The effects of carbohydrate supplementation during the second of two prolonged cycling bouts on immunoendocrine responses

Abstract

The purpose of this study was to examine the effect of carbohydrate (CHO) feeding during the second of two 90-min cycling bouts (EX1 started at 09:00 and EX2 started at 13:30) at 60% VO2max on leucocyte redistribution, neutrophil degranulation and oxidative burst and plasma IL-6 and stress hormone responses. This study consisted of two trials, which were completed in a counterbalanced order and separated by at least 4 days. Subjects (n=9) consumed a lemon flavoured 10% w/v CHO (glucose) or placebo (PLA) beverage during EX2: 500 ml just before exercise and 250 ml every 20 min during exercise. Venous blood samples were taken 5 min before exercise, immediately post-exercise, and 18-h post-EX2 for both trials. The main findings of this study were that ingestion of CHO compared with PLA during EX2 better maintained plasma glucose concentration, blunted the responses of plasma adrenaline, ACTH, cortisol, GH and IL-6, and attenuated the leukocytosis and monocytosis, but had no effect on neutrophil degranulation and oxidative burst activity. Furthermore, the immunoendocrine disturbances induced by two bouts of prolonged exercise returned to resting values within 18 h. These findings suggest that ingestion of CHO compared with PLA during the second of two bouts of 90-min cycling at 60% VO2max better maintains plasma glucose, blunts hypothalamic-pituitary-adrenal activation, and attenuates leucocyte trafficking, but does not affect neutrophil function. Furthermore, the disturbances of immunoendocrine responses induced by two bouts of prolonged exercise on the same day recover within 18 h.

Effects of Physical Exercise on Inflammatory Markers of Atherosclerosis

“…Consistent with this, IL-6 induces lipolysis in 3T3-LI adipocytes and increases fat oxidation in myotubes and in isolated rat soleus muscle [197]. In addition, it has been suggested that IL-6 influences glucose homeostasis during exercise [198][199][200]. In the latter study, young men performed a bicycle exercise at three separate occasions, at a relative high intensity or at a low intensity, with or without an infusion of recombinant (r)IL-6, which matched the circulating concentration of IL-6 in the high-intensity trial.…”

“…Nieman et al (203) found that muscle IL-15 mRNA levels were unchanged immediately after a 3-h run, and Ostrowski et al [216] found that plasma IL-15 (measured up to 6 h into recovery) did not change in response to 2.5 h of treadmill running. Skeletal muscle IL-15 mRNA levels, measured immediately after a 2-h weight training bout, did not differ from baseline [199], whereas plasma IL-15 protein was increased immediately after acute resistance exercise in one study [217].…”

“…This effect has been demonstrated for different types of training, for example running or cycling [199,200]. However, whereas supplementation with carbohydrates during exercise inhibits the exercise-induced increase of IL-6 in plasma, IL-6 mRNA expression within the contracting muscle is unaffected [201,202].…”

“…Adding to what we knew about this topic, recently a number of studies have clearly demonstrated that glucose ingestion during exercise attenuates the exercise-induced increase in plasma-IL-6 [195,[197][198][199][200]. This effect has been demonstrated for different types of training, for example running or cycling [199,200].…”

The Effect of a Carbohydrate and Protein Supplement on Resistance Exercise Performance,hormonal Response, and Muscle Damage

“…Nutritional supplementation can result in an anabolic hormonal response to both endurance and resistance exercise (5,17,18,21,23,33). Supplementing with carbohydrate and protein has been found to reduce the rise in cortisol and epinephrine (21,23,30), while elevating insulin during exercise (35) and insulin and growth hormone postexercise (5,33).…”