Personal Training: Cardio-Vascular Intensity

Today’s fitness blog discusses cardiovascular workouts and their role as a health and fitness training staple. For anyone working in the health and fitness industry or thinking of following a personal trainer course, it’s important to understand cardiovascular 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 in genetics, lifestyle, and fitness levels also come into play.

A personal trainer must be aware of how hard their client is working 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 work out at 60% of their maximum heart rate. A personal trainer would apply the following formula to determine how to train a 30-year-old at 60% of their maximum heart rate:

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 everyone age 30 has the same maximum heart rate, regardless of fitness levels and genetics. A personal trainer can establish each individual client’s actual maximum heart rate by working them maximally. However, such an approach will put considerable stress on the heart, which is not recommended for the general population that comes into a gym environment.
The Karvonen formula and RHR
This method measures Resting Heart Rate (RHR), which considers 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 more potent: 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 clients to increase their VO2 max, they can increase their intensity and sustain it for extended periods.

Monitoring intensity is a useful tool in fitness programmes such as interval training, but a personal trainer should also remember 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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