The secret to running is a secret. Many think running only enhances body physical functions, but as scientists have found out, it boosts the development of the brain as much as it ‘nourishes’ your body.Dr Rachna Pande, a specialist in internal medicine at Ruhengeri Hospital, says running is helpful not only as physical exercise but has multiple benefits for the whole body, including the brain. "Being an aerobic exercise it improves uptake of increased oxygen by all body cells including brain cells,” she says. "This helps in better functioning of brain cells and helps in preventing degeneration of brain cells with aging. There is definitely more blood supply and more nerve cells formed. It makes one feel fresh as carbon dioxide and harmful chemicals are removed from blood. The release of positive neurochemicals is stimulated, thus providing sense of relaxation and well being to the individual.”  The specialist in internal medicine says this helps an individual to have a sharper memory; he can focus on his work with greater concentration. Studies have proved these benefits of regular running in individuals who run in contrast to those who do not run. The physical stamina of those running is also more than others. The Runner’s World, an online magazine, last month published an article that said scientific studies have proved that running stimulates the creation of new nerve cells and blood vessels within the brain, an organ that tends to shrink as a person ages. Also, they say, studies have shown that running may help increase the volume of the midbrain (which controls vision and hearing) and the hippocampus (which is linked to memory and learning). In addition to preventing or reversing age-related shrinkage, running affects brain chemicals in a way that sets runners up to have healthier-than-average brains later in life, they wrote.  According to the writers, another 2012 study also found that moderately fit people did better on memory tests than those who were less fit (or not fit at all). Among others, the editors say, exercise promotes the release of the feel-good chemicals called endorphins. Additionally, "like many antidepressant medications, running helps your brain hold on to mood-boosting neurotransmitters serotonin and norepinephrine.”"For best results, run in quiet, green spaces instead of on crowded streets -- a study last year found people in parks experienced brain activity similar to that seen during meditation, while people on streets experienced frustration,” reads the article. The only thing to be cautious about is, Dr Pande warns, people should not strain themselves while running.  Running on tarmac/concrete is bad for the jointsDr Alex Buteera, an orthopedic surgeon at Rwanda Military Hospital, says running on tarmac may have an effect on your knees and ankles "due to repetitive impact on the joints.” "The best way to avoid this is to run on softer surfaces like grass,” he says.  According to the Runners’ World, the beauty of running is that you can run on just about any surface, anywhere, as long as you have feet. However, be warned–not all surfaces are created equal–"because of the different impacts involved and the stresses which make their way up to your joints.” Physiotherapist Jean Damazcene Gasherebuka, at King Faisal Hospital, Rwanda, corroborates this hazard with more insight. Gasherebuka particularly warns ignorant folks he regularly sees on the streets of Kigali, especially on weekends, that are in danger of suffering from osteoarthritis, a painful joint inflammation that results from cartilage degeneration.How does it happen? Gasherebuka says when you run on whatever surface, or even when walking, the weight of your body applies a force, called the joint reaction force (JRF), on the ground because of the force of gravity. This force goes down to the knees up to the ground. The ground also applies an opposing force called the ground reaction force (GRF). Normally, this GRF must be equal to your weight, says the Physiotherapist. The GRF is the force exerted by the ground on a body in contact with it. "But when you step in mud, for example, or on any other very soft ground, the ground reaction force is poor. Whenever you run on hard ground, like on a tarmac road, the JRF increases because you are running on a hard surface which applies force from down, upwards,” Gasherebuka said.  "With time, you start getting knee injuries and pain, especially because this is where the counteracting force passes. This is essentially where the danger lies. This is not a problem you will feel after one or three running sessions. It comes with time. You damage your cartilages, with time, and then develop a bad and very painful but often avoidable condition called osteoarthritis.” "After a few years, one starts getting this terrible knee pain. My advice is that people over 40 should not run on hard surfaces like tarmac or concrete. I would recommend running on grass,” says Gasherebuka. --------------------------------Top running surfaces GrassAt its best, the grassland of parks, golf courses and football pitches provides the purest, most natural surface for running. While grass is soft and easy on the legs in terms of impact, it actually makes your muscles work hard. This builds strength and means you will notice the difference when you return to the road. However, most grassland is uneven and can be dangerous for runners with unstable ankles. It can also be slippery when wet, runners with allergies may suffer more symptoms, and its softness can tire legs surprisingly quickly. Woodland trailsFor a run that mixes constantly-changing surroundings with near-ideal running surfaces, head for your local woodland. Soft peat is God’s gift to runners, trails are usually quite level, and in some forests they go on for miles. They can sometimes be rather muddy, though. But unless you’re lucky enough to find wood chips or well-drained peat, woodland trails can be muddy and slippery. Tree roots can be a hazard for unwary runners. TreadmillWhen the weather’s bad, a treadmill is the best indoor running option for most runners. Most treadmills have monitors that display incline, pace, heart rate, calories burned and other data. The hardness of the running surface varies between machines. However, Effectively running on the spot isn’t very exciting, and if you don’t concentrate on keeping up your pace, you could be unceremoniously dumped behind the machine. Without the benefit of a natural breeze, treadmill runners tend to sweat profusely.SandSand offers a run with a real difference. If it’s dry and deep, you can give your calf muscles the work-out of their life without risking any impact damage to your joints. Sand gives an opportunity to run barefoot in a pleasant environment. Running through dunes provides good resistance training and strengthens the legs. But despite being great for building leg strength, the softness of the sand means a higher risk of Achilles tendon injury.