Isometric Elbow Flexion Strength Research Articles

Does the Effect of Mental Fatigue Created by Motor Imagery on Upper Extremity Functions Change with Diaphragmatic Breathing Exercises? A Randomized, Controlled, Single-Blinded Trial.

Background and Objectives: This study focused on the impact of mental fatigue induced by motor imagery on upper limb function, an area with limited research compared to lower limb performance. It aimed to explore how diaphragmatic breathing exercises influence these effects. Materials and Methods: This study included 30 participants, and Group 1 participated in 12 sessions of diaphragmatic breathing exercises under the supervision of a physiotherapist; Group 2 did not receive any intervention. For all the participants, mental fatigue was induced with motor imagery before and after the intervention, and evaluations were performed before and after mental fatigue. Upper extremity functions were evaluated using isometric elbow flexion strength, hand grip strength, upper extremity reaction time and endurance, finger reaction time, the nine-hole peg test, shoulder position sense, light touch-pressure threshold, and two-point discrimination. Results: The study results showed that after mental fatigue, there was a decrease in isometric elbow flexion strength, nondominant hand grip strength, and nondominant upper extremity endurance, and an increase in nondominant tactile sensation (p < 0.05). No changes were found in two-point discrimination, nine-hole peg test time, and position sense on either side (p > 0.05). The effect of mental fatigue on isometric elbow flexion strength and nondominant grip strength showed significant improvement following diaphragmatic breathing exercises (p < 0.05). Conclusions: This study found that mental fatigue from motor imagery can impact elbow flexion, hand grip strength, upper extremity endurance, and tactile sensitivity. Breathing exercises may help improve strength parameters affected by mental fatigue. It is crucial to consider these effects on upper extremity functions in rehabilitation programs.

Differential effects of attentional focus strategies during long-term resistance training

The purpose of this study was to investigate the effects of using an internal versus external focus of attention during resistance training on muscular adaptations. Thirty untrained college-aged men were randomly assigned to an internal focus group (INTERNAL) that focused on contracting the target muscle during training (n = 15) or an external focus group (EXTERNAL) that focused on the outcome of the lift (n = 15). Training for both routines consisted of 3 weekly sessions performed on non-consecutive days for 8 weeks. Subjects performed 4 sets of 8–12 repetitions per exercise. Changes in strength were assessed by six repetition maximum in the biceps curl and isometric maximal voluntary contraction in knee extension and elbow flexion. Changes in muscle thickness for the elbow flexors and quadriceps were assessed by ultrasound. Results show significantly greater increases in elbow flexor thickness in INTERNAL versus EXTERNAL (12.4% vs. 6.9%, respectively); similar changes were noted in quadriceps thickness. Isometric elbow flexion strength was greater for INTERNAL while isometric knee extension strength was greater for EXTERNAL, although neither reached statistical significance. The findings lend support to the use of a mind–muscle connection to enhance muscle hypertrophy.

Influence of Maturation Status on Eccentric Exercise-Induced Muscle Damage and the Repeated Bout Effect in Females.

This study compared changes in indirect muscle damage markers, proprioception and arterial stiffness after elbow flexor eccentric exercise between pre-pubescent (9–10 y), pubescent (14–15 y), and post-pubescent (20–24 y) healthy, untrained females (n = 13/group). The maturation of the participants was confirmed by the hand bone age. All participants performed two bouts of 30 sub-maximal eccentric contractions (EC1, EC2) using a dumbbell set at 60% of pre-exercise maximal voluntary isometric elbow flexion strength at 90°. Changes in maximal voluntary concentric contraction (MVC) torque, muscle soreness (SOR), plasma creatine kinase activity, proprioception (position sense, joint reaction angle) and arterial stiffness (carotid-femoral pulse-wave velocity: cfPWV) before to 5 days after EC1 and EC2 were compared among groups by a mixed-design two-way ANOVA. Pre-exercise MVC torque and cfPWV were smaller (P < 0.05) for the pre-pubescent (MVC: 10.0 ± 0.9 Nm, cfPWV: 903 ± 60 cm/s) and the pubescent (14.3 ± 1.1 Nm, 967 ± 61 cm/s) than the post-pubescent (19.1 ± 1.4 Nm, 1,103 ± 73 cm/s). Changes in all variables after EC1 were smaller (P < 0.05) for the pre-pubescent (e.g., MVC at 1 d post-exercise: −10 ± 6%, peak SOR: 5 ± 2 mm) than the pubescent (−15 ± 9%, 12 ± 6 mm) and the post-pubescent (−25 ± 7%, 19 ± 13 mm). After EC2, changes in all variables were smaller (P < 0.05) than those after EC1 for all groups (e.g., MVC at 1 d post-exercise, pre-pubescent: −4 ± 6%, pubescent: −9 ± 4%, post-pubescent: −14 ± 5%; peak SOR: 3 ± 2, 7 ± 3, 11 ± 6 mm), but the magnitude of the repeated bout effect was not different (P > 0.05) among the groups. These results show that the extents of muscle damage, and proprioception and arterial stiffness changes after eccentric exercise are greater at later stages of maturation, but the repeated bout effect is not affected by maturation.

Elbow flexion and forearm supination strength in a healthy population

Despite the lack of representative data of a healthy population, many clinical trials concerning the measurement of postoperative elbow flexion or forearm supination strength use the contralateral side as a control. We hypothesized that there are no differences in elbow flexion and supination strength between the dominant and nondominant sides in healthy volunteers. The study was performed on a cross-sectional cohort of healthy subjects without any prior injuries or surgical interventions of the upper extremities. Isometric elbow flexion strength and supination strength were measured on both the dominant and nondominant sides. The results were analyzed for the entire group and subanalyzed for female vs. male, for different age groups, and according to handedness and regular practice of overhead sports. A total of 150 subjects (75 female and 75 male subjects; mean age, 44 ± 15 years [range, 18-72 years]) were included in this study. Within the entire collective, no significant differences concerning the elbow flexion strength between the dominant and nondominant sides could be detected, whereas the supination strength was 7% higher on the dominant side (P = .010). Women, right-hand-dominant subjects, and subjects who do not regularly practice overhead sports have a significant 8% higher supination strength on the dominant side compared with the nondominant side (P < .05). Left-hand-dominant subjects have an 8% higher elbow flexion strength on the nondominant right side (P < .05). Elbow flexion strength and forearm supination strength differ between the dominant and nondominant sides. The contralateral upper extremity cannot be used as a matched control without some adjustments.

The natural history of recovery of elbow flexion after obstetric brachial plexus injury managed without nerve repair.

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Twelve hours of a compression sleeve is not enough to improve the muscle recovery of an exercise-damaged upper arm

ObjectiveTo assess the efficacy of a compression sleeve worn for a short-time period (12h) on the recovery from the symptoms of exercise-induced upper arm muscle damage. MethodsA randomized controlled study was conducted on thirteen healthy young men using a standardized and exercise-induced upper arm muscle damage protocol, and they were immediately placed into two groups: TREATED (n=7) and CONTROL (n=6). Isometric elbow flexion strength, upper arm circumference, and muscle soreness measurements were taken before and at 24, 48, 72 and 96h after the damaging exercise, and were used as criteria of exercise-induced muscle damage. Group comparisons were made for each variable using a two-way ANOVA design (2 groups×5 measurements), and with a significance level of P<0.05. ResultsA significant impairment (P<0.001) was observed in muscle strength (∼43% and ∼34%, for CONTROL and TREATED groups, respectively, 24h after exercise), as well as a significant increase (P<0.001) in upper arm circumference (UAC) and muscle soreness (F4,55=6.49 for UAC and F4,55=6.95 for muscle soreness) among the measurements after exercise for both groups, with no significant differences between them. ConclusionsThese results, together with previous findings, suggest that the use of a compression garment for 12h is not enough to improve the recovery from exercise-induced muscle damage in the upper arm, and longer periods of compression may be necessary to achieve positive outcomes.

Anthropometrics and electromyography as predictors for maximal voluntary isometric arm strength

Abstract Background Muscular strength can be conceptually determined by two components: muscle activation and size. Muscle activation by the central nervous system can be measured by surface electromyography (sEMG). Muscular size reflects the amount of contractile protein within a skeletal muscle and can be estimated by anthropometric measurements. The purpose of this study was to determine the relative contributions of size parameters and muscle activation to the prediction of maximal voluntary isometric elbow flexion strength. Methods A series of anthropometric measurements were taken from 96 participants. Torque and root-mean-square (RMS) of the sEMG from the biceps brachii were averaged across three maximal voluntary isometric contractions. A multiple linear regression analysis was performed based on a Pearson's correlation matrix. Results Body weight (BW) accounted for 39.1% and 27.3% in males and females, respectively, and was the strongest predictor of strength for males. Forearm length (L3) was the strongest predictor of strength in females (partial R 2 = 0.391). Elbow circumference (ELB) accounted for a significant ( p Conclusion Anthropometrics provide a strong prediction equation for the estimation of isometric elbow flexion strength. Muscle activation, as measured by sEMG activity, accounted for a significant ( p

Comparison of low‐intensity blood flow‐restricted training‐induced muscular hypertrophy in eumenorrheic women in the follicular phase and luteal phase and age‐matched men

The purpose of this study was to compare the muscle hypertrophic response in women during both the follicular (FP) and the luteal phase (LP) of their menstrual cycles following short-term, low-intensity resistance training combined with blood flow restriction (BFR). Eight eumenorrheic women and five men, all previously untrained, performed unilateral low-intensity (30% of 1 repetition maximum) dumbbell curl training with BFR once a day for 6 days. The opposite arm served as an untrained control. This 6-day training programme was conducted during both menstrual cycle phases: the early FP and the mid LP. MRI-measured biceps muscle volume (MV) and isometric elbow flexion strength were measured in both arms before and 2 days after the final training bout. Significantly (P<0.05) greater muscle hypertrophy was observed in the LP (5·7%) than in the FP (3·7%). The absolute and relative changes in serum hormone concentrations between the two phases did not correlate (P>0.05) with the percentage change in MV between the LP and FP. There was no change in MV in the control arm for both cycle phases. Following training, isometric strength increased (P<0.01) in the LP, but not in the FP (P = 0.17). Relative strength (strength per unit MV) was similar pre- and post-training in both phases. The percentage changes in MV and strength were similar between the women (average of LP and FP) and men. Our results indicate that muscle hypertrophy and strength gain are higher in the LP than in the FP following 6 days of BFR training, although the sex difference in the training response is non-existent.

Comparison Of Muscle Hypertrophy During Follicular And Luteal Phases Following 6-days Blood-Flow Restricted Resistance Training

If anabolic/catabolic effects exist for female hormones, training-induced muscle hypertrophy might differ between follicular (low estrogen and progesterone) and luteal (elevated estrogen and progesterone) phases of the menstrual cycle. We reported previously that rapid significant increases in muscle mass occur following a short period (6 days, twice daily) of low-intensity resistance training combined with blood flow reduction (BFR). PURPOSE: To investigate the comparison of muscular hypertrophic responses between follicular and luteal phases of the menstrual cycle following low-intensity BFR resistance training. METHODS: Eight previously untrained, eumenorrheic women (age, 22-37 yrs; body weight, 52.9±4.8 kg; BMI, 21.3±1.6 kg/m2) performed unilateral low-intensity (30% of one-repetition maximal, 1-RM) dumbbell curl training (4 sets, 75 total contractions) combined with BFR once a day for 6 days. The opposite arm served as an untrained control throughout the training period. This 6-day training program was conducted during both menstrual cycle phases: early follicular (FP) and mid-luteal (LP). MRI-measured upper arm muscle volume and isometric elbow flexion strength were measured in both arms on before and two days after the final training bout. RESULTS: Serum concentrations of estrogen and progesterone were 57±40 pg/ml and 0.8±0.8 ng/ml, respectively, for FP and 198±113 pg/ml and 15.0±13.5 ng/ml for LP. Significantly (P<0.05) greater muscle hypertrophy was observed in the LP (biceps muscle volume; 5.7%) compared to the FP (3.7%). A significant positive correlation was observed between the training-induced increase in muscle volume and serum concentration of estrogen (r=0.66, P<0.05), but not with progesterone (r=0.27). There was no change in muscle volume in the control arm for both cycle phases. Increases in isometric elbow flexion strength were higher in the LP than that of the FP. Relative strength (isometric strength per unit muscle cross-sectional area) was similar between pre- and post-training in both phases. CONCLUSIONS: Our results suggest that female hormones may either exert an anabolic effect and/or a decreased catabolic effect during muscle hypertrophy and strength gains, although the independent effects of estrogen and progesterone were not evident.

Effects of sensory-level high-volt pulsed electrical current ondelayed-onset muscle soreness

Ten healthy males and ten healthy females aged 21.5 ± 3.2 years (mean ± s) participated in the study, which was designed to evaluate the effectiveness of sensory level-high volt pulsed electrical current (HVPC) on delayed-onset muscle soreness (DOMS). Arm discomfort, elbow extension range of motion and isometric elbow flexion strength were obtained as baseline measurements. Delayed-onset muscle soreness was induced in the participants' dominant or non-dominant arm using two sets of 20 maximal eccentric elbow flexion contractions. After the induction of DOMS, the participants were randomly divided into an experimental condition (HVPC) or a placebo condition. The experimental condition consisted of 20 min of HVPC immediately after the induction of DOMS, and 20 min every 24 h for three consecutive days thereafter. The participants in the placebo condition received an intervention similar in design; however, no electrical current was administered. Baseline measurements were reevaluated at 24, 48, 72 and 96 h after the induction of DOMS. Three weeks later, the participants returned and the protocol was repeated on the contralateral limb, using the opposite intervention (HVPC or placebo). Repeated-measures analysis of variance revealed a significant increase in overall arm discomfort, decrease in elbow extension and decrease in isometric strength for both conditions over time. No significant main effect of treatment, or time-by-treatment interaction, was found for the HVPC condition when compared with the placebo condition for any variable. Sensory-level HVPC, as utilized in our application, was ineffective in reducing the measured variables associated with DOMS.

Efficacy of a tart cherry juice blend in preventing the symptoms of muscle damage

Background: Numerous antioxidant and anti-inflammatory agents have been identified in tart cherries. Objective: To test the efficacy of a tart cherry juice blend in preventing the symptoms of exercise induced...

Training Distribution And The Acquisition Of Maximal Isometric Elbow Flexion Strength

PURPOSE This study compared massed versus distributed muscle contractions in the acquisition of maximal isometric elbow flexion strength, to understand the role of motor learning in resistive exercise. METHODS Twenty-six sedentary, collegeaged females were matched and randomly assigned to one of two groups. The massed group (n=13) completed 15 maximal isometric elbow flexion strength trials in one session, while the distributed group (n=13) performed five such contractions on three successive days. After a 2-week and 3 month rest interval, both groups returned to perform another five maximal isometric elbow flexion strength trials to assess retention of any potential strength gains. Elbow flexion torque and surface electromyography (SEMG) of the biceps and triceps were monitored concurrently. RESULTS There was a significant (P <0.05) increase in strength in both groups from Block 1 (first 5 contractions) to Block 2 (first retest) and from Block 1 to Block 3 (second retest). Both groups exhibited a an increase (P <0.05) in biceps root-mean-square (RMS) SEMG amplitude. A significant (P <0.05) decrease in triceps RMS SEMG amplitude was found between Block 1 and Block 2 for both groups. However, a significant (P <0.05) increase was found between Block 2 and 3. CONCLUSIONS These results suggest that there is flexibility in resistive exercise schedules. There was a continued increase in neural drive to the agonist muscle throughout testing. This was accompanied by a reduction in antagonist coactivation that was a short-term (2-weeks) training effect, dissipated over the longer rest interval (3-months).

Training Distribution And The Acquisition Of Maximal Isometric Elbow Flexion Strength

PURPOSE This study compared massed versus distributed muscle contractions in the acquisition of maximal isometric elbow flexion strength, to understand the role of motor learning in resistive exercise. METHODS Twenty-six sedentary, collegeaged females were matched and randomly assigned to one of two groups. The massed group (n=13) completed 15 maximal isometric elbow flexion strength trials in one session, while the distributed group (n=13) performed five such contractions on three successive days. After a 2-week and 3 month rest interval, both groups returned to perform another five maximal isometric elbow flexion strength trials to assess retention of any potential strength gains. Elbow flexion torque and surface electromyography (SEMG) of the biceps and triceps were monitored concurrently. RESULTS There was a significant (P <0.05) increase in strength in both groups from Block 1 (first 5 contractions) to Block 2 (first retest) and from Block 1 to Block 3 (second retest). Both groups exhibited a an increase (P <0.05) in biceps root-mean-square (RMS) SEMG amplitude. A significant (P <0.05) decrease in triceps RMS SEMG amplitude was found between Block 1 and Block 2 for both groups. However, a significant (P <0.05) increase was found between Block 2 and 3. CONCLUSIONS These results suggest that there is flexibility in resistive exercise schedules. There was a continued increase in neural drive to the agonist muscle throughout testing. This was accompanied by a reduction in antagonist coactivation that was a short-term (2-weeks) training effect, dissipated over the longer rest interval (3-months).

Limitations of Wrist Strength to Manual Exertion Capability in 2D Biomechanical Modeling

The objective of this study is to evaluate the assumption in biomechanical models that wrist strength does not limit manual exertion capability. An experiment was designed and run on right-handed males to test isometric elbow flexion strength at two included elbow angles: 90° and 135° and in two forearm positions: supinated and mid between supination and pronation. Isometric wrist flexion strength was also measured at the same elbow angles and at two wrist positions in the flexion/extension plane: neutral and 45° extended. Isometric wrist radial deviation strength was measured at the same two elbow angles and at two wrist positions in the radial/ulnar deviation plane: neutral and 30° ulnarly deviated. An equation was developed to calculate the theoretical minimum wrist strength limits for which wrist strength does not limit maximal moments about the elbow. These calculated limits were compared to the corresponding measured wrist strength moments. In general, wrist strength was found to be non-limiting, but in some specific circumstances, it can be limiting. Among the posture/exertion combinations tested, only wrist flexion strength in the extended wrist posture was found to be limiting. There was some evidence that strong-wrist people show less wrist strength limitations than weak-wrist people in some postures. It was also found that the neutral wrist posture is not associated with the highest wrist strength.

Characteristics of muscle activities in a quick change in magnitude of force.

The present study was designed to examine the characteristics of muscle activities in a quick voluntary change in magnitude of force. 15 subjects were asked to change their magnitude of force from 50% of maximal isometric elbow-flexion strength (MVS) to 20% MVS as quickly as possible. On each EMG of biceps and triceps, a period with no muscle activity was observed. It seems that the occurrence of the pause in muscle activity on EMG contributes to more quick change in magnitude of exerted force.

The Use of Analysis of Variance in Estimating Reliability of Isometric Elbow Flexion Strength

Abstract Thirty-six male college students served as subjects in a study to determine the reliability of isometric strength assessment of the right elbow flexor muscles by means of an intraclass correlation technique and to estimate reliability one might obtain under similar conditions with different combinations of days and trials. An analysis of variance treatment by subjects design was used to obtain the estimates of error necessary for calculation of the estimate of reliability. Some consideration was given to the effect of degrees of freedom on negative estimates of variance.