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Items filtered by date: March 2014
Monday, 24 March 2014 00:00

Heart rate variability - my PhD so far

Last Friday I uploaded a factsheet on heart rate variability. It's a little remiss of me not to have done so sooner seeing as HRV is the topic I am researching for my PhD. The factsheet was written by my supervisor Jeanne, and while everything contained within it remains true, there has been a lot of research published in the five years or so since it was written so here is my take on the latest research in the sporting applications of HRV and the questions I am trying to answer in my own research.

HRV_analysis_stepsPerhaps the easiest place to start is by stealing an image from our HRV factsheet to explain the process behind the application of heart rate variability. From a coaching perspective, the interesting part is the interpretation stage - "What does HRV tell me that can improve performance?" I'd like to say I've found the answer to that question but in truth, I'm a little way from making such a bold claim! The recording, editing and processing stages are perhaps not the most sexy of conversation topics but I'm a maths geek at heart and I have to say I'm beginning to relish the chance to use some of the knowledge from my undergraduate maths degree. It's often said that if you truly understand something you should be able to explain it in a few sentences so this is the story of my PhD so far... (I will assume you've read the heart rate variability factsheet, so if anything doesn't make sense I suggest you start there)

Recording

Data collection on the face of it is quite straight forward, the technology is now available to measure RR intervals using heart rate monitors (Polar and Suunto make popular models). As with everything these days you can also get an app for it, with ithlete probably being the most well known. Contrary to the info in the factsheet, there have also now been quite a few studies comparing HRM data with ECG recordings with quite frankly mixed results. Having collected some comparison data myself, there aren't significant differences, but the HRV parameters you calculate aren't really the same. In short, I decided to focus on ECG recordings for the first part of the PhD in the interests of scientific rigour. If HRV is fundamentally based on the time between successive R peaks in an ECG recording it's reassuring to see that ECG trace on a screen and be able to check that everything's as it should be. There is also the issue of how long, when and in what position to make the ECG recording. More on that later...

Editing

Not much to add here other than stress the importance of having a good data signal. Within an ECG or HRM monitor recording there are often non-physiological data, you may have seen it on your own heart rate data where the signal drops out or you get an abnormally high HR for a few seconds. This makes a huge difference to the HRV parameters you calculate from the recording. When I sent the heart rate monitors out into the field for athletes to record data at home, I was having to remove >5% of the data points in some cases. Unacceptable for scientific research and it certainly reduces the confidence as a coach in using that data to make a call on training. Ultimately, for HRV to be of practical use on a daily basis the use of HRM technology is of fundamental importance, but I want to get a handle on the acceptable limits in a controlled lab setting before I get my hands dirty in the real world.

My study

So with these thoughts in mind, my first major study has involved answering a few questions on the methodology and reliabilty of HRV data. I'm collecting data using a 3-lead ECG and am following a commonly used protocol in the existing research of collecting 10 minutes of data supine (lying down) followed by 10 minutes standing. One difference is that rather than ask subjects to stand themselves following the supine period, I've actually got use of a tilt table at the University that is essentially a motorised bed that tilts from horizontal to vertical in ~30s. I'll try and get a video next time I'm in because it's not a particularly common piece of kit. The big advantage with this is that it standardises the transition from lying to standing. My aims for this study are as follows:

  1. Length of recording for analysis: although I've collected data for 10 minutes in each position, I have the choice to only analyse part of that recording. For example, the ithlete HRV app uses a recording of 1 minute but the main references in the literature suggests 3-5 minutes as optimum for short duration recordings. So my question is does it matter or can I use any length of recording from 1-7 minutes?
  2. Test-retest: reliability is incredibly important for any measure that you hope to have applications. If I take two recordings on the same person without changing anything do I get the same result? For example, if I measure HRV in an athlete and then repeat the measurement 10 minutes later with them resting throughout and the the two values are very different it has drastic implications for the usefulness of that measure.
  3. Averaging: rather than using one recording, if I use an average of a number of sections within the 10 minute recording do I improve the reliability?
  4. Orthostatic stress: this is where I first begin to look at the physiology rather than just the mathematics... how useful is that transition from lying to standing? It's been suggested that the nervous system response to a stress (such as standing up) is potentially a more useful measure than a resting measure in one 'state'. I spoke with Thomas Prehn (former US national road champ) on the India training camp last year and I was fascinated to hear that in his racing days he used to take a resting heart rate lying in bed and then on standing and could tell from the difference if he was able to train at a decent level that day. So it's certainly not a new concept, but I'm hoping with the control of the tilt table I might come up with further insight. Maybe a little modelling of the speed with which the parasympathetic nervous system withdraws could be on the cards :-)

I've got a little more data to collect and a bucketload of statistics to play with but this is a vital step to ensure that protocol I settle on is robust enough to be of practical use. If so, I've got a few ideas for what's to follow but I'll save that for another time. Watch this space!

Published in Blog
Tuesday, 18 March 2014 00:00

Early season lessons

Last time I spoke about the nerves that can accompany the first races of the year. Just after I uploaded the blog, I was mortified to see that Helen had written a blog entitled "Early season failure..." on the same subject at this stage exactly 3 years ago... have I really become that unoriginal?! In any case after several months without competition (or maybe competing in a different sport or discipline), it's fair to say that many of those nerves come from an unfamiliarity with racing and a desire to match or beat our best performances from last year. It's always difficult because the freshest race in your memory is probably one that came at the back end of last year when you were battle hardened and were close to peak fitness after a summer of racing and training hard. My final word on the subject is a reminder to compare with a similar time point from last year, within the context of your current plan of course.

If we acknowledge that nerves will be there in the early part of the season, what can we do to minimise these feelings and mitigate the negative effect on performance? Here are some reminders of things that might help:

  • Suffering - it doesn't matter how hard you've trained through the off-season, that first race always flippin' hurts! Don't fool yourself into thinking any differently and you won't be disappointed. As the great man once said "It doesn't hurt any less, you just go faster"
  • Pacing - a few months away from competition and for most athletes any concept of pacing goes out of the window. I've lost count of the number of time trialists who upload their first race file to Training Peaks with the first minute of their TT at 500W+... you are not Tony Martin! Remember to pace according to your current level of fitness, not where you were at your peak last year and not where you want to be at your peak form later in the year.
  • Routine - take some time to remind yourself of how long it takes to prepare for racing ahead of the first few events. Another common observation is that a number of athletes have to cut their warm up short to make the startline on time. It's easy to forget how long it takes to sign on and visit the bathroom five times before the race and it's worse at this time of year when it may be the first time you've seen your friends/adversaries in a while. Write out a timeline if it helps and include a little buffer time for those unforeseen distractions.

These tips are not rocket science but on reviewing some more video footage from the PBscience archives, I found it amusing (and frustrating) to think that as a coach we need to have these same conversations with athletes each year. Make a kit list, pack your bag the night before, make sure you know where the HQ and startline are, be sure to leave in plenty of time,... I'm not one for making extra effort so I'll let you watch my (grainy) footage from the PBscience early season workshop in 2010.

logoECFsmIn other news, PBscience are glad to be supporting the Eastbourne Cycling Festival by offering a free training plan for entrants to the Sportive. The Sportive is sponsored by our good friends at the Tristore, so be sure to pay them a visit in the run up to the event. It's great to see the Festival establising itself on the Western Lawns and there's another action packed day in store on Sunday 1st June. I'm particularly looking forward to the Urban cyclocross and may stick an entry in for one of the criteriums. Take a look at the plan and feel free to share with anyone who might be interested. It's aimed at the Eastbourne event but should be useful to anyone after a bit of guidance for a UK sportive, or something like the London to Brighton.

Published in Blog
Monday, 10 March 2014 00:00

Early season nerves

The early part of the race season is a nervous one for every athlete and 2014 is proving no different. It doesn't matter how well the off-season has gone, there's always a great deal of expectation when March rolls around the pressure to perform suddenly appears. For many of the athletes I work with, we're into multiple seasons together and that places additional pressure on both athlete and coach. These first events are often ones that have been ridden several times before and so we're competing not only against the other athletes and our own targets but also the ghosts of seasons past.

There's also the challenge of continual progress. The great thing for me about working with athletes over a number of seasons is that it probably means we've got more right than wrong. I would hope they wouldn't be hanging around if I'd done a terrible job! We know what works, or at least what has worked in previous years, but I'm a big believer in if you do the same preparation you can expect the same results. Each year the challenge becomes to find something different to try, or at the very least refine our current practises in search of a breakthrough to the next level. I'm yet to have a perfect build up with an athlete so there's always room for improvement. From the start of my coaching career having Helen as a mentor soon removed the fear of training experimentation - I can't imagine there are many coaches who would perscribe 30s all-out Burgomeister sprints for an elite ironman triathlete in the run up to Kona! Anyhow, too often on blogs like this we focus on our successes and how awesome we are so today I thought I'd look at a few examples of things that have gone wrong lately.

I'll start with Dan because that's freshest in my mind having just looked over his race file from the weekend. We've had some success in previous years with some good race wins, notable scalps and that elusive first 30mph TT. After some time away from structured training and racing to welcome Jack into the world, and a change in shift patterns at work to something less amenable to consistent training, we're back trying to tick off some of those goals that didn't quite come off in previous years. With a lower total training time, I made the cardinal sin of pushing too hard too soon, form came good and then went off the boil again and this conincided with a string of illnesses and time off the bike. It's fair to say we're a little way off Dan's best and the opening race at the East Surrey Hardriders was not the glorious season opener it has been in previous years. Fortunately Dan's the sort of rider for whom form is never more than a few good weeks of training away so we're not panicking yet :-)

On the road racing front, Nic is in Taiwan for his first stage race of the year and one we were hopeful of a decent result in. These short stage races have become something of a forte over the last few years and we've deliberately accelerated his training over the winter in an effort to reach a good level earlier in the year. Our last discussion before Nic departed for China was regarding the small time gaps that normally decide this race and the need to be attentive at all times. Cue a first stage crash in the opening criterium and a loss of over 5 minutes. I guess we should be thankful though because the two guys who came down with Nic were forced to abandon from their injuries. Nic has recovered well and been involved in the action on the subsequent stages but the race is as much about finding his race legs as much as a result now. The crashes in the peleton continue to come thick and fast so the number one priority is to get home in one piece! No where is early season nervousness more evident than in a twitchy road race peloton.

In more positive news, Jill is another athlete with a number of seasons of working with first Helen and then myself. In the past, I've been guilty of allowing Jill to detrain too much over the winter months, first with a lack of sufficient intensity of training and secondly with a lack of volume when we looked to address the first mistake. This off-season has been a great one for Jill and she's managed to juggle building her own Performance and Lifestyle Coaching business (check out The Wholesome Peapod), alongside some exceptional strength and conditioning work in the gym with her traininer Paul and still managing to do the necessary work on the bike. The key factor with Jill is balancing these conflicting demands and she's done the best job yet of this. Jill's continuing to set lifetime PBs after many seasons of time trialling and I confident that will continue this year.

So what do you do when things don't go according to plan in the opening races of the season? I use it as an opportunity to review our plans, make an honest assessment of our mistakes and be sure to put right any wrongs. When I first started coaching I used to panic at the first sign of trouble but I guess I've seen enough early season troubles turn into susccessful seasons to have faith in staying the course. That's not to say we're becoming complacent!

Which kind of loosely links to my closing thought for this week, I spent an hour reviewing an old video from Helen entitled winning in cycling the other night ahead of an upload to the new PBscience YouTube channel. It's a great reminder at this time of year that success is as much about the process and your attitude as it is about the results. Cycling has been harmed more than most sports by a win at all costs attitude so it's useful reminder to focus on excellence in the process rather an all-consuming results focus. Part one is below and you can find part 2 and part 3 over on YouTube. The weather has been pretty kind lately but it's bound to take a turn for the worse again soon so use it to pass the time next time you're on the turbo trainer!

Published in Blog
Monday, 03 March 2014 00:00

PBscience athletes 2014

April_TTT

Following last week's update on the regeneration of the website, it's only fair that this week I focus on our athletes. Oli and I are fortunate to work with a great bunch of athletes and so here's a quick round up on what some of them have been up to and a few notes on what to look out for over the coming season. These are the guys and gals that I'm working with but I'll get Oli to add a few notes at some point too. In no particular order...

Our UK based time trialists are emerging from a wet and windy winter and the first few events are either in the bag or or soon will be. John started with a bang and took the win in the opening Eastbourne Rovers club event and Jill, Dan, Keith and Dave all have their first race in the next week or two. After an injury blighted 2013, Pete is in the wars again having undergone a knee operation but is well on the road to recovery and looking to regain the form that saw him take the National vets 24hr crown in 2012.

Nic_Vorarlberg_banner

April picked up where she left off last year and drove her Madison team mates to victory in the 4up team TT in Bermuda. I don't envy her team mates having to ride a TTT with her because she's in great form already, ahead of her main targets later in the year. On the other hand I do envy the shorts and short sleeved jerseys! Michael and Marc have both had a chance for some winter sun with a couple of early season training camps that will undoubtedly stand them in good stead later in the year.

On the subject of escaping to the sunshine, Bjorn has made the decision to up sticks and leave for an extended stay in India. I'm sure you'll join me in wishing him all the best as he looks to establish his bike fit business (Cycle Precision) on the sub-continent. Look out for a strong showing on the Banglore race circuit too!

On the continent, Nic is relishing the move to a new team and has settled in very well with Team Vorarlberg in Austria. His first two races are in the books, with a trip to the Tour of Taiwan looming large for the weekend. The numbers are looking good in training and so we're hopeful of a good showing. Nic was the subject of Helen's most read blog post 'The physiologist of a pro cyclist', so I'm planning an update in the coming weeks to show the development over the last few years.

Also new to the PBscience fold is Sam, with a very public project in partnership with the Tristore. The Tristore have always been great supporters of PBscience so it's great to be involved with Project Sam! Emma's progressing well on the way to the Cambridge Duathlon as a first target for the season and finally welcome on board to Chrisptoph and Mark who are both aiming towards the Haute Route Sportive later in the summer.

On the website front, since last week's blog I've uploaded a new video giving Helen's tips on recovery from training with the particular example of training twice in one day. I've also added a factsheet on training in zone 6, a bit of a love/hate area of an athlete's physiology. We love training there because of the big gains it can bring but hate training there because it bloody hurts! More to come this week...

 

 

Published in Blog