The increase in core body temperature in response to exertional-heat stress can predict exercise-induced gastrointestinal syndrome.

Utilizing metadata from existing exertional and exertional-heat stress studies, the study aimed to determine if the exercise-associated increase in core body temperature can predict the change in exercise-induced gastrointestinal syndrome (EIGS) biomarkers and exercise-associated gastrointestinal symptoms (Ex-GIS). Endurance-trained individuals completed 2 h of running exercise in temperate (21.2-30.0°C) to hot (35.0-37.2°C) ambient conditions (n = 132 trials). Blood samples were collected pre- and post-exercise to determine the change in gastrointestinal integrity biomarkers and systemic inflammatory cytokines. Physiological and thermoregulatory strain variables were assessed every 10-15 min during exercise. The strength of the linear relationship between maximal (M-Tre) and change (Δ Tre) in rectal temperature and EIGS variables was determined via Spearman's rank correlation coefficients. While the strength of prediction was determined via simple and multiple linear regression analyses dependent on screened EIGS and Ex-GIS confounding factors. Significant positive correlations between Tre maximum (M-Tre) and change (Δ Tre) with I-FABP (rs = 0.434, p < 0.001; and rs = 0.305, p < 0.001; respectively), sCD14 (rs = 0.358, p < 0.001; and rs = 0.362, p < 0.001), systemic inflammatory response profile (SIR-Profile) (p < 0.001), and total Ex-GIS (p < 0.05) were observed. M-Tre and Δ Tre significantly predicted (adjusted R2) magnitude of change in I-FABP (R2(2,123)=0.164, p < 0.001; and R2(2,119)=0.058, p = 0.011; respectively), sCD14 (R2(2,81)=0.249, p < 0.001; and R2(2,77)=0.214, p < 0.001), SIR-Profile (p < 0.001), and total Ex-GIS (p < 0.05). Strong to weak correlations were observed between M-Tre and Δ Tre with plasma concentrations of I-FABP, sCD14, SIR-Profile, and Ex-GIS in response to exercise. M-Tre and Δ Tre can predict the magnitude of these EIGS variables and Ex-GIS in response to exercise.

Does intestinal epithelial integrity status in response to high-protein dairy milk beverage with or without progressive resistance training impact systemic inflammatory responses in an active aging population?

Increased resting systemic anti-inflammatory responses have previously been reported after a period of progressive resistance training (PRT) with daily consumption of a high-protein dairy beverage. The study aimed to investigate the independent and combined effects of consuming a high protein dairy milk beverage with or without a PRT on markers of intestinal epithelial integrity and selected systemic inflammatory responses in active older (≥50 yrs) adults. Thirty two (males n = 24, females n = 8) active older adults [mean (SD): Age 62 (7) years, weight 74.2 (14.0) kg, height 1.73 (10.0) cm, BMI 24.9 (4.0) kg/m2, and body fat mass: 25.8 (9.1)%)], that reported exercising ≥3/week (211 (91) min/week) were randomly allocated into one of four groups: dairy milk (DM), exercise and dairy milk (EX+DM), exercise alone (EX), and control (CON). Groups with EX underwent 12-weeks whole-body PRT program (x3 sessions/week), groups with DM consumed the beverage twice daily (30g protein/day), and CON was required to carry out their ad libitum dietary and exercise habits. Plasma concentrations of CRP, IL-1ß, IL-1ra, LBP, and sCD14 were determined by ELISA from samples collected at weeks 0, 6, and 12. Data were analyzed (SPSS v25.0) for group and time differences using a two-way repeated-measures ANOVA with post hoc analysis. No significant differences were observed for any of the measured plasma biomarkers. The previously observed increase in anti-inflammatory cytokine response is likely due to a muscular cellular response and not an indication of intestinal epithelial integrity disturbance and/or subsequent translocation of luminal originated pathogenic bacterial compounds.

Sarcopenic Characteristics of Active Older Adults: a Cross-Sectional Exploration.

BACKGROUND: Ageing is associated with a decline in skeletal muscle mass and function (strength and power), known as sarcopenia. Inadequate dietary protein and inactivity have been shown to accelerate sarcopenia outcomes, occurring at different rates in males and females. Regardless, active older adults who often exceed the exercise guidelines still show signs of sarcopenia. This study aimed to explore the link between age, physical activity, protein intake, and biological sex with skeletal muscle mass, strength, power, and physical capacity/performance in active older adults. Fifty-four active older adults were recruited from this trial and grouped according to age (middle aged: 50-59 years, and older age: ≥ 60 years), exercise volume (low: ≥ 90-149 min/week, moderate: ≥ 150-299 min/week, and high: ≥ 300 min/week), protein intake (low: < 0.8 g/kg body mass (BM), moderate: ≥ 0.8-1.19g /kg BM, and high: ≥ 1.2 g/kg BM), and biological sex (males and females). Skeletal muscle and fat mass (dual X-ray absorptiometry), strength (1-repetition maximum using leg press, chest press, lateral pull down, and hand grip), power (counter movement jump), and general fitness (cardiorespiratory capacity and gait speed) were assessed. Data were grouped based on variables, and a general linear model (ANCOVA) or an independent t test was used to determine between group differences. RESULTS: Fifty three of the total participants' data were analysed. The middle-aged group had 18%, 11%, and 10% higher leg press, chest press, and lateral pull down, respectively, compared to the older-aged group (p < .05). There were no significant differences between different levels of training volume and any of the outcomes. Higher protein intakes were associated with significantly less body fat mass (p = .005) and a trend towards a higher leg press (p = .053) and higher relative power (W/kg) (p = .056) compared with the moderate and low protein intake groups. Significant differences based on biological sex were observed for all outcomes except for gait speed (p = .611) and cardiorespiratory fitness (p = .147). CONCLUSIONS: Contributions of age, physical activity, daily protein intake, and biological sex can explain the individual variation in outcomes related to changes in body composition, strength, power, and/or cardiorespiratory fitness in a cohort of active older adults. The preprint version of this work is available on Research Square: https://www.researchsquare.com/article/rs-51873/v1 . TRIAL REGISTRATION: This trial is registered in the ANZCTR.org.au, no. ACTRN12618001088235 ( https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375286 ).

The Effects of a High-Protein Dairy Milk Beverage With or Without Progressive Resistance Training on Fat-Free Mass, Skeletal Muscle Strength and Power, and Functional Performance in Healthy Active Older Adults: A 12-Week Randomized Controlled Trial.

The study aimed to investigate the independent and combined effects of consuming a high-protein dairy milk beverage, twice daily, with or without a progressive resistance training (PRT) program on outcomes of age-related sarcopenia, in healthy active older (≥50 years) adults. In this 12-week, 2 × 2 factorial study, participants were randomly allocated into one of four groups: dairy milk beverage (DM), exercise and dairy milk beverage (EX+DM), exercise alone (EX), and control (CON). The EX group underwent a 12-week whole-body PRT schedule (three sessions/week) and a high-protein dairy milk beverage (DM) was consumed twice daily (30 g protein/day). At weeks 0, 6, and 12, body composition (iDXA), strength [one-repetition maximum (1RM): leg press, chest press, lateral (lat) pull-down, and handgrip], power (countermovement jump), cardiorespiratory fitness (VO2), and physical performance (gait speed) were measured. Before measurements, blood samples were collected to determine the immune (i.e., leukocyte trafficking and inflammatory cytokines) and hormonal (i.e., insulin, cortisol, IGF-1, testosterone, and estradiol) profiles. Participants (n = 37) completed the study within the controlled experimental conditions. Protein intake increased in the EX+DM [mean ± SD, 1.2 ± 0.2 to 1.8 ± 0.4 g/kg body mass (BM) per day-1] and DM (1.3 ± 0.5 to 1.8 ± 0.6 g kg-1 BM day-1) groups during the intervention. Absolute fat-free mass increased in the EX+DM [mean (95% confidence interval) = 0.65 (0.25-1.0) kg] and EX [0.49 (-0.44 to 1.40) kg] groups (P < 0.001) compared to DM [-0.54 (-1.6 to 0.05) kg]. Relative fat mass decreased (group*time, P = 0.018) in DM [-1.8% (-3.3 to -0.35%)] and EX+DM [-1.3% (-2.3 to -0.31%)], which was a greater reduction than that in the CON [0.10% (-0.80 to 1.0%)] group (P < 0.01). Relative maximal strength increased in both the EX and EX+DM (≥35%, P < 0.05) groups, but not in the DM and CON groups. The change in 1RM strength outcomes was higher in EX+DM compared to all other groups (53-78%, P < 0.01). There was an increase in resting plasma IL-10 concentration in EX+DM (88%), compared to all the other groups (P = 0.016). No other differences in systemic inflammatory cytokines were observed. There were no significant changes in all hormone concentrations measured among all groups. In conclusion, a high-protein dairy milk beverage providing additional protein did not further enhance the effects of PRT on outcomes of fat-free mass, power, or physical performance. However, there was a significant augmentative effect for high-protein dairy milk consumption on changes to maximal strength outcomes during PRT in healthy active older adults.

Diurnal versus Nocturnal Exercise-Effect on the Gastrointestinal Tract.

PURPOSE: The study aimed to determine the effect of diurnal versus nocturnal exercise on gastrointestinal integrity and functional responses, plasma lipopolysaccharide binding protein (LBP) and soluble CD14 (sCD14) concentrations (as indirect indicators of endotoxin responses), systemic inflammatory cytokine profile, gastrointestinal symptoms, and feeding tolerance. METHODS: Endurance runners (n = 16) completed 3 h of 60% V˙O2max (22.7°C, 45% relative humidity) running, on one occasion performed at 0900 h (400 lx; DAY) and on another occasion at 2100 h (2 lx; NIGHT). Blood samples were collected pre- and postexercise and during recovery to determine plasma concentrations of cortisol, catecholamines, claudin-3, I-FABP, LBP, and sCD14 and inflammatory cytokine profiles by ELISA. Orocecal transit time (OCTT) was determined by lactulose challenge test given at 150 min, with concomitant breath hydrogen (H2) and gastrointestinal symptom determination. RESULTS: Cortisol increased substantially pre- to postexercise on NIGHT (+182%) versus DAY (+4%) (trial-time, P = 0.046), with no epinephrine (+41%) and norepinephrine (+102%) trial differences. I-FABP, but not claudin-3, increased pre- to postexercise on both trials (mean = 2269 pg·mL-1, 95% confidence interval = 1351-3187, +143%) (main effect of time [MEOT], P < 0.001). sCD14 increased pre- to postexercise (trial-time, P = 0.045, +5.6%) and was greater on DAY, but LBP decreased (MEOT, P = 0.019, -11.2%) on both trials. No trial difference was observed for systemic cytokine profile (MEOT, P = 0.004). Breath H2 responses (P = 0.019) showed that OCTT was significantly delayed on NIGHT (>84 min, with n = 3 showing no breath H2 turning point by 180 min postexercise) compared with DAY (mean = 54 min, 95% confidence interval = 29-79). NIGHT resulted in greater total gastrointestinal symptoms (P = 0.009) compared with DAY. No difference in feeding tolerance markers was observed between trials. CONCLUSION: Nocturnal exercise instigates greater gastrointestinal functional perturbations and symptoms compared with diurnal exercise. However, there are no circadian differences to gastrointestinal integrity and systemic perturbations in response to the same exertional stress and controlled procedures.