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Respiratory muscle training: Effects of training or simple learning?
Respiratory Physiology & Neurobiology 173 (2010) 113–114
Contents lists available at ScienceDirect
Respiratory Physiology & Neurobiology journal homepage: www.elsevier.com/locate/resphysiol
Letter to the Editor Respiratory muscle training: Effects of training or simple learning? To the Editor, We read with great interest the article by Esposito et al. (2010) in the March issue of this Journal. While the authors addressed an important question in respiratory physiology, we would like to offer some methodological suggestions regarding their findings following an 8-week respiratory muscle endurance training (RMET) in healthy subjects. After the training period, pulmonary function parameters as well as maximal inspiratory mouth pressure (PImax ) markedly increased. These findings contrast with the current knowledge based on previous studies investigating RMET in healthy subjects and might therefore not directly be attributed to RMET alone (Keramidas et al., 2010; Leith and Bradley, 1976; Verges et al., 2008, 2009). One could question the low baseline values obtained for PImax and therefore the accurate implementation of the maneuvers. The pre-training PImax values (69 ± 5 cmH2 O) of the subjects, chosen by the best of three maneuvers, were far below of those previously reported in healthy subjects (Leith and Bradley, 1976; Terzi et al., 2009; Uldry and Fitting, 1995; Windisch et al., 2004), however, comparable to values observed in adults with various diseases such as neuromuscular disease, congestive heart failure and idiopathic pulmonary arterial hypertension (Meyer et al., 2001, 2005; Vibarel et al., 2002; Witt et al., 1997). Thus, it seems as if the large increase in PImax might be contributed to technical problems and/or a learning effect, rather than a true training effect. The influence of a learning effect has been extensively studied before (Fiz et al., 1989; Larson et al., 1993; Terzi et al., 2009; Wen et al., 1997). For example, Terzi et al. (2009) observed a session to session learning effect for PImax in healthy subjects with a significant increase for the mean trial number between two sessions, separated by 1 week. In another study, Wen et al. (1997) report that in 65% of the subjects performing PImax , ten or more maneuvers were required to reach peak performance, i.e. three values within 5% variability. In patients with chronic airflow obstruction and unfamiliar with the technique, a minimum of nine maneuvers were needed to obtain peak performance (Fiz et al., 1989). Consequently, the number of maneuvers to reach peak performance in the study by Esposito et al. may not have been adequate for the subjects, and may therefore explain the low baseline values. In addition, the large improvements in pulmonary function reported by the authors could not (fully) be confirmed by previous reports, showing either no (Keramidas et al., 2010; Verges et al., 2008, 2009) or only slight improvements (Verges et al., 2008). Unfortunately, the authors did not mention the criteria
DOI of original article:10.1016/j.resp.2010.02.004. 1569-9048/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.resp.2010.07.007
applied concerning the selection of pulmonary function measurements. Another important fact to be considered is that the RMET program is unlikely to achieve such improvements. The subject’s average training time per session (excluding warm-up) was approximately 6.5 min at the beginning and increased to about 14 min at the end, indicating a quite less elaborate training volume. Controversially, the authors argue that the efficacy of their training protocol is confirmed by the improvements in pulmonary function and PImax while comparing to previous studies using respiratory strength training regimes rather than RMET. In fact, different functional respiratory muscle adaptations have been described for RMET and inspiratory muscle training (IMT) owing to varying muscle recruitment patterns, muscle loads and speeds of contraction. Indeed, increased PImax values were found after IMT (Leith and Bradley, 1976; Romer et al., 2002; Suzuki et al., 1993; Volianitis et al., 2001), however, not RMET so far (Leith and Bradley, 1976; Verges et al., 2008, 2009). We conclude that the results of the study by Esposito et al. should be interpreted with caution, and that the extent of increase in PImax may predominantly be attributed to a learning effect or measurement error. Due to the difficulties associated with these methods, especially in subjects unfamiliar with the technique, there is need to perform an extensive series of maneuvers to assess peak performance. Furthermore, a specific respiratory warm-up may attenuate a learning effect (Volianitis et al., 2001). Finally, it seems obvious that there is a need of more accurate guidelines to non-invasively assess respiratory muscle strength.
References Esposito, F., Limonta, E., Alberti, G., Veicsteinas, A., Ferretti, G., 2010. Effect of respiratory muscle training on maximum aerobic power in normoxia and hypoxia. Respir. Physiol. Neurobiol. 170, 268–272. Fiz, J.A., Montserrat, J.M., Picado, C., Plaza, V., Agusti-Vidal, A., 1989. How many manoeuvres should be done to measure maximal inspiratory mouth pressure in patients with chronic airflow obstruction? Thorax 44, 419–421. Keramidas, M.E., Debevec, T., Amon, M., Kounalakis, S.N., Simunic, B., Mekjavic, I.B., 2010. Respiratory muscle endurance training: effect on normoxic and hypoxic exercise performance. Eur. J. Appl. Physiol. 108, 759–769. Larson, J.L., Covey, M.K., Vitalo, C.A., Alex, C.G., Patel, M., Kim, M.J., 1993. Maximal inspiratory pressure. Learning effect and test–retest reliability in patients with chronic obstructive pulmonary disease. Chest 104, 448–453. Leith, D.E., Bradley, M., 1976. Ventilatory muscle strength and endurance training. J. Appl. Physiol. 41, 508–516. Meyer, F.J., Borst, M.M., Zugck, C., Kirschke, A., Schellberg, D., Kubler, W., Haass, M., 2001. Respiratory muscle dysfunction in congestive heart failure: clinical correlation and prognostic significance. Circulation 103, 2153–2158. Meyer, F.J., Lossnitzer, D., Kristen, A.V., Schoene, A.M., Kubler, W., Katus, H.A., Borst, M.M., 2005. Respiratory muscle dysfunction in idiopathic pulmonary arterial hypertension. Eur. Respir. J. 25, 125–130. Romer, L.M., McConnell, A.K., Jones, D.A., 2002. Effects of inspiratory muscle training upon recovery time during high intensity, repetitive sprint activity. Int. J. Sports Med. 23, 353–360. Suzuki, S., Yoshiike, Y., Suzuki, M., Akahori, T., Hasegawa, A., Okubo, T., 1993. Inspiratory muscle training and respiratory sensation during treadmill exercise. Chest 104, 197–202.
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Letter to the Editor / Respiratory Physiology & Neurobiology 173 (2010) 113–114
Terzi, N., Corne, F., Mouadil, A., Lofaso, F., Normand, H., 2009. Mouth and nasal inspiratory pressure: learning effect and reproducibility in healthy adults. Respiration, doi:10.1159/000254378. Uldry, C., Fitting, J.W., 1995. Maximal values of sniff nasal inspiratory pressure in healthy subjects. Thorax 50, 371–375. Verges, S., Boutellier, U., Spengler, C.M., 2008. Effect of respiratory muscle endurance training on respiratory sensations, respiratory control and exercise performance: a 15-year experience. Respir. Physiol. Neurobiol. 161, 16–22. Verges, S., Renggli, A.S., Notter, D.A., Spengler, C.M., 2009. Effects of different respiratory muscle training regimes on fatigue-related variables during volitional hyperpnoea. Respir. Physiol. Neurobiol. 169, 282–290. Vibarel, N., Hayot, M., Ledermann, B., Messner Pellenc, P., Ramonatxo, M., Prefaut, C., 2002. Effect of aerobic exercise training on inspiratory muscle performance and dyspnoea in patients with chronic heart failure. Eur. J. Heart Fail. 4, 745–751. Volianitis, S., McConnell, A.K., Jones, D.A., 2001. Assessment of maximum inspiratory pressure. Prior submaximal respiratory muscle activity (‘warm-up’) enhances maximum inspiratory activity and attenuates the learning effect of repeated measurement. Respiration 68, 22–27. Wen, A.S., Woo, M.S., Keens, T.G., 1997. How many maneuvers are required to measure maximal inspiratory pressure accurately. Chest 111, 802–807.
Windisch, W., Hennings, E., Sorichter, S., Hamm, H., Criee, C.P., 2004. Peak or plateau maximal inspiratory mouth pressure: which is best? Eur. Respir. J. 23, 708–713. Witt, C., Borges, A.C., Haake, H., Reindl, I., Kleber, F.X., Baumann, G., 1997. Respiratory muscle weakness and normal ventilatory drive in dilative cardiomyopathy. Eur. Heart J. 18, 1322–1328.
Thomas Radtke Christian Benden ∗ Division of Pulmonary Medicine, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland ∗ Corresponding
author. Tel.: +41 44 255 41 83. E-mail address: christian [email protected] (C. Benden)
Contents lists available at ScienceDirect
Respiratory Physiology & Neurobiology journal homepage: www.elsevier.com/locate/resphysiol
Letter to the Editor Respiratory muscle training: Effects of training or simple learning? To the Editor, We read with great interest the article by Esposito et al. (2010) in the March issue of this Journal. While the authors addressed an important question in respiratory physiology, we would like to offer some methodological suggestions regarding their findings following an 8-week respiratory muscle endurance training (RMET) in healthy subjects. After the training period, pulmonary function parameters as well as maximal inspiratory mouth pressure (PImax ) markedly increased. These findings contrast with the current knowledge based on previous studies investigating RMET in healthy subjects and might therefore not directly be attributed to RMET alone (Keramidas et al., 2010; Leith and Bradley, 1976; Verges et al., 2008, 2009). One could question the low baseline values obtained for PImax and therefore the accurate implementation of the maneuvers. The pre-training PImax values (69 ± 5 cmH2 O) of the subjects, chosen by the best of three maneuvers, were far below of those previously reported in healthy subjects (Leith and Bradley, 1976; Terzi et al., 2009; Uldry and Fitting, 1995; Windisch et al., 2004), however, comparable to values observed in adults with various diseases such as neuromuscular disease, congestive heart failure and idiopathic pulmonary arterial hypertension (Meyer et al., 2001, 2005; Vibarel et al., 2002; Witt et al., 1997). Thus, it seems as if the large increase in PImax might be contributed to technical problems and/or a learning effect, rather than a true training effect. The influence of a learning effect has been extensively studied before (Fiz et al., 1989; Larson et al., 1993; Terzi et al., 2009; Wen et al., 1997). For example, Terzi et al. (2009) observed a session to session learning effect for PImax in healthy subjects with a significant increase for the mean trial number between two sessions, separated by 1 week. In another study, Wen et al. (1997) report that in 65% of the subjects performing PImax , ten or more maneuvers were required to reach peak performance, i.e. three values within 5% variability. In patients with chronic airflow obstruction and unfamiliar with the technique, a minimum of nine maneuvers were needed to obtain peak performance (Fiz et al., 1989). Consequently, the number of maneuvers to reach peak performance in the study by Esposito et al. may not have been adequate for the subjects, and may therefore explain the low baseline values. In addition, the large improvements in pulmonary function reported by the authors could not (fully) be confirmed by previous reports, showing either no (Keramidas et al., 2010; Verges et al., 2008, 2009) or only slight improvements (Verges et al., 2008). Unfortunately, the authors did not mention the criteria
DOI of original article:10.1016/j.resp.2010.02.004. 1569-9048/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.resp.2010.07.007
applied concerning the selection of pulmonary function measurements. Another important fact to be considered is that the RMET program is unlikely to achieve such improvements. The subject’s average training time per session (excluding warm-up) was approximately 6.5 min at the beginning and increased to about 14 min at the end, indicating a quite less elaborate training volume. Controversially, the authors argue that the efficacy of their training protocol is confirmed by the improvements in pulmonary function and PImax while comparing to previous studies using respiratory strength training regimes rather than RMET. In fact, different functional respiratory muscle adaptations have been described for RMET and inspiratory muscle training (IMT) owing to varying muscle recruitment patterns, muscle loads and speeds of contraction. Indeed, increased PImax values were found after IMT (Leith and Bradley, 1976; Romer et al., 2002; Suzuki et al., 1993; Volianitis et al., 2001), however, not RMET so far (Leith and Bradley, 1976; Verges et al., 2008, 2009). We conclude that the results of the study by Esposito et al. should be interpreted with caution, and that the extent of increase in PImax may predominantly be attributed to a learning effect or measurement error. Due to the difficulties associated with these methods, especially in subjects unfamiliar with the technique, there is need to perform an extensive series of maneuvers to assess peak performance. Furthermore, a specific respiratory warm-up may attenuate a learning effect (Volianitis et al., 2001). Finally, it seems obvious that there is a need of more accurate guidelines to non-invasively assess respiratory muscle strength.
References Esposito, F., Limonta, E., Alberti, G., Veicsteinas, A., Ferretti, G., 2010. Effect of respiratory muscle training on maximum aerobic power in normoxia and hypoxia. Respir. Physiol. Neurobiol. 170, 268–272. Fiz, J.A., Montserrat, J.M., Picado, C., Plaza, V., Agusti-Vidal, A., 1989. How many manoeuvres should be done to measure maximal inspiratory mouth pressure in patients with chronic airflow obstruction? Thorax 44, 419–421. Keramidas, M.E., Debevec, T., Amon, M., Kounalakis, S.N., Simunic, B., Mekjavic, I.B., 2010. Respiratory muscle endurance training: effect on normoxic and hypoxic exercise performance. Eur. J. Appl. Physiol. 108, 759–769. Larson, J.L., Covey, M.K., Vitalo, C.A., Alex, C.G., Patel, M., Kim, M.J., 1993. Maximal inspiratory pressure. Learning effect and test–retest reliability in patients with chronic obstructive pulmonary disease. Chest 104, 448–453. Leith, D.E., Bradley, M., 1976. Ventilatory muscle strength and endurance training. J. Appl. Physiol. 41, 508–516. Meyer, F.J., Borst, M.M., Zugck, C., Kirschke, A., Schellberg, D., Kubler, W., Haass, M., 2001. Respiratory muscle dysfunction in congestive heart failure: clinical correlation and prognostic significance. Circulation 103, 2153–2158. Meyer, F.J., Lossnitzer, D., Kristen, A.V., Schoene, A.M., Kubler, W., Katus, H.A., Borst, M.M., 2005. Respiratory muscle dysfunction in idiopathic pulmonary arterial hypertension. Eur. Respir. J. 25, 125–130. Romer, L.M., McConnell, A.K., Jones, D.A., 2002. Effects of inspiratory muscle training upon recovery time during high intensity, repetitive sprint activity. Int. J. Sports Med. 23, 353–360. Suzuki, S., Yoshiike, Y., Suzuki, M., Akahori, T., Hasegawa, A., Okubo, T., 1993. Inspiratory muscle training and respiratory sensation during treadmill exercise. Chest 104, 197–202.
114
Letter to the Editor / Respiratory Physiology & Neurobiology 173 (2010) 113–114
Terzi, N., Corne, F., Mouadil, A., Lofaso, F., Normand, H., 2009. Mouth and nasal inspiratory pressure: learning effect and reproducibility in healthy adults. Respiration, doi:10.1159/000254378. Uldry, C., Fitting, J.W., 1995. Maximal values of sniff nasal inspiratory pressure in healthy subjects. Thorax 50, 371–375. Verges, S., Boutellier, U., Spengler, C.M., 2008. Effect of respiratory muscle endurance training on respiratory sensations, respiratory control and exercise performance: a 15-year experience. Respir. Physiol. Neurobiol. 161, 16–22. Verges, S., Renggli, A.S., Notter, D.A., Spengler, C.M., 2009. Effects of different respiratory muscle training regimes on fatigue-related variables during volitional hyperpnoea. Respir. Physiol. Neurobiol. 169, 282–290. Vibarel, N., Hayot, M., Ledermann, B., Messner Pellenc, P., Ramonatxo, M., Prefaut, C., 2002. Effect of aerobic exercise training on inspiratory muscle performance and dyspnoea in patients with chronic heart failure. Eur. J. Heart Fail. 4, 745–751. Volianitis, S., McConnell, A.K., Jones, D.A., 2001. Assessment of maximum inspiratory pressure. Prior submaximal respiratory muscle activity (‘warm-up’) enhances maximum inspiratory activity and attenuates the learning effect of repeated measurement. Respiration 68, 22–27. Wen, A.S., Woo, M.S., Keens, T.G., 1997. How many maneuvers are required to measure maximal inspiratory pressure accurately. Chest 111, 802–807.
Windisch, W., Hennings, E., Sorichter, S., Hamm, H., Criee, C.P., 2004. Peak or plateau maximal inspiratory mouth pressure: which is best? Eur. Respir. J. 23, 708–713. Witt, C., Borges, A.C., Haake, H., Reindl, I., Kleber, F.X., Baumann, G., 1997. Respiratory muscle weakness and normal ventilatory drive in dilative cardiomyopathy. Eur. Heart J. 18, 1322–1328.
Thomas Radtke Christian Benden ∗ Division of Pulmonary Medicine, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland ∗ Corresponding
author. Tel.: +41 44 255 41 83. E-mail address: christian [email protected] (C. Benden)