Exercise efficiency relates with mitochondrial content and function in older adults. Issue 6 (9th June 2015)

• Record Type: Journal Article
• Authors: Broskey, Nicholas T.; Boss, Andreas; Fares, Elie‐Jacques; Greggio, Chiara; Gremion, Gerald; Schlüter, Leo; Hans, Didier; Kreis, Roland; Boesch, Chris; Amati, Francesca
• Is Part Of: Physiological reports. Volume 3:Issue 6(2015:Jun.)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2015-06-09
• Subjects: Chronic exercise -- delta efficiency -- gross efficiency -- net efficiency; Physiology -- Periodicals; 571
• DOI: 10.14814/phy2.12418
• Languages: English
• ISSNs: 2051-817X

Abstract

Abstract: Chronic aerobic exercise has been shown to increase exercise efficiency, thus allowing less energy expenditure for a similar amount of work. The extent to which skeletal muscle mitochondria play a role in this is not fully understood, particularly in an elderly population. The purpose of this study was to determine the relationship of exercise efficiency with mitochondrial content and function. We hypothesized that the greater the mitochondrial content and/or function, the greater would be the efficiencies. Thirty‐eight sedentary (S, n = 23, 10F/13M) or athletic (A, n = 15, 6F/9M) older adults (66.8 ± 0.8 years) participated in this cross sectional study. V ˙ O2peak was measured with a cycle ergometer graded exercise protocol (GXT). Gross efficiency (GE, %) and net efficiency (NE, %) were estimated during a 1‐h submaximal test (55% V ˙ O2peak ). Delta efficiency (DE, %) was calculated from the GXT. Mitochondrial function was measured as ATPmax (mmol/L/s) during a PCr recovery protocol with 31 P‐MR spectroscopy. Muscle biopsies were acquired for determination of mitochondrial volume density (MitoVd, %). Efficiencies were 17% (GE), 14% (NE), and 16% (DE) higher in A than S. MitoVD was 29% higher in A and ATPmax was 24% higher in A than in S. All efficiencies positively correlated with both ATPmax and MitoVd. Chronically trained older individuals had greater mitochondrial content and function, as well as greater exercise efficiencies. GE, NE, and DE were related to both mitochondrial content and function. This suggests a possible role of mitochondria in improving exercise efficiency in elderly athletic populations and allowing conservation of energy at moderate workloads. Abstract : Active older adults have higher exercise efficiency than age‐matched sedentary counterparts. This is also true for both mitochondrial content and function. Elderly who are more athletic can exercise more efficiently and utilize a lesser amount of energy for a given power output; thus, conserving energy stores and exerting less effort. This can be explained by a higher amount of mitochondria occupying their skeletal muscle volume as well as a faster ability to regenerate ATP. Continuous exercise at an older age can possibly ameliorate the conditions of disease states attributed to decreases in mitochondrial function by increasing mitochondrial content, function, and whole‐body efficiency.