A strong handshake could indicate a healthy heart

Greater handgrip strength was associated with less cardiac hypertrophy and remodeling, which are indicators of long-term cardiovascular disease. The study's results could help identify those at higher risk for cardiovascular disease.

"Remodeling/hypertrophy, which may be easier understood as a form of reshaping of the heart muscle, is a type of disease that can lead to a weaker heart and that mostly occurs in older individuals," said Dr. Sebastian Beyer, an internal medicine physician in Boston and lead author of the study.

"The results of our study indicate that better muscular strength, as measured by handgrip strength, may be associated with fewer changes (reshaping) of the heart. Less reshaping of the heart is associated with fewer cardiovascular complications," Beyer added.

The research, published Wednesday in the journal PLoS ONE, compared handgrip strength with cardiac structure and function among 4,654 adults in the United Kingdom. Participants were men and women, aged 40 to 69, who were recruited between 2006 and 2010 in 22 centers across the country.

The researchers measured handgrip strength using a machine called a hydraulic hand dynamometer. They then analyzed the structure and function of participants' hearts using cardiovascular magnetic resonance or CMR, a rapidly developing technology that provides high-resolution images of the heart.

"CMR is an imaging technique that has also been used extensively to look at certain heart diseases -- many genetic -- among young people," Beyer said. "We have learned a lot about CMR imaging from that."

The researchers looked at six indicators of cardiac function, such as the overall mass of the heart, as well as a number of measurements assessing left ventricular function, including stroke volume, ejection fraction, end-diastolic volume and end-systolic volume.

The left ventricle is the portion of the heart that is primarily responsible for pumping blood throughout the body. Stroke volume refers to the volume of blood pumped per heartbeat, and end-diastolic volume is a measurement of the filling capacity of the left ventricle, according to Beyer.

The research team found that each one standard deviation increase in handgrip strength was associated with an increase in stroke volume, an increase in end-diastolic volume and a decrease in left ventricular mass.

Though handgrip strength has long been used as a quick, easy and noninvasive way to gauge cardiovascular functioning, this study is among the first to link handgrip strength measurements with actual structural changes in the heart muscle, according to Dr. Deena Goldwater, an attending cardiologist and geriatrician at the David Geffen School of Medicine at the University of California, Los Angeles, who was not involved in the study.

"Grip strength is a great metric. It's quick and easy to perform in the office, and the results are available immediately, unlike blood work or imaging," Goldwater said. "This paper is looking at subclinical changes in cardiac structure and function, meaning the muscle changes slightly in ways that can be measured with imaging, but individuals are not experiencing symptoms from these changes."

The precise pathway linking handgrip strength with cardiac function is still unclear, Beyer said. Some believe that reductions in both may be caused by dysfunctional proteins that build up in skeletal and heart muscle with age, while others believe that inflammatory chemicals may be responsible for decreases in skeletal muscle mass and in cardiac function.

In order to rule out any additional factors that could have influenced both handgrip strength and cardiac function, the researchers adjusted for variables such as diabetes, high blood pressure, physical activity, alcohol use and smoking status, Beyer said.

Participants who had a history of cardiovascular conditions were also excluded.

The researchers also separated participants based on age and gender. They found that while the association between handgrip strength and cardiac functioning did not differ between men and women, it did differ based on the age of the participants.

Specifically, the association between increased handgrip strength and increased ventricular functioning was stronger in younger participants, but the association between increased handgrip strength and reduced hypertrophy was stronger in older adults.

"It appears that the association of handgrip strength and certain reshaping of the heart was more pronounced among older individuals," Beyer said. "That could make it easier to see a difference in these age groups."

The study relied on a large, nationally representative cohort -- one of its major strengths, Beyer said.

However, because it was an observational study, additional variables may have impacted the outcome. Also the results may not be generalizable to populations with a vastly different makeup from the United Kingdom, according to Beyer.

"That being said, there are populations that are more similar to the UK, such as other European populations or the US," he added.

Ultimately, though, the findings do not dramatically alter professional advice on what to do to maintain a healthy heart, Goldwater said: "Eat a healthy and well balanced diet, exercise, get enough sleep, and manage stress with techniques such as meditation or mindfulness."