TY - JOUR
T1 - Effects of carbohydrate supplementation and carbohydrate oxidation following intensified cycle training
AU - Halson, Shona
AU - Lancaster, G
AU - Achten, Juul
AU - Gleeson, Michael
AU - Jeukendrup, Asker
PY - 2004/5/14
Y1 - 2004/5/14
N2 - To study the effects of carbohydrate (CHO) supplementation on performance changes and symptoms of overreaching, six male endurance cyclists completed 1 wk of normal (N), 8 days of intensified (ITP), and 2 wk of recovery training (R) on two occasions in a randomized crossover design. Subjects completed one trial with a 6% CHO solution provided before and during training and a 20% solution in the 1 h postexercise (H-CHO trial). On the other occasion, Subjects consumed a 2% CHO solution at the same time points (L-CHO). A significant decline in time to fatigue at similar to63% maximal power Output (H-CHO: 17+/-3%; L-CHO: 26+/-7%) and a significant increase in mood disturbance occurred in both trials after ITP. The decline in performance was significantly greater in the L-CHO trial. After ITP, a significant decrease in estimated muscle glycogen oxidation (H-CHO: N 49.3+/-2.9 kcal/30 min, ITP 32.6+/-3.4 kcal/30 min; L-CHO: N 49.1+/-30 kcal/30 min, ITP 39.0+/-5.6 kcal/30 min) and increase in fat oxidation (H-CHO: N 16.3+/-2.4 kcal/30 min, ITP 27.8+/-2.3 kcal/30 min; L-CHO: N 16.9+/-2.6 kcal/30 min, ITP: 25.4+/-3.5 kcal/30 min) occurred alongside significant increases in glycerol and free fatty acids and decreases in free triglycerides in both trials. An interaction effect was observed for submaximal plasma concentrations of cortisol and epinephrine, with significantly greater reductions in these stress hormones in L-CHO compared with H-CHO after ITP. These findings suggest that CHO supplementation can reduce the symptoms of overreaching but cannot prevent its development. Decreased endocrine responsiveness to exercise may be implicated in the decreased performance and increased mood disturbance characteristic of overreaching.
AB - To study the effects of carbohydrate (CHO) supplementation on performance changes and symptoms of overreaching, six male endurance cyclists completed 1 wk of normal (N), 8 days of intensified (ITP), and 2 wk of recovery training (R) on two occasions in a randomized crossover design. Subjects completed one trial with a 6% CHO solution provided before and during training and a 20% solution in the 1 h postexercise (H-CHO trial). On the other occasion, Subjects consumed a 2% CHO solution at the same time points (L-CHO). A significant decline in time to fatigue at similar to63% maximal power Output (H-CHO: 17+/-3%; L-CHO: 26+/-7%) and a significant increase in mood disturbance occurred in both trials after ITP. The decline in performance was significantly greater in the L-CHO trial. After ITP, a significant decrease in estimated muscle glycogen oxidation (H-CHO: N 49.3+/-2.9 kcal/30 min, ITP 32.6+/-3.4 kcal/30 min; L-CHO: N 49.1+/-30 kcal/30 min, ITP 39.0+/-5.6 kcal/30 min) and increase in fat oxidation (H-CHO: N 16.3+/-2.4 kcal/30 min, ITP 27.8+/-2.3 kcal/30 min; L-CHO: N 16.9+/-2.6 kcal/30 min, ITP: 25.4+/-3.5 kcal/30 min) occurred alongside significant increases in glycerol and free fatty acids and decreases in free triglycerides in both trials. An interaction effect was observed for submaximal plasma concentrations of cortisol and epinephrine, with significantly greater reductions in these stress hormones in L-CHO compared with H-CHO after ITP. These findings suggest that CHO supplementation can reduce the symptoms of overreaching but cannot prevent its development. Decreased endocrine responsiveness to exercise may be implicated in the decreased performance and increased mood disturbance characteristic of overreaching.
KW - overreaching
KW - metabolism
KW - stable isotope
UR - http://www.scopus.com/inward/record.url?scp=4644309910&partnerID=8YFLogxK
U2 - 10.1152/japplphysiol.01368.2003
DO - 10.1152/japplphysiol.01368.2003
M3 - Article
C2 - 15155717
SN - 1522-1601
VL - 97
SP - 1245
EP - 1253
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 4
ER -