Effect of interelectrode distance on surface electromyographic signals of vastus intermedius muscle in women and men

Analysis of the Activation of Upper-Extremity Muscles During Various Chest Press Modalities

ABSTRACT

Christian, JR, Gothart, SE, Graham, HK, Barganier, KD, and Whitehead, PN. Analysis of the activation of upper-extremity muscles during various chest press modalities. J Strength Cond Res 37(2): 265-269, 2023-The most effective way to increase muscular strength is through the implementation of resistance training programs. The purpose of this study was to determine the level of muscle activation of the anterior deltoid (AD), medial deltoid (MD), and pectoralis major (PM) during various bench press scenarios. Twenty subjects (10 male and 10 female subjects; age, 24.0 ± 3.0 years) with a minimum of 1 year of resistance training were recruited to participate. Six surface electromyographical sensors were placed bilaterally on the targeted muscles. Subjects performed a 1 repetition maximum (1RM) of dumbbell (DB) and barbell (BB) flat bench press across 2 sessions followed by 6 repetitions at an incline, flat, and decline position at a submaximal 70% 1RM BB and DB. Mean peak values for muscle activation were analyzed for each variation. A repeated-measures 1-way analysis of variance was used to compare muscle activation patterns across conditions. Significance was set at p ≤ 0.05. Activation of AD was significantly higher during incline BB compared with decline BB and decline DB ( p ≤ 0.019). Activation of MD was significantly lower than that of AD across all modalities ( p ≤ 0.040). Activation of PM was significantly lower during incline DB compared with decline DB ( p = 0.011). Differences among AD and PM may have been the result of the stability stipulation variations between DB or BB and the large biacromial breadth requirement. Lack of differentiation of muscle fibers within the PM during sensor placement could have led to lesser muscle activation recordings during decline. As significance was evident for PM when comparing genders ( p ≤ 0.021), and no significance was found among AD or MD, it can be inferred that the larger amounts of adipose tissue in the female subjects caused irregularities in the PM data.

Uroflow stop test with electromyography: a novel index of urinary continence recovery after RARP

PURPOSE

Urinary incontinence (UI) is one of the most bothersome surgical side effects after robot-assisted radical prostatectomy (RARP). Alteration of both smooth and striate urethral sphincter occurs after RARP. Since the contraction of perineal muscles is involved in the complex mechanism of urinary continence, the uroflow stop test (UST) seems to predict early continence recovery after RARP. The UST was added of perineal surface electromyography (EMG) evaluation to evaluate the latency time (LT) between muscular contraction and the complete stop of urine flow. Our aim was to present UST-EMG as a new tool in the investigation of UI, implying pelvic floor integrity, and to evaluate whether an early return (≤ 3 months) to preoperative LT could be associated with early recovery of UC (≤ 3 months).

METHODS

After prospectively enrolling 137 patients who underwent RARP with a minimum follow-up of 6 months, we identified two groups: Group 1 (93 patients) with early (≤ 3 months) pre-surgical LT recovery and Group 2 (44 patients) with late > 3 months or not able to reach pre-surgical LT recovery.

RESULTS

Between the two groups, there were significant differences in terms of different surgical technique (nerve-sparing versus non-nerve-sparing) and pads use at 3 and 6 months after RARP (p < 0.05). No differences were recorded neither in postoperative maximum flow-rate, nor in postoperative symptoms score.

CONCLUSIONS

UST with EMG can be considered as a noninvasive, reproducible and easily performable tool. LT is applicable in the clinical evaluation to predict urinary continence recovery after RARP.

Structural diversity of the vastus intermedius origin revealed by analysis of isolated muscle specimens

The quadriceps femoris (QF), a major extensor of the knee joint, plays an important role in human movement. However, descriptions of the three vastus muscles of the QF in anatomy textbooks remain confusing. We analyzed 33 QFs by a novel approach, using isolated muscle specimens to clarify the structures of the vastus lateralis (VL), vastus medialis (VM), and vastus intermedius (VI) origins. The origins of the VL and VM were quite constant in shape and location, but the VI was much more structurally diverse. In typical cases (23 of 33), the origin of the VI attached muscularly to the anterior and lateral surface of the femoral shaft. It adjoined the origin of the VL at the lateral lip (LL) of the linea aspera to form a common origin. In some cases (10 of 33), the muscle belly and origin of the VI were much smaller than those in the typical cases; the origin of the VI attached only to the anterior surface of the femur and did not contact the LL. In addition, the muscle belly of the VI was narrow and almost corresponded to the width of the femoral shaft. The isolated muscle specimen is a useful tool for analyzing individual muscle structures, which can be difficult to observe by routine dissection. Using this method, it became clear that the VI is more structurally diverse in its origin than the VL and VM. Clin. Anat. 30:98-105, 2017. © 2016 Wiley Periodicals, Inc.