You’re standing outside waiting for a GPS lock. You haven’t taken a step, but in your brain a preparation process has already been triggered. ‘Your respiratory centre is found in an area of the brain called the hypothalamus,’ says Dr John Dickinson, Head of the Respiratory Clinic at the University of Kent. ‘It knows when you’re about to exercise, so you’ll unconsciously start breathing slightly faster and more deeply, and capillaries will start to dilate in anticipation of carrying more oxygen.’
As you set off, you need to consider how to help this natural response work effectively. ‘Starting slowly is key to allowing these processes to build up, rather than shocking the system,’ says Paul Hough, Lead Sport and Exercise Scientist at St Mary’s University Sports Performance Service.
Managing your early effort to allow your system the time to kick in is particularly important if you’re a new runner, or rebuilding your fitness after a layoff. ‘The fitter you get, the quicker your oxygen kinetics will kick in at the beginning of a run,’ says Dickinson. ‘This means that the shift between rest and producing enough energy aerobically will be quicker, so the breathless discomfort that comes at the beginning of a run will be over with more quickly.’
If you’re paying attention as you start to run you’ll notice a shift in how you breathe. At rest, you breathe primarily through your nose, but very soon into a run ‘you switch to mouth breathing, as it’s the easiest way to draw in air’, says Dickinson. Although this delivers more air to your lungs, there is a downside: When you nose-breathe at rest, air is warmed and humidified by your nose, but breathing through your mouth during exercise bypasses this process. This can cause problems, especially in winter. ‘Dry, cold air can be damaging to the airways because the nose can’t do its normal job of warming/humidifying,’ says Dickinson. ‘This means the lower airways in the lungs have to do it, which can lead to irritation.’ Over a long period, if you’re genetically susceptible and consistently run in very cold air, this could cause permanent damage to the lungs.
If it’s truly Arctic outside, consider wearing a scarf or bandana loosely across your face. ‘This warms the air before it goes down into your airways and also captures the moist breath coming out, which then humidifies the air going in,’ says Dickinson. ‘You can also avoid early runs in really cold conditions. The freezing, dry air of early morning will warm up and become moister later.’
Rhythm and power
As your run progresses, your breaths become more frequent and your heart rate rises. Your muscles now have a greater need for oxygen to facilitate the conversion of carbs or fat into energy, and as the heart and lungs are responsible for delivering this oxygen, they have to work harder. ‘At rest, your lungs will be taking in 10-12 litres of air per minute. When you run, depending on how big you are and how fast you’re running, this increases by four to eight times,’ says Alison McConnell, Professor of Exercise Science at Bournemouth University and author of Breathe Strong, Perform Better.
As things start to feel harder, breathing in rhythm can control the regularity and depth of your breathing, improving its efficiency and, in turn, boosting performance and lowering your perception of effort. ‘Break each phase of the breath into a number of footstrikes,’ says McConnell. ‘For example, begin your inhale on your left foot strike, continue it through the right footstrike, then exhale in the same pattern. You can experiment with what’s comfortable for you. This not only gives a feeling of control over your breath, it also encourages you to breathe deeply and slowly.’
That slower, deeper breathing will benefit your running. ‘Taking deeper, slower breaths will deliver more oxygen to the muscles than short, shallow breaths, as you’re taking in more air and expending less energy,’ says Dickinson. ‘But it should be a satisfying breath, rather than an excessively deep breath.’
After you inhale, oxygen-rich air travels down your trachea, on into two tubes called bronchi and then into smaller tubes called bronchioles, eventually reaching microscopic sacs called alveoli in your lungs. Our lungs have roughly 480 million of these and it’s through their walls – by a process called diffusion – that oxygen is delivered into your blood via capillaries. It stands to reason, then, that having more alveoli would improve your oxygen supply, but that’s not something you can achieve through training. ‘The lungs are not trainable and you cannot grow more alveoli,’ says McConnell. ‘But you can improve the muscles that inflate your lungs – mainly the diaphragm and intercostal muscles – so you can take more air into your lungs with each breath.’
You can train these muscles by practicing deeper, more efficient diaphragmatic breathing (‘belly breathing’) and through inspiratory-muscle training. Several studies on subjects using the popular inspiratory muscle-training device, Powerbreathe, found a 31 per cent improvement in inspiratory-muscle strength, 27 per cent increase in inspiratory-muscle endurance and up to seven per cent faster recovery during sprint repeats.
When that precious oxygen passes into your blood it hitches a ride on a protein inside your red blood cells called haemoglobin, which transports it to your quads, hamstrings and every other muscle that’s working to keep you moving. The more haemoglobin-loaded red blood cells you have, the more oxygen you can transport to your muscles. It’s that simple equation that has led many athletes into the dark world of stimulating artificial red blood cell production, most notably via the banned substance EPO. However, there are some safe and legal ways to maximise your haemoglobin levels.
‘Exercise in itself increases red blood cells to meet the extra demands on the body, but if you’re a regular exerciser, the body has probably already adapted to this increased load and you won’t see large increases once you’re fit,’ says
Dickinson. One way to shock the body into producing more red blood cells is by training at altitude (or in a similarly deoxygenated hypoxic chamber), but research shows this can take two to three weeks to take effect. That’s fine for elite athletes who ship out to high-altitude training camps for months on end, but not so practical for the rest of us.
Better news is that your diet can also help, with iron being crucial, as it’s an essential component of haemoglobin (see Foods to boost oxygen delivery, left). Iron deficiency can limit red blood cell production. ‘And in women, menstruation will also deplete them, so sufficient iron intake is vital,’ says McConnell. Women should aim to consume 14.8mg a day and men, 8.7mg.
Another factor to consider is breathing in carbon monoxide, which can impair performance by bonding with haemoglobin, thereby compromising red blood cells’ ability to transport oxygen to muscles. Carbon monoxide is present in cigarette smoke, and is also an environmental pollutant prevalent in vehicle emissions.
And carbon monoxide isn’t the only pollutant we need to be aware of as we breathe on the run. ‘It’s worth noting the scientific consensus is that the benefits of exercise outweigh the negative effects of pollution in healthy people,’ says Dickinson. But there are still negative effects to consider. ‘Our lungs try to protect themselves by producing more mucus to push invading particles back out, but they can’t fully defend themselves and pollution produces an inflammatory response in the airways,’ says Dickinson. ‘Frequent, long-term running in polluted air can lead to exercise-induced asthma, but it’s an issue of dose and how genetically susceptible you are.’
Dickinson believes air-filter masks can decrease the level of pollutants you inhale, but questions how practical wearing anything that compromises airflow is for runners and suggests alternative anti-pollution strategies: ‘To limit your exposure, avoid running next to busy roads, pay attention to air-quality forecasts and run at times when pollution is lowest.’ Pollution levels in the UK tend be lower before 7am and after 8pm. Ozone, another potential breathing irritant for runners, is highest on hot days in spring and summer.
Getting your five-a-day could help offset the effects. ‘Air pollutants injure the lung via oxidative mechanisms, which are controlled by antioxidant availability,’ says Frank Kelly, Professor of Environmental Health at King’s College London. ‘Some food components are powerful antioxidants, such as vitamins C and E, so fresh fruit and veg are thought to be beneficial.’
The pump card
Once your red blood cells have picked up their oxygen, they are pumped with their precious cargo around your body by your heart. And it’s here that you can make serious gains in terms of improving oxygen delivery. ‘Your lungs don’t limit your supply of oxygen, but the heart can,’ says Dickinson. ‘The bigger the volume of blood the left side of the heart can pump to your muscles with each beat [aka stroke volume], the more oxygen they’ll receive.’
That capacity of the heart to pump blood is vital for improving the endurance athlete’s holy grail – V02 max. ‘Think of V02 max as being like the size of a car engine,’ says Hough. ‘If your car can go at 120mph maximum speed, it can cruise easily at 90mph. But if it’s max speed is 100mph, it will struggle to cruise at 90mph. A high V02 max gives you a bigger capacity to go faster for longer. And the best way to improve it is by including sessions where you’re running close to, or at, your V02-max pace. As a rule of thumb, this is roughly the hardest pace you could keep up consistently for 10-12 minutes.’
When the oxygen-carrying red blood cells arrive at your working muscles, the haemoglobin drops off its load and the muscle uses it immediately to convert stored glycogen into energy to power your run. That energy is generated by your mitochondria, the powerhouses of your muscle cells. ‘Mitochondria need oxygen to convert carbs (and fat on longer, slower runs) into a molecule called ATP, which is the body’s energy currency,’ says Hough. ‘And it’s possible to both improve the ability of the mitochondria to convert oxygen efficiently and to increase their numbers.’
The key to seeing significant improvements in both your heart and mitochondrial function is variety in your training sessions. ‘Long, slow runs at a conversational pace increase the heart’s pumping capacity and its endurance,’ says Dr Graham Sharpe, Principal Lecturer at the School of Science & Technology at Nottingham Trent University. And long, slow runs also improve the ability of your mitochondria to burn fat as fuel, according to Hough. ‘This is particularly important for longer races, such as marathons.’
Short, intense interval sessions are very effective at boosting your heart’s ability to pump larger volumes of blood and improving your V02 max, and have also been shown to improve mitochondrial function, according to Hough. To improve V02 max, Hough recommends four to six four-minute intervals at a hard but not maximum pace, with three minutes of light jogging recovery in between. ‘The best sessions to enhance mitochondrial function would be all-out sprints for 10-30 seconds, with a rest period six times longer,’ says Hough.
A third element to add is resistance training. ‘Recent research has shown resistance training can also boost mitochondrial function,’ says Hough. ‘And stronger, more efficient muscle means that the heart and lungs don’t have to work as hard to deliver oxygen,’ says Dickinson. ‘Working on core and leg strength in particular can also improve running economy [how efficiently you use oxygen].’
At the same time as dropping off oxygen, your blood ‘picks up’ carbon dioxide, which your muscles produce as a waste product when triggering energy release. This is where that old runner’s foe, lactate, comes into play. ‘We produce lactate the whole time we’re running and our muscles can use it as fuel – it’s not a waste product,’ says Sharpe. ‘But we reach an exercise intensity where the rate at which we produce lactate exceeds the rate at which we can use it and it starts to accumulate in the blood. This is known as lactate threshold.’
Runners know all too well the effects of reaching lactate threshold; our breathing becomes harder, verging on desperate, as we gasp for air. But you may be surprised to learn what’s driving this: ‘It’s not to take in more oxygen,’ says Sharpe. ‘Your blood, even when you’re working at high intensities, is still saturated with oxygen – it can’t carry any more. You breathe harder because your body is trying to get rid of carbon dioxide and it does this because that’s the most effective way of controlling the build-up of acids [such as lactate] in the blood.’
‘You can delay this point by adding training sessions that take you just above your lactate threshold,’ says Dickinson. ‘Try hard one-kilometre efforts followed by a kilometre of active recovery. That way, you’ll be able to run for longer at a higher intensity before experiencing lactate build-up and its accompanying breathing discomfort.’
The unwanted carbon dioxide exits your body after diffusing through the walls of the alveoli into your lungs, which push it back through the bronchioles, bronchi, trachea and out of your mouth. So if the exhale is getting rid of C02, which is key to avoiding lactate build-up, is it best to breathe out as hard as you can? ‘No,’ says Dickinson. ‘Your exhale is a more passive process than the inhale, as it’s predominantly powered by your breathing muscles springing back. You should allow it to feel natural – forcing air out leads to a greater need to breathe in again, which can lead to hyperventilation.’ Fast, shallow breathing affects the balance of oxygen and C02 in the blood, and can cause dizziness and blurred vision. According to Dickinson, no matter how hard you try you can’t improve the maximum amount of air you expel from the lungs after a deep inhalation. So, exhaling naturally is the vital fi nal component of good, efficient breathing. All you need to do is inhale. And exhale. And so on…