Personal Training: Cardio-Vascular Intensity

Today’s fitness blog discusses cardio-vascular workouts and their role as a staple part of health and fitness training. For anyone working in the health and fitness industry or thinking of following a personal trainer course, it’s important to have an understanding of cardio-vascular intensity in relation to heart rate.

There are two ways of working out a person’s heart rate: maximum heart rate (MHR) and heart rate reserve (HRR), which is also known as the Karvonen method or Karvonen formula.

Maximum heart rate

Our maximum heart rate at birth is 220 beats per minute. For every year we age, our maximum heart rate comes down by a year, so a 30 year old would be expected to have a maximum heart rate of 190. However, variations such as genetics, lifestyle and fitness levels also come into play.

A personal trainer needs to be aware of how hard their client is working in order to set an effective training programme, which is why heart monitors are often used in the gym environment.

Heart rate and the intensity of training

Working at an intensity of 50%-70% of maximum heart rate would allow a client to lose weight and improve their general fitness and energy levels. It would also increase their bone density, strengthen their muscles and ligaments, lubricate their joints and improve their flexibility. To put someone through a more intensive workout that would make their heart pump harder, demand more oxygen and challenge the lactate system, a fitness instructor might work them at 70%-85% of maximum heart rate.

A new client who wants to burn a few calories and improve their fitness rate might be worked at 60% of their maximum heart rate. To work out how to train a 30 year old at 60% of their maximum heart rate, a personal trainer would apply the following formula:

220(maximum heart rate at birth) – 30 (age) x 0.60 (60%) = 114 beats per minute

The problem with this method is that it assumes that everyone age 30 has the same maximum heart rate, regardless of fitness levels and genetics. It is possible for a personal trainer to establish each individual client’s true maximum heart rate by working them maximally. However, this will put considerable stress through the heart, which is not recommended for the general population who come into a gym environment.
The Karvonen formula and RHR
This method measures Resting Heart Rate (RHR), which takes into account an individual’s fitness levels. RHR is most accurately measured first thing in the morning. An RHR of 50 indicates an individual who is fitter than someone with an RHR of 70. Their heart beats fewer times a minute at rest because it’s stronger: it has bigger chambers that can contract harder and pump out more blood per beat, supplying oxygen and nutrients to the muscles.

If a personal trainer has a 30-year-old client with an RHR of 70, they can calculate that individual’s maximum heart rate using the following formula:

220 (maximum heart rate at birth) – 30 (age) – 70 (RHR) x 0.60 + 70 (RHR) = 142 beats per minute (bpm)

The Karvonen formula is therefore a much more accurate way of administering intensity as it is more specific to the individual. A personal trainer will also link that to how the client feels while exercising: between 50-70% will be moderately comfortable, from 70-85% they will feel the effects of working a lot harder.

Working to increase VO2max / HRR

The maximum volume of oxygen an individual can take in and use while exercising maximally is referred to as VO2max and is measured in millilitres per kilo of body weight per minute.  VO2max and HRR are closely related and are often referred to as the same thing.  If a client is working at 60% of their VO2max they are also likely to working at 60% of their HRR – effectively 60% of their aerobic ability.
 
If a personal trainer works with a client to increase their VO2max, they will be able to increase the intensity they work at and sustain it for longer periods of time.

Monitoring intensity is a useful tool in fitness programmes such as interval training, but a personal trainer should also bear in mind that someone new to the gym may benefit more from starting at 50%-60% of their HRR and building up to a longer duration and more intensive training programme over time.

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