scholarly journals Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass

2019 ◽  
Author(s):  
Omar Baritello ◽  
Mina Khajooei ◽  
Tilman Engel ◽  
Stephan Kopinski ◽  
Andrew Quarmby ◽  
...  
Keyword(s):  
Muscle Activation ◽  
External Rotation ◽  
Muscular Activity ◽  
Shoulder Injury ◽  
Serratus Anterior ◽  
Maximal Voluntary Isometric Contraction ◽  
Cross Sectional ◽  
Neuromuscular Activity ◽  
Custom Made ◽  
Flexion Extension

Abstract Background Recent shoulder injury prevention programs have utilized resistance exercises combined with different forms of instability, with the goal of eliciting functional adaptations and thereby reducing the risk of injury. However, it is still unknown how an unstable weight mass affects the muscular activity of the shoulder stabilizers (ST). Aim of the study was to analyzed the neuromuscular activity of the dynamic ST under four combinations of stable and unstable weight mass during three shoulder exercises. It was hypothesized that a combined condition of weight with unstable mass would elicit significantly greater activation due to the increased stabilization demand. Methods Sixteen participants (7 m/9 f) were included in this cross-sectional study and prepared with an EMG-setup for the: Mm. upper/lower trapezius (U.TA/L.TA), lateral deltoid (DE), latissimus dorsi (LD), serratus anterior (SA) and pectoralis major (PE). A maximal voluntary isometric contraction test (MVIC; 5 sec.) was performed on an isokinetic dynamometer. Next, internal/external rotation (In/Ex), abduction/adduction (Ab/Ad) and diagonal flexion/extension (F/E) exercises (5 reps.) were performed with four custom-made-pipes representing different training conditions. First, the empty-pipe (P; 0.5 kg) and then, randomly ordered, water-filled-pipe (PW; 1 kg), weight-pipe (PG; 4.5 kg) and weight + water-filled-pipe (PWG; 4.5 kg), while EMG was recorded. Raw root mean square values (RMS) were normalized to MVIC (%MVIC). Differences between conditions for RMS%MVIC, scapular stabilizer (SR: U.TA/L.TA; U.TA/SA) and contraction (CR: concentric/eccentric) ratios were analyzed (paired t-test;Bonferroni adjusted α=0.008) Results PWG showed significantly greater activation for all exercises and all muscles except for PE compared to P and PW. Condition PG elicited muscular activity comparable to PWG (p>0.008) with significantly lower activation of L.TA and SA in the In/Ex rotation. The SR ratio was significantly higher in PWG compared to P and PW. No significant differences were found for the CR ratio in all exercises and for all muscles. Conclusion Higher weight generated greater muscle activation whereas an unstable weight mass behavior raised the neuromuscular activity, increasing the stabilization demands. Especially in the In/Ex rotation, an unstable weight mass increased the RMS%MVIC and SR ratio. This might improve training effects in shoulder prevention and rehabilitation programs.

scholarly journals Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass

2019 ◽  
Author(s):  
Omar Baritello ◽  
Mina Khajooei ◽  
Tilman Engel ◽  
Stephan Kopinski ◽  
Andrew Quarmby ◽  
...  
Keyword(s):  
Muscle Activation ◽  
External Rotation ◽  
Muscular Activity ◽  
Shoulder Injury ◽  
Serratus Anterior ◽  
Maximal Voluntary Isometric Contraction ◽  
Cross Sectional ◽  
Neuromuscular Activity ◽  
Custom Made ◽  
Flexion Extension

Abstract Background:Recent shoulder injury prevention programs have utilized resistance exercises combined with different forms of instability, with the goal of eliciting functional adaptations and thereby reducing the risk of injury. However, it is still unknown how an unstable weight mass (UWM) affects the muscular activity of the shoulder stabilizers. Aim of the study was to assess neuromuscular activity of dynamic shoulder stabilizers under four conditions of stable and UWM during three shoulder exercises. It was hypothesized that a combined condition of weight with UWM would elicit greater activation due to the increased stabilization demand. Methods:Sixteen participants (7 m/9 f) were included in this cross-sectional study and prepared with an EMG-setup for the: Mm. upper/lower trapezius (U.TA/L.TA), lateral deltoid (DE), latissimus dorsi (LD), serratus anterior (SA) and pectoralis major (PE). A maximal voluntary isometric contraction test (MVIC; 5 sec.) was performed on an isokinetic dynamometer. Next, internal/external rotation (In/Ex), abduction/adduction (Ab/Ad) and diagonal flexion/extension (F/E) exercises (5 reps.) were performed with four custom-made-pipes representing different training conditions. First, the empty-pipe (P; 0.5 kg) and then, randomly ordered, water-filled-pipe (PW; 1 kg), weight-pipe (PG; 4.5 kg) and weight + water-filled-pipe (PWG; 4.5 kg), while EMG was recorded. Raw root mean square values (RMS) were normalized to MVIC (%MVIC). Differences between conditions for RMS%MVIC, scapular stabilizer (SR : U.TA/L.TA; U.TA/SA) and contraction (CR : concentric/eccentric) ratios were analyzed (paired t-test; a = 0.05; Bonferroni adjusted a = 0.008). Results:PWG showed significantly greater muscle activity for all exercises and all muscles except for PE compared to P and PW. Condition PG elicited muscular activity comparable to PWG (p> 0.008) with significantly lower activation of L.TA and SA in the In/Ex rotation. The SR ratio was significantly higher in PWG compared to P and PW. No significant differences were found for the CR ratio in all exercises and for all muscles. Conclusion:Higher weight generated greater muscle activation whereas an UWM raised the neuromuscular activity, increasing the stabilization demands. Especially in the In/Ex rotation, an unstable weight mass increased the RMS%MVIC and SR ratio. This might improve training effects in shoulder prevention and rehabilitation programs.

scholarly journals Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass

2019 ◽  
Author(s):  
Omar Baritello ◽  
Mina Khajooei ◽  
Tilman Engel ◽  
Stephan Kopinski ◽  
Andrew Quarmby ◽  
...  
Keyword(s):  
Muscle Activation ◽  
External Rotation ◽  
Muscular Activity ◽  
Shoulder Injury ◽  
Serratus Anterior ◽  
Maximal Voluntary Isometric Contraction ◽  
Cross Sectional ◽  
Neuromuscular Activity ◽  
Custom Made ◽  
Flexion Extension

Abstract Background Recent shoulder injury prevention programs have utilized resistance exercises combined with different forms of instability, with the goal of eliciting functional adaptations and thereby reducing the risk of injury. However, it is still unknown how an unstable weight mass affects the muscular activity of the shoulder stabilizers. Aim of the study was to analyzed the neuromuscular activity of the dynamic shoulder stabilizers under four combinations of stable and unstable weight mass during three shoulder exercises. It was hypothesized that a combined condition of weight with unstable mass would elicit significantly greater activation due to the increased stabilization demand. Methods Sixteen participants (7 m/9 f) were included in this cross-sectional study and prepared with an EMG-setup for the: Mm. upper/lower trapezius (U.TA/L.TA), lateral deltoid (DE), latissimus dorsi (LD), serratus anterior (SA) and pectoralis major (PE). A maximal voluntary isometric contraction test (MVIC; 5 sec.) was performed on an isokinetic dynamometer. Next, internal/external rotation (In/Ex), abduction/adduction (Ab/Ad) and diagonal flexion/extension (F/E) exercises (5 reps.) were performed with four custom-made-pipes representing different training conditions. First, the empty-pipe (P; 0.5 kg) and then, randomly ordered, water-filled-pipe (PW; 1 kg), weight-pipe (PG; 4.5 kg) and weight + water-filled-pipe (PWG; 4.5 kg), while EMG was recorded. Raw root mean square values (RMS) were normalized to MVIC (%MVIC). Differences between conditions for RMS%MVIC, scapular stabilizer (SR: U.TA/L.TA; U.TA/SA) and contraction (CR: concentric/eccentric) ratios were analyzed (paired t-test; α=0.05; Bonferroni adjusted α=0.008) Results PWG showed significantly greater muscle activity for all exercises and all muscles except for PE compared to P and PW. Condition PG elicited muscular activity comparable to PWG (p>0.008) with significantly lower activation of L.TA and SA in the In/Ex rotation. The SR ratio was significantly higher in PWG compared to P and PW. No significant differences were found for the CR ratio in all exercises and for all muscles. Conclusion Higher weight generated greater muscle activation whereas an unstable weight mass behavior raised the neuromuscular activity, possibly due to increased stabilization demands. Application of an unstable weight mass may be beneficial to improve training effects in shoulder prevention and rehabilitation programs.

scholarly journals Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass.

2020 ◽  
Author(s):  
Omar Baritello ◽  
Mina Khajooei ◽  
Tilman Engel ◽  
Stephan Kopinski ◽  
Andrew Quarmby ◽  
...  
Keyword(s):  
Muscle Activation ◽  
External Rotation ◽  
Muscular Activity ◽  
Shoulder Injury ◽  
Serratus Anterior ◽  
Maximal Voluntary Isometric Contraction ◽  
Cross Sectional ◽  
Neuromuscular Activity ◽  
Custom Made ◽  
Flexion Extension

Abstract Background:Recent shoulder injury prevention programs have utilized resistance exercises combined with different forms of instability, with the goal of eliciting functional adaptations and thereby reducing the risk of injury. However, it is still unknown how an unstable weight mass affects the muscular activity of the shoulder stabilizers.Aim of the study was to analyze the neuromuscular activity of the dynamic shoulder stabilizers under four conditions of stable and unstable weight mass during three shoulder exercises. It was hypothesized that a combined condition of weight with unstable mass would elicit significantly greater activation due to the increased stabilization demand.MethodsSixteen participants (7 m/9 f) were included in this cross-sectional study and prepared with an EMG-setup for the: Mm. upper/lower trapezius (U.TA/L.TA), lateral deltoid (DE), latissimus dorsi (LD), serratus anterior (SA) and pectoralis major (PE). A maximal voluntary isometric contraction test (MVIC; 5 sec.) was performed on an isokinetic dynamometer. Next, internal/external rotation (In/Ex), abduction/adduction (Ab/Ad) and diagonal flexion/extension (F/E) exercises (5 reps.) were performed with four custom-made-pipes representing different training conditions. First, the empty-pipe (P; 0.5 kg) and then, randomly ordered, water-filled-pipe (PW; 1 kg), weight-pipe (PG; 4.5 kg) and weight + water-filled-pipe (PWG; 4.5 kg), while EMG was recorded. Raw root mean square values (RMS) were normalized to MVIC (%MVIC). Differences between conditions for RMS%MVIC, scapular stabilizer (SR: U.TA/L.TA; U.TA/SA) and contraction (CR: concentric/eccentric) ratios were analyzed (paired t-test; a = 0.05; Bonferroni adjusted a = 0.008) ResultsPWG showed significantly greater muscle activity for all exercises and all muscles except for PE compared to P and PW. Condition PG elicited muscular activity comparable to PWG (p > 0.008) with significantly lower activation of L.TA and SA in the In/Ex rotation. The SR ratio was significantly higher in PWG compared to P and PW. No significant differences were found for the CR ratio in all exercises and for all muscles.ConclusionHigher weight generated greater muscle activation whereas an unstable weight mass behavior raised the neuromuscular activity, increasing the stabilization demands. Especially in the In/Ex rotation, an unstable weight mass increased the RMS%MVIC and SR ratio. This might improve training effects in shoulder prevention and rehabilitation programs.Trial Registration: not applicable

scholarly journals Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass.

2020 ◽  
Author(s):  
Omar Baritello ◽  
Mina Khajooei ◽  
Tilman Engel ◽  
Stephan Kopinski ◽  
Andrew Quarmby ◽  
...  
Keyword(s):  
Muscle Activation ◽  
External Rotation ◽  
Muscular Activity ◽  
Shoulder Injury ◽  
Serratus Anterior ◽  
Maximal Voluntary Isometric Contraction ◽  
Cross Sectional ◽  
Neuromuscular Activity ◽  
Custom Made ◽  
Flexion Extension

Abstract Background: Recent shoulder injury prevention programs have utilized resistance exercises combined with different forms of instability, with the goal of eliciting functional adaptations and thereby reducing the risk of injury. However, it is still unknown how an unstable weight mass (UWM) affects the muscular activity of the shoulder stabilizers. Aim of the study was to assess neuromuscular activity of dynamic shoulder stabilizers under four conditions of stable and UWM during three shoulder exercises. It was hypothesized that a combined condition of weight with UWM would elicit greater activation due to the increased stabilization demand. Methods: Sixteen participants (7 m/9 f) were included in this cross-sectional study and prepared with an EMG-setup for the: Mm. upper/lower trapezius (U.TA/L.TA), lateral deltoid (DE), latissimus dorsi (LD), serratus anterior (SA) and pectoralis major (PE). A maximal voluntary isometric contraction test (MVIC; 5 sec.) was performed on an isokinetic dynamometer. Next, internal/external rotation (In/Ex), abduction/adduction (Ab/Ad) and diagonal flexion/extension (F/E) exercises (5 reps.) were performed with four custom-made-pipes representing different exercise conditions. First, the empty-pipe (P; 0.5 kg) and then, randomly ordered, water-filled-pipe (PW; 1 kg), weight-pipe (PG; 4.5 kg) and weight + water-filled-pipe (PWG; 4.5 kg), while EMG was recorded. Raw root-mean-square values (RMS) were normalized to MVIC (%MVIC). Differences between conditions for RMS%MVIC, scapular stabilizer (SR: U.TA/L.TA; U.TA/SA) and contraction (CR: concentric/eccentric) ratios were analyzed (paired t-test; p ≤ 0.05; Bonferroni adjusted α = 0.008). Results: PWG showed significantly greater muscle activity for all exercises and all muscles except for PE compared to P and PW. Condition PG elicited muscular activity comparable to PWG (p > 0.008) with significantly lower activation of L.TA and SA in the In/Ex rotation. The SR ratio was significantly higher in PWG compared to P and PW. No significant differences were found for the CR ratio in all exercises and for all muscles. Conclusion: Higher weight generated greater muscle activation whereas an UWM raised the neuromuscular activity, increasing the stabilization demands. Especially in the In/Ex rotation, an UWM increased the RMS%MVIC and SR ratio. This might improve training effects in shoulder prevention and rehabilitation programs.Trial Registration: not applicable

Rehabilitation Exercises for Dysfunction of the Scapula: Exploration of Muscle Activity Using Fine-Wire EMG

2021 ◽  
pp. 036354652110250
Author(s):  
Kelly R. Berckmans ◽  
Birgit Castelein ◽  
Dorien Borms ◽  
Thierry Parlevliet ◽  
Ann Cools
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Clinical Decision Making ◽  
External Rotation ◽  
Clinical Decision ◽  
Moderate Activity ◽  
Serratus Anterior ◽  
Maximal Voluntary Isometric Contraction ◽  
Forward Flexion ◽  
Muscle Balance

Background: Scapular muscle activity during shoulder exercises has been explored with surface electromyography (EMG). However, knowledge about the activity of deeper-layer scapular muscles is still limited. Purpose: To investigate EMG activation of the deeper-layer scapular stabilizers (levator scapulae [LS], rhomboid major [RM], pectoralis minor [Pm] muscles) together with superficial muscle activity (upper [UT], middle [MT], and lower trapezius [LT] and serratus anterior [SA]) during 4 exercises often used for training scapular function. Based on the amplitude EMG of the deeper-layer muscles, scapular muscle activation ratios for the 4 exercises were calculated, hereby providing knowledge of the optimal muscle balance. Study Design: Descriptive laboratory study. Methods: A total of 26 healthy participants performed 4 shoulder exercises (side-lying external rotation [ER], side-lying forward flexion, prone horizontal abduction with ER, and prone extension) while simultaneously measuring scapular muscle activity. Intramuscular electrodes were used for the deeper layer, in contrast to surface electrodes for the superficial muscles. All data were normalized to percentage of maximal voluntary isometric contraction (%MVIC), and the activation ratios (the muscle activity of the deeper layer relative to the other muscles) were calculated. A 1-way analysis of variance with Bonferroni correction was applied for statistical analysis. Results: Moderate activity was found in all exercises for the LS and RM (25%-45% MVIC). The Pm resulted in low activity during both side-lying exercises (13%-18% MVIC). Ratios involving LS or RM showed values >1 for all exercises (1.28-12.41) except for LS/MT, LS/LT, and LS/RM (0.85-0.98) during side-lying ER, and LS/MT, RM/MT and RM/LS (0.85-0.99) during side-lying forward flexion. Likewise, values <1 were found when MT (0.85) and LS (0.99) were involved with RM in the numerator during side-lying forward flexion. Ratios with Pm in the numerator showed values <1, apart from the ratios with UT and SA in the denominator. Conclusion: The study provides extended knowledge about the deeper-layer scapular muscle activity and related ratios during the 4 shoulder exercises mentioned here. Putting theory into practice, based on our results, we advise both side-lying exercises to be performed to strengthen LT and MT, even in case of hyperactivity of the Pm. However, the 4 exercises should be given carefully to patients with hyperactivity in the LS and/or RM. Clinical Relevance: The findings of this study may assist clinical decision making in exercise selection for restoring scapular function.

scholarly journals Age-Related, Sport-Specific Adaptions of the Shoulder Girdle in Elite Adolescent Tennis Players

2014 ◽  
Vol 49 (5) ◽  
pp. 647-653 ◽  
Author(s):  
Ann M. Cools ◽  
Tanneke Palmans ◽  
Fredrik R. Johansson
Keyword(s):  
Muscle Strength ◽  
Shoulder Girdle ◽  
Vital Role ◽  
The Body ◽  
Injury Incidence ◽  
Shoulder Injury ◽  
Serratus Anterior ◽  
Cross Sectional ◽  
Tennis Players ◽  
Age Related

Context Tennis requires repetitive overhead movements that can lead to upper extremity injury. The scapula and the shoulder play a vital role in injury-free playing. Scapular dysfunction and glenohumeral changes in strength and range of motion (ROM) have been associated with shoulder injury in the overhead athlete. Objective To compare scapular position and strength and shoulder ROM and strength between Swedish elite tennis players of 3 age categories (&lt;14, 14–16, and &gt;16 years). Design Cross-sectional study. Setting Tennis training sports facilities. Patients or Other Participants Fifty-nine adolescent Swedish elite tennis players (ages 10–20 years) selected based on their national ranking. Main Outcome Measure(s) We used a clinical screening protocol with a digital inclinometer and a handheld dynamometer to measure scapular upward rotation at several angles of arm elevation, isometric scapular muscle strength, glenohumeral ROM, and isometric rotator cuff strength. Results Players older than 16 years showed less scapular upward rotation on the dominant side at 90° and 180° (P &lt; .05). Although all absolute scapular muscle strength values increased with age, there was no change in the body-weight–normalized strength of the middle (P = .9) and lower (P = .81) trapezius or serratus anterior (P = .17). Glenohumeral internal-rotation ROM and total ROM tended to decrease, but this finding was not statistically significant (P = .052 and P = .06, respectively). Whereas normalized internal-rotator strength increased from 14 to 16 years to older than 16 years (P = .009), normalized external-rotator and supraspinatus strength remained unchanged. Conclusions Age-related changes in shoulder and scapular strength and ROM were apparent in elite adolescent tennis players. Future authors should examine the association of these adaptations with performance data and injury incidence.

Flexibility, Position, and Strength of the Shoulder Complex in Pediatric and Adult Amateur Tennis Athletes

2021 ◽  
pp. 1-9
Author(s):  
Germanna M. Barbosa ◽  
Larissa P. Ribeiro ◽  
Ana B. Nasser ◽  
Gretchen D. Oliver ◽  
Paula R. Camargo
Keyword(s):  
At Risk ◽  
Outcome Measures ◽  
External Rotation ◽  
Posterior Capsule ◽  
Serratus Anterior ◽  
Cross Sectional ◽  
Shoulder Range Of Motion ◽  
Cutoff Values ◽  
Shoulder Complex ◽  
Dominant Side

Context: Understanding the musculoskeletal adaptations in the shoulder complex of varying ages of tennis athletes may suggest preventive protocols and conditioning and rehabilitation programs to this population. This study aimed to generate a bilateral descriptive profile of shoulder flexibility, scapular and clavicular position, and muscle strength in pediatric and adult amateur tennis athletes. The outcome measures were compared between groups and sides. The number and percentage of athletes “at risk” according to cutoff values for shoulder range of motion (ROM) were also analyzed. Design: Cross-sectional study. Methods: 36 pediatric and 28 adult amateur tennis athletes were tested. Outcome measures were ROM of shoulder flexion, abduction, internal and external rotation, posterior capsule tightness, pectoralis minor index (PMI), scapular upward rotation, clavicular elevation, and strength of the external rotators, serratus anterior, and lower trapezius of the dominant/nondominant sides. Results: Pediatric athletes had greater dominant side external rotation (P = .01) and total ROM (P = .04), increased Low Flexion test (P = .01), and decreased PMI (P = .01) compared with the adults. Bilaterally, the pediatric athletes had greater dominant side external rotation ROM (P < .01) and decreased PMI (P = .002) as compared with their nondominant side, whereas the adults displayed lower values on posterior capsule tightness (P = .01) and decreased PMI (P = .02) on their dominant side compared with their nondominant side. For the remaining outcomes, no interaction effects were observed. The cutoff values for shoulder ROM showed that several athletes were “at risk” of shoulder problems. Conclusion: Upper extremity adaptations at the shoulder are present in both pediatric and adult tennis athletes. These data can assist clinicians in better understanding the biomechanical adaptations in the shoulder of amateur tennis athletes in different age groups.

scholarly journals Effect of Pitching Consecutive Days in Youth Fast-Pitch Softball Tournaments on Objective Shoulder Strength and Subjective Shoulder Symptoms

2017 ◽  
Vol 45 (6) ◽  
pp. 1413-1419 ◽  
Author(s):  
S. Andrew Skillington ◽  
Robert H. Brophy ◽  
Rick W. Wright ◽  
Matthew V. Smith
Keyword(s):  
Shoulder Pain ◽  
External Rotation ◽  
Elbow Flexion ◽  
Strength Loss ◽  
Complete Recovery ◽  
Progressive Increase ◽  
Shoulder Abduction ◽  
Shoulder Injury ◽  
Level Of Evidence ◽  
Cross Sectional

Background: The windmill pitching motion has been associated with risk for shoulder injury. Because there are no pitching limits on youth fast-pitch softball pitchers, these athletes often pitch multiple games across consecutive days. Strength changes, fatigue levels, and shoulder pain that develop among female fast-pitch pitchers over the course of consecutive days of pitching have not been investigated. Hypothesis: Over the course of 2- and 3-day fast-pitch softball tournaments, pitchers will develop progressive objective weakness and increased subjective shoulder fatigue and pain without complete recovery between days. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Fourteen female fast-pitch softball pitchers between the ages of 14 and 18 years were evaluated for strength and fatigue changes across 2- and 3-day tournaments. At the beginning and end of each day of tournament play, pitchers were asked to quantify shoulder fatigue and shoulder pain levels of their dominant throwing arm using a 10-point visual analog scale (VAS). Shoulder abduction, flexion, external rotation, internal rotation, elbow flexion, and elbow extension strength measurements were gathered using a handheld dynamometer. Results: Over the course of an average single day of tournament participation, pitchers developed significant increases in VAS scores for shoulder fatigue (median, 2.0; 95% CI, 1.3-3.0) and pain (median, 1.3; 95% CI, 0.5-2.3) and significant strength loss in all tested motions. Pitchers also developed significant increases in VAS shoulder fatigue (median, 3.5; 95% CI, 1.5-5.5), VAS shoulder pain (median, 2.5; 95% CI, 1.0-4.5), and strength loss in all tested motions over the entire tournament. Shoulder pain, fatigue, and strength do not fully recover between days. The accumulation of subjective shoulder pain and fatigue over the course of tournament play were closely correlated. Conclusion: Among youth female fast-pitch softball pitchers, there is a progressive increase in shoulder fatigue, pain, and weakness over the course of 2- and 3-day tournaments without full recovery between consecutive days of pitching.

scholarly journals Shoulder External Rotation Fatigue and Scapular Muscle Activation and Kinematics in Overhead Athletes

2011 ◽  
Vol 46 (4) ◽  
pp. 349-357 ◽  
Author(s):  
Mithun Joshi ◽  
Charles A. Thigpen ◽  
Kevin Bunn ◽  
Spero G. Karas ◽  
Darin A. Padua
Keyword(s):  
Muscle Fatigue ◽  
Muscle Activation ◽  
External Rotation ◽  
Shoulder Injuries ◽  
Serratus Anterior ◽  
Overhead Athletes ◽  
Scapular Kinematics ◽  
Fatigue Protocol ◽  
Upper Trapezius ◽  
Lower Trapezius

Context: Glenohumeral external rotation (GH ER) muscle fatigue might contribute to shoulder injuries in overhead athletes. Few researchers have examined the effect of such fatigue on scapular kinematics and muscle activation during a functional movement pattern. Objective: To examine the effects of GH ER muscle fatigue on upper trapezius, lower trapezius, serratus anterior, and infraspinatus muscle activation and to examine scapular kinematics during a diagonal movement task in overhead athletes. Setting: Human performance research laboratory. Design: Descriptive laboratory study. Patients or Other Participants: Our study included 25 overhead athletes (15 men, 10 women; age = 20 ± 2 years, height = 180 ± 11 cm, mass = 80 ± 11 kg) without a history of shoulder pain on the dominant side. Intervention(s): We tested the healthy, dominant shoulder through a diagonal movement task before and after a fatiguing exercise involving low-resistance, high-repetition, prone GH ER from 0° to 75° with the shoulder in 90° of abduction. Main Outcome Measure(s): Surface electromyography was used to measure muscle activity for the upper trapezius, lower trapezius, serratus anterior, and infraspinatus. An electromyographic motion analysis system was used to assess 3-dimensional scapular kinematics. Repeated-measures analyses of variance (phase × condition) were used to test for differences. Results: We found a decrease in ascending-phase and descending-phase lower trapezius activity (F1,25 = 5.098, P = .03) and an increase in descending-phase infraspinatus activity (F1,25 = 5.534, P = .03) after the fatigue protocol. We also found an increase in scapular upward rotation (F1,24 = 3.7, P = .04) postfatigue. Conclusions: The GH ER muscle fatigue protocol used in this study caused decreased lower trapezius and increased infraspinatus activation concurrent with increased scapular upward rotation range of motion during the functional task. This highlights the interdependence of scapular and glenohumeral force couples. Fatigue-induced alterations in the lower trapezius might predispose the infraspinatus to injury through chronically increased activation.

scholarly journals Relationships between Hip Flexibility and Pitching Biomechanics in Adolescent Baseball Pitchers

2021 ◽  
Author(s):  
Maxwell L. Albiero ◽  
Wesley Kokott ◽  
Cody Dziuk ◽  
Janelle A. Cross
Keyword(s):  
External Rotation ◽  
Pearson Correlation ◽  
Three Dimensional ◽  
Correlation Coefficients ◽  
Kinematic Chain ◽  
Abduction Angle ◽  
Cross Sectional ◽  
Flexion Extension ◽  
Hip Abduction ◽  
Baseball Pitchers

Abstract Context: Inadequate hip active range of motion (AROM) may stifle the energy flow through the kinematic chain and decrease pitching performance while increasing the risk for pitcher injury. Objective: To examine the relationship of hip AROM and pitching biomechanics during a fastball pitch in adolescent baseball pitchers. Design: Cross-Sectional study. Setting: Biomechanics laboratory. Participants: A voluntary sample of 21 adolescent baseball pitchers (16.1 ± 0.8 yrs.; 183.9 ± 5.2 cm; 77.9 ± 8.3 kg). Main Outcome Measure (s): Bilateral hip internal rotation (IR), external rotation (ER), flexion, extension, and abduction AROM were measured. Three-dimensional biomechanics were assessed as participants threw from an indoor pitching mound to a strike zone net at regulation distance. Pearson correlation coefficients were used to determine correlations between hip AROM and biomechanical metrics. Results: Statistically significant negative correlations were found at foot contact between back hip ER AROM and back hip abduction angle (p=0.030, r=−0.474), back hip ER AROM and torso rotation angle (p=0.032, r=−0.468),and back hip abduction AROM and lead hip abduction angle (p=0.037, r=−0.458). Back hip extension AROM was positively correlated with increased stride length (p=0.043, r=0.446). Lead hip abduction AROM was also positively correlated with normalized elbow varus torque (p=0.034, r=0.464). Conclusions: There were several relationships between hip AROM and biomechanical variables during the pitching motion. The findings support the influence hip AROM can have on pitching biomechanics. Overall, greater movement at the hips allows for the kinematic chain to work at its maximal efficiency, increasing pitch velocity potential.

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