Two weekends ago at Sunny Bay on Lantau Island, a place where many cyclists train and exercise, some fast-acting good Samaritans assisted a fellow cyclist at the side of the road who appeared to have suffered cardiac arrest. While the man, Philip, was not known to them, the actions of those few cyclists that day had an unquestionable impact on the lives of this man, his family and friends. [It is] more common ... for people to walk away, assuming that someone else can help The fact that Philip is alive and well - save for some short-term memory loss - is a miracle. I know this because I was personally involved in the incident. I had also been cycling in Sunny Bay and saw the state Philip was in when the ambulance arrived. He didn't look like he would make it. Sudden cardiac arrest kills more than 10,000 people in Hong Kong each year. As we go through our daily lives, rarely do we think about this small "workhorse" of a muscle in our chest that is tasked with pumping blood throughout our bodies ceaselessly from the time we are a few weeks old in the womb until the day we die. Our hearts beat about 100,000 times per day - about 2.5 to three billion times over an average lifespan. When cardiac arrest occurs, blood is not circulated to the brain, resulting in a person falling unconscious in a matter of seconds. If the condition is left untreated, brain damage may occur within a mere four to five minutes due to lack of oxygen. The longer the hypoxic condition, the greater the damage. This is why an immediate - and correct - response is so crucial. That Saturday on Sunny Bay, the first person to arrive on the scene found Philip lying unconscious on the side of the road. The man scanned the area for any immediate dangers to himself or the victim, and then proceeded to check the victim. The victim was motionless and unresponsive. The man quickly called 999 for help, during which another cyclist showed up some 30 seconds later. This man was familiar with cardiopulmonary resuscitation (CPR) and began administering chest compressions to Philip, which kept the blood and oxygen flowing. A third cyclist came on the scene a minute or so later, and declared that he too knew CPR and could assist. They continued CPR compressions until the ambulance arrived, whereupon it was quickly assessed that Philip's heart needed immediate defibrillation (an electrical shock to reset the heart rhythm). A shock was administered, the heartbeat was restarted, and Philip was rushed off to hospital in critical condition, still at risk of imminent death. The whole experience was not something out of a CPR course manual - it was real. Philip was most certainly on the brink of death. At this point, many readers might think that they, too, would help someone in need. However, it is actually more common than one might think for people to walk away from such a scene, assuming that someone else can help and even thinking, "It's not my business" or "I'd like to help, but don't know how". If the first passer-by had thought like this, Philip would have laid there while crucial minutes ticked by as his brain silently screamed for oxygen, until reaching a point of no return. The ambulance also arrived in the nick of time to administer the critical shock to restart Philip's heart. Had this not happened, Philip would have been rendered just another statistic. Thankfully, it didn't turn out that way due to the right timing and proper actions of the first responders - or maybe because of sheer luck. So what was the process that enabled Philip to get to the hospital with a better chance of survival? According to the American Heart Association, this "chain of survival" involves five steps: 1. Immediate recognition that a victim's heart has stopped, he or she is unresponsive and lacks normal breathing. Set the chain of survival in motion by calling 999. It's the same number for the police, fire services and ambulances in Hong Kong. 2. Early initiation of CPR, focusing on chest compressions at 100 compressions per minute. 3. Early defibrillation with Automated External Defibrillators that are available in ambulances but may also be found in some planes, shopping malls and sports centres. 4. Advanced life support in the ambulance and hospital. 5.Follow up post-cardiac-arrest care. For the sake of family, friends, colleagues or even strangers, everyone should familiarise themselves with CPR. It is easy to learn. In Hong Kong, you can take a simple course from the American Heart Association or Hong Kong StJohn Ambulance. At the very least, you can find some useful information or educational videos online. An amusing video advertisement by the British Heart Foundation on how to perform compression-only CPR, to the beat of the Bee Gees tune Stayin' Alive , has attracted a lot of attention and already made an impact on educating people and saving lives. Learn through whatever means you can, but don't walk away when tragedy strikes. A quick phone call and chest compressions can work miracles. firstname.lastname@example.org Dr Michael Tse is a sports science, strength and conditioning professional. He is clinic director of the Active Health Clinic of the Institute of Human Performance (IHP), University of Hong Kong, and was formerly head coach of strength and conditioning at the Hong Kong Sports Institute where he worked with world champions, Asian Games athletes and Olympians.