scholarly journals Adaptations in the passive mechanical properties of skeletal muscle to altered patterns of use

2019 ◽  
Vol 126 (5) ◽  
pp. 1483-1491 ◽  
Author(s):  
Anthony J. Blazevich
Keyword(s):  
Physical Activity ◽  
Mechanical Properties ◽  
Range Of Motion ◽  
Research Effort ◽  
Muscle Stiffness ◽  
Plantar Flexors ◽  
Healthy Human ◽  
Exercise Interventions ◽  
Muscle Stretching ◽  
Muscle Groups

The aim of this mini-review is to describe the present state of knowledge regarding the effects of chronic changes in the patterns of muscle use (defined as changes lasting >1 wk), including muscle stretching, strengthening, and others, on the passive mechanical properties of healthy human skeletal muscles. Various forms of muscle stretch training and some forms of strength training (especially eccentric training) are known to strongly impact the maximum elongation capacity of muscles in vivo (i.e., maximum joint range of motion), largely by increasing our ability to tolerate higher stretch loads. However, only small effects are observed in the passive stiffness of the muscle-tendon unit (MTU) or the muscle itself, although a reduction in muscle stiffness has been observed in the plantar flexors after both stretching and eccentric exercise interventions. No changes have yet been observed in viscoelastic properties such as the MTU stress-relaxation response, although a minimum of evidence indicates that hysteresis during passive stretch-relaxation cycles may be reduced by muscle stretching training. Importantly, data exist for relatively few muscle groups, and little is known about the effects of age and sex on the adaptive process of passive mechanical properties. Despite the significant research effort afforded to understanding the effects of altered physical activity patterns on the maximum range of motion at some joints, further information is needed before it will be possible to develop targeted physical activity interventions with the aim of evoking specific changes in passive mechanical properties in individuals or in specific muscles and muscle groups.

scholarly journals Effects of Intermittent and Continuous Static Stretching on Range of Motion and Musculotendinous Viscoelastic Properties Based on a Duration-Matched Protocol

2021 ◽  
Vol 18 (20) ◽  
pp. 10632
Author(s):  
Kensuke Oba ◽  
Mina Samukawa ◽  
Yosuke Abe ◽  
Yukino Suzuki ◽  
Miho Komatsuzaki ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Range Of Motion ◽  
Repeated Measures ◽  
Plantar Flexors ◽  
Constant Torque ◽  
Resistive Torque ◽  
Repeated Measures Analysis ◽  
Before And After ◽  
Musculotendinous Stiffness ◽  
Torque Angle

The different effects of intermittent and continuous stretching on the mechanical properties of the musculotendinous complex have been unclear. This study aimed to compare the effects of intermittent and continuous stretching for the same duration on the range of motion (ROM), passive resistive torque (PRT), and musculotendinous stiffness (MTS) of ankle plantar flexors. Eighteen healthy young men participated in the study. Intermittent (four sets × 30 s) and continuous stretching (one set × 120 s) were performed in random orders on two separate days. Both stretching protocols were conducted using a dynamometer with a constant torque applied. ROM and PRT were determined using a dynamometer, and MTS was calculated using the torque–angle relationship measured before and after stretching. Two-way repeated measures analysis of variance was performed for all parameters. Both intermittent and continuous stretching significantly increased ROM and decreased PRT and MTS (p < 0.05). Intermittent stretching led to greater changes in ROM and PRT than continuous stretching. However, the reduction in MTS did not differ between the two conditions. These results suggest that intermittent stretching is more effective in increasing ROM and changing the mechanical properties of the musculotendinous complex.

Physical Activity in Aging Population

2019 ◽  
Vol 5 (3) ◽  
pp. 74
Author(s):  
Rezarta Stena ◽  
Klara Hysenaj ◽  
Mitilda Gugu Karoli ◽  
Armelda Teta ◽  
Gjergji Doka
Keyword(s):  
Physical Activity ◽  
Older Adults ◽  
Heart Rate ◽  
Pain Intensity ◽  
Range Of Motion ◽  
Training Program ◽  
Grip Strength ◽  
Upper Limb ◽  
Hand Grip ◽  
Trunk Flexibility

It is known that worldwide populations are aging, and also that physical activity can play an important role in minimizing impairments characteristic of old age. Adopting a more active lifestyle and doing regular physical activity, including aerobic and resistance exercises, daily walking etc. have been demonstrated to improve cardiovascular, respiratory, and musculoskeletal parameters in older adults. We assessed a potential participant from Elbasan (Albania), 67 years, for eligibility to participate in a 5 month training program. The subject gave written informed consent before inclusion.The following parameters were measured at the beginning (baseline) and end of the training period: BMI, body fat percentage, hand grip strength, lower/upper limb and trunk flexibility and range of motion, heart rate, balance, pain intensity, as well as VO2 max, directly and/or an estimate using the Rockport fitness test estimate. An initial evaluation was carried out just before starting the training (baseline). A second evaluation was made 5 months after starting the program of physical exercise (post training). Each evaluation included the recording of health related events, such as any changes in previous symptoms, as well as measurements of balance, flexibility, body composition, coordination, muscle strength, and aerobic capacity, to detect any changes that might have been induced specifically by physical activity. The subject’s attendance and participation in the program was also recorded. Range of motion for each part evaluated (trunk, hip, cervical region and shoulder) is improved about 15-20° degree. BMI, hand grip strength, lower/upper limb and trunk flexibility, heart rate, balance, pain intensity, VO2 max are also improved after training program. Following a training program or a regular physical activity in older adults minimise impairments characteristics in this age and cardiovascular, respiratory, and musculoskeletal parameters. According to the low importance shown in my country for the physical activity in older adults, I want to emphasize the importance of state structures involvement and the sensibilization of this group of age to stimulate an actively participation in physical training programs followed by professionals for bests life parameters. A higher investment for this age group, building as many facilities as possible for activation and spending quality free time, hiring more physiotherapists in nursing homes will increase life motivation and improve the quality and the parameters of living.

scholarly journals Body composition outcomes of Healthy Fit and the role of acculturation among low-income Hispanics on the US-Mexico border

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Diane I. Lopez ◽  
Lauren Chacon ◽  
Denise Vasquez ◽  
Louis D. Brown
Keyword(s):  
Physical Activity ◽  
Body Composition ◽  
Nutrition Education ◽  
Low Income ◽  
Vegetable Consumption ◽  
Overweight And Obesity ◽  
Foreign Born ◽  
Exercise Interventions ◽  
Mexico Border

Abstract Background Hispanic immigrants continue to experience higher rates of overweight and obesity compared to their non-Hispanic counterparts. Acculturation may contribute to unhealthy weight gain among immigrant populations by shifting dietary patterns from high fruit and vegetable consumption to unhealthier high fat diets. Healthy Fit, a culturally tailored community health worker (CHW) intervention, aims to reduce obesity related outcomes by providing physical activity and nutrition education and resources in a low-income Hispanic population. This study aims to evaluate outcomes of Healthy Fit participants and examine changes in body composition in relation to level of acculturation at baseline and follow-up. Method In this longitudinal observational study, CHWs recruited 514 participants from community events and agencies serving low-income Hispanic populations in El Paso, Texas from 2015 to 2016. Following an in-person health screening, eligible participants received nutrition and physical activity education guided by fotonovelas, comic-like educational books. Telephone follow-ups made at 1, 3, and 6 months by CHWs encouraged follow-through on referrals. 288 participants completed the screening again during the 12-month follow-up. Results The sample was predominantly Hispanic (96%), female (82%), uninsured (79%), had a household income of less than $19,999 (70%), foreign-born (79%), preferred Spanish (86%) and few rated themselves as good or excellent for English proficiency (27%). Overall, Healthy Fit participants significantly improved (i.e., decreased) BFP by 0.71% (t = 2.47, p = 0.01) but not BMI (b = .01, t = − 0.14, p = .89). Contrary to expectations, acculturation was not associated with lower BMI (b = 0.09, p = 0.84) or BFP (b = 0.13, p = 0.85) at baseline. However, acculturation predicted changes in both BMI (b = 0.30, p = 0.03) and BFP (b = 1.33, p = 0 .01) from baseline to follow-up. Specifically, the low acculturation group improved in body composition measures over time and the high acculturation group did not improve in either measure. Conclusion Findings suggest Healthy Fit was most effective among less acculturated individuals. The influence of acculturation on the efficacy of nutrition and exercise interventions suggests that Hispanics should not be treated as a homogenous subgroup.

Effects of Exercise Interventions on Habitual Physical Activity and Sedentary Behavior in Adolescents With Cerebral Palsy

2019 ◽  
Vol 31 (4) ◽  
pp. 416-424 ◽  
Author(s):  
Simona Bar-Haim ◽  
Ronit Aviram ◽  
Anat Shkedy Rabani ◽  
Akram Amro ◽  
Ibtisam Nammourah ◽  
...  
Keyword(s):  
Physical Activity ◽  
Cerebral Palsy ◽  
Resistance Training ◽  
Sedentary Behavior ◽  
Motor Function ◽  
Classification System ◽  
Habitual Physical Activity ◽  
Progressive Resistance Training ◽  
Exercise Interventions ◽  
Progressive Resistance

Purpose:Exercise interventions have been shown to increase motor capacities in adolescents with cerebral palsy; however, how they affect habitual physical activity (HPA) and sedentary behavior is unclear. The main objective was to correlate changes in HPA with changes in mobility capacity following exercise interventions.Methods:A total of 54 participants (aged 12–20 y) with bilateral spastic cerebral palsy at Gross Motor Function Classification System (GMFCS) levels II and III received 4 months of group progressive resistance training or treadmill training. Mobility measurements and HPA (averaged over 96 h) were made before and after interventions.Results:Averaged baseline mobility and HPA measures and improvements in each after both interventions were positively correlated in all participants. Percentage of sedentary/awake time decreased 2%, with significant increases in HPA measures of step count (16%), walk time (14%), and upright time (9%). Mobility measures and HPA changes were quite similar between Gross Motor Function Classification System levels, but improvement in HPA after group progressive resistance training was greater than after treadmill training (12% vs 4%) and correlated with mobility improvement.Conclusions:Mobility capacity improved after these interventions and was clearly associated with improved HPA. The group progressive resistance training intervention seems preferable to improve HPA, perhaps related to greater social interaction and motivation provided by group training.

Investigations on the Mechanical Properties and Formability of Friction Stir Welded Tailored Blanks

2007 ◽  
Vol 344 ◽  
pp. 143-150 ◽  
Author(s):  
Gianluca Buffa ◽  
Livan Fratini ◽  
Marion Merklein ◽  
Detlev Staud
Keyword(s):  
Mechanical Properties ◽  
Stress Condition ◽  
Research Effort ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Friction Stir ◽  
Tailored Blanks ◽  
Sheet Stamping ◽  
Wide Range

Tight competition characterizing automotive industries in the last decades has determined a strong research effort aimed to improve utilized processes and materials in sheet stamping. As far as the latter are regarded light weight alloys, high strength steels and tailored blanks have been increasingly utilized with the aim to reduce parts weight and fuel consumptions. In the paper the mechanical properties and formability of tailored welded blanks made of a precipitation hardenable aluminum alloy but with different sheet thicknesses, have been investigated: both laser welding and friction stir welding have been developed to obtain the tailored blanks. For both welding operations a wide range of the thickness ratios has been considered. The formability of the obtained blanks has been characterized through tensile tests and cup deep drawing tests, in order to show the formability in dependency of the stress condition; what is more mechanical and metallurgical investigations have been made on the welded joints.

Moderate-duration static stretch reduces active and passive plantar flexor moment but not Achilles tendon stiffness or active muscle length

2009 ◽  
Vol 106 (4) ◽  
pp. 1249-1256 ◽  
Author(s):  
Anthony D. Kay ◽  
Anthony J. Blazevich
Keyword(s):  
Mechanical Properties ◽  
Achilles Tendon ◽  
Muscle Stiffness ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Static Stretch ◽  
Tendon Stiffness ◽  
Neuromuscular Activity ◽  
Time Motion ◽  
The Impact

The effects of static stretch on muscle and tendon mechanical properties and muscle activation were studied in fifteen healthy human volunteers. Peak active and passive moment data were recorded during plantar flexion trials on an isokinetic dynamometer. Electromyography (EMG) monitoring of the triceps surae muscles, real-time motion analysis of the lower leg, and ultrasound imaging of the Achilles-medial gastrocnemius muscle-tendon junction were simultaneously conducted. Subjects performed three 60-s static stretches before being retested 2 min and 30 min poststretch. There were three main findings in the present study. First, peak concentric moment was significantly reduced after stretch; 60% of the deficit recovered 30 min poststretch. This was accompanied by, and correlated with ( r = 0.81 ; P < 0.01) reductions in peak triceps surae EMG amplitude, which was fully recovered at 30 min poststretch. Second, Achilles tendon length was significantly shorter during the concentric contraction after stretch and at 30 min poststretch; however, no change in tendon stiffness was detected. Third, passive joint moment was significantly reduced after stretch, and this was accompanied by significant reductions in medial gastrocnemius passive muscle stiffness; both measures fully recovered by 30 min poststretch. These data indicate that the stretching protocol used in this study induced losses in concentric moment that were accompanied by, and related to, reductions in neuromuscular activity, but they were not associated with alterations in tendon stiffness or shorter muscle operating length. Reductions in passive moment were associated with reductions in muscle stiffness, whereas tendon mechanics were unaffected by the stretch. Importantly, the impact on mechanical properties and neuromuscular activity was minimal at 30 min poststretch.

scholarly journals The Promise of Youth Resistance Training

2021 ◽  
Vol 37 (02) ◽  
pp. 47-51
Author(s):  
Avery D Faigenbaum ◽  
Stephan Geisler
Keyword(s):  
Physical Activity ◽  
Resistance Training ◽  
Children And Adolescents ◽  
Vigorous Physical Activity ◽  
Temporal Trends ◽  
Developmentally Appropriate ◽  
Muscular Fitness ◽  
Exercise Interventions ◽  
Sport Activities ◽  
Building Activities

SummaryGlobal health reports indicate that a vast majority of children and adolescents are not accumulating the recommended amount of moderate to vigorous physical activity (MVPA) daily. This decline in MVPA has coincided with troubling temporal trends in muscular fitness in modern day youth. Since a prerequisite level of muscular strength is needed to move proficiently, developmentally appropriate interventions that target neuromuscular deficits are needed to prepare girls and boys for ongoing participation in active play, exercise and sport activities. Instead of focusing exclusively on aerobic activities, the promotion of youth physical activity should recognize the shared importance of strength, skill and aerobic activities for all youth regardless of body size or physical prowess. In addition to enhancing muscular fitness and improving motor skill performance, regular participation in resistance training has been found to have a favorable influence on musculoskeletal strength, cardiometabolic function, body composition, and mental health in children and adolescents. A new mindset that recognizes the critical importance of strength-building activities early in life is needed before this generation of girls and boys becomes resistant to exercise interventions later in life.

A pilot study of individualized exercise prescription to improve physical activity in cancer survivors.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e24030-e24030
Author(s):  
Priyanka Avinash Pophali ◽  
Urshila Durani ◽  
John Shin ◽  
Melissa C. Larson ◽  
Adam Shultz ◽  
...  
Keyword(s):  
Physical Activity ◽  
Pilot Study ◽  
Cardiac Rehabilitation ◽  
Cancer Survivors ◽  
Solid Tumor ◽  
Exercise Prescription ◽  
Exercise Session ◽  
Exercise Interventions ◽  
Time Points ◽  
Supervised Exercise

e24030 Background: Physical activity (PA) in cancer survivors improves quality of life (QOL), functioning, fatigue, and reduces the risk of treatment complications, cancer recurrence and death. However, the optimal intervention for increasing PA is not established. Most prospective studies have shown a 6-12-week program to be an effective intervention but this is often not feasible. Therefore, we piloted a one-time individualized exercise prescription in our cardiac rehabilitation center to improve PA in cancer survivors. Methods: We prospectively enrolled cancer survivors who had completed curative intent treatment, with no evidence of active disease in this pilot study. Survivors who consented underwent a consultation with an exercise physiologist for needs assessment followed by a supervised exercise session with a tailored exercise prescription. Survivors also filled out surveys assessing their PA and QOL at baseline (bl), 3, 6 and 12 months after intervention. Clinical information was collected via chart review. We estimated longitudinal PA score and change in PA using mixed models incorporating scores from all available time points using SAS (v 9.4). Results: Between May 2018 and January 2020, 50 participants (26 lymphoma and 24 solid tumor survivors) completed the intervention. 20% participants were on maintenance therapy during the study. Clinical characteristics of 42 evaluable participants are summarized in Table. The survey response rate was 82%, 58%, 58%, 46% at bl, 3, 6 and 12 months respectively. The level of PA improved with time [mean (SE) PA score: 58.5 (4.3) bl, 63.9 (4.8) at 3, 57.6 (4.8) at 6, 62.6 (5.3) at 12 months]. The change in PA from baseline to follow-up time-points [bl vs 3m p=0.41; bl vs 6m p=0.88; bl vs 12m p=0.55] or between the lymphoma and solid tumor survivors was not statistically significant and limited by sample size. No significant trend in QOL was seen. Conclusions: Individualized exercise prescription using the cardiac rehabilitation program may be a feasible, widely applicable tool to implement a PA intervention among cancer survivors. The trend towards improvement in PA in this novel one-time intervention provides intriguing evidence and deserves future study in larger sample sizes to understand if it can improve and create sustainable PA change comparable to longer term exercise interventions.[Table: see text]

scholarly journals Exercise tolerance during muscle contractions below and above the critical torque in different muscle groups

2018 ◽  
Vol 43 (2) ◽  
pp. 174-179 ◽  
Author(s):  
Leonardo Henrique Perinotto Abdalla ◽  
Benedito Sérgio Denadai ◽  
Natália Menezes Bassan ◽  
Camila Coelho Greco
Keyword(s):  
Exercise Intensity ◽  
Maximal Voluntary Contraction ◽  
Exercise Tolerance ◽  
Voluntary Contraction ◽  
Knee Extensors ◽  
Isometric Contractions ◽  
Plantar Flexors ◽  
Significant Difference ◽  
Muscle Groups

The objective of this study was to test the hypotheses that end-test torque (ET) (expressed as % maximal voluntary contraction; MVC) is higher for plantar flexors (PF) than knee extensors (KE) muscles, whereas impulse above ET (IET) is higher for KE than PF. Thus, we expected that exercise tolerance would be longer for KE than PF only during the exercise performed above ET. After the determination of MVC, 40 men performed two 5-min all-out tests to determine ET and IET. Eleven participants performed a further 4 intermittent isometric tests, to exhaustion, at ET + 5% and ET – 5%, and 1 test for KE at the exercise intensity (%MVC) corresponding to ET + 5% of PF. The IET (7243.2 ± 1942.9 vs. 3357.4 ± 1132.3 N·m·s) and ET (84.4 ± 24.8 vs. 73.9 ± 19.5 N·m) were significantly lower in PF compared with KE. The exercise tolerance was significantly longer for PF (300.7 ± 156.7 s) than KE (156.7 ± 104.3 s) at similar %MVC (∼60%), and significantly shorter for PF (300.7 ± 156.7 s) than KE (697.0 ± 243.7 s) at ET + 5% condition. However, no significant difference was observed for ET – 5% condition (KE = 1030.2 ± 495.4 s vs. PF = 1028.3 ± 514.4 s). Thus, the limit of tolerance during submaximal isometric contractions is influenced by absolute MVC only during exercise performed above ET, which seems to be explained by differences on both ET (expressed as %MVC) and IET values.

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