Running as an activity couldn’t be any more straightforward: put one foot in front of the other at speed until you stop, either voluntarily or because you can’t go any further. However, the effects of running on the human body in both the short and long term are a much more complicated affair. Running is most known for its effects on our cardiovascular systems, but it also has an impact on:
- Cognitive function.
- Muscle development.
- Bone density.
The Body When Running
The human body’s functions change in different stages throughout a run. From the initial warm up, through to keeping a maintenance speed and the cool down, our body responds to these separate phases in distinct ways that experienced runners should be familiar with.
At the beginning of the run, the body will begin to start generating adenosine triphosphate (ATP) to help fuel movement. ATP is stored within glycogen, which itself is secreted within in muscle tissue and blood. Your body converts the food you eat into glycogen so that your muscles have a readily accessible store of energy to fall back on when we physically exert ourselves. As we run, ATP is unpacked from our glycogen reserves and gives our muscles the energy to keep us moving.
As you keep running, your leg muscles will start releasing lactic acid to relay to your brain the fact that you’re engaged in intense physical activity. As your muscles continue to break down glucose for energy, they require more oxygen to function. Your body responds to this by diverting oxygen away from organs related to immediately non-essential functions – such as digestion – increasing the flow of oxygen to your heart, lungs and legs. To deliver more oxygen to your respiratory system, your breath will start getting heavier, although the degree to which this happens will be heavily reliant on your overall fitness. Calorie consumption also increases as your body starts working harder. Your blood vessels will start expanding to help bring blood nearer to the surface of your skin to help cool down your system, as your core body temperature rises under the pressure of physical exertion.
If you’ve been running at a steady pace on a regular basis for a sufficient amount of time, you’ll find your body should settle into a sustainable cycle of sweating, breathing and energy conversion. For people whose bodies are unused to regular running, the processes of energy use won’t be as efficient as the body struggles to supply sufficient amounts of ATP to the legs. Common symptoms of this kind of strain include increased buildup of lactic acid, muscle ache and breathlessness. At this point maintaining pace becomes especially gruelling (although by no means impossible).
Having achieved the desired time or distance for the run, most people will slow their pace (often to a walk) and bring the body into its cool-down phase. During this time breathing will normalise, sweating will taper off and the heart rate will begin reverting to normal levels. As the pain of exertion goes away, we’re left with an endorphin high that will provide a mood boost for some time.
Short Term Effects of Running
There are some benefits to running that can be enjoyed immediately after a single session. Levels of positive neurotransmitters such as serotonin, norepinephrine and endorphin all help to improve mood, alertness and concentration, helping runners feel clear-headed and upbeat. These effects are one of the reasons running, amongst other exercises, is recommended to alleviate feelings of anxiety or depression. Another benefit is a boost to our resting metabolism that can result in faster calorie burning and increased function throughout the day. For beginner runners, leg shaking, nausea, light-headedness and headaches can sometimes occur, although usually only in cases of overexertion. These negative feelings will start disappearing after the cool down as the body’s systems revert to normal levels of function, and lessen as one runs more regularly.
Long Term Effects of Running
Whilst the short term benefits of running can feel great, the real gains are accumulated over a long term period, as the health benefits start to stack up and our bodies adapt to become more efficient at functioning under the physical stresses running exerts on our bodies.
The more we run, the better our bodies become at converting energy needed to keep us moving. There are many benefits to the function of our vital organs. Our heart becomes strengthened through having to pump more blood for the duration of the exercise. Whilst this helps our endurance in physical activity, it can also help our bodies function more efficiently even when we’re not straining ourselves. Our breathing capacity goes up as our bodies become better at processing oxygen, and our blood vessels become more flexible and improve capacity, helping stave off the dangers of hardened arteries and help keep our blood pressure at a safe level.
Although the effects of running on our brain is most noticeable in the short term, studies suggest that there are long term benefits to be had as well. Sustained exercise over a long period leads to changes in our brains and is said to be tied to everything from having a better memory, to lowering the risk of degenerative diseases like Alzheimer’s, and improving overall mental agility.
As we run, our leg muscles develop microtears under the strain of running, which then regrow in bigger quantities during recovery, leading to muscle growth. After a certain point, muscle development usually plateaus as the leg muscles become sufficiently developed to meet the needs of a particular pattern of running activity. Running can help improve flexibility, however, and helps raise the overall body temperature, making it a great warmup for other activities.
Bone Density & Joint Health
The impact running puts our bodies through is unusual amongst other cardiovascular activities. Whereas exercises like swimming and cycling are very low impact, the act of slapping feet on the road can cause tiny fractures in our bones that, much like muscles, recover in greater amounts. This leads to bones that are stronger and harder to break. Running can have an improvement on your joint health as well, helping the development of small groups of muscles around your joints and cartilage that help support your overall movement and agility, and can help with improved balance. On the other hand, cracking joints can become noticeable, especially in older runners. This condition, crepitus, occurs when cartilage between bones starts aging and becoming less effective. Weak quad muscles can exacerbate this condition, so runners should look at maintaining proper form throughout their run and consider a course of squat exercises to strengthen the muscle groups around these joints.
Running provides tangible benefits for anyone prepared to run regularly and build up their endurance. It can help people lose weight and stay fit, and help keep our heart and lungs healthy, lowering the risks of conditions like heart disease and high blood pressure later in life. The benefits for the brain, joints and so on are also not inconsiderable. All it takes is a pair of running shoes, and runners can choose to tailor their times and speeds to whatever level of exertion that they’re comfortable with. When combined with a program of weight lifting or calisthenics, it provides the foundation for a completely balanced fitness routine and a longer, healthier life.