Strength In Healthy Adults Research Articles

The effect of an anti-slip surface on objective measures of tongue strength in healthy adults

Purpose: Instrumental assessments of tongue strength have provided clinicians with the ability to obtain quantitative measures to document lingual weakness. A technical challenge with a common instrument is that the surface of the of the bulb-shaped sensor is smooth and can be slippery when contacted by the tongue. This study evaluated whether adding a textured layer to the bulb leads to enhanced strength measures in neurologically normal adults. Methods: Maximum-effort maneuvers for anterior and posterior tongue elevation, right and left tongue lateralization, and tongue protrusion were available from 62 healthy adults using the Iowa Oral Performance Instrument (IOPI). The IOPI tongue bulb was either bare or covered with a single layer of gauze. The maximum pressure (Pmax) exerted on the bulb from three trials was used as the outcome variable for each task. Results: In addition to significant main effects for both bulb-cover and task, there was a significant interaction between the use of gauze and the direction of the tongue-strength maneuver. Pmax was significantly greater when a gauze-covered bulb was used for tongue lateralization and protrusion but not for tongue elevation maneuvers. Conclusion: Using a single-layer of gauze on the smooth tongue-bulb helped reduce slippage of the tongue and resulted in greater Pmax values when evaluating tongue strength in the lateral and protrusive directions, but not for tongue elevation. Efforts to develop a more permanent solution to texturizing the bulb’s surface are needed.

THE RELATIONSHIP BETWEEN SINGLE LEG BALANCE AND ISOMETRIC ANKLE AND HIP STRENGTH IN A HEALTHY POPULATION.

Impaired balance and strength commonly affect athletes with conditions like chronic ankle instability (CAI). Yet, clinical research surrounding the relationship between balance, strength, and CAI is still growing. Deeper investigation of these relationships is warranted to better inform clinical practice patterns when managing athletes with balance deficits. To investigate the relationship between single leg balance, ankle strength, and hip strength in healthy, active adults. Observational study. Forty healthy participants (age 23.7 ± 4.9 years) were assessed for static balance, using a modified version of the Balance Error Scoring System (mBESS), as well as isometric strength of ankle and hip musculature via handheld dynamometry. Pearson's correlations were used to analyze relationships between balance and strength measures. Paired t-tests were utilized to compare dominant and non-dominant limb performance. Negligible to low, negative correlations were found between balance scores and hip extension strength (r = -0.24 to -0.38, p<0.05). High, positive correlations were found between ankle and hip strength measures (r = 0.75 to 0.84, p<0.05). When comparing dominant to non-dominant limbs, only minimal differences were noted in ankle eversion strength (mean difference = 6.0%, p<0.01) and hip extension strength (mean difference = 5.5%, p<0.01). Minimal relationships were identified between static balance and isometric ankle and hip strength. Comparison of dominant and non-dominant limbs suggests that clinicians should expect relative symmetry in balance and strength in healthy adults. Thus, asymmetries found during clinical examination should raise suspicion of specific impairments that may lead to dysfunction. 2c.

Prediction equation of hip external rotators maximum torque in healthy adults and older adults using the measure of hip extensors maximum torque

BackgroundThe use of predictive equation of muscular torque can reduce physical effort and time spent during evaluation. ObjectivesTo establish, validate, and test the accuracy of a prediction equation to estimate the hip external rotators (HER) torque in adults and older adults by means of hip extensors (HEX) torque measurement. MethodsEighty-three healthy adults (development set) were assessed to test the association of HEX and HER torques and to establish the prediction equation. A separate 36 adults and 15 older adults (validation sets) were assessed to test the ability of the equation to estimate HER torque. Hip isometric strength was assessed by a handheld dynamometer. ResultsSimple linear regression analysis revealed that HEX torque was associated with HER torque (r=0.80; p<0.0001), resulting in the following prediction equation: HERtorque=−0.02+(0.58 * HEXtorque). Paired t-test revealed no difference between directly measured and predicted values of HER torque in adults (mean difference=0.02; 95% CI=−0.115, 0.072) and older adults (mean difference=0.05; 95% CI=−0.02, 0.12). ConclusionThe HEX and HER torques were strongly correlated. The prediction equation was valid, accurate, and can be used to estimate HER muscle strength in healthy adults and older adults, requiring only the direct measurement of HEX torque.

Effect of tongue-to-palate resistance training on tongue strength in healthy adults

ObjectiveTongue strength is crucial for safe and efficient oropharyngeal swallowing. This study examined the effect of tongue-to-palate resistance training (TPRT) on anterior and posterior tongue strength by conducting a prospective, randomized, parallel allocation trial. MethodsNinety-one healthy adults were recruited in this study and were randomly assigned to an experimental group (n = 44) or a control group (n = 47). The experimental group performed TPRT for 8 weeks (5 days per week), whereas the control group performed the usual daily activities. Tongue strength was measured using the Iowa Oral Performance Instrument (IOPI) before and after the practice program was conducted at weeks 2, 4, 6, and 8, to evaluate the feasibility of the developed training protocol. ResultsThis experimental group demonstrated more improvements in both anterior tongue strength (p < .05) and posterior tongue strength (p < .05). The positive effects of the intervention on tongue strength appeared at 8 weeks for the anterior region and 2 weeks for the posterior region. ConclusionsThese findings illustrate that TPRT can improve tongue strength. It is suggested that people integrate this exercise protocol into their daily life, positive change in tongue strength may prevent or halt presbyphagia.

Relationships between Foot Morphology and Foot Muscle Strength in Healthy Adults.

The purpose of this study was to investigate if measurements of foot morphology in sitting and standing positions can predict foot muscle strength. Twenty-six healthy male adults were recruited, and their foot morphology and foot muscle strength were measured. Foot morphological variables, toe flexor strength, and metatarsophalangeal joint flexor strength were measured by using a digital caliper, Ailitech-AFG500 dynameter and metatarsophalangeal joint flexor strength tester, respectively. Partial correlation and multivariate stepwise regression were used to explore the relationships between foot morphology and toe/metatarsophalangeal joint strength. Results adjusted by age and body mass index were as follows: (1) truncated foot length in sitting and standing positions and foot width in standing position were positively correlated with the flexor strength of the first toe; (2) foot length, foot width, and truncated foot length in both positions were positively related to the flexor strength of the other toes; (3) arch height index in sitting position and differences in navicular height were negatively associated with the flexor strength of the other toes; (4) differences in foot width were negatively associated with metatarsophalangeal joint flexor strength; and (5) the multivariate stepwise regression model showed that truncated foot length in sitting position, navicular height in standing position, differences in navicular height, foot width in sitting position, and differences in foot width were significantly correlated with toe/metatarsophalangeal joint flexor strength. Simple measurements of foot morphological characteristics can effectively predict foot muscle strength. Preliminary findings provided practical implications for the improvement of the foot ability by making specific foot muscle training sessions in professional sports and by compensating the predicted muscle strength defects to prevent foot injury.

Combined protein and calcium \u03b2-hydroxy-\u03b2-methylbutyrate induced gains in leg fat free mass: a double-blinded, placebo-controlled study

BackgroundThe leucine metabolite β-hydroxy-β-methylbutyrate (HMB) is widely used as an ergogenic supplement to increase resistance-training induced gains in fat free mass (FFM) and strength in healthy adults. Recent studies have questioned the effectiveness of HMB, particularly when a high protein diet is habitually consumed. To investigate the additive resistance-training induced effects of HMB and protein in untrained individuals, we conducted a randomized double-blind, placebo-controlled study that compared the effects of combined protein and HMB supplementation to protein supplementation alone on FFM and muscle strength after 12-week resistance training.MethodsSixteen healthy men (22 ± 2 yrs) performed a periodized resistance-training program for twelve weeks (four sessions per week). The program comprised two mesocycles, characterized by a linear periodization and non-linear periodization, respectively, and separated by a 1-week tapering period. All participants received 60 g of whey protein on training days and 30 g of whey protein (WP) on non-training days. Participants were randomly assigned to additionally receive 3 g of calcium HMB (WP + HMB) or a placebo (WP + PLA). Body composition and physical fitness were tested before and after the 12-week training program. Whole-body and arm and leg fat free mass (FFM) were assessed by bioimpedance spectroscopy; upper arm and leg fat free cross sectional areas were also quantified using magnetic resonance imaging (MRI); upper and lower body strength were measured by One-repetition maximum (1-RM) bench press and leg press.ResultsWhole-body and segmental FFM increased in both groups (P < 0.001). However, gains in leg FFM were higher in WP + HMB vs. WP + PLA (arm FFM: + 6.1% vs. + 9.2%, P = 0.2; leg FFM: + 14.2% vs. + 7.0%, P < 0.01). No change in fat mass was observed (P = 0.59). 1-RM increased in both groups (P < 0.001).ConclusionsCombined protein and HMB supplementation resulted in segmental, but not whole-body increases in FFM compared to protein supplementation alone. These findings could explain some of the controversial effects of HMB reported in previous studies and have practical implications for maximizing training-induced gains in FFM and clinical conditions associated with skeletal muscle deconditioning such as aging, sedentary lifestyles, bed rest and spaceflight.

Effects of plyometric training on jumping, sprint performance, and lower body muscle strength in healthy adults: A systematic review and meta-analyses.

To determine the effect of lower body plyometric training (PLY) on jumping, sprint performance, and lower body muscle strength in healthy adults. A systematic literature search (PubMed, Embase) was performed. Studies were included if they (a) described a lower body PLY intervention lasting ≥4weeks; (b) included measures of jumping, sprint, and/or lower body muscle strength; (c) included healthy individuals ≥18years; (d) included a training or non-training control group; and (e) were written in English. Meta-analyses identifying the effects of PLY on jumping, sprint, and lower body muscle strength were conducted providing the standardized mean difference (SMD). A total of 826 records were identified of which 25 fulfilled the inclusion criteria, yielding 19, 11, and seven data points for the meta-analyses of jumping, sprint performance, and lower body muscle strength, respectively. The data showed improvements for all three performance variables after 4-12weeks of PLY. The SMD (CI95%) across studies for jump height, sprint time, and muscle strength were 0.45 (0.16: 0.75), -0.59 (-1.01: -0.17), and 0.33 (0.03: 0.63), respectively, where the latter two showed within-sample heterogeneity. The systematic review and meta-analyses showed that PLY elicits a small-to-moderate positive effect on jumping, sprint performance, and lower body muscle strength in healthy adults being recreationally active or athletes.

Experimentally quantifying the feasible torque space of the human shoulder

Daily tasks rely on our ability to generate multi-dimensional shoulder torques. When function is limited, strength assessments are used to identify impairments and guide treatment. However, these assessments are often one-dimensional and limited in their sensitivity to diagnose shoulder pathology. To address these limitations, we have proposed novel metrics to quantify shoulder torque capacity in all directions. To quantify the feasible torque space of the shoulder, we measured maximal volitional shoulder torques in 32 unique directions and fit an ellipsoid model to these data. This ellipsoid model was used to quantify overall strength magnitude, strength balance, and the directions in which participants were strongest and weakest. We used these metrics to characterize three-dimensional shoulder strength in healthy adults and demonstrated their repeatability across days. Finally, using musculoskeletal simulations, we showed that our proposed metrics can distinguish between changes in muscle strength associated with aging or rotator cuff tears and quantified the influence of altered experimental conditions on this diagnostic capacity. Our results demonstrate that the proposed metrics can robustly quantify the feasible torque space of the shoulder and may provide a clinically useful description of the functional capacity of the shoulder in health and disease.

Leg Dominance Effect on Isokinetic Muscle Strength of Hip Joint

ObjectiveThe purpose of this study was to compare the isokinetic strength of hip muscles in dominant vs nondominant legs in healthy adults. MethodsThirty-two healthy college students (15 male and 17 female) volunteered to participate in this study. A Biodex system 3 was used to measure isokinetic peak torque at an angular velocity of 60°/s for the hip flexors, extensors, abductors, and adductors in both dominant and nondominant legs. Hip flexors and extensors were tested from the supine lying position while hip abductors and adductors were tested from the side lying position using concentric mode of muscle contraction. ResultsThere were no statistically significant differences between the dominant and nondominant sides for all tested hip muscles. ConclusionLeg dominance does not appear to affect hip muscle strength in healthy adults. This may be used as normative data for those with differences in muscle strength between involved and uninvolved sides.

Urinary Sex Steroid and Glucocorticoid Hormones Are Associated With Muscle Mass and Strength in Healthy Adults.

Sex steroid hormones exhibit anabolic effects whereas a deficiency engenders sarcopenia. Moreover, supraphysiological levels of glucocorticoids promote skeletal muscle atrophy, whereas physiologic levels of glucocorticoids may improve muscle performance. To study the relationship between both groups of steroid hormones at a physiological range with skeletal muscle mass and function in the general population. Cross-sectional analysis of the associations between urinary excreted androgens, estrogens, glucocorticoids, and steroid hormone metabolite ratios with lean mass and handgrip strength in a population-based cohort. Three centers in Switzerland including 1128 participants. Urinary steroid hormone metabolite excretion by gas chromatography-mass spectrometry, lean mass by bioimpedance analysis, and isometric handgrip strength by dynamometry. For lean mass a strong positive association was found with 11β-OH-androsterone and with most glucocorticoids. Androsterone showed a positive association in middle-aged and older adults. Estriol showed a positive association only in men. For handgrip strength, strong positive associations with androgens were found in middle-aged and older adults, whereas positive associations were found with cortisol metabolites in young to middle-aged adults. Sex steroids and glucocorticoids are strongly positively associated with skeletal muscle mass and strength in the upper limbs. The associations with muscle strength appear to be independent of muscle mass. Steroid hormones exert age-specific anabolic effects on lean mass and handgrip strength. Deficits in physical performance of aged muscles may be attenuated by androgens, whereas glucocorticoids in a physiological range increase skeletal muscle mass at all ages, as well as muscle strength in particular in younger adults.

Upper-Body Exercises With External Resistance Are Well Tolerated and Enhance Muscle Activity in People With Hemophilia.

Conventional nonresisted therapeutic exercises for people with hemophilia involve a careful, low-intensity approach to avoid injuries. Externally resisted exercise is highly efficient for increasing muscle strength in healthy adults but its feasibility for people with hemophilia remains unknown. The purpose of this study was to evaluate muscle activity during upper-body rehabilitation exercises with 2 types of external resistance and without external resistance (conventional) and to examine tolerability, kinesiophobia, and possible adverse effects derived from the session. This was a cross-sectional study. Twelve people with hemophilia A/B (11 with severe hemophilia undergoing prophylactic treatment, 1 with mild hemophilia) participated. During the experimental session, participants completed the Tampa Scale of Kinesiophobia and performed 2 exercises-elbow flexion and shoulder abduction-with 3 conditions for each exercise: elastic resistance (externally resisted), free weights (externally resisted), and conventional nonresisted. Surface electromyography signals were recorded for the biceps brachii, triceps brachii, upper trapezius, and middle deltoid muscles. After the session, exercise tolerability and kinesiophobia were assessed. Adverse effects were evaluated 24 and 48 hours after the session. Externally resisted exercises provided greater muscle activity than conventional nonresisted therapeutic exercises. The exercises were generally well tolerated and there was no change in kinesiophobia following the session. No adverse effects were observed in the following days. Small sample size was the main limitation. In people with severe hemophilia undergoing prophylactic treatment, elbow flexion and shoulder abduction exercises with external resistance at moderate intensities are feasible and provide greater muscle activity than nonresisted conventional exercises.

Short-term H2 inhalation improves running performance and torso strength in healthy adults.

In this randomized, double-blind, placebo-controlled, crossover pilot trial, we evaluated the effects of 7-day H2 inhalation on exercise performance outcomes and serum hormonal and inflammation profiles in a cohort of young men and women. All participants (age 22.9 ± 1.5 years; body mass index 23.4 ± 2.5 kg m-2; 10 women and 10 men) were allocated to receive either gaseous hydrogen (4%) or placebo (room air) by 20-min once-per-day inhalation for 7 days, with a wash-out period of 7 days to prevent the residual effects of interventions across study periods. The primary treatment outcome was the change in running time-to-exhaustion in the incremental maximal test from baseline to day 7. Additionally, assessment of other exercise performance endpoints and clinical chemistry biomarkers was performed at baseline and at 7 days after each intervention. The trial was registered at ClinicalTrials.gov (ID NCT03846141). Breathing 4% hydrogen for 20 min per day resulted in increased peak running velocity (by up to 4.2%) as compared to air inhalation (P = 0.05). Hydrogen inhalation resulted in a notable drop in serum insulin-like growth factor 1 (IGF-1) by 48.2 ng/mL at follow-up (95% confidence interval [CI]: from -186.7 to 89.3) (P < 0.05), while IGF-1 levels were elevated by 59.3 ng/mL after placebo intervention (95% CI; from -110.7 to 229.5) (P < 0.05). Inhalational hydrogen appears to show ergogenic properties in healthy men and women. Gaseous H2 should be further evaluated for its efficacy and safety in an athletic environment.

Influence of the asymmetric tonic neck reflex on handgrip strength in healthy adults

BACKGROUND: Primitive reflexes are stereotypic motor behavioral responses that are necessary for the normal development of infants. Retention of these reflexes is mostly pathological and can lead to developmental delays. Few reflexes are also seen in normal adults, and the influence of the retained reflexes on functional activities is evident. This study identified the effect of the asymmetric tonic neck reflex (ATNR) on handgrip. MATERIALS AND METHODS: One hundred adults within the age group of 18–25 were selected for the study. Handgrip strength was measured using hand-held dynamometer on the dominant hand in three different neck positions, neck in neutral, neck actively rotated to the right, and rotated to the left. Data collected were statistically analyzed to identify the difference between the three mean values. RESULTS: The Friedman test performed to analyze the handgrip strength between the groups of three head positions demonstrated a statistically significant difference, χ2 = 110.479, P = 0.000. Post hoc analysis with the Wilcoxon signed-rank tests was conducted with a Bonferroni correction applied, resulting in a significant level set at P < 0.017. There was a significant difference in the handgrip measured between the group of head rotated to the left with head in neutral (P = 0.000) and head rotated to the right and the left (P = 0.000), but failed to demonstrate a significant difference between the groups of head in neutral and head rotation to right (P = 0.041). The results of this study thus infer a significant increase in handgrip of the right hand when head is rotated toward the left side. CONCLUSION: The study identified that there is an increased handgrip power on the dominant side when the head is rotated to the opposite side. This can be attributed to the increased flexor tone due to the retained effects of ATNR. Effects of ATNR can be seen in normal adults while assessing handgrip strength. This must be taken into consideration while assessing the same during diagnostic, prognostic, and rehabilitation purposes.

Relationship of Circulating Growth and Differentiation Factors 8 and 11 and Their Antagonists as Measured Using Liquid Chromatography-Tandem Mass Spectrometry With Age and Skeletal Muscle Strength in Healthy Adults.

Growth and differentiation factors 8 (GDF8) and 11 (GDF11) have attracted attention as targets for rejuvenating interventions. The biological activity of these proteins may be affected by circulating antagonists such as their respective prodomains, follistatin (FST315), WFIKKN1, and WFIKKN2. Reports of the relationship of GDF8 and GDF11 and their antagonists with aging and aging phenotypes such as skeletal muscle strength have been conflicting possibly because of difficulties in measuring these proteins and polypeptides. Plasma GDF8 and GDF11 and their antagonists were measured using a multiplexed selected reaction monitoring assay and liquid chromatography-tandem mass spectrometry in 160 healthy adults aged 22-93 years. Quadriceps strength was measured by knee extensor torque using isokinetic dynamometry. Spearman correlations with age were the following: GDF11 prodomain (r = .30, p = .001), GDF11 mature protein (r = .23, p = .004), FST315 (r = .32, p < .0001), WFIKKN1 (r = -.21, p = 0.008), and WFIKKN2 (r = .18, p = .02). Independent of age, FST315 and WFIKKN1 were negatively associated with knee strength (p = .02, p = .03, respectively) in a multivariable model that included both GDF8 and GDF11 mature proteins. When measured by an antibody-free selected reaction monitoring assay, GDF8, GDF11, and their antagonists are found in the circulation in the ng/mL range. In healthy adults, plasma GDF11 and antagonists FST315, WFIKKN1, and WFIKKN2 differed by age. Antagonists of GDF8 and GDF11, but not GDF8 and GDF11, were independently associated with skeletal muscle strength. Further work is needed to characterize the relationship of these protein and polypeptides with sarcopenia-related phenotypes such as physical function and walking disability.

The influence of kinesiology tape colour on performance and corticomotor activity in healthy adults: a randomised crossover controlled trial

BackgroundThere exists conflicting evidence regarding the impact of kinesiology tape on performance and muscle function. One variable that may account for disparities in the findings of previous studies is the colour of the tape applied. Colour is hypothesised to influence sporting performance through modulation of arousal and aggression. However, few studies have investigated the influence of colour on products designed specifically to enhance athletic performance. Further, no studies have investigated the potential influence of colour on other drivers of performance, such as corticomotor activity and neuromuscular function. Thus, the aim of this study was to investigate the influence of kinesiology tape colour on athletic performance, knee extensor torque, and quadriceps neuromuscular function.MethodsThirty two healthy participants were assessed under five conditions, applied in random order: (1) no kinesiology tape (control), (2) beige-coloured kinesiology tape applied with tension (sham A), (3) beige-coloured kinesiology tape applied with no tension (sham B), (4) red-coloured kinesiology tape applied with tension, and (5) blue-coloured kinesiology tape applied with tension. Athletic performance was assessed using a previously validated hop test, knee extensor torque was measured using an isokinetic dynamometer, and transcranial magnetic stimulation was utilised to provide insight into the neuromuscular functioning of the quadriceps musculature.ResultsKinesiology tape had no beneficial impact on lower limb performance or muscle strength in healthy adults. The colour of the tape did not influence athletic performance (F (4, 120) = 0.593, p = 0.669), quadriceps strength (F (4, 120) = 0.787, p = 0.536), or neuromuscular function (rectus femoris: F (2.661, 79.827) = 1.237, p = 0.301).ConclusionThis study found that kinesiology tape does not alter lower limb performance or muscle function in healthy adults, irrespective of the colour of the tape applied. Future research should seek to confirm these findings beyond the research setting, across a range of sports, and at a range of skill levels.Trial registrationAustralian New Zealand Clinical Trials Registry. ACTRN12616001506482. Prospectively registered on 01/11/2016.

Normative values of isometric elbow strength in healthy adults: a systematic review.

Post-traumatic deformities such as biceps tendon rupture or (peri-)articular fractures of the elbow are often related to a decrease in muscle strength. Postoperative evaluation of these deformities requires normative values of elbow strength. The purpose of this systematic review was to determine these normative values of isometric elbow strength in healthy adults resulting from studies evaluating this strength (i.e. flexion, extension, pronation and supination strength). The databases of PubMed, EMBASE and Web of Sciences were searched and screened for studies involving the isometric elbow strength as measured in asymptomatic volunteers. The quality of the studies was assessed and studies of low quality were excluded. Nineteen studies met the inclusion criteria and were of sufficiently high quality to be included in the present review. In these studies, elbow strength was measured in a total of 1880 healthy volunteers. The experimental set-up and devices used to measure elbow strength varied between studies. Using some assumptions, a normative values table was assembled. Large standard deviations of normative values in combination with different measurement devices used, as well as the different measurement positions of the subjects, demonstrated that there is no consensus about measuring the isometric elbow strength and therefore the normative values have to be interpreted with caution.

Measuring intrinsic hand strength in healthy adults: The accuracy intrarater and inter-rater reliability of the Rotterdam Intrinsic Hand Myometer

Study DesignClinical measurement study. IntroductionMeasuring the isometric strength generated during isolated hand joint motions is a challenging feat. The Rotterdam Intrinsic Hand Myometer (RIHM; med.engineers, Rotterdam, Netherlands) permits measurement of isolated movements of the hand. To date, there is limited evidence on the inter-rater reliability and limited adult normative data of RIHM. Given that multiple raters, often with varying degrees of experience, are needed to collect normative data, inter-rater reliability testing and a comparison of novice and experienced raters are needed. Purposes of the StudyThe purposes of this study were to test the accuracy, intrarater reliability, and inter-rater reliability of the RIHM in healthy-handed adults. MethodsRIHM accuracy was tested through use of precision class F weights. Adults 18 years or older without upper limb dysfunction were recruited. Each participant was tested by 4 raters, 3 occupational therapy graduate students, and an experienced certified hand therapist, through use of a calibrated RIHM. Five strength measures were tested bilaterally (ie, thumb carpometacarpal palmar abduction, index finger metacarpophalangeal [MP] abduction, index finger MP flexion, thumb MP flexion, and small finger MP abduction) 3 times per a standardized protocol. Statistical methods were used to test accuracy, inter-rater reliability, and intrarater/response stability. ResultsThe accuracy of RIHM device error was 5% or less. Reliability testing included the participation of 19 women and 10 men (n = 29). All raters were in excellent agreement across all muscles (intraclass correlation coefficient, ≥0.81). Low standard error of measurement values of ≤8.3 N (1.9 lb) across raters were found. The response stability and/or intrarater reliability of the novice and certified hand therapist raters were not statistically different. DiscussionThe RIHM has an acceptable instrument error; the RIHM and its standardized procedure have excellent inter-rater reliability and response stability when testing those without hand limitations; and the response stability and/or intrarater reliability of expert and novice raters were consistent. ConclusionsThe use of the RIHM is justified when multiple raters of varying expertise collect normative data or conduct cohort studies on persons with healthy hands. Future research is warranted. Level of EvidenceNot applicable.

The influence of resting blood pressure on muscle strength in healthy adults.

Adverse alterations in the skeletal muscle response to exercise have been noted among adults with hypertension. The influence of resting blood pressure (BP) on muscle strength is unknown. We hypothesized that adults with high BP would exhibit lower muscular strength than adults with normal BP. An isokinetic dynamometer tested 21 measures of isometric and isokinetic muscle strength. BP was measured by auscultation. Patients were categorized into having normal (<120 and <80 mmHg) or high (≥120 and/or ≥80 mmHg) BP. Height (cm) and weight (kg) were measured to calculate BMI (kg/m). Analysis of covariance tested differences in muscle strength between BP groups with sex, age, and height as covariates. Patients [420 (49%) men] were middle-aged (44.1±16.1 years) and overweight (26.4±4.8 kg/m) with 187 having normal (107.7±7.3/68.3±6.3 mmHg) and 233 having high (127.8±9.8/80.8±8.1 mmHg) BP. For upper body, three of five extension measures and five of five flexion measures, as well as handgrip, were greater in the high than the normal BP group (P≤0.05). For lower body, five of five extension measures were greater in the high than the normal BP group, whereas there were no differences between BP groups for the five flexion measures (P>0.05). Contrary to our hypothesis, adults with high BP displayed greater muscle strength than adults with normal BP. Reasons for our findings are unclear, but may be because of shifts in muscle fiber type from type I to type IIb/x and oxidative to glycolytic metabolism; alterations may result in a more strength-adapted phenotype among adults with high BP such as we observed.

Methylphenidate Modulates Functional Network Connectivity to Enhance Attention.

Recent work has demonstrated that human whole-brain functional connectivity patterns measured with fMRI contain information about cognitive abilities, including sustained attention. To derive behavioral predictions from connectivity patterns, our group developed a connectome-based predictive modeling (CPM) approach (Finn et al., 2015; Rosenberg et al., 2016). Previously using CPM, we defined a high-attention network, comprising connections positively correlated with performance on a sustained attention task, and a low-attention network, comprising connections negatively correlated with performance. Validating the networks as generalizable biomarkers of attention, models based on network strength at rest predicted attention-deficit/hyperactivity disorder (ADHD) symptoms in an independent group of individuals (Rosenberg et al., 2016). To investigate whether these networks play a causal role in attention, here we examined their strength in healthy adults given methylphenidate (Ritalin), a common ADHD treatment, compared with unmedicated controls. As predicted, individuals given methylphenidate showed patterns of connectivity associated with better sustained attention: higher high-attention and lower low-attention network strength than controls. There was significant overlap between the high-attention network and a network with greater strength in the methylphenidate group, and between the low-attention network and a network with greater strength in the control group. Network strength also predicted behavior on a stop-signal task, such that participants with higher go response rates showed higher high-attention and lower low-attention network strength. These results suggest that methylphenidate acts by modulating functional brain networks related to sustained attention, and that changing whole-brain connectivity patterns may help improve attention. Recent work identified a promising neuromarker of sustained attention based on whole-brain functional connectivity networks. To investigate the causal role of these networks in attention, we examined their response to a dose of methylphenidate, a common and effective treatment for attention-deficit/hyperactivity disorder, in healthy adults. As predicted, individuals on methylphenidate showed connectivity signatures of better sustained attention: higher high-attention and lower low-attention network strength than controls. These results suggest that methylphenidate acts by modulating strength in functional brain networks related to attention, and that changing whole-brain connectivity patterns may improve attention.

Test-retest reproducibility and validity of the back-leg-chest strength measurements

BACKGROUND: A single measure to characterize overall muscle strength is advantageous because it saves time and costs of evaluation. For this reason, the back-leg-chest (BLC) strength might be an appropriate single measure in characterizing total body strength. OBJECTIVE: To assess the test-retest reproducibility and smallest real difference (SRD) of the BLC dynamometer in healthy adults and adolescents and to examine whether handgrip, knee-extensor and knee-flexor strength predict BLC strength in healthy adults. METHODS: Forty-five adults and 58 adolescents were recruited. In a first session back-leg-chest strength, handgrip strength, and additionally, in adults, isometric knee-extensor strength, and knee-flexor strength were measured. In a second session, 2–5 days later, BLC strength was measured again for test-retest reproducibility. RESULTS: Inter-session correlations of BLC strength were high (all r’s and ICC’s > 0.92). Bland-Altman-plots showed high agreement. The SRD and SRD% were between 14–26, and 19% and 26% respectively. Strength variables (handgrip, kneeextensor, and knee-flexor strength) explained 87% of the variance in BLC strength. A stepwise linear regression showed that dominant knee extensor and flexor strength were the most important significant predictors of BLC strength (r 2 = 0.86). CONCLUSIONS: This study demonstrated that the BLC dynamometer has reasonably high test-retest reproducibility and hence may serve in some pertinent situations to be an appropriate tool for clinical, basic and applied research.