The physiological responses to a standard UK blood donation during sub-maximal and supra-maximal exercise across a five-day intervention period

Introduction: Previous studies investigating the effects of blood donation (BD) on exercise are limited primarily to V̇ O2max and adopt short intervention periods; thus, do not fully consider sub-maximal or supra-maximal exercise or fully appreciate the impact that BD can have on exercise in excess of 24 hours (h) post BD. Thus, results may be relevant to BD services, donors and (recreational) athletes. Methods: A systematic literature review and meta-analysis (1st experimental chapter) provided the grounding theory to aid in the formulation of further experimental chapters. Following ethical approval volunteers participated in four experimental studies. The first of which determined the effects of body composition and markers of cardiorespiratory fitness on haematological responses as a consequence of donating a unit (~470 ml) of blood. The next three experimental chapters determined the effects of BD over a period of up to 96 hours on O2 uptake kinetics (moderate and heavy domains), cardiac and ventilatory outputs, and power outputs during four repeated 15 s sprints. Results: The systematic review highlighted that sub-maximal and supra-maximal exercise data was limited. Experimentally, 3 h post BD Haemoglobin (Hb) decreased by 6.51 %, 24 h post BD a decrement of 7.09 % occurred. Further decreases of 2.68 and 2.55 % continued between 24-48 h and 48-72 h, with an increase of 1.98 % between 72-96 h (P < 0.0001). The V̇ O2 amplitude was unaffected by BD, tHb data via Near infrared spectroscopy (NIRS) had significant increases for moderate (P = 0.018) and heavy domains (P = 0.038). At 72 h, ventilatory and circulatory parameters were most affected (P < 0.05). Power outputs increased following BD; a main effect for time in Peak Power Output (PPO) occurred across 24-96 h BD period (P = 0.001, hp2= 0.35), at 24 h 222 (P = 0.001, hp = 0.39), 48 h (P = 0.013, hp = 0.35), 72 h (P = 0.006, hp = 0.31) and 96 h (P = 0.002, hp2 = 0.37). Conclusion: The UK BD guidelines advise caution with or avoiding strenuous exercise 12-24 h post BD. However, Hb continues to decrease in excess of 24 h highlighting implications for individuals wishing to undertake exercise for several days post BD. Ramifications of these findings are of benefit to BD athletes and non-athletes alike as well as blood transfusion services.