High muscle glycogen content improves an athlete’s work capacity.
Muscle glycogen appears to provide feedback to the central nervous system, acting as a type of regulator, with higher muscle glycogen content resulting in athletes’ self-selection of higher paces in both cycling time trials and intermittent-sprint exercise. The researchers who discovered this effect of glycogen named it the “glycostat.” The original research on this concept was performed on cyclists during a time trial in which they did not receive feedback regarding their power, distance, speed or heart rate. Thus, the cyclists had to self-select a pace. The cyclists selected a higher pace when they started the time trial with higher glycogen content levels. 1
In their research paper, the scientists hypothesized that the improvement in pacing strategies during the carbohydrate loaded time trial “may have resulted from integrated feedback from the periphery, perhaps from glycogen content in exercising muscles.” 1 Follow-up research has been performed in intermittent-sprint athletes. The total distance and hard running distance were 4.9 and 8.1 percent greater when the runners commenced exercise with high muscle glycogen content levels. The abstract for this paper states, “These results indicate HCHO (high carbohydrate) improved self-paced exercise intensities during the ISE (intermittent sprint exercise) protocol despite no knowledge of dietary manipulation. Due to the blinded study design, exercise intensities seem manipulated due to peripheral perturbations associated with CHO (carbohydrate) content rather than a conscious manipulation of exercise intensities.”2
Although the “glycostat” idea was not postulated until 2003, earlier studies in soccer and hockey produced similar results. In the hockey study, which investigated performance in relation to muscle glycogen concentration, researchers found that the distance skated, number of shifts skated, amount of time skated within shifts and skating speed all improved when athletes started their performance with higher muscle glycogen content. 3 Additionally, in the soccer study, researchers determined that “the amount of high intensity exercise, defined as the total amount of moderate to high speed running and sprinting, performed during a small-sided game of football (soccer) was (positively) influenced by pre-exercise muscle glycogen concentration.” 4
Based on the results of these research studies, athletic preparation programs for both endurance time trials and intermittent sprint sports should include ensuring that athletes begin important training and competitions with high muscle glycogen content levels to promote optimal athletic performance. MuscleSound can determine athletes’ muscle glycogen content levels quickly, precisely and noninvasively using patented technology and software to optimize athletic preparedness.
 A Rauch HG, St Clair Gibson A, Lambert EV, Noakes TD. A signaling role for muscle glycogen in the regulation of pace during prolonged exercise. Br J Sports Med. 2005 Jan;39(1):34-8. PubMed PMID: 15618337; PubMed Central PMCID: PMC1725021.
 Skein M, Duffield R, Kelly BT, Marino FE. The effects of carbohydrate intake and muscle glycogen content on self-paced intermittent-sprint exercise despite no knowledge of carbohydrate manipulation. Eur J Appl Physiol. 2012 Aug;112(8):2859-70. doi: 10.1007/s00421-011-2253-0. Epub 2011 Dec
 PubMed PMID:22138866.3. Akermark C, Jacobs I, Rasmusson M, Karlsson J: Diet and muscle glycogen concentration in relation to physical performance in Swedish elite ice hockey players. Int J Sport Nutr. 1996 Sep;6(3):272-84.
 Balsom PD, Wood K, Olsson P, Ekblom B: Carbohydrate intake and multiple sprint sports: with special reference to football (soccer). Int J Sports Med 1999; 20: 48-52.