Should We Trust Perceived Effort for Loading Control and Resistance Exercise Prescription After ACL Reconstruction?

CONTEXT: The rating of perceived effort (RPE) is a common method used in clinical practice for monitoring, loading control, and resistance training prescription during rehabilitation after rupture and anterior cruciate ligament reconstruction (ACLR). It is suggested that the RPE results from the integration of the afferent feedback and corollary discharge in the motor and somatosensory cortex, and from the activation of brain areas related to emotions, affect, memory, and pain (eg, posterior cingulate cortex, precuneus, and prefrontal cortex). Recent studies have shown that rupture and ACLR induce neural adaptations in the brain commonly associated with the RPE. Therefore, we hypothesize that RPE could be affected because of neural adaptations induced by rupture and ACLR. STUDY DESIGN: Clinical review. LEVEL OF EVIDENCE: Level 5. RESULTS: RPE could be directly altered by changes in the activation of motor cortex, posterior cingulate cortex, and prefrontal cortex. These neural adaptations may be induced by indirect mechanisms, such as the afferent feedback deficit, pain, and fear of movement (kinesiophobia) that patients may feel after rupture and ACLR. CONCLUSION: Using only RPE for monitoring, loading control, and resistance training prescription in patients who had undergone ACLR could lead to under- or overdosing resistance exercise, and therefore, impair the rehabilitation process. STRENGTH-OF-RECOMMENDATION TAXONOMY: 3C.

Effects of Individualized Ischemic Preconditioning on Protection Against Eccentric Exercise-Induced Muscle Damage: A Randomized Controlled Trial.

BACKGROUND: The effects of ischemic preconditioning (IPC) versus a deceptive sham protocol on indirect markers of exercise-induced muscle damage (EIMD) after the application of individualized occlusion pressure were examined. The goal of using a sham protocol is to control for the potential effect of placebo. HYPOTHESIS: IPC would surpass the sham protocol in protecting against EIMD. STUDY DESIGN: A randomized, double-blinded, clinical trial. LEVEL OF EVIDENCE: Level 1. METHODS: Thirty healthy young men were randomly assigned to an eccentric exercise for the knee extensor muscles preceded by IPC (4 × 5 minutes of individualized total occlusion pressure) or sham protocol (4 × 5 minutes using 20 mm Hg). Maximal voluntary isometric torque (MVIT), rate of torque development, muscle soreness, pressure pain threshold, knee range of motion, thigh girth, and creatine kinase (CK) activity were assessed before IPC or sham protocol and up to 72 hours after the eccentric EIMD. Affective valence and perceived exertion were also evaluated. RESULTS: MVIT decreased 17.1% in the IPC and 18.1% in the sham groups, with no differences between groups. Differences from baseline were observed in the sham group for muscle soreness at 48 hours (P < 0.001) and 72 hours (P = 0.02), and for CK activity at 72 hours (P = 0.04). Muscle soreness was reduced in the IPC group at 48 hours compared with the sham group (∆ = 15.8 mm; P = 0.008) but without achieving the minimal clinically important difference. IPC induced a smaller perceived exertion than the sham protocol (∆ = 1.1 a.u.; P = 0.02). The remaining outcomes were not statistically different in both groups. CONCLUSION: IPC does not surpass the sham protocol to protect against mild EIMD of the knee extensors muscles. CLINICAL RELEVANCE: Although IPC is a noninvasive, low-cost, and easy-to-administer intervention, the IPC effects can, in part, be explained by the placebo effect. In addition, individualized IPC promotes attenuation in perceived exertion during eccentric exercise.

Upper limbs total occlusion pressure assessment: Doppler ultrasound reproducibility and determination of predictive variables.

Total occlusion pressure (TOP) is an important variable to ischaemic exercise training because the optimal pressure of flow restriction (OPR), applied during this exercise modality, is derived from it. Despite the common use of Doppler ultrasound (DU) to determine the TOP, the reproducibility of this assessment was not evaluated yet. Given this, the objective was to evaluate the reproducibility of DU for the measurement of TOP in upper limbs and determine the predictive variables. Thirteen male volunteers attended three times to the laboratory. On the 1st day, we assessed arm circumference (AC), systolic blood pressure (SBP) and diastolic (DBP), and brachial artery TOP. On 2nd and 3rd days, only TOP was assessed. We found a coefficient of variation of 5·6% and an intraclass correlation coefficient of 0·795 for the DU. In the analysis of TOP predictive variables, the Spearman coefficients (R) were 0·813 (SBP), 0·786 (DBP) and 0·388 (AC). Therefore, these results support that DU has good reproducibility for the TOP and that SBP and DBP should be considered to the determination of TOP in upper limbs.