Environmental temperature and glycogen resynthesis

This study investigated the effects of hot (H) and room temperature (RT) recovery environments on glycogen resynthesis. Nine male participants completed two trials, cycling for 1 h in a temperature-controlled chamber (32.6 degrees C), followed by 4 h of recovery at 32.6 degrees C (H) or 22.2 degrees C (RT). Rectal temperature was continuously recorded. A carbohydrate beverage (1.8 g/kg bodyweight) was supplied at 0 and 2 h post-exercise. Muscle biopsies were taken immediately, 2 h, and 4 h post-exercise for glycogen analysis. Blood samples were taken at 30, 60, 120, 150, 180, and 240 min into recovery for glucose and insulin analysis. Expired gas was collected at 105 min and 225 min into recovery to calculate whole body carbohydrate oxidation. Average core temperature, whole body carbohydrate oxidation, and serum glucose at 120, 150, 180 and 240 min was higher in H compared to RT (p<0.05). Muscle glycogen was higher in RT vs. H at 4 h (105+/-28 vs. 88+/-24 mmolxkg (-1) wet weight, respectively; p<0.05), but no different at 0 and 2 h. There was no difference in serum insulin. These data indicate the importance of minimizing the exposure to heat after exercise to improve recovery, specifically to improve glycogen resynthesis.

Glycogen synthesis after road cycling in the fed state

The purpose of this study was to determine the effects of a recovery beverage immediately after exercise on rates of muscle glycogen resynthesis in response to road cycling when nutritional supplementation was supplied during exercise and a solid meal was served two hours after exercise. Eight trained male cyclists, (25+/-4 years, 69.3+/-5.2 kg, VO2 peak=4.5+/-0.4 L.min(-1)) performed two 62 km outdoor training rides in a double-blind, randomized cross-over experiment. Subjects received a food bar and a commercial sport drink during each ride. A recovery beverage (40 g CHO+20 g PRO) or a placebo (PL) was administered 30 min post-exercise. At 2 h post-exercise, a solid meal was provided for both trials. There was no difference between trials at any time point for glycogen (140+/-9, 56+/-8, and 70+/-8 mmol.kg(-1)wet wt.(-1).hr.(-1) for pre, post, and 4 h post, respectively). The addition of a supplemental recovery beverage ingested soon after exercise did not significantly increase the rate of muscle glycogen resynthesis after 4 h of recovery when nutritional supplementation is provided during exercise and a meal is consumed 2 h after exercise.

Glycogen resynthesis and exercise performance with the addition of fenugreek extract (4-hydroxyisoleucine) to post-exercise carbohydrate feeding

The purpose of this study was to determine the effect of adding fenugreek extract (FG) to post-exercise carbohydrate feeding on glycogen resynthesis and subsequent exercise performance in normoglycemic male endurance athletes. A muscle biopsy sample was obtained from the vastus lateralis from subjects prior to exercise for 5 h at 50% of peak cycling power (52.1 +/- 3.3% of VO(2) peak). A second muscle biopsy sample was obtained immediately after exercise. Immediately after and 2 h after the second biopsy subjects ingested either an oral dose of dextrose (GLU) (1.8 g x kg BW(-1)) or GLU with FG containing 1.99 +/- 0.20 mg x kg(-1) 4-hydroxyisoleucine (GLU + FG) in a randomized, cross-over, double blind design. At 4 h post-exercise a third biopsy was taken and subjects received a standardised meal along with FG or a placebo capsule. At 15 h post-exercise subjects underwent their final muscle biopsy before completing a simulated 40 km cycling time trial. There was no difference in muscle glycogen at any time between GLU and GLU + FG. Additionally, 40 km time trial performance was similar for average power output (221 +/- 28 vs. 213 +/- 16 watts) and for time to completion (69.7 +/- 3.7 vs. 70.5 +/- 2.2 min) for the GLU and GLU + FG, respectively. Despite earlier data to the contrary, the present results do not support an effect of fenugreek supplementation on glycogen resynthesis, even though this may have been the result of differences in experimental protocol.

The addition of fenugreek extract (Trigonella foenum-graecum) to glucose feeding increases muscle glycogen resynthesis after exercise

The purpose of this study was to determine the effects of ingesting an oral supplement containing 4-Hydroxyisoleucine (4-OH-Ile, isolated from fenugreek seeds [Trigonella foenum-graecum]) with a glucose beverage on rates of post-exercise muscle glycogen resynthesis in trained male cyclists. Following an overnight fast (12 hr), subjects completed a 90-minute glycogen depletion ride after which a muscle biopsy was obtained from the vastus lateralis. Immediately and 2 hours after the muscle biopsy, subjects ingested either an oral dose of dextrose (Glu) (1.8 g.kg BW(-1)) or 4-OH-Ile supplement (Glu+4-OH-Ile, including 2.0 mg.kg(-1) 4-OH-Ile with the same oral dose of dextrose) with a second muscle biopsy 4 hours after exercise. Post exercise muscle glycogen concentration was similar for both trials. Overall, there was a significant increase in glucose and insulin concentrations from time 0 throughout the majority of the 4-hour recovery period, with no significant differences between the two trials at any time point. Although muscle glycogen concentration significantly increased from immediately post exercise to 4 hr of recovery for both trials, the net rate of muscle glycogen resynthesis was 63% greater during Glu+4-OH-Ile (10.6+/-3.3 vs. 6.5+/-2.6 g.kg wet wt.(-1).hr.(-1) for the Glu+4-OH-Ile and Glu trials, respectively). These data demonstrate that when the fenugreek extract supplement (4-OH-Ile) is added to a high oral dose of dextrose, rates of post-exercise glycogen resynthesis are enhanced above dextrose alone.