Purpose: To compare the concentric and eccentric training effects on fatigue induced by eccentric and concentric protocols. Methods: A total of 22 men and women (22 [3.6] y) were assigned to concentric (GCON, n = 11) or eccentric training (GECC, n = 11). The concentric (CON) and eccentric (ECC) protocols were composed of 4 sets of 20 knee-extension/flexion repetitions. Force losses were analyzed by comparing 10 repetitions’ mean torques during the protocols and by verifying the maximal voluntary contraction and rate of torque development before and after the protocols. Muscle damage was assessed using echo intensity of the vastus lateralis 48 h after the protocols. Training consisted of 6 wk of isokinetic exercise at 60°/s (concentric or eccentric) twice weekly. Results: Before training, both protocols resulted in dynamic and isometric force losses in GCON and GECC (P < .01), but the magnitude was greater after the CON protocol than after the ECC protocol (P < .001). After training, both GCON and GECC showed similar force decreases during the CON and ECC protocols (P < .01), and these changes were not different from the pretraining decreases. Regarding maximal voluntary contraction after training, GECC showed lower force decreases than GCON after ECC exercise (−13.7% vs −22.3%, respectively, P < .05), whereas GCON showed lower maximal voluntary contraction decreases after CON exercise compared with pretraining (−29.2%, P < .05). Losses in rate of torque development were similar after the protocols before and after the training regimens. No changes in echo intensity were observed after the protocols before and after training. Conclusion: Both interventions resulted in similar force decreases during fatigue protocols compared with those associated with pretraining.
Eduardo Lusa Cadore, Miriam González-Izal, Rafael Grazioli, Igor Setuain, Ronei Silveira Pinto and Mikel Izquierdo
Igor Setuain, Mikel Izquierdo, Fernando Idoate, Eder Bikandi, Esteban M. Gorostiaga, Per Aagaard, Eduardo L. Cadore and Jesús Alfaro-Adrián
The muscular function restoration related to the type of physical rehabilitation followed after anterior cruciate ligament reconstruction (ACLR) using autologous hamstring tendon graft in terms of strength and cross-sectional area (CSA) remain controversial.
To analyze the CSA and force output of quadriceps and hamstring muscles in subjects following either an Objective Criteria-Based Rehabilitation (OCBR) algorithm or the usual care (UCR) for ACL rehabilitation in Spain, before and 1 year after undergoing an ACLR.
Longitudinal clinical double-blinded randomized controlled trial.
Sports-medicine research center.
40 recreational athletes (30 male, 10 female [24 ± 6.9 y, 176.55 ± 6.6 cm, 73.58 ± 12.3 kg]).
Both groups conducted differentiated rehabilitation procedures after ACLR. Those belonging to OCBR group were guided in their recovery according to the current evidence-based principles. UCR group followed the national conventional approach for ACL rehabilitation.
Main Outcome Measures:
Concentric isokinetic knee joint flexor-extension torque assessments at 180°/s and Magnetic Resonance Imaging (MRI) evaluations were performed before and 12 months after ACLR. Anatomical muscle CSA (mm2) was assessed, in Quadriceps, Biceps femoris, Semitendinous, Semimembranosus, and Gracilis muscles at 50% and 70% femur length.
Reduced muscle CSA was observed in both treatment groups for Semitendinosus and Gracilis 1 year after ACLR. At 1-year follow-up, subjects allocated to the OCBR demonstrated greater knee flexor and extensor peak torque values in their reconstructed limbs in comparison with patients treated by UCR.
Objective atrophy of Semitendinosus and Gracilis muscles related to surgical ACLR was found to persist in both rehabilitation groups. However, OCBR after ACLR lead to substantial gains on maximal knee flexor strength and ensured more symmetrical anterior-posterior laxity levels at the knee joint.