Core-temperature sensor ingestion timing and measurement variability

Context:

Telemetric core-temperature monitoring is becoming more widely used as a noninvasive means of monitoring core temperature during athletic events.

Objective:

To determine the effects of sensor ingestion timing on serial measures of core temperature during continuous exercise.

Design:

Crossover study.

Setting:

Outdoor dirt track at an average ambient temperature of 4.4°C ± 4.1°C and relative humidity of 74.1% ± 11.0%.

Patients or Other Participants:

Seven healthy, active participants (3 men, 4 women; age  =  27.0 ± 7.5 years, height  =  172.9 ± 6.8 cm, body mass  =  67.5 ± 6.1 kg, percentage body fat  =  12.7% ± 6.9%, peak oxygen uptake [V̇o_2peak]  =  54.4 ± 6.9 mL•kg⁻¹•min⁻¹) completed the study.

Intervention(s):

Participants completed a 45-minute exercise trial at approximately 70% V̇o_2peak. They consumed core-temperature sensors at 24 hours (P1) and 40 minutes (P2) before exercise.

Main Outcome Measure(s):

Core temperature was recorded continuously (1-minute intervals) using a wireless data logger worn by the participants. All data were analyzed using a 2-way repeated-measures analysis of variance (trial × time), Pearson product moment correlation, and Bland-Altman plot.

Results:

Fifteen comparisons were made between P1 and P2. The main effect of time indicated an increase in core temperature compared with the initial temperature. However, we did not find a main effect for trial or a trial × time interaction, indicating no differences in core temperature between the sensors (P1  =  38.3°C ± 0.2°C, P2  =  38.3°C ± 0.4°C).

Conclusions:

We found no differences in the temperature recordings between the 2 sensors. These results suggest that assumed sensor location (upper or lower gastrointestinal tract) does not appreciably alter the transmission of reliable and repeatable measures of core temperature during continuous running in the cold.     

Ankle strength and force sense after a progressive, 6-week strength-training program in people with functional ankle instability

Context:

Although strength training is commonly used to rehabilitate ankle injuries, studies investigating the effects of strength training on proprioception have shown conflicting results.

Objective:

To determine the effects of a 6-week strength-training protocol on force sense and strength development in participants with functional ankle instability.

Design:

Randomized controlled clinical trial.

Setting:

University athletic training research laboratory.

Patients or Other Participants:

A total of 40 participants with functional ankle instability were recruited. They were randomly placed into a training group (10 men, 10 women: age  =  20.9 ± 2.2 years, height  =  76.4 ± 16.1 cm, mass  =  173.0 ± 7.9 kg) or control group (10 men, 10 women: age  =  20.2 ± 2.1 years, height  =  78.8 ± 24.5 cm, mass  =  173.7 ± 8.2 kg).

Intervention(s):

Participants in the training group performed strength exercises with the injured ankle 3 times per week for 6 weeks. The protocol consisted of a combination of rubber exercise bands and the Multiaxial Ankle Exerciser, both clinically accepted strengthening methods for ankle rehabilitation. The progression of this protocol provided increasingly resistive exercise as participants changed either the number of sets or resistance of the Thera-Band or Multiaxial Ankle Exerciser.

Main Outcome Measure(s):

A load cell was used to measure strength and force sense. Inversion and eversion strength was recorded to the nearest 0.01 N. Force-sense reproduction was measured at 2 loads: 20% and 30% of maximal voluntary isometric contraction.

Results:

Increases in inversion (F_1,38  =  11.59, P < 0.01, η_p²  =  0.23, power  =  0.91) and eversion (F_1,38  =  57.68, P < .01, η_p²  =  0.60, power  =  0.99) strength were found in the training group at the posttest when compared with the control group. No significant improvements were noted in force-sense reproduction for either group.

Conclusions:

Strength training at the ankle increased strength but did not improve force sense.     

Tibiofemoral Joint Positioning for the Valgus Stress Test

Context:

Recommendations on the positioning of the tibiofemoral joint during a valgus stress test to optimize isolation of the medial collateral ligament (MCL) from other medial joint structures vary in the literature. If a specific amount of flexion could be identified as optimally isolating the MCL, teaching and using the technique would be more consistent in clinical application.

Objective:

To determine the angle of tibiofemoral joint flexion between 0° and 20° that causes a difference in the slope of the force-strain line when measuring the resistance to a valgus force applied to the joint.

Design:

Cross-sectional study.

Setting:

University research laboratory.

Patients or Other Participants:

Twelve healthy volunteers (6 men, 6 women: age  =  26.4 ± 5.6 years, height  =  170.9 ± 8.4 cm, mass  =  75.01 ± 14.6 kg).

Intervention(s):

Using an arthrometer, we applied a valgus force, over a range of 60 N, to the tibiofemoral joint in 0°, 5°, 10°, 15°, and 20° of flexion.

Main Outcome Measure(s):

Force-strain measurements were obtained for 5 positions of tibiofemoral joint flexion.

Results:

As knee flexion angle increased, slope values decreased (F_4,44  =  17.6, P < .001). The slope at full extension was not different from that at 5° of flexion, but it was different from the slopes at angles greater than 10° of flexion. Similarly, the slope at 5° of flexion was not different from that at 10° of flexion, but it was different from the slopes at 15° and 20° of flexion. Further, the slope at 10° of flexion was not different from that at 15° or 20° of flexion. Finally, the slope at 15° of flexion was not different from that at 20° of flexion.

Conclusions:

When performing the manual valgus stress test, the clinician should fully extend the tibiofemoral joint or flex it to 5° to assess all resisting medial tibiofemoral joint structures and again at 15° to 20° of joint flexion to further assess the MCL.     

Transcranial magnetic stimulation and volitional quadriceps activation

Context:

Quadriceps-activation deficits have been reported after meniscectomy. Transcranial magnetic stimulation (TMS) in conjunction with maximal contractions affects quadriceps activation in patients after meniscectomy.

Objective:

To determine the effect of single-pulsed TMS on quadriceps central activation ratio (CAR) in patients after meniscectomy.

Design:

Randomized controlled clinical trial.

Setting:

University laboratory.

Patients or Other Participants:

Twenty participants who had partial meniscectomy and who had a CAR less than 85% were assigned randomly to the TMS group (7 men, 4 women; age  =  38.1 ± 16.2 years, height  =  176.8 ± 11.5 cm, mass  =  91.8 ± 27.5 kg, postoperative time  =  36.7 ± 34.9 weeks) or the control group (7 men, 2 women; age  =  38.2 ± 17.5 years, height  =  176.5 ± 7.9 cm, mass  =  86.2 ± 15.3 kg, postoperative time  =  36.6 ± 37.4 weeks).

Intervention(s):

Participants in the experimental group received TMS over the motor cortex that was contralateral to the involved leg and performed 3 maximal quadriceps contractions with the involved leg. The control group performed 3 maximal quadriceps contractions without the TMS.

Main Outcome Measure(s):

Quadriceps activation was assessed using the CAR, which was measured in 70° of knee flexion at baseline and at 0, 10, 30, and 60 minutes posttest. The CAR was expressed as a percentage of full activation.

Results:

Differences in CAR were detected over time (F_4,72  =  3.025, P  = .02). No interaction (F_4,72  =  1.457, P  =  .22) or between-groups differences (F_1,18  =  0.096, P  =  .76) were found for CAR. Moderate CAR effect sizes were found at 10 (Cohen d  =  0.54, 95% confidence interval [CI]  =  −0.33, 1.37) and 60 (Cohen d  =  0.50, 95% CI  =  −0.37, 1.33) minutes in the TMS group compared with CAR at baseline. Strong effect sizes were found for CAR at 10 (Cohen d  =  0.82, 95% CI  =  −0.13, 1.7) and 60 (Cohen d  =  1.06, 95% CI  =  0.08, 1.95) minutes in the TMS group when comparing percentage change scores between groups.

Conclusions:

No differences in CAR were found between groups at selected points within a 60-minute time frame, yet moderate to strong effect sizes for CAR were found at 10 and 60 minutes in the TMS group, indicating increased activation after TMS.     

Emergency face-mask removal effectiveness: a comparison of traditional and nontraditional football helmet face-mask attachment systems

Context:

Football helmet face-mask attachment design changes might affect the effectiveness of face-mask removal.

Objective:

To compare the efficiency of face-mask removal between newly designed and traditional football helmets.

Design:

Controlled laboratory study.

Setting:

Applied biomechanics laboratory.

Participants:

Twenty-five certified athletic trainers.

Intervention(s):

The independent variable was face-mask attachment system on 5 levels: (1) Revolution IQ with Quick Release (QR), (2) Revolution IQ with Quick Release hardware altered (QRAlt), (3) traditional (Trad), (4) traditional with hardware altered (TradAlt), and (5) ION 4D (ION). Participants removed face masks using a cordless screwdriver with a back-up cutting tool or only the cutting tool for the ION. Investigators altered face-mask hardware to unexpectedly challenge participants during removal for traditional and Revolution IQ helmets. Participants completed each condition twice in random order and were blinded to hardware alteration.

Main Outcome Measure(s):

Removal success, removal time, helmet motion, and rating of perceived exertion (RPE). Time and 3-dimensional helmet motion were recorded. If the face mask remained attached at 3 minutes, the trial was categorized as unsuccessful. Participants rated each trial for level of difficulty (RPE). We used repeated-measures analyses of variance (α  =  .05) with follow-up comparisons to test for differences.

Results:

Removal success was 100% (48 of 48) for QR, Trad, and ION; 97.9% (47 of 48) for TradAlt; and 72.9% (35 of 48) for QRAlt. Differences in time for face-mask removal were detected (F_4,20  =  48.87, P  =  .001), with times ranging from 33.96 ± 14.14 seconds for QR to 99.22 ± 20.53 seconds for QRAlt. Differences were found in range of motion during face-mask removal (F_4,20  =  16.25, P  =  .001), with range of motion from 10.10° ± 3.07° for QR to 16.91° ± 5.36° for TradAlt. Differences also were detected in RPE during face-mask removal (F_4,20  =  43.20, P  =  .001), with participants reporting average perceived difficulty ranging from 1.44 ± 1.19 for QR to 3.68 ± 1.70 for TradAlt.

Conclusions:

The QR and Trad trials resulted in superior results. When trials required cutting loop straps, results deteriorated.     

Cooling the neck region during exercise in the heat

Context:

Cooling the neck region can improve the ability to exercise in a hot environment. It might improve performance by dampening the perceived level of thermal strain, allowing individuals to override inhibitory signals.

Objective:

To investigate whether the enhanced ability to exercise in a hot environment observed when cooling the neck region occurs because of dampening the perceived level of thermal strain experienced and the subsequent overriding of inhibitory signals.

Design:

Crossover study.

Setting:

Walk-in environmental chamber.

Patients or Other Participants:

Eight endurance-trained, nonacclimated men (age  =  26 ± 2 years, height  =  1.79 ± 0.04 m, mass  =  77.0 ± 6.2 kg, maximal oxygen uptake [V̇O_2max]  =  56.2 ± 9.2 mL·kg⁻¹·min⁻¹) participated.

Intervention(s):

Participants completed 4 running tests at approximately 70% V̇O_2max to volitional exhaustion: 2 familiarization trials followed by 2 experimental trials (cooling collar [CC] and no collar [NC]). Trials were separated by 7 days. Familiarization and NC trials were performed without a collar and used to assess the test variability.

Main Outcome Measure(s):

Time to volitional exhaustion, heart rate, rectal temperature, neck skin temperature, rating of perceived exertion, thermal sensation, and feeling scale (pleasure/displeasure) were measured.

Results:

Time to volitional exhaustion was increased by 13.5% ± 3.8% (CC  =  43.15 ± 12.82 minutes, NC  =  38.20 ± 11.70 minutes; t₇  =  9.923, P < .001) with the CC, which reduced mean neck skin temperature throughout the test (P < .001). Participants terminated exercise at identical levels of perceived exertion, thermal sensation, and feeling scale, but the CC enabled participants to tolerate higher rectal temperatures (CC  =  39.61°C ± 0.45°C, NC  =  39.18°C ± 0.7°C; t₇  =  −3.217, P  =  .02) and heart rates (CC  =  181 ± 6 beats/min, NC  =  178 ± 9 beats/min; t₇  =  −2.664, P  =  .03) at the point of termination.

Conclusions:

Cooling the neck increased the time taken to reach volitional exhaustion by dampening the perceived levels of thermal strain.     

Sweat Rates, Sweat Sodium Concentrations, and Sodium Losses in 3 Groups of Professional Football Players

Context:

Sweat sodium losses have never been reported in a large cohort of American football players.

Objective:

To compare sweat rates (SwtRs), sweat sodium concentrations (SwtNa⁺), and sodium losses in 3 groups of players (backs and receivers [BK], linebackers and quarterbacks [LB/QB], and linemen [LM]) to determine if positional differences and, therefore, size differences exist.

Design:

Observational study.

Setting:

Data were collected during practices in the second week of 2 consecutive training camps. The wet bulb globe temperature was 78.5°F ± 3.5°F (25.9°C ± 1.9°C).

Patients or Other Participants:

Eighteen BK, 12 LB/QB, and 14 LM volunteered.

Intervention(s):

Sterile sweat patches were applied to the right forearm after the skin was appropriately cleaned. The patches were removed during practice, placed in sterile tubes, centrifuged, frozen, and later analyzed by flame photometry.

Main Outcome Measure(s):

Sweat rate, SwtNa⁺, and sodium loss. We calculated SwtR by change in mass adjusted for urine produced and fluids consumed divided by practice time in hours.

Results:

Other than age, physical characteristics were different among groups (P < .001). The SwtR was different among groups (F_2,41  =  7.3, P  =  .002). It was lower in BK (1.42 ± 0.45 L/h) than in LB/QB (1.98 ± 0.49 L/h) (P < .05) and LM (2.16 ± 0.75 L/h) (P < .01), but we found no differences between SwtRs for LB/QB and LM. The SwtNa⁺ was not different among groups (BK  =  50 ± 16 mEq/L, LB/QB  =  48.2 ± 23 mEq/L, and LM  =  52.8 ± 25 mEq/L) and ranged from 15 to 99 mEq/L. Sweat sodium losses ranged from 642 mg/h to 6.7 g/h, and findings for group comparisons approached significance (P  =  .06). On days when players practiced 4.5 hours, calculated sodium losses ranged from 2.3 to 30 g/d.

Conclusions:

The BK sweated at lower rates than did the midsized LB/QB and large LM, but LB/QB sweated similarly to LM. Sweat sodium concentration and daily sodium losses ranged considerably. Heavy, salty sweaters require increased dietary consumption of sodium during preseason.     

Cold-Water Immersion and the Treatment of Hyperthermia: Using 38.6��C as a Safe Rectal Temperature Cooling Limit

Context:

Cold-water immersion is recommended for the immediate field treatment of exertional heat stroke. However, concerns exist over potential overcooling of hyperthermic individuals during cold-water immersion.

Objective:

To evaluate the recommendation that removing previously hyperthermic individuals from a cold-water bath at a rectal temperature (T_re) of 38.6°C would attenuate overcooling.

Design:

Controlled laboratory study.

Setting:

University research laboratory.

Patients or Other Participants:

Participants included 6 men and 4 women (age  =  22 ± 3 years, height  =  172 ± 10 cm, mass  =  67.8 ± 10.7 kg, body fat percentage  =  17.1% ± 4.5%, maximum oxygen consumption  =  59.3 ± 8.7 mL·kg⁻¹·min⁻¹).

Intervention(s):

After exercising at an ambient temperature of 40.0°C for 38.5 ± 9.4 minutes, until T_re reached 39.5°C, participants were immersed in a 2.0°C circulated water bath until T_re decreased to either 37.5°C or 38.6°C. Subsequently, participants were removed from the water bath and recovered for 20 minutes at an ambient temperature of 25°C.

Main Outcome Measure(s):

Rectal and esophageal temperatures were measured continuously during the immersion and recovery periods.

Results:

Because of the experimental design, the overall time of immersion was greater during the 37.5°C trial (16.6 ± 5.7 minutes) than the 38.6°C trial (8.8 ± 2.6 minutes) (t₉  =  −4.740, P  =  .001). During the recovery period after cold-water immersion, both rectal (F_1,9  =  50.540, P < .001) and esophageal (F_1,6  =  20.365, P  =  .007) temperatures remained greater in the 38.6°C trial than in the 37.5°C trial. This was evidenced by low points of 36.47°C ± 0.70°C and 37.19°C ± 0.71°C for rectal temperature (t₉  =  2.975, P  =  .016) and of 35.67°C ± 1.27°C and 36.72°C ± 0.95°C for esophageal temperature (t₆  =  3.963, P  =  .007) during the recovery period of the 37.5°C and 38.6°C trials, respectively.

Conclusions:

Immersion for approximately 9 minutes to a rectal temperature cooling limit of 38.6°C negated any risk associated with overcooling hyperthermic individuals when they were immersed in 2°C water.     

Hydration behaviors before and after an educational and prescribed hydration intervention in adolescent athletes

Context:

The effectiveness of education in modifying hydration behaviors in adolescent athletes is unclear.

Objective:

To assess the hydration status and behaviors of female athletes before and after a 1-time educational intervention and prescribed hydration intervention in a warm, humid, tropical environment.

Design:

Cohort study.

Setting:

Non–air-conditioned gymnasium in a tropical environment (indoor wet bulb globe temperature  =  24.0 ± 0.2°C).

Patient or Other Participants:

Thirty-six female adolescent elite volleyball players (age  =  14.8 ± 0.8 years, height  =  168.2 ± 8.2 cm, mass  =  60.8 ± 9.0 kg, body mass index  =  21.7 ± 2.7, body surface area  =  1.65 ± 0.14 m², body surface area to mass ratio  =  2.71 ± 0.18 m²·kg⁻¹·10⁻²) participated.

Intervention(s):

Four observational periods consisting of 3 practices per observational period separated by 48 hours. The 4 periods included a control period, educational intervention, prescribed hydration intervention (PHI), and observational follow-up (OF-U). After the control period, an educational intervention consisting of a slide presentation was provided to the participants, followed by a week of observation. In the PHI, a precalculated volume of water based on individual sweat rate was consumed every 20 minutes during each 2-hour practice. During all other periods, participants consumed their fluid of choice ad libitum. The order of the treatment periods was not randomized and was the same for all participants.

Main Outcome Measure(s):

Prepractice to postpractice changes in body mass (ΔBM), percentage of body mass lost (%BML), urine specific gravity, urine color, urine osmolality, sweat rate, and volume of fluid consumed (F_vol).

Results:

The PHI was the only period during which participants maintained body mass (ΔBM  =  0.05 ± 1.3%); F_vol consumed was greatest during this time (F_vol  =  1.3 ± 0.4 L; F_1,3  =  34.869, P ≤ .001). The ΔBM was less for the PHI (ΔBM  =  0.05 ± 0.9 kg, %BML  =  0.04 ± 1.3%) than the OF-U period (ΔBM  =  −0.7 ± 1.1 kg, %BML  =  −1.2 ± 1.9%; F_1,3  =  6.220, P  =  .01). The F_vol (1.3 ± 0.4 L) and percentage of fluid consumed (143.7 ± 110.8%) to restore sweat loss for the PHI period were higher than for any other period (F_1,3  =  34.869, P ≤ .001). None of the participants experienced serious dehydration in any of the conditions.

Conclusions:

A 1-time education session alone was not successful in changing hydration behaviors. However, prescribing individualized hydration protocols improved hydration for adolescents exercising in a warm, humid environment.     

Contribution of Knee Flexor and Extensor Strength on Sex-Specific Energy Absorption and Torsional Joint Stiffness During Drop Jumping

Context:

Lower extremity injury often occurs during abrupt deceleration when attempting to change the body''s direction. Although sex-specific biomechanics have been implicated in the greater risk of acute knee injury in women than in men, it is unknown if sex differences in thigh strength affect sex-specific energy absorption and torsional joint stiffness patterns.

Objective:

To determine sex differences in energy absorption patterns and joint stiffnesses of the lower extremity during a drop jump and to determine if these sex differences were predicted by knee extensor and flexor strength.

Design:

Cross-sectional study.

Setting:

Laboratory environment.

Patients or Other Participants:

Recreationally active, college-aged students (41 women: age  =  22.1 ± 2.9 years, height  =  1.63 ± 0.07 m, mass  =  59.3 ± 8.0 kg; 40 men: age  =  22.4 ± 2.8 years, height  =  1.77 ± 0.1 m, mass  =  80.9 ± 14.1 kg).

Intervention(s):

Participants performed knee flexor and extensor maximal voluntary isometric contractions followed by double-leg drop-jump landings.

Main Outcome Measure(s):

Lower extremity joint energetics (J × N⁻¹ × m⁻¹) and torsional joint stiffnesses (Nm × N⁻¹ × m⁻¹ × degrees⁻¹) were calculated for the hip, knee, and ankle during the initial landing phase. Body weight was measured in newtons and height was measured in meters. Sex comparisons were made and sex-specific regressions determined if thigh muscle strength (Nm/kg) predicted sagittal-plane landing energetics and stiffnesses.

Results:

Women absorbed 69% more knee energy and had 36% less hip torsional stiffness than men. In women, greater knee extensor strength predicted greater knee energy absorption (R²  =  0.11, P  =  .04), and greater knee flexor strength predicted greater hip torsional stiffness (R²  =  0.12, P  =  .03).

Conclusions:

Sex-specific biomechanics during the deceleration phase of a drop jump revealed that women used a strategy to attempt to decrease system stiffness. Additionally, only female strength values were predictive of landing energetics and stiffnesses. These findings collectively demonstrated that the task may have been more difficult for women, resulting in a different movement strategy among those with different levels of thigh strength to safely complete the task. Future researchers should look at other predictive factors of observed sex differences.     

Balance performance with a cognitive task: a continuation of the dual-task testing paradigm

Context:

To ensure that concussed athletes return to play safely, we need better methods of measuring concussion severity and monitoring concussion resolution.

Objective:

To develop a dual-task model that assesses postural stability and cognitive processing in concussed athletes.

Design:

Repeated measures study.

Setting:

University laboratory.

Patients or Other Participants:

Twenty healthy, college-aged students (10 men, 10 women; age  =  20 ± 1.86 years, height  =  173 ± 4.10 cm, mass  =  71.83 + 35.77 kg).

Intervention(s):

Participants were tested individually in 2 sessions separated by 2 days. In one session, a balance task and a cognitive task were performed separately. In the other session, the balance and cognitive tasks were performed concurrently. The balance task consisted of 6 conditions of the Sensory Organization Test performed on the NeuroCom Smart Balance Master. The cognitive task consisted of an auditory switch task (3 trials per condition, 60 seconds per trial).

Main Outcome Measure(s):

For the balance test, scores for each Sensory Organization Test condition; the visual, vestibular, somatosensory, and visual-conflict subscores; and the composite balance score were calculated. For the cognitive task, response time and accuracy were measured.

Results:

Balance improved during 2 dual-task conditions: fixed support and fixed visual reference (t₁₈  =  −2.34, P < .05) and fixed support and sway visual reference (t₁₈  =  −2.72, P  =  .014). Participants'' response times were longer (F_1,18  =  67.77, P < .001, η²  =  0.79) and choice errors were more numerous under dual-task conditions than under single-task conditions (F_1,18  =  5.58, P  =  .03, η²  =  0.24). However, differences were observed only during category-switch trials.

Conclusions:

Balance was either maintained or improved under dual-task conditions. Thus, postural control took priority over cognitive processing when the tasks were performed concurrently. Furthermore, dual-task conditions can isolate specific mental processes that may be useful for evaluating concussed individuals.     

Retest Reliability of Force-Time Variables of Neck Muscles Under Isometric Conditions

Context:

Proper conditioning of the neck muscles may play a role in reducing the risk of neck injury and, possibly, concussions in contact sports. However, the ability to reliably measure the force-time–based variables that might be relevant for this purpose has not been addressed.

Objective:

To assess the between-days reliability of discrete force-time–based variables of neck muscles during maximal voluntary isometric contractions in 5 directions.

Design:

Cohort study.

Setting:

University research center.

Patients or Other Participants:

Twenty-six highly physically active men (age  =  21.6 ± 2.1 years, height  =  1.85 ± 0.09 m, mass  =  81.6 ± 9.9 kg, head circumference  =  0.58 ± 0.01 m, neck circumference  =  0.39 ± 0.02 m).

Intervention(s):

We used a custom-built testing apparatus to measure maximal voluntary isometric contractions of the neck muscles in 5 directions (extension, flexion, protraction, left lateral bending, and right lateral bending) on 2 separate occasions separated by 7 to 8 days.

Main Outcome Measure(s):

Variables measured were peak force (PF), rate of force development (RFD), and time to 50% of PF (T₅₀PF). Reliability indices calculated for each variable comprised the difference in scores between the testing sessions, with corresponding 95% confidence intervals, the coefficient of variation of the typical error of measurement (CV_TE), and intraclass correlation coefficients (ICC [3,3]).

Results:

No evidence of systematic bias was detected for the dependent measures across any movement direction; retest differences in measurements were between 1.8% and 2.7%, with corresponding 95% confidence interval ranges of less than 10% and overlapping zero. The CV_TE was lowest for PF (range, 2.4%–6.3%) across all testing directions, followed by RFD (range, 4.8%–9.0%) and T₅₀PF (range, 7.1%–9.3%). The ICC score range for all dependent measures was 0.90 to 0.99.

Conclusions:

Discrete variables representative of the force-generating capacity of neck muscles under isometric conditions can be measured with an acceptable degree of reliability. This finding has possible applications for investigating the role of neck muscle strength-training programs in reducing the risk of injuries in sport settings.     

Glenohumeral rotational motion and strength and baseball pitching biomechanics

Context:

Addressing loss of shoulder range of motion and rotator cuff weakness in injury-prevention programs might be an effective strategy for preventing throwing arm injuries in baseball pitchers. However, the influence of these clinical measures on pitching biomechanics is unclear.

Objective:

To evaluate the relationships among clinical measures of shoulder rotational motion and strength and 3-dimensional pitching biomechanics and to evaluate the presence of coupling between the shoulder and the elbow during pitching to provide insight into the influence of clinical shoulder characteristics on elbow biomechanics.

Design:

Cross-sectional study.

Setting:

Biomechanics laboratory.

Patients or Other Participants:

A total of 27 uninjured male high school baseball pitchers (age  =  16 ± 1.1 years, height  =  183 ± 7 cm, mass  =  83 ± 12 kg).

Main Outcome Measure(s):

Clinical measures included shoulder internal- and external-rotation range of motion and peak isometric internal- and external-rotator strength. Three-dimensional upper extremity biomechanics were assessed as participants threw from an indoor pitching mound to a target at regulation distance. Linear regressions were used to assess the influence of clinical measures on the peak shoulder internal and external rotation moments and the peak elbow-adduction moment.

Results:

We found a positive relationship between clinically measured internal-rotator strength and shoulder external-rotation moment (R²  =  0.181, P  =  .04) during pitching. We also noted an inverse relationship between clinically measured external-rotation motion and the elbow-adduction moment (R²  =  0.160, P  =  .04) and shoulder internal-rotation moment (R²  =  0.250, P  =  .008) during pitching. We found a positive relationship between peak shoulder internal-rotation moment and the peak elbow-adduction moment (R²  =  0.815, P < .001) during pitching.

Conclusions:

This study provides insight into the effects of shoulder strength and motion on pitching biomechanics and how these clinical measures might contribute to throwing arm injuries in the baseball pitcher. A relationship also was identified between peak shoulder and elbow moments in the throwing arm during pitching, providing biomechanical support for addressing clinical shoulder characteristics as a potential strategy for preventing elbow injury.     

Lacrosse Equipment and Cervical Spinal Cord Space During Immobilization: Preliminary Analysis

Context:

Removal of the lacrosse helmet to achieve airway access has been discouraged based only on research in which cervical alignment was examined. No researchers have examined the effect of lacrosse equipment on the cervical space available for the spinal cord (SAC).

Objective:

To determine the effect of lacrosse equipment on the cervical SAC and cervical-thoracic angle (CTA) in the immobilized athlete.

Design:

Observational study.

Setting:

Outpatient imaging center.

Patients or Other Participants:

Ten volunteer lacrosse athletes (age  =  20.7 ± 1.87 years, height  =  180.3 ± 8.3 cm, mass  =  91 ± 12.8 kg) with no history of cervical spine injury or disease and no contraindications to magnetic resonance imaging (MRI).

Intervention(s):

The lacrosse players were positioned supine on a spine board for all test conditions. An MRI scan was completed for each condition.

Main Outcome Measure(s):

The independent variables were condition (no equipment, shoulder pads only [SP], and full gear that included helmet and shoulder pads [FG]), and cervical spine level (C3–C7). The dependent variables were the SAC and CTA. The MRI scans were evaluated midsagittally. The average of 3 measures was used as the criterion variable. The SAC data were analyzed using a 3 × 5 analysis of variance (ANOVA) with repeated measures. The CTA data were analyzed with a 1-way repeated-measures ANOVA.

Results:

We found no equipment × level interaction effect (F_3.7,72  =  1.34, P  =  .279) or equipment main effect (F_2,18  =  1.20, P  =  .325) for the SAC (no equipment  =  5.04 ± 1.44 mm, SP  =  4.69 ± 1.36 mm, FG  =  4.62 ± 1.38 mm). The CTA was greater (ie, more extension; critical P  =  .0167) during the SP (32.64° ± 3.9°) condition than during the no-equipment (25.34° ± 2.3°; t₉  =  7.67, P  =  .001) or FG (26.81° ± 5.1°; t₉  =  4.80, P  =  .001) condition.

Conclusions:

Immobilizing healthy lacrosse athletes with shoulder pads and no helmets affected cervical spine alignment but did not affect SAC. Further research is needed to determine and identify appropriate care of the lacrosse athlete with a spine injury.     

Gastric emptying after pickle-juice ingestion in rested, euhydrated humans

Context:

Small volumes of pickle juice (PJ) relieve muscle cramps within 85 seconds of ingestion without significantly affecting plasma variables. This effect may be neurologic rather than metabolic. Understanding PJ''s gastric emptying would help to strengthen this theory.

Objective:

To compare gastric emptying and plasma variables after PJ and deionized water (DIW) ingestion.

Design:

Crossover study.

Setting:

Laboratory.

Patients or Other Participants:

Ten men (age  =  25.4 ± 0.7 years, height  =  177.1 ± 1.6 cm, mass  =  78.1 ± 3.6 kg).

Intervention(s):

Rested, euhydrated, and eunatremic participants ingested 7 mL·kg⁻¹ body mass of PJ or DIW on separate days.

Main Outcome Measure(s):

Gastric volume was measured at 0, 5, 10, 20, and 30 minutes postingestion (using the phenol red dilution technique). Percentage changes in plasma volume and plasma sodium concentration were measured preingestion (−45 minutes) and at 5, 10, 20, and 30 minutes postingestion.

Results:

Initial gastric volume was 624.5 ± 27.4 mL for PJ and 659.5 ± 43.8 mL for DIW (P > .05). Both fluids began to empty within the first 5 minutes (volume emptied: PJ  =  219.2 ± 39.1 mL, DIW  =  305.0 ± 40.5 mL, P < .05). Participants who ingested PJ did not empty further after the first 5 minutes (P > .05), whereas in those who ingested DIW, gastric volume decreased to 111.6 ± 39.9 mL by 30 minutes (P < .05). The DIW group emptied faster than the PJ group between 20 and 30 minutes postingestion (P < .05). Within 5 minutes of PJ ingestion, plasma volume decreased 4.8% ± 1.6%, whereas plasma sodium concentration increased 1.6 ± 0.5 mmol·L⁻¹ (P < .05). Similar changes occurred after DIW ingestion. Calculated plasma sodium content was unchanged for both fluids (P > .05).

Conclusions:

The initial decrease in gastric volume with both fluids is likely attributable to gastric distension. Failure of the PJ group to empty afterward is likely due to PJ''s osmolality and acidity. Cardiovascular reflexes resulting from gastric distension are likely responsible for the plasma volume shift and rise in plasma sodium concentration despite nonsignificant changes in plasma sodium content. These data support our theory that PJ does not relieve cramps via a metabolic mechanism.     

Age-Related Differences and Reliability on Computerized and Paper-and-Pencil Neurocognitive Assessment Batteries

Context:

Neurocognitive testing is a recommended component in a concussion assessment. Clinicians should be aware of age and practice effects on these measures to ensure appropriate understanding of results.

Objective:

To assess age and practice effects on computerized and paper-and-pencil neurocognitive testing batteries in collegiate and high school athletes.

Design:

Cohort study.

Setting:

Classroom and laboratory.

Patients or Other Participants:

Participants consisted of 20 collegiate student-athletes (age  =  20.00 ± 0.79 years) and 20 high school student-athletes (age  =  16.00 ± 0.86 years).

Main Outcome Measure(s):

Hopkins Verbal Learning Test scores, Brief Visual-Spatial Memory Test scores, Trail Making Test B total time, Symbol Digit Modalities Test score, Stroop Test total score, and 5 composite scores from the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) served as outcome measures. Mixed-model analyses of variance were used to examine each measure.

Results:

Collegiate student-athletes performed better than high school student-athletes on ImPACT processing speed composite score (F_1,38  =  5.03, P  =  .031) at all time points. No other age effects were observed. The Trail Making Test B total time (F_2,66  =  73.432, P < .001), Stroop Test total score (F_2,76  =  96.85, P  =  < .001) and ImPACT processing speed composite score (F_2,76  =  5.81, P  =  .005) improved in test sessions 2 and 3 compared with test session 1. Intraclass correlation coefficient calculations demonstrated values ranging from 0.12 to 0.72.

Conclusions:

An athlete''s neurocognitive performance may vary across sessions. It is important for clinicians to know the reliability and precision of these tests in order to properly interpret test scores.     

Correlation between central corneal thickness and intraocular pressure peak and fluctuation during the water drinking test in glaucoma patients

OBJECTIVE:

To investigate the correlation between central corneal thickness and outflow facility assessed by intraocular pressure peak and fluctuation during the water drinking test.

METHODS:

Fifty‐five newly diagnosed primary open‐angle glaucoma patients submitted to central corneal thickness measurements and water drinking test were enrolled in this retrospective study.;. Patients were divided into three groups according to their central corneal thickness. Pearson''s Correlation test was performed in the groups with lower and higher pachymetric values.

RESULTS:

The mean age was 65,65 ± 28,28 years; 63,63% were female and 52,72% were caucasian. The mean central corneal thickness was 544,32 ± 36,86 µm, and the mean baseline intraocular pressure was 23,36 ± 6,26 mmHg. During the water drinking test, the mean intraocular pressure peak and mean intraocular pressure fluctuation were 30,43 ± 8,13 mmHg and 31,46 ± 18,46%, respectively. No relevant correlation was detected between the central corneal thickness and the intraocular pressure peak (r² = 0,021) or between the central corneal thickness and the intraocular pressure fluctuation (r² = 0,011). Group 1 presented a mean central corneal thickness of 505,81 ± 13,86 µm, and Group 3 was 583,55 ± 27,87 µm (p = 0,001). The mean intraocular pressure peak was 31,05 ± 9,05 mmHg and 27,83 ± 4,92 mmHg in Group 1 and in Group 3, respectively (p = 0,193). The difference of intraocular pressure fluctuation was not statistically significant between Group 1 (mean 28,47 ± 16,25%) and Group 3 (mean 33,27 ± 21,27%) (p = 0,43).

CONCLUSION:

In our case series, no correlation was found between central corneal thickness and water drinking test results.