These stories make headlines and strike fear in the hearts of runners who read them. Athletes, often young and seemingly healthy, die suddenly at races, during training runs, or in the off hours between them.
Often, the cause is a sudden cardiac arrest, which is when the heart stops beating. It occurs because of a short circuit in the electric impulses that govern the heartbeat. When the heart stops beating there is a stark decrease in the effective blood flow of the body and any delay in treatment causes death.
A cardiac arrest is different from a heart attack, in which a blood clot physically blocks blood flow in an artery of the heart. Although a heart attack might be a cause of a cardiac arrest, both aren’t one and the same.
So, what could be the reasons which could cause the heart to suddenly stop beating?
Every athlete has her/his unique capacity of training intensity, which serves as a baseline for planning the individual’s aerobic, intense, endurance and recovery workouts. It is very important for the athlete to understand what her/his capacity is, how much time she/he would be able to tolerate low, moderate or high intensity workouts. Training within this tolerable range gives immense progress in weight optimisation, strength, stamina, flexibility, speed, power and fitness. Multiple body systems and processes play a part in synchrony in bringing about these changes.
Problems occur when this capacity is breached. When intensity is more than tolerable, heart rate shoots up -> heart gets weaker -> pumps less efficiently -> less blood flow (and less oxygen) gets delivered to vital organs (including the heart muscles) -> protective synchrony ceases to act -> cardiac arrest.
Are some athletes already at risk of developing cardiac arrest?
Male athletes, athletes over 40 years of age, smokers, short sleepers, individuals with a history of cardiac ailments, history of Diabetes Mellitus or High Blood Pressure, athletes with a higher resting heart rate are all at risk of potential cardiac arrest during phases of overexertion and at higher workout intensity zones. It becomes very important for athletes with the above risk factors to be aware of themselves and to be sure to train within their tolerable intensity zones.
So, how does one understand which is a safe intensity zone for endurance running (or long distance running)?
There are generally two ways most athletes estimate or measure intensity of training; a subjective method – RPE or Rate of Perceived Exertion and an objective metric – Heart Rate (HR). RPE is a metric that takes a great deal of time and experience and awareness of self to develop, usually used by more advanced athletes. HR is an easier objective metric available to most runners, and much more widely used.
Firstly, we calculate the maximum heart rate achievable.
Max HR = 220 – Age in years (earlier used for all, but of late, only for male runners)
For female athletes; Max HR = [206 – (88% of Age)] OR [206 - (88xAge/100)]
We must remember that this is a rough calculation for guidance and may not be an actual measurement of max HR. Max HR helps us calculate an individual’s HR intensity zones.
Zone 5 = >90% of Max HR
Zone 4 = 85-90% of max HR
Zone 3 = 80-85% of max HR
Zone 2 = 73-80% of max HR
Zone 1 = <73% of max HR
Intensity at zones 4 and 5 (> 85% of max HR) puts the athlete more at risk towards a cardiac arrest, especially in those having the previously mentioned risk factors.
How can we prevent a cardiac arrest from happening?
1.) Start low go slow. If one is a beginner or returning to running after a break or illness or if the previous night’s sleep has been disturbed, it is better to run shorter distances and in zones 1-2. In case of illness (even mild fever) it would be better to defer the workout.
2.) Sleep well. A good sleep pacifies the nerves. Allow for at least 6-7 hours of good sleep.
3.) Schedule at least one run per week targeting Zone 2 HR. This would help to build an aerobic base (stamina).
4.) Long runs, i.e., more than 45 – 60 minutes, should preferably be targeting Zones 2-3 HR.
5.) Zone 5 HR runs should better be planned as intervals of 30 seconds to maximum 5 minutes duration (of the active interval). The lower half of this range is to be used by amateur runners, the latter half by advanced runners without cardiac risk factors.
6.) Zone 4 HR runs (tempos or threshold runs) should not be greater than 30-minute sets.
7.) Anyone above the age of 40 years and with any of the cardiac risk factors should get their cardiac status evaluated and get a clearance by a doctor before embarking on an endurance training plan.
8.) People with diabetes and high blood pressure must have their sugars and BP well under control.
9.) Avoid smoking and late nights, strive for achieving a work-life balance.
10.) Do not compete with other runners, follow your own unique plan.
11.) Listen to your body while running. Do not overdo an activity. Any niggles including mild chest pain, increased breathing difficulty, cramps, unusual tiredness, jaw and neck pain, dizziness should warrant slowing down, walking or even aborting the workout / run. Get immediate medical attention if any of these symptoms are unusually more. Running despite these can cause life threatening complications.
12.) Before any run, especially a long run or intense run, do a proper warm up to help the heart acclimatize to the workout / activity.
13.) Consume adequate amounts of water to avoid overheating and dehydration. Ensure adequate replacement of salt and electrolytes and appropriate fluids to replace losses. Pouring water intermittently over the head and the entire body also can be a good idea.
Running is undoubtedly the most effective form of aerobic exercise and needs minimal investment, hence its popularity. However, it is important that the athlete is aware of the self and progresses gradually.
Do not neglect symptoms of chest discomfort, breathlessness, pain in the upper part of stomach or lower chest, palpitations (feeling one’s heartbeat} and dizziness/fainting spells. Go for regular health checkups to detect lifestyle diseases early.
It is better to have running arrest the disease rather than heart. Let us pledge to run safe, stay safe.
Readers can contact the author regarding Running tips, tricks, hacks & training on email: akashwin@gmail.com
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