Category: Technology

biochemistry, science, Technology

>Nanosensing and biochemistry

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This is not really new…but it was new to me today when I found some articles on this innovative technology. I am talking about a nanosensor that could be injected into the skin, much like tattoo dye, to monitor an individual’s gluclose level. As the glucose level increases, the dye would fluoresce under an infrared light.

The researchers at Draper Laboratory, in Cambridge (MA), have already tested a sodium-sensing version of the device in mice, and are due to begin animal tests of the glucose-specific sensor.

The material consists of 120-nanometer polymer beads coated with a biocompatible material. A patent application has been filed. Within each bead is a fluorescent dye and specialized sensor molecules, designed to detect specific chemicals (so far the work has been done on sodium and glucose).

When injected into the skin, the sensor molecule pulls the target chemical into the polymer from the interstitial fluid. To compensate for the newly acquired positive charge of a sodium ion, a dye molecule releases a positive ion, making the molecule fluoresce. The level of fluorescence increases with the concentration of the chemical target.  The range of concentrations that the sensor can detect can apparently be varied, depending on whether it is important to measure precise concentrations or more broad variability.

The sodium sensor has shown early success in animals. The researchers have developed a glucose sensor that works via a similar mechanism. It has been shown to work in a solution but has not yet been tested in animals.

Still, the researchers have a long way to go before the sensor is ready for human testing. However, if it works and it is accessible, this could be a good way to make a good use of a tattoo 🙂

 

 

heart rate, monitoring, Sports Science, Technology, training

Monitoring training load: quo vadis? #2

After having presented a simple method to monitor training load without the need of expensive equipment, it is now the time to discuss other methods which involve the use of equipment.

The first and obvious one is monitoring training with the use of heart rate monitors. Thanks to the development of technology it is nowadays possible to measure in real time heart rate (HR) of numerous players on the field without the need for them to wear a watch or a recording device. Many companies in fact provide telemetry systems capable of storing and transmitting heart rate values recorded during training and/or competition. When I first started working in this field may years ago I remember the excitement of being able to measure HR during training and be able to download the files for analysis using the conventional heart rate bands and watches. The cost was prohibitive (there was no way I could afford 20 watches + HR bands!), it took ages to download the files with 1 interface connected to a serial port, and most of all, because athletes needed to wear a watch…we had to be creative about where to place it and also be prepared to sacrifice a few in some contact sports or due to falls.

Nowadays, it is very easy! The current systems can transmit information in real time, it is possible to measure many athletes at the same time and it is possible to store and analyse all data immediately after the end of each training session. Furthermore, due to the improved quality of the sensors used and the software and hardware developments, it is also possible to measure R-R intervals and analyse heart rate variability (HRV).

 

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Heart rate can be considered as a reliable indicator of the physiological load both for immediate training monitoring and for post-training analysis in almost every sport. However, considering the influence of psychological components like anxiety and stress on HR, it is feasible to suggest that an appropriate assessment of training intensity should also consider this limitation of HR monitoring.

Typical training plans of team sports are characterised by a combination of technical and tactical specific drills, small sided games, or general types of team drills. In the above situations, all members or small groups of the team perform similar tasks. The determination of training intensity and training stress is an extremely important parameter for training planning and for appropriate distribution of training load in elite athletes competing in team sports.

The following methods have been suggested to be effective in quantifying the training load:

The Training Impulse [TRIMP] method

Proposed by Bannister et al. (1975), characterised by the following equation:

TRIMP = training time (minutes) x average heart rate (bpm).

For example, 30 minutes at 145 bpm. TRIMP = 30 x 145 = 4350

This approach is very simple, however it does not distinguish between different levels of training. So it has been used mainly to determine general load in aerobic-endurance sessions.

TRIMP TRAINING ZONES METHOD

Developed by Foster et al (2001)  is based on assigning a coefficient of intensity to five HR zones expressed as a % of HRmax:

1. 50-60% HRmax

2. 60-70% HRmax

3. 70-80% HRmax

4. 80-90% HRmax

5. 90-100% HRmax

The zone number is used to quantify training intensity; TRIMP is calculated as the cumulative total of time spent in each training zone.

For example

  • 30 minutes at 140 bpm. Max HR = 185 bpm. %max HR = 140/185 x 100 = 76%. Therefore, training intensity = 3.

TRIMP = training volume (time) x training intensity (HR zone) = 30 x 3 = 90.

  • 25 minutes at 180 bpm. Max HR = 185 bpm. %max HR = 97%.

Training intensity = 5. TRIMP = 25 x 5 = 125

The zone TRIMP calculation method can distinguish between training levels while remaining mathematically simple, however this can only quantify aerobic training and it does not allow quantification of strength, speed, anaerobic and technical sessions.

TRIMP Zones + RPE

Combining the two methods allows the determination of training intensity not only from a cardiovascular standpoint, but also taking into account the perception of effort and can be extended to strength training to be able to collect a cumulative training load score.

EPOC (excess post-exercise oxygen consumption) Methods

EPOC is basically the excess oxygen consumed during recovery from exercise as compared to resting oxygen consumption. The EPOC prediction method has been developed to provide a physiology-based measure for training load assessment.

EPOC is predicted only on the basis of heart rate derived information. The variables used in the estimation are current intensity (%VO2max) and duration of exercise (time between two sampling points, Dt) and EPOC in the previous sampling point. The model is able to predict the amount of EPOC at any given moment. No post-exercise measurement is needed. The model can be mathematically described as follows:

EPOC (t) = f(EPOC(t-1), exercise_intensity(t), Dt) (Saalasti, 2003)

At low exercise intensity (<30-40%VO2max), EPOC does not accumulate significantly after the initial increase at the beginning of exercise. At higher exercise intensities (>50%VO2max), EPOC accumulates continuously. The slope of accumulation gets steeper with increasing intensity.

(The following figure is from Firstbeat Technologies Withepaper)image

The relationship between measured and HR derived EPOC has been shown to be significantly large suggesting this method as an alternative solution to determine training load with minimally invasive procedures such as wearing a chest band (Rusko et al., 2003).

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And by the same authors has been shown to be related to blood lactate.

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The EPOC approach has been nowadays introduced by various HR monitors manufacturers (www.suunto.com and www.firstbeattechnologies.com).

(Figure above from www.suunto.com)

Various manufacturers are now developing innovative approaches to describe training loads based on HR measurements (e.g. http://www.polar.fi/en/b2b_products/team_sports/software/polar_team2_software) and more will be available soon due to the ability for the current systems to record with high accuracy also R-R intervals and derive training stress information from Heart Rate Variability indices.

I will write more on these in the next posts on this interesting topic…this is it for now…stay tuned!

science, Scientific publication, Technology

Light and wound healing

I recently came across a very interesting journal called “Recent Patents on Biomedical Engineering” to keep me up to date with recent development in this field and read a very interesting article on a new device which I would like to share with the readers of this blog.

This has nothing to do with training and athletic performance, however, considering that in contact sports unfortunately athletes do get injured and may suffer from wounds, I thought this could be something of interest for may of the readers.

The device in question is used to perform a form of therapy called Phototherapy. Phototherapy, the use of light for healing, has in recent years been a field of advanced multidisciplinary research. This modality has been shown to be beneficial in a wide and diverse array of maladies including the healing of chronic and acute wounds, as demonstrated in the use of laser light and LED (Light Emitting Diode) technology. Many in-vitro studies and animal models have shown the promising effects of phototherapy on wound healing. Human studies with laser light have demonstrated greater amounts of epithelialization for wound closure and stimulation of skin graft healing (Conlan MJ, Rapley JW, Cobb CM. Biostimulation of wound healing by low-energy laser irradiation. J Clin Periodont 1996; 23: 492-496; Whelan HT, Smits RL Jr, Buchman EV, et al. Effect of NASA light-emitting diode irradiation on wound healing. Clin Laser Med Surg 2001; 9: 105-14).

Visible and near IR light can be absorbed by cellular photosensitizers such as cytochromes and flavins/riboflavins . Absorption of light by these photosensitizers causes their excitation and relaxation by transferring electrons to O2, thereby generating reactive oxygen species (ROS). ROS are probably best known in biology for their ability to cause oxidative stress. They can damage DNA, cell membranes and cellular proteins and may lead to cell death. However, low ROS fluxes play an important role in the activation and control of many cellular processes, such as the release of transcription factors, gene expression, muscle contraction and cell growth (Rhee SG. Redox signaling: hydrogen peroxide as intracellular messenger. Exp Mol Med 1999; 31: 53-59). Therefore, it makes sense that an appropriate does of phototherapy could be beneficial for wound healing (and I would like also to add…if specific light wavelengths can be reach deep enough muscle healing?).

Various devices have been implemented in phototherapy, especially in wound healing. The most prevalent to date are low level lasers (~10mW/cm^2) and LEDs which typically produce low energy intensities (10-50 mW/cm^2) at a band width of around 10 nm. Broadband light emitting systems with visible-range and near IR only were neglected until recently due to the potential of broadband stimulators (400-800nm) to determine photobiostimulation.

In the paper presented by Lubart et al. (2008)  a new device consisting of a halogen lamp with appropriate filters for the UV and IR wavelengths, and emitting light only in the visible and near IR region, 400-800 nm was tested on diabetic patients and patients with chronic ulcers.The authors state that the ability to irradiate large areas is very important for wound-healing and for killing bacteria, in contradistinction to the narrow laser or LED beam. Another advantage is its low cost, which will enable patients to purchase it for home use.

The results are quite impressive (images from Recent Patents on Biomedical Engineering 2008, 1, 13-17):

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Also, this light setup was capable of sensibly capable of eradicating bacteria on the wound.

Interesting field, I definitively need to read more about this as I am sure there are new ways to speed up tissue repair which may benefit athletes!