We have all seen movies where right before the hero starts fighting, he cracks his knuckles and makes it look like the coolest thing in the world! But then our parents told us that you should not crack your knuckles because that weakens your grip and hand strength. But is that true? While many people do say that they experience a small loss in strength immediately after they crack their knuckles, but are their long-term effects to it? And what is the sound actually coming from?

The reason why people crack their fingers is because the evident and sharp crack noise causes a sense of relief. Many people also do it when they have done an activity that required them to work with their hands a lot like typing or sewing, giving themselves a sense of satisfaction, similar to stretching after doing hard work. That "crack" sound can make some people cringe, while others find it strangely satisfying. Cracking your knuckles is a pretty common habit, but there are a lot of misunderstandings about it. Some people do it without even thinking, others can't stand the noise, and some can't crack their knuckles at all. You might have been told as a kid that it causes arthritis or makes your fingers swell up. But those are just old wives' tales. There's a real science behind this habit, and it's more interesting than you may think.

Why Do Knuckles Make That Popping Sound?

The "crack" isn't actually bones breaking or anything bad happening to your joints. It's a normal thing called "crepitus." This just means harmless popping, snapping, or grinding sounds that come from your joints. The main reason you hear this sound is because of gas bubbles in the fluid that cushions your joints. This fluid is called synovial fluid. When you move or stretch, these tiny bubbles form and then pop, making the sound. It's totally normal and doesn't hurt you. Sometimes, especially in bigger joints like your knees, shoulders, or ankles, the sound can also happen when the stretchy tissues that connect your bones (ligaments and tendons) move slightly and then snap back into place.

After you crack your knuckles, you can't usually do it again right away. You have to wait a bit. That's because the gas bubbles in your joint fluid have already popped, and it takes a little while for them to build up again. While cracking your knuckles doesn't give you arthritis, doing it too much might cause some problems. Doctors say that cracking them too often could make your joints a little wobbly and might even make your grip weaker. Also, if the stretchy tissues in your joints keep snapping over your bones, they can get irritated and sore.

When Joint Popping Might Mean Something More

Sometimes, a pop in your joint is just like cracking your knuckles, nothing to worry about. But other times, it can be a sign of something else. As we get older, the cushiony stuff in our joints, called cartilage, can start to wear down. This cartilage helps your bones move smoothly. When it gets thin or uneven, the bones can rub together, and that can make a grinding or popping sound. This is different from the pop you get from gas bubbles. If this grinding sound happens along with pain, it could be a sign of osteoarthritis. This is a type of joint problem that's more common in older people, but younger people can get it too, especially after a joint injury. If your joints hurt, especially in the morning or after you've been sitting still for a while, feel wobbly, or are hard to move, it's a good idea to see a doctor.

Beyond lung cancers, air pollution fine particulate matter (PM2.5) is increasing mortality for breast as well as liver cancers, according to a global study led by the Union for International Cancer Control (UICC), including researchers from the Indian Council of Medical Research (ICMR).

The important study showed that long-term exposure to PM2.5 increases the overall risk of developing cancer and the chances of dying from it compared with those living in cleaner environments.

For every 10 micrograms per cubic meter (µg/m³) increase in PM2.5 exposure, the overall risk of cancers increases by more than 11 per cent. At the same time, the risk of death also increases by more than 12 per cent for every 10 µg/m³ increase in PM2.5 exposure.

The researchers argued that while other common risk factors like tobacco and alcohol are being targeted with notable progress, air pollution is silently eroding the gains being made.

“We have made huge strides in reducing deaths from cancer, but polluted air is silently undermining that progress. It is a risk people cannot opt out of, and one that disproportionately affects women, children, and people living in poverty,” Cary Adams, CEO, UICC.

“The cancer community continues to make progress in addressing other major risk factors, including tobacco use, alcohol consumption, and viral, bacterial, or parasitic infections such as HPV and HBV that cause cervical and liver cancers. It is increasingly clear that air pollution must also be recognized as a major and preventable factor that increases the risk of developing cancer and of dying from the disease,” added Dr Elisabete Weiderpass, Director, IARC.

Risks of PM2.5: Beyond Lung Cancer

The study, based on data from 42 meta-analyses and systematic reviews published between 2019 and 2024, showed significantly strong associations for liver, colorectal, and breast cancers.

As per recent data from the International Agency for Research on Cancer (IARC), PM₂.₅ exposure contributes to 434,000 lung cancers per year, accounting for more than a quarter of preventable lung cancers in women and nearly one in six in men.

In addition to lung cancer risk, the study noted that the rising levels of PM2.5 are associated with

• a 32 per cent higher incidence of liver cancer
• an 18 per cent increase in the odds of developing colorectal cancer.

• a 12 per cent higher overall risk of dying from cancer,
• a 20 per cent higher risk of death from breast cancer,
• a 14 per cent from liver cancer,
• a 12 per cent from lung cancer.

Who Is At A Higher Risk

According to the researchers, people living in low- and middle-income countries bear the greatest overall burden. These countries frequently lack the resources to reduce pollution at source or to provide timely access to cancer prevention, diagnosis, and treatment.

The challenge is compounded by the projected rise in global cancer cases, expected to increase from 20 million in 2022 to 35 million by 2050. People at risk include:

• Women and children, particularly in settings where solid fuels are used for cooking and heating.
• Women exposed to household air pollution face a 69 per cent higher risk of lung cancer, alongside increased risks of cervical cancer.
• Outdoor workers and communities living near industrial facilities are also at heightened risk, with exposure often concentrated in economically deprived areas.

What Actions Are Required?

The researchers underscored that the evidence presented in the report is already sufficient to justify decisive action to reduce exposure to polluted air. They called upon policymakers to make required changes across energy, transport, industry, and urban planning to reduce the risk of cancer from air pollution.

The study urged the need for properly implementing effective interventions that are well-established. These include:

• Stronger emissions standards and enforcing the WHO air quality Standards
• A transition to clean energy and clean cooking
• Improved urban design by investing more in green infrastructure
• Expanded air-quality monitoring in High-Risk Areas
• Update cancer control plans.

During the summer, it is important to stay hydrated, but for kidney patients, excessive intake of fluids is just as dangerous as not drinking enough. Most people are encouraged to drink extra fluids during hot weather; however, patients with chronic kidney disease (CKD) and those on dialysis must exercise greater control over their daily hydration and fluid intake because their bodies cannot effectively excrete excess fluids, leading to potential complications.

What is overhydration?

Dr Anupam Roy, Additional Director – Nephrology and Kidney Transplant at Aakash Healthcare Multi-Specialty Hospital, Dwarka, said, “Overhydration occurs when the body retains more fluid than it is able to eliminate. For kidney patients, overhydration typically leads to fluid overload as a result of excessive fluid accumulation in the body. Early signs of fluid overload may include swelling in the feet, ankles, and/or face. If not treated, fluid may continue to build up and cause the lungs to fill with fluid, resulting in shortness of breath and difficulty lying down. If left untreated, gaseous exchange in the lungs will be impaired, and the patient will require immediate medical treatment for pulmonary oedema (a life-threatening complication).”

What happens when you are overhydrated?

The effect of excess fluid on the heart and blood pressure is considered a significant concern. Excess fluid results in additional strain on the cardiovascular system, leading to high blood pressure. This extra workload may also increase the risk of serious complications (e.g., heart failure) for individuals who already have hypertension or heart disease. Dialysis patients are at particular risk of developing complications since they rely on regularly scheduled treatments to remove excess fluid. Excessive fluid consumption between dialysis sessions may complicate and increase the discomfort associated with removing excess fluid during dialysis.

How does overhydration affect kidney disease patients?

Overhydration may also cause an imbalance in electrolytes, such as sodium. Consuming a large amount of water without adequate intake of electrolytes could dilute sodium in the bloodstream, resulting in hyponatraemia. Symptoms of hyponatremia vary from mild (nausea and headaches) to severe (confusion, seizures, and, in extreme cases, coma). This condition can potentially be life-threatening for kidney disease patients, who often have difficulty maintaining an optimal balance of electrolytes.

Many people forget that they can obtain fluids from certain foods and drinks, such as soup, yogurt, watermelon, and tea or juice. In the summertime, people tend to consume these types of foods and drinks more often, which can cause them to exceed the recommended daily fluid intake. Many also believe that drinking extra water will flush toxins out of their system; however, when the kidneys are not functioning properly, excess fluids can be difficult to remove from the body.

How much water should kidney patients drink?

Dr Roy said that proper hydration for someone with kidney disease needs to be planned carefully. The amount of fluid a person can consume depends on their stage of kidney disease, urine output, and whether they are on dialysis. Some simple strategies can help maintain proper hydration: use small cups for drinks, consume fluids throughout the day rather than all at once, avoid foods high in salt (as these increase thirst), and track daily fluid intake.

The main reason for drinking fluids is to ensure the right amount is consumed; therefore, the most important aspect of hydration is maintaining balance. Maintaining this balance can help prevent complications and allow individuals to remain as healthy as possible. When kidney patients understand their hydration needs and receive proper guidance during the summer, they can avoid causing further harm by placing additional strain on their bodies.

The U-WIN (Universal Immunization Win) platform has been transformative and has helped India tackle the concerning burden of zero-dose children, said Dr NK Arora, an immunization expert and member of the National Technical Advisory Group on Immunisation in India (NTAGI).

In an exclusive conversation with HealthandMe during World Immunization Week 2026, Dr Arora, Executive Director of The INCLEN Trust International, traced the journey of the U-WIN portal and explained how it has strengthened vaccine uptake in the country.

U-WIN is a digital platform and app to help people find vaccination centers near their residences, manage vaccination appointments at health facilities, and maintain vaccination records.

Dr Arora noted that the U-WIN portal created a digital ecosystem that played a critical role in registration, appointment scheduling, vaccine tracking, and real-time monitoring.

The Origin Of U-WIN

U-Win was launched in October 2024 and is available in 12 languages, including English.

Dr Arora, also the chair of the COVID-19 and HPV vaccine working group, shared that during the deadly COVID pandemic in 2020—around July—it became very clear that to vaccinate 140 crore people, some kind of IT platform is needed that will track individuals who had been vaccinated, especially when they needed their second dose, and later, booster doses.

“Everything started somewhere around July 2020, and by January 2021, we had the Co-WIN platform. By mid-April, things were streamlined. The platform gives us a long list of individuals who have been vaccinated. It also helps to know who has been left out of the vaccination.

“It is like a registry of human beings who are getting immunized. And we could send reminders, we could send certificates, and we can also tell the individual when to get their second and third dose,” the expert said.

He noted that as COVID became less intense toward the end of 2021, serious discussions began on using the same platform for routine immunization. This is where the concept of U-WIN came in 2022. It has now been piloted and is gradually being used.

U-WIN: Closing the Gap For Missed and Zero-Dose Children

The UWIN now has the mechanism to ensure that immunization is completed for everyone who registers. One user can register up to 10 people in one mobile number, including citizens/guardians, pregnant women, infants (0-1 years), children (1-7 years), and adolescents (7-19 years).

“The key issue is that tracking provides two or three important inputs. First, it ensures that everyone is getting vaccinated and that it is not dependent on memory. There is a proper record—whether a person or child has received vaccines and what their current status is, including whether the schedule is complete,” Dr Arora said.

“Second, one of the main reasons for missing or delaying the next dose was that mothers often did not remember. Fathers contributed very little to this process, but they also became involved because of the reminder system,” he added.

Another important role of U-WIN is tackling the so-called zero-dose children—those who have never been vaccinated.

“About 4–5 per cent of our eligible population falls into this category, meaning they have not received even the first pentavalent dose. On the face of it, 4–5 per cent may not seem like a huge problem. But when we look at the absolute numbers—out of 26 million—it translates into a very large number, which we cannot afford to miss. So tracking helps identify these children through the micro-plan system”.

U-WIN Enables Life-course Immunization

Also read: World Immunization Week: Vaccines Are Like Insurance, They’re Safe—Take Them, Says Dr NK Arora

“When a child is vaccinated, we know when boosters are due—at one and a half years, then at five years. But none of us remembers this. Even among well-informed parents, this is often forgotten. This system helps address that gap,” Dr. Arora said.

Further, when the same individual becomes eligible for vaccines like HPV—typically between 9 and 14 years—there is again a gap that needs to be addressed.

Certification is another benefit, as it creates a documented process, particularly for programs like oral polio vaccination.

Dr. Arora highlighted that in case of any future pandemic-like situation that requires repeated vaccinations, “we have a mechanism in place”.

“This IT platform has truly transformed the system. There is also a lot of discussion about using similar platforms for TB patients, pregnant women, and other flagship programs like non-communicable diseases. So, for India, digitalisation is at its best when we talk about U-WIN.”