Muscle Strength In Healthy Subjects Research Articles

Validation of the Single Breath Count Test for Assessment of Inspiratory Muscle Strength in Healthy Subjects and People with Neuromuscular Disorders.

This study aimed to validate the single breath count test (SBCT) against volitional measures of respiratory muscle function in healthy subjects and people with neuromuscular disorders (NMD; n = 100 per group). Testing comprised upright and supine SBCT, forced vital capacity (FVC), maximum inspiratory pressure (MIP), and sniff nasal inspiratory pressure (SNIP). Predictability of FVC by SBCT was assessed using logarithmic regression analysis. Receiver operating characteristics curves were used to identify SBCT thresholds for lung restriction (FVC < 80% predicted), inspiratory muscle weakness (MIP < 60 cmH2O), and indication for non-invasive ventilation (NIV) in NMD patients. In both groups, SBCT showed moderate correlation with FVC. In patients, SBCT values were also correlated with MIP and SNIP. Strength of correlations was similar with supine and upright SBCT which accounted for 23.7% of FVC variance in healthy individuals (44.5% in patients). Predictive thresholds of upright SBCT were < 27 for MIP < 60 cmH2O (sensitivity 0.61/specificity 0.86), <39 for NIV indication (0.92/0.46), and <41 for FVC < 80% predicted (0.89/0.62). The SBCT is positively correlated with spirometry. It predicts both lung restriction and NIV indication in NMD patients. The SBCT allows for remote monitoring and may substitute for spirometry/manometry if appropriate devices are unavailable.

The Association Between Arterial Stiffness and Muscle Indices Among Healthy Subjects and Subjects With Cardiovascular Risk Factors: An Evidence-Based Review.

Skeletal muscle is one of the major tissues in the body and is important for performing daily physical activity. Previous studies suggest that vascular dysfunction contributes to reduced skeletal muscle mass. However, the association between vascular dysfunction and muscle mass, muscle strength and muscle flexibility are less established. Therefore, the focus of this review was to investigate the association between arterial stiffness (AS) which is a marker of vascular function, and muscle indices among healthy and those with cardiovascular risk factors. Three databases were used to search for relevant studies. These keywords were used: “arterial stiffness” OR “vascular stiffness” OR “aortic stiffness” OR “pulse wave velocity” OR “carotid femoral pulse wave velocity” OR “pulse wave analysis” AND “muscle” OR “skeletal” OR “flexibility” OR “range of motion” OR “articular” OR “arthrometry” OR “strength” OR “hand strength” OR “pinch strength” OR “mass” OR “lean” OR “body composition.” The criteria were; (1) original, full-text articles, (2) articles written in English language, (3) human studies involving healthy adults and/or adults with cardiovascular disease (CVD) or CVD risk factors (4) articles that reported the relationship between AS (measured as carotid-femoral pulse wave velocity or brachial-ankle pulse wave velocity) and muscle indices (measured as muscle mass, muscle flexibility and muscle strength) after adjusting for relevant confounders. The search identified 2295 articles published between 1971 and June 2021. Only 17 articles fulfilled the criteria. Two studies showed an inverse association between AS and muscle strength in healthy subjects, whereas in subjects with CVD risk factors, five out of seven studies found an inverse correlation between the two parameters. Eleven studies showed an inverse association between AS and muscle mass in subjects with CVD and CVD risk factors. The association between AS and muscle flexibility was not studied in any of the articles reviewed. In conclusion, there is an inverse correlation between muscle indices and AS in healthy adults and those with CVD or CVD risk factors. However, most of the studies were cross-sectional studies, hence the need for future prospective studies to address this issue.

The relationship between gluteus medius latent trigger point and muscle strength in healthy subjects

IntroductionWe hypothesized that latent MTrPs might decrease gluteus medius muscle strength in healthy individuals. This study aimed to investigate the relationship between latent MTrPs and gluteus medius muscle strength in a group of healthy adults. MethodsForty-eight healthy men were included in the study. Trigger point examination for the gluteus medius was performed bilaterally. Subjects with one or more trigger points on the dominant side and those without any trigger point were assigned to two groups. Muscle strength for the gluteus medius was assessed with a manual muscle tester using the “break test” technique on both sides. For statistical analysis, the independent sample t-test was used to compare the intergroup differences. ResultsThe latent MTrP group demonstrated lower abduction muscle strength in the dominant gluteus medius. Moreover, the latent MTrP group showed higher abduction muscle strength in the non-dominant gluteus medius (p < 0.05). Intergroup comparison revealed that gluteus medius abduction muscle strength on the dominant side was higher in the non-latent MTrP group (p < 0.05). ConclusionLatent MTrP may cause joint movement limitation, overload by affecting motor activation patterns and reciprocal inhibition mechanisms. Outcomes of the current study revealed that gluteus medius abduction strength values below 9.7 kg could be associated with latent MTrP with high sensitivity and low specificity. It is imperative to note that the latent MTrP of gluteus medius muscle, which has a critical role in the lumbopelvic junction, should not be ignored in clinical practice, and treatment should be applied when detected.

Effects of motor imagery combined with action observation training on the lateral specificity of muscle strength in healthy subjects.

Unilateral training of both lateral limbs increases unilateral muscle strength, whereas bilateral training increases bilateral muscle strength, a phenomenon known as lateral specificity in resistance training. Although motor imagery (MI) combined with action observation (AO) (i.e., MI + AO) training increases muscle strength, it is not completely understood whether such training increases the lateral specificity of muscle strength in a way resistance training does. To investigate whether MI + AO induces lateral specificity of muscle strength increase, 18 healthy subjects were divided into groups: MI + AO and the control groups. The control group watched a movie of natural sceneries for ten minutes per day five times a week for three weeks, whereas the MI + AO group imagined bilateral shoulder flexion while watching a movie of athletes performing bilateral shoulder flexion with barbells or dumbbells, with the same time schedule. The MI + AO group alone showed a significant increase in bilateral shoulder strength at three weeks after the intervention compared with the baseline. Unilateral shoulder strength was not significantly altered. These results suggest that MI + AO training increases muscle strength, providing evidence that similar to resistance training, lateral specificity also exists in MI + AO training.

The Reticulospinal Pathway Does Not Increase Its Contribution to the Strength of Contralesional Muscles in Stroke Survivors as Compared to Ipsilesional Side or Healthy Controls.

Startling acoustic stimulation (SAS), via activation of reticulospinal (RS) pathways, has shown to increase muscle strength in healthy subjects. We hypothesized that, given RS hyperexcitability in stroke survivors, SAS could increase muscle strength in stroke survivors. The objective was to quantify the effect of SAS on maximal and sub-maximal voluntary elbow flexion on the contralesional (impaired) side in stroke survivors as compared to ipsilesional (non-impaired) side and healthy controls. Thirteen hemiparetic stroke survivors and 12 healthy subjects volunteered for this investigation. Acoustic stimulation was given at rest, during ballistic maximal and sustained sub-maximal isometric elbow contractions using low (80 dB) and high intensity sound (105 dB). The effect of acoustic stimuli was evaluated from EMG and force recordings. Prevalence of acoustic startle reflex with shorter latency in the impaired biceps was greater as compared to the response in the non-impaired side of stroke subjects and in healthy subjects. Delivery of SAS resulted in earlier initiation of elbow flexion and greater peak torque in healthy subjects and in stroke subjects with spastic hemiplegia during maximal voluntary elbow flexion tasks. During sub-maximal elbow flexion tasks, SAS-induced force responses were slightly greater on the impaired side than the non-impaired side. However, no statistically significant difference was found in SAS-induced responses between impaired and non-impaired sides at maximal and sub-maximal elbow flexion tasks. The findings suggest RS hyperexcitability in stroke survivors with spastic hemiplegia. The results of similar SAS-induced responses between healthy and stroke subjects indicate that RS projections via acoustic stimulation are not likely to contribute to muscle strength for stroke survivors to a significant extent.

Effect of Kinesio taping on elbow muscle strength in healthy individuals: A randomized trial1.

The effect of the application of kinesiotape on muscle strength is still uncertain. This trial represents the first randomized-controlled trial to investigate the immediate and delayed effects of kinesiotape application on triceps muscle strength in healthy subjects. The trial was randomized and placebo-controlled. Young adult (18-35 years of age), healthy men were randomly assigned in a 1:1 ratio to either a kinesiotape group or a sham tape for the control group. ``Y''-shaped kinesiotape was applied to the triceps muscle in the sitting position. ``I''-shaped tape was used for the control group, and the sham tape was placed horizontally on the triceps muscle. A hand-held digital dynamometer was used to evaluate the peak force of elbow extension and flexion. Assessments were carried out before taping, an hour after taping, and after the first week. The mean ages of the participants in the kinesiotape and control groups were 26.2 ± 4.8 and 26.7 ± 4.8, respectively. The mean values of the peak force before taping, after the first hour, and after first week were statistically analyzed using one-way repeated measures. No statistical significance was found for in-group analysis of either the kinesiotape group or the control group (p> 0.05). In addition, there was no statistical significance in the between-group assessments (p> 0.05). The triceps muscle is appropriate for studying the effects of kinesiotape on muscle strength because elbow extension is provided by only one fusiform-shaped muscle. The results of this study did not show any significant changes in immediate or delayed muscle strength according to the initial measurements and between-group assessments.

The relationship between latent trigger point and muscle strength in healthy subjects: A double-blind study

Trigger points on the palpable taut bands of the muscles are promoted as an important cause of musculoskeletal pain. Our hypothesis was latent trigger points (LTrPs) could decrease muscle strength also in healthy people. The aim of our study was to investigate the relationship between LTrPs and muscle strength in a group of healthy adults. In total fifty healthy adults (20 women and 30 men) were included in the study. Trigger point examination for upper and middle trapezius, supraspinatus, serratus anterior and rhomboid major and minor were done bilaterally according to four criteria. Subjects who have at least two trigger points in dominant side were assigned to Group 1 (28 subjects), subjects who don't have any trigger points were assigned to Group 2 (23 subjects). Muscle strength for flexion and scaption was assessed with a Hand-Held Dynamometer (HHD) as break test on both sides. Both the subjects and the examiners were blind. For statistical analysis, independent sample t test was used to compare the differences between two groups. No significant differences were found in muscle strength between dominant and non-dominant sides in both groups (p >0.05). Significant difference was observed in both sides when comparison of muscle strength between Group 1 and 2, muscle strength was lower in subjects who had trigger points (p < 0.05). This study indicated that although there is not significant difference between dominant and non-dominant side, muscle strength is lower significantly in both %side sides in subjects who have trigger points in comparison with healthy subjects. Our results underline the importance of palpation of LTrPs in scapular and shoulder muscles in healthy subjects as they may contribute to the muscle strength. Further research is needed to facilitate a better understanding of the mechanism of LTrPs and to test the relationship with muscle strength.

Effects of a one-year exercise training program in adults over 70 years old: a study with a control group

Exercise training is known to improve exercise tolerance in elderly subjects. Therefore the present study aimed at investigating the effects of one year of combined endurance and resistance training in healthy older people. After baseline evaluation, subjects were assigned to either the training group (n=24, age 77.2+/-3.6) or the control group (n=16, age 76.1+/-4.8). Subjects in the control group did not change anything in their everyday activities, whereas subjects in the training group underwent moderately intensive combined exercise training, 3 hours a week over the course of one year. Breath-by-breath oxygen uptake and heart rate were measured at each workload during the symptom-limited cardiopulmonary exercise test. Performance on the 6-minute (6-MWT) and 200-meter (200-MWT) walk tests was registered and maximal strength was measured on knee extensor and plantar flexor muscles. After training, oxygen uptake was significantly increased, both at the ventilatory threshold (+11.6%, p<0.01) and at the end of exercise (+14.8%, p<0.001). The distance walked in 6 min (+10%, p<0.001), the time required to cover 200 m (-7.3%, p<0.001) and the maximal muscle strength (+15.2% and +17.4% for knee extensors and plantar flexors respectively, p<0.05) also improved after training. All these parameters had not significantly changed in the control group after the one-year period. The results of the present study show that one year of combined exercise training is well-tolerated and improves aerobic capacity, performance on field tests and muscle strength in healthy subjects over 70 years old.

Whistle mouth pressure as test of expiratory muscle strength.

Expiratory muscle strength is a determinant of cough function. Mouth pressures during a maximal static expiratory effort (PE,max) are dependent on patient motivation and technique and low values are therefore difficult to interpret. This study hypothesized that a short, sharp and maximal expiration through a narrow aperture, a "whistle", might provide a complementary test of expiratory muscle strength. To obtain a maximal whistle, subjects (27 healthy volunteers and 10 patients with amyotrophic lateral sclerosis) were asked to perform a short, sharp blow as hard as possible, from total lung capacity, through a reversed paediatric inhaler whistle, connected to a flange-type mouthpiece. In both healthy subjects and patients, whistle mouth pressure (Pmo,W) was closely related to the pressure measured in the oesophagus and stomach during the same manoeuvre. In healthy subjects, Pmo,W and PE,max correlated with wide limits of agreement, although Pmo,W values were significantly higher than PE,max (131+/-31 cmH2O versus 101+/-27 cmH2O, p<0.0001). In patients, it was also found that Pmo,w and PE,max values were strongly related (r=0.937, p<0.0001). In healthy subjects, the intraclass correlation coefficient and the variation coefficient for Pmo,W repeated measurements were respectively 0.88 and 7.0%. However Pmo,W and PE,max were always smaller than the gastric pressure generated by a maximal cough. It is concluded that mouth whistle pressure, a noninvasive, reproducible and simple test, provides a reliable measure of expiratory muscle strength in healthy subjects that is acceptable to patients and can be used in a complementary fashion to maximal static expiratory effort.