Muscle Contractile Properties Measured at Submaximal Electrical Amplitudes and Not at Supramaximal Amplitudes Are Associated with Repeated Sprint Performance and Fatigue Markers

Background: The present study analyzes the associations between the muscle contractile properties (MCP) measured at different neuromuscular electrical stimulation amplitudes (NMESa) and the performance or transient fatigue after a bout of repeated sprints. Methods: Seventeen physically active male subjects performed six repeated sprints of 30 m with 30 s of passive recovery. Capillary blood creatine kinase (CK) concentration, knee extension or flexion isometric peak torque, tensiomyography, and repeated sprint performance were assessed. Results: Muscle displacement and contraction time were different in relation to the NMESa used in the rectus femoris and biceps femoris muscles. At rest, significant (p < 0.05) associations were found between muscle displacement and the loss of time in the repeated sprints (sprint performance) at 20 or 40 mA in the rectus femoris. At post +24 h or +48 h, the highest significant associations were found between the muscle displacement or the contraction time and CK or peak torques also at submaximal amplitudes (20 mA). The NMESa which elicits the peak muscle displacement showed lack of practical significance. Conclusion: Although MCP are typically assessed in tensiomyography using the NMESa that elicit peak muscle displacement, a submaximal NMESa may have a higher potential practical application to assess neuromuscular fatigue in response to repeated sprints.

Carbetocin versus Oxytocin in Active Management of 3rd stage of Labour following Vaginal Delivery

Background: Every day more than 220 women around the world die from severe bleeding after childbirth. Globally post-partum hemorrhage is the number one direct cause of maternal mortality. Most postpartum hemorrhages are caused by uterine atony and occur in the immediate postpartum period. Most of these tragic deaths can be prevented by active management of third stage of labour. Active management of the third stage of labor should be practiced routinely to decrease the risk of postpartum hemorrhage. Oxytocin is used for enhancing uterine contraction after delivery. But oxytocin has some limitations like shorter half- life, less contraction time and more side effects, whereas carbetocin has prolonged duration of action which ensures more contraction time and less adverse effects. This study was done to see the efficacy and safety of carbetocin over oxytocin for prevention of PPH after vaginal delivery. Methodology: A randomized controlled clinical trial was conducted in the Department of Obstetrics and Gynecology, Shaheed Suhrawardy Medical College and Hospital, Dhaka, Bangladesh over a period of 9 months from January 2015 to September 2015. Ninety four patients undergoing vaginal delivery at term were randomized into two groups receiving either 10IU oxytocin or 100 μg carbetocin. Outcome measures such as primary PPH, massive blood loss, need for additional uterotonic drug, additional blood transfusion as well as adverse effects were documented. Results: In this study, massive blood loss did not occur none of patients in carbetocin group. But massive blood loss occured 6.4% women of oxytocin group. Further fundal massage , immediate blood transfusion and additional uterotonics didn’t need any patient in carbetocin group. In oxytocin group, fundal massage required in 8.5% of women, blood transfusion needed in 10.6% patients and additional uterotonics needed in 10.6% women. Average amount of blood loss was 88 ml less in carbetocin group and adverse effects of drugs were almost similar in both group. Primary PPH developed in oxytocin group 8.5% but none of patients had developed PPH in carbetocin group. Conclusion: Carbetocin is an effective new drug than oxytocin for prevention of postpartum hemorrhage in vaginal delivery. Bioresearch Commu. 7(1): 927-931, 2021 (January)

Tensiomyographic Neuromuscular Response of the Peroneus Longus and Tibialis Anterior with Chronic Ankle Instability

This study aimed to investigate the muscle contractile response of the peroneus longus (PL) and tibialis anterior (TA) in groups with and without chronic ankle instability (CAI) using tensiomyography. Twenty-three adults, 12 with CAI and 11 healthy participants, participated in this study. All subjects underwent a tensiomyographic assessment of the PL and TA to measure delay time, contraction time and maximal displacement. The ankle evertor and invertor normalized peak torques, maximum work done and muscle thickness of the PL and TA were calculated. The delay time and contraction time of the PL in the CAI side were significantly higher than those in the healthy group (p < 0.05); however, no significant difference could be detected in the TA between groups. Furthermore, there was no significant difference in the normalized peak torques, maximum work done and muscle thickness of the PL and TA between groups. The CAI side demonstrated a delayed muscle contractile response of the PL when compared with the healthy group although there was no difference in muscle strength and muscle size. Clinicians should consider the muscle contractile response of the PL for rehabilitation of the ankle evertor with CAI.

Aerobic exercise training reduces cardiac function and coronary flow-induced vasodilation in mice lacking adiponectin

We tested the hypothesis that adiponectin deficiency attenuates coronary microvascular and cardiac function and prevents exercise training-induced adaptations of the coronary microvasculature and the myocardium in adult mice. Adult wild-type (WT) or adiponectin knockout (adiponectin KO) mice underwent treadmill exercise training or remained sedentary for 8-10 weeks. Systolic and diastolic function were assessed before and after exercise training or cage confinement. Vasoreactivity of coronary resistance arteries was assessed at the end of exercise training or cage confinement. Before exercise training, ejection fraction and fractional shortening were similar in adiponectin KO and WT mice, but isovolumic contraction time was significantly lengthened in adiponectin KO mice. Exercise training increased ejection fraction (12%) and fractional shortening (20%) with no change in isovolumic contraction time in WT mice. In adiponectin KO mice, both ejection fraction (-9%) and fractional shortening (-12%) were reduced after exercise training, and these decreases were coupled to a further increase in isovolumic contraction time (20%). In sedentary mice, endothelium-dependent dilation to flow was higher in arterioles from adiponectin KO mice as compared to WT mice. Exercise training enhanced dilation to flow in WT mice, but decreased flow-induced dilation in adiponectin KO mice. These data suggest that compensatory mechanisms contribute to the maintenance of microvascular and cardiac function in sedentary mice lacking adiponectin; however, in the absence of adiponectin, coronary microvascular and cardiac adaptations to exercise training are compromised.

Effects of a Massage Protocol in Tensiomyographic and Myotonometric Proprieties

Background: Pre-competition massage is usually used to improve athletic performance and reduce risk of injury. Despite its usual use, the effects of pre-competition massage on neuromuscular function have barely been studied. The aim of this study is to evaluate the effects of the pre-competition massage over the gastrocnemius neuromuscular function. Method: The study is a quasi-experimental clinical trial thirty healthy athletes were enrolled in the study. Subjects received an intervention in one leg (experimental), consisting of a massage, and no intervention in the opposite leg (control). From all values of neuromuscular function, the following were analyzed: contraction time (Tc) and maximal displacement (Dm) by tensiomyography, and stiffness and tone by myotonometry. Results: Main effects of pre-competition massage on neuromuscular function include a significant (p < 0.05) increase in Tc and Dm variables, as well as a reduction in stiffness and tone. Conclusion: Data shows an increase in Tc and maximal radial displacement (Dm) variables, as well as a reduction in stiffness and tone. More quality studies are needed to draw clear conclusions about the effects of pre-competition massage.

Caffeine-Induced Effects on Human Skeletal Muscle Contraction Time and Maximal Displacement Measured by Tensiomyography

Studies on muscle activation time in sport after caffeine supplementation confirmed the effectiveness of caffeine. The novel approach was to determine whether a dose of 9 mg/kg/ body mass (b.m.) of caffeine affects the changes of contraction time and the displacement of electrically stimulated muscle (gastrocnemius medialis) in professional athletes who regularly consume products rich in caffeine and do not comply with the caffeine discontinuation period requirements. The study included 40 professional male handball players (age = 23.13 ± 3.51, b.m. = 93.51 ± 15.70 kg, height 191 ± 7.72, BMI = 25.89 ± 3.10). The analysis showed that in the experimental group the values of examined parameters were significantly reduced (p ≤ 0.001) (contraction time: before = 20.60 ± 2.58 ms/ after = 18.43 ± 3.05 ms; maximal displacement: before = 2.32 ± 0.80 mm/after = 1.69 ± 0.51 mm). No significant changes were found in the placebo group. The main achievement of this research was to demonstrate that caffeine at a dose of 9 mg/kg in professional athletes who regularly consume products rich in caffeine has a direct positive effect on the mechanical activity of skeletal muscle stimulated by an electric pulse.

Comparison of Interventional Strategies to Improve Recovery after Eccentric Exercise-Induced Muscle Fatigue

The aim of this study was to compare the effects of various recovery techniques on muscle tissue after eccentric exercise-induced muscle fatigue (EIMF). Forty subjects (24.3 ± 2.6 years; 77.45 ± 8.3 kg; 177.0 ± 6.4 cm; 24.66 ± 1.6 kg∙m−2) were randomly assigned to one of the following groups: manual therapy (n =10, MT), mechanical vibration (n = 10, MV), percussion therapy (n = 10, PT) or foam roller (n = 10, FR). The contraction time (Tc) and the radial displacement (Dm) of the gastrocnemius was evaluated through tensiomyography (TMG). The application of the different techniques had positive effects for Tc and Dm in the treated leg compared to the untreated leg (F = 50.01, p < 0.01, η2p = 0.58 and F = 27.58, p < 0.01, η2p = 0.43, respectively) and for the interaction of the factors (Time x Leg x Therapy: F = 5.76, p < 0.01, η2p = 0.32 and F = 5.93, p < 0.01, η2p = 0.33, respectively). The results of the various methods used were similar: Tc (F = 0.17, p = 0.917; η2p = 0.01) and Dm (F = 3.30, p = 0.031, η2p = 0.22). PT interventions show potential for restoring muscle compliance and reducing stiffness, similar to MT and possibly more effective (cost-time relationship) compared to MV or FR.

Effects of Kinesio Taping on Muscle Contractile Properties: Assessment Using Tensiomyography

Context: Although functional effects of kinesio taping (KT) have been widely studied, its effects on contractile properties of the target muscle remain unclear. Tensiomyography is suitable for quantifying muscle stiffness and rate of force development upon imposed twitch contraction. Objective: To test the hypothesis that KT has effects on contractile properties of targeted muscle using tensiomyography. Design: Prospective cohort study. Settings: Performance laboratory of a sports rehabilitation center. Participants: A total of 11 healthy volunteers. Interventions: Tensiomyography measurements before KT facilitation technique applied (pre-KT), 45 minutes, and 24 hours after KT (post-KT1 and post-KT2, respectively) without removing the tape. Main Outcome Measures: Maximal radial displacement, contraction time, delay time, sustain time, relaxation time, and velocity of contraction. Results: Significant effects were shown for maximal radial displacement (P = .004), contraction time (P = .013), relaxation time (P = .035), and velocity of contraction (P = .0033), but not for delay time (P = .060) and sustain time (P = .078). Post hoc testing indicated a significant decrease in maximal radial displacement for post-KT1 only (from 6.33 [1.46] to 4.87 [2.14] mm), and a significant increase in contraction time for both post-KT1 and post-KT2 (from 30.87 [11.39] to 39.71 [13.49] ms, and 37.41 [14.73] ms, respectively). Post hoc testing also showed a significant decrease in relaxation time for post-KT2 (from 65.97 [53.43] to 47.45 [38.12] ms), and a significant decrease in velocity of contraction for both post-KT1 and post-KT2 (from 0.22 [0.08] to 0.15 [0.09] mm/s, and 0.16 [0.07] mm/s), respectively. Conclusion: The findings indicate that KT leads to an increased muscle stiffness and a reduced muscle rate of force production despite the facilitation technique applied.

Acute Effects of Tissue Flossing on Ankle Range of Motion and Tensiomyography Parameters

Context: Recently, a few papers have suggested that tissue flossing (TF) acutely improves range of motion (ROM) and neuromuscular performance. However, the effects of TF on muscle contractile properties are yet to be defined. Objective: To investigate the acute effects of TF on ankle ROM and associated muscle gastrocnemius medialis displacement and contraction time assessed with tensiomyography. Design: Crossover design in a single session. Setting: University laboratory. Participants: Thirty recreationally trained volunteers (age 23.00 [4.51] y). Intervention: Active ankle plantar flexion and dorsiflexion were performed for the duration of 2 minutes (3 sets, 2-min rest between sets), while a randomly selected ankle was wrapped using TF elastic band (BAND) and the other ankle served as a control condition (CON). Main Outcome Measures: Participants performed an active ankle plantar flexion and dorsiflexion ROM test and muscle gastrocnemius medialis tensiomyography displacement and contraction time measurement pre, 5, 15, 30, and 45 minutes after the floss band application. Results: There were no statistically significant differences between BAND and CON conditions (active ankle plantar flexion ROM: P = .09; active ankle dorsiflexion ROM: P = .85); however, all ROM measurements were associated with medium or large effect sizes in favor of BAND compared with CON. No significant changes were observed in the tensiomyography parameters. Conclusions: The results of this study suggest that TF applied to the ankle is a valid method to increase ROM and at the same time maintaining muscular stiffness.