Presentation on theme: "Blood Doping. Maximal Aerobic Power Endurance sports which involve using large muscle groups, often during long periods of time. Other factors: – Aerobic."— Presentation transcript:
Maximal Aerobic Power Endurance sports which involve using large muscle groups, often during long periods of time. Other factors: – Aerobic exercise efficiency – Aerobic-anaerobic balance – Anaerobic capacity – Substrate availability – Muscle strength – Psychological factors
Maximal Oxygen Uptake (VO 2max ) Some elites have achieved >90 mL/kg/min! Due to large maximal cardiac output (Qmax, upwards of 40 L/min!), and Large arteriovenous oxygen difference (a-vO 2 diff). However, peak heart rate (HRmax) nothing special. Therefore, the huge Qmax is due to large stroke volume (>200 mL have been recorded for elite athletes) Performance has improved over last 50 years, the highest values of VO 2max have not.
What Limits VO 2max ? First addressed by Hill and Lupton (1923) Time VO 2max VO2VO2
What Limits VO 2max ? Pulmonary hemoglobin (Hb) saturation? Peripheral oxygen transport? – Capillary density? – Mitochondrial mass? – Enzyme concentrations? – Muscle size? Delivery of oxygen?
[Hb] Acute blood loss, carbon monoxide, and anemia: – Increase HR, blood lactate, rating of percieved exertion. No relationship in population between [Hb] & VO 2max – Total Hb Training does not increase [Hb] – Marked increase in total Hb – In fact, training is associated with dilutional pseudoanemia, a.k.a., “sports anemia”
Increasing [Hb]: Blood Doping 2-4 units (450-1800 mL) of whole blood drawn RBCs separated from plasma (centrifugation), frozen, and stored in glycerol. 2-3 months needed to restore [Hb] in hard training athletes. 3-5 days before competition, RBCs are washed with saline and infused Modern techniques preserve RBC function
Effects of Blood Doping First BD experiment: 1947 – Performance was enhanced Essentially no differences in performance with infusion of whole blood versus packed RBCs – O 2 -carrying capacity is what counts! Blood volume not changed, or only slightly increased within 12-14 d after infusion.
Effects of Blood Doping Hb and hematocrit (Hct) increase – Individual variation, of unknown origin After reinfusion of RBCs, submaximal VO 2 not increased. However: – Q reduced – HR lower – SV basically unchanged – Blood lactate concentration reduced Enhanced VO 2max and prolonged time to exhaustion. Increased oxygen availability – ↑[Hb] (average increase of 9 g/L) – ↑Qmax – ↑VO 2max (average increase of 0.31 L/min) – Qmax ∙ C a O 2 increased after infusion – Increased amount of O 2 “offered” to peripheral tissues during maximal exercise. Increase is linear up to [Hb] of at least 200 g/L – no difference in increase from anemia to normal; or normal to higher value. Bottom line: [Hb] important for performance!
Effects of Blood Volume (BV) Expansion Without blood doping, blood volume and total Hb are positively related to VO 2max. – In fact, expanded BV is one of the first adaptations to exercise training! What about plasma volume (PV) expansion? – Macrodex = PV expander – ↑SV (Diastolic filling, Frank-Starling mechanism) – Thus, ↑Qmax (HR unchanged) – However, the PV expansion results in dilution of Hb (↓[Hb]) in trained individuals – Acute PV expansion has only been shown to increase VO2 max untrained individual (↑PV may offset ↓[Hb]). – Bottom line: no change in VO 2max with PV expansion alone, unless you are untrained!
Risks & Side Effects Associated with Blood Doping? Blood pressure (BP)? – No effect of blood doping on systolic BP during submaximal exercise. – Presumably no effect on blood viscosity. – No increase in arterial BP at rest or exercise after reinfusion of RBCs Heterologous versus autologous infusion of packed RBCs or whole blood – Allergic reactions and infection possible with heterologous blood infusion.
Who’s [suspected of] been Blood Doping? US Olympic cycling team, 1984. Tyler Hamilton? Failed one test for heterologous RBCs – Lawyers argued he’s a chimera, then proposed a “vanishing twin” hypothesis. Operacion Puerto (2006) – hundreds of Spanish cyclists implicated. Russian hockey star Alexei Cherepanov (died, 2008) German speed skater & 5-time olympic gold medalist Claudia Pechstein banned for two years in 2009.
Detecting Blood Doping Heterologous blood infusion can be detected with advanced hematological and DNA techniques. Detecting ↑[Hb], ↑RBC fragility, ↑bilirubin, ↑iron, ↓erythropoietin – Need multiple blood samples from individual before and after infusion – logistically impractical After 2007 Tour de France doping scandals, cyclists required to carry “blood passport”. WADA promises that a reliable method for detection of autologous blood doping will be in place soon – Method and date of release are kept secret to avoid “tipping off athletes” – May assess the levels of 2,3-bisphosphglycerate in RBCs, which is degraded over time in stored RBCs. Bottom line: currently, no practical method is available for detection of autologous infusion of whole blood or packed RBCs.
All’s Fair in Love and War: Military Blood Doping US Special Forces – Fort Bragg, beginning 1993. – 24 before mission, small amount of packed RBCs infused into soldiers. Australian Defense Special Forces, 1998 – Senior nutritionist: “all’s fair in love and war…What we are trying to gain is an advantage over any potential adversary…What we will have is a head start.” Pugliese, David (2002). Canada's Secret Commandos. – Of the supplements/techniques tested for military performance enhancement, over 50 were rejected. – Just 6 were approved: caffeine, ephedrine, some energy drinks (mostly caffeine), modafinil, creatine and blood doping!
Conclusions Blood doping improves VO 2max and endurance performance – Due to increased [Hb], and thus oxygen transport Carries relatively little risk if conducted properly (in a clinical setting) with autologous blood. – Too many RBCs reinfused will thicken blood, increasing risk of stoke, heart attack and pulmonary embolism. Currently, no practical method for detecting the savvy blood doper (see: hematocrit regulations in in next chapter). The future? – Hb solutions – Artificial oxygen-carriers