An Improved EMG-Driven Neuromusculoskeletal Model for Elbow Joint Muscle Torque Estimation

The accurate measurement of human joint torque is one of the research hotspots in the field of biomechanics. However, due to the complexity of human structure and muscle coordination in the process of movement, it is difficult to measure the torque of human joints in vivo directly. Based on the traditional elbow double-muscle musculoskeletal model, an improved elbow neuromusculoskeletal model is proposed to predict elbow muscle torque in this paper. The number of muscles in the improved model is more complete, and the geometric model is more in line with the physiological structure of the elbow. The simulation results show that the prediction results of the model are more accurate than those of the traditional double-muscle model. Compared with the elbow muscle torque simulated by OpenSim software, the Pearson correlation coefficient of the two shows a very strong correlation. One-way analysis of variance (ANOVA) showed no significant difference, indicating that the improved elbow neuromusculoskeletal model established in this paper can well predict elbow muscle torque.

The Effect of Cryotherapy on Proprioception and Knee Extensor Torque in Healthy Volunteers

Objectives: This study was done to investigate the influences of cryotherapy on the joint position sense (JPS) and extensor muscles torque of the knee. Methods: Forty healthy volunteers (20 men, 20 women; age range, 21 – 30 y) participated. Two cooling pads were applied to the knee and anterior thigh for 15 minutes at 4°C. The accuracy of the knee JPS was evaluated before and after cooling in two angles, including 45° and 60° flexion. Extensor muscles torque of the knee was obtained in two velocities of 30°/s and 120°/s. Results: The effect of time and the interaction between the group and time were not significant for both active and passive repositioning error tests of the knee joint angles (P ≥ 0.05). The knee extensor's muscle torque increased significantly during both velocities of 30°/s and 120°/s, immediately and 30 minutes after the cryotherapy in the experimental group (P ≤ 0.01). Cooling for 15 minutes made a higher knee extensor muscle torque and did not change the JPS. Conclusions: These findings should be considered for therapeutic programs that involve exercise immediately after a period of cryotherapy.

The Effects of Age and Body Fat Content on Post-Downhill Run Recovery Following Whole Body Cryotherapy

This study explored the effects of age and body fat content on responses to whole body cryotherapy (WBC) following a downhill running bout. Forty-one male participants (mean ± SD age 42.0 ± 13.7 years, body mass 75.2 ± 10.8 kg) were allocated into WBC (n = 26) and control (CON, n = 15) groups. WBC participants were divided into old (OLD, ≥45 years, n = 10) and young (YNG, <40 years, n = 13), as well as high fat (HFAT, ≥20%, n = 10) and low fat (LFAT ≤ 15%, n = 8) groups. Participants completed a 30 min downhill run (15% gradient) at 60% VO2 max. The WBC group underwent cryotherapy (3 min, −120 °C) 1 h post-run and CON participants passively recovered in a controlled environment (20 °C). Maximal isometric leg muscle torque was assessed pre and 24 h post-run. Blood creatine kinase (CK) and muscle soreness were assessed pre, post, one hour and 24 h post-run. Muscle torque significantly decreased in both groups post-downhill run (WBC: 220.6 ± 61.4 Nm vs. 208.3 ± 67.6 Nm, p = 0.02; CON: 239.7 ± 51.1 Nm vs. 212.1 ± 46.3 Nm, p = 0.00). The mean decrease in WBC was significantly less than in CON (p = 0.04). Soreness and CK increased 24 h post for WBC and CON (p < 0.01) with no difference between groups. Muscle torque significantly decreased in OLD participants (p = 0.04) but not in YNG (p = 0.55). There were no differences between HFAT and LFAT (all p values > 0.05). WBC may attenuate muscle damage and benefit muscle strength recovery following eccentrically biased exercises, particularly for young males.

Addition of aerobic training to conventional rehabilitation after hip fracture: a randomized, controlled, pilot feasibility study

Objectives: To determine the feasibility and safety of aerobic training with an arm crank ergometer and its effectiveness in improving functional capacity and gait in patients with recent hip fracture. Design: Randomized, controlled, assessor-blinded pilot study, with intention-to-treat analysis. Setting: Inpatients, rehabilitation department. Subjects: 40 patients with hip fracture surgically treated. Interventions: Training group performed aerobic exercise with an arm crank ergometer (15 sessions, 30 minutes/day) at an intensity of 64% to 76% of maximum heart rate, in addition to conventional inpatient rehabilitation. Main measures: Primary outcome was the feasibility (including eligibility rate, recruitment rate, number of drop-outs and adverse events, adherence). Secondary measures were the Timed Up and Go test, ability to walk independently, muscle torque of knee extensors of fractured and non-fractured leg, Functional Independence Measure. Results: Mostly due to pre-existing disability and fracture type, only 40/301 (13%) patients were eligible (age 84.6 ± 7.6 years, 75% female); all agreed to participate and 90% completed the trial, without adverse events. Adherence to aerobic exercise was good, with high attendance at sessions (93%), a strong compliance to exercise duration (95%) but lower compliance to the prescribed intensity (73%). After the program, more patients were able to walk independently in the training group ( n = 18) compared to control ( n = 13) ( P < 0.05). Also the muscle torque of fractured leg knee extensors was higher in the training group ( P < 0.05). Conclusion: Aerobic training in addition to conventional rehabilitation after a hip fracture is feasible and safe and it was effective in improving gait performance and strength of fractured leg. Trial registration: NCT04025866.