system: "Hey, I’m malfunctioning and could cause trouble—come clean me up!" When we’re young, the immune system quickly clears out the small number of senescent cells, keeping everything running smoothly. But as we age, the immune system slows down and doesn’t do the clean-up as well. The senescent cells stick around, keep sending distress signals, and this creates chronic low-grade inflammation in the body. Over time, this ongoing inflammation can contribute to health problems like heart disease, diabetes, and even Alzheimer’s disease.”
You study substances that protect cells from damage and stress: stress proteins. What are they?
“Stress proteins are a broad category of proteins that cells produce in response to various forms of stress, such as oxidative damage, infections, inflammation, genetic mutations, and other harmful factors. There are many types of stress proteins, but one particular group that our team has studied extensively is the 'heat shock proteins,' or HSPs. They were first discovered in fruit flies exposed to high temperature in a lab—hence the name. HSPs were originally categorized into families based on their molecular weights, but today, a more updated nomenclature is being used.”
‘Strength training - such as weightlifting or resistance training - is particularly effective’
What do stress proteins do?
“Inside the cell, HSP has two key roles. First, it carries out specific tasks based on its type. Second, it acts like a helper, making sure proteins stay stable, don’t break down, and fold correctly so they can do their job properly. For instance, the heat shock protein 70 (HSP70) ensures that the mitochondria function properly. Mitochondria are the powerhouses of the cell: they produce the energy needed for almost all cellular processes. In seniors, these mitochondria begin to function less effectively, which is one of the major problems of aging. HSP70 also enhances the immune response by facilitating antigen presentation to antigen-presenting cells, which in turn activate T-cells. Additionally, HSP70 can directly stimulate natural killer cells, boosting their ability to target and eliminate infected, damaged, and cancerous cells. T-cells and NK cells are both types of white blood cells, playing crucial roles in immune defence.
Remarkable: to produce those beneficial heat shock proteins and other stress proteins, you need to train.
“That’s correct. When you have a good workout, the amount of stress proteins within cells increases, bringing about a range of beneficial effects. Stress proteins block inflammatory pathways in the body and activate anti-inflammatory parameters. This helps keep inflammatory reactions under control, which is one of the many reasons why people feel better after exercising.”
Exercise is essential for healthy aging!
"The older you get, the more important it becomes. When older people engage in physical activity in the right way, they can significantly improve their overall well-being, reduce the risk of chronic diseases, and maintain mobility and independence for a longer time."
Does it matter what and how you do it?
"Walking is healthy, and an afternoon of gardening is too. It's certainly healthier than staying seated. However, in the context of disease prevention, more intensive exercises are required. Strength training—such as weightlifting or resistance training—is particularly effective. You have to challenge your muscles a little; otherwise, the benefits remain limited."
Intensity is a flexible concept.
"Indeed, it depends on the individual’s capacity. Our study examined how different exercise interventions affect elderly individuals. Participants performed intensive strength training (3 sets of 10 repetitions at 80% of 1 repetition maximum (RM)) or strength-endurance training (2 sets of 30 repetitions at 40% of 1RM), both three times per week. 1RM is the maximum weight someone can lift once for a specific exercise, such as a squat or bench press. We found that even a single session of training triggered a significant immune response. Over time, there was a shift from a pro-inflammatory to an anti-inflammatory profile, suggesting potential benefits for aging-related inflammation. Additionally, participants experienced increased muscle mass, highlighting the dual benefits of resistance exercise on both immunity and muscle health.
‘Twenty to 30 per cent of elderly people who break a hip develop complications and do not survive the first year’
Is 80 percent of your personal repetition maximum ideal?
" Intensive strength training is one of the most effective ways to combat muscle loss (known as sarcopenia), even in old age. Different types of exercise provide unique benefits. In our research, we explored how varying intensities of resistance training impact the body at a genetic level. After three months of training at both moderate and high intensities, we observed changes in genes linked to inflammation and immune function. However, each intensity level influenced different genes and pathways. Notably, those who trained at 80% of their maximum strength showed a greater number of genetic changes, suggesting a stronger immune response and an improved ability to fight infections."
What do you recommend for older people?
"Since different intensities affect the body in distinct ways, alternating between moderate and high-intensity resistance training may be the most effective strategy for enhancing immune function in older adults. For example, by working out on Monday, Wednesday, and Friday at different levels. Give your muscles time to recover in between. Overtraining without adequate recovery is absolutely not advisable, as it can trigger inflammatory mechanisms and even impair the immune function. If you follow the right approach consistently, the improvements can be remarkable!"
It’s said that older people lose muscle mass quickly?
"Starting from the age of 50 to 60 years, you lose 1 to 2 percent of muscle mass per year, and strength declines even faster (around 3% per year). Those who lose muscle mass will become frail, fall easily, and are more likely to have fractures. Hip fractures are particularly dangerous—about 20–30% of older adults who suffer one do not survive beyond a year due to complications. Strength training is essential for maintaining muscle, balance, and overall health as you age."
“Our ultimate goal is to harness the benefits of exercise—without the effort"
Is it ever too late to start?
"That’s the beauty of it! Our studies show that even people in their 70s and 80s can regain muscle strength through resistance training. In the past, it was believed that age-related muscle loss was inevitable, but we now know that it can be slowed, prevented and even reversed. No matter your age, your muscles still have the ability to adapt and regrow with the right training."
This awareness doesn’t seem to have fully reached the population yet.
"That’s unfortunate, especially considering the aging of the population that we’re seeing. Many people would feel better and get sick less often if they exercised regularly. As already mentioned, age-related conditions, such as, heart- and vascular diseases, diabetes, and neurological problems are often linked to chronic low-grade inflammation. If older people engaged in more physical activity, it would make a significant difference in their overall health and well-being."
You recently became a member of the Royal Academy of Medicine. Is this also to spread this message?
"I am truly honored: this recognition acknowledges my scientific contributions and impact in the field of biological aging. The Academy was specifically looking for someone with this expertise. As a member of the academy, I am ready to provide advice to governments and health institutions on policies relating to the biological aspects of aging. Encouraging strength training for older adults is essential, as regular exercise plays a crucial role in maintaining their health and well-being, and overall quality of life."
How old are you? And do you practice what you preach?
"Me? Very old! (laughs heartily). After researching this for so many years, I understand better than anyone how beneficial exercise is. So, I do my best. Honestly, if I didn’t know the science behind it, I probably wouldn’t work out—especially not in the winter (bursts out laughing). But I take part in the twenty kilometres of Brussels, and I jog 5 kilometres twice a week. Now that my kids are grown, I plan to walk five kilometres to and from work every day. That will add up to at least a couple of hours of walking each day..."
What about elderly individuals who literally cannot get out of bed, for whatever reason?
“Our ultimate goal is to harness the benefits of exercise—without the effort. As we deepen our understanding of the biochemical substances released during physical activity and their powerful role in reducing inflammation, we move closer to achieving this goal: developing exercise mimetics — medications that mimic the health benefits of physical activity without requiring actual movement. Imagine a bedridden grandma with weakened muscles, osteoporosis, and diabetes experiencing the physiological advantages of a ten-kilometre jog, simply through a targeted treatment. Such a breakthrough could revolutionize healthcare, offering mobility-impaired individuals a way to enhance their strength, metabolism, and overall well-being without physical exertion.”
BIO
Prof. Dr. Rose Njemini is a molecular biologist and biochemist with over 25 years of experience in academic research. She serves as the vice-chair of the Research Master in Gerontological Sciences and is a member of the Royal Academy of Medicine since 2024.