Intense interval training in healthy older adults increases skeletal muscle [H-3]ouabain-binding site content and elevates Na+,K+-ATPase alpha(2) isoform abundance in Type II fibers
AuthorWyckelsma, VL; Levinger, I; Murphy, RM; Petersen, AC; Perry, BD; Hedges, CP; Anderson, MJ; McKenna, MJ
Source TitlePhysiological Reports
University of Melbourne Author/sLevinger, Itamar
AffiliationMedicine and Radiology
Document TypeJournal Article
CitationsWyckelsma, V. L., Levinger, I., Murphy, R. M., Petersen, A. C., Perry, B. D., Hedges, C. P., Anderson, M. J. & McKenna, M. J. (2017). Intense interval training in healthy older adults increases skeletal muscle [H-3]ouabain-binding site content and elevates Na+,K+-ATPase alpha(2) isoform abundance in Type II fibers. PHYSIOLOGICAL REPORTS, 5 (7), https://doi.org/10.14814/phy2.13219.
Access StatusOpen Access
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-1J-1) was unchanged. Muscle NKA content increased by 11% after IIT (P < 0.05). Single fiber measurements, increased in NKA α2 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 α2 abundance in Type II fibers, coincident with increased muscle NKA content and enhanced exercise performance.
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