Περίληψη:
Study objectives: To investigate the response to interval exercise (IE)
training by looking at changes in morphologic and biochemical
characteristics of the vastus lateralis muscle, and to compare these
changes to those incurred after constant-load exercise (CLE) training.
Design: Randomized, controlled, parallel, two-group study (IE vs CLE
training).
Setting: Multidisciplinary, outpatient, hospital-based, pulmonary
rehabilitation program.
Patients: Nineteen patients with stable advanced COPD (mean +/- SEM
FEV1, 40 +/- 4% predicted).
Interventions: Patients (n = 10) assigned to IE training exercised at a
mean intensity of 124 +/- 15% of baseline peak exercise capacity (peak
work rate [Wpeak]) with 30-s work periods interspersed with 30-s rest
periods for 45 min/d. Patients (n = 9) allocated to CLE training
exercised at a mean intensity of 75 +/- 5% Wpeak for 30 min/d. Patients
exercised 3 d/wk for 10 weeks.
Measurements and results: Needle biopsies of the right vastus lateralis
muscle were performed before and after rehabilitation. After IE
training, the cross-sectional areas of type I and IIa fibers were
significantly increased (type I before, 3,972 +/- 455 mu m(2); after,
4,934 +/- 467 mu m(2) [p = 0.004]; type IIa before, 3,695 +/- 372 mu
m(2); after, 4,486 +/- 346 mu m(2) [p = 0.008]), whereas the
capillary-to-fiber ratio was significantly enlarged (from 1.13 +/- 0.08
to 1.24 +/- 0.07 [p = 0.013]). Citrate synthase activity increased
(from 14.3 +/- 1.4 to 20.5 +/- 4.2 mu mol/min/g), albeit not
significantly (p = 0.097). There was also a significant improvement in
Wpeak (by 19 +/- 5%; p = 0.04) and in lactate threshold (by 17 +/- 5%;
p = 0.02). The magnitude of changes in all the above variables was not
significantly different compared to that incurred after CLE training.
During training sessions, however, ratings of dyspnea and leg
discomfort, expressed as fraction of values achieved at baseline Wpeak,
were significantly lower (p < 0.05) for IE training (73 +/- 9% and 60
+/- 8%, respectively) compared to CLE training (83 +/- 10% and 87 +/-
13%, respectively).
Conclusions: High-intensity IE training is equally effective to
moderately intense CLE training in inducing peripheral muscle
adaptations; however, IE is associated with fewer training symptoms.
Συγγραφείς:
Vogiatzis, I
Terzis, G
Nanas, S
Stratakos, G
Simoes, DCM
and Georgiadou, O
Zakynthinos, S
Roussos, C
