ciao Roberto,che ne pensi del PowerBreathe Plus?
come altri prodotti di questo tipologia hanno un limite "funzionale" nella loro specificità e trasposizione di effetto su prestazione che non sia l'esercizio in sé (=respirare senza carico contro resistenza)
1) far lavorare la muscolatura intercostale creando una resistenza artificiale e in ogni caso mai simile a quella di intensità da sforzo reale
2) esercitare in maniera settoriale la muscolatura respiratoria senza però avere una completa "attivazione" del sistema cardiocircolatorio (= effettivo incremento Vo2max)
The Powerbreathe is an inspiratory muscle trainer promoted as improving inspiratory muscle strength (and consequently exercise performance) in athletes and patients with respiratory disease. No published evidence supports its efficacy. We performed a prospective randomized controlled study in which 12 normal subjects received either Powerbreathe training or sham training for a 6-week period. The primary outcome measure was diaphragm strength evaluated as twitch transdiaphragmatic pressure (Tw Pdi) but secondary outcome measures were provided by full respiratory muscle assessment and cardiopulmonary exercise testing. An advantage to training was observed when outcome was assessed by maximal static inspiratory mouth pressure (mean advantage 14.5 cm H2O, 95% CI 2.2-26.9 cm H2O, P=0.025). However. no significant difference was observed between the groups in any other parameter. In particular the deltaTw Pdi was not different between groups (mean 'advantage' 0.7 cmH2O, 95% CI- 7.0+/-5.5 cmH2O, P=0.8). The continued sale and use of the Powerbreathe device is not justified by our data. A sample size calculation showed that 234 subjects would need to be randomized to definitively refute the hypothesis that Powerbreathe improves Tw Pdi and we argue that such a study is required.
non li cito singolarmente, ma per chi è curioso:Is ventilation volume a limiting factor to maximal endurance?
Sometimes you hear people say "I ran out of wind." Is that really possible? Can we reach a point in exercise when ventilation just can't keep up with demand? The answer is no, assuming you don't have acute asthma or some other severe pulmonary dysfunction. We can measure a person's maximal voluntary ventilation (MVV), the maximal volume of air they can breath in and out while at rest, and compare it with their maximal ventilation during exercise. What we see is that untrained people only use about 60 to 85% of their maximum ventilatory capacity even at maximal exercise. For example the MVV for an average male might be nearly 200 l/min. However, during a treadmill VO2 max test, they reach a peak ventilation of only 140 l/min. Highly trained athletes use more of their capacity, perhaps over 90%, but ventilation capacity is still not a limitation on performance. Unlike the story with cardiac output, even during maximal exercise, the ventilatory capacity is not maxed out.
http://www.ncbi.nlm.nih.gov/pubmed/19780375
http://www.ncbi.nlm.nih.gov/pubmed/18974712
http://www.ncbi.nlm.nih.gov/pubmed/18603575
http://www.ncbi.nlm.nih.gov/pubmed/11504589
http://www.ncbi.nlm.nih.gov/pubmed/11421512
http://www.ncbi.nlm.nih.gov/pubmed/17874123
http://www.ncbi.nlm.nih.gov/pubmed/18641709
http://www.ncbi.nlm.nih.gov/pubmed/10912887
http://www.ncbi.nlm.nih.gov/pubmed/18308881
http://www.ncbi.nlm.nih.gov/pubmed/15322855
http://www.ncbi.nlm.nih.gov/pubmed/21988265
http://www.ncbi.nlm.nih.gov/pubmed/21347970
http://www.ncbi.nlm.nih.gov/pubmed/20351576
http://www.ncbi.nlm.nih.gov/pubmed/19841931
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