scholarly journals Auditory biofeedback decreases jump performance in figure skaters

2014 ◽  
Vol 8 (1) ◽  
Author(s):  
Joao A. C. Barros ◽  
Llanel Florendo ◽  
Yvonne Le
Keyword(s):  
Repeated Measures ◽  
Knee Flexion ◽  
Critical Factor ◽  
Cycling Performance ◽  
Emg Activity ◽  
Jump Height ◽  
Jump Performance ◽  
Figure Skaters ◽  
Female Adolescence ◽  
Do So

The few studies that attempted to increase jump height in figure skaters (Haguenauer et al., 2005, Law & Ste-Marie, 2005) have failed to do so. These studies did not focus on increasing knee flexion, a critical factor for jump height (Moran & Wallace, 2007, Vanezis & Lees, 2005). Auditory biofeedback has been shown to modify posture, balance and cycling performance (Dozza et al., 2011; Nicolai et al., 2010; Liu & Jensen, 2009) and could potentially be used to increase knee flexion in figure skaters. To investigate the effects of auditory biofeedback on the performance of Lutz jumps. Thirteen intermediate level female adolescence figure skaters performed 6 off-ice Lutz jumps under each of 2 conditions: 1) WITH auditory biofeedback; 2) and WITHOUT auditory biofeedback. Auditory biofeedback was provided via EMG Retrainer. Separate repeated measures ANOVAs were conducted for time in the air, knee flexion and EMG activity. Differences between conditions for time in the air (p = .012) and knee flexion (p = .049) were identified. Auditory biofeedback increased knee flexion and decreased jump height. In this case, auditory biofeedback might have directed performers attention to an internal cue disrupting performance (Wulf, 2007).

Roller Massage Prior to Running Does Not Affect Gait Mechanics in Well-Trained Runners

2021 ◽  
pp. 1-9
Author(s):  
Jessica G. Hunter ◽  
Gina L. Garcia ◽  
Sushant M. Ranadive ◽  
Jae Kun Shim ◽  
Ross H. Miller
Keyword(s):  
Repeated Measures ◽  
Reaction Force ◽  
Force Production ◽  
Endurance Athletes ◽  
Jump Height ◽  
Jump Performance ◽  
Average Load ◽  
Load Rate ◽  
Free Moment ◽  
Muscle Force Production

Context: Understanding if roller massage prior to a run can mitigate fatigue-related decrements in muscle force production during prolonged running is important because of the association between fatigue and running-related injury. Objective: The authors investigated whether a bout of roller massage prior to running would (1) mitigate fatigue-related increases in vertical average load rate and free moment of the ground reaction force of running and (2) mitigate decreases in maximal countermovement jump height. Design: Repeated-measures study. Setting: Laboratory. Participants: A total of 14 recreational endurance athletes (11 men and 3 women) volunteered for the study. Interventions: A 12.5-minute foam roller protocol for the lower extremities and a fatiguing 30-minute treadmill run. Main Outcome Measures: Vertical average load rate, free moment, and maximal jump height before (PRE) and after (POST) the fatiguing treadmill run on separate experimental days: once where participants sat quietly prior to the fatiguing run (REST) and another where the foam roller protocol was performed prior to the run (ROLL). Results: A 2-way multiple analysis of variance found no significant differences in vertical average load rate, free moment, and jump height between PRE/POST times in both REST/ROLL conditions. Conclusions: The authors concluded that recreational endurance athletes maintain running mechanics and jump performance after a fatiguing run regardless of prerun roller massage and may not rely on prerun roller massage as a form of injury prevention.

Using an overhead target increases volleyball-specific vertical jump performance

2021 ◽  
pp. 175433712110396
Author(s):  
Mehmet Yildiz ◽  
Zeki Akyildiz ◽  
Filipe Manuel Clemente ◽  
Deniz Yildiz
Keyword(s):  
Training Program ◽  
Repeated Measures ◽  
Vertical Jump ◽  
Control Group ◽  
Jump Height ◽  
Long Term Effects ◽  
Jump Performance ◽  
Volleyball Players ◽  
Vertical Jumps ◽  
Regular Training

In volleyball, spikes, and block jumps are among the most important movements when earning points and impacting performance. Many studies have found a greater jump height after acutely augmented feedback and extrinsic focus of attention on vertical jump height. However, there are limited studies on the long-term effects of using an overhead target on volleyball-specific vertical jumps (block and spike jumps). Therefore, the aim of the current study was to investigate the effects of using an overhead target on the vertical jump heights of volleyball players. Twenty-five professional male volleyball players (age: 24.44 ± 3.78 years; height: 1.82 ± 8.79 cm; body mass: 80.96 ± 9.37 kg) were randomly assigned either to the experimental group with an overhead target (OHT) ( n = 9), group without an overhead target (WOHT) ( n = 10), or the control group ( n = 8). The OHT group performed vertical jumps with an overhead target before their regular training program, while the WOHT group completed vertical jumps without an overhead target before their regular training program. Meanwhile, the control group performed only their regular training program, which was a 5 week (3 days per week) program. All participants’ spike jump (SPJ) and block jump (BJ) results were assessed before and after the intervention. A repeated-measures analysis of variance (3 × 2) did not reveal any significant between-group interactions for SPJ and BJ ( F = 7.32, p < 0.11 and F = 1.59, p < 0.22 respectively), but significant results were found for the time effect ( F = 96.33, p < 0.01 and F = 132.25, p < 0.01 respectively) and group × time interaction ( F = 42.59, p < 0.01 and F = 61.52, p < 0.01, respectively). While the pre- and post-tests for BJ and SPJ values did not change in the control group ( p > 0.05), both of these values increased in the OHT group (60.00 ± 5.95–67.44 ± 5.98 cm, p < 0.01 for d = 1.24 and 49.00 ± 6.74–56.22 ± 5.29 cm p < 0.01 for d = 1.19, respectively) and WOHT group (57.50 ± 4.86–60.50 ± 4.99 cm, p < 0.01 for d = 0.60 and 47.75 ± 4.65–50.25 ± 3.69 cm, p < 0.01 for d = 0.59). It has been suggested that trainers and professionals can use an overhead target to increase the BJ and SPJ heights of professional volleyball players.

scholarly journals A Biomechanical Investigation of A Single-Limb Squat: Implications for Lower Extremity Rehabilitation Exercise

2008 ◽  
Vol 43 (5) ◽  
pp. 477-482 ◽  
Author(s):  
Jim Richards ◽  
Dominic Thewlis ◽  
James Selfe ◽  
Andrew Cunningham ◽  
Colin Hayes
Keyword(s):  
Repeated Measures ◽  
Knee Flexion ◽  
Knee Extensor ◽  
Rectus Femoris ◽  
Knee Extensors ◽  
Emg Activity ◽  
Repeated Measures Design ◽  
Biomechanical Investigation ◽  
Rehabilitative Intervention ◽  
Integrated Emg

Abstract Context: Single-limb squats on a decline angle have been suggested as a rehabilitative intervention to target the knee extensors. Investigators, however, have presented very little empirical research in which they have documented the biomechanics of these exercises or have determined the optimum angle of decline used. Objective: To determine the involvement of the gastrocnemius and rectus femoris muscles and the external ankle and knee joint moments at 60° of knee flexion while performing a single-limb squat at different decline angles. Design: Participants acted as their own controls in a repeated-measures design. Patients or Other Participants: We recruited 10 participants who had no pain, injury, or neurologic disorder. Intervention(s): Participants performed single-limb squats at different decline angles. Main Outcome Measure(s): Angle-specific knee and ankle moments were calculated at 60° of knee flexion. Angle-specific electromyography (EMG) activity was calculated at 60° of knee flexion. Integrated EMG also was calculated to determine the level of muscle activity over the entire squat. Results: An increase was seen in the knee moments (P &lt; .05) and integrated EMG in the rectus femoris (P &lt; .001) as the decline angle increased. A decrease was seen in the ankle moments as the decline angle increased (P  =  .001), but EMG activity in the gastrocnemius increased between 16° and 24° (P  =  .018). Conclusions: As the decline angle increased, the knee extensor moment and EMG activity increased. As the decline angle increased, the ankle plantar-flexor moments decreased; however, an increase in the EMG activity was seen with the 24° decline angle compared with the 16° decline angle. This indicates that decline squats at an angle greater than 16° may not reduce passive calf tension, as was suggested previously, and may provide no mechanical advantage for the knee.

Vertical Jump Biomechanics Altered With Virtual Overhead Goal

2017 ◽  
Vol 33 (2) ◽  
pp. 153-159 ◽  
Author(s):  
Kevin R. Ford ◽  
Anh-Dung Nguyen ◽  
Eric J. Hegedus ◽  
Jeffrey B. Taylor
Keyword(s):  
Repeated Measures ◽  
Sagittal Plane ◽  
Vertical Jump ◽  
Biomechanical Testing ◽  
Real Life ◽  
Jump Height ◽  
Trunk Flexion ◽  
Jump Performance ◽  
Extrinsic Goals ◽  
Angular Impulse

Virtual environments with real-time feedback can simulate extrinsic goals that mimic real life conditions. The purpose was to compare jump performance and biomechanics with a physical overhead goal (POG) and with a virtual overhead goal (VOG). Fourteen female subjects participated (age: 18.8 ± 1.1 years, height: 163.2 ± 8.1 cm, weight 63.0 ± 7.9 kg). Sagittal plane trunk, hip, and knee biomechanics were calculated during the landing and take-off phases of drop vertical jump with different goal conditions. Repeated-measures ANOVAs determined differences between goal conditions. Vertical jump height displacement was not different during VOG compared with POG. Greater hip extensor moment (P < .001*) and hip angular impulse (P < .004*) were found during VOG compared with POG. Subjects landed more erect with less magnitude of trunk flexion (P = .002*) during POG compared with VOG. A virtual target can optimize jump height and promote increased hip moments and trunk flexion. This may be a useful alternative to physical targets to improve performance during certain biomechanical testing, screening, and training conditions.

Ankle Bracing Decreases Vertical Jump Height and Alters Lower Extremity Kinematics

2016 ◽  
Vol 21 (2) ◽  
pp. 39-46 ◽  
Author(s):  
Bradley Smith ◽  
Tina Claiborne ◽  
Victor Liberi
Keyword(s):  
Lower Extremity ◽  
Vertical Jump ◽  
Plantar Flexion ◽  
Emg Activity ◽  
Jump Height ◽  
Jump Performance ◽  
Vertical Jump Height ◽  
Hip Flexion ◽  
Ankle Plantar Flexion ◽  
Ankle Bracing

The purpose of this study was to determine the effects of ankle bracing on vertical jump performance and lower extremity kinematics and electromyography (EMG) activity. Twenty healthy college athletes participated in two sessions, separated by a minimum of 24 hr. They performed five jumps with no brace on the first day, and five jumps with both ankles braced on the second day. An average of the three highest jumps each day was used for analysis. Braced vertical jump performance significantly decreased (p = .002) as compared with the unbraced condition. In addition, hip flexion (p = .043) and ankle plantar flexion (p = .001) angles were significantly smaller during the braced vertical jump. There was also a significant reduction in soleus muscle EMG (p = .002) during the braced condition.

Electromyographic Analysis of Hip and Trunk Muscle Activity During Side Bridge Exercises in Subjects With Gluteus Medius Weakness

2020 ◽  
pp. 1-6
Author(s):  
Kyung-eun Lee ◽  
Seung-min Baik ◽  
Chung-hwi Yi ◽  
Oh-yun Kwon ◽  
Heon-seock Cynn
Keyword(s):  
Muscle Activity ◽  
Repeated Measures ◽  
Knee Flexion ◽  
Gluteus Maximus ◽  
Random Order ◽  
Gluteus Medius ◽  
Surface Emg ◽  
Trunk Muscles ◽  
Emg Activity ◽  
Abdominal Muscles

Context: Side bridge exercises strengthen the hip, trunk, and abdominal muscles and challenge the trunk muscles without the high lumbar compression associated with trunk extension or curls. Previous research using electromyography (EMG) reports that performance of the side bridge exercise highly activates the gluteus medius (Gmed). However, to the best of our knowledge, no previous research has investigated EMG amplitude in the hip and trunk muscles during side bridge exercise in subjects with Gmed weakness. Objective: The purpose of this study was to examine the EMG activity of the hip and trunk muscles during 3 variations of the side bridge exercise (side bridge, side bridge with knee flexion, and side bridge with knee flexion and hip abduction of the top leg) in subjects with Gmed weakness. Design: Repeated-measures experimental design. Setting: Research laboratory. Patients: Thirty subjects (15 females and 15 males) with Gmed weakness participated in this study. Intervention: Each subject performed 3 variations of the side bridge exercise in random order. Main Outcome Measures: Surface EMG was used to measure the muscle activities of the rectus abdominis, external oblique, longissimus thoracis, multifidus, Gmed, gluteus maximus, and tensor fasciae latae (TFL), and Gmed/TFL muscle activity ratio during 3 variations of the side bridge exercise. Results: There were significant differences in Gmed (F2,56 = 110.054, P < .001), gluteus maximus (F2,56 = 36.416, P < .001), and TFL (F2,56 = 108.342, P < .001) muscles among the 3 side bridge exercises. There were significant differences in the Gmed/TFL muscle ratio (F2,56 = 20.738, P < .001). Conclusion: Among 3 side bridge exercises, the side bridge with knee flexion may be effective for the individuals with Gmed weakness among 3 side bridge exercises to strengthen the gluteal muscles, considering the difficulty of the exercise and relative contribution of Gmed and TFL.

scholarly journals Effect of Different Slopes of the Lower Leg during the Nordic Hamstring Exercise on Hamstring Electromyography Activity

2021 ◽  
pp. 216-221
Author(s):  
Toshiaki Soga ◽  
Daichi Nishiumi ◽  
Atsuya Furusho ◽  
Kei Akiyama ◽  
Norikazu Hirose
Keyword(s):  
Repeated Measures ◽  
Knee Flexion ◽  
Slope Angle ◽  
Lower Leg ◽  
Flexion Angle ◽  
Emg Activity ◽  
Knee Flexion Angle ◽  
Final Phase ◽  
Maximal Voluntary Isometric Contraction ◽  
Repeated Measures Anova

The purpose of this study was to examine whether the NHE with an increased lower leg slope angle would enhance hamstring EMG activity in the final phase of the descend. The hamstring EMG activity was measured, the biceps femoris long head (BFlh) and the semitendinosus (ST). Fifteen male volunteers participated in this study. Subjects performed a prone leg curl with maximal voluntary isometric contraction to normalize the hamstring EMG activity. Subsequently, subjects performed the NHE, with the help of a certified strength and conditioning specialist, while the lower leg slope angle were randomly set at 0° (NH), 20° (N20), and 40° (N40). To compare hamstring EMG activity during the NHE variations, the knee flexion angle was set in the range from 0° to 50°, divided into five phases (0–10°, 10–20°, 20–30°, 30–40° and 40–50°), where 0° indicated that the knee was fully extended. To calculate the knee extension angular velocity, the knee flexion angle divided by time, and break point angle (BPA) was the angle at which 10°/s was exceeded. In the statistical analysis, a two-way repeated measures ANOVA was used for the hamstring EMG activity and a one-way repeated measures ANOVA was used for the BPA. The EMG activity of the BFlh and the ST in N20 and N40 was significantly higher than in NH at knee flexion angle of 0–20° (p < 0.05). For the BPA, NH (57.75° ± 13.28°), N20 (36.27° ± 9.89°) and N40 (16.26° ± 9.58°) were significantly higher in that order (p < 0.05). The results of this study revealed that the NHE with an increased lower leg slope angle shifted the BPA to the lower knee flexion angle and enhanced the hamstring EMG activity in the final phase of the descent.

scholarly journals Evidence for Increased Activation of Persistent Inward Currents in Individuals With Chronic Hemiparetic Stroke

2008 ◽  
Vol 100 (6) ◽  
pp. 3236-3243 ◽  
Author(s):  
Jacob G. McPherson ◽  
Michael D. Ellis ◽  
C. J. Heckman ◽  
Julius P. A. Dewald
Keyword(s):  
Repeated Measures ◽  
Afferent Feedback ◽  
Joint Torque ◽  
Emg Activity ◽  
Tonic Vibration Reflex ◽  
Stretch Reflexes ◽  
Persistent Inward Currents ◽  
Inward Currents ◽  
Hemiparetic Stroke ◽  
Chronic Hemiparetic Stroke

Despite the prevalence of hyperactive stretch reflexes in the paretic limbs of individuals with chronic hemiparetic stroke, the fundamental pathophysiological mechanisms responsible for their expression remain poorly understood. This study tests whether the manifestation of hyperactive stretch reflexes following stroke is related to the development of persistent inward currents (PICs) leading to hyperexcitability of motoneurons innervating the paretic limbs. Because repetitive volleys of 1a afferent feedback can elicit PICs, this investigation assessed motoneuronal excitability by evoking the tonic vibration reflex (TVR) of the biceps muscle in 10 awake individuals with chronic hemiparetic stroke and measuring the joint torque and electromyographic (EMG) responses of the upper limbs. Elbow joint torque and the EMG activity of biceps, brachioradialis, and the long and lateral heads of triceps brachii were recorded during 8 s of 112-Hz biceps vibration (evoking the TVR) and for 5 s after cessation of stimulation. Repeated-measures ANOVA tests revealed significantly ( P ≤ 0.05) greater increases in elbow flexion torque and EMG activity in the paretic as compared with the nonparetic limbs, both during and up to 5 s following biceps vibration. The finding of these augmentations exclusively in the paretic limb suggests that contralesional motoneurons may become hyperexcitable and readily invoke PICs following stroke. An enhanced tendency to evoke PICs may be due to an increased subthreshold depolarization of motoneurons, an increased monoaminergic input from the brain stem, or both.

scholarly journals Enhancement of Countermovement Jump Performance Using a Heavy Load with Velocity-Loss Repetition Control in Female Volleyball Players

2021 ◽  
Vol 18 (21) ◽  
pp. 11530
Author(s):  
Michal Krzysztofik ◽  
Rafal Kalinowski ◽  
Robert Trybulski ◽  
Aleksandra Filip-Stachnik ◽  
Petr Stastny
Keyword(s):  
Body Mass ◽  
Repeated Measures ◽  
Performance Enhancement ◽  
Countermovement Jump ◽  
Mean Power ◽  
Mean Velocity ◽  
Heavy Load ◽  
Jump Performance ◽  
Volleyball Players ◽  
Post Hoc

Although velocity control in resistance training is widely studied, its utilization in eliciting post-activation performance enhancement (PAPE) responses receives little attention. Therefore, this study aimed to evaluate the effectiveness of heavy-loaded barbell squats (BS) with velocity loss control conditioning activity (CA) on PAPE in subsequent countermovement jump (CMJ) performance. Sixteen resistance-trained female volleyball players participated in this study (age: 24 ± 5 yrs.; body mass: 63.5 ± 5.2 kg; height: 170 ± 6 cm; relative BS one-repetition maximum (1RM): 1.45 ± 0.19 kg/body mass). Each participant performed two different conditions: a set of the BS at 80% 1 RM with repetitions performed until a mean velocity loss of 10% as the CA or a control condition without CA (CNTRL). To assess changes in jump height (JH) and relative mean power output (MP), the CMJ was performed 5 min before and throughout the 10 min after the CA. The two-way analysis of variance with repeated measures showed a significant main effect of condition (p = 0.008; η2 = 0.387) and time (p < 0.0001; η2 = 0.257) for JH. The post hoc test showed a significant decrease in the 10th min in comparison to the value from baseline (p < 0.006) for the CNTRL condition. For the MP, a significant interaction (p = 0.045; η2 = 0.138) was found. The post hoc test showed a significant decrease in the 10th min in comparison to the values from baseline (p < 0.006) for the CNTRL condition. No significant differences were found between all of the time points and the baseline value for the CA condition. The CA used in the current study fails to enhance subsequent countermovement jump performance in female volleyball players. However, the individual analysis showed that 9 out of the 16 participants (56%) responded positively to the applied CA, suggesting that the PAPE effect may be individually dependent and should be carefully verified before implementation in a training program.

The Spatial Dependency of Shoulder Muscle Demands for Seated Lateral Hand Force Exertions

2014 ◽  
Vol 30 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Alison C. McDonald ◽  
Elora C. Brenneman ◽  
Alan C. Cudlip ◽  
Clark R. Dickerson
Keyword(s):  
Repeated Measures ◽  
Muscle Activation ◽  
Three Dimensional ◽  
Emg Activity ◽  
Hand Position ◽  
Individual Muscle ◽  
Repeated Measures Analysis ◽  
Spatial Parameters ◽  
Shoulder Complex ◽  
The Right

As the modern workplace is dominated by submaximal repetitive tasks, knowledge of the effect of task location is important to ensure workers are unexposed to potentially injurious demands imposed by repetitive work in awkward or sustained postures. The purpose of this investigation was to develop a three-dimensional spatial map of the muscle activity for the right upper extremity during laterally directed submaximal force exertions. Electromyographic (EMG) activity was recorded from fourteen muscles surrounding the shoulder complex as the participants exerted 40N of force in two directions (leftward, rightward) at 70 defined locations. Hand position in both push directions strongly influenced total and certain individual muscle demands as identified by repeated measures analysis of variance (P< .001). During rightward exertions individual muscle activation varied from 1 to 21% MVE and during leftward exertions it varied from 1 to 27% MVE with hand location. Continuous prediction equations for muscular demands based on three-dimensional spatial parameters were created with explained variance ranging from 25 to 73%. The study provides novel information for evaluating existing and proactive workplace designs, and may help identify preferred geometric placements of lateral exertions in occupational settings to lower muscular demands, potentially mitigating fatigue and associated musculoskeletal risks.

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