An intense physical exercise induces an inflammatory reaction as demonstrated by the delayed increase in blood of acute phase proteins and among them of C-reactive protein (CRP). There is also evidence for a diminished acute phase reaction due to regular exercise suggesting a suppression of the inflammatory response through training. With this background CRP was measured by a sensitive enzyme immunoassay under resting conditions before and after 9 months of training in 14 subjects preparing for a marathon with the aim of studying the effect of training on the base-line CRP concentration. The mean distance run per week increased significantly from 31 +/- 9 km at the beginning to 53 +/- 15 km after 8 months of training (p < 0.01). The aerobic capacity rose significantly after training as demonstrated by the increase of running velocity during a maximal treadmill test from 3.82 +/- 0.29 m/s pre-training to 4.17 +/- 0.17 m/s post-training at a blood lactate concentration of 4 mmol/L (p< 0.01). In 10 of 12 runners base-line CRP was diminished after training in spite of a continuous increase of training intensity. The CRP median fell from 1.19 mg/L before to 0.82 mg/L after training (p < 0.05). Since intense physical exercise is known to be associated with an inflammatory reaction of muscles and tendons, the CRP decrease was unexpected. In 2 subjects the CRP concentration rose markedly because of a borrelia infection and a knee injury, respectively. These values were caused by a pathological condition and were not considered for the statistical evaluation. In 10 non-training control subjects the CRP median did not change significantly during the same 9 months period. The decrease of the CRP base-line concentration after training suggests that intensive regular exercise has a systemic anti-inflammatory effect. This is of particular interest with regard to several recent reports confering on the concentration of CRP in plasma a predictive value for the risk of cardiac infarction, venous thrombosis or stroke.
During low-intensity exercise stages of the lactate threshold test, blood lactate concentrations gradually diminish due to the predominant utilization of total fat oxidation. However, it is unclear why blood glucose is also reduced in well-trained athletes who also exhibit decreased lactate concentrations. This review focuses on decreased glucose and lactate concentrations at low-exercise intensity performed in well-trained athletes. During low-intensity exercise, the accrued resting lactate may predominantly be transported via blood from the muscle cell to the liver/kidney. Accordingly, there is increased hepatic blood flow with relatively more hepatic glucose output than skeletal muscle glucose output. Hepatic lactate uptake and lactate output of skeletal muscle during recovery time remained similar which may support a predominant Cori cycle (re-synthesis). However, this pathway may be insufficient to produce the necessary glucose level because of the low concentration of lactate and the large energy source from fat. Furthermore, fatty acid oxidation activates key enzymes and hormonal responses of gluconeogenesis while glycolysis-related enzymes such as pyruvate dehydrogenase are allosterically inhibited. Decreased blood lactate and glucose in low-intensity exercise stages may be an indicator of recovery ability in well-trained athletes. Athletes of intermittent sports may need this recovery ability to successfully perform during competition.
In combat sports such as taekwondo (TKD), athletes rapidly reduce body weight to achieve a desired weight category. Competition takes place 16–24 h after weigh-in and thus, the recovery time is an important factor for competition performance. The purpose of this study was to investigate the impact of rapid weight reduction (RWR) on athletic performance and associated hemorheological properties considering relevant recovery time. Five male TKD athletes reduced body weight by 5% within 3½ days. A simulated competition day (SCD) was carried out after a 16 h recovery period. Parameters were measured before RWR, at weigh-in and before and after three TKD simulation matches (SMs) at SCD. Same set-up was conducted but without RWR as control. Basal blood parameters, red blood cells (RBC) deformability and aggregation, serum glucose and fibrinogen were determined. During SMs, heart rate (HRpeak, HRmean), oxygen uptake (VO2peak, VO2mean), peak lactate (Peak La-), difference of lactate (ΔLa) and energy systems (anaerobic-alactic, -lactic and aerobic) were analyzed. Basal blood parameters remained unaltered during the interventions. RBC deformability was reduced and aggregation was increased after RWR but values returned to baseline after recovery and were not affected by the SMs. Glucose level was not affected by the interventions. Kick frequency in SMs was higher after RWR which might be responsible for higher HRpeak, VO2peak, VO2mean, Peak La-, ΔLa- and aerobic demand. The 16 h recovery is sufficient to regenerate measured physiological and hemorheological parameters. TKD-specific performance was not negatively affected during SMs after RWR.
PurposeRapid 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.MethodsFor 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.ResultsBasal 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.ConclusionThe 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.
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