Category: Sports Science

diet, nutrition, Sports Science, weight management

Good calories, bad calories and weight gain/loss

Time goes fast and I realized the blog has been abandoned for quite a while. I have been reading recently a little bit about weight loss, mainly to update my knowledge, and also for some personal interest, having suffered a broken rib and now trying to recover some shape!

My interest was initially on rapid weight loss. So I wend back to read some old papers on rapid weight loss and performance (e.g. Fogelholm et al., 1993 ) which showed for example that 6.0 +/- 0.6% of body weight was lost in 2.4 days by fluid and diet restriction and forced sweating, and when followed by a 5-h "loading" (food and drinks ad libitum) there was no change in performance with a gradual weight loss programme. However while in experienced athletes such approach might still not produce visible and measurable reductions in physical performance, it seems clear that psychologically they are highly likely to suffer (see Hall and Lane, 2001) as well as having some impairment in cognitive function (see Choma et al., 1998).

However, while looking for some literature on dietary aspects of weight loss I came across some interesting information.

First, two interesting books I just ordered: Good Calories-Bad calories  and Why we get fat from Gary Taubes which quite rightly points the finger to carbohydrates and their abundant use as the main cause of obesity. I will read the books and then write a review, as while I am keen to read his summary of the carbohydrate issue, I am not so convinced about his views of the role of exercise on weight management. What pointed me in that direction was a great letter written by Professor Tim Noakes on the British Medical Journal’s blog. As usual Tim has written some interesting comments. Have a look at it and make your mind up!

The internet is always full of surprises and while looking for information I have been impressed by the project of a personal trainer who decided to gain weight before losing it again to learn how it feels to be overweight and then to show how his methods work in getting himself back in shape. He started in May his weight gain plan and is due to start the reverse process in November. If you are curious about it, go read his blog here.

Coaching, Sports Science, Technology

Muscle oxygenation in-vivo

Our paper on the possibility of using Near Infrared Spectroscopy (NIRS) to measure muscle oxygenation in-vivo in elite athletes has now been published ahead of print by Medicine and Science in Sports and Exercise.

This study is the first of a series of studies constituting the PhD studentship funded by the BOA to study the possibility of using NIRS in the field as a tool to understand performance demands and adaptations to training as well as developing innovative portable integrated brain and muscle devices. The research programme is a collaboration between ourselves, the University of Essex with Professor Chris Cooper and Professor Clare Elwell at University College London.

The main author of this work is Catherine Hesford and you can find more info and contact details here.

More work will be published in the next months and I will write more about this fascinating technique soon on this blog.

The abstracts is available below.

Med Sci Sports Exerc. 2011 Sep 3. [Epub ahead of print]

Asymmetry of Quadriceps Muscle Oxygenation During Elite Short-Track Speed Skating.

Hesford CM, Laing S, Cardinale M, Cooper CE.

Source

1 Department of Biological Sciences, University of Essex, UK; 2 British Olympic Medical Institute, University College London, UK; 3 University of Aberdeen, School of Medical Sciences, Aberdeen, Scotland (UK), 4 School of Sport, Health and Exercise Sciences, Bangor University, UK.

Abstract
PURPOSE:

It has been suggested that due to the low sitting position in short track speed skating, muscle blood flow is restricted, leading to decreases in tissue oxygenation. Therefore wearable wireless-enabled Near Infrared Spectroscopy (NIRS) technology was used to monitor changes in quadriceps muscle blood volume and oxygenation during 500m race simulation in short-track speed skaters.

METHODS:

6 elite skaters, all of Olympic standard (age = 23 ± 1.8 years, height 1.8 ± 0.1m, mass = 80.1 ± 5.7kg, mid-thigh skin fold thickness = 6.8 ± 2.2mm) were studied. Subjects completed a 500m race simulation time trial (TT). Whole body oxygen consumption was simultaneously measured with muscle oxygenation in right and left vastus lateralis as measured by NIRS.

RESULTS:

Mean time for race completion was 44.8 ± 0.4 s. VO peaked 20 s into the race. In contrast, muscle tissue oxygen saturation (TSI %) decreased, and plateaued after 8s. Linear regression analysis showed that right leg TSI% remained constant throughout the rest of the TT (slope value = 0.01), whereas left leg TSI% increased steadily (slope value = 0.16), leading to a significant asymmetry (p<0.05) in the final lap. Total muscle blood volume decreased equally in both legs at the start of the simulation. However, during the course of subsequent laps there was a strong asymmetry during cornering; when skaters travelled solely on the right leg there was a decrease in its muscle blood volume whereas an increase was seen in the left leg.

CONCLUSION:

NIRS was shown to be a viable tool for wireless monitoring of muscle oxygenation. The asymmetry in muscle desaturation observed on the two legs in short-track speed skating has implications for training and performance.

references, software, Sports Science

Free reference manager and PDF organiser

I have not had much time to write on the Blog recently. London Olympics are approaching fast and there are too many things to do and too little time!

Anyway, I will write a short article to praise a recent addition to my software tools. Of course this is another freeware. All of us continuously struggle to organise all the PDFs of the scientific articles we read and also make sure we can site while we write articles. Commercial software packages are of course available, however I came across a great freeware solution: Mendeley. If you want to look at a short video to explain how it works, have a look at this video:

http://vimeo.com/user5499963/what-is-mendeley

I have downloaded and used the software for few days now, and it has been very easy to create specific folders and import PDF files arranging my references by topics.

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The folder syncs with server space, so it is possible to keep all the documents and libraries if your computer crashes or if you lose it, as well as push the content to other devices.

It is also possible to annotate, highlight and share comments with others.

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Also, it is possible to create shared libraries so everyone can add and share comments as well as share the PDF contents. Finally, it is possible to create an online group to share knowledge on a particular area.

A great tool for anyone to use. The free version provides 500MB of space free and 500MB to be shared as well as the possibility to have 5 private groups ad 10 users. More space and more options are available for reasonable fees.

Curious? Download the software and find out more about Mendeley here:

Mendeley reference manager logo