1.
Effect of protein and carbohydrate solutions on running performance and cognitive function in female recreational runners.
Gui, Z, Sun, F, Si, G, Chen, Y
PloS one. 2017;12(10):e0185982
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Plain language summary
Research has shown that consuming a carbohydrate-electrolyte solution (CES) during endurance exercise can improve performance, delay fatigue and ameliorate post-exercise cognitive dysfuction when compared with a noncaloric placebo (PLA). The addition of protein to the CES (CPES) has been suggested to increase these benefits however the current data is limited. The aim of this crossover study was to investigate whether the added protein to a CES would improve exercise performance and cognitive function in 11 female recreational marathon runners. Participants were randomised to consume one of the three solutions (CES, CPES or PLA) every 2.5km during a 21km run, with a 28-day interval, and their VO2max and cognitive function were recorded after the run. This study showed that CES improved endurance performance compared with PLA, however adding protein to the CES did not provide any additional performance benefit. The CPES solution did benefit visual motor speed compared to PLA, but no differences were found in the other cognitive function tests.
Abstract
This study compared the effects of a carbohydrate-electrolyte-protein solution (CEPS, 2% protein plus 4% carbohydrate), carbohydrate-electrolyte solution (CES, 6% carbohydrate), and noncaloric sweetened placebo (PLA) on both 21-km running performance and cognitive function. Eleven female recreational endurance runners performed a 21-km time-trial running on three occasions, separated by at least 28 days. In a randomized cross-over design, they ingested CEPS, CES, or PLA at a rate of 150 mL every 2.5 km with no time feedback. A cognitive function test was performed before and after the run. Participants ingested approximately 24 g/h carbohydrate plus 12 g/h protein in CEPS trial, and 36 g/h carbohydrate in CES trial during each 21-km trial. Time to complete the time-trial was slightly shorter (P < 0.05) during CES (129.6 ± 8.8 min) than PLA (134.6 ± 11.5 min), with no differences between CEPS and the other two trials. The CEPS trial showed higher composite of visual motor speed than the PLA trial (P < 0.05). In conclusion, CES feedings might improve 21-km time-trial performance in female recreational runners compared with a PLA. However, adding protein to the CES provided no additional time-trial performance benefit. CEPS feeding during prolonged exercise could benefit visual motor speed compared to PLA alone, but no differences in the performance of the other cognitive function tests were found.
2.
Use of Novel High-Protein Functional Food Products as Part of a Calorie-Restricted Diet to Reduce Insulin Resistance and Increase Lean Body Mass in Adults: A Randomized Controlled Trial.
Johnston, CS, Sears, B, Perry, M, Knurick, JR
Nutrients. 2017;9(11)
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Reducing insulin resistance (IR) is achieved by either calorie restriction or increase of lean muscle mass, however calorie restriction tends to lead to a decrease of lean mass. The aim of this trial was to determine whether the protein content of a low-calorie diet impacted insulin resistance levels. Twenty-one healthy adults at risk of IR were randomly assigned to receive either high-protein diet or conventional diet food packages, both of which had the same calorie restriction. Weight and blood samples were collected at baseline and six weeks. This study found that an increased protein consumption with moderate calorie restriction was 140% more effective for reducing IR compared to a conventional, isocaloric diet. While significant weight loss occurred in both groups, the reduction in IR was significantly associated only with the increase of lean mass. These results justify future long-term studies focusing on the combination of various dietary strategies to reduce IR and increase lean mass.
Abstract
Significant reductions in insulin resistance (IR) can be achieved by either calorie restriction or by the increase of lean mass. However, calorie restriction usually results in significant loss of lean mass. A 6-week randomized controlled feeding trial was conducted to determine if a calorie-restricted, high-protein diet (~125 g protein/day consumed evenly throughout the day) using novel functional foods would be more successful for reducing IR in comparison to a conventional diet (~80 g protein/day) with a similar level of calorie restriction. Healthy adults (age 20-75 years; body mass index, 20-42 kg/m²) with raised triglyceride/high-density lipoprotein ratios were randomly assigned to the control group (CON: test foods prepared using gluten-free commercial pasta and cereal) or to the high-protein group (HPR: test foods prepared using novel high-protein pasta and cereal both rich in wheat gluten). Mean weight loss did not differ between groups (-2.7 ± 2.6 and -3.2 ± 3.0 kg for CON (n = 11) and HPR (n = 10) respectively, p = 0.801); however, the 6-week change in fat-free mass (FFM) differed significantly between groups (-0.5 ± 1.5 and +1.5 ± 3.8 kg for CON and HPR respectively, p = 0.008). IR improved in HPR vs. CON participants (homeostasis model assessment-estimated insulin resistance [HOMAIR] change: -1.7 ± 1.4 and -0.7 ± 0.7 respectively; p = 0.020). The change in HOMA-IR was related to the change in FFM among participants (r = -0.511, p = 0.021). Thus, a high-protein diet using novel functional foods combined with modest calorie restriction was 140% more effective for reducing HOMA-IR in healthy adults compared to a lower protein, standard diet with an equal level of calorie restriction.