Effects of Verbal and Tactile Cues on Gluteal Force Production and Broad Jump Distance

Background

Verbal and tactile cues can increase muscle activity, force production, and kinematics. Several studies demonstrate the effects of verbal and tactile cues on upper extremity muscles, while relatively few examined lower extremity muscles, specifically the gluteals. Studies that observed changes in gluteal function from verbal and tactile cues examined muscle activity via electromyography rather than force production or functional activities such as jumping.

Purpose

The purpose of this study was to measure the effects of verbal and tactile cues on gluteal force production and broad jump distance.

Study Design

Cross-Sectional cohort.

Methods

Gluteus maximus force production and broad jump distance were tested in forty-two healthy male and female university students at baseline and after verbal and tactile cues given in random order. Gluteus maximus force was measured using handheld dynamometry and reported in kilograms. Verbal cues included "push, push, push" before both tests. The examiner provided tactile cues to the gluteus maximus before force production testing, and the participant provided tactile cues to both gluteus maximus muscles before performing the broad jump. Performance on the broad jump was measured in centimeters. Descriptive statistics and test-retest reliability via Pearson correlation coefficients were calculated, differences in performance between sexes were analyzed with an independent t-test, and changes in force production and jump distance from baseline were analyzed using a one-way ANOVA.

Results

Mean gluteus maximus force production following verbal cues significantly increased (p = 0.000) by 13.48% (3.83 kg) compared to the control condition, while gluteal force production following the tactile cues was not significantly different. Broad jump distance following the verbal cues significantly increased (p = 0.000) 3.99% (7.71 cm) compared to the control condition and significantly increased (p = 0.000) by 2.95% (5.71 cm) following the tactile cues. There were no significant differences in performances between males and females. The test-retest reliability of all measurements was 0.97-0.99.

Conclusion

Verbal cues significantly increased gluteus maximus force production and broad jump distance. Tactile cues significantly increased broad jump distance but had no significant effect on gluteus maximus force. These results have implications for clinical testing and athletic performance when gluteus maximus force and jump distance are concerned.

Level of Evidence

3.

Hip and Trunk Variables in University Students with and without Recurrent Low Back Pain

Background

Low back pain (LBP) is a leading cause of disability. Recurrent low back pain (rLBP) is defined as two or more episodes of LBP in a 12-month period, each lasting more than 24 hours and separated by at least one pain-free month. Many studies have shown that hip and trunk variables have an influence on LBP. However, most of these are studies of participants with acute or chronic LBP rather than rLBP.

Purpose

To examine the difference between hip and trunk variables of university students with and without rLBP.

Study Design

Cross-Sectional.

Methods

Participants with and without rLBP between 18 and 35 years of age not currently undergoing clinical orthopedic care were recruited for this cross-sectional study. Bilateral hip range of motion (ROM) and trunk ROM were measured with a goniometer or measuring tape (hip motions in all planes along with trunk flexion, extension, and lateral flexion). Strength of the hip extensors, abductors, and external rotators was measured using a handheld dynamometer, and a single-leg bridge endurance test was performed to assess differences and correlations between outcomes.

Results

Twenty-six subjects aged 18 to 35 years with rLBP (n=10) and without rLBP (n=16) participated. Statistically significant differences between the two groups were found for right and left hip flexion (p = 0.029 and 0.039, respectively), right hip adduction (p = 0.043), and right hip extension (p = 0.021). No significant differences were found between groups for strength, endurance, or other ROM measures.

Conclusion

The findings of this study show statistically significant although clinically non-meaningful differences in hip flexion, extension, and adduction ROM in the rLBP group compared to the control group. This lack of clinically meaningful difference may be relevant to testing procedures and treatment of patients or athletes with rLBP. This study also suggests that hip strength and endurance may not play a major role in the development or treatment of rLBP. Level of Evidence: 3.

The Reliability and Validity of Gluteal Endurance Measures (GEMs)

BACKGROUND

The gluteals have unique morphology related to muscle endurance, including moderate fiber sizes and a majority of Type I endurance fibers. Evidence suggests gluteal endurance is related to low back pain, running kinematics, balance, posture, and more. However, reliable and valid measures specific to gluteal endurance are lacking in the literature.

HYPOTHESIS/PURPOSE

The purpose of this study was to examine the intra- and inter-rater reliability of two gluteal endurance measures (GEMs) for clinical use. It also aimed to examine validity for the two measures by using electromyography (EMG), recording reasons for task failure, and analyzing differences between demographic groups.

STUDY DESIGN

Cross-Sectional.

METHODS

Sixty-eight males and females with and without recurrent low back pain aged 18-35 years were recruited from a university population. Electromyography electrodes were placed on subjects' gluteus maximus and gluteus medius, and each subject performed three trials of GEM-A (abduction endurance) and GEM-B (bridging endurance). Hold times, EMG median frequency (MF) data, and subjective reasons for task failure were analyzed.

RESULTS

Both GEMs demonstrated high intra-rater reliability (ICC = 0.87-0.94) and inter-rater reliability (ICC = 0.99). Mean hold times were 104.83 ± 34.11 seconds for GEM-A (abduction endurance) and 81.03 ± 24.79 seconds for GEM-B (bridging endurance). No statistically significant difference was found between subjects with and without recurrent LBP. Median frequency data validated the onset of gluteal fatigue during both measures. Posterolateral hip (gluteal) fatigue was reported as the primary reason for task failure in 93% and 86% of subjects for GEM-A and GEM-B, respectively.

CONCLUSION

This seminal study of GEM-A (abduction endurance) and GEM-B (bridging endurance) found both measures to be reliable and valid measures of gluteal endurance. Further examination of the GEMs in samples with different types of LBP or hip pain is recommended.

LEVEL OF EVIDENCE

3.

Gluteal Muscle Activation During Common Yoga Poses

BACKGROUND

Approximately 24% of physical therapists report regularly using yoga to strengthen major muscle groups. Although clinicians and athletes often use yoga as a form of strength training, little is known about the activation of specific muscle groups during yoga poses, including the gluteus maximus and medius.

HYPOTHESIS/PURPOSE

The purpose of this study was to measure gluteus maximimus and gluteus medius activation via electromyography (EMG) during five common yoga poses. A secondary purpose of the current study was to examine differences in muscle activation between sexes and experience levels.

STUDY DESIGN

Cross-Sectional.

METHODS

Thirty-one healthy males and females aged 18-35 years were tested during five yoga poses performed in a randomized order. Surface EMG electrodes were placed on subjects' right gluteus maximus and gluteus medius. Subjects performed the poses on both sides following a maximal voluntary isometric contraction (MVIC) test for each muscle. All yoga pose EMG data were normalized to the corresponding muscle MVIC data.

RESULTS

Highest gluteus maximus activation occurred during Half Moon Pose on the lifted/back leg (63.3% MVIC), followed by the stance/front leg during Half Moon Pose (61.7%), then the lifted/back leg during Warrior Three Pose (46.1%). Highest gluteus medius activation occurred during Half Moon Pose on the lifted/back leg (41.9%), followed by the lifted/back leg during the Warrior Three Pose (41.6%). A significant difference was found in %MVIC of gluteus medius activity between male and female subjects (p = 0.026), and between experienced and inexperienced subjects (p = 0.050), indicating higher activation among males and inexperienced subjects, respectively.

CONCLUSION

Half Moon Pose and Warrior Three Pose elicited the highest activation for both the gluteus maximus and the gluteus medius. Higher gluteus medius activation was seen in males and inexperienced subjects compared to their female and experienced counterparts.

LEVEL OF EVIDENCE

3.

BUILDING A BETTER GLUTEAL BRIDGE: ELECTROMYOGRAPHIC ANALYSIS OF HIP MUSCLE ACTIVITY DURING MODIFIED SINGLE-LEG BRIDGES

BACKGROUND

Gluteal strength plays a role in injury prevention, normal gait patterns, eliminating pain, and enhancing athletic performance. Research shows high gluteal muscle activity during a single-leg bridge compared to other gluteal strengthening exercises; however, prior studies have primarily measured muscle activity with the active lower extremity starting in 90 ° of knee flexion with an extended contralateral knee. This standard position has caused reports of hamstring cramping, which may impede optimal gluteal strengthening.

HYPOTHESIS/PURPOSE

The purpose of this study was to determine which modified position for the single-leg bridge is best for preferentially activating the gluteus maximus and medius.

STUDY DESIGN

Cross-Sectional.

METHODS

Twenty-eight healthy males and females aged 18-30 years were tested in five different, randomized single-leg bridge positions. Electromyography (EMG) electrodes were placed on subjects' gluteus maximus, gluteus medius, rectus femoris, and biceps femoris of their bridge leg (i.e., dominant or kicking leg), as well as the rectus femoris of their contralateral leg. Subjects performed a maximal voluntary isometric contraction (MVIC) for each tested muscle prior to performing five different bridge positions in randomized order. All bridge EMG data were normalized to the corresponding muscle MVIC data.

RESULTS

A modified bridge position with the knee of the bridge leg flexed to 135 ° versus the traditional 90 ° of knee flexion demonstrated preferential activation of the gluteus maximus and gluteus medius compared to the traditional single-leg bridge. Hamstring activation significantly decreased (p < 0.05) when the dominant knee was flexed to 135 ° (23.49% MVIC) versus the traditional 90 ° (75.34% MVIC), while gluteal activation remained similarly high (51.01% and 57.81% MVIC in the traditional position, versus 47.35% and 57.23% MVIC in the modified position for the gluteus maximus and medius, respectively).

CONCLUSION

Modifying the traditional single-leg bridge by flexing the active knee to 135 ° instead of 90 ° minimizes hamstring activity while maintaining high levels of gluteal activation, effectively building a bridge better suited for preferential gluteal activation.

LEVEL OF EVIDENCE

3.

What performance characteristics determine elite versus nonelite athletes in the same sport?

Context:

There are significant data comparing elite and nonelite athletes in anaerobic field and court sports as well as endurance sports. This review delineates specific performance characteristics in the elite athlete and may help guide rehabilitation.

Evidence Acquisition:

A Medline search from April 1982 to April 2012 was undertaken for articles written in English. Additional references were accrued from reference lists of research articles.

Results:

In the anaerobic athlete, maximal power production was consistently correlated to elite performance. Elite performance in the endurance athlete is more ambiguous, however, and appears to be related to the dependent variable investigated in each individual study.

Conclusion:

In anaerobic field and court sport athletes, maximal power output is most predictive of elite performance. In the endurance athlete, however, it is not as clear. Elite endurance athletes consistently test higher than nonelite athletes in running economy, anaerobic threshold, and VO_2max.