Assessment of metabolic response and functional changes after anterior cruciate ligament surgery

The main purpose of this study was to investigate metabolic changes after anterior cruciate ligament reconstruction and to find out whether the statements on training intensity in the literature can also be applied to patients in rehabilitation. Twenty-four male patients, 16 wk (range: 11-21 wk) postoperative, volunteered to participate in the study. A new four-stage test with constant time and load increments on the legpress in the closed kinetic chain (CKC) was performed. Evaluative variables were the aerobic and anaerobic threshold, force at exhaustion, and the maximum strength. Besides the four-stage test, the other parameters evaluated were functional tests (one-legged single hop, one-legged triple hop), rating scales (Lysholm, subjective feeling scale), thigh circumference, peak torque (PT), work and explosive force in the open kinetic chain (OKC), and muscle activity via electromyographic examination. Positive correlations were established for the maximum force in the CKC and PT (P < 0.01) and maximum force in the CKC and the thigh circumference (P < 0.05). The Lysholm score correlated with the anaerobic threshold (P < 0.05) and with the functional tests (P < 0.01). Further correlations were established between the PT and the work (P < 0.05) and between the single hop and the triple hop (P < 0.001). While the maximum force of the uninvolved leg was significantly higher than that of the involved leg (P < 0.01), the forces measured at termination and at the aerobic and anaerobic threshold (given as percent of maximum force) were significantly higher in the involved leg (P < 0.01). It seems that the oxidative potential increases or remains constant in this phase of rehabilitation and therefore the intensity of strength training must be adapted to the needs of the patient. Our easy-to-perform method makes it possible to establish an optimal intensity of training.