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Metabolic, hormonal and performance effects of isomaltulose ingestion before prolonged aerobic exercise: a double-blind, randomised, cross-over trial.
Notbohm, HL, Feuerbacher, JF, Papendorf, F, Friese, N, Jacobs, MW, Predel, HG, Zacher, J, Bloch, W, Schumann, M
Journal of the International Society of Sports Nutrition. 2021;18(1):38
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Isomaltulose is a low-glycaemic index carbohydrate that lowers insulin and glucose levels postprandially. The benefits of taking Isomaltulose in an exercise setting are not well studied. This double-blinded, randomised, crossover study evaluated the effects of Isomaltulose intake on metabolic responses, hormonal responses, exercise performance and gastrointestinal disturbances in runners. Twenty-one male recreational endurance runners took part in four separate experimental sessions to compare Isomaltulose to maltodextrin and glucose. Fat and carbohydrate oxidation rates were not different among groups. This might be because the lower dose of Isomaltulose (50g) was used in this trial. Compared to glucose and maltodextrin, isomaltulose lowered metabolic and hormonal responses to exercise. In the study, Isomaltulose, glucose, and maltodextrin did not differ in exercise performance or gastrointestinal disturbances. A higher dose may be needed in order to demonstrate exercise performance, but caution should be exercised since a higher dose may cause gastrointestinal upset. A robust investigation of Isomalulose dose and its effects on glucose, insulin, and glucose-dependent insulinotropic polypeptides is required to determine if exercise leads to hypoglycaemia in the clinical population. Healthcare practitioners can use the findings of this study to understand the advantageous effects of 50g Isomaltulose in regulating glucose, insulin and glucose-dependent insulinotropic polypeptide during aerobic exercise.
Abstract
BACKGROUND Isomaltulose has been discussed as a low glycaemic carbohydrate but evidence concerning performance benefits and physiological responses has produced varying results. Therefore, we primarily aimed to investigate the effects of isomaltulose ingestion compared to glucose and maltodextrin on fat and carbohydrate oxidation rates, blood glucose levels and serum hormone concentrations of insulin and glucose-dependent insulinotropic polypeptide (GIP). As secondary aims, we assessed running performance and gastrointestinal discomfort. METHODS Twenty-one male recreational endurance runners performed a 70-min constant load trial at 70% maximal running speed (Vmax), followed by a time to exhaustion (TTE) test at 85% Vmax after ingesting either 50 g isomaltulose, maltodextrin or glucose. Fat and carbohydrate oxidation rates were calculated from spiroergometric data. Venous blood samples for measurement of GIP and insulin were drawn before, after the constant load trial and after the TTE. Capillary blood samples for glucose concentrations and subjective feeling of gastrointestinal discomfort were collected every 10 min during the constant load trial. RESULTS No between-condition differences were observed in the area under the curve analysis of fat (p = 0.576) and carbohydrate oxidation rates (p = 0.887). Isomaltulose ingestion led to lower baseline postprandial concentrations of blood glucose compared to maltodextrin (percent change [95% confidence interval], - 16.7% [- 21.8,-11.6], p < 0.001) and glucose (- 11.5% [- 17.3,-5.7], p = 0.001). Similarly, insulin and GIP concentrations were also lower following isomaltulose ingestion compared to maltodextrin (- 40.3% [- 50.5,-30.0], p = 0.001 and - 69.1% [- 74.3,-63.8], p < 0.001, respectively) and glucose (- 32.6% [- 43.9,-21.2], p = 0.012 and - 55.8% [- 70.7,-40.9], p < 0.001, respectively). Furthermore, glucose fluctuation was lower after isomaltulose ingestion compared to maltodextrin (- 26.0% [- 34.2,-17.8], p < 0.001) and glucose (- 17.4% [- 29.1,-5.6], p < 0.001). However, during and after exercise, no between-condition differences for glucose (p = 0.872), insulin (p = 0.503) and GIP (p = 0.244) were observed. No between-condition differences were found for TTE (p = 0.876) or gastrointestinal discomfort (p = 0.119). CONCLUSION Isomaltulose ingestion led to lower baseline postprandial concentrations of glucose, insulin and GIP compared to maltodextrin and glucose. Consequently, blood glucose fluctuations were lower during treadmill running after isomaltulose ingestion, while no between-condition differences were observed for CHO and fat oxidation rates, treadmill running performance and gastrointestinal discomfort. Further research is required to provide specific guidelines on supplementing isomaltulose in performance and health settings.
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Is a vegan diet detrimental to endurance and muscle strength?
Boutros, GH, Landry-Duval, MA, Garzon, M, Karelis, AD
European journal of clinical nutrition. 2020;74(11):1550-1555
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There is a common belief amongst the general population that a vegan diet leads to lower exercise performance due to the potential lack of dietary protein and nutrients. However, previous research that compared aerobic capacity and muscle strength between different diet groups only showed marginal variance, if any at all. But it is criticized that these studies did not always distinguish between the multiple subtypes of vegetarian or veganism. Hence this study sought to focus specifically on the comparison of strict plant-based eaters with omnivores. The participants involved were 56 active women, around their mid-twenties, with an average Body Mass Index of 22. Assessed were estimated VO2 max (an indicator of aerobic fitness), submaximal endurance performance and upper and lower body muscle strength. The 3-day food diaries of each participant was analysed and showed a similar intake of energy and fats in both groups. Vegans had higher carbohydrate, fibre, vitamin C, iron, and magnesium consumption and lower intake of protein, leucine, alanine, saturated fat, vitamin D, and vitamin B12, when compared to omnivores. Whilst upper body strength appeared to be marginally lower in the vegan group, higher levels of estimated VO2 max and significantly higher submaximal endurance levels were observed. The results contradict the common belief, demonstrating that a vegan diet appears to have no detrimental impact on endurance and muscle strength in healthy, young and lean women. In fact, the findings suggest that a vegan diet can be advantageous on endurance performance compared to omnivores. The authors propose that the higher intake of carbohydrates amongst vegans could be linked to better endurance performance and that such a plant-based diet can have favourable effects on oxidative stress and inflammatory profiles. The outcomes of this study may be of interest to those supporting the sports performance of strict plant-based eaters.
Abstract
BACKGROUND/OBJECTIVES In the general population, there is a popular belief that a vegan diet may be associated with a lower exercise performance due to the lack of certain nutrients in vegan individuals. Thus, the purpose of the present study was to examine endurance and muscle strength differences between vegan and omnivore participants. SUBJECTS/METHODS We studied 56 healthy young lean physically active women (age: 25.6 ± 4.1 years; body mass index: 22 ± 1.9 kg/m2). Participants were classified as vegan (n = 28) or omnivore (n = 28) based on their eating habits. All volunteers followed either a vegan or an omnivore diet for at least 2 years. Anthropometric measurements, body composition, estimated maximal oxygen consumption (VO2 max), a submaximal endurance test (70% of VO2 max), muscle strength (leg and chest press), and dietary factors were measured. RESULTS Both groups were comparable for physical activity levels, body mass index, percent body fat, lean body mass, and muscle strength. However, vegans had a significantly higher estimated VO2 max (44.5 ± 5.2 vs. 41.6 ± 4.6 ml/kg/min; p = 0.03, respectively) and submaximal endurance time to exhaustion (12.2 ± 5.7 vs. 8.8 ± 3.0 min; p = 0.007, respectively) compared with omnivores. CONCLUSIONS The results suggest that a vegan diet does not seem to be detrimental to endurance and muscle strength in healthy young lean women. In fact, our study showed that submaximal endurance might be better in vegans compared with omnivores. Therefore, these findings contradict the popular belief of the general population.
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Effects of Low Versus Moderate Glycemic Index Diets on Aerobic Capacity in Endurance Runners: Three-Week Randomized Controlled Crossover Trial.
Durkalec-Michalski, K, Zawieja, EE, Zawieja, BE, Jurkowska, D, Buchowski, MS, Jeszka, J
Nutrients. 2018;10(3)
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During athletic performance, adequate amounts of carbohydrates are required to prolong the onset of fatigue. Research on whether the glycaemic index (GI) of ingested carbohydrates effects performance has been explored but has produced equivocal results. The aim of this randomised crossover study was to assess the effect of low- and moderate- GI diets on the aerobic capacity and endurance performance in 21 runners. Participants consumed a low- and moderate- GI, high carbohydrate and nutrient balanced diets for three weeks each with a two-week washout period. Aerobic capacity and body composition were measured at the beginning and end of each diet period through various athletic performance tests. This study found that after a low-GI, high-carbohydrate diet, improvements were seen in time to exhaustion and running performance. Gas exchange was improved by both diets. The low-GI carbohydrate diet helped athletes to maintain a more stable blood glucose concentration during exertion tests. Based on these results the authors suggest considering GI when planning a diet for performance athletes, and also urge further research be completed to better understand the effects of long-term GI diets with regards to exercise performance.
Abstract
The glycemic index (GI) of ingested carbohydrates may influence substrate oxidation during exercise and athletic performance. Therefore, the aim of this study was to assess the effect of low- and moderate-GI three-week diets on aerobic capacity and endurance performance in runners. We conducted a randomized crossover feeding study of matched diets differing only in GI (low vs. moderate) in 21 endurance-trained runners. Each participant consumed both, low- (LGI) and moderate-GI (MGI) high-carbohydrate (~60%) and nutrient-balanced diets for three weeks each. At the beginning and end of each diet, participants had their aerobic capacity and body composition measured and performed a 12-min running test. After LGI, time to exhaustion during incremental cycling test (ICT) and distance covered in the 12-min run were significantly increased. The MGI diet led to an increase in maximal oxygen uptake ( V ˙ O₂max), but no performance benefits were found after the MGI diet. The LGI and MGI diets improved time and workload at gas exchange threshold (GET) during ICT. The results indicate that a three-week high-carbohydrate LGI diet resulted in a small but significant improvement in athletic performance in endurance runners. Observed increase in V ˙ O₂max on MGI diet did not affect performance.