Exercise: one size does not fit all

In this week’s article, we are reviewing current evidence that looks at why individuals should complete both resistance and endurance training, if they wish to see a positive response in both their strength and cardiovascular fitness.

The STRUETH (Studies of Twin Responses to Understand Exercise as a Therapy) study investigated the response ofVO2max and muscular strength to resistance and endurance training, in identical and non-identical twins. The paper further considers the role of genetics and environmental factors on the response to training by comparing the response between each set of identical and non-identical twins. Twin studies are used to eliminate some inter-individual differences and allow more direct comparisons between groups.

Each individual completed three-months of either resistance training or endurance training, followed by a three-month break, before completing three-months of the other intervention. Both exercise interventions consisted of 3 hours of training per week which increased in intensity progressively over the 12 weeks. Before and after each intervention individuals completed a number of tests to determine any changes in VO2max and muscular strength. Endurance was assessed through a 3-minute graded treadmill test to exhaustion, with heart rate, blood lactate and effort rating collected during each stage. A 1 rep max test – the maximum amount of weight you can lift for one repetition, for bench press and leg press was used to determine muscle strength.

What did the study find?

The study found that every individual responded to at least one exercise modality. 100% of individuals positively responded to the resistance training with an increase in strength over the 12-week period. As a result of the endurance training 86% of individuals had an increase in cardiovascular fitness. Furthermore ~50% of individuals responded to the non-training specific modality (strength increased following endurance, and cardiovascular fitness following Resistance). The results suggest that to guarantee a positive result in strength and cardiovascular fitness, you need to do both resistance and endurance training.

When assessing the difference in exercise response between identical and non-identical twins, it was found that genetics only contributed a small amount to how an individual responded to the training. The greatest impact was down to environmental factors, such as sleep and nutrition, which can be linked to why 20-30% of individuals may fail to exhibit beneficial physiological responses to exercise interventions that accord with guideline recommendations for health. Therefore, it is not only important to include both resistance and endurance training as part of your weekly routine, it is also vital to ensure that we are managing and adapting the environmental factors to maximise the benefits of your training and your results.

What can we take from this?

If we wish to achieve a positive improvement in strength and cardiovascular fitness, the best results are achieved by doing both resistance and endurance training. Just doing one or the other gives you a 50:50 chance of both improving. We aim to complete three hours of resistance training a week through your session with a CES.

Environmental factors are key in determining how we respond to our training. Monitoring factors such as nutrition, steps, stress and sleep through our 4 pillars and at the start of each session, allows us to ensure we know as much as possible to help you and give you the right tools to get the best response to your training.

Staying up to date with research and using evidence-based practice is a key part of CP+R’s exercise prescription. This study highlights the importance of using research to provide a general guideline, then customising prescription to each individual and their response. The assessment at CP+R offers a great opportunity to see how you are responding to your training and ensures that each program is specific to you and your individual goals.

On a slightly more trivial note, 10 sets of twins reported themselves initially as non-identical and it turned out they were identical!

Marsh, Channa et al (2020). Fitness and strength responses to distinct exercise modes in twins: Studies of Twin Responses to Understand Exercise as a THerapy (STRUETH) study. The Journal of Physiology