Our New ARC Grant on Motor Performance and Ageing

If you thought turning 30 was bad, you're not going to like this. 

We lose more than 0.5% of our muscle mass each year after 30, which decreases our ability to run, jump, swim and perform virtually any motor task. Age-related muscle loss (known as sarcopenia) increases our risk of dying due to injury and even illness, as the proteins in our muscles are a major source of fuel for our immune systems.

Elderly sea gypsy weaves nets in Phuket, Thailand

Bike riding in Sri Lanka        Photo credit: Getty Images

Luckily, there's a simple solution to the problem: getting off the couch.

Exercise improves the efficiency of muscle metabolism and makes muscles more protein-dense, which helps slow ageing. We live longer, healthier lives. 

For humans, motor ageing affects the quality and length of life. But what about animals? In nature, motor function literally means life or death, as individuals have to escape predators and catch prey to survive. They also have to find mates to reproduce. They have to run over varied terrain, in the night or day, driving rain or blazing sun, with varied body sizes and shapes. Males may have dangling testicles, females may have dangling babies. And they have to do all this while avoiding catastrophic injury. 

Last week, our research team - A/Prof Robbie Wilson, Dr Diana Fisher, Dr Hamish Campbell, Dr Celine Frere and me - got a major grant from the Australian Research Council to study a critical aspect of animal performance: how an animal's habitat affects its motor development and ageing. 

Well-endowed male antechinus

Male antechinus

What does habitat have to do with anything? We believe that within a species, individuals living in more-complex (i.e. rocky or diverse or steep) environments will have better motor function and slower motor ageing than those living in simpler (flat or unvaried) environments. This will help them live longer and produce more offspring.

Over the next 3 years, we'll be testing these ideas on small mammals - including quolls and antechinus - both in the wild and in captivity. At our field sites, we'll use GPS trackers to understand how animals use complex versus simple habitats, and how this affects their motor performance, ageing and mating. At our research facility, we'll raise animals in complex versus simple habitats to measure differences in performance, muscle physiology and mating success between environments and over lifetimes. 

Our study will show how habitat use affects motor performance and ageing in wild animals, which is key to their conservation. But more than that, we hope to shed light on a new way of thinking about motor rehabilitation. Over 50% of elderly people will experience debilitating muscle loss in their lifetimes, yet little is known about how the complexity  of movement affects muscle quality.

So this is some of what we'll be doing these next few years! If you're interested in collaborating, volunteering or learning more, please get in touch - we'd love to hear from you. (amandacniehaus@gmail.com or a.niehaus@uq.edu.au)

*This post was originally published here .

From the field: Studying endangered northern quolls on Groote Eylandt

It's a new year, which means there's new research to be done as I delve into my PhD. But before I start writing about that, I want to write about a somewhat related experience I was lucky enough to have last year.

In August/September, I got to join my labmates Ami, Jaime, and Gwen up on Groote Eylandt, which is a large island off the coast of the Northern Territory owned and run by the Anindilyakwa people. The reason: to help them out with their research on the endangered Northern Quoll (Dasyurus hallucatus).

Catwoman, a pretty little female Northern Quoll (Dasyurus hallucatus). 

A classy addition to any accessory collection. Image credit: Wikimedia Commons. 

Now, if you’ve ever been to Australia, you probably have heard the story of the Cane Toad (Rhinella marina) – even if it’s just via one of the many delightful novelty souvenirs available in Australian tourist shops.

The cane toad is an extremely successful invasive species that was introduced into Australia in 1935 to eat a beetle that was negatively affecting the cane industry (which it didn’t), and since then it has spread down the East coast and across the Northern Territory, and is slowly making its way down the West coast as well. One of the reasons Groote Eylandt is so amazing is because it is one of the few areas up North that has remained cane toad-free. Because of this exclusion, it is the last stronghold population of the endangered Northern Quoll, whose numbers have been decimated via their predation on this toxic species. This makes Groote an ideal location to study the quoll in its natural habitat, as numbers are high enough for recapture studies to generate useful amounts of data.

A magical sunset in the bush next to the highway to Umbakumba.                                              Ami measuring one of our little darlings. 

I was on Groote Eylandt for 5 weeks helping Ami with data collection for her PhD project. As well as stunning landscapes and amazing native animals, Groote Eylandt is also home to a large manganese mine. All animals need some amount of manganese to function, but like any heavy metal it can be toxic in high concentrations. For her PhD, Ami is looking at how quolls from different parts of the island (that have been exposed to different amounts of manganese) perform in motor control and cognitive function tests. We are lucky enough to have access to laboratory facilities at the Anindilyakwa Land and Sea Ranger Station, where we get to work with the Rangers to figure out how to do our research in a way that is compatible with indigenous culture.

We went out every night and set 30-60 traps in one of our three trapping areas various distances from the manganese mine, which we then checked first thing the next morning. If we were lucky, we’d see white spots and hear some angry growling – otherwise it was rather likely that we’d caught one of the other marsupials that populate the area. We then transported our precious bundles back to the lab at the Anindilyakwa Ranger Station where we sexed them, weighed them, took various morphological measures and a hair sample (to get their internal manganese concentration from) and pit- and ear-tagged them.

Alfred, a feisty (and adorable) little male. 

Lastly, we’d gather information on their level of motor control. I won’t give away too many details, but we basically assessed their performance at various speeds and analysed how many mistakes they made depending on the difficulty of the task and the speed at which they performed it. We would expect that as speed and/or “difficulty” of the task increases, the quolls will make more mistakes. The reasons for this are very intuitive and you will probably have observed them in your own life; as you do things faster you have less control over your movements and are more likely to make an error. Similarly, if a task is difficult, you’re more likely to make a mistake than if it’s relatively easy. What Ami wants to know is whether the manganese concentration the quoll has been exposed to enhances this effect – i.e., whether high manganese concentrations affect motor control.

Back to the bush you go.                                                                                                                              Having a sniff out of the corner of his bag. 

Ami also wants to look at whether manganese concentration affects cognitive function in the quolls – but that’s for her to write about! She’ll continue to run these experiments for the next two years, and hopefully get some excellent results. I was very lucky to be involved in helping out with this project, as many of the techniques she used will be helpful in my own PhD.

Although quolls were the main attraction for us, Groote Eylandt has plenty of other amazing qualities that made my trip there one of the most memorable ventures into the field that I’ve ever had. We are extremely privileged to be able to conduct research there, and I learned more about indigenous culture than I ever thought I would. I also saw loads of awesome animals and plants, and got to spend a lot of time in the field – which is definitely one of the best ways to spend it.

A Mertens' Water Monitor (Varanus mertensi) chilling by Milyerrngmurramaja (the "Naked Pools"). These guys are also threatened by ingestion of the cane toads. A Striated Pardalote (Pardalotus striatus) that was nesting next to the Anindilyakwa Ranger Station.

A Burton's Legless Lizard (Lialis burtonis) we found while we were setting traps near Alyangula. A Helmeted Friarbird (Philemon buceroides) next to the highway to Umbakumba.

I’d like to say a huge thank-you to my lab for this opportunity, but most especially to Ami, Jaime and Gwen for teaching me so many new skills and being the best bush-buddies ever. I’m looking forward to future adventures with the Wilson Performance Lab as I start my PhD on another kind of carnivorous marsupial… the Yellow-footed Antechinus (Antechinus flavipes)!

Sunset on the beach at Ayangkwa ("Tasman Point"). 

All images by Rebecca Wheatley unless otherwise credited.

The Grand Slam: How Hard Should You Hit?

Squirrels know what’s going down (or do they)? Image source: Wikimedia commons.

The trade-off between performance and accuracy is a problem faced by a lot of different animals in a variety of situations. For example, consider a squirrel running along a bare branch to get from one tree to another; the faster it runs, the less time it spends exposed to predators. However, as the squirrel runs faster, it also increases its chances of mis-stepping and falling to its potential doom. 

So, to get the best of both worlds, the squirrel needs to optimise its running speed depending on its chance of slipping (the width of the branch) and the cost of falling off (the height from the ground).

These sort of performance/accuracy trade-offs are also commonplace in the human world. How fast should you smash out a text message to your supervisor asking him (politely) to email back your latest draft before the number of typos makes the whole thing unintelligible?  In particular, these trade-offs are of a great deal of interest in elite sports. An awesome example of a sport where this trade-off is of utmost importance is in singles tennis.

Serving hard: Heather Watson, Roger Federer and David Ferrer. Image source: Wikimedia commons.

In tennis, it’s pretty well accepted that if you serve really hard, it’s more difficult for your opponent to return the ball. But the harder you serve, the more likely it is that you’ll miss the service area and fault. So, players will usually belt it out on their first serve, but if they miss the first serve they’ll hedge their bets and serve softer the second time round to make sure they don’t double fault.

A/Prof Robbie Wilson, Dr Chris Brown and I have been testing this idea about performance trade-offs and optimal strategies using data from the men’s singles in the 2013 Australian Open. We’ve found this observation to be generally true: the probability of winning the point increases as the serve speed approaches its maximum, but the probability of faulting increases as well (for most players – some players are really consistent at getting it in regardless of how fast they serve). This was reflected in the frequency of high serve speeds in the first and second serves.

Jérémy Chardy, Andy Murray and Janko Tipsarevic. Image source: Wikimedia commons.

We’ve also constructed an optimality model which predicts the optimal serve speed taking into account the probability of faulting and the cost of a fault. An optimality model is, in essence, a mathematical model where you input the risks and rewards of a specific situation for a given individual, and it will tell you the optimal response for that individual if it wants to both minimise the risks and maximise the rewards. 

Optimality modelling is useful because it allows us to calculate the optimal response of specific individuals to any situation. We are looking at whether their opponent’s world ranking (ability to return a fast serve) and the point they’re going for or defending against (normal, game, set or match) affects their serve speed in relation to their optimum, but more on those results later.

Rafael Nadal, Caroline Wozniacki and Jérémy Chardy. Image source: Wikimedia commons.

We hope that our research can teach us more about how animals optimise their behaviour and physical efforts to improve their chances of successfully performing a given task. Depending on what we find, we might even be able to offer specific recommendations to tennis players wanting to improve their service game – who knows what the future might hold!

Andrew Hunter, a PhD student in our lab, is looking at performance/accuracy trade-offs in soccer. Will the results be similar between an individual and a team sport? We don’t know yet, but it will be interesting to find out.

Novak Djokovic, Agnieszka Radwańska and Venus Williams. Image source: Wikimedia commons.

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