The effect of a standard whole blood donation on oxygen uptake and exercise capacity: a systematic review and meta-analysis

Impact of a single blood donation on hemoglobin mass, iron stores, and maximum oxygen uptake in pre-menopausal women-A pilot study

BACKGROUND

During whole blood donation (BD), 500 mL of blood is drawn. The time interval between two BDs is at least 8-12 weeks. This period might be insufficient for restoring hemoglobin mass (Hbmass) and iron especially in women, who generally have lower Hbmass and iron availability. Since both variables influence physical performance, this pilot study aimed to monitor Hbmass, iron status, and maximum oxygen uptake (V̇O2max) recovery in women after a single BD.

STUDY DESIGN AND METHODS

In 10 women (24.7 ± 1.7 years), Hbmass, hemoglobin concentration [Hb], iron status, and V̇O2max were assessed before and up to 12 weeks after a single BD.

RESULTS

BD reduced Hbmass from 562 ± 70 g to 499 ± 64 g (p < .001). Although after 8 weeks no significant mean difference was detected, 7 women had not returned to baseline after 12 weeks. [Hb] did not return to initial values (13.4 ± 0.7 g/dL) after 12 weeks (12.9 ± 0.7 g/dL, p < .01). Ferritin decreased from baseline until week 6 (40.9 ± 34.2 ng/mL vs. 12.1 ± 6.9 ng/mL, p < .05) and was not restored after 12 weeks (18.4 ± 12.7 ng/mL, p < .05), with 6 out of 10 women exhibiting iron deficiency (ferritin <15 ng/mL). V̇O2max was reduced by 213 ± 47 mL/min (7.2 ± 1.2%; p < .001) and remained below baseline after 12 weeks (3.2 ± 1.4%, p < .01).

DISCUSSION

For most pre-menopausal women, 12 weeks were not sufficient to recover from BD and achieve baseline Hbmass and iron stores resulting in prolonged reduction of aerobic capacity. A subsequent BD might lead to a severe anemia.

Blood, sweat, and fears: Athletes' perceptions of blood donation and engagement in physical activity

BACKGROUND

Athletes are a key group from which likely eligible donors could be sourced. While blood donation has been popularized as detrimental to athletic performance, little is known about how athletes perceive blood donation. The aim of this study was to investigate athletes' perceptions of the impacts of donating blood on their athletic performance and whether these influence their engagement with blood donation.

STUDY DESIGN AND METHODS

A total of 175 athletes (78 donors; 97 non-donors) prescreened as eligible to donate blood in Australia completed an online survey assessing the perceived impact of (i) donating blood on engagement and performance in physical activity (type of impact, direction, and duration) and (ii) engaging in physical activity on blood donation (magnitude of impact and modification of behavior).

RESULTS

We found that 37%-39% of our sample indicated that they had considered the impact of donating blood on their engagement or performance in physical activity, with the impact seen as negative but short term. Fatigue was the most commonly identified impact of donation on performance in physical activity. While the impact of donating did not account for athletes' non-donor status, many donors noted changing their engagement in physical activity pre- and post-donation to allow recovery, and aligning blood donation with their training schedule.

DISCUSSION

Athletes are a key community from which likely eligible donors could be sourced, however a significant proportion of athletes perceive that donating will negatively impact their athletic performance. Strategies to engage athletes with donation should acknowledge and facilitate athletes need to align their training with donating.

Hemoglobin modulation affects physiology and patient reported outcomes in anemic and non-anemic subjects: An umbrella review

Background: An abnormal hemoglobin concentration has a substantial effect on a person's quality of life and physiology. Lack of tools that effectively evaluate hemoglobin-related outcomes leads to uncertainty regarding optimal hemoglobin levels, transfusion thresholds and treatment targets. We therefore aim to summarize reviews that assess the effects of hemoglobin modulation on the human physiology at various baseline hemoglobin levels, and identify gaps in existing evidence. Methods: We conducted an umbrella review of systematic reviews. PubMed, MEDLINE (OVID), Embase, Web of Science, Cochrane Library and Emcare were searched from inception to the 15th of April 2022 for studies that reported on physiological and patient reported outcomes following a hemoglobin change. Results: Thirty-three reviews were included of which 7 were scored as of high quality and 24 of critically low quality using the AMSTAR-2 tool. The reported data generally show that an increase in hemoglobin leads to improvement of patient reported and physical outcomes in anaemic and non-anaemic subjects. At lower hemoglobin levels, the effect of a hemoglobin modulation on quality of life measures appears more pronounced. Conclusion: This overview has revealed many knowledge gaps due to a lack of high-quality evidence. For chronic kidney disease patients, a clinically relevant benefit of increasing the hemoglobin levels up until 12 g/dL was found. However, a personalized approach remains necessary due to the many patient-specific factors that affect outcomes. We strongly encourage future trials to incorporate physiological outcomes as objective parameters together with subjective, but still very important, patient reported outcome measures.

Impairment in maximal lactate steady state after carbon monoxide inhalation is related to training status

NEW FINDINGS

What is the central question of this study? What is the effect of an elevated COHb concentration following carbon monoxide inhalation on the maximal lactate steady state (MLSS) in humans and is this effect dependent on aerobic fitness? What is the main finding and its importance? An elevated COHb concentration intensified physiological responses to exercise at the MLSS- including heart rate, ventilation, and peripheral fatigue-in all participants and reduced the MLSS (i.e., destabilized the blood lactate concentration) in trained but not untrained males and females.

ABSTRACT

This study investigated whether a lower effective [Hb], induced by carbon monoxide (CO) inhalation, reduces the peak oxygen uptake (V̇O₂ peak) and the maximal lactate steady state (MLSS) and whether training status explains individual variation in these impairments. Healthy young participants completed two ramp incremental tests (n = 20 [10 female]) and two trials at MLSS (n = 16 [8 female]) following CO rebreathe tests and sham procedures (SHAM) in random orders. All fitness variables were normalized to fat-free mass (FFM) to account for sex-related differences in body composition, and males and females were matched for aerobic fitness. The V̇O₂ peak (mean [SD]: -4.2 [3.7]%), peak power output (-3.3 [2.2]%), and respiratory compensation point (-6.3 [4.5]%) were reduced in CO compared with SHAM (P < 0.001 for all), but the gas exchange threshold (-3.3 [7.1]%) was not (P = 0.077). Decreases in V̇O₂ peak (r = -0.45; P = 0.047) and peak power output (r = -0.49; P = 0.029) in CO were correlated with baseline aerobic fitness. Compared to SHAM, physiological and perceptual indicators of exercise-related stress were exacerbated by CO while cycling at MLSS. Notably, the mean blood lactate concentration ([La]) increased (i.e., Δ[La] > 1.0 mM) between 10 min (5.5 [1.4] mM) and 30 min (6.8 [1.3] mM; P = 0.026) in CO, with 9/16 participants classified as unstable. These unstable participants had a higher V̇O₂ peak (66.2 [8.5] vs. 56.4 [8.8] mL·kg FFM^-1 ·min^-1 , P = 0.042) and V̇O₂ at MLSS (55.8 vs. 44.3 mL·kg FFM^-1 ·min^-1 , P = 0.006) compared to the stable group. In conclusion, a reduced O₂ -carrying capacity decreased maximal and submaximal exercise performance, with higher aerobic fitness associated with greater impairments in both. This article is protected by copyright. All rights reserved.

Marked improvements in cardiac function in postmenopausal women exposed to blood withdrawal plus endurance training

The cardiac phenotype of a substantial fraction of the population, i.e., mature women, is mainly unresponsive to endurance training (ET), the most effective intervention to improve cardiorespiratory fitness. This study assessed whether a novel intervention comprising additional haemodynamic stimuli may overcome the generalized limitations to modify the cardiac phenotype of middle-aged and older women. Fifteen healthy postmenopausal women (52-75 yr) were recruited. Transthoracic echocardiography and central haemodynamics were assessed during incremental cycle ergometry (i) in baseline conditions, (ii) after standard (10%) blood withdrawal and (iii) subsequent 8-week ET. Main outcomes such as left ventricular (LV) function and structure and blood volume (BV) were determined. Phlebotomy induced a 0.5 ± 0.1 l reduction of BV, which was re-established after ET. Decrements in LV end-systolic volume (-27%) and increments in LV ejection fraction (+8%) during exercise as well as improved E/A ratio were detected after ET compared with baseline. In parallel, ET induced a 10% increment in LV mass without a concomitant increase in LV size. In conclusion, postmenopausal women exhibit large improvements in cardiac systolic and diastolic functions along with LV concentric remodelling in response to the sequenced combination of blood withdrawal and ET.

Differences in Cardiac Output and Aerobic Capacity Between Sexes Are Explained by Blood Volume and Oxygen Carrying Capacity

Whether average sex differences in cardiorespiratory fitness can be mainly explained by blood inequalities in the healthy circulatory system remains unresolved. This study evaluated the contribution of blood volume (BV) and oxygen (O₂) carrying capacity to the sex gap in cardiac and aerobic capacities in healthy young individuals. Healthy young women and men (n = 28, age range = 20–43 years) were matched by age and physical activity. Echocardiography, blood pressures, and O₂ uptake were measured during incremental exercise. Left ventricular end-diastolic volume (LVEDV), stroke volume (SV), cardiac output (Q), peak O₂ uptake (VO_2peak), and BV were assessed with precise methods. The test was repeated in men after blood withdrawal and reduction of O₂ carrying capacity, reaching women’s levels. Before blood normalization, exercise cardiac volumes and output (LVEDV, SV, Q) adjusted by body size and VO_2peak (42 ± 9 vs. 50 ± 11 ml⋅min^–1⋅kg^–1, P < 0.05) were lower in women relative to men. Blood normalization abolished sex differences in cardiac volumes and output during exercise (P ≥ 0.100). Likewise, VO_2peak was similar between women and men after blood normalization (42 ± 9 vs. 40 ± 8 ml⋅min^–1⋅kg^–1, P = 0.416). In conclusion, sex differences in cardiac output and aerobic capacity are not present in experimental conditions matching BV and O₂ carrying capacity between healthy young women and men.

Sex and age interaction in fundamental circulatory volumetric variables at peak working capacity

Background

Whether the fundamental hematological and cardiac variables determining cardiorespiratory fitness and their intrinsic relationships are modulated by major constitutional factors, such as sex and age remains unresolved.

Methods

Transthoracic echocardiography, central hemodynamics and pulmonary oxygen (O₂) uptake were assessed in controlled conditions during submaximal and peak exercise (cycle ergometry) in 85 healthy young (20–44 year) and older (50–77) women and men matched by age-status and moderate-to-vigorous physical activity (MVPA) levels. Main outcomes such as peak left ventricular end-diastolic volume (LVEDV_peak), stroke volume (SV_peak), cardiac output (Q_peak) and O₂ uptake (VO_2peak), as well as blood volume (BV), BV–LVEDV_peak and LVEDV_peak–SV_peak relationships were determined with established methods.

Results

All individuals were non-smokers and non-obese, and MVPA levels were similar between sex and age groups (P ≥ 0.140). BV per kg of body weight did not differ between sexes (P ≥ 0.118), but was reduced with older age in men (P = 0.018). Key cardiac parameters normalized by body size (LVEDV_peak, SV_peak, Q_peak) were decreased in women compared with men irrespective of age (P ≤ 0.046). Older age per se curtailed Q_peak (P ≤ 0.022) due to lower heart rate (P < 0.001). In parallel, VO_2peak was reduced with older age in both sexes (P < 0.001). The analysis of fundamental circulatory relationships revealed that older women require a higher BV for a given LVEDV_peak than older men (P = 0.024).

Conclusions

Sex and age interact on the crucial circulatory relationship between total circulating BV and peak cardiac filling, with older women necessitating more BV to fill the exercising heart than age- and physical activity-matched men.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-021-00409-9.

Minimal tactical impact and maximal donor safety after a buddy transfusion: A study on elite soldier performances in both laboratory and field environments

BACKGROUND

The major causes of death of combat casualties in austere environments are related to hemorrhage and occur early after injury. The implementation of a walking blood bank may overcome the logistical issues raised using blood component therapy. Nonetheless, it is important to ensure that this buddy transfusion is not going to compromise the mission success by altering the donor's performance. The results available so far cannot rule out this issue with certainty. Therefore, this study aimed at investigating the immediate effect of a 450-ml blood donation on the performances of elite soldiers in laboratory and field environments.

STUDY DESIGN AND METHODS

This double-blind, randomized controlled study included two experiments. For both experiments, subjects were randomly assigned either to a control group (n₁  = n₂  = 7) or to a 450-ml-blood-bag donation group (n₁  = 7 and n₂  = 8). All participants underwent before and after a potential blood donation a multifactorial assessment including adapted physical tasks, hematological variables, vigilance parameters, and subjective assessments.

RESULTS

No significant results were evidenced in this study. There was no impact of blood donation on the participants' performances in both the hospital and the combat-like environments.

CONCLUSION

From a donor's point of view, a 450-ml blood donation has no impact on the required abilities of our elite soldiers to fulfill a demanding tactical mission. Thus, the results of this study support the fact that buddy transfusions could be part of the operational clinical armamentarium in austere environments for elite soldiers when no blood components are available.

An Analysis of Exertional Safety After Blood Donation in Active Duty Military Personnel-A Feasibility Study

INTRODUCTION

Whole blood (WB) is the optimal resuscitation fluid in hemorrhagic shock. Military research focuses on mortality benefits of WB acquired through walking blood banks (WBBs). Few military-based studies on donation effects exist, almost exclusively performed on small special operation forces. No Department of Defense regulations for postdonation precautions in nonaviation crew members exist. Further study is warranted regarding safety and limitations in postdonation populations.

MATERIALS AND METHODS

A feasibility (n = 25) prospective interventional study examined the safety of exertion (defined as a 1.6-km treadmill run at volunteers' minimum passing pace for the Army Physical Fitness Test) following 1 unit of WB donation. Subjects served as their own controls, performing baseline testing 7 days before donation, with repeat testing 1 h following donation conducted by Armed Services Blood Program personnel. Adverse events, pre- and postexertion vital signs (VS) were evaluated.

RESULTS

There were no adverse events throughout testing. Only resting heart rate (68 vs. 73 beats · min-1, p < 0.01) and postexertion heart rate were significantly different among pre- and postdonation VS. Additional significant findings were time to attain postexertion normocardia (116 vs. 147 seconds, p < 0.01). A small but statistically significant change in Borg perceived exertional scores was noted (10.3 vs. 10.8, p < 0.05).

CONCLUSIONS

This feasibility study demonstrates the first safety test of regular military populations performing exertion immediately following the standardized WB donation. VS changes may translate into a small but significant increase in perceived postdonation exertion. Future studies should expand duration and intensity of exertion to match combat conditions.

Whole blood donors' post-donation symptoms diminish quickly but are discouraging: Results from 6-day symptom diaries

BACKGROUND

Whole blood donors may experience post-donation symptoms such as fatigue, dizziness, or headache after blood donation, which could influence donor retention. We aimed to examine post-donation symptoms during 1 week after whole blood donation, investigate donor characteristics associated with symptoms, and evaluate associations between symptoms and donor return.

METHODS

During 1 week, whole blood donors who donated successfully at one of the collection centers in The Netherlands were invited to participate. Three thousand seventy six donors filled in a diary, assessing post-donation symptoms during days 1 to 6 after donation. We used linear mixed models analyses to determine the change in post-donation symptoms after donation for male and female donors separately. Furthermore, we investigated associations between post-donation symptoms and donors' physical characteristics using multivariable regression and determined associations between symptoms and donor return.

RESULTS

Donors reported fatigue as the most common symptom, with approximately 3% of donors experiencing severe problems at the first day after donation. Multiple symptoms improved significantly up to day 3 after whole blood donation. Age, BMI, blood pressure (male donors), and blood volume (female donors) were significantly associated with post-donation symptoms. Donors with less fatigue after whole blood donation were more likely to return for their next donation within 31 days after receiving an invitation.

CONCLUSION

Post-symptoms improve up to 3 days after whole blood donation. Our results may help blood collection centers to identify donors more prone to post-donation symptoms and provide personalized information about the presence and course of post-donation symptoms, possibly increasing donor return rates.

Effect of an acute blood donation on oxygen uptake kinetics in moderate and heavy domains over a period of 96 hours

BACKGROUND

Studies determining the effects of blood donation (BD) on oxygen uptake kinetics are limited. This study aims to ascertain the effects of BD (~470 mL) over a period of 96 hours on oxygen uptake kinetics in moderate and heavy exercise domains.

STUDY DESIGN AND METHODS

Twelve participants (nine males and three females; 31.1 ± 11.7 years, mass 79.9 ± 12.8 kg, height 175.5 ± 7.5 cm) completed four consecutive days (24-96 hours) of moderate and heavy V˙O₂ on-kinetics trials pre BD and post BD. Visit one (0 hour), pre BD established hematological levels, V˙O_2max and Gas Exchange Threshold (GET). Subsequent visits comprised two 6-minute moderate (∆ 50% rest-GET) and 1 heavy (∆ 20% GET-V˙O_2max ) trial. Post BD 0 hour the participants donated blood post hematological testing only.

RESULTS

Despite non-significances for V˙O₂ amplitude, time constant-2 (tau₂ ) for V˙O₂ showed significant decreases at 24 and 48 hours, and tau₃ showed significant increases at 72 and 96 hours pre to post BD (P < .05). Hemoglobin (Hb) values reduced (P < .05) pre (14.48 ± 0.16 g·dL^-1 ) to post BD (13.47 ± 0.66 g·dL^- 1). Hb significantly decreased at 24, 48, 72, and 96 hours compared to 0 hour post BD (P < .05).

CONCLUSION

BD has no effect on V˙O₂ amplitude, but time-based components show sensitivity to reduced circulating O₂ ; with a decreased PO₂ a slower O₂ exchange across the blood myocyte barrier could result in altering O₂ kinetics.

Cognitive and physical performance are well preserved following standard blood donation: A noninferiority, randomized clinical trial

BACKGROUND

A walking blood bank (WBB) refers to the use of fellow combatants for battlefield blood donation. This requires pretesting combatants for infectious diseases and blood type. A fundamental prerequisite for this technique is that the donating soldier will suffer minimal physiological and mental impact. The purpose of the current study is to assess the effect of blood shedding on battlefield performance.

METHODS

This is a double-blind randomized control trial. Forty Israel Defense Forces combatants volunteered for the study. Participants underwent baseline evaluation, including repeated measurement of vital signs, cognitive evaluation, physical evaluation, and a strenuous shooting test. Three weeks after the baseline evaluation, subjects were randomized to either blood donation or the control group. For blinding purposes, all subjects underwent venous catheterization for the duration of a blood donation. Repeated vital signs and function evaluation were then performed.

RESULTS

Thirty-six patients were available for randomization. Baseline measurements were similar for both groups. Mean strenuous shooting score was 80.5 ± 9.5 for the control group and 82 ± 6.6 for the test group (p = 0.58). No clinically or statistically significant differences were found in tests designed to evaluate cognitive performance or physical functions. Vital signs taken multiple times were also similar between the test and control groups.

CONCLUSIONS

Executive, cognitive, and physical functions were well preserved after blood donation. This study supports the hypothesis that a WBB does not decrease donor combat performance. The categorical prohibition of physical exercise following blood donation might need to be reconsidered in both military and civilian populations.

The role of blood volume in cardiac dysfunction and reduced exercise tolerance in patients with diabetes

Blood volume is an integral component of the cardiovascular system, and fundamental to discerning the pathophysiology of multiple cardiovascular conditions leading to exercise intolerance. Based on a systematic search of controlled studies assessing blood volume, in this Personal View we describe how hypovolaemia is a prevalent characteristic of patients with diabetes, irrespective of sex, age, and physical activity levels. Multiple endocrine and haematological mechanisms contribute to hypovolaemia in diabetes. The regulation of intravascular volumes is altered by sustained hyperglycaemia and hypertension. Chronic activation of endocrine systems controlling fluid homeostasis, such as the renin-angiotensin-aldosterone system and vasopressin axis, has a role in progressive kidney desensitisation and diabetic nephropathy. Furthermore, albumin loss from the intravascular compartment reduces the osmotic potential of plasma to retain water. Hypovolaemia also affects the loading conditions and filling of the heart in diabetes. The elucidation of modifiable volumetric traits will plausibly have major health benefits in the diabetes population.

Association Between Hematological Parameters and Iron Metabolism Response After Marathon Race and ACTN3 Genotype

α-Actinin-3 (ACTN3 R577X, rs.1815739) polymorphism is a genetic variation that shows the most consistent influence on metabolic pathway and muscle phenotype. XX genotype is associated with higher metabolic efficiency of skeletal muscle; however, the role of ACTN3 polymorphism in oxygen transport and utilization system has not yet been investigated. Therefore, the aim of this study was to determine the influence of ACTN3 polymorphisms on hematological and iron metabolism response induced by marathon race. Eighty-one Brazilian amateur male endurance runners participated in the study. Blood samples and urine were collected before; immediately after; and 1, 3, and 15 days after the marathon race. Urine, hematological parameters, iron metabolism, and ACTN3 genotyping analyses were performed. The marathon race induced a decrease in erythrocytes, Hb, and Ht, and an increase in hematuria, creatinine, myoglobin, red cell distribution width, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, direct and indirect bilirubin and erythropoietin. Moreover, an elevation immediately or 1 day after the marathon race follows a reduction 3 or 15 days after the marathon race were observed on transferrin saturation and iron and transferrin levels. Hematological parameters and iron metabolism changes induced by marathon race were not observed in XX genotypes. Hematuria and decreased erythrocytes, Hb, Ht, and iron and transferrin levels were observed only in RR and/or RX genotypes but not in XX genotypes. The percentage of runners with hematuria, leukocyturia, iron deficiency, creatinine, myoglobin, and bilirubin imbalance was higher in RR compared to XX genotypes. ACTN3 polymorphism is associated with iron metabolism and hematological responses after endurance exercise. Despite these results being based on a small sample, they highlight a protective role of the XX genotype on hematological and renal changes induced by long-distance exercise. Therefore, these findings should be further replicated.

Association of blood donation with iron deficiency among adolescent and adult females in the United States: a nationally representative study

BACKGROUND

Blood donation results in a loss of iron stores, which is particularly concerning for young female blood donors. This study examines the association of blood donation and iron deficiency among adolescent and adult females in the United States.

STUDY DESIGN AND METHODS

A cross-sectional analysis was performed using data from the 1999-2010 National Health and Nutrition Examination Survey (NHANES). Females who reported their blood donation history in the preceding year and had serum ferritin (SF) measurements were included. Analyses were weighted and stratified by adolescents (16-19 years; n = 2419) and adults (20-49 years; n = 7228). Adjusted prevalence ratios (aPRs) were estimated by multivariable Poisson regression. Standard errors were estimated by Taylor series linearization.

RESULTS

Geometric mean SF levels (ng/mL) were lower in blood donors compared to nondonors among adolescents (21.2 vs. 31.4; p < 0.001) and among adults (26.2 vs. 43.7; p < 0.001). The prevalence of absent iron stores (SF < 12 ng/mL) was higher in blood donors compared to nondonors among adolescents (22.6% vs. 12.2%; aPR = 2.03 [95% confidence interval (CI) = 1.45-2.85]) and among adults (18.3% vs. 9.8%; aPR = 2.06 [95% CI = 1.48-2.88]). Additionally, the prevalence of iron deficiency anemia (SF < 26 ng/mL and hemoglobin < 12.0 g/dL) was also higher in blood donors compared to nondonors among adolescents (9.5% vs. 6.1%; aPR = 2.10 [95% CI = 1.13-3.90]) and among adults (7.9% vs. 6.1%; aPR = 1.74 [95% CI = 1.06-2.85]). Similar results were observed in a sensitivity analysis restricted to adolescents aged 16 to 18 years.

CONCLUSIONS

Blood donation is associated with iron deficiency among adolescent and adult females in the United States. These national data call for further development and implementation of blood donation practices aimed toward mitigating iron deficiency.

The acute effects of whole blood donation on cardiorespiratory and haematological factors in exercise: A systematic review

BACKGROUND

This systematic review aimed to collect the relevant historical and current literature to produce an informed analysis of the acute effects on cardiorespiratory and haematological factors following whole blood donation (~ 470 ml) during exercise. Testing the hypothesises that blood donation produces either no changes (Null) or produces significant changes (alternate) in haematology, [Formula: see text], heart rate, exercising power and time.

METHODS

Four databases of medical and science orientations were searched with terms sensitive to connections regarding exercise, blood donation (400-500 ml)/haematology, [Formula: see text], heart rate, exercising power and time. The study retrieval process utilised the PRISMA approach and selection was via an adapted scoring method according to the Consensus based Standards for the selection of health Measurements Instruments (COSMIN). Systematic review focused on 24-48 hrs post donation. Details of the PRSIMA checklist can be found in the accompanying online document.

RESULTS

Following scrutiny of 48 research papers by two independent assessors 8 experimental studies were included. Four studies showed a mean reduction for difference in [Formula: see text] (- 2.4 ± 1.4 ml∙kg-1∙min-1) and a medium effect size (-0.26). No statistical significance was present at the mean meta-analysis level, also the case for heart rate, time to exhaustion and power. A mean reduction was seen in haemoglobin (- 1.05 g.dL-1), haematocrit (- 3.71%) and red blood cells (- 0.44 Mio μL-1), very large effect size was observed (Cohen's d, -0.75, -1.16 and -4.23 respectively) and statistical significance (95% CI, -2.04, -0.54; -4.59, 2.28 and -4.37, -4.10 respectively).

CONCLUSION

Although individual studies show that [Formula: see text] Is reduced from blood donation pooled results show that [Formula: see text] is indeed not significantly reduced from blood donation 24-48 hrs post donation. Additionally sub-maximally there isn't enough data to produce substantial comparatives. Furthermore, this systematic review demonstrates that there are not enough high-quality studies regarding cardiorespiratory outcomes following blood donation.

Exercise Combined with Rhodiola sacra Supplementation Improves Exercise Capacity and Ameliorates Exhaustive Exercise-Induced Muscle Damage through Enhancement of Mitochondrial Quality Control

Mounting evidence has firmly established that increased exercise capacity (EC) is associated with considerable improvements in the survival of patients with cardiovascular disease (CVD) and that antistress capacity is a prognostic predictor of adverse cardiovascular events in patients with CVD. Previous studies have indicated that aerobic exercise (AE) and supplementation with Rhodiola sacra (RS), a natural plant pharmaceutical, improve EC and enable resistance to stress; however, the underlying mechanism remains unclear. This study explored the ability of AE and RS, alone or combined, to improve EC and ameliorate exhaustive exercise- (EE-) induced stress and elucidate the mechanism involved. We found that AE and RS significantly increased EC in mice and ameliorated EE-induced stress damage in skeletal and cardiac muscles (SCM); furthermore, a synergistic effect was detected for the first time. To our knowledge, the present work is the first to report that AE and RS activate mitophagy, mitochondrial dynamics, and biogenesis in SCM, both in the resting state and after EE. These data indicate that AE and RS synergistically improve EC in mice and protect SCM from EE-induced stress by enhancing mitochondrial quality control, including the activation of mitophagy, mitochondrial dynamics, and biogenesis, both at rest and after EE.

A combination of routine blood analytes predicts fitness decrement in elderly endurance athletes

Endurance sports are enjoying greater popularity, particularly among new target groups such as the elderly. Predictors of future physical capacities providing a basis for training adaptations are in high demand. We therefore aimed to estimate the future physical performance of elderly marathoners (runners/bicyclists) using a set of easily accessible standard laboratory parameters. To this end, 47 elderly marathon athletes underwent physical examinations including bicycle ergometry and a blood draw at baseline and after a three-year follow-up period. In order to compile a statistical model containing baseline laboratory results allowing prediction of follow-up ergometry performance, the cohort was subgrouped into a model training (n = 25) and a test sample (n = 22). The model containing significant predictors in univariate analysis (alanine aminotransferase, urea, folic acid, myeloperoxidase and total cholesterol) presented with high statistical significance and excellent goodness of fit (R2 = 0.789, ROC-AUC = 0.951±0.050) in the model training sample and was validated in the test sample (ROC-AUC = 0.786±0.098). Our results suggest that standard laboratory parameters could be particularly useful for predicting future physical capacity in elderly marathoners. It hence merits further research whether these conclusions can be translated to other disciplines or age groups.