JoEllen M. Sefton

Sensorimotor function as a predictor of chronic ankle instability

BACKGROUNDnRecurrent ankle injury occurs in 70% of individuals experiencing a lateral ankle sprain. The cause of this high level of recurrence is currently unknown. Researchers have begun to investigate sensorimotor deficits as one possible cause with inconclusive and often conflicting results. The purpose of this study was to further the understanding of the role of sensorimotor deficits in the chronically unstable ankle by establishing which specific measures best distinguish between chronically unstable and healthy ankles.nnnMETHODSnTwenty-two participants with chronic ankle instability and 21 healthy matched controls volunteered. Twenty-five variables were measured within four sensorimotor constructs: joint kinesthesia (isokinetic dynamometer), static balance (force plate), dynamic balance (Star Excursion Balance Test) and motoneuron pool excitability (electromyography).nnnFINDINGSnThe above variables were evaluated using a discriminant function analysis [WilksLambda=0.536 chi(2)(7, N=43)=22.118, P=0.002; canonical correlation=0.681]. The variables found to be significant were then used to assess group discrimination. This study revealed that seven separate variables from the static balance (anterior/posterior and medial/lateral displacement and velocity) and motoneuron pool excitability constructs (single-legged recurrent inhibition and single- and double-legged paired reflex depression) accurately classified over 86% of participants with unstable ankles.nnnINTERPRETATIONnThese results suggest that a multivariate approach may be necessary to understand the role of sensorimotor function in chronic ankle instability, and to the development of appropriate rehabilitation and prevention programs. Out of the four overall constructs, only two were needed to accurately classify the participants into two groups. This indicates that static balance and motoneuron pool excitability may be more clinically important in treatment and rehabilitation of chronic ankle instability than functional balance or joint kinesthesia.

Six Weeks of Balance Training Improves Sensorimotor Function in Individuals With Chronic Ankle Instability

STUDY DESIGNnProspective cohort study.nnnOBJECTIVEnTo assess the effect of 6 weeks of balance training on sensorimotor measures previously found to be deficient in participants with chronic ankle instability (CAI).nnnBACKGROUNDnCAI is the tendency toward repeated ankle sprains and recurring symptoms, occurring in 40% to 70% of individuals who have previously sustained a lateral ankle sprain. Recent studies have found deficits in sensorimotor measures in individuals with CAI. As balance training is a common component of ankle rehabilitation, understanding its effect on the sensorimotorsystem in individuals with CAI may enable us to optimize protocols to better utilize this rehabilitation method.nnnMETHODSnTwelve participants with CAI and 9 healthy volunteers participated. Independent variables were group (CAI, control) and time (pretraining, posttraining). Participants with CAI who completed a 6-week balance training program and healthy controls who did not get any training were pretested and posttested at the beginning and at the end of 6 weeks.nnnRESULTSnThe individuals in the CAI group who performed balance training demonstrated better performance than control participants on baseline adjusted posttraining measures of dynamic balance in the anterior medial (P = .021), medial (P = .048), and posterior medial directions (P = .030); motoneuron pool excitability Hmax/Mmax ratio (P = .044) and single-limb presynaptic inhibition (P = .012); and joint position sense inversion variable error (P = .017). It may be of note that no systematic differences were detected for static balance or plantar flexion joint position sense tasks.nnnCONCLUSIONSnAfter 6 weeks of balance training, individuals with CAI demonstrated enhanced dynamic balance, inversion joint position sense, and changes in motoneuron pool excitability compared to healthy controls who did not train.nnnLEVEL OF EVIDENCEnTherapy, level 2b.

Therapeutic Massage of the Neck and Shoulders Produces Changes in Peripheral Blood Flow When Assessed with Dynamic Infrared Thermography

OBJECTIVEnThis studys objective was to determine the effect of therapeutic massage on peripheral blood flow utilizing dynamic infrared thermography in a constant temperature/humidity thermal chamber to assess noncontact skin temperature.nnnDESIGNnThe design was a repeated-measures crossover experimental design; the independent variable was treatment condition (massage, light touch, control).nnnSETTINGnThe study setting was a university research laboratory.nnnSUBJECTSnSeventeen (17) healthy volunteers (8 males/9 females; age = 23.29 +/- 3.06) took part in the study.nnnINTERVENTIONSnOne (1) 20-minute neck and shoulder therapeutic massage treatment was performed for each of the three treatment conditions.nnnOUTCOME MEASURESnThe dependent variable was noncontact, mean skin temperature in 15 regions measured at 6 time points (pretest and 15, 25, 35, 45, and 60 minutes post-test) for each treatment condition.nnnRESULTSnThe massage treatment produced significant elevations in temperature in five regions: anterior upper chest (p = 0.04), posterior neck (p = 0.0006), upper back (p = 0.0005), posterior right arm (p = 0.03), and middle back (p = 0.02). Massage therapy produced significant increases in temperature over time, compared to the other conditions, in the anterior upper chest, and posterior neck, upper back, right arm, and the middle back. Additionally, the temperatures remained above baseline levels after 60 minutes. Interestingly, the massage treatment produced significant temperature elevations in two nonmassaged areas posterior right arm and middle back.nnnCONCLUSIONSnThese changes in temperature suggest corresponding changes in peripheral blood flow in the treated areas as well as in adjacent not-massaged areas. Moreover, the results suggest dynamic infrared thermography as a useful tool to measure noninvasive, noncontact changes in peripheral blood flow for massage therapy research.

Segmental Spinal Reflex Adaptations Associated With Chronic Ankle Instability

OBJECTIVEnTo further understanding of the role that segmental spinal reflexes play in chronic ankle instability (CAI).nnnDESIGNnA 2 x 2 repeated-measures case-control factorial design. The independent variables were ankle group with 2 levels (healthy, CAI) and stance with 2 levels (single, double legged).nnnSETTINGnUniversity research laboratory.nnnPARTICIPANTSnTwenty-two participants with CAI and 21 matched healthy controls volunteered.nnnINTERVENTIONSnNot applicable.nnnMAIN OUTCOME MEASURESnThe dependent variables were 2 measures of motoneuron pool excitability: paired reflex depression (PRD) and recurrent inhibition.nnnRESULTSnA 2 x 2 repeated-measures multivariate analysis of variance revealed a significant interaction between group and stance on the linear combination of PRD and recurrent inhibition variables (Wilks lambda=.808, F(2,40)=4.77, P=.014). Follow-up univariate F tests revealed an interaction between group and stance on the PRD (F(1,41)=9.74, P=.003). Follow-up dependent t tests revealed a significant difference between single- and double-legged PRD in the healthy participants (t(20)=-3.76, P=.001) with no difference in CAI participants (t(21)=-0.44, P=.67). Finally, there was a significant difference in recurrent inhibition between healthy (mean, 83.66) and CAI (mean, 90.27) (P=.004).nnnCONCLUSIONSnThis study revealed that, compared with healthy participants, CAI participants were less able to modulate PRD when going from a double- to a single-legged stance. Additionally, CAI participants showed higher overall levels of recurrent inhibition when compared with healthy matched controls.

Physiological and clinical changes after therapeutic massage of the neck and shoulders

Little is known regarding the physiological and clinical effects of therapeutic massage (TM) even though it is often prescribed for musculoskeletal complaints such as chronic neck pain. This study investigated the influence of a standardized clinical neck/shoulder TM intervention on physiological measures assessing α-motoneurone pool excitability, muscle activity; and the clinical measure of range of motion (ROM) compared to a light touch and control intervention. Flexor carpi radialis (FCR) α-motoneurone pool excitability (Hoffmann reflex), electromyography (EMG) signal amplitude of the upper trapezius during maximal muscle activity, and cervical ROM were used to assess possible physiological changes and clinical effects of TM. Sixteen healthy adults participated in three, 20 min interventions: control (C), light touch (LT) and therapeutic massage (TM). Analysis of Covariance indicated a decrease in FCR α-motoneurone pool excitability after TM, compared to both the LT (p = 0.0003) or C (p = 0.0007) interventions. EMG signal amplitude decreased after TM by 13% (p < 0.0001), when compared to the control, and 12% (p < 0.0001) as compared to LT intervention. The TM intervention produced increases in cervical ROM in all directions assessed: flexion (p < 0.0001), lateral flexion (p < 0.0001), extension (p < 0.0001), and rotation (p < 0.0001). TM of the neck/shoulders reduced the α-motoneurone pool excitability of the flexor carpi radialis after TM, but not after the LT or C interventions. Moreover, decreases in the normalized EMG amplitude during MVIC of the upper trapezius muscle; and increases in cervical ROM in all directions assessed occurred after TM, but not after the LT or C interventions.

Cryotherapy and ankle bracing effects on peroneus longus response during sudden inversion

Cryotherapy and ankle bracing are often used in conjunction as a treatment for ankle injury. No studies have evaluated the combined effect of these treatments on reflex responses during inversion perturbation. This study examined the combined influence of ankle bracing and joint cooling on peroneus longus (PL) muscle response during ankle inversion. A 2x2 RM factorial design guided this study; the independent variables were: ankle brace condition (lace-up brace, control), and treatment (ice, control), and the dependent variables studied were PL stretch reflex latency (ms), and PL stretch reflex amplitude (% of max). Twenty-four healthy participants completed 5 trials of a sudden inversion perturbation to the ankle/foot complex under each ankle brace and cryotherapy treatment condition. No two-way interaction was observed between ankle brace and treatment conditions on PL latency (P=0.283) and amplitude (P=0.884). The ankle brace condition did not differ from control on PL latency and amplitude. Cooling the ankle joint did not alter PL latency or amplitude compared to the no-ice treatment. Ankle bracing combined with joint cooling does not have a deleterious effect on dynamic ankle joint stabilization during an inversion perturbation in normal subjects.

Mechanical Joint Laxity Associated With Chronic Ankle Instability: A Systematic Review

Context: Lateral ankle sprains can manifest into chronic mechanical joint laxity when not treated effectively. Joint laxity is often measured through the use of manual stress tests, stress radiography, and instrumented ankle arthrometers. Purpose: To systematically review the literature to establish the influence of chronic ankle instability (CAI) on sagittal and frontal plane mechanical joint laxity. Data Sources: Articles were searched with MEDLINE (1966 to October 2008), CINAHL (1982 to October 2008), and the Cochrane Database of Systematic Reviews (to October 2008) using the key words chronic ankle instability and joint laxity, functional ankle instability and joint laxity, and lateral ankle sprains and joint laxity. Study Selection: To be included, studies had to employ a case control design; mechanical joint laxity had to be measured via a stress roentogram, an instrumented ankle arthrometer, or ankle/foot stress-testing device; anteroposterior inversion or eversion ankle-subtalar joint complex laxity had to be measured; and means and standard deviations of CAI and control groups had to be provided. Data Extraction: One investigator assessed each study based on the criteria to ensure its suitability for analysis. The initial search yielded 1378 potentially relevant articles, from which 8 were used in the final analysis. Once the study was accepted for inclusion, its quality was assessed with the PEDro scale. Data Synthesis: Twenty-one standardized effect sizes and their 95% confidence intervals were computed for each group and dependent variable. CAI produced the largest effect on inversion joint laxity; 45% of the effects ranged from 0.84 to 2.61. Anterior joint laxity measures were influenced second most by CAI (effects, 0.32 to 1.82). CAI had similar but less influence on posterior joint laxity (effects, −0.06 to 0.68) and eversion joint laxity (effects, 0.03 to 0.69). Conclusion: CAI has the largest effect with the most variability on anterior and inversion joint laxity measurements, consistent with the primary mechanism of initial injury.

Effects of stance width on performance and postural stability in national-standard pistol shooters

Abstract The aim of the present study was to determine whether changing stance width would result in a corresponding change in postural and/or pistol stability. Twelve national-standard male air pistol shooters performed 10 shots each at five stance widths (30 cm, 45 cm, 60 cm, 75 cm, and 90 cm). Postural stability was determined by measuring centre-of-pressure changes with a dual force-platform system. Shooting mechanics measures were determined by a NOPTEL ST-2000 optoelectronic training system. Medial-lateral centre-of-pressure excursion (F 4,44 = 7.17, P < 0.001, effect size = 0.99) and speed (F 4,44 = 77.03, P < 0.001, effect size = 3.88) were reduced as stance width decreased. Centre of gravity fine (the percentage of time held within an area the size of the ten-ring) improved during narrower stance widths (F 4,32 = 12.49, P < 0.001, effect size = 0.71). Our findings suggest that stance width affects postural and pistol stability in national-standard air pistol athletes. Moreover, the current method of suggesting a wider stance to improve shooting performance should be reconsidered and perhaps air-pistol shooters should use a 30-cm stance width to improve postural stability and shooting performance.

Acute physiological effects of whole body vibration (WBV) on central hemodynamics, muscle oxygenation and oxygen consumption in individuals with chronic spinal cord injury

Abstract Purpose: (1) Investigate the acute effects of whole body vibration (WBV) on central hemodynamic responses, muscle oxygenation and oxygen consumption () in individuals with spinal cord injury (SCI) versus sex, age and activity-matched able-bodied (AB) individuals. (2) Assess the effects of three WBV frequencies on all outcome measures. Methods: Eleven males with SCI and 10 AB individuals were recruited. Subjects completed three WBV exercise sessions at 30, 40 and 50u2009Hz. Heart rate (HR), mean arterial blood pressure (MAP), stroke volume (SV), cardiac output (CO), and relative changes in oxygenated (Δ[HbMbO2]), deoxygenated (Δ[HHbMb]) and total (Δ[HbMbtot]) heme groups were obtained when steady state was achieved for: pre-WBV sitting, pre-WBV standing, WBV and post-WBV standing. Results: Both groups demonstrated small but significant increases in , Δ[HbMbO2] and Δ[HbMbtot]; but the increases were larger in the SCI group. A significant decrease Δ[HHbMb] was observed in the SCI group. No frequency effect was observed. Conclusion: The WBV responses do not appear sufficient to induce cardiovascular benefits in the SCI population. WBV may be helpful for individuals with SCI in improving lower limb peripheral blood flow and coping with orthostatic hypotension symptoms earlier in their rehabilitation programs. Implications for Rehabilitation Increased muscle oxygenation and blood flow observations in response to WBV suggest a possible application of WBV for increasing lower extremity blood flow and/or oxygen saturation in individuals with SCI. WBV may be incorporated into the rehabilitation programs for reducing thrombosis susceptibility in individuals with SCI. Blood pressure in individuals with SCI appeared to be maintained much better in the upright position when WBV is applied. This could be helpful in the rehabilitation of SCI patients by allowing them to avoid the difficulties of orthostatic hypotension earlier in their rehabilitation programs.

Evaluation of 2 Heat-Mitigation Methods in Army Trainees

CONTEXTnu2003Heat injury is a significant threat to military trainees. Different methods of heat mitigation are in use across military units. Mist fans are 1 of several methods used in the hot and humid climate of Fort Benning, Georgia.nnnOBJECTIVESnu2003To determine if (1) the mist fan or the cooling towel effectively lowered participant core temperature in the humid environment found at Fort Benning and (2) the mist fan or the cooling towel presented additional physiologic or safety benefits or detriments when used in this environment.nnnDESIGNnu2003Randomized controlled clinical trial.nnnSETTINGnu2003Laboratory environmental chamber.nnnPATIENTS OR OTHER PARTICIPANTSnu2003Thirty-five physically active men aged 19 to 35 years.nnnINTERVENTION(S)nu2003(1) Mist fan, (2) commercial cooling towel, (3) passive-cooling (no intervention) control. All treatments lasted 20 minutes. Participants ran on a treadmill at 60% V̇o2max.nnnMAIN OUTCOME MEASURE(S)nu2003Rectal core temperature, heart rate, thermal comfort, perceived temperature, perceived wetness, and blood pressure.nnnRESULTSnu2003Average core temperature increased during 20 minutes of cooling (F1,28 = 64.76, P < .001, ηp2 = 0.70), regardless of group (F1,28 = 3.41, P = .08, ηp2 = 0.11) or condition (F1,28 < 1.0). Core temperature, heart rate, and blood pressure did not differ among the 3 conditions. Perceived temperature during 20 minutes of cooling decreased (F1,30 = 141.19, P < .001, ηp2 = 0.83) regardless of group or condition. Perceived temperature was lower with the mist-fan treatment than with the control treatment (F1,15 = 7.38, P = .02, ηp2 = 0.32). The mist-fan group perceived themselves to be cooler even at elevated core temperatures.nnnCONCLUSIONSnu2003The mist fan and cooling towel were both ineffective at lowering core temperature. Core temperature continued to increase after exercise in all groups. The mist fan produced feelings of coolness while the core temperature remained elevated, possibly increasing the risk of heat illness.