TY - JOUR
T1 - Relationship between muscle water and glycogen recovery after prolonged exercise in the heat in humans
AU - Fernández-Elías, Valentín E.
AU - Ortega, Juan F.
AU - Nelson, Rachael K.
AU - Mora-Rodriguez, Ricardo
N1 - Funding Information:
We truly thank the participants for their dedication and effort. We thank Rafael Urrialde health and nutrition director from Coca Cola Iberia for the gracious donation of the carbohydrate powder (Powerade). We thank Dr. Jeffrey F. Horowitz from the University of Michigan for his advice and guidance during pilot data collection. V.E.F-E. was supported by a predoctoral fellowship from the Junta de Comunidades de Castilla-La Mancha. This study was partially supported by a grant from the Junta de Comunidades de Castilla-La Mancha (PEII-2014-004-A). ®
Publisher Copyright:
© 2015, Springer-Verlag Berlin Heidelberg.
PY - 2015/9/17
Y1 - 2015/9/17
N2 - Purpose: It is usually stated that glycogen is stored in human muscle bound to water in a proportion of 1:3 g. We investigated this proportion in biopsy samples during recovery from prolonged exercise. Methods: On two occasions, nine aerobically trained subjects (V˙O2max = 54.4 ± 1.05 mL kg−1 min−1; mean ± SD) dehydrated 4.6 ± 0.2 % by cycling 150 min at 65 % V˙O2max in a hot-dry environment (33 ± 4 °C). One hour after exercise subjects ingested 250 g of carbohydrates in 400 mL of water (REHLOW) or the same syrup plus water to match fluid losses (i.e., 3170 ± 190 mL; REHFULL). Muscle biopsies were obtained before, 1 and 4 h after exercise. Results: In both trials muscle water decreased from pre-exercise similarly by 13 ± 6 % and muscle glycogen by 44 ± 10 % (P < 0.05). After recovery, glycogen levels were similar in both trials (79 ± 15 and 87 ± 18 g kg−1 dry muscle; P = 0.20) while muscle water content was higher in REHFULL than in REHLOW (3814 ± 222 vs. 3459 ± 324 g kg−1 dm, respectively; P < 0.05; ES = 1.06). Despite the insufficient water provided during REHLOW, per each gram of glycogen, 3 g of water was stored in muscle (recovery ratio 1:3) while during REHFULL this ratio was higher (1:17). Conclusions: Our findings agree with the long held notion that each gram of glycogen is stored in human muscle with at least 3 g of water. Higher ratios are possible (e.g., during REHFULL) likely due to water storage not bound to glycogen.
AB - Purpose: It is usually stated that glycogen is stored in human muscle bound to water in a proportion of 1:3 g. We investigated this proportion in biopsy samples during recovery from prolonged exercise. Methods: On two occasions, nine aerobically trained subjects (V˙O2max = 54.4 ± 1.05 mL kg−1 min−1; mean ± SD) dehydrated 4.6 ± 0.2 % by cycling 150 min at 65 % V˙O2max in a hot-dry environment (33 ± 4 °C). One hour after exercise subjects ingested 250 g of carbohydrates in 400 mL of water (REHLOW) or the same syrup plus water to match fluid losses (i.e., 3170 ± 190 mL; REHFULL). Muscle biopsies were obtained before, 1 and 4 h after exercise. Results: In both trials muscle water decreased from pre-exercise similarly by 13 ± 6 % and muscle glycogen by 44 ± 10 % (P < 0.05). After recovery, glycogen levels were similar in both trials (79 ± 15 and 87 ± 18 g kg−1 dry muscle; P = 0.20) while muscle water content was higher in REHFULL than in REHLOW (3814 ± 222 vs. 3459 ± 324 g kg−1 dm, respectively; P < 0.05; ES = 1.06). Despite the insufficient water provided during REHLOW, per each gram of glycogen, 3 g of water was stored in muscle (recovery ratio 1:3) while during REHFULL this ratio was higher (1:17). Conclusions: Our findings agree with the long held notion that each gram of glycogen is stored in human muscle with at least 3 g of water. Higher ratios are possible (e.g., during REHFULL) likely due to water storage not bound to glycogen.
KW - Carbohydrates
KW - Muscle glycogen storage
KW - Muscle water
KW - Oral rehydration
KW - Sweating
UR - http://www.scopus.com/inward/record.url?scp=84939263297&partnerID=8YFLogxK
U2 - 10.1007/s00421-015-3175-z
DO - 10.1007/s00421-015-3175-z
M3 - Article
C2 - 25911631
AN - SCOPUS:84939263297
VL - 115
SP - 1919
EP - 1926
JO - European Journal of Applied Physiology
JF - European Journal of Applied Physiology
SN - 1439-6319
IS - 9
ER -