Men\'s Health Singapore - June 2017

moderate exercise or three 25-minute sessions
of vigorous exercise each week, plus moderate-
to high-intensity strength activities at least two
days a week.
Interval training – ramping up the intensity
for several minutes multiple times during your
workout – is excellent. It helps train the heart
and your muscles to work harder by enabling
enhanced oxygen delivery and increasing
muscle efficiency, says Dr David Wolinsky,
section head of nuclear cardiology at Cleveland
Clinic Florida.

IT SELF-ADJUSTS

Your heart rate is constantly changing, even

beat to beat. That’s because the heart is

governed by two competing halves of your

autonomic nervous system, says Dr Reginald

Ho of the Thomas Jefferson School of

Medicine. Your sympathetic nervous system

responds to threats with the fight-or-flight

response, which speeds up the beat. Your

calmer parasympathetic nervous system slows

things down so you can rest and digest.

The two are engaged in a constant tug-of-

war, says Dr Ho, depending on external stimuli

• and, crucially, your interpretation of those
  stimuli. A higher sympathetic “tone” means a
  more frantic heartbeat, higher blood pressure
  and a greater risk of cardiac events.
  But when the parasympathetic nervous
  system is dominant, as it is in athletes, the
  rate settles down and becomes more variable.
  This heart rate variability is actually a marker
  of good health, says Dr Ho. Less heart rate
  variability, by contrast, could indicate the
  presence of a chronic disease or, in an athlete,
  overtraining.
  fKeep the beatAppssuch as Elite HRV
  and Omegawave (both free) can help you
  monitor your heart rate variability. First, you’ll
  establish a baseline. Then you can check daily
  fluctuations so you know when to work out
  harder and when to back off, says Alexander
  Koch, a professor of exercise science at Lenoir-
  Rhyne University.

IT’S WIRED

When he was in medical school, Dr Ashley was

captivated by a unique property of the heart:

“If you remove it from the body and keep it

The Ticker

Timeline

HEALTH

supplied with energy and oxygen, it will

continue beating on its own,” he says.

That’s because the organ has its own

electrical system, with special cells that

generate and dispense regular, rhythmic

electrical pulses, stimulating the upper (atrial)

and lower (ventricular) chambers of the heart

to contract and relax. If some of those cells

conk out, others can take over.

But that electrical system is also vulnerable:

Problems with the complex nerves and trigger

cells that control heartbeat can go awry,

leading to rhythm disturbances such as atrial

fibrillation (AF).

Even worse is ventricular fibrillation, when

the signal becomes chaotic and the functional

heart contractions simply stop. “When that

happens, more than 90 percent of the time,

the result is death,” says Jeffrey Ardell, director

of the Neurocardiology Center for Excellence

at UCLA. Fortunately, scientists are developing

electrical therapies, such as vagus nerve

stimulation, to calm an erratic heart and reduce

the prevalence of AF.

fKeep the beat To reduce your odds of AF, lay

off the sauce. The Journal of the American

College of Cardiology reports that men who

drink alcohol daily have a higher risk of AF

• 40 percent higher if they have five drinks a
  day. Excessive alcohol consumption might
  temporarily slow certain heart signals,
  throwing the whole system out of whack.

IT HAS A BRAIN

The heart has its own neurons that are

clustered into nerve structures called ganglia,

almost like a rudimentary brain. “When you

transplant a heart, the little brain goes along

with it,” says Jeffrey. This “brain” can’t form

thoughts and memories, but its job is critical:

It ensures that your heart’s electrical and

mechanical functions work in tandem to

In Utero

You had a heart before you had a thought. It

began as a tube with four segments that folded

around itself to form a four-chambered organ.

Around day 21, an electrical impulse from a heart

muscle cell sparked your first heartbeat.

Infancy

Your heart muscle developed rapidly until your birth,

and you were born with all the heart cells you’ll ever

have. Then, at around seven months, your heart

began pumping significantly more blood to your

brain – and keeps at it to this day.

Childhood

The heart grows at the same rate as other body

parts, so it reached full size at the end of puberty.

Many of your heart’s functions peaked around this

time. Research suggests, however, that obese kids

have larger, less healthy hearts.

36 JUNE 2017 MENSHEALTH.COM.SG