This study investigated the effects of ingesting a low (LGI) or high (HGI) glyce-mic index carbohydrate (CHO) meal 3 h prior to exercise on endurance running capacity. Eight male recreational runners undertook two trials (LGI or HGI) which were randomized and separated by 7 d. After an overnight fast (12 h) the subjects ingested either a LGI or HGI meal 3 h prior to running at 70% VO2max until exhaustion. The meals contained 2 g/kg body mass CHO and were isocaloric and iso-macronutrient with calculated GI values 77 and 37 for the HGI and LGI respectively. The run times for the LGI and HGI trials were 108.8 ± 4.1 min and 101.4 ± 5.2 min respectively (P = 0.038). Fat oxidation rates were higher during exercise after the LGI meal than after the HGI meal (P < 0.05). In summary, ingestion of a LGI meal 3 h before exercise resulted in a greater endurance capacity than after the ingestion of a HGI meal.
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Ching-Lin Wu and Clyde Williams
Heidi K. Byrne, Yeonsoo Kim, Steven R. Hertzler, Celia A. Watt, and Craig O. Mattern
Purpose:
To compare serum glucose and insulin responses to 3 preexercise snacks before, during, and after exercise in individuals with impaired fasting glucose (IFG) and healthy (H) men. In addition, in an IFG population, the authors sought to determine whether a natural fruit snack (i.e., raisins) yields more desirable glucose and insulin concentrations than an energy bar or a glucose solution.
Methods:
The IFG (n = 11, age = 54.5 ± 1.3 yr, fasting blood glucose [BG] = 6.3 ± 0.1 mmol/L) and H groups (n = 9, age = 48.0 ± 3.1 yr, fasting BG = 4.9 ± 0.1 mmol/L) cycled at 50% of VO2peak for 45 min on 4 occasions after consuming water or 50 g of carbohydrate from raisins (R), an energy bar (EB), or a glucose beverage (GLU). Metabolic markers were measured before, during, and after exercise.
Results:
In all nutritional conditions, glucose concentrations of the IFG group were consistently higher than in the H group. Differences between IFG and H groups in insulin concentrations were sporadic and isolated. In the IFG group, preexercise glucose concentration was lower in the R condition than in GLU. Ten and 20 min into exercise, glucose concentrations in the R and EB conditions were lower than in GLU. Insulin concentrations were lower in the R condition than in EB and GLU immediately before exercise and at Minute 10 but at 20 min R remained lower than only GLU.
Conclusion:
Glucose concentrations were higher in the IFG group regardless of preexercise snack. Compared with the glucose solution, raisins lowered both the postprandial glycemic and insulinemic responses, whereas the energy bar reduced glycemia but not insulinemia.
André O. Werneck, Evelyn C.A. Silva, Maria R.O. Bueno, Lidyane Z. Vignadelli, Adewale L. Oyeyemi, Catiana L.P. Romanzini, Enio R.V. Ronque, and Marcelo Romanzini
and insulinemia ( 6 ), which are also associated with adiposity regulation ( 9 ). Another possible mechanism is through a greater energy expenditure caused by an increased standing time and number of steps ( 7 ), which present a higher energy expenditure than sitting position that could be
Matthew R. Nagy, Molly P. O’Sullivan, Shannon S. Block, Trevor R. Tooley, Leah E. Robinson, Natalie Colabianchi, and Rebecca E. Hasson
directly compared these 2 patterns of activity and determined that regular activity breaks were more effective than continuous physical activity at decreasing postprandial glycemia and insulinemia in healthy, normal-weight adults. McManus et al 25 reported the frequency of activity bouts accumulated per
Vandre C. Figueiredo, Michelle M. Farnfield, Megan L.R. Ross, Petra Gran, Shona L. Halson, Jonathan M. Peake, David Cameron-Smith, and James F. Markworth
expected, ingestion of CHO throughout exercise recovery induced a robust effect on plasma glucose response and insulinemia, as previously reported ( Ross et al., 2010 ). Despite the marked increase in serum glucose and insulin levels, CHO ingestion did not influence the exercise-induced activation of the
Regis C. Pearson, Betsy Cogan, Sara A. Garcia, and Nathan T. Jenkins
on postprandial lipemia and insulinemia in sedentary middle-aged women . Metabolism, 44 ( 3 ), 390 – 397 . https://doi.org/10.1016/0026-0495(95)90172-8 10.1016/0026-0495(95)90172-8 Aldred , H.E. , Perry , I.C. , & Hardman , A.E. ( 1994 ). The effect of a single bout of brisk walking on
outcomes (glycemia, insulinemia, lipids profile and inflammatory cytokines). Results: Intervention enabled to reduce significantly waist to height ratio (-0.01± 0.04, p≤0.05) and improve aerobic fitness during a submaximal exercise (157.3±19.2 vs 153.1±18.5 bpm, p=0.012). INT group improved significantly
