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The issue

There are a lot of people who are experiencing heart issues, when they are either training for or competing in long distance, endurance events, like marathons.

Even in professional sports, there are a lot of health professionals, who still focus on training plans, which evolve around training distances and/or duration, instead of training intensity.

For amateurs, adopting this mentality can result in major heart issues.

Therefore, I would like to share my knowledge about training for and competing in long distance, endurance events with you.

Focus on workout intensity

Workout intensity is indicated by your (average) heart rate during an effort!

Most runners are well above their capabilities when they are training for competing in long distance events, like marathons.

Focusing solely on distance or workout duration is VERY DANGEROUS, because it does not factor in your personal or daily performance level or the overall well being/ strain of your body.

Why I know

I am training 8 to 11 hours a week — mainly endurance (5 to 8h) with additional yoga and strength exerises — and have completed several endurance events, like transalps. During a transalp, you ride your mountain bike in steep and technical terrain for ~8h a day & 5 to 6 days in a row for 500 to 700km overall.

Intensity Levels

It is very important that you are staying within certain intensitiy levels, while training for and performing in long distance, endurance events.

The overall trick is to avoid shortness of breath at all costs, because it indicates that you are WAY OVER YOUR AEROBIC THRESHOLD.

Heart rate zones

When it comes to training intensity, you should learn about HEART RATE ZONES.

Heart rate zones are oriented on your Aerobic Threshold Heart Rate (THR):

Your aerobic threshold heartrate (THR) is ~80% of your max achievable heart rate.

Zone 1: RECOVERY => Range <70% of THR.
Zone 2: ENDURANCE TRAINING => Range: 70–87% of THR.
Zone 3: AEROBIC CAPACITY (TEMPO) => Range: 88–95% of THR.
Zone 4: LACTATE THRESHOLD => Range 96–100% of THR.
Zone 5: MAX => Range >100% of THR.

Note! Professional athletes, like Tour the France riders, are very strict in training and staying within these zones. Otherwise they would obviously die from excecssive strain!

Intensity during an endurance event

You should stay within or below heart rate zone 3 for 80%+ of the whole event.

When you are competing against others, you will obviously need to sprint/attack at some point.
Keeping your pace moderate for the major part of the event, will help you contain your power reserves for these final attacks.

Anaerobic Zone = Not Good!

When you stay above your aerobic threshold (> Zone 4) for an extended amount of time, your body enters the anaerobic zone.

In the anaerobic zone, your body switches to the lactate energy system, which uses carbohydrates as fuels and relies on anaerobic glucosis for the production of energy, called ATP (Adenosine Triphosphate).

In anaerobic glycolysis, the glucose is turned into lactic acid for the release of ATP.

Lactic acid and excessive strain are very bad for your muscles and heart.
They will hurt your ability to recover in the short term and will cause major heart issues in the long term.

You should only enter zone 5 for a short amount of time, for example, in dedicated sprint training, in order to push your overall anaerobic capacities.

My personal heart rate / training zones for reference

My heart rate zones look like the following (at age 34):

My max achievable heart rate is ~195 bpm.

Z1 : <109 bpm
Z2: 110–136 bpm
Z3: 137–148 bpm
Z4: 149–164bpm
Z5 >165 bpm.

Obviously, your heart rate zones will differ!

Training tips

Make sure that 2/3 of your overall training sessions are LOW INTENSITY = HR Zone 1 & 2.

This is what professional athletes do.

Include recovery sessions (HR Zone 1) the day after very hard efforts.

Recovery sessions supply your muscles with oxygen and boost overall recovery. Additionally, they help to clear out any lactate acid that might remain in your muscles.

Please get educated in these contexts before throwing yourself under the marathon bus!

Get professional help (trainer, coach, doctor) when you don’t know exactly what you are doing!!!

Visit a doctor and get your health checked before starting new adventures, like training for or performing in a marathon!

As a rule of thumb, you should be able to run ~60km+ at a stretch in order to really enjoy running a marathon (42.195km). Or ~30km+ for a half-marathon (21km).