The Impact of Hypoxia on the Biochemical and Morphological Parameters of Blood in Rowers.

I stage. The Polish national rowing team athletes, 13 males, were randomly divided into two groups:

• The hypoxic group (H) included 8 rowers participating in sports training and the LHTL intervention, with progressive normobaric hypoxic exposure corresponding to simulated altitudes of 2000, 2500, and 3000 m.
• The control group (C) consisted of 5 rowers participating only in sports training and living in normoxic rooms at the same sports camp. Rowers were observed during the preparatory period. The hypoxic group lived and slept in hypoxic rooms for at least 8-14 hours per day. During the camp, all rowers followed the same training schedule and diet. All participants' saturation and heart rate were measured daily, morning and evening, throughout the camp period. Venous blood samples were taken four times, at the beginning of the camp (Baseline), after 6 days, after 12 days, and after 18 days of the camp. Body composition parameters such as body mass index, body fat, and free fat mass were estimated using the bioelectrical impedance method of a Tanita BC 418 analyzer (Japan). Data analysis was performed using Statistica. The response to hypoxia is very individual. Depending on many factors, such as training type, duration, intensity, or hypoxic stimulus, hypoxia affects athletes in various ways. The results of this study have shown that the blood parameters did not increase significantly in the hypoxic group compared to the control group. However, reticulocytes, immature red blood cells, have shown significant differences after 18-d LHTL between groups. Further research should be carried out to investigate an optimal hypoxic dose and time, which will raise EPO, VEGF, and morphology variables.

II stage. Fourteen elite male rowers from the Polish national rowing team participated in the second stage and were randomly allocated to the LHTL group (n = 8) or the normoxic control group (n = 6). Both groups followed the same standardized training program. The LHTL intervention lasted 14 consecutive days and involved progressive normobaric hypoxic exposure corresponding to 2000-3000 m for approximately 14-16 h/day, while all training sessions were performed under normoxic conditions. Blood samples were collected at baseline, after 7 and 14 days of the intervention, and 8, 14, and 42 days after completion. Hematological variables, EPO, VEGF, iron-related indices, CK activity, and lipid-profile variables were assessed, while SpO₂ and resting HR were monitored throughout the intervention.

Inclusion criteria

• Male national-team rowers aged ≥18 years.
• Regular participation in rowing training.
• Participation in the training camp.

Exclusion criteria

• Exposure to hypoxic conditions or altitude above 1500 m within 1 month before the study.
• Medical contraindications or adverse symptoms associated with hypoxic exposure.
• Injury or health condition preventing participation in the training program.