scholarly journals Effects of training, detraining, and retraining on strength, hypertrophy, and myonuclear number in human skeletal muscle

2019 ◽  
Vol 126 (6) ◽  
pp. 1636-1645 ◽  
Author(s):  
Niklas Psilander ◽  
Einar Eftestøl ◽  
Kristoffer Toldnes Cumming ◽  
Inga Juvkam ◽  
Maria M. Ekblom ◽  
...  
Keyword(s):  
Strength Training ◽  
Animal Experiments ◽  
Muscle Thickness ◽  
Fiber Volume ◽  
Cross Sectional ◽  
Leg Extension ◽  
Training Response ◽  
Before And After ◽  
Muscle Memory ◽  
Unilateral Strength Training

Previously trained mouse muscles acquire strength and volume faster than naïve muscles; it has been suggested that this is related to increased myonuclear density. The present study aimed to determine whether a previously strength-trained leg (mem-leg) would respond better to a period of strength training than a previously untrained leg (con-leg). Nine men and 10 women performed unilateral strength training (T1) for 10 wk, followed by 20 wk of detraining (DT) and a 5-wk bilateral retraining period (T2). Muscle biopsies were taken before and after each training period and analyzed for myonuclear number, fiber volume, and cross-sectional area (CSA). Ultrasound and one repetition of maximum leg extension were performed to determine muscle thickness (MT) and strength. CSA (~17%), MT (~10%), and strength (~20%) increased during T1 in the mem-leg. However, the myonuclear number and fiber volume did not change. MT and CSA returned to baseline values during DT, but strength remained elevated (~60%), supporting previous findings of a long-lasting motor learning effect. MT and strength increased similarly in the mem-leg and con-leg during T2, whereas CSA, fiber volume, and myonuclear number remained unaffected. In conclusion, training response during T2 did not differ between the mem-leg and con-leg. However, this does not discount the existence of human muscle memory, since no increase in the number of myonuclei was detected during T1 and no clear detraining effect was observed for cell size during DT; thus, the present data did not allow for a rigorous test of the muscle memory hypothesis. NEW & NOTEWORTHY If a long-lasting intramuscular memory exists in humans, this will affect strength-training advice for both athletes and the public. Based on animal experiments, we hypothesized that such a memory exists and that it is related to the myonuclear number. However, a period of unilateral strength training, followed by detraining, did not increase the myonuclear number. The training response, during a subsequent bilateral retraining period, was not enhanced in the previously trained leg.

scholarly journals Unilateral strength training leads to muscle-specific sparing effects during opposite homologous limb immobilization

2018 ◽  
Vol 124 (4) ◽  
pp. 866-876 ◽  
Author(s):  
Justin W. Andrushko ◽  
Joel L. Lanovaz ◽  
Kelsey M. Björkman ◽  
Saija A. Kontulainen ◽  
Jonathan P. Farthing
Keyword(s):  
Strength Training ◽  
Muscle Thickness ◽  
Training Group ◽  
Sectional Area ◽  
Cross Sectional ◽  
Multiple Contraction ◽  
Contraction Type ◽  
Muscle Cross Sectional Area ◽  
Wrist Flexors ◽  
Unilateral Strength Training

Cross education (CE) occurs after unilateral training whereby performance of the untrained contralateral limb is enhanced. A few studies have shown that CE can preserve or “spare” strength and size of an opposite immobilized limb, but the specificity (i.e., trained homologous muscle and contraction type) of these effects is unknown. The purpose was to investigate specificity of CE “sparing” effects with immobilization. The nondominant forearm of 16 participants was immobilized with a cast, and participants were randomly assigned to a resistance training (eccentric wrist flexion, 3 times/week) or control group for 4 weeks. Pre- and posttesting involved wrist flexors and extensors eccentric, concentric and isometric maximal voluntary contractions (via dynamometer), muscle thickness (via ultrasound), and forearm muscle cross-sectional area (MCSA; via peripheral quantitative computed tomography). Only the training group showed strength preservation across all contractions in the wrist flexors of the immobilized limb (training: −2.4% vs. control: −21.6%; P = 0.04), and increased wrist flexors strength of the nonimmobilized limb (training: 30.8% vs. control: −7.4%; P = 0.04). Immobilized arm MCSA was preserved for the training group only (training: 1.3% vs. control: −2.3%; P = 0.01). Muscle thickness differed between groups for the immobilized (training: 2.8% vs. control: −3.2%; P = 0.01) and nonimmobilized wrist flexors (training: 7.1% vs. control: −3.7%; P = 0.02). Strength preservation was nonspecific to contraction type ( P = 0.69, [Formula: see text] = 0.03) yet specific to the trained flexors muscle. These findings suggest that eccentric training of the nonimmobilized limb can preserve size of the immobilized contralateral homologous muscle and strength across multiple contraction types.NEW & NOTEWORTHY Unilateral strength training preserves strength, muscle thickness, and muscle cross-sectional area in an opposite immobilized limb. The preservation of size and strength was confined to the trained homologous muscle group. However, strength was preserved across multiple contraction types.

Strength training the free limb attenuates strength loss during unilateral immobilization

2009 ◽  
Vol 106 (3) ◽  
pp. 830-836 ◽  
Author(s):  
Jonathan P. Farthing ◽  
Joel R. Krentz ◽  
Charlene R. A. Magnus
Keyword(s):  
Strength Training ◽  
Muscle Activation ◽  
Muscle Thickness ◽  
Strength Loss ◽  
Peak Torque ◽  
Ulnar Deviation ◽  
Before And After ◽  
Cross Education ◽  
The Right ◽  
Arm Strength

The objective was to determine if strength training the free limb during a 3-wk period of unilateral immobilization attenuates strength loss in the immobilized limb through cross-education. Thirty right-handed participants were assigned to three groups. One group ( n = 10) wore a cast and trained the free arm (Cast-Train). A second group ( n = 10) wore a cast and did not train (Cast). A third group ( n = 10) received no treatment (control). Casts were applied to the nondominant (left) wrist and hand by a physician. Strength training was maximal isometric ulnar deviation (right hand) 5 days/wk. Peak torque (dynamometer), electromyography (EMG), and muscle thickness (ultrasound) were assessed in both arms before and after the intervention. Cast-Train improved right arm strength [14.3 (SD 5.0) to 17.7 (SD 4.8) N·m; P < 0.05] with no significant muscle hypertrophy [3.73 (SD 0.43) to 3.84 (SD 0.52) cm; P = 0.09]. The immobilized arm of Cast-Train did not change in strength [13.9 (SD 4.3) to 14.2 (SD 4.6) N·m] or muscle thickness [3.61 (SD 0.51) to 3.57 (SD 0.43) cm]. The immobilized arm of Cast decreased in strength [12.2 (SD 3.8) to 10.4 (SD 2.5) N·m; P < 0.05] and muscle thickness [3.47 (SD 0.59) to 3.32 (SD 0.55) cm; P < 0.05]. Control showed no changes in the right arm [strength: 15.3 (SD 6.1) to 14.3 (SD 5.8) N·m; muscle thickness: 3.57 (SD 0.68) to 3.52 (SD 0.75) cm] or left arm [strength: 14.5 (SD 5.3) to 13.7 (SD 6.1) N·m; muscle thickness: 3.55 (SD 0.77) to 3.51 (SD 0.70) cm]. Agonist muscle activation remained unchanged after the intervention for both arms [right: 302 (SD 188) to 314 (SD 176) μV; left: 261 (SD 139) to 288 (SD 151) μV] with no group differences. Strength training of the free limb attenuated strength loss in the immobilized limb during unilateral immobilization. Strength training may have prevented muscle atrophy in the immobilized limb.

scholarly journals Comparative Study of the Effects of 1% Atropine on the Anterior Segment

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yue Zhou ◽  
Xiao Bo Huang ◽  
Qi Cai ◽  
Jun Jie Li ◽  
Yao Jia Xiong ◽  
...  
Keyword(s):  
Anterior Chamber ◽  
Univariate Analysis ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Muscle Thickness ◽  
Ultrasound Biomicroscopy ◽  
Cross Sectional ◽  
Ciliary Process ◽  
Before And After ◽  
Anterior Segment Parameters

Purpose. To investigate the influences of atropine on changes in anterior segment geometry, as measured by ultrasound biomicroscopy in children. Methods. A prospective observational study was performed. Anterior segment parameters were obtained by UBM before and after the instillation of 1% atropine. Univariate linear regression was performed to identify the variables contributing to the changes in the trabecular meshwork-iris angle (TIA). Results. The study included 21 boys and 37 girls with a mean age of 10.79 ± 2.53 years. Anterior chamber parameters including the central anterior chamber depth, TIA, angle opening distance at 500 μm from the scleral spur, iris thickness 750 μm and 1500 μm from the scleral spur, trabecular-ciliary angle (TCA), trabecular-ciliary process distance, sclera-iris angle (SIA), and sclera-ciliary process angle significantly increased after cycloplegia ( P < 0.05 ). In contrast, the lens vault, iris cross-sectional area, and maximum ciliary muscle thickness significantly decreased after cycloplegia. Univariate analysis identified the change in TCA and the change in SIA and the TIA before mydriasis as determinants of the change in TIA. Conclusions. Atropine causes statistically significant changes in various anterior segment parameters in children. The change in anterior chamber angle is associated with the change in TCA and the change in SIA and the TIA before mydriasis.

scholarly journals Correlates of and changes in aerobic physical activity and strength training before and after the onset of COVID-19 pandemic in the UK. Findings from the HEBECO study.

2021 ◽  
Author(s):  
Aleksandra Herbec ◽  
Verena Schneider ◽  
Abi Fisher ◽  
Dimitra Kale ◽  
Lion Shahab ◽  
...  
Keyword(s):  
Physical Activity ◽  
Strength Training ◽  
Older Age ◽  
Annual Household Income ◽  
Cross Sectional ◽  
Education Access ◽  
White Ethnicity ◽  
Before And After ◽  
The Uk ◽  
Sectional Analysis

Objectives: Understanding changes in moderate to vigorous aerobic physical activity (MVPA) and strength training (MSA) from before to after (pre-/post-) the onset of the Covid-19 pandemic in the UK (first lockdown) and their correlates can inform interventions. Methods: Cross-sectional analysis of retrospective and concurrent data on MVPA/MSA pre- and post-Covid-19 (until 14th June 2020) among 2,657 UK adults. The associations between socio-demographic and health characteristics, MVPA/MSA pre-Covid-19, living and exercise conditions and meeting WHO recommended levels for MVPA/MSA/both (vs meeting neither), and changes in MVPA/MSA from pre- to post-Covid-19 following stratification for pre-Covid-19 MVPA/MSA levels were evaluated. Results: A third of adults maintained (30.4%), decreased (36.2%) or increased (33.4%) their MVPA levels post-Covid-19. For MSA, the percentages were 61.6%, 18.2%, and 20.2%, respectively. MVPA increased or decreased by an average of 150min/week, and MSA by 2 days/week. Meeting both MSA+MVPA recommendations during lockdown (vs. meeting neither) was positively associated with meeting MVPA+MSA pre-lockdown (aOR=16.11,95%CI=11.24-23.07), and post-16-years of age education (aOR=1.57,1.14-2.17), and negatively associated with being obese (aOR=0.49,0.33-0.73), older age (65+ vs ≤34; aOR=.53,.32-.87), and annual household income <50.000GBP (vs ≥50.000GBP; aOR=0.65,0.46-0.91). The odds for decreasing MVPA were significantly lower for white ethnicity, post-16-years of age education, access to garden/balcony, and higher for those who were in total isolation. The odds for decreasing MSA were significantly higher for those who were overweight or obese. Conclusion: Aerobic and strength training were differently impacted during the first UK lockdown, with poorer outcomes associated with older age, lower education, and higher body mass index.

Electrical Stimulation to the Infraspinatus on Hypertrophy and Strength of the Shoulder

2018 ◽  
Vol 39 (11) ◽  
pp. 828-834 ◽  
Author(s):  
Ko Yanase ◽  
Satoshi Hasegawa ◽  
Masatoshi Nakamura ◽  
Taishi Yamauchi ◽  
Satoru Nishishita ◽  
...  
Keyword(s):  
Muscle Thickness ◽  
Control Group ◽  
Muscle Stimulation ◽  
Sectional Area ◽  
Electrical Muscle Stimulation ◽  
Cross Sectional ◽  
Infraspinatus Muscle ◽  
Before And After ◽  
Stimulation Group ◽  
Electrical Muscle

AbstractThe purpose of this study was to determine the effects of six weeks of electrical muscle stimulation (EMS) on the strength and muscle mass of the infraspinatus muscle. Twenty non-athletes (age: 24±3.4 years, height: 171.5±5.6 cm, mass: 65.2±8.1 kg) were randomly classified into two groups, an electrical muscle stimulation group (EMS group) and a control group (CON group). The EMS group completed a total of 18 20– min EMS sessions, three times per week over a period of six weeks, while the CON group received no intervention. The muscle thicknesses of both the infraspinatus and the deltoid muscles, the cross-sectional area (CSA) of the whole infraspinatus muscle, and the isometric and isokinetic peak torques of shoulder external rotations were measured before and after intervention. It was found that the muscle thickness of the superior infraspinatus (Pre 0.92±0.19 cm2, Post 0.99±0.16 cm2, p=0.02) and the CSA (Pre 10.99±1.32 cm2, Post 11.99±1.02 cm2, p=0.03) significantly increased in the EMS group. This study demonstrated that EMS of the infraspinatus muscle over a period of six weeks resulted in hypertrophy of the infraspinatus muscle.

Muscle quality. II. Effects of strength training in 65- to 75-yr-old men and women

1999 ◽  
Vol 86 (1) ◽  
pp. 195-201 ◽  
Author(s):  
B. L. Tracy ◽  
F. M. Ivey ◽  
D. Hurlbut ◽  
G. F. Martel ◽  
J. T. Lemmer ◽  
...  
Keyword(s):  
Strength Training ◽  
Older Women ◽  
Knee Extensor ◽  
Older Men ◽  
Quadriceps Muscle ◽  
Muscle Volume ◽  
Muscle Quality ◽  
Men And Women ◽  
Leg Extension ◽  
Before And After

To determine the effects of strength training (ST) on muscle quality (MQ, strength/muscle volume of the trained muscle group), 12 healthy older men (69 ± 3 yr, range 65–75 yr) and 11 healthy older women (68 ± 3 yr, range 65–73 yr) were studied before and after a unilateral leg ST program. After a warm-up set, four sets of heavy-resistance knee extensor ST exercise were performed 3 days/wk for 9 wk on the Keiser K-300 leg extension machine. The men exhibited greater absolute increases in the knee extension one-repetition maximum (1-RM) strength test (75 ± 2 and 94 ± 3 kg before and after training, respectively) and in quadriceps muscle volume measured by magnetic resonance imaging (1,753 ± 44 and 1,955 ± 43 cm3) than the women (42 ± 2 and 55 ± 3 kg for the 1-RM test and 1,125 ± 53 vs. 1,261 ± 65 cm3 for quadriceps muscle volume before and after training, respectively, in women; both P < 0.05). However, percent increases were similar for men and women in the 1-RM test (27 and 29% for men and women, respectively), muscle volume (12% for both), and MQ (14 and 16% for men and women, respectively). Significant increases in MQ were observed in both groups in the trained leg (both P < 0.05) and in the 1-RM test for the untrained leg (both P < 0.05), but no significant differences were observed between groups, suggesting neuromuscular adaptations in both gender groups. Thus, although older men appear to have a greater capacity for absolute strength and muscle mass gains than older women in response to ST, the relative contribution of neuromuscular and hypertrophic factors to the increase in strength appears to be similar between genders.

SUBLINGUAL VITAMIN D3 DRUG THERAPY IN VITAMIN D DEFICIENCY PATIENTS AT PRAVARA RURAL HOSPITAL

2019 ◽  
pp. 18-20
Author(s):  
Sanjeeva Kumar Goud T ◽  
Rahul Kunkulol
Keyword(s):  
Vitamin D ◽  
Vitamin D Deficiency ◽  
Vitamin D3 ◽  
Serum Vitamin ◽  
Cross Sectional ◽  
Serum Vitamin D ◽  
Significant Difference ◽  
Before And After

The present study was aimed to study the effect of Sublingual Vitamin D3 on Serum Vitamin D level in Vitamin D deficiency patients. This was a cross-sectional and interventional study. All the Vitamin D deficiency patients of age 18-60years and either gender, willing to participate in the study were included. Patients who had greater than 20 ng/ml were excluded from the study. The total number of participants in our study was 200, out of these 111 males and 89 females, the mean age in our study was 51.07 ± 7.39Yrs. All volunteers were given sublingual vitamin D3 (60,000IU) in six doses every fifteen days of follow up for 3 months. The subject’s serum 25(OH)D levels were estimated before and after the treatment of sublingual vitamin D3. There was a statistically significant difference in serum vitamin D3 level before 16.61±6.71 ng/ml and after 35.80±7.80 ng/ml after treatment with Sublingual Vitamin D3. Six doses of 60,000IU of Vitamin D3 sublingual route having improved the role of serum 25(OH)D levels in the treatment of Vitamin D3 deficiency patients.Keywords: Vitamin D3; Sublingual route

The Degree of Subjective Complaints of Students Practice in Mechanical Technology Laboratories

2018 ◽  
Vol 4 (1) ◽  
pp. 22
Author(s):  
I Ketut Widana
Keyword(s):  
Engineering Students ◽  
Standing Position ◽  
Statistical Test ◽  
Rank Test ◽  
Cross Sectional ◽  
Signed Rank ◽  
Before And After ◽  
Signed Rank Test ◽  
The Difference ◽  
Paired T Test

The working practice of the engineering students is part of the learning process that is irreducible and indispensable. The composition of  lecturing between theoretical and practical one is 40% to 60%. With this condition, the students spend more time at the laboratory. Generally, the students perform in the laboratory work by standing position. The design of research is observational cross-sectional. The method applied is observation, interview and measuring. The subjects of research are practicing students amounting to 21 students. Referring to the analysis of statistical test or Wilcoxon signed ranks test, the difference of effect of work position is significant, namely p < 0.05 towards musculoskeletal disorders (MSDs) before and after working. The quantity of the average complaint after working is score 44.62 ± 9.47. The result of Wilcoxon signed rank test shows that there is significant different effects of standing work position, namely p < 0.05 towards fatigue generally before and after working. The degree of the working pulse is on the average of 110.78  ± 17.80 bpm (beats per minutes) which can be categorized into the medium workload. Using paired t-test, the result is p < 0.05.

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