The metabolic responses to high carbohydrate meals with different glycemic indices consumed during recovery from prolonged strenuous exercise

This study investigated the metabolic responses to high glycemic index (HGI) or low glycemic index (LGI) meals consumed during recovery from prolonged exercise. 8 trained male athletes undertook 2 trials. Following an overnight fast, subjects completed a 90 minute run. Meals were provided 30 minutes and 2 hours following cessation of exercise. The plasma glucose responses to both meals were greater in the HGI trial compared to the LGI trial. Following breakfast, there were no differences in the serum insulin concentrations between the trials; however, following lunch, concentrations were higher in the HGI trial compared to the LGI trial. This suggests that the glycemic index of the carbohydrates consumed during the immediate post-exercise period might not be important as long as sufficient carbohydrate is consumed. The high insulin concentrations following a HGI meal later in the recovery period could facilitate further muscle glycogen resynthesis

The effect of exercise on plasma soluble IL-6 receptor concentration: a dichotomous response

The aim of this article is to review current literature on the response of soluble interleukin-6 receptor to exercise and identify a potential role for sIL-6R in skeletal muscle function. We also provide novel data on the impact of eccentric exercise on circulating levels. The aim of the research study was to investigate changes in plasma concentration of soluble interleukin-6 receptor (sIL-6R) and soluble glycoprotein 130 (sgp130) during recovery from exercise-induced muscle damage (EIMD) up to 72 h and their relationship with delayed onset muscle soreness (DOMS) and muscle function. 18 participants attended the laboratory on 4 consecutive days. On the first day, participants completed 6 sets of 10 repetitions of unilateral eccentric-concentric knee flexions at a test speed of 1.05 rad.s(-1) using a Cybex Isokentic dynamometer to induce muscle damage of the hamstrings. Prior to the eccentric exercise bout and each subsequent morning, following an overnight fast, participants had a venous blood sample taken which was centrifuged immediately and plasma frozen at -80 degrees C until later analysis. Plasma IL-6 and sgp130 were unchanged at any time point during recovery but sIL-6R was significantly reduced at 48 h and 72 h post-exercise (p < 0.05). Plasma sIL-6R was correlated with DOMS at 48 h post EIMD (r = 0.45, p < 0.05) and peak muscle torque at 24 h and 48 h following EIMD (r = -.42; p < 0.05; r = -.57; p < 0.01 respectively). Our novel finding that sIL-6R concentrations are decreased 2-3 days following a single bout of EIMD may reflect a regulatory mechanism controlling the influx of different leukocyte subpopulations into damaged tissue, although this needs to be confirmed by future studies. Our data suggests an association between sIL-6R, perception of pain and reduced peak muscle performance post-EIMD but further investigation is warranted to explore this relationship and implications for exercise performance

Effect of high and low glycaemic index recovery diets on intramuscular lipid oxidation during aerobic exercise

Intramyocellular lipid (IMCL) and plasma NEFA are important skeletal muscle fuel sources. By raising blood insulin concentrations, carbohydrate ingestion inhibits lypolysis and reduces circulating NEFA. We hypothesised that differences in the postprandial glycaemic and insulin response to carbohydrates (i.e. glycaemic index; GI) could alter NEFA availability and IMCL use during subsequent exercise. Endurance-trained individuals (n 7) cycled for 90 min at 70 % V?O2peak and then consumed either high GI (HGI) or low GI (LGI) meals over the following 12 h. The following day after an overnight fast, the 90 min cycle was repeated. IMCL content of the vastus lateralis was quantified using magnetic resonance spectroscopy before and after exercise. Blood samples were collected at 15 min intervals throughout exercise and analysed for NEFA, glycerol, glucose, insulin, and lactate. Substrate oxidation was calculated from expired air samples. The 90 min cycle resulted in >2-fold greater reduction in IMCL in the HGI trial (3·5 (sem 1·0) mm/kg wet weight) than the LGI trial (1·6 (sem 0·3) mm/kg wet weight, P < 0·05). During exercise, NEFA availability was reduced in the HGI trial compared to the LGI trial (area under curve 2·36 (sem 0·14) mEq/l per h v. 3·14 (sem 0·28) mEq/l per h, P < 0·05 respectively). No other differences were significant. The findings suggest that HGI carbohydrates reduce NEFA availability during exercise and increase reliance on IMCL as a substrate source during moderate intensity exercise

Improved recovery from prolonged exercise following the consumption of low glycemic index carbohydrate meals

The present study examined the effects of the glycemic index (GI) of post-exercise carbohydrate (CHO) intake on endurance capacity and the metabolic responses during exercise the following day. Nine active males participated in two trials in a randomised crossover design. The experimental protocol was completed over two days. On day 1, subjects completed a 90 min treadmill run at 70% VO2 max (R1). Thereafter, they were supplied with a diet consisting of either high glycemic index (HGI) or low glycemic index (LGI) CHO and provided 8g CHOkg body mass (BM)-1.On day 2, after an overnight fast, subjects ran to exhaustion at 70% VO2 max (R2). Eight subjects completed both performance runs (R2). Run time to exhaustion during R2 was longer in the LGI trial (108.9 7.4 min) than in the HGI trial (96.9 4.8 min) (p<0.05). Average RER values were higher in the HGI trial compared to the LGI trial (p<0.05). Fat oxidation rates and free fatty acid concentrations were higher in the LGI trial than the HGI trial (p<0.05). The results of the study suggest that the increased endurance capacity during R2 was largely a consequence of the greater fat oxidation following the consumption of the LGI meals

Milk Consumption Following Exercise Reduces Subsequent Energy Intake in Female Recreational Exercisers

The aim of this study was to evaluate the effects of skimmed milk as a recovery drink following moderate–vigorous cycling exercise on subsequent appetite and energy intake in healthy, female recreational exercisers. Utilising a randomised cross-over design, nine female recreational exercisers (19.7 ± 1.3 years) completed a V̇O2peak test followed by two main exercise trials. The main trials were conducted following a standardised breakfast. Following 30 min of moderate-vigorous exercise (65% V̇O2peak), either 600 mL of skimmed milk or 600 mL of orange drink (475 mL orange juice from concentrate, 125 mL water), which were isoenergetic (0.88 MJ), were ingested, followed 60 min later with an ad libitum pasta meal. Absolute energy intake was reduced 25.2% ± 16.6% after consuming milk compared to the orange drink (2.39 ± 0.70 vs. 3.20 ± 0.84 MJ, respectively; p = 0.001). Relative energy intake (in relation to the energy content of the recovery drinks and energy expenditure) was significantly lower after milk consumption compared to the orange drink (1.49 ± 0.72 vs. 2.33 ± 0.90 MJ, respectively; p = 0.005). There were no differences in AUC (× 1 h) subjective appetite parameters (hunger, fullness and desire to eat) between trials. The consumption of skimmed milk following 30 min of moderate-vigorous cycling exercise reduces subsequent energy intake in female recreational exercisers

The incidence of urolithiasis in cats and dogs, and the influence of diet in formation and prevention of recurrence.

The two most common minerals found in uroliths from cats and dogs were calcium oxalate and magnesium ammonium phosphate, identified using accurate quantitative analytical techniques. Other mineral types included calcium phosphate and uric acid/ammonium urate. Cystine uroliths were found only in dogs. Trends towards age, breed and sex for each mineral type are discussed. The major urinary risk factors for calcium oxalate formation in dogs were found to be calcium and oxalate, although uric acid concentration was also increased in some dogs. Although individually these factors differentiated between calcium oxalate stone-forming dogs and clinically normal dogs, the relative supersaturation of urine with respect to calcium oxalate more clearly discriminated between the two groups. Differences between the urine composition of breeds susceptible to calcium oxalate formation (Miniature schnauzer, Cairn terrier and Cocker spaniel) were identified, when compared to a breed with a low risk of calcium oxalate formation (Labrador retriever). These included a lower urine volume (per kg bodyweight), higher urine specific gravity and increased calcium concentration. Increased dietary moisture and sodium were shown to reduce the severity of these differences, thereby reducing the risk of calcium oxalate crystallisation in susceptible breeds. This thesis also demonstrated that both dietary calcium and oxalate have to be controlled in order to minimise the risk of calcium oxalate formation in susceptible breeds. It was shown that in cats a moderately acidic urine pH within the range of 6-6.5 could minimise the risk of both calcium oxalate and MAP crystallisation compared to either a more acidic (5.8) or more alkaline urine pH (6.8). Finally, dietary potassium citrate supplementation, which is often recommended for the management of calcium oxalate formation in dogs had limited effects on urine analytes in the majority of dogs

The effect of the glycemic index of an evening meal on the metabolic responses to a standard high glycemic index breakfast and subsequent exercise in men

The study investigated the effect of the glycemic index of an evening meal on responses to a standard high glycemic index (HGI) breakfast the following morning. The metabolic responses to exercise 3 hours after breakfast were also investigated. 7 active males completed 2 trials. In each trial, participants were provided with an evening meal on day 1, either HGI or LGI (high or low glycemic index) carbohydrates. On day 2, participants were provided with a standard HGI breakfast, then performed a 60 minute run 3 hours later. Plasma glucose and serum insulin concentrates following breakfast were higher in the HGI trial compared to the LGI trial. During exercise there were no differences in substrate utilization. Results suggest that consuming a single LGI evening meal can improve glucose tolerance at breakfast but the metabolic responses to subsequent exercise were not affected

The effect of high carbohydrate meals with different glycemic indices on recovery of performance during prolonged intermittent high intensity shuttle running

This study examined the effect of high carbohydrate meals with different glycemic indices (GI) on recovery of performance during prolonged intermittent high-intensity shuttle running. Seven male semi-professional soccer players (age 23 ± 2 y, body mass [BM] 73.7 ± 9.0 kg and maximal oxygen uptake 58 ± 1.0 mL · kg-1 · min-1) participated in two trials in a randomized cross-over design. On day 1, the subjects performed 90 min of an intermittent high-intensity shuttle running protocol [Loughborough Intermittent Shuttle Test (LIST)]. They then consumed a mixed high carbohydrate recovery diet (8 g/kg BM) consisting of either high (HGI) (GI: 70) or low (LGI) (GI: 35) GI foods. Twenty-two hours later (day 2) the subjects completed 75 min of the LIST (part A) followed by alternate sprinting and jogging to fatigue (part B). No differences were found between trials in time to fatigue (HGI 25.3 ± 4.0 min vs. LGI 22.9 ± 5.6 min, P = 0.649). Similarly, no differences were found between trials for sprint performance and distance covered during part B of the LIST. In conclusion, the GI of the diet during the 22 h recovery did not affect sprint and endurance performance the following day