If the thought of high-intensity training fills you with dread, and burpees are a form of torture, then good news: the latest thinking in fitness is that it’s all about zone two. No, not the Tube map, but low-intensity, steady-state aerobic exercise performed at 60 to 70 per cent of maximum heart rate. Experts say this is optimal for heart health.
“Zone two is the sweet spot where your heart gets a meaningful workout without being pushed into stress mode,” says Dr Heeraj Bulluck, an interventional cardiologist at Leeds General Infirmary and author of Heart Reset 40: a Cardiologist’s Science-Backed Plan to Prevent Heart Disease Before it’s Too Late.
“At this intensity, your heart learns to pump more blood with each beat which means that over time, it doesn’t have to work as hard at rest or during everyday activities.” When done consistently, exercising within zone two causes your resting heart rate to drop, which “is one of the strongest markers of cardiovascular fitness and longevity”, Bulluck says.
The interest in heart rates has come about thanks to personal fitness trackers that allow you to monitor your pulse as you exercise. There are five zones for heart rate training: five is for the most vigorous effort, at 90 to 100 per cent of the maximum rate; one is for warm-up and recovery, at 50 to 60 per cent.
“In zone two, your heart is working at a pace it can sustain comfortably for 30 to 60 minutes or longer, helping it to build endurance and efficiency,” Bulluck says, whereas in zone four or five, “you are at or near your maximum heart rate. Your body relies much more on anaerobic metabolism, meaning your cardiac output surges, blood pressure spikes and your heart is under significantly more mechanical stress.” Zone two is the foundation, zone five is the peak. Bulluck says: “You need the foundation to support the peak safely.”
So, how to do it? First, calculate your maximum heart rate. While professional athletes are tested, for the rest of us it’s an estimate. Most people use the formula of 220 minus their age — so for example, if you’re 50, your maximum heart rate is roughly 170 beats per minute (bpm), meaning it should fall somewhere between 100 and 120 bpm during zone two training.
“The easiest way to monitor this is using a heart rate tracker like a smart watch or chest strap,” says Nancy Best, a personal trainer and founder of Ladies Who Crunch, an online fitness programme. Don’t get too stuck on the numbers, though. “All of these trackers are indicative, rather than definitive,” says Best, who suggests another good sign is “being able to maintain a conversation during the exercise. That’s a solid indication that you’re in your zone two range.”
Nancy BestISABELLA SMITH
Zone two exercise can include a brisk incline walk on the treadmill, a light jog, swimming, bodyweight circuits or a session on the cross trainer, StairMaster or rowing machine. The type of exercise doesn’t matter, so long as you’re able to sustain it within zone two.
That’s not always as easy as it sounds. Keeping the heart rate down “is one of the most common challenges, especially for beginners”, says Bulluck, so if you see it creeping up, slow your pace, even if that means walking intermittently throughout a run.
“Zone two is about the physiological response, not the specific activity,” he says. “For many people, especially those who are newer to exercise or returning after a break, a brisk walk will fall into zone two while a slow jog might already push them into zone three or four. Over months of consistent training, you will notice that the pace you can sustain at that heart rate gradually increases. That is your cardiovascular fitness improving in real time.”
The importance of zone two exercise has always been known among endurance athletes but for the public it’s a newer concept. “There’s been a shift towards training approaches that are more sustainable and repeatable,” says Luke Worthington, a sports scientist and personal trainer. “High-intensity work has its place, but it’s fatiguing, carries a higher injury risk and typically requires rest days to recover.”.
Zone two is particularly beneficial for those in mid-life because of what Bulluck calls “the decade of opportunity. The cardiovascular system is still flexible enough to respond to training, but risk factors are beginning to accelerate.” Consistent zone two training during this time can stave off those risk factors, he says.
For everyone, the long-term benefits are “profound”, says Bulluck, from improved cardiovascular fitness to lower blood pressure, a rise in “good” cholesterol and a fall in triglycerides, a type of fat that stores unused calories.
“Your body becomes more efficient at burning fat and managing blood sugar, which reduces inflammatory damage to your arteries,” he says. “At the cellular level, your mitochondria multiply and become more efficient, which supports everything from energy production to healthy ageing.
“Cardiorespiratory fitness is now recognised as one of the strongest modifiable predictors of how long and how well you will live. And zone two is the most accessible, sustainable way to build it.”