Applying ice to a muscle injury is a widespread first-aid treatment, but exactly what effect does this have on the muscle regeneration and does it really help? Cumulative research by a multi-institutional Japanese research collaboration reveals that ‘to ice or not to ice’ may depend on the degree of muscle injury.

In their latest research, the group consisting of Associate Professor ARAKAWA Takamitsu and Master’s student NAGATA Itsuki (from Kobe University’s Graduate School of Health Sciences), and Assistant Professor KAWASHIMA Masato (Kawasaki University of Medical Welfare) et al. have shown that applying ice to muscle damage in a small percentage of muscle fibers in rats promotes muscle regeneration. This is believed to be the first study in the world to show benefits of icing on muscle repair. In conjunction with their previous study on serious muscle injuries (‘Icing muscle injuries may delay recovery’), it is hoped that these results can be used as a basis for more accurate guidelines on whether or not to ice such injuries.

These research findings were first reported in the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology on March 6, 2023.

Main Points

• The experiments showed that applying ice after a mild muscle injury promotes muscle regeneration.
• This is believed to be the first time in the world that a study has shown a positive effect of icing on muscle regeneration.
• The researchers showed that the extent of the injury may have a greater impact on the effectiveness of icing than the method or timing employed.
• The findings of this ongoing research will lead to the spread of more accurate information on the effects of icing throughout hospitals, and in the realms of sports and physical education.

‘RICE treatment’ is a common approach for treating the acute phase of sports injuries. This acronym stands for Rest, Ice, Compression and Elevation and it is also often used in physical education in schools and even clinical settings. There are a variety of subsequent steps that can be taken to treat the injury afterwards, yet opinions vary as to whether or not icing should be applied. However, there is a lack of evidence on the benefits of icing.

The current research team has conducted many experiments to investigate the effectiveness of icing, which led them to publish their previous findings (‘Icing muscle injuries may delay recovery’ ). However, no previous animal experiments have indicated that icing promotes muscle regeneration.

In this study, the researchers focused on altering the severity of the muscle injury in the experiments. The reasoning behind this was that the majority of sports-related muscle injuries are limited; in other words less than 10% of the overall number of muscle fibers (myofibers) are damaged and necrotized. However, all animal experiments up until now had looked at more serious injuries where over 20% of the myofibers were damaged.

Thus, the team devised an animal model for mild muscle injuries, and experimented with applying ice after injury using a similar method as before.

After the animal was anaesthetized, the muscle was exposed and clamped between forceps to induce injury. In their previous experiments, the researchers attached a 500g weight to the forceps, which induced an injury that affected 20% of the total number of fibers in the muscle. In the present study, they tried attaching a 250g weight to the forceps and demonstrated that this could be used to consistently injure 4% of the fibers (Figure 1). This is similar to the degree of injury that often occurs after sports activities such as vigorous exercise or long-distance marathon running.

Icing was carried out by placing polyethylene bags of ice on surface of the skin over three 30-minute sessions per day, with each session being 1.5 hours apart. This was continued until two days after injury for a total of 9 icing sessions (i.e. immediately after injury = 3 sessions, 1 day after injury = 3 sessions, 2 days after injury = 3 sessions). The icing method was the same as in the previously reported study (‘Icing muscle injuries may delay recovery’).

Observations of muscles that were regenerating in the icing group and no-icing group 2 weeks after injury revealed significant differences in the size of regenerating fibers in cross-sections (Figure 2). In other words, this demonstrated the possibility that skeletal muscle regeneration is promoted by icing.

Macrophages are immune cells that orchestrate the reparative process of injured muscle. Pro-inflammatory macrophages accumulate in the damaged site soon after injury occurs, however they express an inducible nitric oxide synthase (iNOS), which has a disadvantageous side-effect of expanding the injury’s size. The results of this team’s experiments revealed that icing after mild muscle injury reduces the accumulation of iNOS-expressing pro-inflammatory macrophages. By causing this phenomenon, icing prevents the expansion of muscle injury size.

In other words, icing attenuates the recruitment of pro-inflammatory macrophages in the injury site. This was also reported in their previous study (‘Icing muscle injuries may delay recovery’), demonstrating that this is an effect caused by icing regardless of whether the muscle injury is serious or mild. In the previous study, icing was found to delay the regeneration of muscle after a serious injury that destroyed many fibers because the pro-inflammatory macrophages were unable to sufficiently phagocytose (*5) the injured muscle. In contrast to this, the current study shows that icing has a positive effect when the muscle injury is mild because it prevents the secondary expansion of the muscle injury caused by the pro-inflammatory macrophages. It suggests that this particular effect of icing is connected to the promotion of muscle regeneration.

Icing has been used in the treatment of muscle injuries for a long time, however the positive effects of icing had yet to be elucidated until now. This study has shown that icing can promote muscle regeneration when used to treat commonly-occurring mild muscle injuries.

However, this does not mean that icing is effective for all types or degree of muscle injury. The researchers aim to further elucidate and raise awareness of this. For example, the group’s previous study showed that icing actually inhibited regeneration in cases of serious muscle injury. In addition, the term ‘muscle injury’ also includes extremely minute injuries that have yet to be observed through the team’s animal experiments, so it is still unclear as to what effect icing has on the repair from such microtraumas.

The researchers’ next challenge is to determine the extent of muscle injury up to which icing is appropriate. By building upon their previous investigations, they aim to contribute towards guidelines that will enable people in sports and clinical rehabilitation to make accurate judgements about whether or not to ice an injury.

They’re incredibly important, yet so many people take them for granted—our teeth. A healthy smile is an important part of your overall health since your teeth are such an important and useful part of your body.

It’s crucial that you practice proper oral care, by following these habits.

Always Brush Before Bed

Dentists recommend brushing your teeth three times a day to ensure you remove harmful buildup. However, not everyone manages to make it to three, which isn’t the end of the world. Yet, if there’s one of these three brushing times that you absolutely can’t get away with skipping, it’s nighttime.

At night, your teeth have all of the food that you ate throughout the day, and also germs that cause bad breath. When you go to bed without brushing you’re allowing all of that to sit on your teeth for the duration of however long you sleep, which is usually about 8 hours. Yuck!

Visit Your Dentist

Brushing your teeth daily is already a great step towards overall tooth health. However, there are some things that a toothbrush simply can’t do. It’s important that you see a dentist regularly to get cleanings and address dental issues.

Sometimes despite our best efforts to brush, we still develop cavities. Unfortunately, this is just the way things are. A dentist can help us identify these cavities, and fill them as soon as possible so they don’t turn into something more serious like a root canal.

Floss

Despite having the best toothbrush on the market, there are crevices and cracks in your mouth that even the best toothbrush can’t touch. In addition to brushing, you should make sure that you floss.

Flossing won’t just reduce your risk of developing cavities, but it can significantly improve your breath. There are all sorts of germs and bacteria lurking in between your teeth, and flossing can get rid of that. If you notice that your breath still isn’t entirely fresh even after brushing, then pull out the floss and you’ll notice a big difference.

Avoid Sugar

There are plenty of things that are less than ideal for your health. However, most health professionals agree that one of the worst things for you is sugar and your dentist feels the same. The less sugar you eat, the healthier your teeth will be, as sugar eats away at your tooth enamel.

If you do eat sugar, make sure that you brush your teeth after. One of the worst things you can do is eat sticky candy which leaves behind residue on your teeth and is the perfect recipe for cavities.

Avoid Acidic Foods

In addition to sugary foods, acidic foods are also your teeth’s worst enemy. From coffee to citrus fruits, limit the number of acidic beverages and foods you consume, and your tooth enamel will greatly thank you for it!

If you’re a woman who tries to stay healthy, you may exercise several times per week, watch what you eat and get 7-9 hours of sleep each night. But are you listening to your lungs?

Chronic obstructive pulmonary disease (COPD), a leading cause of disability and death in the United States, takes an especially heavy toll on women. You may think problems like shortness of breath, frequent coughs or wheezing are just signs of getting older, but it’s important to pay attention to these symptoms and discuss them with your doctor.

COPD is a serious lung disease that causes breathing problems and worsens over time. It has often been considered a man’s disease. Yet more women than men have been diagnosed with COPD in the past decade, and over the past 20 years more women have died from it, according to the US Centers for Disease Control and Prevention.

Women tend to develop COPD earlier in life than men and are more likely to have severe symptoms and be hospitalized with the disease. The good news? According to the National Heart, Lung, and Blood Institute, there are steps you can take to reduce your risk for COPD.

Don’t Smoke

You probably already know cigarette smoking is harmful – but did you know that women may be more vulnerable to the effects of smoking? Women who smoke tend to get COPD at younger ages and with less cigarettes smoked than men. COPD is the leading cause of death among U.S. women smokers.

If you do smoke, it’s never too late to quit.

If you thought vaping was a healthy alternative to smoking, think again. Researchers are still learning about the long-term health effects of e-cigarettes, but they may contain as many, if not more, harmful chemicals than tobacco cigarettes.

Avoid Pollutants

Among people with COPD who have never smoked, most are women. Women may be more vulnerable to indoor and outdoor air pollution. Women’s smaller lungs and airways mean the same amount of inhaled pollutants may cause more damage.

Working in places like nail salons, hair salons or dry cleaners can expose you to harmful chemicals. If you’re exposed to chemical fumes at your job, talk to your employer about ways to limit exposure. Better ventilation and wearing a mask can help.

Stay Current on Vaccines

People at risk for COPD are more likely to have serious problems resulting from some vaccine-preventable diseases. Ask a health care provider about getting vaccinated against the flu, pneumococcal disease and COVID-19.

Talk to Your Doctor About COPD

Women with COPD tend to be diagnosed later than men when the disease is more severe and treatments are less effective. If you think you could be at risk, or you are having symptoms, bring it up with your health care provider. Treatment can ease symptoms and improve your ability to exercise.

Learn More to Breathe Better

Find more information on COPD from NHLBI’s Learn More Breathe Better program at copd.nhlbi.nih.gov.