Monday, 28 March 2011

Energy and physiological demands of the game of rugby:

In recent years, the advent of an elitist status been attached to many a school sports codes, and more intensely so in the domain of schools rugby. With attractive scholarships, bursaries and the possibility of exposure into the lucrative post secondary, rugby fraternity, more and more of South Africa’s top rugby and sporting schools, have recognised the importance of a professional approach in the management of school boy rugby players. This article will thus focus on an important element, that has had a critical impact on the improved statures of players, enhanced fitness capabilities, and overall increase in the speed and attractiveness of schoolboy rugby, and that being high performance and its building blocks, with an intricate look into the energy demands of the game.
The premise of such an analysis of the game, has been documented, and has proved worthy in developing fitness programmes that target the specific capacities, energy pathways and muscular applications that players are exposed to in match situations. This will also provide the coach with an effective template to ensure an optimal ratio or variation of training to avoid overtraining as well as ensure that each of his players are been taxed appropriately for their specific positional demands.
Rugby is a game that is largely intermittent in nature, and relies on specific athletic prowess in strength, power, agility, speed and endurance. However a detrimentally overlooked component is that of recovery, and its vast effects on performance. It is widely accepted that the building blocks of fitness improvement in any code of sport, is that work which is completed in training. However the work outputs in training are simply exposing the body to increasing, and progressive elements of various stresses (gym training, conditioning, skills), which the body then has to adapt to those same elements its been exposed to (adaptation syndrome). However, it is at rest, during the recovery phases of a training plan, that the body’s hormonal and neuromuscular systems are working hard to ensure that the body is ready to withstand that same stress, if and when it is exposed to it again. Through recovery (rest) and energy replacement (nutrition/diet), that the body is able to reach optimum levels once again, to attack the stress of training again.
In relation to rest and recovery, the main focus of fitness coaches, is to balance the type, volume and intensity of training, with the amount of rest required, so that a player reaches optimal functioning levels before attempting his next training session. This is especially vital in a multidisciplinary game as rugby, where there are many components that need attention at once, and thus the chance of injury due to overtraining is relatively high.
In a study utilising data from The New Zealand Rugby Union (video files, analysis software and primary match analysis from their analysis organisations), analysis and data results were used to  interpret it into usable information for coaches, players and other interested parties (1). This study also allowed coaches to rank players, which essentially is requirement of the selection process, in professional sporting setups.
As previously explained, the game of rugby involves various fitness elements, in a series of bouts involving both high and low intensity bouts over an 80min period. In a nutshell, the study yielded the following results, which depicts the efforts of an international flanker in an 80min match:
-          25 tackles made
-          46 rucks
-          22 scrums pushed
-          24 lineout lifts
In conjunction, it was analysed that players covered an average of 6-8km in a match, at varying speeds, separated into over 200 intervals, over varying distances. The ball was typically in play for 25-35min, consisting of cycles of play with periods of rest, with most play cycles lasting an average of 23 seconds, and the typical range of these cycles is between 5 – 63seconds. The rest periods observed varied in length, with the average being 42 seconds.
Another more in depth analysis of the game itself was expressed by Bompa and Deutsch et al 2006, in the following adapted synopsis:
Limiting factors
Average work/rest ratios
Training objectives.
-          60% aerobic
-          30% anaerobic lactic
-          10% anaerobic alactic

(position specificity must be taken into account)
-          Acceleration
-          Deceleration
-          Change of direction
-          Aerobic/ anaerobic endurance
-          Power/ power endurance
-          Forward – 1:7
-          Backs – 1:21
-          Also note that forwards are involved in more high intensity efforts, whereas backs reach peak velocity more often.
-          3 energy pathway development, with an emphasis on aerobic endurance
-          Develop starting power, and power endurance
-          Develop agility, with quick footwork
-          Develop acceleration and deceleration with changes in direction

Although all players in a match are exposed to similar stressors, it must be taken into account that certain positions or players will be exposed to a specific component, or utilise a specific energy system more often than other players eg, a prop forward will be involved in more close quarter, high intensity efforts, such as rucks, mauls, and short sprints lasting 2-4sec, than an outside back, and thus their specific fitness regimen needs to mimic the elements required for their position to ensure optimal efficacy during matches. Gone are the days when all players followed a standard protocol, whereas now programs and sessions are a lot more focused.
Performance analysis software and templates, aims to answer two specific questions that gives insight to how strength and conditioning programs are developed:
1.       What’s the ratio of high to low intensity activity.
2.       What are the variations of player/ positional work to rest ratios.
Early research on rugby suggested that players spend only 5-10% of match time involved in high intensity activity where the phosphocreatine system predominates. This is the energy system which is able to produce energy for high intensity activity, lasting no more than 6-10secs.
When further broken down into player groups it is observed that forwards perform 3 times more high intensity efforts than backs – 11,2minutes vs 3,6minutes respectively, per match.
In a research article that analysed 29 top class professional rugby union players, filmed during a course of 8 professional Super 12 matches in New Zealand, the following data was analysed and recorded. Players were firstly categorised  into 4 categories, being tight five (excluding hooker), loose trio (including hooker), inside backs and outside backs. The analysis then analysed player movements, within the specific groups, categorising jogging, standing, walking and backward and sidewalking, as low intensity, and rucking, mauling, sprinting, tackling, scrimmaging as high intensity.
They then further analysed the time spent in each category of movement, and the frequency and average time of each individual activity, in the following table:

Front row forwards
Back row forwards
Inside backs
Outside backs
Avg no. Of high intensity efforts in a match
Avg duration of high intensity efforts (in seconds)
Avg duration of low intensity efforts (in seconds)

The chart therefore substantiates what was explained earlier in this article, with regards to the intensity, and work to rest ratios of various positions. The central focus from this table would be to extrapolate the data and interpret it, or use the data to draw up an effective program. For instance, looking at the back row forwards, its evident that they are involved in a substantial amount of high intensity efforts, lasting approximately 5seconds/bout, with relatively short recovery periods between bouts (35seconds) which suggests that the anaerobic system is the dominant system (high intensity exercise which utilises glycogen as the primary energy in the absence of oxygen to replenish reserves). Thus interval training would be an effective endurance tool to utilise, and all one would basically have to do is manipulate distances, intensity (speed), and recovery intervals to mimic the figures shown.
Another key variable to take into account when analysing specific groups, as such, is the type of high intensity activities been performed during the match. For instance, the study also revealed that forwards completed fewer sprints, than the other 3 groups, with backrow forwards and outside backs completing 7 and 11 sprints respectively, on average. Forwards however were involved in other high intensity activities, such as rucks/mauls (75), backrow forwards (57), and inside and outside backs, completing 11 and 7 respectively.
Therefore it is evident that, distinct differences are present between the energy and neuromuscular demands of various positions, and thus lies the premise for an analytical approach to strength and conditioning program design.
In the weeks to come, i will start to break down the specific fitness components required for the game, and link it to the direct match and positional demands, and show some unique insights into various programs and how they can improve your performance on the field.
Bompa. T. 2006. Total Training for Team Sports, Toronto, Sports Books Publishers
Deustsh M., Kearney G., Rehrer N. 2006. Time Motion Analysis of Professional Rugby Union Players during Match Play, Journal Of Sports Sciences, 2006, 1-12
Deutsh et al (1998), Journal of Sports Sciences, 16, 561-570
Agnew. M. 2006. Game Analysis in Rugby Union, Thesis submission, Auckland University of Technology.
Nicholas Orson
Bachelor of Sports Science

Wednesday, 2 March 2011


Hockey players are well aware of the fact that it is a very energy demanding sport.  During a hockey match players can run approximately 7km, depending on their playing position. Furthermore the duration is approximately 70 minutes and a half time of approximately 5 minutes.  Hockey is recurrent in nature and players must perform continuously for the duration of the match.  As you can just imagine (or those who knows) from the above mentioned info, the fact is that hockey takes allot out of you. 

A very high demand is placed on the aerobic systems of the players and thus aerobic endurance is vital to hockey players’ performances.  The energy demands of hockey players are mainly met by aerobic respiration due to the prolonged duration of matches.  In the case of high intensity exercises such as sprint exercises (<10sec), energy will be obtained by anaerobic respiration.
Our body can be compared to that of a car, just as a car needs fuel to generate ‘’energy’’ to produce momentum, so does our body and specifically our muscles need fuel.  Now immediately we think FOOOOOOD, yes food, but the form of fuel that the muscles use is very refined and is called Adenosine TriPhosphate(ATP).  The production of ATP in the muscle cells is formed by using one or a combination of three metabolic pathways:

1.    ATP-PC System
2.    Glycolysis
3.    Oxidative phosphorylation

1.    ATP-PC System
ATPase (enzyme) breaks down ATP; to produce ’’E’’ (energy).
ATP ----------> ATPase ----------> ADP+ P + ’’E’’ 
Short-term, high intensity exercises ( <10sec)
  • Rapid Supply of ATP
2.     Glycolysis
Second metabolic pathway capable of producing ATP rapidly without O2
The breakdown of 1 Glucose molecule forms 2 molecules of Pyruvate OR Lactate and 2 ATP
  • If O2 is absent  ----------> Lactate forms
  • If O2 is present ----------> Pyruvate forms and enter the oxidative phosphorylation system and ATP production is aerobic, as is the case with HOCKEY.
Glycolysis can be considered as the 1st step in aerobic degradation of carbohydrates (glucose) which is the case in HOCKEY.  Thus, in HOCKEY, after the Second Metabolic pathway (glycolysis) or the 1st step of aerobic respiration, the 3rd Metabolic Pathway follows….

-  Oxidative Phosphorylation (aerobic)

3.     Oxidative Phosphorylation
Consists of 3 Stages:  (Simple explanation)       

Stage 1:

Pyruvate, produced by glycolysis which is regarded as the 1st step of aerobic respiration, is converted to Acetyl-CoA (Acetyl Co-Enzyme A) 
[REMEMBER 2 Pyruvate molecules are produced by glycolysis thus 2 Acetyl-CoA are formed by the conversion of pyruvate]

Stage 2:

Acetyl-CoA now enters the Krebs Cycle which, via a cycle of complex reactions then produces:
-      3 molecules NADH
-      1 molecule FADH

Stage 3:

Also known as Electron transport chain/Respiratory Chain.
In this stage NADH and FADH are used to rephosphorylate ADP to form ATP.
[In the end a grand total of 32 ATP molecules are produced aerobically from 1 molecule glucose].Although we only considered glucose now; Protein and fats can also be broken down to form Acetyl-CoA that enter the Krebs cycle to produce ATP.

                                           Figure 1.  Bioenergetic Pathways

This may seem like a lot of irrelevant info that you may not appreciate right now, BUT by understanding the energy systems, it supports and encourages the way in which we develop specific programs to meet specific sports’ energy demands.  The purpose of my blog posts will thus be to assist coaches and players in conditioning aspects to meet the demands of hockey.  These hockey specific training regimes will aim to help improve fitness levels, skills and the performances of individuals and teams. 

Boyle PM, Mahoney CA, Wallace WF. The competitive demands of elite male field hockey. J Sports Med Phys Fitness. 1994 Sep;34(3):235-41
Gabbett, Tim J. GPS Analysis of Elite Women's Field Hockey Training and Competition. Journal of Strength & Conditioning Research: 2010 May; 24(5):  1321-1324.

Reilly T, Borrie A. Physiology applied to field hockey. Sports Med. 1992 Jul;14(1):10-26
Spencer M, Lawrence S, Rechichi C, Bishop D, Dawson B, Goodman C. Time-motion analysis of elite field hockey, with special reference to repeated-sprint activity. J Sports Sci. 2004 Sep;22(9):843-50


BLOG BY:  Elzanne Jacobs (Bachelor of Sport Science)