Open AccessIntense interval training in healthy older adults increases skeletal muscle [ 3 H]ouabain‐binding site content and elevates Na + ,K + ‐ATPase α 2 isoform abundance in Type II fibers
Author(s) -
Wyckelsma Victoria L.,
Levinger Itamar,
Murphy Robyn M.,
Petersen Aaron C.,
Perry Ben D.,
Hedges Christopher P.,
Anderson Mitchell J.,
McKenna Michael J.
Publication year - 2017
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.13219
Subject(s) - ouabain , medicine , rating of perceived exertion , heart rate , skeletal muscle , endocrinology , vo2 max , muscle biopsy , exertion , cardiology , chemistry , biopsy , sodium , blood pressure , organic chemistry
Young adults typically adapt to intense exercise training with an increased skeletal muscle Na + ,K + ‐ATPase (NKA) content, concomitant with reduced extracellular potassium concentration [K + ] during exercise and enhanced exercise performance. Whether these changes with longitudinal training occur in older adults is unknown and was investigated here. Fifteen older adults (69.4 ± 3.5 years, mean ± SD) were randomized to either 12 weeks of intense interval training (4 × 4 min at 90–95% peak heart rate), 3 days/week (IIT, n = 8); or no exercise controls ( n = 7). Before and after training, participants completed an incremental cycle ergometer exercise test until a rating of perceived exertion of 17 (very hard) on a 20‐point scale was attained, with measures of antecubital venous [K + ] v . Participants underwent a resting muscle biopsy prior to and at 48–72 h following the final training session. After IIT, the peak exercise work rate (25%), oxygen uptake (16%) and heart rate (6%) were increased ( P < 0.05). After IIT, the peak exercise plasma [K + ] v tended to rise ( P = 0.07), while the rise in plasma [K + ] v relative to work performed (nmol.L −1 .J −1 ) was unchanged. Muscle NKA content increased by 11% after IIT ( P < 0.05). Single fiber measurements, increased in NKA α 2 isoform in Type II fibers after IIT (30%, P < 0.05), with no changes to the other isoforms in single fibers or homogenate. Thus, intense exercise training in older adults induced an upregulation of muscle NKA, with a fiber‐specific increase in NKA α 2 abundance in Type II fibers, coincident with increased muscle NKA content and enhanced exercise performance.