Background: Intermittent hypoxia training has been proposed as a potent facilitator of hematological adaptability, especially with respect to red blood cell proliferation and hemoglobin concentration. However, the comprehensive physiological implications of intermittent hypoxia training, as compared to normoxia training and intermittent hypoxia exposure, remain incompletely understood.

Methods: Ninety Sprague Dawley rats were randomly allocated into three experimental groups: intermittent hypoxia training, normoxia training, and intermittent hypoxia exposure, each consisting of 30 rats further stratified by gender. Hematological parameters, including hemoglobin level, red blood cell count, and hematocrit value, were evaluated at 24-hour intervals post the culmination of each training week for a span of 12 weeks. The study employed repeated measures analysis of variance to compare variations in these metrics across the experimental groups.

Results: Longitudinal assessment revealed a consistent uptrend in hemoglobin level, red blood cell count, and hematocrit value across all groups. However, the Sprague Dawley rats of intermittent hypoxia training group exhibited the most pronounced elevation in these parameters. A statistically significant elevation was observed in the intermittent hypoxia training group relative to both the intermittent hypoxia exposure and normoxia training groups starting from the seventh and eighth weeks, respectively.

Conclusion: Our findings confirmed the superior facilitative impact of intermittent hypoxia training on hematological parameters related to hemoglobin level, red blood cell count, and hematocrit value. These results contribute significantly to the extant body of knowledge concerning the intricate adaptive physiological mechanisms orchestrated under conditions of intermittent hypoxia and aerobic exercise. Furthermore, the data generated from this investigation serve as a robust foundational platform for future scholarly endeavors that aim to leverage these identified mechanisms for potential therapeutic applications.

Keywords: Intermittent hypoxia training; Sprague dawley rats; Hemoglobin; Red blood cell; Hematocrit.

Copy right Statement: Content published in the journal follows Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0). © Tian Z (2024).

Journal: The Journal of Clinical and Medical Images, Case Reports (JCMICR) is a fantastic resource for keeping up with the latest clinical advancements and for publishing case reports and clinical images related to a variety of medical illnesses.

Citation: Huang Z, Tian Z, Ran X, Jiang S, Jia W. The effect of intermittent hypoxia training on hematological parameters in sprague dawley rats: A randomized control trial. J Clin Med Images Case Rep. 2024; 4(5): 1741.

The concept of altitude or hypoxic training is a common practice for improving aerobic capacity and endurance performance [1]. Several strategies of altitude training, like “live high + train high”, “live high + train low” and “live low + train high” have been proposed [2-11]. They are based on adaptive changes of humans to chronic hypoxia [12]. Chronic exposure to altitude improves oxygen transport capacity by enhancing Erythropoietin (EPO) secretion [13], hemoglobin mass [14] and maximal oxygen uptake (VO₂ max) [11] thus promotes exercise performance [1]. However, not all athletes or teams have the resources to travel to high altitude environments on a regular basis. During the last years several strategies, such as the Intermittent Hypoxia Training (IHT), have been used to increase the athletes’ sea level performance [15-24]. IHT refers to the discontinuous use of normobaric or hypobaric hypoxia, in an attempt to reproduce some of these key features of altitude acclimatization, with the ultimate goal to improve sea-level athletic performance [25]. In this method, athletes live in normoxic conditions and train in hypoxic environment [15]. In the realm of altitude training, IHT emerges as a pivotal strategy, addressing the limitations inherent in traditional altitude training methods. Moreover, it stands as an instrumental technique to augment the athletic prowess of elite competitors. Within the intricate physiological tapestry of the human body, blood serves as a fundamental conduit, orchestrating the equilibrium and numeration of diverse cellular constituents within. The vitality and equilibrium of blood cells play an indispensable role in upholding the immune functionality [26], facilitating oxygen transference [27], and maintaining metabolic homeostasis [28]. Nevertheless, the existing body of research examining the ramifications of IHT on hematological parameters, especially in mammalian experimental studies, remains somewhat in its nascent stages. In light of this gap, the current investigation endeavors to delve into the repercussions of IHT on the hematological metrics of rodent subjects. By harnessing the rigor of randomized controlled trial and assessing hematological parameters encompassing Hemoglobin (HGB), Red Blood Cell (RBC), and Hematocrit (HCT) within Sprague Dawley (SD) rats, this study aims to elucidate the intricate biochemical and physiological mechanisms through which Intermittent Hypoxic Training (IHT) modulates hematological parameters, in comparison to Normoxia Training (NT) and Intermittent Hypoxia Exposure (IHE). The findings will hopefully illuminate the prospective utility of IHT, furnishing a robust academic foundation for ensuing dialogues centered on its potential to amplify athletic competence and other related domains.

Experimental subjects

For the purpose of this study, we recruited a cohort of 90 SD rats, each approximately two months of age. At the onset of the study, these specimens displayed an average body mass of 138.27±5.839 g. Throughout a preliminary two-week acclimatization phase, stringent controls were imposed upon the environmental parameters within the designated housing facility. Ambient temperatures were diligently regulated at 23±3 °C, while ensuring that the relative humidity hovered around 50±5% consistently. The photoperiod was meticulously set to mirror a 12-hour light/12-hour dark cycle. Prioritizing the holistic welfare of the SD rats, the housing chamber was equipped with efficient ventilation systems. To further cater to their cognitive needs and avert potential behavioral aberrations, an assortment of toys and stimuli was judiciously placed within their habitat. Nutritionally balanced feed and untainted water were dispensed at regular intervals. The maintenance regime included expedited removal of residual food and fecal matter, fortifying the hygiene and sanitation of the facility. To monitor their health trajectory, the SD rats underwent routine health evaluations, with the deployment of both prophylactic and therapeutic interventions when deemed essential. Subsequent to the acclimatization span, there was a notable augmentation in the SD rats’ body mass, registering at 187.74±9.69 g. Such meticulous preparatory and maintenance protocols underscore our commitment to upholding the credibility and methodological integrity of the study. All protocols of animal experiments complied with Animal Research: Reporting of In Vivo Experiments Guidelines [29]. This study was approved by the Ethics Committee of Shandong Institute of Petroleum and Chemical Technology (registered number: KY-2023-033).

Experimental groups design

Utilizing a randomized number table method, the 90 SD rats were arbitrarily divided into three distinct groups, each consisting of 30 individuals, further stratified by gender with 15 males and 15 females in each. We employed a hypoxia device to create an appropriate hypoxic environment and utilized an oxygen concentration meter for accurate oxygen content measurements.

IHT group

The preliminary week was dedicated to acclimatization, during which SD rats were introduced to a hypoxic milieu characterized by an oxygen volume fraction of 15%. Over subsequent weeks, a systematic decrement in this fraction was instituted, culminating in a reduction from the initial 15% to a final concentration of 10%. Training paradigms consisted of rigorous 15-minute aerobic sessions under hypoxic constraints, interspersed with five-minute recuperative intervals, aggregating to a daily total of 1.5 hours. This regimen was consistently maintained over a span of 12 weeks, demarcated by five active days followed by a rest phase of two days.

NT group

SD rats in this assembly were domiciled under normobaric parameters. Training paradigms consisted of rigorous 15-minute aerobic sessions, interspersed with five-minute recuperative intervals, aggregating to a daily total of 1.5 hours. This regimen was consistently maintained over a span of 12 weeks, demarcated by five active days followed by a rest phase of two days.

IHE group

The preliminary week was dedicated to acclimatization, during which SD rats were introduced to a hypoxic milieu characterized by an oxygen volume fraction of 15%. Over subsequent weeks, a systematic decrement in this fraction was instituted, culminating in a reduction from the initial 15% to a final concentration of 10%. The daily engagement involved 15 minutes of exposure to the hypoxic conditions, interspaced by five-minute intervals, cumulatively accounting for 1.5 hours. This regimen was consistently maintained over a span of 12 weeks, demarcated by five active days followed by a rest phase of two days.

Hematological evaluation

Prior to the initiation of the experiment and at 24-hour intervals post the culmination of each training week, blood specimens were meticulously extracted from the jugular vein. These samples were then subjected to detailed hematological assessments using a sophisticated animal blood analyzer. The metrics under evaluation included HGB level, RBC Count, and HCT value.

Statistical analysis

Data analysis was conducted using SPSS version 27.0. Quantitative data were presented as mean ± standard deviation. Repeated measures Analysis of Variance (ANOVA) was utilized to compare the variations in HGB level, RBC Count, and HTC value across different groups over the duration of the experiment. The level of significance was set at P=0.05.

Influence of different experiments on HGB level in SD rats

Prior to the commencement of the experimental procedures, one-way ANOVA confirmed that there were no statistically significant variations in the baseline HGB level across the three experimental SD rat groups (P>0.05). As the longitudinal study advanced, a discernible uptrend in HGB level was observed in all groups, culminating in a stabilization phase post the 10-week mark. Remarkably, the IHT group manifested the most pronounced elevation in HGB level. Beginning from the seventh week, a statistically significant elevation was recorded in the IHT group when compared to the IHE group. This difference became significant compared to the NT group as well, commencing from the eighth week (Tables 1-4, Figure 1)

Influence of different experiments on RBC count in SD rats

Prior to the commencement of the experimental procedures, one-way ANOVA confirmed that there were no statistically significant variations in the baseline RBC count across the three experimental SD rat groups (P>0.05). As the longitudinal study advanced, a discernible uptrend in RBC count was observed in all groups, culminating in a stabilization phase post the seven-week mark. Remarkably, the IHT group manifested the most pronounced elevation in RBC count. Beginning from the fourth week, a statistically significant elevation was recorded in the IHT group when compared to the IHE group. This difference became significant compared to the NT group as well, commencing from the fifth week (Tables 5-8, Figure 2)

Influence of different experiments on HCT value in SD rats

Prior to the commencement of the experimental procedures, one-way ANOVA confirmed that there were no statistically significant variations in the baseline HCT value across the three experimental SD rat groups (P>0.05). As the longitudinal study advanced, a discernible uptrend in HCT value was observed in all groups, culminating in a stabilization phase post the 10-week mark for IHT group, seven-week mark for NI group and IHE group. Remarkably, the IHT group manifested the most pronounced elevation in HCT value. Beginning from the eighth week, a statistically significant elevation was recorded in the IHT group when compared to the IHE group. This difference became significant compared to the NT group as well, for the eighth, ninth, 11^th, and 12^th week (Tables 9-12, Figure 3)

Table 1: Original data (HB)

Table 2: Descriptive statistics (HB)

Table 3: Paired comparison of time (HB)

Table 4: Paired comparison of groups (HB)

Table 5: Original data (RBC)

Table 6: Descriptive statistics (RBC)

Table 7: Paired comparison of time (RBC).

Table 8: Paired comparison of groups (RBC).

Table 9: Original data (HCT).

Table 10: Descriptive statistics (HCT)

Table 11: Paired comparison of time (HCT).

Table 12: Paired comparison of groups (HCT).