Strength training and cardio exercise affect the body differently, not only in the obvious ways – building muscle versus developing cardiovascular fitness – but at a hormonal level too. This is the topline finding of a new study by the University of Copenhagen.

At face value, this may not seem overly surprising: these are, after all, two very different methods of training. But although logically we might have expected this to be the case, in fact the evidence hasn’t historically been there to prove it; surprisingly little has been known to date about the contribution of specific forms of exercise to the overall health benefits of being active.

The Copenhagen findings, recently published in the Journal of Clinical Investigation – Insight, are therefore significant and worthy of a closer look.

A metabolic boost

So what did the researchers discover? One key finding for all you cycling enthusiasts out there is this: cardio training on an exercise bike causes an increase in the production of the hormone FGF21 that’s three times as large as the increase observed from strength training with weights. And that matters, because FGF21 has a number of positive effects on our metabolism.

Let’s first take a step back and look at the FGF family of hormones in general, which are involved in a variety of biological processes including cell growth, morphogenesis and tissue repair. Within this, FGF21 – a hormone secreted by the liver – has been shown to act as a metabolic regulator that plays a role in controlling glucose homeostasis, insulin sensitivity and ketogenesis. Indeed, treatment of animals with FGF21 has been shown to result in increased energy expenditure, use of fat and lipid excretion.

It’s therefore hugely important to discover that indoor cycling significantly increases the level of this hormone in our blood.

The power of cardio

A quick word about the methodology of this randomised crossover study. The researchers took 10 healthy young men, randomly divided into two groups. All 10 men did both forms of exercise – cardio and resistance – once a week, with enough time between workouts to keep results distinct. The subjects also fasted overnight before all workouts, to ensure hormone levels were not impacted by food intake.

Both types of workout lasted for 60 minutes and were relatively tough: the cardio workout involved cycling at 70 per cent of VO2 max, while the strength training workout consisted of five exercises – each repeated for five sets of 10 reps – that worked all the major muscle groups.

The impact of the workouts was then measured by taking eight blood samples from all participants: pre- and post-exercise, plus six more samples over the following three hours. The researchers monitored levels of blood sugar, lactic acid, various hormones and bile acid in the body over this total four-hour period.

And the findings were notable. Specifically in relation the cardio workout, the researchers observed a significant increase in FGF21 production; there was no significant change in levels of this hormone in response to strength training. In addition, the researchers observed a robust increase in plasma glucagon preceding the FGF21 increase. This suggests that a fairly intense, 60-minute cycling workout can result in the co-ordinated regulation of FGF21 and glucagon – a hormone formed in the pancreas which promotes the breakdown of glycogen to glucose in the liver.

In contrast, glucagon concentrations were unchanged after strength training, and gradually declined during the three-hour recovery period.

“FGF21’s potential as a drug against diabetes, obesity and similar metabolic disorders is currently being tested, so the fact that we are able to increase the production ourselves through training is interesting.”

Exercise versus drugs

“We’ve known about the effects of various forms of training on more well-known hormones – like adrenalin and insulin – for a long time, but the fact that strength training and cardio exercise affect FGF hormones differently is new to us,” says Christoffer Clemmensen, associate professor at the Novo Nordisk Foundation Center for Basic Metabolic Research, and one of the researchers behind the study.

“Endurance training on a bicycle has such a marked effect on the metabolic hormone [FGF21] that we now ought to take a closer look at whether this regulation of FGF21 is directly related to the health-improving effects of cardio exercise.

“FGF21’s potential as a drug against diabetes, obesity and similar metabolic disorders is currently being tested, so the fact that we are able to increase the production ourselves through training is interesting.”

A solid foundation

The researchers point out that their results are limited by the fact that blood samples were not taken more than four hours after training – the longer-term impact was not measured. Neither are they able to comment on the effects of a full training programme on the FGF hormones.

Nevertheless, the results are so significant that they provide a solid foundation for further research, including whether similar effects can be seen in other population groups based on sex, age and metabolic status.

For now, the take-away is this: if you want to boost your metabolism and burn fat… get on your bike!

Over recent years, there has been a paradigm shift in the way society has approached dementia.

Previously, options for the care of those with serious cognitive issues were limited, with daycare centres or full-time care homes catering for older people really the only choices. However, the latest research findings suggest a more active approach is needed – one that focuses not just on palliative care within care homes, but on rehabilitation and improving the quality of life for dementia sufferers.

A rehabilitative approach

Even though dementia is a progressive disease with no cure, many treatment centres have therefore begun to introduce a rehabilitative element into their treatment of dementia – and physical activity is an important part of this.

A number of studies have found strong correlations between brain health and levels of physical activity: inactive people have an increased risk of dementia, while on the other hand, regular physical activity can slow – and even reverse – cognitive decline. Among those already suffering from dementia, exercise can also enhance some cognitive functions and improve quality of life.

inactive people have an increased risk of dementia

Studies suggest this is due to the excretion of the neurotrophic protein BDNF (Brain Derived Neurotrophic Factor) during exercise. BDNF plays an important role in maintaining our nervous system, including the formation of new nerve cells and nerve connections. Excessively low levels of BDNF are thought to be one of the causes of Alzheimer’s disease.

The Danish National Health Service has therefore produced a training guide for people with dementia, including suggested training activities and practical advice. Its recommendations around the level of physical activity are very similar to the recommendations made to the public as a whole: 30 minutes’ activity a day, including at least 20 minutes’ high intensity exercise twice a week.

In combination with other types of intervention – cognitive training, music therapy, sensory stimulation and so on – this level of activity is able to help alleviate the symptoms of dementia, and thereby improve people’s quality of life.

The positive impact of cycling

In practice, indoor cycling is often the chosen activity for dementia sufferers, as it requires no advanced skills and can be performed even by those with a severe degree of dementia.

We have to help people live with dementia, not just suffer from it.

In a recent Danish study – ADEX – researchers took a group of 200 people with Alzheimer’s. They were asked to train three times a week, for 16 weeks, with each session comprising one hour of moderate intensity indoor cycling.
The study showed these cycling sessions had a significant and positive effect on wellbeing and people’s quality of life, with a clear dose-response to exercise frequency and intensity: the subjects who exercised most, and hardest, experienced the best results. These positive results were not only physical, but also cognitive.

Similar results were also observed in a meta-analysis of 30 studies – a total of 2,020 subjects – with significant improvements noted in cognitive function as a result of exercise.

Furthermore, working out in small groups – with the social interaction that brings – has a positive impact on the effect of the training.

An interdisciplinary approach

In Frederikshavn Municipality, Denmark, we’ve therefore been putting together a programme to help citizens with dementia, seeking to improve their quality of life.

Over the last five years, a specialist team has been working together as part of this multi-disciplinary project – a team that consists of dementia co-ordinators (nurses with diploma-level education in dementia), a music therapist, an occupational therapist, a physiotherapist (myself) and a psychologist.
We work both independently and as a group, helping local citizens suffering from all forms of dementia – both mild and more difficult cases. Operating out of activity centres, care centres and people’s own homes, we not only work directly with dementia sufferers, but also offer a number of services to the relatives of those with dementia.

We have, for several years now, based our approach on results from proven studies. Given our focus on rehabilitation, physical activity – such as indoor cycling – plays a key role in our programmes. We clearly see that this enhances people’s physical functionality, social life and overall quality of life.

However, although a lot of research from around the world has already observed a positive impact of physical activity on cognitive function, within our own programme the impact of exercise on cognitive function remains unclear.

This is why our team is now planning a pilot project, starting at the end of this year. We will encourage local citizens with mild dementia to take part in indoor cycling sessions, and will monitor its impact on their cognitive functions – functions such as maintaining attention, remembering, learning and solving problems. The project will last a period of 14 weeks, with three weekly sessions – each session being one hour of indoor cycling, done at an intensity equivalent to 75 per cent of HR max.

Our aim is to prove and clarify the impact of aerobic exercise, such as cycling, on cognitive function – and, of course, to establish whether such an offer is attractive to the participants. Ultimately, the more we can do to improve people’s lives, the better. We have to help people live with dementia, not just suffer from it.

DEFINING DEMENTIA

Dementia is an overall term that describes a group of conditions, marked by a decline in mental abilities severe enough to interfere with daily life. The term ‘dementia’ covers not only impaired memory, but also other symptoms such as reduced initiative, orientation, language, language understanding and motor skills. And there’s still no cure. All that can currently be done is alleviate the symptoms, and sometimes slow the decline, through medication… and exercise.

10 key signs of dementia are as follows:

1. Memory loss, disrupting daily life
2. Difficulties in planning or solving problems
3. Finding it hard to complete familiar tasks
4. Losing track of date and time
5. Trouble understanding visual images and spatial relationships
6. Problems with words, both speaking and writing
7. Misplacing things and losing the ability to retrace steps
8. Diminished or poor judgement
9. Withdrawal from work or social activities
10. Change in mood and personality