Is the feeling of heavy legs in overtrained athletes related to impaired hemorheology?

The feeling of having "heavy legs" (FHL) is commonly reported in the overtraining syndrome (OTS), i.e., the condition wherein an athlete is training excessively, yet performance deteriorates. Since FHL is also a sign of chronic venous insufficiency where it can be corrected by rheo-active drugs, and given the fact that OTS is also a hemorheologic disease associated with mild hemoconcentration, we investigated whether the FHL is associated with a hemorheologic profile. 37 athletes training 13.05+/-0.97 hr/week completed the French questionnaire of Overtraining (mean score: 11.66+/-1.96) and underwent a medical check-up including hemorheological measurements. 14 subjects quote the item: "I have the FHL". Although well matched with the 23 others for age and body composition, FHL subjects had higher plasma viscosity (1.44+/-0.05 vs 1.32+/-0.02 mPa.s; p<0.05) and a higher red cell aggregation as measured with laser backscattering (Affibio indices: final aggregation time "TF": 36.77+/-1.88 vs 44.26+/-2.37; p<0.05; aggregation index at 10 s "S10": 26.31+/-1.14 vs 21.92+/-1.19; p<0.05). The OTS score was correlated positively with plasma viscosity (r=0.549; p=0.008), whole blood viscosity (r=0.4458; p=0.03), and the following aggregability parameters: "S10" (r=0.4818; p=0.0232) and the aggregation index at 60 s "S60" (r=0.4601; p=0.0312). The OTS score was also correlated negatively with the aggregability parameters "TF" (r=-0.4432; p=0.0389) and the initial aggregation time "TA" (exponential relationship r=-0.458; p=0.03). These findings suggest that the feeling of heavy legs in overtrained athletes is related to OTS-related hemorheologic disturbances, namely mild plasma hyperviscosity and mild erythrocyte hyperaggregability.