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Sometimes in life you need to read between the lines or gather up all the throw away comments and see what you end up with. So it is with respiratory muscle training (RMT) devices and freediving. Of the three units reviewed here only the PowerLung is both an inspiratory expiratory trainer - resistance on both "suck" and "blow". PowerBreathe and Ultrabreathe are inspiratory trainers only. All claim to improve athletic performance through strengthening the muscles involved in breathing. And all reference research into the effects of RMT on anaerobic and aerobic activity. On the one hand freediving is an anaerobic activity - no oxygen due to the absence of breathing. On the other hand it can be viewed as aerobic activity - high efficiency in the use of the available oxygen is required. But RMT research views anaerobic activity as exercise of high intensity. Hardly a fitting description of the almost meditative sport of freediving. And RMT research looks at aerobic activity in light of prolonged submaximal exercise. In breath-hold, seven minutes is an eternity, in submaximal exercise it isn't even a warm-up. Despite these discrepancies, there are nuggets of information to be extracted from the reading. Suzuki and Okubu (1991) note a reduction in fatigue in both inspiratory and expiratory muscles after expiratory resistance training. By contrast, O'Kroy and Coast (1993) conclude that non-resisted hyperventilation and resisted inspiratory training are more effective than resisted expiratory training in eliciting improved strength and endurance of the breathing muscles. Work by Cain and McConnell (1998) demonstrated a 45% increase in inspiratory muscle strength and 25% increase in resistance to fatigue after four (4) weeks of training with an inspiratory training device. Boutellier (1998) shows a significant increase in breathing muscle fatigue resistance and improved whole body performance when tested on stationary bicycles following respiratory training. A very recent study by Amonette and Dupler (2001) confirm previous findings. This is where the neurological and/or psychological effects of the RMT devices come into play. Boutellier (1998), Gorman, McKenzie and Gandevia (1999) and Yan (1999) all report a reduction in the "urge to breathe". Boutellier's subjects lost the sensation of "breathlessness" after RMT. Gorman, McKenzie and Gandevia's testing group had "discomfort" related to carbon dioxide accumulation and "sensations" generated by increased lung pressures. Yan confirms that these "perceived inspiratory difficulty" can be limited through increased respiratory muscular strength and endurance. Which takes us full circle back to the RMT devices. This is all well and good and may explain how the RMT devices can increase the time to the first "involuntary contraction" - which is remarkably unvaried between individuals and is strongly related to the oxygen/carbon dioxide balance in the blood - but only deals with the first half of a typical breath-hold. But how does the conscious mind stop the body from taking the next breath? I have been led to believe my old training partner, the PowerBreathe, is no longer available. Of the two inspiratory trainers, I felt that the PowerBreathe was the more "substantial" - a more robust unit with a comfortable "pistol grip". Three stars for the most familiar RMT device as a baseline to compare the others to. The second inspiratory muscle trainer, the Ultrabreathe, is light, compact and washes up easily; hygiene is an important consideration with these devices. The Ultrabreathe is very popular with runners in particular. This unit has the advantage of being the least expensive available. This alone scores its third star to bring it level with the PowerBreathe. The PowerLung is a late entry into the heavy market and it is a gem. Heavy-duty build. Comfy grip. Easy to clean. Less "clinical" look. And, the real selling feature, independently adjustable inspiratory and expiratory pressures. An excellent product supported by excellent customer service. Four stars. Would have been five but for the price.
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