The effects of exercise type and elbow angle on vertical ground reaction force and muscle activity during a push-up plus exercise

Background

Proper alignment of the scapula during upper extremity motion is important in maintaining shoulder joint function and health. Push-up plus exercise is considered as one of the best exercise to strengthen the muscles that stabilize the scapula. The purpose of the study is to examine the effects of push-up plus variants and elbow position on vertical ground reaction force and electromyographical activity of four shoulder muscles during concentric contraction.

Methods

A total of 22 healthy subjects volunteered for the study. Each of the subjects performed both modified and traditional push-up plus. Modified push-up plus was performed with both knees and hands touching the ground while the traditional push-up plus was executed with hands and feet contacting the ground. Electromyography (EMG) of the upper trapezius (UT), lower trapezius (LT), infraspinatus (INFRA), and serratus anterior (SA), and vertical ground reaction forces (vGRF) were collected.

Results

The traditional push-up plus exhibited higher EMG activity in all muscles tested (P < .05) and vertical ground reaction force (P < .001) compared to modified push-up plus. The highest difference in EMG activity between the two exercises was observed with the Serratus Anterior muscle (22%). Additionally, the traditional push-up plus presented a higher vGRF compared to the modified push-up plus (P < .001) by 17%. The SA had the greatest EMG activity compared to the other muscles tested during the concentric phase of the traditional push-up plus, and this did not occur during the plus phase of the exercise.

Conclusion

The highest activity of the serratus anterior occurred at 55° of elbow extension during the concentric phase of the traditional PUP and not at the plus phase of the exercise. This suggests that when prescribing an exercise to target the serratus anterior, a traditional push-up is adequate and the plus-phase is not necessary. However, for patients that cannot perform a traditional push-up, the modified push-up plus would be a great alternative to strengthen their serratus anterior.     

Romosozumab Enhances Vertebral Bone Structure in Women With Low Bone Density

Romosozumab monoclonal antibody treatment works by binding sclerostin and causing rapid stimulation of bone formation while decreasing bone resorption. The location and local magnitude of vertebral bone accrual by romosozumab and how it compares to teriparatide remains to be investigated. Here we analyzed the data from a study collecting lumbar computed tomography (CT) spine scans at enrollment and 12 months post-treatment with romosozumab (210 mg sc monthly, n = 17), open-label daily teriparatide (20 μg sc, n = 19), or placebo (sc monthly, n = 20). For each of the 56 women, cortical thickness (Ct.Th), endocortical thickness (Ec.Th), cortical bone mineral density (Ct.bone mineral density (BMD)), cancellous BMD (Cn.BMD), and cortical mass surface density (CMSD) were measured across the first lumbar vertebral surface. In addition, color maps of the changes in the lumbar vertebrae structure were statistically analyzed and then visualized on the bone surface. At 12 months, romosozumab improved all parameters significantly over placebo and resulted in a mean vertebral Ct.Th increase of 10.3% versus 4.3% for teriparatide, an Ec.Th increase of 137.6% versus 47.5% for teriparatide, a Ct.BMD increase of 2.1% versus a −0.1% decrease for teriparatide, and a CMSD increase of 12.4% versus 3.8% for teriparatide. For all these measurements, the differences between romosozumab and teriparatide were statistically significant (p < 0.05). There was no significant difference between the romosozumab-associated Cn.BMD gains of 22.2% versus 18.1% for teriparatide, but both were significantly greater compared with the change in the placebo group (−4.6%, p < 0.05). Cortical maps showed the topographical locations of the increase in bone in fracture-prone areas of the vertebral shell, walls, and endplates. This study confirms widespread vertebral bone accrual with romosozumab or teriparatide treatment and provides new insights into how the rapid prevention of vertebral fractures is achieved in women with osteoporosis using these anabolic agents. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).     

Operation Enduring Freedom: trends in combat casualty care by forward surgical teams deployed to Afghanistan

This study examined the clinical experience of a U.S. Army Forward Surgical Team (FST) deployed to Afghanistan in 2005 and compared the findings with those of 3 previously deployed FSTs. Medical records of all patients evaluated by the FST were abstracted for analysis. Demographically, the cohort (n = 614) was predominantly male (94%), with a median age of 24, and distributed according to the following: disease (8.6%), nonbattle injury (42%), and battle injury (49%). Combat casualties were mostly Afghan National Army or Police (56%) and U.S. military (21%). Predominant wounding instruments were small arms (34%), improvised explosive devices (33%), and rocket-propelled grenades (15%). Anatomical sites of battle injury were extremities (38%), external soft tissue (35%), and head/neck/torso (28%). Operative procedures for combat injury (n = 227) were primarily orthopedic (45%) or thoracic/abdominal (36%). Combat casualty statistics provide insight to trauma epidemiology, patterns, and trends vital for surgical management. Workload statistics guides the structuring, training, and employment of FSTs.     

Differentiation of fetal pig endocrine cells after allografting into the thymus gland

BACKGROUND: The thymus of large animals, such as the pig, is thought to be an appropriate site for transplanting adult islets, which contain numerous beta cells, for the purpose of reversing diabetes. Whether fetal islet-like cell clusters (ICCs), which contain few beta cells, will develop at this site, so that adequate amounts of insulin can be produced, is unknown. METHODS: Between 15,000 and 40,000 ICCs were injected into the thymus gland of six juvenile immunosuppressed pigs, and the animals were killed up to 30 days later. The graft was then examined histologically and comparisons made with untransplanted ICCs and those grafted into the omentum of immunosuppressed pigs. RESULTS: At transplantation, the percentage of cells in the ICCs containing insulin, glucagon, somatostatin, or pancreatic polypeptide was 9+/-1%, 13+/-2%, 9+/-1%, and 3+/-1% respectively. Within 9-30 days of transplantation into the thymus, the percentage of all endocrine cells increased, insulin to 41+/-3%, glucagon to 43+/-6%, somatostatin to 26+/-4%, and pancreatic polypeptide to 9+/-3%. There was co-localization of more than one hormone in some cells. Omental grafts contained a similar percentage of insulin and glucagon-containing cells, but significantly fewer somatostatin and pancreatic polypeptide-containing cells. CONCLUSIONS: Endocrine cells from the fetal pig pancreas will differentiate when transplanted into the thymus gland of the pig, making this a suitable site for grafting ICCs to test their ability to normalize blood glucose levels of diabetic recipients.     

Effects of ovarian hormones and aging on respiratory sinus arrhythmia and breathing patterns in women

We investigated the effect of ovarian hormones and aging on breathing pattern [pulmonary minute ventilation (V(E))], tidal volume (V(T)), breathing frequency (F(b)), and respiratory sinus arrhythmia (RSA) in women. Recordings of V(E) and electrocardiogram (ECG) were obtained from 23 healthy women (10 premenopausal, 13 postmenopausal) under resting, isocapnic hypoxia (IH), and euoxic hypercapnia (EH) conditions. Premenopausal women were tested on three different days, each day corresponding to a specific phase of the menstrual cycle (follicular, mid-cycle, and luteal); postmenopausal women (PMW) were tested on 1 day only. On each test day, subjects were challenged with IH and EH. The order of the two tests was randomized and separated by at least 1 hour. Due to the low F (b) of several PMW, the band limits for RSA analysis had to be adjusted. The spectral coherence between respiratory flow and ECG RR-interval was used to determine the spectral band. Within the spectral band, there was a consistent phase relationship between the two variables where high values of spectral coherence indicate a well-defined phase relationship between respiratory flow and RR-interval variability. The main findings in this study for RSA are fourfold. First, RSA did not change with different levels of ovarian hormones (progesterone, serum 17beta-estradiol) during the menstrual cycle. Second, RSA was not influenced by hormone replacement therapy. Third, RSA did not change with age. Fourth, RSA did not change with IH and EH-induced changes in breathing patterns. Finally, high individual variability of average RR-interval change per breath was found.     

Effects of clonidine, prazosin and phentolamine on heart rate and coronary sinus catecholamine concentration during cardioaccelerator nerve stimulation in spinal dogs

1 In spinal dogs, continuous electrical stimulation of the cardioaccelerator nerve produced a transient rise in aortic blood pressure and a sustained increase in both heart rate and coronary sinus blood flow. The latter effects were accompanied by a significant elevation in the coronary sinus plasma noradrenaline concentration without significant changes in the levels of dopamine and adrenaline. The concentrations of the three catecholamines in thoracic aorta plasma were not significantly changed by cardioaccelerator nerve stimulation.

2 Clonidine (20 μg/kg, i.v.), given during cardioaccelerator nerve stimulation, increased both mean aortic blood pressure and coronary sinus blood flow and decreased heart rate and coronary sinus venous plasma noradrenaline overflow.

3 Phentolamine (0.3 mg/kg, i.v.) completely antagonized these effects of clonidine. Prazosin (0.3 mg/kg, i.v.) inhibited by only 43 and 38% the respective reductions in heart rate and noradrenaline overflow elicited by clonidine.

4 On termination of cardioaccelerator stimulation (about 10 min after either prazosin or phentolamine), heart rate and coronary sinus noradrenaline overflow returned to control prestimulation levels.

5 Phentolamine or prazosin, administered alone during stimulation of the cardioaccelerator nerve, increased heart rate and noradrenaline overflow into the coronary sinus plasma. However, intravenous phentolamine and prazosin, in contrast to desipramine (0.3 mg/kg, i.v.) or tyramine (1.0 mg, i.a.), failed to change the tachycardia resulting from the local administration of noradrenaline into the sinus node artery (i.a.).

6 These results show that in spinal dogs the clonidine-induced reduction in heart rate (elevated by electrical stimulation of the cardioaccelerator nerve) is accompanied by a fall in the quantity of noradrenaline overflowing into the coronary sinus plasma. The latter effect is presumably the result of an action of clonidine on cardiac presynaptic α-adrenoceptors, the activation of which is followed by a reduction in the release of noradrenaline per nerve impulse. Phentolamine and prazosin are both antagonists of cardiac presynaptic α-adrenoceptors in spinal dogs, as suggested by their action against clonidine and by their positive chronotropic effect when administered during stimulation of the cardioaccelerator nerve.

     

Myocardial perfusion imaging with technetium-99m sestamibi SPECT in the evaluation of coronary artery disease

Technetium-99m hexakis-2-methoxy-isobutyl-isonitrile(^99mTc sestamibi) has been used for myocardial perfusion imaging in the evaluation of coronary artery disease (CAD) since 1990. The experience of its use in an Asian population with and without previous myocardial infarction (Ml), diabetes mellitus (DM), hypertension (HPT) and collateral circulation (COL) is reported. One hundred and thirty-nine patients who underwent treadmill exercise testing with ^99mTc sestamibi single photon emission computed tomography (SPECT) and coronary angiogram were studied. The overall sensitivity for the detection of CAD was 91.0% and specificity was 64.7%. For patients without previous myocardial infarction, the sensitivity was 83.8% and specificity was 83.3%. Patients with COL had a higher sensitivity while those with HPT had a lower specificity. Sensitivity was higher in patients with multi-vessel disease (MVD) than single vessel disease (SVD). The overall detection for individual artery stenosis was 74.1% with a specificity of 73.1 %. Amongst the three major coronary arteries, sensitivity was highest for the right coronary artery and specificity was highest for the left circumflex artery. Specificity was higher in patients without MI or COL. We found that the agreement between ^99mTc sestamibi SPECT and coronary angiogram for the extent of CAD was only 52.5%. The concordance rate was higher for patients with MVD than SVD. It is concluded that ^99mTc sestamibi SPECT is a sensitive and specific test for the detection of CAD and localization of disease to individual coronary arteries in our patients with some differences in the subgroups. Agreement between coronary angiogram and ^99mTc sestamibi for the extent of coronary artery disease was also satisfactory.