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The aim of this study was to evaluate the effect of overload training on the function of peritoneal macrophages in rats, and to test the hypothesis that glutamine in vivo supplementation would partly reverse the eventual functional alterations induced by overload training in these cells. Forty male Wistar rats were randomly divided into 5 groups: control group (C), overload training group (E1), overload training and restore one week group (E2), glutamine-supplementation group (EG1), and glutamine-supplementation and restore 1-week group (EG2). All rats, except those placed on sedentary control were subjected to 11 weeks of overload training protocol. Blood hemoglobin, serum testosterone, and corticosterone of rats were measured. Moreover, the functions (chemotaxis, phagocytosis, cytokines synthesis, reactive oxygen species generation) of peritoneal macrophages were determined. Data showed that blood hemoglobin, serum testosterone, corticosterone and body weight in the overload training group decreased significantly as compared with the control group. Meanwhile, the chemotaxis capacity (decreased by 31%, p = .003), the phagocytosis capacity (decreased by 27%, p = .005), the reactive oxygen species (ROS) generation (decreased by 35%, p = .003) and the cytokines response capability of macrophages were inhibited by overload training. However, the hindering of phagocytosis and the cytokines response capability of macrophages induced by overload training could be ameliorated and reversed respectively, by dietary glutamine supplementation. These results suggest that overload training impairs the function of peritoneal macrophages, which is essential for the microbicidal actions of macrophages. This may represent a novel mechanism of immunodepression induced by overload training. Nonetheless, dietary glutamine supplementation could partly reverse the impaired macrophage function resulting from overload training.

Bioactive peptides either present in foods or released from food proteins during digestion have a wide range of physiological effects, including on gut function. Many of the bioactive peptides characterized to date that influence gut motility, secretion, and absorption are opioid agonists or antagonists. The authors review a body of experimental evidence that demonstrates an effect of peptides from food proteins on endogenous (nondietary) protein flow at the terminal ileum of simple-stomached mammals, including adult humans. At least some dietary peptides (1000-5000 Da) significantly enhance the loss of protein from the small intestine, causing an increased amount of protein to enter the colon. Food-derived peptides appear to either stimulate protein secretion into the gut lumen or inhibit amino acid reabsorption or influence both processes simultaneously. The effect of dietary peptides on small-intestine secretory-protein dynamics is discussed in the context of the major components of gut endogenous protein, sloughed cells, enzymatic secretions, mucin, and bacterial protein.

Caffeine (CAF) exerts a pressor effect both at rest and during exercise, as blood pressure is higher than with placebo. The effect of acute CAF ingestion combined with intense resistance training on cardiovascular function is unknown, however. The primary aim of the study was to examine changes in cardiovascular function after completion of fatiguing bench-press and leg-press exercise after CAF or placebo ingestion. Twenty-two resistance-trained men ingested CAF (6 mg/kg) or placebo 1 h pre exercise in a randomized, double-blind crossover design. They refrained from CAF intake and strenuous exercise 48 and 24 h pretrial, respectively. Heart rate and blood pressure were measured pre exercise. After a standardized warm-up, 1-repetition-maximum (1-RM) on the barbell bench press and leg press was tested. When it had been determined, a load equivalent to 60% of 1-RM was placed on the bar, and the subject completed repetitions to failure. Measurements of heart rate and blood pressure were immediately completed, and mean arterial pressure and rate-pressure product were calculated. Results showed significant (P < 0.05) increases in heart rate (+ 10 beats/min), systolic blood pressure (+ 8–10 mmHg), and rate-pressure product with acute CAF ingestion versus placebo. No change (P > 0.05) in diastolic blood pressure across time or treatment was shown. To prevent elevated blood pressure and potential enhanced risk of heart disease, CAF intake should be monitored in at-risk men who participate in resistance training.

Skeletal muscle mitochondrial capacity (mito), tissue blood flow (BF) capacity, and oxygen exchange capacity (e.g., DO₂) appear to be well matched. The different skeletal muscle fiber types and muscle remodeled, due to inactivity >(e.g., related to aging or disease) or exercise training, exhibit widely differing aerobics capacities (V̇O_2max). Yet, there are remarkably coordinated alterations in these 3 parameters in each of these conditions. With such a balance, there is likely shared control among these parameters in limiting (V̇O_2max) of muscle, although this is a matter of considerable debate. The reduction in aerobic capacity in elderly can be improved by submaximal aerobic exercise training; this is related to increases in muscle mitochondria concentration and capillarity, but probably not BF capacity, as this is limited by central cardiovascular function. Thus, exercise-induced biochemical adaptations and angiogenesis occur in the elderly. The increase in muscle capillarity likely contributes to the increased oxygen exchange capacity, typical of endurance type training. The increase in [mito] appears essential to realize the increased in muscle V̇O_2max with training and amplifies the rate-limiting influence of the muscle’s oxygen exchange capacity. Further, vascular remodeling induced by exercise in the elderly could be effective at improving flow capacity, if limited by peripheral obstruction. Thus, the limits to aerobic function specific to aged muscle appear most influenced by inactivity, whereas central cardiovascular changes impact whole body performance. Some may consider the aged myocyte as a small, inactive, normal myocyte in need of activity!

Iron deficiency may lead to anemia and may result in compromised endurance exercise performance. Iron deficiency has also been reported to adversely affect the immune system and has been associated with attenuation of natural killer cell (NK) activity. This study was conducted to examine the relationship between iron status and NK activity in highly conditioned female athletes. Ten collegiate female swimmers (SWM) and 9 inactive females (SED) participated in this investigation. Resting blood samples were obtained and analyzed for serum iron and ferritin. NK activity (% lysis) was determined using a whole blood method (⁵¹Cr release assay). No significant relationship was found between iron and NK activity (r = 0.55, p = .09), nor between serum ferritin and NK activity (r = 0.33. p = .35) for SWM. ANOVA revealed significantly greater NK activity for SWM (51.63 ± 15.79%) versus SED (30.34 ± 13.67%). Serum ferritin levels were not significantly different between SWM (20.38±8.62Ƞg · ml⁻¹) and SED (16.79±10.53Ƞg · ml⁻¹), nor were iron values different between groups (16.54 ± 2.17 μmol · L⁻¹ SWM; 11.92 ± 2.61 μmol · L⁻¹ SED). A significant relationship between iron status and resting immune function could not be established. Exercise training may affect NK activity; however, the influence of iron status on immune function requires further evaluation.

This study assessed the effects of resistive training (RT) with or without chromium picolinate (Cr-pic) supplementation on the 24-h urinary excretions of myo-inositol, D-chiro-inositol, and pinitol, as well as clinical indices of kidney and liver functions. Thirty-two nondiabetic subjects, age 62 ± 4 y, performed RT twice weekly for 12 wk and consumed either 924 μg Cr/d as Cr-pic (n = 17) or a placebo (n = 15). Whole-body strength increased in all subjects by 20% and urinary chromium excretion increased 47-fold in the Cr-pic group. Urinary myo-inositol, D-chiro-inositol, and pinitol were not changed with RT or influenced by Cr-pic. Serum indices of kidney and liver functions were within clinically normal ranges at baseline and the end of the study. These results suggest that RT did not influence the urinary excretions of inositols. High dose Cr-pic did not influence the urinary excretion of inositols and the selected indices of kidney and liver functions in conjunction with RT

The purpose of this study was to determine the effect of long-term Cr supplementation on blood parameters reflecting liver and kidney function. Twenty-three members of an NCAA Division II American football team (ages = 19–24 years) with at least 2 years of strength training experience were divided into a Cr monohydrate group (CrM, n = 10) in which they voluntarily and spontaneously ingested creatine, and a control group (n = 13) in which they took no supplements. Individuals in the CrM group averaged regular daily consumption of 5 to 20 g (mean ± SD = 13.9 ± 5.8 g) for 0.25 to 5.6 years (2.9 ± 1.8 years). Venous blood analysis for serum albumin, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, urea, and creatinine produced no significant differences between groups. Creatinine clearance was estimated from serum creatinine and was not significantly different between groups. Within the CrM group, correlations between all blood parameters and either daily dosage or duration of supplementation were nonsignificant. Therefore, it appears that oral supplementation with CrM has no long-term detrimental effects on kidney or liver functions in highly trained college athletes in the absence of other nutritional supplements.

Tonic vagal modulation of cardiac period (R-R interval) decreases with advancing age, but is greater in middle-aged and older adults who habitually perform aerobic exercise compared with their sedentary peers. Cardiovagal baroreflex sensitivity also declines markedly with age in sedentary adults but only 50% as much in regularly exercising adults. In previously sedentary middle-aged and older adults, a 3-month program of moderate aerobic exercise increases cardiovagal baroreflex sensitivity by 25%. Tonic (basal) sympathetic nervous system (SNS) activity increases with advancing age in both sedentary and habitually exercising adults. Despite this, SNS b-adrenergic support of energy metabolism (resting metabolic rate-RMR) declines with age in sedentary individuals. However, SNS b-adrenergic support of RMR is maintained with age inenduranceexercise-trainedadultsandthereforeismuchgreaterinmiddle-aged and older individuals who exercise regularly compared with their sedentary peers. Thus, regular aerobic (endurance) exercise modulates selective age associated impairments in autonomic nervous system-physiological function.