During exercise and physical activity, the body needs more oxygen than during usual daily activities. All the need for oxygen in the muscles is obtained from the bloodstream.
For the body to physiologically adjust according to the demands of increased activity, there is increased red cell production. More hemoglobin means more oxygen to give to the muscles which directly relates to the ability of the heart, lungs, and blood to do physical activity.
A higher concentration of hemoglobin equals higher athletic performance. This is the reason why athletes have erythrocytosis.
Abstract
Exercise training can increase total Hb and red cell mass, which enhances oxygen-carrying capacity. The possible underlying mechanisms are proposed to come mainly from bone marrow, including stimulated erythropoiesis with hyperplasia of the hematopoietic bone marrow, improvement of the hematopoietic microenvironment induced by exercise training, and hormone- and cytokine-accelerated erythropoiesis. Anemia is one of the most common medical conditions in chronic disease. The effects of exercise training on counteracting anemia have been explored and evaluated. The results of the research available to date are controversial, and it seems that significant methodological limitations exist. However, exercise training might be a promising, additional, safe and economical method to help improve anemia.
There is a need for further investigation into the effects of and guidelines for exercise interventions (especially strength training) in this population of patients, particularly among cancer patients who are undergoing or have undergone chemotherapy or radiation treatments. As the available data are limited, additional research to uncover the underlying mechanisms associated with the effects of exercise training on anemia is clearly warranted.
Exercise training can increase total Hb and red cell mass, which enhances oxygen-carrying capacity. The possible underlying mechanisms are proposed to come mainly from bone marrow, including stimulated erythropoiesis with hyperplasia of the hematopoietic bone marrow, improvement of the...
pubmed.ncbi.nlm.nih.gov
Is this only true with endurance exercise of is it true with resistance exercise, especially as intensity increases? Lets look at resistance training's effect on blood variables.
Abstract
The aim of this study was to examine short-term changes in blood rheological variables after a single bout of resistance exercise. Twenty-one healthy males completed three sets of 5 – 7 repetitions of six exercises at an intensity corresponding to 80% of one-repetition maximum (1-RM). The average duration of the exercise bout was 35 min. Venous blood samples were obtained before exercise, immediately after exercise and after 30 min of recovery and analysed for lactate, red blood cell count, haematocrit, haemoglobin, plasma viscosity, fibrinogen, total protein and albumin concentration.
Plasma volume decreased 10.1% following resistance exercise. This occurred in parallel with an increase of 5.6%, 5.4% and 6.2% in red blood cell count, haemoglobin and haematocrit; respectively. Plasma viscosity increased from 1.55 ± 0.01 to 1.64 ± 0.01 mPa · s immediately after resistance exercise before decreasing to 1.57 ± 0.01 mPa · s at the end of the recovery period. Similarly, fibrinogen, albumin and total protein increased significantly following resistance exercise. However, the rises in all these rheological parameters were transient and returned to pre-exercise values by the end of recovery. We conclude that a single session of heavy resistance exercise performed by normal healthy individuals alters blood rheological variables and that these changes are transient and could be attributed to exercise-induced haemoconcentration.
The authors write: To our knowledge, this is the first study to examine the effect of a 6-month resistance training program in older men and women. Our results demonstrate that intense resistance training seems to provide neither improvement nor detrimental effects on general hematological blood parameters in healthy older individuals. Nonetheless, further studies with a greater sample size are necessary to confirm these results.
These subjects were sedentary individuals, how does this change with highly trained individuals.
More.....
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Abstract
Formation of the blood clot is a slow but normal physiological process occurring as a result of the activation of blood coagulation pathways. Nature's guard against unwanted blood clots is the fibrinolytic enzyme system. In healthy people, there is a delicate dynamic balance between blood clot formation and blood clot dissolution. Available evidence suggests that exercise and physical training evoke multiple effects on blood hemostasis in normal healthy subjects and in patients. A single bout of exercise is usually associated with a transient increase in blood coagulation as evidenced by a shortening of activated partial thromboplastin time (APTT) and increased Factor VIII (FVIII). The rise in FVIII is intensity dependent and continues into recovery. The effects of acute exercise on plasma fibrinogen have yielded conflicting results. Thus, the issue of whether exercise-induced blood hypercoagulability in vitro mirrors an in vivo thrombin generation and fibrin formation remains disputable. Exercise-induced enhancement of fibrinolysis has been repeatedly demonstrated using a wide range of exercise protocols incorporating various exercise intensities and durations. Moderate exercise appears to enhance blood fibrinolytic activity without a concomitant activation of blood coagulation mechanisms, whereas, very heavy exercise induces simultaneous activation of blood fibrinolysis and coagulation. The increase in fibrinolysis is due to a rise in tissue-type plasminogen activator (tPA) and decrease in plasminogen activator inhibitor (PAI). The mechanism of exercise-induced hyperfibrinolysis is poorly understood, and the physiological utility of such activation remains unresolved. Strenuous exercise elicits a transient increase in platelet count, but there are conflicting results concerning the effect of exercise on platelet aggregation and activation. Few comprehensive studies exist concerning the influence of exercise training on blood hemostasis, making future investigation necessary to identify whether there are favorable effects of exercise training on blood coagulation, fibrinolysis, and platelet functions.
Another study done on inactive younger men 20-45
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Abstract
The purpose of this study was to investigate if strength training affects red blood cell variables in physically inactive men when taking into account seasonal variations. Seventy-four men aged 20 - 45 were randomly assigned to training (n = 52) and control (n = 22) groups. Training group underwent 20-week progressive strength training. Body composition and maximal voluntary contraction (MVC) during knee extension were measured before and after intervention. Fasting blood samples were analysed for haematocrit (Hct), count of red blood cells (RBC), haemoglobin (Hb), mean cell haemoglobin concentration (MCHC), and mean cell volume (MCV) at baseline, 10-week and 20-week follow-up. MVC and lean body mass increased in the training group. Hct, Hb and MCHC showed seasonal variation in the control group.
The training group increased their Hct from 44.7 ± 2.6 % to 45.4 ± 2.5 % (p = 0.026) while the control group decreased their Hct from 44.3 ± 2.2 % to 43.1 ± 2.6 % (p = 0.037) after 20-week intervention. By contrast to the control group, the training group increased their Hct (p = 0.001), RBC (p = 0.005) and decreased their MCHC (p < 0.001) from 10-week to 20-week follow-up.
We concluded that strength training could affect seasonal variation patterns of red cell variables. Unlike “sport anaemia” induced by endurance training, 20-week strength training elevated Hct.
I have lots of questions as to how the changes with highly trained individuals and timing of blood tests. Obviously exercise type and intensity cause changes in the red blood cells as an adaptation to exercise but there is very little research done in this area.
