Exogenous Oxidation of Isomaltulose Is Lower than That of Sucrose during Exercise in Men

Isomaltulose (ISO) is a disaccharide that is slowly digested, resulting in a slow availability for absorption. The aim of this study was to compare the blood substrate responses and exogenous carbohydrate (CHO) oxidation rates from orally ingested sucrose (SUC) and ISO during moderate intensity exercise. We hypothesized that the oxidation of ISO is lower compared with SUC, resulting in lower plasma glucose and insulin concentrations and subsequent lower CHO and higher fat oxidation rates. Ten trained men [maximal oxygen uptake (VO(2)max), 64 +/- 1 mL/(kg body mass.min)] cycled on 3 occasions for 150 min at 59 +/- 2% VO(2)max and consumed either water (WAT) or 1 of 2 CHO solutions providing 1.1 g/min of CHO in the form of either SUC or ISO. Peak exogenous CHO oxidation rates were higher (P < 0.05) during the SUC trial (0.92 +/- 0.03 g/min) than during the ISO trial (0.54 +/- 0.05 g/min). Total endogenous CHO oxidation over the final 90 min of exercise was lower (P < 0.05) in the SUC trial (107 +/- 10 g) than in the WAT (137 +/- 7 g) and ISO (127 +/- 9 g) trials. Fat oxidation was higher during the WAT trial than during the SUC and ISO trials. ISO resulted in a lower plasma insulin response at 30 min compared with SUC, whereas the glucose response did not differ between the 2 CHO. Oxidation of ingested ISO was significantly less than that of SUC, most likely due to the lower rate of digestion of ISO. A lower CHO delivery and a small difference in plasma insulin may have resulted in higher endogenous CHO use and higher fat oxidation during the ISO trial than during the SUC trial

Postexercise Muscle Glycogen Synthesis with Combined Glucose and Fructose Ingestion

Purpose: To evaluate the efficacy of using combined glucose and fructose (GF) ingestion as a means to stimulate short-term (4 h) postexercise muscle glycogen synthesis compared to glucose only (G). Methods: On two separate occasions, six endurance-trained men performed an exhaustive glycogen-depleting exercise bout followed by a 4-h recovery period. Muscle biopsy samples were obtained from the vastus lateralis muscle at 0, 1, and 4 h after exercise. Subjects ingested carbohydrate solutions containing G (90 gIhj1) or GF (G = 60 gIhj1; F = 30 gIhj1) commencing immediately after exercise and every 30 min thereafter. Results: Immediate postexercise muscle glycogen concentrations were similar in both trials (G = 128 T 25 mmolIkgj1 dry muscle (dm) vs GF = 112 T 16 mmolIkgj1 dm; P 9 0.05). Total glycogen storage during the 4-h recovery period was 176 T 33 and 155 T 31 mmolIkgj1 dm for G and GF, respectively (G vs GF, P 9 0.05). Hence, mean muscle glycogen synthesis rates during the 4-h recovery period did not differ between the two conditions (G = 44 T 8 mmolIkgj1 dmIhj1 vs GF = 39 T 8 mmolIkgj1 dmIhj1, P 9 0.05). Plasma glucose and serum insulin responses during the recovery period were similar in both conditions, although plasma lactate concentrations were significantly elevated during GF compared to G (by È0.8 mmolILj1, P G 0.05). Conclusions: Glucose and glucose/fructose (2:1 ratio) solutions, ingested at a rate of 90 gIhj1, are equally effective at restoring muscle glycogen in exercised muscles during the recovery from exhaustive exercise

Effects of carbohydrates-BCAAs-caffeine ingestion on performance and neuromuscular function during a 2-h treadmill run: a randomized, double-blind, cross-over placebo-controlled study

<p>Abstract</p> <p>Background</p> <p>Carbohydrates (CHOs), branched-chain amino acids (BCAAs) and caffeine are known to improve running performance. However, no information is available on the effects of a combination of these ingredients on performance and neuromuscular function during running.</p> <p>Methods</p> <p>The present study was designed as a randomized double-blind cross-over placebo-controlled trial. Thirteen trained adult males completed two protocols, each including two conditions: placebo (PLA) and Sports Drink (SPD: CHOs 68.6 g.L^-1, BCAAs 4 g.L^-1, caffeine 75 mg.L^-1). Protocol 1 consisted of an all-out 2 h treadmill run. Total distance run and glycemia were measured. In protocol 2, subjects exercised for 2 h at 95% of their lowest average speeds recorded during protocol 1 (whatever the condition). Glycemia, blood lactate concentration and neuromuscular function were determined immediately before and after exercise. Oxygen consumption (<inline-formula><m:math xmlns:m="http://www.w3.org/1998/Math/MathML" name="1550-2783-8-22-i1"><m:mover accent="true"><m:mrow><m:mstyle class="text"><m:mtext class="textsf" mathvariant="sans-serif">V</m:mtext></m:mstyle></m:mrow><m:mo class="MathClass-op">˙</m:mo></m:mover><m:msub><m:mrow><m:mstyle class="text"><m:mtext class="textsf" mathvariant="sans-serif">O</m:mtext></m:mstyle></m:mrow><m:mrow><m:mn>2</m:mn></m:mrow></m:msub></m:math></inline-formula>), heart rate (HR) and rate of perceived exertion (RPE) were recorded during the exercise. Total fluids ingested were 2 L whatever the protocols and conditions.</p> <p>Results</p> <p>Compared to PLA, ingestion of SPD increased running performance (p = 0.01), maintained glycemia and attenuated central fatigue (p = 0.04), an index of peripheral fatigue (p = 0.04) and RPE (p = 0.006). Maximal voluntary contraction, <inline-formula><m:math xmlns:m="http://www.w3.org/1998/Math/MathML" name="1550-2783-8-22-i1"><m:mover accent="true"><m:mrow><m:mstyle class="text"><m:mtext class="textsf" mathvariant="sans-serif">V</m:mtext></m:mstyle></m:mrow><m:mo class="MathClass-op">˙</m:mo></m:mover><m:msub><m:mrow><m:mstyle class="text"><m:mtext class="textsf" mathvariant="sans-serif">O</m:mtext></m:mstyle></m:mrow><m:mrow><m:mn>2</m:mn></m:mrow></m:msub></m:math></inline-formula>, and HR did not differ between the two conditions.</p> <p>Conclusions</p> <p>This study showed that ingestion of a combination of CHOs, BCAAs and caffeine increased performance by about 2% during a 2-h treadmill run. The results of neuromuscular function were contrasted: no clear cut effects of SPD were observed.</p> <p>Trial registration</p> <p>ClinicalTrials.gov, <url>http://www.clinicaltrials.gov</url>, <a href="http://www.clinicaltrials.gov/ct2/show/NCT00799630">NCT00799630</a></p