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In three separate studies, we have observed that the rise in blood lactate during exercise is correlated to blood viscosity and red cell aggregation. Whether these results were related to an effect of blood rheology on lactate production by muscles or on lactate disappearance remains unknown. The modelling of post-exercise lactate kinetics allows a fair evaluation of lactate production by muscles (γ1) and lactate disappearance (γ2), the latter being easily measurable with simplified protocols. We thus investigated the relationships between pre- and postexercise blood rheology and γ2. Ten subjects (2 female and 8 males; age 16-45 yr, weight 62-106.5 kg) exhibiting a wide range of γ2 (from 2 to 7.7 × 10[sup -2] min[sup -1]) underwent a maximal exercise-test with post-exercise calculation of γ2 with the simplified formula γ2 = 0.0724+0.755(Lac8-Lac20)/(Lac8·Δt)-0.00684Lac20 where Lac8 and Lac20 are lactate concentrations 8 and 10 min after exercise stop at the level of V[sub O[sub 2 max]], as previously reported. During exercise whole blood viscosity η[sub b] increased (+15%, p < 0.01) due to a rise in hematocrit (p < 0.05) and plasma viscosity (+0.08 ± 0.03 mPa.s, p < 0.05), while red cell rigidity was unchanged. Red cell aggregation (Myrenne M1) increased by 11% (p < 0.05). Postexercise M1 (measured at V[sub O[sub 2 max]) was the only hemorheologic parameter correlated to γ2 (r = -0.697, p = 0.037). We find once again a statistical relationship between lactate at exercise and red cell aggregation. Microcirculatory adaptations influenced by red cell aggregation may influence lactate disposal (as reflected by γ2), adding its effect to that of the balance between carbohydrates and fat oxidation which is the major determinant of blood lactate concentrations at exercise in physiological conditions. [ABSTRACT FROM AUTHOR]

The GH-IGF axis has been recently suggested to modulate blood rheology in trained athletes, via GH effects on body water status and a possible action of IGF-I on erythrocyte deformability and aggregability. Another potential candidate for such a rheologic effect of the GH-IGF axis is insulin-like growth factor binding protein-1 (IGF-BP1) which is increased in trained people and correlated to fitness: IGF-BP1 is elevated in patients with polycythemia vera and stimulates erythroid burst formation in vitro. We investigated the statistical relationships between IGF-BP1 and blood rheology in athletes. 21 soccer players, age 24.5 ± 1.13 yr; body mass index 23.7 ± 0.38 kg/m²; VO[sub 2 max] 44.8 ± 7 ml.min[sup -1].kg[sup -1]). The major statistical determinant of IGFBP1 (measured at rest after overnight fast) was age (r = 0.752, p = 0.00013) which was not correlated with rheological parameters. IGF BP1 was negatively correlated with blood viscosity η(high shear rate r = -0.516, p = 0.024) and positively correlated with the percentage of extracellular water in total body water (ECW/TBW) (r = 0.488, p = 0.039). The previously reported correlations between IGF-I and both η (r = 0.637, p = 0.003) and red cell rigidity "Tk" (r = 0.696, p = 0.0137) were observed, but IGF-I and IGF-BP1 were not correlated to each other (r = -0.176 ns) and their correlations with η and Tk appeared to be independent when studied by multivariate analysis. Consistent with these correlations, subjects in the upper tertile of IGF-BP1 (>23.4 ng/ml) compared to those in the lower (<7.5 ng/ml) had a higher percentage of ECW/TBW (40.8 ± 0.4 vs 38 ± 0.8%, p = 0.033), a lower η (2.7 ± 0.05 vs 2.97 ± 0.06 mPa.s, p = 0.016), and a lower Tk (0.54 ± 0.05 vs 0.63 ± 0.01, p = 0.027). Thus, beside GH and IGF-I, IGF-BP1, which is reported to act on erythroid progenitors, exhibits statistical relationships with blood fluidity and... [ABSTRACT FROM AUTHOR]

Exercise training is known (1) to enhance the function of the GH-IGF-I system, which has profound effects on body fluid status; (2) to increase blood fluidity. Thus, we investigated during an exercise-test in 39 male elite sportsmen (age 23.7 ± 0.72 years; body mass index 23.7 ± 0.28 kg/m²) the possible relationships between GH and IGF-I status and the rheological properties of blood. Two correlations indicate a relationship between body hydration and fitness: isometric handgrip strength is correlated with the percentage of extracellular water in total body water (r = 0.432, p = 0.02) and the aerobic working capacity W[sub 170] is negatively correlated with hematocrit (r = -0.341, p = 0.039). Water loss during exercise appears to be inversely related to fitness as evaluated by W[sub 170] (r = -0.529, p = 0.05), and is positively correlated with the score of signs of overtraining (r = 0.725, p = 0.003) and with the red blood cell aggregation index (r = 0.584, p = 0.036). Finally, while the GH peak value is correlated with the extracellular water volume (r = 0.393, p = 0.02), IGF-I is correlated with blood viscosity (r = 0.546, p = 0.0003), suggesting that when IGF-I values are within the upper quintile (>340 ng/ml) IGF-I may unfavourably affect blood rheology. Among factors of blood viscosity, IGF-I exhibits a borderline correlation (p = 0.05) with "Tk" and the ratio IGF 1/IGFBP3 which reflects free circulating IGF-I is correlated with red cell aggregability measured with the Myrenne "M" (r = 0.485, p = 0.014) and S[sub 60] (r = 0.396, p = 0.494). These findings confirm the importance of hydration and dehydration as determinants of both blood rheology and exercise performance. Moreover, they suggest that values of IGF-I within the upper quintile are associated with an impairment of blood fluidity, possibly due to a direct effect of IGF-I on red cell deformability and aggregability. [ABSTRACT FROM AUTHOR]

The paradox of hematocrit in exercise physiology is that artificially increasing it by autotransfusion or erythropoietin doping improves Vo[sub 2 max] and performance, while in normal conditions there is a strong negative correlation between hematocrit and fitness, due to a training-induced "autohemodilution". We aimed at investigating: (a) which is the physiological range of hematocrit in highly trained professional footballers; (b) what are the characteristics of athletes with high vs low hematocrit? We determined in 77 healthy male footballers the physiological range (mean ± sd) of hematocrit: 42.3 ± 2.74, (range -2σ/+ 2σ = 36.8-47.8%) thus defining boundaries of quintiles of distribution for this parameter: 40, 41.6, 42.9, 44.6. In another sample of 42 male footballers we compared three groups: lowest quintile (n = 8), highest quintile (n = 5) and the three middle quintiles considered together (n = 29). Athletes in the lowest quintile compared to those in the four other quintiles had a lower value of blood viscosity (-8%, p < 0.01) but this difference disappeared after correction for hematocrit. These subjects with low hematocrit had also higher values of the following parameters: aerobic working capacity (p < 0.01); isometric adductor strength (p = 0.02); crossover point of carbohydrate oxidation (70% carbohydrates/30% lipids) (p < 0.05); insulin like growth factor binding protein 1 (p < 0.0001). Athletes in the highest quintile had higher red cell aggregability (Myrenne index "M1" 8.45 ± 0.38 vs 6.82 ± 0.62, p < 0.04) and a higher disaggregability threshold γ[sub D] (72.6 ± 22.63 vs 44.49 ± 1.37, p < 0.01 ) and a lower percentage of water in fat-free mass (p < 0.02). On the whole sample hematocrit was negatively correlated with aerobic working capacity (W[sub 170] r = -0.329, p: 0.007; W[sub max] (% of expected value) r = -0.552, p = 0.008; Vo[sub 2 max] (% of expected value) r = -0.543, p = 0... [ABSTRACT FROM AUTHOR]

Focuses on a study which highlighted three-dimensional kinematic and dynamic parameters in analyzing the snatch pull in weight lifting. Materials and methods; Results; Discussion and conclusion.

The goal of this anatomical study is to prove that reconstruction of the flexor retinaculum in carpal tunnel syndrome surgery is a reliable procedure and can improve the results of this procedure. In the first static study, we noted that when left to heal spontaneously, after 3 months the gap between the two edges of the cut retinaculum remained equal to or even larger than the gap created at the time of the surgery. A special Canaletto™® implant was created to achieve this reconstruction. It is technically possible to do this reconstruction by a 2 to 3 cm surgical approach in the palm. In another, dynamic study, we used a transducer to analyse the forces borne by the retinaculum during flexor tendon contraction. We compared these forces in a normal retinaculum, a reconstructed retinaculum with the Canaletto™® implant and a retinaculum opened endoscopically. This reconstruction conserves the anterior continuity of the retinaculum, allows excellent carpal tunnel decompression and immediately permits near-physiological forces. We discuss the advantages and the limits of this reconstruction. We think that this new surgical technique in the Carpal Tunnel Syndrome (CTS) will be able to improve the results, particularly in recurrences, in wrist malunion with CTS, in cases with severe electromyographic change with a sensory conduction speed of under 15 m.s–1 and in metabolic CTS. As always, his implant needs to be evaluated through a mid and long term clinical follow-up. By recovering better grip strength and reducing postoperative pain, this surgical technique can decrease the time needed to return to work and hence the economic costs of CTS surgery. [Copyright &y& Elsevier]

Introduction. – The rugby is a discipline requiring, in the same time, strength qualities and a high aerobic capacity for repeating intense exercises over 2 × 40 min.Synthesis of the facts. – Fourteen rugby players performed a maximal progressive test of journey (running) then two sequences of 40 min, respectively, to 60% and 80% of HRmax, interrupted with pushes on a yoke with constraint gauges. At 80% HRmax, the mean scrummaging force (1466 ± 244 N) was lower (P < 0.05) than at 60% HRmax (1523 ± 266 N).Conclusion. – The qualities of specific force are directly affected by the intensity of running. Therefore, there is a need to optimize the aerobic potential notably for the players of the first line directly concerned by the fight. [Copyright &y& Elsevier]