PMID- 26460630
OWN - NLM
STAT- MEDLINE
DCOM- 20170109
LR  - 20181113
IS  - 1530-0315 (Electronic)
IS  - 0195-9131 (Print)
IS  - 0195-9131 (Linking)
VI  - 48
IP  - 3
DP  - 2016 Mar
TI  - Muscle Characteristics and Substrate Energetics in Lifelong Endurance Athletes.
PG  - 472-80
LID - 10.1249/MSS.0000000000000789 [doi]
AB  - PURPOSE: The goal of this study was to explore the effect of lifelong aerobic 
      exercise (i.e., chronic training) on skeletal muscle substrate stores 
      (intramyocellular triglyceride [IMTG] and glycogen), skeletal muscle phenotypes, 
      and oxidative capacity (ox), in older endurance-trained master athletes (OA) 
      compared with noncompetitive recreational younger (YA) athletes matched by 
      frequency and mode of training. METHODS: Thirteen OA (64.8 +/- 4.9 yr) exercising 5 
      times per week or more were compared with 14 YA (27.8 +/- 4.9 yr) males and 
      females. IMTG, glycogen, fiber types, succinate dehydrogenase, and 
      capillarization were measured by immunohistochemistry in vastus lateralis 
      biopsies. Fat-ox and carbohydrate (CHO)-ox were measured by indirect calorimetry 
      before and after an insulin clamp and during a cycle ergometer graded maximal 
      test. RESULTS: V O2peak was lower in OA than YA. The OA had greater IMTG in all 
      fiber types and lower glycogen stores than YA. This was reflected in greater 
      proportion of type I and less type II fibers in OA. Type I fibers were similar in 
      size, whereas type II fibers were smaller in OA compared with YA. Both groups had 
      similar succinate dehydrogenase content. Numbers of capillaries per fiber were 
      reduced in OA but with a higher number of capillaries per area. Metabolic 
      flexibility and insulin sensitivity were similar in both groups. Exercise 
      metabolic efficiency was higher in OA. At moderate exercise intensities, 
      carbohydrate-ox was lower in OA but with similar Fat-ox. CONCLUSIONS: Lifelong 
      exercise is associated with higher IMTG content in all muscle fibers and higher 
      metabolic efficiency during exercise that are not explained by differences in 
      muscle fibers types and other muscle characteristics when comparing older with 
      younger athletes matched by exercise mode and frequency.
FAU - Dube, John J
AU  - Dube JJ
AD  - 1Division of Endocrinology and Metabolism, Department of Medicine, School of 
      Medicine, University of Pittsburgh, Pittsburgh, PA; and 2Department of Physiology 
      & Institute of Sport Sciences, School of Biology and Medicine, University of 
      Lausanne, Lausanne, SWITZERLAND.
FAU - Broskey, Nicholas T
AU  - Broskey NT
FAU - Despines, Alex A
AU  - Despines AA
FAU - Stefanovic-Racic, Maja
AU  - Stefanovic-Racic M
FAU - Toledo, Frederico G S
AU  - Toledo FG
FAU - Goodpaster, Bret H
AU  - Goodpaster BH
FAU - Amati, Francesca
AU  - Amati F
LA  - eng
GR  - UL1 TR000005/TR/NCATS NIH HHS/United States
GR  - M01 RR000056/RR/NCRR NIH HHS/United States
GR  - K01-DK-084213-01/DK/NIDDK NIH HHS/United States
GR  - R01-AG20128/AG/NIA NIH HHS/United States
GR  - K01 DK084213/DK/NIDDK NIH HHS/United States
GR  - M01-RR-00056/RR/NCRR NIH HHS/United States
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Med Sci Sports Exerc
JT  - Medicine and science in sports and exercise
JID - 8005433
RN  - 0 (Triglycerides)
RN  - 9005-79-2 (Glycogen)
SB  - IM
MH  - Adolescent
MH  - Adult
MH  - Age Factors
MH  - Aged
MH  - *Athletes
MH  - Carbohydrate Metabolism
MH  - Cross-Sectional Studies
MH  - Exercise/*physiology
MH  - Female
MH  - Glycogen/*metabolism
MH  - Humans
MH  - Insulin Resistance
MH  - Lipid Metabolism
MH  - Male
MH  - Middle Aged
MH  - Muscle Fibers, Fast-Twitch/physiology
MH  - Muscle Fibers, Slow-Twitch/physiology
MH  - Muscle, Skeletal/*anatomy & histology/blood supply/*metabolism
MH  - Oxygen Consumption
MH  - Physical Endurance
MH  - Triglycerides/*metabolism
MH  - Young Adult
PMC - PMC4760922
MID - NIHMS728093
EDAT- 2015/10/16 06:00
MHDA- 2017/01/10 06:00
PMCR- 2017/03/01
CRDT- 2015/10/14 06:00
PHST- 2017/03/01 00:00 [pmc-release]
PHST- 2015/10/14 06:00 [entrez]
PHST- 2015/10/16 06:00 [pubmed]
PHST- 2017/01/10 06:00 [medline]
AID - 10.1249/MSS.0000000000000789 [doi]
PST - ppublish
SO  - Med Sci Sports Exerc. 2016 Mar;48(3):472-80. doi: 10.1249/MSS.0000000000000789.