PMID- 24091991
OWN - NLM
STAT- MEDLINE
DCOM- 20141021
LR  - 20181202
IS  - 1530-0315 (Electronic)
IS  - 0195-9131 (Linking)
VI  - 46
IP  - 3
DP  - 2014 Mar
TI  - Muscle glycogen content modifies SR Ca2+ release rate in elite endurance 
      athletes.
PG  - 496-505
LID - 10.1249/MSS.0000000000000132 [doi]
AB  - PURPOSE: The aim of the present study was to investigate the influence of muscle 
      glycogen content on sarcoplasmic reticulum (SR) function and peak power output 
      (Wpeak) in elite endurance athletes. METHODS: Fourteen highly trained male 
      triathletes (VO2max = 66.5 +/- 1.3 mL O2.kg.min), performed 4 h of 
      glycogen-depleting cycling exercise (HRmean = 73% +/- 1% of maximum). During the 
      first 4 h of recovery, athletes received either water (H2O) or carbohydrate 
      (CHO), separating alterations in muscle glycogen content from acute changes 
      affecting SR function and performance. Thereafter, all subjects received 
      CHO-enriched food for the remaining 20-h recovery period. RESULTS: Immediately 
      after exercise, muscle glycogen content and SR Ca release rate was reduced to 32% 
      +/- 4% (225 +/- 28 mmol.kg dw) and 86% +/- 2% of initial levels, respectively (P < 
      0.01). Glycogen markedly recovered after 4 h of recovery with CHO (61% +/- 2% of 
      preexercise) and SR Ca release rate returned to preexercise level. However, in 
      the absence of CHO during the first 4 h of recovery, glycogen and SR Ca release 
      rate remained depressed, with the normalization of both parameters at the end of 
      the 24 h of recovery after receiving a CHO-enriched diet. Linear regression 
      demonstrated a significant correlation between SR Ca release rate and muscle 
      glycogen content (P < 0.01, r = 0.30). The 4 h of cycling exercise reduced Wpeak 
      by 5.5%-8.9% at different cadences (P < 0.05), and Wpeak was normalized after 4 h 
      of recovery with CHO, whereas Wpeak remained depressed (P < 0.05) after water 
      provision. Wpeak was fully recovered after 24 h in both the H2O and the CHO 
      group. CONCLUSION: In conclusion, the present results suggest that low muscle 
      glycogen depresses muscle SR Ca release rate, which may contribute to fatigue and 
      delayed recovery of Wpeak 4 h postexercise.
FAU - Gejl, Kasper Degn
AU  - Gejl KD
AD  - 1Institute of Sports Science and Clinical Biomechanics, SDU Muscle Research 
      Cluster (SMRC), University of Southern Denmark, Odense, DENMARK; 2Swedish Winter 
      Sports Research Centre, Department of Health Sciences, Mid Sweden University, 
      Ostersund, SWEDEN; and 3The Astrand Laboratory, Swedish School of Sport and 
      Health Sciences, Stockholm, SWEDEN.
FAU - Hvid, Lars Grondahl
AU  - Hvid LG
FAU - Frandsen, Ulrik
AU  - Frandsen U
FAU - Jensen, Kurt
AU  - Jensen K
FAU - Sahlin, Kent
AU  - Sahlin K
FAU - Ortenblad, Niels
AU  - Ortenblad N
LA  - eng
PT  - Journal Article
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  - 33X04XA5AT (Lactic Acid)
RN  - 9005-79-2 (Glycogen)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Adult
MH  - *Athletes
MH  - Bicycling/physiology
MH  - Calcium/*metabolism
MH  - Denmark
MH  - Glycogen/*metabolism
MH  - Humans
MH  - Ion Transport/*drug effects
MH  - Lactic Acid/blood
MH  - Male
MH  - Muscle, Skeletal/*metabolism
MH  - Oxygen Consumption/physiology
MH  - Physical Fitness/physiology
MH  - Sarcoplasmic Reticulum/*metabolism
EDAT- 2013/10/05 06:00
MHDA- 2014/10/22 06:00
CRDT- 2013/10/05 06:00
PHST- 2013/10/05 06:00 [entrez]
PHST- 2013/10/05 06:00 [pubmed]
PHST- 2014/10/22 06:00 [medline]
AID - 10.1249/MSS.0000000000000132 [doi]
PST - ppublish
SO  - Med Sci Sports Exerc. 2014 Mar;46(3):496-505. doi: 10.1249/MSS.0000000000000132.