Objective This study aimed to investigate the physiological, hematological, and performance adaptations resulting from sequential blocks of endurance (EnT), speed (SpT), and strength (StT) training in elite Ethiopian middle- and long-distance male runners. Using a quasi-experimental repeated-measures design with a fixed order (EnT -> StT -> SpT), twenty male athletes (23.7 ± 3.2 years; 3000-10000 m events) completed three 6-week training blocks. Physiological (estimated VO2max, resting heart rate, running economy), hematological (hemoglobin, hematocrit, Red blood cell count (RBC), White blood cell count (WBC)), and performance measures (400 m speed, 5000 m time trial, 12-minute Cooper test) were assessed pre- and post-intervention using paired T-tests and repeated-measures ANOVA. Results The endurance training block produced significant improvements in aerobic and hematological parameters, including estimated VO2max (+ 6.20 ml·kg-¹·min-¹), resting heart rate (- 3.80 bpm), and hematocrit (+ 4.35%) (all p < 0.001). Subsequent strength and speed training blocks were associated with gains in running economy (StT: -4.2% oxygen cost, p < 0.01; SpT: -1.8%, p < 0.05) and 400 m speed (StT: -1.21 s, SpT: -1.00 s; both p < 0.001). All training modalities contributed to improved 5000 m times (EnT: -18 s, p < 0.01; SpT: -9 s, p < 0.01; StT: -6 s; p < 0.05). The sequential training approach resulted in complementary improvements across aerobic, anaerobic, and neuromuscular domains.
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