Recovery and Fatigue Behavior of Forearm Muscles during a Repetitive Power Grip Gesture in Racing Motorcycle Riders

Despite a reduction in the maximal voluntary isometric contraction (MVCisom) observed systematically in intermittent fatigue protocols (IFP), decrements of the median frequency, assessed by surface electromyography (sEMG), has not been consistently verified. This study aimed to determine whether recovery periods of 60 s were too long to induce a reduction in the normalized median frequency (MFEMG) of the flexor digitorum superficialis and carpi radialis muscles. Twenty-one road racing motorcycle riders performed an IFP that simulated the posture and braking gesture on a motorcycle. The MVCisom was reduced by 53% (p < 0.001). A positive and significant relationship (p < 0.005) was found between MFEMG and duration of the fatiguing task when 5 s contractions at 30% MVCisom were interspersed by 5 s recovery in both muscles. In contrast, no relationship was found (p > 0.133) when 10 s contractions at 50% MVC were interspersed by 1 min recovery. Comparative analysis of variance (ANOVA) confirmed a decrement of MFEMG in the IFP at 30% MVCisom including short recovery periods with a duty cycle of 100% (5 s/5 s = 1), whereas no differences were observed in the IFP at 50% MVCisom and longer recovery periods, with a duty cycle of 16%. These findings show that recovery periods during IFP are more relevant than the intensity of MVCisom. Thus, we recommend the use of short recovery periods between 5 and 10 s after submaximal muscle contractions for specific forearm muscle training and testing purposes in motorcycle riders.

Behavioral effects of continuous theta-burst stimulation in macaque parietal cortex

The neural mechanisms underlying the effects of continuous Theta-Burst Stimulation (cTBS) in humans are poorly understood. Animal studies can clarify the effects of cTBS on individual neurons, but behavioral evidence is necessary to demonstrate the validity of the animal model. We investigated the behavioral effect of cTBS applied over parietal cortex in rhesus monkeys performing a visually-guided grasping task with two differently sized objects, which required either a power grip or a pad-to-side grip. We used Fitts’ law, predicting shorter grasping times (GT) for large compared to small objects, to investigate cTBS effects on two different grip types. cTBS induced long-lasting object-specific and dose-dependent changes in GT that remained present for up to two hours. High-intensity cTBS increased GTs for a power grip, but shortened GTs for a pad-to-side grip. Thus, high-intensity stimulation strongly reduced the natural GT difference between objects (i.e. the Fitts’ law effect). In contrast, low-intensity cTBS induced the opposite effects on GT. Modifying the coil orientation from the standard 45-degree to a 30-degree angle induced opposite cTBS effects on GT. These findings represent behavioral evidence for the validity of the nonhuman primate model to study the neural underpinnings of non-invasive brain stimulation.

THE CORRELATION OF HAND GRIP STRENGHT WITH FOREARM AND HAND ANTHROPOMETRY AND BODY MASS INDEX

Introduction: An individual’s overall muscle strength is commonly assessed by a power grip measurement, a reliable indicator of functional capacity and physical condition. The development of muscle parallels the changes of body composition during growth. Aim of this study is to examine the correlationship between hand grip strength and anthropometric. Methods: This cross-sectional study involved 76 male students of Dhammasavana School, aged between 12 – 16 years old, North Jakarta. Hand grip strength was examined using a digital dynamometer on the dominant side. Statistical analysis was computed using SPSS ver. 15.0 program with Spearman correlations test. Significance was set at p<0.05. Results: Dominant hand grip strength was found to have significant (p<0.05 - 0.001) positive correlation with height (r=0.612), lower arm muscle-and-bone cross-sectional circumference and area (CSA) (r=0.553 and r=0.553 respectively), hand length (r=0.548), forearm length (r=0.540), age (r=0.520), weight (r=0.416), and forearm girth (r=0.376). Conclusion: No significant correlation between grip strength and body mass index was found. Positive correlations between the variables mentioned above conclude that the higher the value of the anthropometric measurements, the greater the strength generated in a power grip.

Management of Flexor Pollicis Longus Injury - Experience in BSMMU

Anatomic consideration: Flexor pollicis longus (FPL) tendon arises from volar aspect of middle third of radial shaft and from the lateral aspect of interosseous membrane. The anterior interosseous branch of median nerve innervates the muscle in the proximal/mid forearm. Blood supply is predominantly from radial artery. Abstract Purpose: The purpose of this study was to evaluate the results of repair and one stage reconstruction of FPL injury and to find out complications and rupture rate and effectiveness of repair and reconstruction. Method: This retrospective review was carried out in Bangabandhu Sheikh Mujib Medical University from January 2015 to December 2018. 30 consecutive patients were enrolled in the study. 4 strands core suture with simple circumferential suture were used for repair and reconstruction. Tendon transfer was done in few cases. Power grip, active and passive range of motion, American Society for Surgery of the Hand criteria and Buck-Gramcko criteria were used for outcome assessment. Results: Out of 30 patients, 20 (67%) were male and 10 (33%) were female. Mean age was 30 years. Mean follow up period was 1.5 years. All cases were due to various type of cut injuries. In subjective assessment 40% patients achieved excellent, 50% good, 10% fair results. Our rupture rate was 0%. Mean power grip, pinch grip strength of index and key pinch strength were 87.5%, 68.18% and 86.66% respectively from contralateral normal hand. Active range of motion of IP joint was 64.28% of normal side. Conclusions: Use of 4 strands core sutures and early active motion give good to excellent results in 90% cases of repair, reconstruction and tendon transfer in FPL injuries with 0% rupture rate J Shaheed Suhrawardy Med Coll, December 2020, Vol.12(1); 20-26

Flexor digitorum profundus with or without flexor digitorum superficialis tendon repair in acute Zone 2B injuries

A total of 53 patients with complete cuts of two flexor tendons in Zone 2B treated over a 9-year period was reviewed. Twenty-three patients (28 fingers) had only flexor digitorum profundus repair, while 30 patients (36 fingers) had both flexor digitorum profundus and flexor digitorum superficialis repairs, with a mean follow-up of 21 months (range 12–84). The decision to repair the flexor digitorum superficialis was made according to intraoperative judgement of ease of repair and gliding of the flexor digitorum profundus tendon. Two groups of patients showed no significant differences in total range of active or passive digital motion and power grip percentage to the contralateral hand. However, the values of power grip were statistically superior in the patients with both tendons repaired. The patients after flexor digitorum profundus-only repairs showed significantly greater but still mild flexion contracture (mean 20 °) of the operated digits. The Tang gradings were the same with 89% good and excellent rates in both groups. The conclusion is that although repair of both flexor digitorum profundus and flexor digitorum superficialis tendons is slightly more preferable based on increased grip strength, the repair of the flexor digitorum superficialis together with flexor digitorum profundus is not mandatory. Whether or not to repair flexor digitorum superficialis is an intraoperative decision based on the ease of gliding of the repaired tendon(s). Level of evidence: III

Analysis of Different Hand and Finger Grip Patterns using Surface Electromyography and Hand Dynamometry

Recording an Electromyogram (EMG) signal is essential for diagnostic procedures like muscle health assessment and motor neurons control. The EMG signals have been used as a source of control for powered prosthetics to support people to accomplish their activities of daily living (ADLs). This work deals with studying different types of hand grips and finding their relationship with EMG activity. Five subjects carried out four functional movements (fine pinch, tripod grip and grip with the middle and thumb finger, as well as the power grip). Hand dynamometer has been used to record the EMG activity from three muscles namely; Flexor Carpi Radialis (FCR), Flexor Digitorum Superficialis (FDS), and Abductor Pollicis Brevis (ABP) with different levels of Maximum Voluntary Contraction (MVC) (10-100%). In order to analyze the collected EMG and force data, the mean absolute value of each trial is calculated followed by a calculation of the average of the 3 trials for each grip for each subject across the different MVC levels utilized in the study. Then, the mean and the standard deviation (SD) across all participants (3 males and 2 females) are calculated for FCR, FDS and APB muscles with multiple % MVC, i.e 10, 30, 50, 70 % MVC for each gesture. The results showed that APB muscle has the highest mean EMG activity across all grips, followed by FCR muscle. Furthermore, the grip with the thumb and middle fingers is the grip with the highest EMG activity for 10-70% MVC than the power grip. As for the 100% MVC, thumb and middle fingers grip achieved the highest EMG activity for APB muscle, while the power grip has the highest EMG activity for both FCR and FDS muscles.

Trigger Finger From Ocean Rowing: An Observational Study

Background: Trigger finger has a prevalence of 2% to 3% in the general population. Although anecdotal evidence exists, there is a lack of conclusive data that prove a relationship between repetitive power grip and flexion with triggering. Ocean rowing is becoming a popular sport, with the race across the Atlantic alone attracting more than 100 participants annually. Anecdotal reports suggest ocean rowing may be a significant cause of trigger finger. We aimed to identify whether the sport causes an increased prevalence of triggering, whether there were any alleviating or compounding factors, and, finally, whether there was any effect on performance. Methods: A prospective observational study was carried out. A questionnaire was sent to all participants of the Talisker Whisky Atlantic Challenge 2018, which included a trigger finger self-scoring system and the Oslo Sports Trauma Center Overuse Injury Questionnaire. Results: Responses were received from 67 rowers (83% response rate). Age ranged from 21 to 62 years, with a mean of 40 years. In all, 49.3% had clinical triggering, with 79.3% reporting bilateral symptoms. The length of continuous rest time had a significant impact on the incidence of finger triggering and disease stage ( P = .0275 and .0353, respectively; multivariate logistic regression). High-grade triggering had a more negative effect on rowing performance than low grade or no triggering (not significant). Conclusion: Ocean rowers suffered a 15-fold increase in trigger finger prevalence compared with the general population. This was increased in those who took shorter, more frequent rest periods. This study provides new conclusive evidence that the repetitive power grip and flexion involved in rowing increase the prevalence of trigger finger.

Scaphometacarpal arthroplasty: a report of ten cases of trapeziometacarpal prosthesis and trapeziectomy revision

Loosening of the trapezial component is a main cause of failure of trapeziometacarpal prostheses. This report presents the preliminary results of scaphometacarpal prostheses used for revision of trapeziometacarpal prostheses and failed trapeziectomies. A retrospective multicentre study was conducted on ten patients. Four had revision surgery after failure of trapeziometacarpal prostheses, five after trapeziectomy and one after a trapezial silicone implant. Pain, mobility, strength, QuickDASH, satisfaction score and radiographs were assessed. Nine patients were assessed (one was lost to follow-up), with a mean follow-up of 34 months. The mean pain score was 1.2/10, Quick-DASH was 39 and opposition according to the Kapandji score was 8.6. Strength was 3 kg for key pinch and 13.6 kg for power grip. One failure was observed, with early loosening of the scaphoid cup. Scaphometacarpal arthroplasty is a reliable medium-term solution for revision of the loosening of a trapeziometacarpal prosthesis with trapezial damage and for failed trapeziectomy. Level of evidence: IV