Think:Health cultivates and articulates the best in health research and news.
The following episode, which aired on Sunday 16 August 2015, features:
- how mental fatugure affects performance in team sports (01:18); and
-
new research into the best methods to avoid ectopic pregnancy from IVF (17:40);
Academic guests:
- Mitchell Smith - PhD student
-
Associate Professor Alex Wang - Director, Research Studies at the UTS Faculty of Health
Host/s:
- Ellen Leabeater, 2ser
Listen online 107.3 2ser (audio length 30 mins)
START OF TRANSCRIPT
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Male: This is Think:Health on 2SER 107.3
Ellen Leabeater: Hello and welcome to Think:Health, where we cultivate and articulate the best in new health research. I’m Ellen Leabeater, and you’re tuned in 2SER 107.3. Today on the show: we look at how mental fatigue affects performance in team sports, and;
Alex Wong: We don’t know clearly whether it’s the treatment itself, related to the high risk of ectopic pregnancy, because women coming to this area of treatment, they already have the risk for ectopic pregnancy.
Ellen Leabeater: New research into the best methods to avoid ectopic pregnancy from IVF.
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Ellen Leabeater: It’s the last five minutes of a nail-biting game. You are trying your hardest to make sure your defender doesn’t get the ball, but despite your best efforts, you’re struggling to keep up. Well, it could be because of fatigue, and not just physical fatigue, but mental fatigue. Basically, if your brain is tired – from the game itself or maybe from a long day of work prior to the match – you’re not going to perform at your optimum. Mitchell Smith is a PhD student in the Faculty of Health at the University of Technology, Sydney. He has spent extensive time testing athletes to their mental limits to find out what impact fatigue has on performance.
Mitchell Smith: So, there has been a lot of studies that look into the effects of fatigue on subsequent skilled performances in things like driving, showing that there’s a huge negative impact there, but until the last six or seven years, there hasn’t been much research into the effects of fatigue on physical performance.
Ellen Leabeater: So, we’re talking about sport?
Mitchell Smith: Yeah, that’s right. So what we now know is that mental fatigue is really bad for endurance activity, so light intensity exercise that lasts about thirty seconds or longer, but high intensity exercise – the short duration stuff – isn’t necessarily effected by mental fatigue.
Ellen Leabeater: I guess the example that most people would know about is the Sally Robbins example –
Mitchell Smith: Sure -
Ellen Leabeater: - In the Olympics a couple of years ago where she just put her oars down and gave up. Is that an example of mental fatigue?
Mitchell Smith: Yeah, look, there would be research that would say it is. It was certainly a sad day in Australian sport. There’s certainly potential there for that to be a mental process happening. We obviously didn’t measure anything during that race, but physically there’s a chance she could have been able to continue, but she felt like she couldn’t give anymore, and it was kind of her mental capacity that she’d reached, so she slowed down or stopped because of that.
Ellen Leabeater: There are quite a few theories on how mental fatigue actually impacts on performance. One in particular you’ve looked at is the psychobiological model. Now, can you explain what this is?
Mitchell Smith: Yeah, so, basically it’s a model that was proposed by Professor Sam Markora from the University of Kent to explain why we stop or slow down during endurance exercise. Traditionally, the reason we slow down was attributed to physiological reasons like not enough oxygen to the heart and the muscles – a build up of lactic acid in layman’s terms…
Ellen Leabeater: So basically, physically, your body couldn’t push itself any further.
Mitchell Smith: Exactly, you’ve reached a kind of physical limit where your body can’t provide anymore of the required force or power output. And so, that was the traditional view. But more recently in the last ten to fifteen years there’s been more a push towards the influence of the brain, including psychological factors. And so, for the psychobiological model, the most important factors are “motivation” and this term we use called “perception of effort”, which basically means the exertion level that the participant or the athlete feels at that particular time. So, to put it simply, the psychobiological model says you stop or you slow down for one of two reasons: the first one is you’ve reached your maximal “perception of effort”, so you don’t feel like you can give any more; or the second one is your motivation isn’t high enough, so you give your maximal effort up to the level of motivation you have. So, maybe you’re motivated to give only 85%, and then your maximal “perception of effort” in that case would be lower, because your motivation isn’t high enough.
Ellen Leabeater: So how is mental fatigue different from physical fatigue?
Mitchell Smith: I think at a very basic level, mental fatigue results from long periods of mental activity and physical fatigue results from long periods of physical activity. So, mental fatigue is characterised by tiredness and a lack of energy, but physical fatigue is a reduced ability to produce the effort that is required. But when it comes to exercise, they’re really quite linked. So, I’ll give you an example of a study done about five years ago, where they had ten rugby players, and they cycled as fast as they could on an exercise bike – as fast as they could, as hard as they could for five seconds – and they measured their maximal power output for those five seconds, and they reached about 1000 watts, which is a pretty good effort. Then they cycled straight after that for as long as they possibly could at 250 watts, so at a much lower intensity, and on average they lasted about ten minutes. And then straight after, they were asked to give another maximal effort. So if there was just a physical reason for fatigue, then you’d expect that when they give their maximal after this time-to-exhaustion period, they wouldn’t be able to reach any higher than 250 watts, because they’d just pulled out at that level. But what they did reach was about 750 watts, so that’s three times what they needed to reach to continue. So clearly in this set, in this situation, there’s a physical fatigue happening because they reduce from 1000 watts to 750 watts, but that 750 watts was three times what was required to continue, so there’s definitely a decision there to stop exercising rather than continue at the low place. So a complex interaction happens during exercise. So even though mental and physical fatigue are quite different, they work together to, I guess, drag down performance.
Ellen Leabeater: And your most recent study looked at ten males who play team sports to see what their running performance was like after being fatigued. How did you mirror what would happen out on the field after, say, playing an hour game and then having to play in injury time when it’s really equal and you really have to give your all.
Mitchell Smith: Yeah, I think the difficult thing about my kind of research is that there are no coaches that are crazy enough to let us fatigue their players before they actually play a match, so what we have to do is actually take elements of a match and study them independently of the match. And so we fatigue people before running for example, and that’s what we did in this case. And so, we looked at studies called time-motion analysis studies - they use GPS tracking using matches – and we looked at all that data from various sports, so the rugby codes, AFL, soccer and field hockey. We put those together and we created this forty-five minute running protocol that was designed to simulate the demands of a match, or half a match at least (when it comes to soccer – 45 minutes). And we performed that on what we call a non-motorised treadmill, which is just like a normal treadmill, but instead of running to keep up with the speed of the belt, you run and that moves the belt, and we can then measure the speed, so it’s a freely paced exercise just like in a match. They stand there and a voice tells them over the speakers to run or to sprint or to slow down, and that matches the intensities of the game. There have been studies that show that there’s quite a good correlation between an actual match and that kind of simulation.
Ellen Leabeater: That was after putting them through a certain test though wasn’t it?
Mitchell Smith: Yeah, exactly. So, we had two conditions. In one of them they just watched documentaries and we used that as a control condition. But in the other condition, the mental fatigue condition, I’d guess you would say it’s quite unpleasant, so, thank you to my participants if you’re listening. It’s not fun to be a part of this research I don’t think, so they’ve done very well to complete. As I mentioned before, mental fatigue results from long periods of mentally demanding activity. So what we did, is we sat them down in front of a computer for ninety minutes, and they performed a task called the AX continuous performance task. Basically letters show up on the screen, and based on the string of letters, you select one of two buttons, and that’s it for ninety minutes. It’s a very boring task that leads to mental fatigue, and we then test the effects of that on their performance afterwards.
Ellen Leabeater: So what was the difference between the two groups?
Mitchell Smith: So what we saw was a reduced performance after mental fatigue – they decided or chose to run at a lower intensity after the mental fatigue activity than after the documentary. But more specifically, it was at low intensities that they reduced their velocity, but at high intensities they were able to maintain the same velocities as the control condition.
Ellen Leabeater: So they could sprint but they couldn’t necessarily run for a long period of time?
Mitchell Smith: Yeah, exactly right. So their general pacing profile reduced in velocity, but their sprints remained at the same kind of level.
Ellen Leabeater: So what does this mean for practical applications?
Mitchell Smith: So, I think there are a few ways to look at it. In a match, the high-intensity efforts are probably the most important efforts, whether you’re running for a line break or you’re kind of trying to get open or catch up with an attacker who is open – so these are really important efforts in a match. And so, chances are, even if you are mentally fatigued in a match, you will still perform in these situations because the high-intensity efforts aren’t necessarily effected by fatigue. But it’s the stuff in between, when you’re walking or jogging, where you’re most likely to be effected by fatigue. And what that could mean, is that you’re not in the right positions to start with to make those high-intensity efforts. So whilst the high-intensity effort itself is not necessarily effected, you might not be in a position to make that high-intensity effort.
Ellen Leabeater: So, you’re starting off on the back foot.
Mitchell Smith: Exactly right, yeah.
Ellen Leabeater: Is this mental fatigue that you induced – is it similar to what we’d see in a match?
Mitchell Smith: It’s a really good question. I think you often hear coaches and players attributing their poor performances to mental fatigue, even more so than physical fatigue these days. But there have actually been no studies done that investigate mental fatigue during a match, and there’s definitely an area we have to look at in the future. I would say, there’s probably a little bit of a difference between the mental fatigue we induced and the mental fatigue induced in a match, but we can’t really conclusively say anything about it at this stage. Obviously a match is mentally fatiguing. Obviously if you look at the mental demands of a match – having to make quick, accurate decisions over and over again in a constantly changing environment over a long period of time, it’s quite mentally demanding. And then if you put in the crowd and the pressure situation and those kinds of things, it can really add to those mental demands. So the chances are it is quite mentally fatiguing, but the research hasn’t got there yet. We’re still in the early stages. We’ve just looked at the acute effects of fatigue, and now we’re starting to become more practical with our approach and asking how fatigue actually affects match performance.
Ellen Leabeater: On performance as well – part of that in team sport is skills. So what effect does mental fatigue have on skills?
Mitchell Smith: Yeah, so there’s definitely a lot more to a match than just running. A lot of things like skill and decision-making can contribute to match outcome and are often more likely to contribute to the match outcome itself. So we did a study last year actually in Belgium where we looked at the effects of fatigue on soccer passing and shooting performance. And what we saw was that fatigue does have a negative impact on skills, in particular with passing. We saw that they were able to make a series of passes in the same amount of time when they were fatigued compared to a control condition, but there passes were much less accurate. So there was kind of a speed-accuracy trade-off potentially happening here, where they tried to keep the same pace of movement, but that results in a less accurate pass, and in a match, we know that sure passes are really important for performance. They’re often what lead to goals in a match, and we see that there’s a reduction in short passing ability towards the end of a match, so there’s a chance that even in a match, it is mental fatigue that can lead to a reduction to performance, probably in addition with physical fatigue.
Ellen Leabeater: Basically what you’re saying is, when you have to make all these quick decisions, it’s a lot more difficult when you’re fatigued.
Mitchell Smith: Yeah, so that was another study we did. Same design: we fatigued them in one condition and we had a control condition in the other, then we put them in front of a big screen that projected out soccer simulated plays, and they had to make decisions based on the information they had in front of them. And we looked at their eye tracking and we looked at their decision-making accuracy, we looked at their reaction time. We haven’t finished analysing all the data yet, so I can’t tell you about the eye tracking, which is maybe the most exciting part, but what I can tell you is that they made worse decisions and they made slower decisions when they were mentally fatigued. And so we’ve got kind of this multi-faceted effect happening in team sports, where if you’re mentally fatigued it affects your physical performance, but it also affects your decision-making, so you might make the wrong decision, and then even if you do make the right decision, chances are you’re going to perform that skill poorly. So, it’s obviously a really bad idea to be mentally fatigued before a match.
Ellen Leabeater: One of your suggestions is to taper mentally, like you would taper physically, so, tapering is done before an event, two weeks or one week before to make sure you don’t injure yourself or so you’re not physically exhausted by the time the event comes around. Your suggestion is to do that mentally as well, so what would that involve?
Mitchell Smith: Yeah, so the idea with physical tapering, like you said, is to put yourself in a position where you can perform optimally in your competition. So anywhere from a few days to a few weeks, they reduce their training load, so that when their competition comes around, they’re able to produce their maximal potential effort. We think potentially there could be some usefulness in doing the same thing with mental activity, so reducing the amount of difficult mental work you do in the lead up to competition. And that could potentially put you in the perfect mental space to perform as well as the perfect physical space. Like I said earlier, I think we’re still in the very early days of this mental fatigue in sports research, so it’s all speculation at this stage I think. If someone was to incorporate brain endurance training, you would certainly not want them doing that right up until the competition, but whether athletes are doing other mentally fatiguing tasks in the lead up to a competition, I’m not sure if that is much of a big deal at this stage – that it’s enough of a mental stimulus to lead to negative performance. But again, it’s very early days. All we know at this stage is that mental fatigue before competition would be a bad idea.
Ellen Leabeater: Mitchell Smith from the University of Technology, Sydney ending that report. Here on 2SER, you’re listening to Think:Health. Up next we find out whether fresh or frozen is best in preventing ectopic pregnancies in IVF treatment.
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Ellen Leabeater: Welcome back to Think:Health here on 2SER, I’m Ellen Leabeater. Approximately one to two percent of pregnancies in Australia are ectopic, which means that the embryo attaches outside of the uterus, for example in fallopian tubes. But this rate is much higher in pregnancies that result from assisted reproductive technology such as IVF, with the rate being as high as 10%. A range of reasons, many of which are still yet to be discovered, can cause ectopic pregnancy following IVF, however one contributing factor may be the type of IVF treatment women undergo. New research has looked at the best IVF treatment to reduce the risk of ectopic pregnancy. Alex Wong is one of the authors of the study. Alex is an Associate Professor of Perinatal Epidemiology and he is also a statistician in the Faculty of Health at the University of Technology, Sydney. Alex and his team have found that single frozen embryos are less likely to result in ectopic pregnancies than fresh double embryo transplants.
Alex Wong: Basically, ectopic pregnancy is a complication of pregnancy which is the embryo is not implanted into the uterus but the outside of the uterus.
Ellen Leabeater: And is that something that happens when it’s being implanted or does the embryo move?
Alex Wong: Basically the embryo moves, yeah. It can happen in the fallopian tubes- the majority are in the fallopian tubes – and it can be also in the cervix or ovaries.
Ellen Leabeater: So, in IVF, is it being implanted in the wrong place?
Alex Wong: No, actually it’s not. All embryos are transferred into the uterus. Depending on the uterus environment, the embryo may move.
Ellen Leabeater: What is the rate of ectopic pregnancy for assisted reproduction – so things like IVF – compared to a normal pregnancy.
Alex Wong: Yes, so in the general population with natural conception, the ectopic pregnancy rate is about one in 50-80 pregnancies. Or to use another measurement, it’s 1-2% of live births.
Ellen Leabeater: So, it’s pretty low.
Alex Wong: Yeah, less than 2% for live births. Whilst for assisted pregnancies, say IVF pregnancies, it’s between 2-10%. It is quite high following IVF treatment.
Ellen Leabeater: So, what causes ectopic pregnancy?
Alex Wong: We see ectopic pregnancy because the embryo has not become implanted into the uterus. That’s the reason. There are some risk factors for ectopic factors, including chlamydia infection.
Ellen Leabeater: Chlamydia?
Alex Wong: Yes. And tube factor infertility, ulcers and also IVF treatment.
Ellen Leabeater: So, sorry, that was with natural pregnancies?
Alex Wong: Yes.
Ellen Leabeater: So why does the rate of ectopic pregnancy rise with IVF?
Alex Wong: So, as we see, the risk factors include tubal disease and (unclear) ulcers, where that’s all the reason why people come for the IVF treatment. So women who come for the treatment, they already have the risk of ectopic pregnancy, because they can’t get pregnant by themselves, they access this area of treatment.
Ellen Leabeater: So, what are the outcomes for parent and child or mother and child?
Alex Wong: Yes, well in terms of the child, in the majority of ectopic pregnancies, the child won’t survive, so the outcomes are not good for the child. For the mother, more than 50% have vaginal bleeding or they have abdominal pain – the pain can be very sharp – or they have both. And it can be life threatening because of severe bleeding. Ectopic pregnancy is the most common cause of death in the first trimester of pregnancy. It accounts for over 10%.
Ellen Leabeater: So with these women who are at high-risk of ectopic treatment anyway, is there anything in the IVF treatment that clinicians are doing to reduce that risk?
Alex Wong: That’s part of the study that we’ve done. But we don’t know if it’s the treatment itself related to the high-risk of ectopic pregnancy clearly, because the women that come for IVF treatment already have the risk of ectopic pregnancy. We did find in the study that different treatments may reduce the risk of ectopic pregnancy.
Ellen Leabeater: The study that you did was looking at the different ways we implant embryos, so whether we have fresh or frozen, whether we have single or multiple. In your study, which combination had the best success rate?
Alex Wong: Yeah, so we looked at single embryo or double embryo at cleavage stage and at blastocyst stage – in other words at the Day 3 and Day 5 stages – so whether it’s fresh or frozen. Day 3 stage is cleavage stage – the embryo is still splitting. So then we check all these different combinations, and actually we found a single frozen Day 5 embryo has the lowest risk of ectopic pregnancies. Basically we have two explanations for the difference between fresh and frozen. We found the frozen embryo has lower risk of ectopic pregnancy. The reason is because in a fresh treatment, the uterus environment is negatively impacted by the hormone stimulation. Whereas in a frozen embryo transplant, the uterus environment is like a natural conception.
Ellen Leabeater: See I find that very… In my mind, a fresh embryo would be more likely to work than a frozen one.
Alex Wong: Yeah. How you get fresh embryos… because you have to stimulate the ovary to get more eggs, the hormone stimulation has a negative impact on the uterus environment, and also, the hormone stimulation may increase the contractivity of the uterus. High contractivity may move the embryo from the uterus into the tubes.
Ellen Leabeater: So because your body is going through something which is so unnatural – i.e. this heightened stimulation – it’s not exactly the best environment for –
Alex Wong: For the uterus it’s not the best environment.
Ellen Leabeater: Whereas with the frozen embryo, your ovaries have been stimulated, you’ve taken the ova out, your body is allowed to recover, and then you put the embryo in.
Alex Wong: Yes.
Ellen Leabeater: So to reduce the risk of ectopic pregnancy, we need a single embryo transfer that’s frozen.
Alex Wong: Yes, single frozen embryo transfer at Day 5.
Ellen Leabeater: So why are the Day 5 embryos better than the Day 3 ones?
Alex Wong: There are a couple of reasons. So for fresh embryo transfer, Day 3, maybe the uterus is not ready for the transfer yet because of the hormone stimulation. Whereas at Day 5, the uterus is more ready for the embryo.
Ellen Leabeater: So those extra two days make a difference.
Alex Wong: Yes, but again, this only looked at the transfer cycle. What we want to look at is to look at a patient coming in, with, for example ten embryos. We want to look at when all the ten embryos have been transferred what is the outcome for live births.
Ellen Leabeater: Different clinics use different methods of implantation. Could this impact on the results at all?
Alex Wong: It’s hard to say from this study, because in most countries clinics may have slightly different ways of practicing, for example single embryo transfer or double embryo transfer, transferring fresh or frozen, or transferring on Day 3 or Day 5. This is because the patients are quite different. Each clinic has a different cohort of patients. We know the underlying infertility, for example tubal disease and mitosis increase risk of ectopic pregnancy. So if the cohort of patients is different from clinic to clinic, that means that the risk for ectopic pregnancy is different. Then that’s why we can’t, based on this study, say whether clinical practice has an impact on ectopic pregnancy.
Ellen Leabeater: Alex Wong from the University of Technology, Sydney ending that report.
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Ellen Leabeater: And if you’d like to find out more about that story or listen to any of our past programs, head to our website at 2ser.com/thinkhealth. This show is produced with the support of the University of Technology, Sydney, Faculty of Health.
Please remember that you should not consider the content of this show medical advice and you should consult your physician if you have any concerns.
I’m Ellen Leabeater, this has been Think:Health. See you next week for more in health research and news.
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