Effects of a 2-hour cheerleading practice on dynamic postural stability, knee laxity, and hamstring extensibility

Understanding the Cheerleader as an Orthopaedic Patient: An Evidence-Based Review of the Literature

Cheerleading is a highly popular youth sport in the United States and has been increasingly recognized in recent years for its athleticism and competitive nature. The sport has changed dramatically since its inception. When the sport of cheerleading was first developed, its primary purpose was to entertain crowds and support other athletes. Today, cheerleaders are competitive athletes themselves. Cheerleaders, most of whom are in the pediatric age group, and their parents commonly approach orthopaedic surgeons and sports medicine physicians with questions regarding the risks associated with participation in the sport. Appropriate clinical guidance is especially important for athletes returning to the sport after an injury. However, unlike other popular sports (eg, football, basketball, and volleyball), the intricacies of cheerleading are not well-known to those outside the sport, including many health care providers. Previous studies have reported on the epidemiological patterns of injuries associated with cheerleading and how such aesthetic sports affect the body, finding that fractures and concussions are prevalent and that catastrophic injuries are more common than in most other sports. Here, we provide an evidence-based discussion of 10 pertinent topics regarding cheerleading and its risks to the musculoskeletal system. The purpose of this review is to provide a comprehensive resource for orthopaedic surgeons and sports medicine physicians who care for these athletes.

Does the Type of Toeing Affect Balance in Children With Diplegic Cerebral Palsy? An Observational Cross-sectional Study

Objective

The purpose of the study was to find out effect of toeing on balance in children with diplegic cerebral palsy.

Methods

An observational study was conducted. Thirty children with spastic diplegic cerebral palsy, aged 5 to 8 years, participated in this study. They were classified into 2 groups: group A was children with out-toeing, and group B was children with in-toeing. Foot progression angle was measured by using dynamic footprint, and balance was evaluated using Biodex Balance System equipment. The outcome of interest was postural control (overall stability, anteroposterior stability, and mediolateral stability).

Results

Statistical analysis revealed a significant difference for the tested variables of interest between the 2 tested groups. Multiple pairwise comparison tests revealed that there was significantly better overall stability, anteroposterior stability, and mediolateral stability (P < .05) in group A.

Conclusion

It can be concluded that children with out-toeing have higher balance and stability than children with in-toeing.

Effects of Different Ankle Supports on the Single-Leg Lateral Drop Landing Following Muscle Fatigue in Athletes with Functional Ankle Instability

Background: Ankle support has been utilized for athletes with functional ankle instability (FAI), however, its effect on the landing performance during muscle fatigue is not well understood. This study aimed to examine the effects of ankle supports (ankle brace vs. Kinesio tape) on athletes with FAI following fatigued single-leg landing. Methods: Thirty-three young FAI athletes (CAIT scores < 24) were randomly allocated to control (Cn), ankle brace (AB) and Kinesio tape (KT) groups. All athletes performed single-leg lateral drop landings following ankle fatigue protocol. The fatigue-induced changes in kinetic parameters were measured among three groups. Results: A significant increase in peak vertical ground reaction force (vGRF) was found in the AB group (0.12% body weight (BW)) compared to that of the KT (0.02% BW) and Cn (median = 0.01% BW) groups. Significant decrease in both COP medial-lateral (ML) and anterior-posterior (AP) ranges were also found in the KT group (median = −0.15% foot width (FW) & median = −0.28% foot length (FL)) than those of the Cn group (median = 0.67% FW& median = 0.88% FL). Conclusions: Ankle braces might hamper the ability to absorb the impact force during landing. On the other hand, Kinesio tape might be beneficial for the postural control during landing.

Impact of foot pronation on postural stability: An observational study

OBJECTIVE

To investigate the effect of foot pronation on the postural stability through measuring the dynamic balance including overall stability index (OAI), anteroposterior stability index (APSI) and mediolateral stability index (MLSI).

METHODS

Forty participants from both sexes were selected from the Faculty of Physical Therapy, Cairo University, with a mean age of 23.55 ± 1.74 years. Subjects were divided into two groups: group A (8 males and 12 females) with foot pronation, and group B (9 males and 11 females) with normal feet. The Navicular Drop Test (NDT) was used to determine if the feet were pronated and Biodex Balance System was used to assess dynamic balance at level 8 and level 4 for both groups.

RESULTS

No significant difference was found in dynamic balance, including OAI, APSI and MLSI at stability level 8 (p> 0.05) but, there was a significant difference at stability level 4 (p< 0.05) between the two groups with lower stability in group A.

CONCLUSION

Foot pronation affects the postural stability at stability level four and not affects stability level eight compared with those in the control group.

Effects of Static Stretching and Playing Soccer on Knee Laxity

OBJECTIVE

This study investigated exercise-induced effects of static stretching and playing soccer on anterior tibial translation (ATT) of the knee joint.

DESIGN

Randomized controlled trial.

SETTING

University biomechanics laboratory.

PARTICIPANTS

Thirty-one athletes were randomly assigned into a stretching (26.9 ± 6.2 years, 1.77 ± 0.09 m, 67.9 ± 10.7 kg) and a control group (27.9 ± 7.4 years, 1.75 ± 0.08 m, 72.0 ± 14.9 kg). Thirty-one amateur soccer players in an additional soccer group (25.1 ± 5.6 years, 1.74 ± 0.10 m, 71.8 ± 14.8 kg). All participants had no history of knee injury requiring surgery and any previous knee ligament or cartilage injury.

INTERVENTIONS

The stretching group performed 4 different static stretching exercises with a duration of 2 × 20 seconds interspersed with breaks of 10 seconds. The soccer group completed a 90-minute soccer-specific training program. The control group did not perform any physical activity for approximately 30 minutes.

MAIN OUTCOME MEASURES

Anterior tibial translation was measured with the KT-1000 knee arthrometer at forces of 67 N, 89 N, and maximal manual force (Max) before and after the intervention.

RESULTS

There was a significant increase in ATT after static stretching and playing soccer at all applied forces. Maximal manual testing revealed a mean increase of ATT after static stretching of 2.1 ± 1.6 mm (P < 0.0005) and after playing soccer of 1.0 ± 1.5 mm (P = 0.001). The ATT increase after static stretching at 67 and 89 N is significantly higher than in controls. At maximum manual testing, significant differences were evident between all groups.

CONCLUSIONS

Static stretching and playing soccer increase ATT and may consequently influence mechanical factors of the anterior cruciate ligament. The ATT increase after static stretching was greater than after playing soccer.

CLINICAL RELEVANCE

The observed increase in ATT after static stretching and playing soccer may be associated with changes in kinesthetic perception and sensorimotor control, activation of muscles, joint stability, overall performance, and higher injury risk.

Performance-determining physiological factors in the luge start

In luge, the start is a performance-determining factor. Athletes spend several months in the off-season training to improve starting performance. The aim of this study was to evaluate the influence of different physiological factors on the luge start and identify an appropriate physiological test battery. Thirteen male members of the Austrian national luge team were recruited. All participants completed a test battery that consisted of tests for balance, jumping, isometric truck flexion and extension strength, leg strength, hand grip strength, isometric bench pull and bench press strength, flexibility, and a luge start simulator. Regression analyses of fitness variables and starting speeds revealed relationships (P at least 0.049) except for flexibility, isometric trunk flexion strength, and isometric leg strength at a knee angle of 100 degrees (P at best 0.069). Results showed that a single variable (isometric bench pull strength) explained most of the variance in maximum push-off speed (R2 = 0.750) and suggest that any test battery should include bench pull, trunk extension, and grip strength tests. Bench pull performance might also be a useful tool in the recruitment of athletes.

Balance in single-limb stance in healthy subjects--reliability of testing procedure and the effect of short-duration sub-maximal cycling

BACKGROUND

To assess balance in single-limb stance, center of pressure movements can be registered by stabilometry with force platforms. This can be used for evaluation of injuries to the lower extremities. It is important to ensure that the assessment tools we use in the clinical setting and in research have minimal measurement error. Previous studies have shown that the ability to maintain standing balance is decreased by fatiguing exercise. There is, however, a need for further studies regarding possible effects of general exercise on balance in single-limb stance. The aims of this study were: 1) to assess the test-retest reliability of balance variables measured in single-limb stance on a force platform, and 2) to study the effect of exercise on balance in single-limb stance, in healthy subjects.

METHODS

Forty-two individuals were examined for test-retest reliability, and 24 individuals were tested before (pre-exercise) and after (post-exercise) short-duration, sub-maximal cycling. Amplitude and average speed of center of pressure movements were registered in the frontal and sagittal planes. Mean difference between test and retest with 95% confidence interval, the intraclass correlation coefficient, and the Bland and Altman graphs with limits of agreement, were used as statistical methods for assessing test-retest reliability. The paired t-test was used for comparisons between pre- and post-exercise measurements.

RESULTS

No difference was found between test and retest. The intraclass correlation coefficients ranged from 0.79 to 0.95 in all stabilometric variables except one. The limits of agreement revealed that small changes in an individual's performance cannot be detected. Higher values were found after cycling in three of the eight stabilometric variables.

CONCLUSIONS

The absence of systematic variation and the high ICC values, indicate that the test is reliable for distinguishing among groups of subjects. However, relatively large differences in an individual's balance performance would be required to confidently state that a change is real. The higher values found after cycling, indicate compensatory mechanisms intended to maintain balance, or a decreased ability to maintain balance. It is recommended that average speed and DEV 10; the variables showing the best reliability and effects of exercise, be used in future studies.