Lower-Limb Muscle Contractile Properties, Explosive Power and the Subjective Response of Elite Soccer Players to the COVID-19 Lockdown

The present study examined the effects of the lockdown period on basic anthropometric measures, countermovement jumping performance, skeletal muscle contractile properties derived from tensiomyography (TMG), injury incidence, and self-assessed general well-being in elite soccer players. A total of 266 players were assessed before (PRE) and 32 players were reassessed 11 days after (POST) the COVID-19 period. Significant changes in the TMG parameters were observed POST compared to PRE: contraction time (Tc) increased from 6% to 50% in vastus lateralis [VL] (p = 0.009) and biceps femoris [BF] (p < 0.001), respectively; whereas radial displacement (Dm) increased for 19% in BF (p = 0.036) and 17% in VL (p < 0.001), respectively. Jumping performance remained unchanged from PRE to POST In addition, athletes rated the lockdown period as a positive event and felt psychologically better during the lockdown, primarily because they spent more time with family members and friends. Although there were no differences in any of the variables describing lower limb muscle power following the two-month lockdown, the altered contractile properties of the assessed muscles suggest suboptimal conditioning of the football players.

A novel methodology for the synchronous collection and multimodal visualisation of continuous neurocardiovascular and neuromuscular physiological data in adults with long COVID

Reports suggest that adults with post-COVID-19 syndrome or long COVID may be affected by orthostatic intolerance syndromes, with autonomic nervous system dysfunction as a possible causal factor of neurocardiovascular instability (NCVI). Long COVID can also manifest as prolonged fatigue, which may be linked to neuromuscular function impairment (NMFI). The current clinical assessment for NCVI monitors neurocardiovascular performance upon the application of orthostatic stressors such as an active (i.e. self-induced) stand or a passive (tilt table) standing test. Lower limb muscle contractions may be important in orthostatic recovery via the skeletal muscle pump. In this study, adults with long COVID were assessed with a protocol that, in addition to the standard NCVI tests, incorporated simultaneous lower limb muscle monitoring for NMFI assessment. To accomplish such an investigation, a wide range of continuous non-invasive biomedical technologies were employed, including digital artery photoplethysmography for the extraction of cardiovascular signals, near-infrared spectroscopy for the extraction of regional tissue oxygenation in brain and muscle, and electromyography for assessment of timed muscle contractions in the lower limbs. With the novel technique described and exemplified in this paper, we were able to integrate signals from all instruments used in the assessment in a precisely synchronized fashion. We demonstrate that it is possible to visualize the interactions between all different physiological signals during the combined NCVI/NMFI assessment. Multiple counts of evidence were collected, which can capture the dynamics between skeletal muscle contractions and neurocardiovascular responses. The proposed multimodal data visualization can offer an overview of the functioning of the muscle pump during both supine rest and orthostatic recovery and can conduct comparison studies with signals from multiple participants at any given time in the assessment. This could help researchers and clinicians generate and test hypotheses based on the multimodal inspection of raw data, in long COVID and other clinical cohorts.

Grey Relational Analysis of Lower Limb Muscle Fatigue and Pedalling Performance Decline of Elite Athletes during a 30-Second All-Out Sprint Cycling Exercise

The 30-second all-out sprint cycling exercise is a classical sport capacity evaluation method, which may cause severe lower limb muscle fatigue. However, the relationship between lower limb muscle fatigue and the decline in exercise performance during 30-second sprint cycling remains unclear. In this study, ten cyclists volunteered to participate in a 30-second all-out sprint cycling while power, cadence, and surface electromyographic (EMG) signals of eight lower limb muscles were recorded during the exercise. EMG mean frequency (MNF) of each lower limb muscle group was computed for every 3-second epoch based on wavelet packet transformation. Grey relational grades between pedalling performance and the EMG MNF of each lower limb muscle group during the whole process were calculated. The results demonstrated that EMG MNF of the rectus femoris (RF), vastus (VAS), gastrocnemius (GAS), and tibialis anterior (TA) progressively tired during a 30-second all-out sprint cycling exercise. Of the muscles evaluated, the degree of fatigue of TA showed the greatest association with exercise performance decline, whereas the muscle fatigue of RF, VAS, and GAS also significantly impacted exercise performance during a 30-second all-out sprint cycling exercise.

The Effect of Lower-Limb Exercise on Pain Management of the Patients Undergoing Posterior Lumbar Fusion Surgery: A Retrospective Case-Control Study

Purpose. The purpose of this study is to investigate the clinical effect of lower-limb exercise, when combined with celecoxib, on pain management of patients undergoing posterior lumbar fusion surgeries. Methods. The patients undergoing posterior lumbar fusion surgeries between 01/2018 and 06/2021 were retrospectively identified, with their data collected. After surgery, some patients took celecoxib for analgesia (celecoxib group, 200 mg/day) while the others took celecoxib together with lower-limb exercise (combined group, celecoxib-200 mg/day). On postoperative days (POD) 1, 3, 7, and 14, data were collected and analyzed regarding the following items: patient satisfaction, lower-limb muscle force, lumbar JOA score (29 points), Oswestry Disability Index (ODI), and visual analog scale (VAS) score. Results. A total of 225 participants were included in this study. Specifically, 120 cases were admitted into in the celecoxib group and 105 were included in the combined group. Comparisons of baseline data did not indicate any difference between the combined group and the celecoxib group. Data analysis showed that patient satisfaction in the combined group was significantly higher than the celecoxib group on POD 3, 7, and 14, respectively (all p < 0.001 ). Moreover, the combined group had less VAS score compared with the celecoxib group on POD 3, 7, and 14, respectively (all p < 0.01 ). In addition, lower-limb muscle force in the combined group was significantly stronger than that in the celecoxib group on POD 3 and POD 7, respectively (both p < 0.01 ). Furthermore, the combined group achieved less ODI score than the celecoxib group on POD 3, 7, and 14, respectively (all p < 0.05 ). Comparisons of the lumbar JOA score did not suggest any statistical difference during the whole follow-up period. Conclusions. In conclusion, postoperative lower-limb rehabilitation exercise can help to release pain after lumbar fusion surgeries. Additionally, postoperative lower-limb exercise can facilitate the recovery of lower-limb muscle force, as well as improving patient satisfaction.

A Semi-recumbent Eccentric Cycle Ergometer Instrumented to Isolate Lower Limb Muscle Contractions to the Appropriate Phase of the Pedal Cycle

Eccentric (ECC) cycling is used in rehabilitation and sports conditioning settings. We present the construction and mode of operation of a custom-built semi-recumbent ECC cycle designed to limit the production of lower limb muscle activity to the phase of the pedal cycle known to produce ECC contractions. A commercially available semi-recumbent frame and seat (Monarch, 837E Semi-recumbent Bike, Sweden) were used to assemble the ergometer. An electrical drive train system was constructed using individual direct drive servo motors. To avoid active muscle activation occurring during the non-ECC pedaling phase of cycling, a “trip” mechanism was integrated into the drivetrain system using a servo-driven regenerative braking mechanism based on the monitoring of the voltage produced over and above a predetermined threshold produced by the motors. The servo drive internal (DC bus) voltage is recorded and internally monitored during opposing (OPP) and non-opposing (N-OPP) phases of the pedal cycle. To demonstrate that the cycle functions as desired and stops or “trips” when it is supposed to, we present average (of 5 trials) muscle activation patterns of the principal lower limb muscles for regular ECC pedal cycles in comparison with one pedal cycle during which the muscles activated outside the desired phase of the cycle for a sample participant. This semi-recumbent ECC cycle ergometer has the capacity to limit the occurrence of muscle contraction only to the ECC phase of cycling. It can be used to target that mode of muscle contraction more precisely in rehabilitation or training studies.

Characteristics of muscle contraction of the rectus femoris using Tensiomyography by sex in healthy adolescents: a Cross-Sectional Study

Background Tensiomyography (TMG) is a non-invasive instrument for measuring mechanical muscle contraction characteristics, and measures the maximum displacement of the muscle belly in the vertical direction and the time needed to achieve this from electrical stimulation. There have only been few reports of TMG on general healthy adults. A systematic review on TMG reported a low proportion of female participants with a small sample size. Therefore, it is unclear whether there is a difference in TMG parameters by sex and between the dominant and non-dominant feet. Furthermore, the relationship between the TMG parameters and the evaluations commonly used in clinical practice has not been clarified. This study aimed to clarify the characteristics of muscle contraction of the rectus femoris using tensiomyography by sex among healthy adolescents and its relationship with muscle function evaluation, such as lower limb muscle mass and muscle strength. The subjects included 91 healthy university students. The measurement items included TMG, lower limb muscle mass, rectus femoris thickness, isometric knee joint extension torque, and thigh circumference. Results There was a main effect on sex in all parameters (ρ ≤ 0.05). In terms of TMG parameters, maximum displacement (Dm) in the non-dominant foot was significantly lower in women. The correlation between TMG parameters for males and females and lower limb muscle mass, muscle thickness, joint torque, and thigh circumference had a significant correlation with some TMG parameters and lower limb muscle mass (ρ ≤ 0.05). The absolute value of the correlation coefficient was overall low with 0.27 ~0.45. Conclusion In healthy adolescents, there was a difference by sex in TMG parameters and a weak correlation between TMG parameters and the lower limb muscle mass. TMG parameter evaluation may indicate a different function compared with the traditional muscle function assessment used in clinical practice. The TMG parameter is considered as a unique evaluation method for neuromuscular function assessment.

Reliability and validity of hand-held dynamometry for assessing lower limb muscle strength

BACKGROUND: Hand-held dynamometry (HHD) is used to assess muscle strength in various patient populations, but many variations in protocols exist. OBJECTIVE: First, to systematically develop a protocol of HHD for all lower limb muscle groups and evaluate intra-rater reliability; second, to validate HHD with fixed dynamometry for the knee flexor and extensor muscles. METHODS: Thirty healthy young adults (women: men – 15:15) participated in two testing sessions. HHD of 12 lower limb muscle groups was performed in both sessions, while fixed dynamometry of knee muscle groups was performed only in the second session. RESULTS: The intra-rater reliability of HHD was good for five muscle groups and excellent for seven muscle groups (ICC3, k= 0.80–0.96). The criterion validity of HHD ranged from very good to excellent for the knee flexors (r= 0.77–0.89) and from good to very good for the knee extensors (r= 0.65–0.78). However, peak moment values for the knee extensor muscles were underestimated by 32% (p< 0.001). CONCLUSIONS: The proposed HHD protocol provides reliable and valid measurements of lower limb muscle isometric strength in healthy adults, which may also be used to test patients with mild muscle strength deficits. However, possible underestimation of absolute strength must be considered when interpreting the results of knee extensors or other large muscles.