We all know that cardio exercises are good for heart health. We have all felt our heart beat faster when our body starts working harder too, but how exactly does this do us good?
It’s all about getting oxygen to the muscles
Working muscles need oxygen to be able to convert glucose into energy efficiently. If no oxygen is available in the cells, then this causes two problems. Firstly, it isn’t possible to produce much energy from the breakdown of glucose. Secondly, lactic acid builds up in the muscle which causes pain (“the burn”) and soon stops the muscle from working.
Adaptation – the key to all fitness
All improvements to fitness come about because the body adapts. If your body has to do something it isn’t used to, it makes itself more able to cope next time. Oxygen is delivered to the working muscles by the red blood cells. When the muscles need more oxygen, the heart has to pump more blood around the body. This means it has to work harder than usual by beating faster. Over time, it adapts by becoming bigger and stronger. It can then pump more blood with each beat and therefore deliver more oxygen to the muscles.
A more efficient heart doesn’t need to work as hard
The more blood the heart pumps with one beat, the slower it needs to beat and the less strain it is under. Although exercise temporarily raises the heart rate, the long term effect is that the heart rate is lower.
Best cardio exercises for a healthy heart
The best sort of exercises to do for a healthy heart are cardio exercises like running, cycling, swimming – ones which involve repetitive movements of the large leg muscles. To improve heart health, the activity should raise your heart rate and make you feel slightly out of breath – but not so much that you have to stop.
High intensity exercise
There have been several research studies in recent years which conclude that short bursts of very high intensity exercise are as beneficial to cardiovascular fitness as longer sessions of more moderate exercise. There are a few important points to be aware of if you are thinking of trying high intensity workouts
- This sort of exercise is only suitable for someone who has a healthy heart to start with. Someone who has been advised to take exercise for health reasons should not do high intensity exercise
- Working at high intensity increases the risk of injury. Intensity can only be increased by adding speed and/or resistance, both of which increase the forces on muscles and joints. Excellent exercise technique, good levels of muscle and joint flexibility and good balance are all important when working at higher intensities. It’s unlikely that the inexperienced exerciser will have any of these and so longer workouts at lower intensities are more suitable for beginners.
- Improvement to cardiovascular fitness is not the same thing as weight loss. The body can’t use fat as a fuel during high intensity exercise – it has to use carbohydrate. There is an argument that the body will break fat down following exercise to replace the carbohydrate used for the exercise. This isn’t scientifically proven and would depend in any case on not eating carbohydrate following exercise. The “high intensity for weight loss” craze has, for the most part, failed to produce good results.
Planning a cardio program
Any activity that raises your heart rate and makes you feel warmer and breathe more heavily is good for heart health. The World Health Organisation recommends 75 minutes a week of moderate intensity exercise. Ideally, you should do this in sessions of 20 minutes or more. If this isn’t possible, shorter sessions are still beneficial. Good activities include:
- Brisk walking
- Cardio machines (treadmill, cycle, cross-trainer, rowing machine etc)
- Rope skipping
- Cardio exercise classes
- Circuit training
See the Lose Weight Walking program for a complete 6 week walking cardio fitness program, with exercise schedules and logs.