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Background:During competition, high-performance swimmers are subject to repeated physical demands that affect their final performance. Measurement of lactate concentration in blood seeks to indirectly gauge physiologic responses to the increase in physical exercise. Swimmers face multiple maximal-exertion events during competition. Strenuous physical exercise leads to fatigue and, thus, a decrease in sports performance.Hypothesis:Regeneration exercises in swimming increase the clearance of blood lactate and therefore improve athletic performance within a single day of competition.Study Design:Crossover study.Level of Evidence:Level 1.Methods:Of 25 swimmers, 21 were included, with a mean age of 17 years. They performed exercises that increased blood lactate on 2 days. The protocol was a warm-up, followed by a 100-m freestyle workout at full speed. Swimming exercises followed that were increasingly demanding, during which serial lactatemia measurements were taken. On the first day, regeneration exercises were performed; on the second day, the swimmers rested. Next, lactatemia was measured, and a timed 100-m freestyle workout was performed at maximum speed.Results:The stress exercises increased the mean lactate concentration by 4.6 mmol/L, which corresponds to 78% of the initial basal level. The postregeneration lactatemia level was lower than that after resting (mean, 2.76 vs 6.51 mmol/L). The time to swim 100 m after regeneration was 68.11 seconds, while that after rest was 69.31 seconds.Conclusion:Blood lactate levels rose by up to 78% after the intensity of the training sessions was progressively increased. Regeneration exercises increased the rate in which blood lactate dissipated, in comparison with passive recuperation. The rate of lactate dissipation for regeneration exercises was 68%. This factor may have improved the physical performance of swimmers.Clinical Relevance:Regeneration exercises improved the performance of swimmers in maximal-exertion competition in a single day. The blood lactate level correlated with physical exercise load.

The purpose of this study was to compare the efficacy of periarticular infiltration of gonyautoxin 2/3 (GTX 2/3) and a mixture of levobupivacaine, ketorolac, and epinephrine for pain management after total knee arthroplasty (TKA). Forty-eight patients were randomly allocated to receive periarticular infiltration of 40 µg GTX 2/3 (n = 24) diluted in 30 mL of sodium chloride 0.9% (study group) or a combination of 300 mg of levobupivacaine, 1 mg of epinephrine, and 60 mg ketorolac (n = 24) diluted in 150 mL of sodium chloride 0.9% (control group). Intraoperative anesthetic and surgical techniques were identical for both groups. Postoperatively, all patients received patient-controlled analgesia (morphine bolus of 1 mg; lockout interval of 8 minutes), acetaminophen, and ketoprofen for 72 hours. A blinded investigator recorded morphine consumption, which was the primary outcome. Also, the range of motion (ROM) and static and dynamic pain were assessed at 6, 12, 36, and 60 hours after surgery. The incidence of adverse events, time to readiness for discharge, and length of hospital stay were also recorded. The median of total cumulative morphine consumption was 16 mg (range, 0–62 mg) in the GTX 2/3 group and 9 mg (range, 0–54 mg) in control group, which did not reach statistical difference (median test, p = 0.40). Furthermore, static and dynamic pain scores were similar at all time intervals. GTX 2/3 was inferior in range of motion at 6 and 12 hours; nevertheless, we noted no difference after 36 hours. No differences between groups were found in terms of complications, side effects, or length of hospital stay. No significant differences were found between groups in terms of breakthrough morphine requirement. However, local anesthetic use resulted in an increased ROM in the first 12 hours. This prospective randomized clinical trial shows that GTX 2/3 is a safe and efficient drug for pain control after TKA; nevertheless, more studies using GTX 2/3 with larger populations are needed to confirm the safety profile and efficiency. This is level 1 therapeutic study, randomized, double-blind clinical trial.

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