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Training to increase energy supplies

The demands of the game include short sprints, slow jogging, acceleration, using upper body strength, fast striding, jumping, walking, changing direction, rapid recovery, and the ability to interchange between any of these activities on demand. As a result, all of the energy-producing systems within the body are placed under a certain degree of stress, and thus an elite player needs to be an all-around athlete.

Energy systems: the short-term...

However, it is not clear what the relative demands of the three main energy systems are. The short-term energy system (phosphocreatine) is undoubtedly under great stress. This system typically provides most of the energy when one exercises maximally for less than 20 seconds and is therefore central to performance during rugby union. Oxygen is not directly used in this energy production process. The energy-supplying substrate (creatine phosphate) is found within the muscle fibres, and the amount stored and the rate at which it can be used improve with specific training. The training necessary is that which uses these muscle stores repeatedly - not surprisingly, fast running bouts of 5-20 seconds duration, with at least 30 seconds (and up to two minutes) rest to replenish most of the stores between bouts. Undoubtedly, many will already see the possible application of dietary creatine supplements in improving performance in rugby union and other similar sports requiring high-intensity intermittent exercise. Experts agree that athletes competing in such sports may most likely benefit from creatine supplementation.

...and the intermediate...

Muscle glycogen is the initial substrate, lactic acid is the end product, and no oxygen is directly involved. The intermediate energy system, which provides the majority of energy for a sustained performance lasting between 20 seconds and two minutes, is known as either anaerobic glycolysis or the lactic acid system. While unable to produce as much energy per unit time as the phosphocreatine system (i.e. unable to sustain maximum sprinting speed), it lasts considerably longer before intensity must be further reduced. The only way to ensure that this energy system has been taxed significantly is to measure muscle or blood lactic acid levels during or after exercise. Although a few studies have attempted this in other team sports such as soccer, rugby union has yet to be studied in this way. Therefore, it remains a matter of opinion, even after carefully analysing competitive matches on videotape, as to whether the lactic acid system is being used significantly during rugby matches.

Earlier studies from soccer matches suggested only moderate use of the lactic acid system. Still, more recent research has shown that a significant part of energy production is achieved this way. Smith and West Sussex Institute of Higher Education colleagues reported average blood lactate levels of 2.5-10 mmol per litre throughout a college soccer match - well above resting values (about one mmol per litre) and a clear indication of the use of the lactic acid system.

How applicable these findings are to rugby union can only be a guess, but the sports compare reasonably well in terms of player movement. Even though both sports require individual exercise bouts of less than 10 seconds, the soccer players used the lactic acid system. The likely reason for this is the REPEATED nature of the exercise, with probably insufficient time available for the total replacement of creatine phosphate within the muscle. Thus, while accepting that the scientific evidence is scarce at the moment, one can surmise that the lactic acid system is also used in rugby union, though perhaps second in importance to the short-term (phosphocreatine) system. Training programmes should, therefore, try to develop the lactic acid system, which is most easily achieved by interval training. For example, 2 x 5 x 200 in 30 sees, with 60 sees recovery and 15 minutes between sets, would be appropriate for, say, a back-row forward. The 30 seconds can be adjusted to allow for an individual's fitness level while remembering that the last repetitions in each set should require maximal effort.

...and the long-term

The long-term energy system - the aerobic system - is not a significant energy source during most competitive phases of a rugby union match. It is clear from their high intensity and short duration. Nevertheless, a game is 80 minutes long, and thus nearly all the energy provided by the other two systems must be paid for aerobically before the match is over. Ultimately, all exercise has an oxygen cost, and the faster this can be met during recovery, the better the preparation for the next high-intensity exercise bout. Delivery of oxygen to the tired muscles replenishes stores of creatine phosphate and lowers lactic acid levels. This means the aerobic system must not be overlooked in players' preparation.

However, it is rarely a demand for the game to sustain a high rate of energy production in a purely aerobic manner. One can question, therefore, the value of increasing a player's "anaerobic threshold" - in other words, the speed at which he can run without using the lactic acid system excessively. Perhaps more important is the total rate at which oxygen can be transported to the RECOVERING muscles BETWEEN exercise bouts. This can be measured more directly as VO2 max.

This contradicts the accepted wisdom regarding endurance athletes, for whom the anaerobic threshold has assumed more importance than VO2 max. When rugby players who intend to exercise above their anaerobic threshold are considered, their needs are notably different. Recent research suggests that VO2 max, not the anaerobic threshold, is the most critical aspect of aerobic fitness for rugby players. The implications of this might change some players' attitudes toward training.

Recommendations would now include at least one relatively long (30-40 minutes) slow, steady run a week, at a pace that would allow one to hold a conversation - designed to stimulate the use of fats for energy and develop the muscle enzymes involved in this. Also, one would recommend a session of interval training designed to increase VO2 max, such as 6 x 3-minute efforts at a speed fast enough to produce maximal heart rates, with 3-minute rests between repetitions. One would NOT recommend a sustained run (e.g. 30 minutes) at a fast pace that induces fatigue because this sort of "anaerobic threshold" training appears irrelevant to the demands of rugby union. It should be remembered, of course, that many other team sports have similar physiological requirements to rugby union, and the training ideas are given here can be transferred quite easily with fine-tuning to apply to each player in each sport.

Training for explosive power

How much strength does a rugby union player need to perform at the highest level? Some of the data given last month will help to answer this question. However, a more practical individual approach would be to take this view: a player will be better if he is stronger, provided his overall ability to play the game is not damaged. This means that a training balance is necessary. A periodisation plan can help develop this, concentrating on strength qualities during the off-season and focusing more on power and speed before and during the competitive season.

In more detail, one must consider the need for general or specific strength. The specificity of muscles used, the range of motion and speed of movement is thought by many to be necessary, and some training like this is undoubtedly beneficial. Do the benefits of a general strength training programme transfer easily to the sporting situation? Or should a centre, for example, spend most of his time simulating a sprint in the gym, using light dumbbells that can be moved at a similar speed to his arms in a match?

However, King (1993)[1] suggests that strength training is not as specific as many would believe and that the exposure to maximal loading should not be continually compromised for the apparently "specific" exercises with lighter loading. One must remember that strength training aims to get STRONG, and the necessary overload to the muscles requires heavy loads to stimulate optimal adaptation.

Power is perhaps the most effective form of athletic strength - the ability to move the weight quickly. The "explosive power" that characterises many of the demands of rugby by definition requires the player to be strong. As Ian King suggests, the most important aspect of strength training for explosive power is that the athlete consciously and maximally attempts to move the load as fast as possible during the concentric phase of weight training, independent of the apparent speed of the motion then produced. In practice, this means choosing a load suitable for maximal strength gains (e.g. 80-90% of 1-RM for 3-5 repetitions) and performing the exercise as fast as possible during the concentric phase, returning under control during the eccentric phase. The concentric action may not be "fast", but it will be as fast as possible and therefore powerful. Variations in load should range between 70-110% of 1-RM, anything less not being classed as "strength training". King (1993)[1] sums it up thus: "Use strength training to get strong. Play rugby and rugby-related drills to develop specific strengths and conditioning".

A new ergogenic aid

No one who has watched top-level rugby in the last couple of months will have missed spotting the "nose strips" used by the players. The supposed benefits are widening the nostrils, reducing airflow resistance, and allowing more natural breathing (the strips were developed initially to assist sleep and help people with breathing problems). Are they of any use? Scientific research has shown that the function of the muscles and the cardiovascular system are the limiting factors in healthy human performance. Research many years ago showed that if a resting athlete voluntarily hyperventilates, they can supply air to the lungs at a greater rate than that demanded by maximal exercise.

Similarly, even when athletes exercise maximal capacity, they can breathe faster or deeper when asked to do so. Again, this suggests that the volume of air transferred in and out of the lungs is not a limiting factor to performance. At first glance, the theoretical basis for using the nose strips is relatively weak. However, the psychological argument is strong since no elite athlete wants to be disadvantaged by missing out on any potential ergogenic aid. Hence, the widespread use of nose strips.


  1. King, I. (1993) New Zealand Journal of Sports Medicine, 4, p. 62-65

Page Reference

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  • MACKENZIE, B. (2005) Training to increase energy supplies [WWW] Available from: [Accessed