The Acute Effects of Foam Rolling and Dynamic Stretching on Athletic Performance: A Critically Appraised Topic.

Clinical Scenario: Dynamic stretching and foam rolling are commonly used by athletes to reduce injury and enhance recovery, thereby improving athletic performance. In contrast to dynamic stretching, little research has been conducted on the acute effects of foam rolling as part of the preexercise warm-up routine. Previously, when researchers implemented foam rolling with static stretching as a warm-up, some found that foam rolling slightly improved flexibility and performance outcomes. More recent research has shown that dynamic stretching is favorable to static stretching when used as a warm-up strategy. Therefore, adding foam rolling to dynamic stretching is hypothesized to create more significant improvements in flexibility and performance compared with adding foam rolling to static stretching. Focused Clinical Question: In active individuals, does foam rolling in addition to dynamic stretching lead to enhanced performance compared with dynamic stretching alone? Summary of Key Findings: Four randomized controlled trials were included. Two studies concluded that the addition of foam rolling to dynamic stretching increased vertical jump height more than dynamic stretching alone, while 2 studies found no difference between these treatment groups. Two studies concluded that the addition of foam rolling increased agility performance compared with dynamic stretching alone, while one study found no difference between treatment groups and one study did not measure agility. All 4 studies reviewed concluded that foam rolling did not improve flexibility more than dynamic stretching alone. Clinical Bottom Line: Foam rolling in conjunction with dynamic stretching may further improve an athlete's agility and power output; however, little improvement has been observed with foam rolling in regard to athlete flexibility when compared with completing dynamic stretching programs alone. Strength of Recommendation: Inconsistent findings from 4 randomized controlled trials suggest there is Grade C evidence to support the inclusion of foam rolling in a dynamic warm-up.

Lack of neuromuscular origins of adaptation after a long-term stretching program.

CONTEXT: Static stretching is commonly used during the treatment and rehabilitation of orthopedic injuries to increase joint range of motion (ROM) and muscle flexibility. Understanding the physiological adaptations that occur in the neuromuscular system as a result of long-term stretching may provide insight into the mechanisms responsible for changes in flexibility. OBJECTIVE: To examine possible neurological origins and adaptations in the Ia-reflex pathway that allow for increases in flexibility in ankle ROM, by evaluating the reduction in the synaptic transmission of Ia afferents to the motoneuron pool. DESIGN: Repeated-measures, case-controlled study. SETTING: Sports medicine research laboratory. PARTICIPANTS: 40 healthy volunteers with no history of cognitive impairment, neurological impairment, or lower extremity surgery or injury within the previous 12 mo. INTERVENTION: Presynaptic and postsynaptic mechanisms were evaluated with a chronic stretching pro- tocol. Twenty subjects stretched 5 times a wk for 6 wk. All subjects were measured at baseline, 3 wk, and 6 wk. MAIN OUTCOME MEASURES: Ankle-dorsiflexion ROM, Hmax:Mmax, presynaptic inhibition, and disynaptic reciprocal inhibition. RESULTS: Only ROM had a significant interaction between group and time, whereas the other dependent variables did not show significant differences. The experimental group had significantly improved ROM from baseline to 3 wk (mean 6.2 ± 0.9, P < .001), 3 wk to 6 wk (mean 5.0 ± 0.8, P < .001), and baseline to 6 wk (mean 11.2 ±0.9, P < .001). CONCLUSIONS: Ankle dorsiflexion increased by 42.25% after 6 wk of static stretching, but no significant neurological changes resulted at any point of the study, contrasting current literature. Significant neuromuscular origins of adaptation do not exist in the Ia-reflex-pathway components after a long-term stretching program as currently understood. Thus, any increases in flexibility are the result of other factors, potentially mechanical changes or stretch tolerance.

Intersession reliability of Hoffmann reflex gain and presynaptic inhibition in the human soleus muscle.

UNLABELLED: Hayes BT, Hicks-Little CA, Harter RA, Widrick JJ, Hoffman MA. Intersession reliability of Hoffmann reflex gain and presynaptic inhibition in the human soleus muscle. OBJECTIVE: To determine the day-to-day reliability of Hoffmann reflex (H-reflex) gain and presynaptic inhibition of spinal reflexes in the human soleus muscle. DESIGN: Controlled trial. SETTING: Research laboratory. PARTICIPANTS: Volunteers (N=30; mean +/- SD age, 23.4+/-3.9y; height, 175.64+/-10.87cm; mass, 84.50+/-24.18kg) with no history of lower extremity pathology and/or injury participated. INTERVENTIONS: Subjects lay prone with the head, shoulders, arms, and hips supported in a static position by a massage body pillow and the ankle positioned at 90 degrees . Recording electrodes were placed over the soleus and tibialis anterior muscle bellies, and the stimulating electrodes were positioned over the tibial nerve in the popliteal space and the common peroneal nerve near the fibular head. MAIN OUTCOME MEASURES: The H-reflex and motor wave recruitment curves were then measured and recorded. Presynaptic inhibition was also assessed in the soleus muscle, and a conditioning stimulation of the common peroneal nerve (1 x motor threshold = motor threshold) was used prior to soleus H-reflex measurement. Two testing sessions took place between 2 and 7 days, and each session occurred at the same time of day. RESULTS: Assessments of H-reflex gain and presynaptic inhibition yielded test-retest reliability of R equal to . 95 and .91, respectively. CONCLUSIONS: Measures of presynaptic inhibition and H-reflex gain (H slope/M slope) in the human soleus muscle are consistent and reliable day to day.

Shoulder joint position sense after thermal, open, and arthroscopic capsulorrhaphy for recurrent anterior instability.

Identifying the optimal surgical treatment for recurrent, anterior glenohumeral instability remains a challenge. Our purpose was to compare shoulder joint position sense among open, arthroscopic, and thermal capsulorrhaphy patients after repair of recurrent anterior instability and to compare these patients to healthy, control subjects. Sixty-seven adults (45 post-surgical patients, 22 controls) volunteered to participate in the study. We evaluated both the surgically repaired and contralateral shoulders of 45 capsulorrhaphy patients (28 men, 17 women) and compared their results with the normal bilateral shoulders of 22 age-matched controls (11 men, 11 women). Accuracy of joint position sense was quantified via passive reproduction of target positions set at 60% and 90% of each subject's maximum passive external rotation (ER(max)). We observed no significant differences in joint position sense between the repaired shoulders and the contralateral normal shoulders of all groups of capsulorrhaphy patients. Open and thermal capsulorrhaphy patients demonstrated significantly better (P

Validity and reliability of limits-of-stability testing: a comparison of 2 postural stability evaluation devices.

CONTEXT: A lack of published comparisons between measures from commercially available computerized posturography devices and the outcome measures used to define the limits of stability (LOS) makes meaningful interpretation of dynamic postural stability measures difficult. OBJECTIVES: To compare postural stability measures between and within devices to establish concurrent and construct validity and to determine test-retest reliability for LOS measures generated by the NeuroCom Smart Balance Master and the Biodex Balance System. DESIGN: Cross-sectional study. SETTING: Controlled research laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 23 healthy participants with no vestibular or visual disabilities or lower limb impairments. INTERVENTION(S): The LOS were assessed during 2 laboratory test sessions 1 week apart. MAIN OUTCOME MEASURE(S): Three NeuroCom LOS variables (directional control, endpoint excursion, and movement velocity) and 2 Biodex LOS variables (directional control, test duration). RESULTS: Test-retest reliability ranged from high to low across the 5 LOS measures (intraclass correlation coefficient [2,k] = 0.82 to 0.48). Pearson correlations revealed 4 significant relationships (P < .05) between and within the 2 computerized posturography devices (r = 0.42 to -0.65). CONCLUSIONS: Based on the wide range of intraclass correlation values we observed for the NeuroCom measures, clinicians and researchers alike should establish the reliability of LOS testing for their own clinics and laboratories. The low to moderate reliability outcomes observed for the Biodex measures were not of sufficient magnitude for us to recommend using the LOS measures from this system as the gold standard. The moderate Pearson interclass correlations we observed suggest that the Biodex and NeuroCom postural stability systems provided unique information. In this study of healthy participants, the concurrent and construct validity of the Biodex and NeuroCom LOS tests were not definitively established. We recommend that this study be repeated with a clinical population to further explore the matter.

The interrelationships among sex hormone concentrations, motoneuron excitability, and anterior tibial displacement in women and men.

CONTEXT: Sex hormone fluctuations have been implicated as a contributing factor to the high rates of noncontact injury to the anterior cruciate ligament in females. OBJECTIVE: To determine the strength of the relationships among variables of sex hormone concentrations, motoneuron excitability, and anterior tibial displacement (ATD) in women and men and to determine if these relationships differ between the sexes. DESIGN: Cohort study. SETTING: Sports medicine laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty-eight regularly menstruating women (age = 22.4 +/- 3.4 years) and 15 men (age = 22.3 +/- 3.7 years) participated in the study. INTERVENTION(S): Fluctuations in sex hormones were determined for the participants. Female participants were tested every other day of their menstrual cycles, whereas male participants were tested every fourth day during the 28-day period. MAIN OUTCOME MEASURE(S): We measured Hoffmann reflexes (maximum Hoffmann reflex [H(max)] to maximum M-wave [M(max)] ratio in the soleus), ATD under a 134-N load, and saliva concentrations of estrogen and progesterone. The independent variable was sex. Pearson product moment correlation coefficients were calculated for each participant by pairing measurements made on the same day. Two-tailed independent-samples t tests were used to determine the difference between the male and female correlations for each variable. RESULTS: Over the course of the study, the relationships between H(max)ratioM(max) and estrogen, H(max)ratioM(max) and progesterone, ATD and estrogen, and ATD and progesterone were not different between the sexes. However, the relationship between ATD and progesterone was different between the sexes (P = .036). CONCLUSIONS: The observed correlations did not support our hypothesis that the relationships between sex hormone levels and reflex activity or between sex hormone levels and ATD would be different for women compared with men. If sex hormone concentrations significantly contribute to anterior cruciate ligament ruptures because of changes in laxity or in motoneuron excitability, their mechanism of action is likely multifactorial and complex.