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Specific respiratory muscle training for athletic performance
Issue: Volume 27 Number 4
Today, elite athletes from various endurance sports, including cycling, swimming, rowing and athletics, undertake specific training for the breathing muscles, hoping to improve their competitive results. However, the effectiveness of such training has often been questioned. The following article aims to describe the current understanding of specific respiratory muscle training; how it is done, how it could improve athletic performance and whether it might be more useful for certain athletes than others.
Why train the respiratory muscles?
During exercise the body’s demand for oxygen increases and our breathing volume or ventilation must also rise. This requires numerous muscles surrounding the lungs to contract in a highly coordinated manner. As the intensity of exercise increases, these respiratory muscles must contract more forcefully and more rapidly to keep pace with the body’s substantial increase in metabolism. This important role of the respiratory muscles has generated great interest in the link between respiratory muscles fitness and ‘whole-body’ exercise capacity.
Specific respiratory muscles training
Specific training for the respiratory muscles is completed independent of normal whole-body exercise (such as running or swimming) and is generally carried out in one of two ways. The first method, isocapnic hyperpnoea, requires the individual to breathe at an increased volume of ventilation for an extended period. This training method is similar to the breathing demands of endurance exercise and primarily helps develop respiratory muscles endurance. The second method, threshold loading, focuses on building respiratory muscles strength by breathing for short durations against a resistance. This is a similar approach to traditional weight training. Devices allowing either form of training to be completed are now commercially available (Table 1).
Early studies examining respiratory muscles training demonstrated that both the strength and endurance of the respiratory muscles could be greatly enhanced, and that improvements were specific to the type of training undertaken. This finding has been widely supported, with impressive improvements in respiratory muscles strength and endurance regularly shown, even in well-trained athletes (Sonetti et al. 2001). Importantly, this indicates there is potential for improved respiratory muscles function, even in those individuals who undertake heavy physical training on a regular basis.
Table 1: Summary of the two most common forms of specific respiratory muscles training utilised to enhance athletic performance.
|
Respiratory muscles training type |
Training focus |
Positives |
Negatives |
|
Isocapnic hyperpnoea |
respiratory muscles endurance |
Specific to exercise Possibly enhanced exercise capacity |
Cost (approximately AUD $1000). Training duration (20 – 30 minutes) Technically difficult |
|
Threshold loading |
respiratory muscles strength |
Cost (approximately AUD $150) Training duration (5 – 10 minutes) Technically simple Possibly enhanced exercise capacity |
Non-specific to exercise |
Do athletes really need a greater respiratory muscles capacity?
Despite these positive results, physiologists widely believe that the healthy respiratory system is overbuilt for exercise. This theory is supported by the fact that humans never reach their maximum capacity for ventilation during exercise. Furthermore, for many years it remained unclear whether exercise leading to whole-body fatigue actually resulted in specific fatigue of the respiratory muscles. However, a series of recent studies has confirmed that heavy endurance exercise (>8 – 10 minutes) completed to exhaustion results in fatigue of the diaphragm, the main breathing muscle, for up to 60 minutes (Johnson et al. 1993). While this finding is significant, a number of studies suggest that respiratory muscles fatigue is also linked to the duration of exercise performed. Importantly, research indicates that respiratory muscles fatigue (independent of whole-body fatigue) reduces the ability to complete endurance exercise. This suggests that, if we are able to offset or delay respiratory muscles fatigue during exercise, whole-body performance may improve.
The effects of specific respiratory muscles training on athletic performance
Based on the above findings, it appears that improving the functional capacity of the respiratory muscles would be an important factor in optimising athletic performance. However, results from respiratory muscles training research have not always supported this theory. Despite some negative findings, a number of recent, well-controlled studies have found that both the strength and endurance of the respiratory muscles may limit the whole-body exercise performance of well-trained athletes.
Endurance sports
Most studies supporting the use of respiratory muscles training have utilised high-intensity endurance exercise as the performance measure. For example, one group of cyclists were able to complete a 20-kilometre and 40-kilometre time-trial 65 and 114 seconds faster following six weeks of respiratory muscles strength training (Romer et al. 2002). In another study, five weeks of respiratory muscles endurance training prolonged constant load (85 per cent VO 2max) cycling endurance time by 3.2 minutes (McMahon et al. 2002).
Intermittent sports
Although more investigation into the use of respiratory muscles training for team sports is required, it appears the demands of intermittent sprint exercise may also pose a significant challenge to respiratory muscles function. In the only respiratory muscles training study which examines team-sport athletes, enhanced respiratory muscles strength resulted in a small decrease in self-selected recovery time during a test requiring fifteen 20-metre repeated sprints (Romer et al., IJSM, 2002).
The warm-up effect
Specific respiratory muscles exercise immediately before whole-body exercise may also help improve performance. In an interesting study, a short bout of low-resistance breathing exercises was added to the standard warm-up for a group of well-trained rowers. During a maximal six-minute rowing test, average power output was shown to increase, while measures of breathing discomfort decreased (Volianitis et al. 2001). It appears that, similar to the peripheral muscles, the respiratory muscles may benefit from a warm-up specific to the requirements of athletic competition.
Unclear mechanisms
One of the major downfalls of respiratory muscles training research to date is the lack of concrete evidence explaining how this form of training actually helps enhance physical capacity. What is clear is that respiratory muscles training does not result in improvements in the standard laboratory markers of endurance performance such as VO 2max or lactate threshold, leaving researchers to speculate on potential mechanisms of action.
It is commonly thought that any increase in respiratory muscles capacity should lower the relative load placed on the respiratory muscles during exercise, reducing the incidence of respiratory muscles fatigue. Additionally, this reduced load may result in lower blood-flow and oxygen requirements by the respiratory muscles during exercise. During intense exercise (near VO 2max), this may indirectly improve performance by allowing more of the limited oxygen supply to be used by the exercising peripheral muscles. Finally, breathing discomfort or dyspnoeais a common symptom of heavy endurance exercise, and has been implicated in exercise limitation. While the link between such sensations and performance are still being investigated, respiratory muscles training has commonly been shown to reduce the symptoms of dyspnoea during whole-body exercise (Romer et al. 2002; Romer et al., IJSM, 2002).
Which sports might benefit from respiratory muscles training?
Our current understanding of this area of research suggests that some specific sports and physical activities may benefit from specific respiratory muscles training. Below (Table 2) is a summary of athletic performance requirements that have been shown either to elicit respiratory muscles fatigue or to derive a performance benefit from respiratory muscles training.
Table 2: Situations in which specific respiratory muscle training may improve athletic performance
|
Performance requirement |
Sporting examples |
|
Intense endurance exercise (>80 per cent |
Rowing, 5 – 10 kilometres running, 800 – 1500-metre swimming |
|
Exercise to, or near exhaustion |
Rowing, time-trial cycling, middle distance athletics |
|
Intermittent high-intensity exercise |
Team sports (such as football, hockey and basketball) |
|
Long duration exercise (>2 hours) |
Triathlon, marathon, cycling |
|
Immediately before events requiring heavy breathing efforts (specific respiratory muscles warm up) |
Rowing, swimming, team sports |
Careful conclusions
Regardless of the proposed benefits of specific respiratory muscles training, it is generally conceded that the influence of such training on performance is likely to be small. For this reason, it may not be wise to undertake specific respiratory muscles training at the expense of traditional methods of physical training. However, if your fitness levels are well-developed, and your sport satisfies one or more of the requirements listed in Table 2, specific respiratory muscles training may provide you with an extra performance edge.
References
Johnson, BD, Babcock, MA, Suman, OE and Dempsey, JA 1993. ‘Exercise-induced diaphragmatic fatigue in healthy humans’, Journal of Physiology, 460:385 – 405.
McMahon, ME, Boutellier, U, Smith, RM and Spergler, CM 2002. ‘Hyperpnea training attenuates peripheral chemosensitivity and improves cycling endurance’, Journal of Experimental Biology, 205(pt 24):3937 – 43.
Romer, LM, McConnell, AK and Jones DA 2002. ‘Effects of inspiratory muscle training on time-trial performance in trained cyclists’,Journal of Sports Sciences, 20(7):547 – 62.
Romer, LM, McConnell, AK and Jones, DA 2002. ‘Effects of inspiratory muscle training upon recovery time during high intensity, repetitive sprint activity’, International Journal of Sports Medicine, 23(5):353 – 60.
Sonetti, DA, Wetter, TJ, Pegelow, DF and Dempsey, JA 2001. ‘Effects of respiratory muscle training versus placebo on endurance exercise performance’, Respiration Physiology, 127(2 – 3):185 – 99.
Volianitis, S, McConnell, AK, Koutedakis, Y and Jones, DA 2001. ‘Specific respiratory warm-up improves rowing performance and exertional dyspnea’, Medicine and Science in Sports and Exercise, 33(7):1189 – 93.
