Whey protein isolate reduces cortisol awakening response post-exercise

INTRODUCTION: Decreases in heart rate variability (HRV), disruptions in cortisol awakening response (CAR), and changes in Profile of Mood States (POMS), have been associated with fatigue and strenuous physical exercise. Whey protein isolate can affect stress responses. PURPOSE: To determine the effects of whey protein isolate supplementation on CAR, POMS, and HRV after strenuous exercise. Methods: Eleven recreationally active women (19 ± 2 yrs) completed a double blinded, crossover trial. Placebo was maltodextrin (PL), intervention was 25 g of maltodextrin and 25 g of whey protein isolate (WH). Exercise was 30 min at 70-75% VO2peak (21.7 ± 0.1 ml/kg/min), 5 min rest, and 30 s Wingate anaerobic test (WAnT). HRV and POMS were recorded. Repeated measures ANOVA were used to determine differences (p < 0.05) in salivary cortisol AUCg, POMS, HRV, and WAnT fatigue index (FI). Pearson correlation and multiple regression determined associations between CAR, POMS, and HRV to FI. Results: Cortisol AUC were significantly different (p = 0.033) between PL (33.4 ± 2.0 μg*hr/dL) and WH (30.9 ± 0.8 μg*hr/dL), with no significant differences in POMS, HRV, or FI (p > 0.05). Significant Pearson correlation on Day 3 during the PL, between POMS and FI (r = -.582, p = 0.030). Neither CAR, POMS, nor HRV was able to predict FI (all p > 0.05). CONCLUSIONS: Whey protein isolate may decrease CAR, but may have no effect on POMS, HRV, or FI, and no effect on short-duration sprint cycling performance, and or reduction in central fatigue may be minimal. No supporting funding. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

INTRODUCTION: The hypothalamus-pituitary-adrenal (HPA) axis plays a major role during stress responses and is associated with the secretion of cortisol. Serum cortisol concentration peaks between 30 and 45min after awakening, and is known as the cortisol awakening response (CAR). Disruptions in CAR have been associated with repetitive strenuous physical exercise. Whey protein branched chain amino acids (BCAA) compete for tryptophan transporters in the brain, subsequently reducing fatigue associated with exercise. PURPOSE: To determine the effects of whey protein on CAR after strenuous exercise, in recreationally active women, on post-exercise days. METHODS: Eleven recreationally active women (19 ± 2 yrs; VO2max = 31.6 ± 4.5 ml/kg/min) completed a double blinded, randomized, cross-over placebo trial, with a 7 day washout between trials. The supplement regimen (25g of maltodextrin (PL) or 25g of maltodextrin plus 25g of whey protein isolate (WH)) was given between 8am - 9am and 30min prior to exercise on 3 consecutive days of each trial. On Day 2 and 3 of each trial participants walked 30 min on a treadmill at 70-75% VO2max (21.7 ± 0.1 ml/kg/min), rested 5 min, and completed a 30s Wingate anaerobic threshold test (WAnT). Saliva (2ml) was collected on days 1-4 of PL and WH, between 6am and 8am, immediately upon waking and every 15 min for the next hour. Saliva samples were analyzed for cortisol concentration using an enzyme linked immunosorbent assay (ELISA) and the area under the curve (total AUC) was calculated for cortisol. A repeated measures ANOVA (2 trial x 4 days) was used to determine significant differences (p<.05) in cortisol AUC. A repeated measures ANOVA (2 trial x 2 day) was used to determine significant differences (p<.05) in WAnT fatigue index. RESULTS: Main effect means for AUC were significantly different (p = 0.033) between PL (33.36 ± 2.0 μg*hr/dL) and WH (30.88 ± 0.8 μg*hr/dL). No significant difference (p=0.149) in WAnT fatigue index means occurred between PL (20.79 ± 6.1% Day 2 & 21.97 ± 6.4% Day 3) and WH trials (22.52 ± 6.2% Day 2 & 22.78 ± 6.4% Day 3). CONCLUSIONS: Whey protein isolate may decrease CAR on post-exercise days, in recreationally active women, indicating a possible reduction in central fatigue associated with strenuous exercise, but may not alter the ability to perform short-duration sprint cycling.

BackgroundCortisol awakening response (CAR) as an indicator of psychological stress and related physical and psychiatric diseases has attracted growing attention from researchers. Although CAR changes have been investigated extensively in children with behavioral and psychiatric disorders, the association between CAR and conventional psychometric scales for healthy children has not been reported. The aim of this study was to investigate the association between salivary CAR and subscales of Profiles of Mood States (POMS), a self-assessment questionnaire widely used to evaluate the temporal emotional states of healthy children.FindingsThis study included 18 healthy girls aged 13–16 years. Saliva was collected immediately on awakening, 30 min and 60 min after waking, and then at 2-hour intervals from 9 am to 5 pm. The current mood state, including depression, anxiety, fatigue, and other psychometric profiles were assessed using POMS. The magnitude of salivary CAR and the area under the concentration-time curve (AUC) for diurnal salivary cortisol were compared with the profiles. There were significant positive correlations between the magnitude of CAR and the POMS subscales for "Depression-Dejection", "Tension-Anxiety", "Fatigue", and "Confusion". No correlation was found between the AUC salivary cortisol level and the psychometric profiles.ConclusionsSalivary CAR was associated with various mood states of healthy female children but diurnal salivary cortisol AUC was not. Salivary CAR may be a biomarker of the physical and mental condition of healthy female children.

Rationale/ statement of the problem: Stress is a complex phenomenon coordinated by several neural systems and has consequently been measured by several biomarkers. Salivary cortisol is the classical used stress biomarker representing the hypothalamic-pituitary-adrenal system. Heart rate variability (HRV), defined as the distance variability between consecutive R peaks, is increasingly used as marker of the autonomic nervous system and as a result also as a stress marker (defined as sympathetic over parasympathetic dominance). Associations between children’s salivary cortisol and HRV will be examined. Methods: In 190 children (5-10 year) of the Belgian ChiBS study salivary cortisol and HRV were sampled. Salivary cortisol samples were collected when waking up, 30 minutes and 60 minutes after wake-up and in the evening on two weekdays. HRV measurements in supine position were undertaken with Polar chest belts during 5 minutes. Apart from HRV time-domain analysis, also frequency-domain analysis was performed in the low-frequency (LF) and high-frequency (HF) bands. Multilevel growth curve modelling with adjustments for age, sex, physical activity and wake-up time was used to analyse the HRV associations with overall cortisol, cortisol awakening response (CAR) and cortisol diurnal decline. Results: Higher overall cortisol levels were negatively associated with mean RR, root mean square of successive differences (RMSSD), percentage of RR intervals differing more than 5 0ms (pNN50) and HF. A steeper diurnal decline was positively associated with normalised LF and the LF/HF ratio and negatively with HF. The CARwas positively associated with normalised LF and the LF/HF ratio and negatively with normalised HF. Conclusion: Higher salivary cortisol levels were associated with lower parasympathetic activity. A larger CAR and steeper diurnal decline were associated with a sympathetic over parasympathetic dominance. Consequently, the two main neural stress systems (represented by cortisol and HRV) show good agreement in reflecting children’s stress status, although not all parameters were significantly related. Measuring both pathways stays recommended as the pathways might be stimulated differently depending on the stressor.

Associations between the cortisol awakening response and heart rate variability

This study was designed to investigate physical education (PE) students the link between mood disturbances, caused by psychological or physical stressors associated with studying, and the autonomic nervous system modifications. PE students completed the profile of mood state (POMS) questionnaire at the end of the university year. Heart rate variability (HRV) was then measured during a head-up tilt test (HUT) in those with the highest and lowest total mood disturbance (TMD) scores on three successive POMS. Among the 218 students who completed the POMS (85 female and 137 male), 65 had high TMD scores, suggesting mood disturbances and fatigue. The final sample included 12 subjects in the potentially overtrained (POT) group and 16 subjects in the control (CTL) group. A greater decrease of two indices of the autonomic system (SD1 and RMSSD) was observed during the HUT in the POT than in the CTL group (P < 0.05). The depression (Dep) and vigor (Vig) subscales of POMS were correlated with several HRV indices. More specifically, in the POT group, the Vig score was correlated with autonomous activity in the supine position, and the Dep score with percentages of change of sympatho-vagal activity during the HUT. This suggests that (1) POT students could present a weaker autonomic response to HUT, (2) Dep and Vig subscales of the POMS questionnaire may indicate autonomic dysregulations.

BACKGROUND: Based on posturography parameters during sleep deprivation (SD), a mental fatigue index (MFI) was constructed for healthy male cadets.METHODS: There were 37 young male subjects who volunteered for two successive days of SD. Their posturography balance, profile of mood status (POMS), and heart rate variability (HRV) were measured at four different times (10:00 and 22:00 of day 1, 10:00 and 22:00 of day 2). According to the methods used in our previous research, similar MFIs based on posturography parameters were computed. Then, correlations of MFIs with POMS scores and HRV values were evaluated by linear and nonlinear methods including quadratic, S-curve, growth, and exponential analyses.RESULTS: MFI continued to increase during SD and MFI as the independent variable had quadratic relationships with fluster (R² 0.057), depression (R² 0.067), and anger (R² 0.05) scores of POMS. A linear correlation was found between MFI and the depression score (R² 0.045) and MFI correlated linearly (R² 0.029) and nonlinearly (R² 0.03) with heart rate. Similarly, MFI reflected changes in the time and frequency domain parameters of HRV, with linear (R²range: 0.0290.082) or nonlinear (R²range: 0.0300.082) relationships.DISCUSSION: The increase of MFI was linked with amplification of personal negative moods and an imbalance of autonomic nervous system activity. The findings suggest that MFI might be a potential indicator of mental fatigue and provide a method to prevent driving fatigue and human errors.Cheng S, Yang J, Su M, Sun J, Xiong K, Ma J, Hu W. Postural stability change under sleep deprivation and mental fatigue status. Aerosp Med Hum Perform. 2021; 92(8):627632.

Background: It has recently been noticed that the quantity of stress affects postural stability in young women. The study was conducted with the goal of investigating whether increased stress may damagingly effect posture control in 90 young men (71 right-handed and 19 left-handed) while maintaining an upright bipedal posture, while keeping their eyes open or closed. Perceived Stress Scale (PSS) was administered and changes in free cortisol levels were monitored (Cortisol Awakening Response, CAR) in order to evaluate the amount of stress present during awakening, while the Profile of Mood States (POMS) was used to estimate distress on the whole. Posture control was evaluated with the use of a force platform, which, while computing a confidence ellipse area of 95%, was engaged by the Center of Pressure through five stability stations and was sustained for a minimum of 52 s, with and without visual input. Another goal of the experiment was to find out whether or not cortisol increases in CAR were linked with rises of blood lactate levels. Results: CAR, PSS and POMS were found to be extensively related. Furthermore, it has been observed that increases in salivary cortisol in CAR are associated with small but significant increases in blood lactate levels. As expected, stress levels did affect postural stability. Conclusions: The results of the present study confirm that the level of stress can influence postural stability, and that this influence is principally obvious when visual information is not used in postural control.

Interest of analyses of heart rate variability in the prevention of fatigue states in senior runners

Salivary alpha-amylase and cortisol responsiveness following electrical stimulation stress in panic disorder patients

The cortisol awakening response (CAR) across the female menstrual cycle

Purpose: This study aimed to examine the activities of heart rate variability (HRV) and cortisol secretion as markers of the autonomous nervous system (ANS) and the hypothalamic-pituitary-adrenal axis (HPA) during the menstrual cycle in female athletes. Method: Saliva samples of the participants (n = 28) were collected successively at 0, 15, 30, and 60 min after awakening to assess cortisol awakening response (CAR) during each of four phases of the menstrual cycle (the menstruation, ovulation, luteal, and premenstrual phases). Diurnal saliva samples were collected at noon, in the evening (17:00) and 22:00 for cortisol analysis. HRV was measured in the menstrual and premenstrual phases at rest (12:00–14:00). Results: There was no difference between CAR parameters in the menstrual phases. CAR parameters and diurnal cortisol levels were significantly correlated with each other throughout the menstrual cycle. Mean cortisol was a strong predictor of the area under the curve (AUC: S = 0.042; R-Sq = 98.4%). Time-dependent parameters of HRV (standard deviation of the N–N interval [SDNN; P = .049] and the root mean square of the successive R–R differences [rMSSD; P = .038]) were significantly higher in the menstrual phase. There were no correlations between CAR and HRV parameters. Conclusions: We suggest that the hypothalamic-pituitary-adrenal axis activity and the autonomic nervous system work in a separate manner that is not affected by the menstrual phases in sportswomen. The present study contributed to a better understanding of the relationship between the dynamics of cortisol release and the autonomic nervous system in different phases of the menstrual cycle in female athletes.

This study was designed to assess the effects of Ramadan fasting on the profile of mood state and perceived exertion in young soccer players and aerobic and anaerobic performances during the Yo-Yo, repeated sprint ability (RSA) and the Wingate tests. Twenty junior male soccer players completed the Yo-Yo, the RSA, and the Wingate tests on three different occasions: one-week before Ramadan (BR), the second week (SWR) and the fourth week (ER) of Ramadan. The total distance (TD) covered and the estimated maximal aerobic velocity (MAV) during the Yo-Yo test were recorded. During the RSA test, peak power (PP) during each sprint, the percentage of decrement of PP (PD) and total work (Wtotal) were calculated. During the Wingate test, peak (P(peak)) and mean (P(mean)) powers and fatigue index (FI) were recorded. TD and MAV (P=0.01) during the Yo-Yo test and PP (P=0.01, P=0.004, P=0.001, P=0.01, P=0.03 for sprints 1, 2, 3, 4, and 5, respectively) and Wtotal (P=0.02) during the RSA test were significantly higher during BR than ER. Furthermore, muscle fatigue during the RSA test increased significantly from BR to ER (P=0.01). P(peak) and P(mean) during the Wingate test decreased significantly from BR to SWR and ER (P<0.0005). FI was higher during SWR (P=0.001) and ER (P<0.0005) than BR. In addition, rating of perceived exertion scores and fatigue estimated by the profile of mood state questionnaire were higher during Ramadan in comparison with BR. The present study suggests that both aerobic and anaerobic performances during the Yo-Yo, the RSA and the Wingate tests were affected by Ramadan fasting in young soccer players.

Adverse childhood experiences and diurnal cortisol pattern and heart rate variability in adults.

To the Editor: We have read the article by Barthel et al1 describing the first prospective trial to determine the predictive value of heart rate turbulence (HRT) in patients after acute myocardial infarction. In previous studies, the ability of HRT to predict risk was only determined retrospectively.2 We would like to critically discuss here the uniqueness of the emerging risk factor, HRT, in comparison with other parameters. Interestingly, Barthel et al1 found that HRT was the strongest ECG-based risk predictor. This conclusion is surprising for 2 reasons, as follows. First, in an editorial comment3 on the original article by Schmidt et al,2 it was noted that the positive predictive value of HRT is only moderately higher than other ECG risk parameters, and it was suggested that …