THE EDGE

GAINING THAT EXTRA 1 OR 2% IN PERFORMANCE…LEGALLY

The drugs scandals of the past few months highlight the lengths to which some ath- letes will go for an extra 1 or 2%. The preparation of an elite competitor in today’s professional world of sport is meticulous but there is one vital element being overlooked – breathing.

As students of exercise physiology we are told that breathing does not limit perfor- mance, in the human at least. From the oxygen uptake perspective this is largely true but recent research from both sides of the Atlantic is demonstrating the pro- found effect which the respiratory muscu- lature can have upon performance.

Researchers at the University of Birmingham have demonstrated in care- fully controlled studies of cycling and rowing, that endurance performance (cycling to exhaustion at a fixed work rate) increases by 26% (1) after inspirato- ry muscle training (IMT). In a more ‘real world’ model of performance, both 5000m time and 6 minute all-out rowing perfor- mance improved by over 3% in elite female rowers (5). These gains were achieved by IMT which took no more than 6 minutes per day (2).

IMT is believed to increase performance through a number of ways including reducing breathlessness, a major factor in perceived exertion, which as a conse- quence also falls after IMT. It also induces changes in blood lactate turnover, with post-IMT exercise being associated with significantly lower levels of circulating blood lactate (1).

However potentially more significantly during heavy exercise, breathing increases by around 16-fold and the demands of this can account for 10% of total oxygen uptake and 15% of cardiac output.

Recent work from the John Rankin Laboratory at the University of Wisconsin has demonstrated that during high inten- sity exercise blood flow (and hence oxygen delivery) to locomotor muscles is inverse- ly proportional to respiratory work (4).

In other words, if inspiration is loaded by breathing via an added resistance, blood flow to the working legs goes down. In contrast, if inspiration is assisted using a ventilator, blood flow to the legs goes up. What is more, the extra blood delivered to the legs can be put to good use by increasing the power output equating to maximal oxygen uptake (5). Therefore the inspiratory muscles appear to be capable of stealing blood from the locomotor muscles, and in so doing, impair perfor- mance.

Whilst IMT has only small effect in healthy respiration below the lactate threshold, the story above is very differ- ent, with huge increases in breathing accompanying the ventilatory compensa- tion for metabolic acidosis. By definition, the latter can only be sustained for very brief periods and perhaps not long enough, or with sufficient frequency to elicit a full training adaptation from the inspiratory muscles. In addition, with regard to improvements in strength and power, unloaded breathing does not pro- vide sufficient overload; it’s akin to a bicep curl without the dumbbell.

IMT is now being used by the likes of the England rugby squad, British Triathlon Association, and numerous top track ath- letes, rowers and swimmers.

Two of the UK’s leading respiratory train- ers include the POWERbreathe® trainer developed by sports scientists at Birmingham University and the RT Sport®

Respiratory trainer which recently won the Design Week Industrial Product Award for 1999.

Dr Alison McConnell is a part-time research fellow at the University of Birmingham and research director of IMT Technologies Ltd. Her team is engaged in an ongoing programme of research on respiratory limitation(s) to performance which led to the develop- ment of the POWERbreathe® Inspiratory Muscle Trainer. Alison is also a BASES and British Olympic Association Accredited Sports Scientist.

max with respiratory muscle unloading’. Med. Sci. Sports Exerc. 1998;30:A239 4. Harms et al. ‘Effect of respiratory muscle work on cardiac output and its distribution during exercise’. J. Appl. Physiol. 1997;82:1573-1583 5. Volianitis et al. ‘Inspiratory muscle train- ing improves rowing performance’. Presented at the Eur. Coll. of Sports Sci. meeting, July 1999, in press

References 1. Caine & McConnell. ‘Pressure threshold inspiratory muscle training improves sub- maximal cycling performance’. Presented at the Eur. Coll. Sports Sci. meeting, July 1998, in press 2. Caine & McConnell. ‘The inspiratory mus- cles can be trained differentially to increase strength or endurance using a pressure threshold inspiratory muscle training device’. Eur. Resp. J. 1998;12:58s 3. Harms et al. ‘Increased power output at VO2

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