Author: marcocardinale

I am the Executive Director of Research and Scientific Support in Aspetar (Qatar). The aim of this blog is to present and discuss issues related to sport and sports science.

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!

Monitoring training load in Team Sports: Quo vadis? #1

It is the beginning of the season for many team sports and it is the typical time when sports scientists start to struggle with manipulating the training load and making sure the players can survive a long season producing great performances.

I will try to analyse the current trends in the literature and provide some comments and some possible advice on how to put in place a meaningful and practical monitoring system to be able to inform the coaching process.

It is widely recognised that appropriate periodisation of training is fundamental for
optimal performance in sport. Until recently, it has been very difficult to quantify the
training loads (TLs) in team sports players due to the difficulty in measuring the various types of stress encountered during training and competition. Wearable sensors and well established psychometric tools as well as easy access to field-based biochemistry nowadays allow the collection of various data to be able to quantify and understand the training load as well as track the progression of the players’ performances. This can provide the basis for a critical assessment of the training process and feedback to the players and coaching staff of the progression.

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Few comments before discussing the methods for data collection.

Training monitoring is becoming a standard operating procedure for many strength and conditioning coaches and sports scientists which is a good thing. However there are certain aspects that needs to be taken into consideration in order to understand the limitations of some training monitoring approaches as well as the potential of such methods to impact practice.

The latter is the most important aspect to be taken into consideration. Training monitoring becomes a useful thing to do ONLY if guides practice and informs the coaching process. Otherwise it becomes just a data collection exercise. I have seen many S&C coaches use a variety of tools and tests and despite the fact they have some nice continuous data it is clear that such data did not affect practice as training programmes continued in the same way despite the information available on training load and some effects.

So, first rule: training monitoring is a great way to understand how much work your athletes are doing and how they cope with it. Great thing to do only if it helps you in changing and evaluating your training plans.

The other aspect to consider is the limitations of what you measure, when you measure it and how many time  you measure it. All this information helps in understanding what the information tells you and what parameter of your training programme you should change according to the results observed.

Training monitoring needs two main parameters to be measured:

1) The amount of training your athlete is performing (the INPUT)

2) How the athlete is coping with the amount of training (the OUTPUT)

The INPUT can be measured in various ways and should contain some information on how much work the athlete has performed (such weights lifted in each session, distance covered in training and also the perception of how hard the session has been). The list can be more extensive, but frankly your ability to collect more and better data is limited by the equipment you have access to. Heart rate monitors, GPS and accelerometers, power meters in the gym are all available nowadays and allow a lot of measurements to be collected in team sports to help you gain more info on the intensity and the amount of training performed. I have presented few technologies in this blog and aim to do more in the future, so plenty of solutions for you to try.

However, not many people have access to technology (in particular the expensive software and hardware kits for more complex multisensor data collection). So, let’s discuss some simple training quantification methods and their applications.

This will require the use of spreadsheets to facilitate the calculations and the data collection as well as provide you the possibility to create reports and graphs. If you don’t have access to Microsoft ® Excel don’t worry! You can in fact download open office for free from here and have access to a free suite which allows you to have spreadsheets, graphs and presentations at no cost!

The Session RPE method

The session-RPE method of monitoring TL in team players requires each athlete to
provide a Rating of Perceived Exertion (RPE) for each exercise session along with a measure of training time (as suggested by Foster et al., 2001).

To calculate a measure of session intensity, athletes are asked within 30-minutes of finishing their workout a simple question like “How was your workout?” A single number representing the magnitude of TL for each session is then calculated by the multiplication of training intensity (RPE from Table 1) by the training session duration (mins).

Table 1. The modified RPE scale proposed by Foster et al. 2001

RATING

DESCRIPTOR

0

Rest

1

Very, Very easy

2

Easy

3

Moderate

4

Somewhat Hard

5

Hard

6

7

Very Hard

8

9

10

Maximal

Training Load = Session RPE x duration (mins)

For example, to calculate the TL for a training session 60-minutes in duration with the
athletes RPE being 5, the following calculation would be made:

TL = 5 x 60 = 300 AU (arbitrary units)

With a simple spreadsheet it is is therefore possible to track the training load of a team very easily just by recording the duration of training and making sure that each player at the end of each session provides you with the perceived exertion for that session.

Here is an example of what a score of a typical training period could look like:

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The Black dotted line represents the average Session RPE for the team and each colour represents one of the players. In this way, it is possible to track how the overall training load is progressing and how each individual compares to the team.

The data can also be useful to track down the team’s session RPE and understand if overall the training load is going in the direction planned.

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Further simple calculations of training ‘monotony’ and ‘strain’ can also be made from
session-RPE variables.

Training monotony is a simple measure day to day variability in training that has been suggested to be related to the onset of overtraining when monotonous training is combined with high training loads (see Foster, 1998).

Training monotony is calculated from the average daily TL divided by the standard deviation of the daily TL calculated over a week.

MONOTONY= DAILY TL/SD of TL over a week

Training strain can also be calculated as follows:

TRAINING STRAIN = weekly TL x monotony

The table below provides a simple example of a weekly training load in a semi-professional handball team with all the variables calculated.

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Recent work conducted using RPE from 20 soccer players during 67 small sided-games soccer training sessions (Coutts, Rampinini, Castagna, Marcora, & Impellizzeri, 2007a) has shown that  the combination of blood lactate and HR measures during small-sided games were better related to RPE than HR or blood lactate measures alone. This work suggested that RPE is a valid method of estimating global training intensity in soccer. There isn’t such evidence in other sports, however nothing stops practitioners to try and see if it helps with their coaching process.

This is the first article of a series aimed at discussing the issue of monitoring training. I aim to present practical solutions to be able to start quantifying and understanding adaptations in team sports athletes.

Enough for now, time to get your spreadsheets sorted and start calculating what your players are doing so you are ready to apply the techniques presented in the next article!

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!