Aggregation index (AI, %) and disaggregation threshold (γ at dISCmin, 1/sec) during weight reduction protocols.

<p>(A) During RWR, the aggregation index significantly increased Post 1 compared to Pre 1 and Pre 2 (<i>P</i><0.05, respectively) and decreased again Post 2 (<i>P</i><0.01). During GWR, AI decreased Post2 compared to Post 1 (<i>P</i><0.01). (B) Disaggregation threshold increased Post 1 RWR compared to Pre 1 and Pre 2 RWR (<i>P</i><0.05, respectively) and decreased Post 2 compared to Post 1 (<i>P</i><0.05). No change in disaggregation threshold was measured during GWR. Data in (A and B) are presented as mean ± S.E.M (n = 10).</p

Rapid Rather than Gradual Weight Reduction Impairs Hemorheological Parameters of Taekwondo Athletes through Reduction in RBC-NOS Activation

<div><p>Purpose</p><p>Rapid weight reduction is part of the pre-competition routine and has been shown to negatively affect psychological and physiological performance of Taekwondo (TKD) athletes. This is caused by a reduction of the body water and an electrolyte imbalance. So far, it is unknown whether weight reduction also affects hemorheological properties and hemorheology-influencing nitric oxide (NO) signaling, important for oxygen supply to the muscles and organs.</p><p>Methods</p><p>For this purpose, ten male TKD athletes reduced their body weight by 5% within four days (rapid weight reduction, RWR). After a recovery phase, athletes reduced body weight by 5% within four weeks (gradual weight reduction, GWR). Each intervention was preceded by two baseline measurements and followed by a simulated competition. Basal blood parameters (red blood cell (RBC) count, hemoglobin concentration, hematocrit, mean corpuscular volume, mean cellular hemoglobin and mean cellular hemoglobin concentration), RBC-NO synthase activation, RBC nitrite as marker for NO synthesis, RBC deformability and aggregation parameters were determined on a total of eight investigation days.</p><p>Results</p><p>Basal blood parameters were not affected by the two interventions. In contrast to GWR, RWR decreased activation of RBC-NO synthase, RBC nitrite, respective NO concentration and RBC deformability. Additionally, RWR increased RBC aggregation and disaggregation threshold.</p><p>Conclusion</p><p>The results point out that a rapid weight reduction negatively affects hemorheological parameters and NO signaling in RBC which might limit performance capacity. Thus, GWR should be preferred to achieve the desired weight prior to a competition to avoid these negative effects.</p></div

Hematological data of all subjects.

<p>Data are present as mean ± S.D. of n = 10.</p><p>RBC: red blood cell; Hb: hemoglobin; Hct: hematocrit; MCV: mean corpuscular volume; MCH: mean corpuscular hemoglobin; MCHC: mean corpuscular hemoglobin concentration; RWR: rapid weight reduction; GWR: gradual weight reduction.</p><p>Hematological data of all subjects.</p

Anthropometric data measured using bioimpedance analyzer BIA (body weight, body water and body fat).

<p>Data are present as mean ± S.D. of n = 10.</p><p>RWR: rapid weight reduction; GWR: gradual weight reduction; Procedure main effect: compared to</p><p>a: pre 1 RWR,</p><p>b: pre 2 RWR,</p><p>c: post 1 RWR,</p><p>d: post 2 RWR,</p><p>e: pre 1 GWR,</p><p>f: pre 2 GWR,</p><p>g: post 1 GWR;</p><p>*<i>P</i><0.05,</p><p>** <i>P</i><0.01.</p><p>Anthropometric data measured using bioimpedance analyzer BIA (body weight, body water and body fat).</p

Experimental study design.

<p>The study consisted of a three week baseline phase followed by a four day rapid weight reduction (RWR) with a simulated competition day. This was followed by a one week recovery time, a second three week lasting baseline phase, a four week gradual weight reduction (GWR) and a simulated competition day. At a total of eight investigation days (see arrows) anthropometry was measured and venous blood samples were taken.</p

RBC-NOSSer1177 levels during weight reduction protocols.

<p>(A) Bars showed statistically decreased RBC-NOS^Ser1177 phosphorylation Post 1 RWR compared to Pre 1 and 2 RWR (<i>P</i><0.05, respectively). Phosphorylation significantly increased Post 2 RWR compared to Post 1 (<i>P</i><0.05). (B) Pictures show representative RBC-NOS^Ser1177 photographs of Pre 1, Post 1 and Post 2 of RWR, respectively. Magnification for all images was 400-fold. Data in (A) are presented as mean ± S.E.M (n = 10).</p

Aggregation index (AI, %) and disaggregation threshold (γ at dISCmin, 1/sec) during weight reduction protocols.

<p>(A) During RWR, the aggregation index significantly increased Post 1 compared to Pre 1 and Pre 2 (<i>P</i><0.05, respectively) and decreased again Post 2 (<i>P</i><0.01). During GWR, AI decreased Post2 compared to Post 1 (<i>P</i><0.01). (B) Disaggregation threshold increased Post 1 RWR compared to Pre 1 and Pre 2 RWR (<i>P</i><0.05, respectively) and decreased Post 2 compared to Post 1 (<i>P</i><0.05). No change in disaggregation threshold was measured during GWR. Data in (A and B) are presented as mean ± S.E.M (n = 10).</p