Short-term diabetes attenuates left ventricular dysfunction and mortality rates after myocardial infarction in rodents

OBJECTIVES:

To investigate the effects of hyperglycemia on left ventricular dysfunction, morphometry, myocardial infarction area, hemodynamic parameters, oxidative stress profile, and mortality rate in rats that had undergone seven days of myocardial infarction.

INTRODUCTION:

Previous research has demonstrated that hyperglycemia may protect the heart against ischemic injury.

METHODS:

Male Wistar rats were divided into four groups: control-sham, diabetes-sham, myocardial infarction, and diabetes + myocardial infarction. Myocardial infarction was induced 14 days after diabetes induction. Ventricular function and morphometry, as well as oxidative stress and hemodynamic parameters, were evaluated after seven days of myocardial infarction.

RESULTS:

The myocardial infarction area, which was similar in the infarcted groups at the initial evaluation, was reduced in the diabetes + myocardial infarction animals (23±3%) when compared with the myocardial infarction (42±7%, p<0.001) animals at the final evaluation. The ejection fraction (22%, p = 0.003), velocity of circumferential fiber shortening (30%, p = 0.001), and left ventricular isovolumetric relaxation time (26%, p = 0.002) were increased in the diabetes + myocardial infarction group compared with the myocardial infarction group. The diabetes-sham and diabetes + myocardial infarction groups displayed increased catalase concentrations compared to the control-sham and myocardial infarction groups (diabetes-sham: 32±3; diabetes + myocardial infarction: 35±0.7; control-sham: 12±2; myocardial infarction: 16±0.1 pmol min^-1 mg^-1 protein). The levels of thiobarbituric acid-reactive substances were reduced in the diabetes-sham rats compared to the control-sham rats. These positive adaptations were reflected in a reduced mortality rate in the diabetes + myocardial infarction animals (18.5%) compared with the myocardial infarction animals (40.7%, p = 0.001).

CONCLUSIONS:

These data suggest that short-term hyperglycemia initiates compensatory mechanisms, as demonstrated by increased catalase levels, which culminate in improvements in the ventricular response, infarcted area, and mortality rate in diabetic rats exposed to ischemic injury.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Influence of perineal prostatectomy on anal continence

OBJECTIVE:

Perineal prostatectomy has been proposed as a less invasive and safe procedure, but the risk of anal incontinence has been studied. This study aimed to evaluate the effects of perineal access on anal continence mechanisms after perineal prostatectomy.

METHODS:

From August 2008 to May 2009, twenty three patients underwent perineal prostatectomy. These patients were evaluated before surgery and eight months postoperatively using the Cleveland Clinic Anal Incontinence Score, the Fecal Incontinence Quality of Life Score, and anorectal manometry.

RESULTS:

The mean age of the subjects was 65 (range, 54-72) years, and the mean prostate weight was 34.5 (range, 24-54) grams. Gleason scores ranged from 6-7, and the mean Cleveland Clinic Anal Incontinence Score (mean±standard deviation) values were 0.9±1.9 and 0.7±1.2 (p>0.05) before and after surgery, respectively. The Fecal Incontinence Quality of Life Score did not change significantly after surgery. The mean values for anal manometric parameters before and after surgery were, respectively: Resting Pressures of 64±23 mmHg and 65±17 mmHg (p = 0.763), Maximum Squeezing Pressures of 130±41 mmHg and 117±40 mmHg (p = 0.259), High Pressure Zones of 3.0±0.9 cm and 2.7±0.8 cm (p = 0.398), Rectal Sensory Thresholds of 76±25 ml and 71±35 ml (p = 0.539), Maximum Tolerated Rectal Volumes of 157±48 ml and 156±56 ml (p = 0.836), and Sphincter Asymmetry Indexes 22.4±9% and 14.4±5% (p = 0.003).

CONCLUSION:

There was a significant decrease in the sphincter symmetry index after perineal prostatectomy. With the exception of the sphincter asymmetry index, perineal prostatectomy did not affect anal continence parameters.     

Cardiovascular and autonomic responses after exercise sessions with different intensities and durations

BACKGROUND:

Several studies have reported the phenomenon of post-exercise hypotension. However, the factors that cause this drop in blood pressure after a single exercise session are still unknown.

OBJECTIVE:

To investigate the effects of aerobic exercise on the acute blood pressure response and to investigate the indicators of autonomic activity after exercise.

METHODS:

Ten male subjects (aged 25 ± 1 years) underwent four experimental exercise sessions and a control session on a cycle ergometer. The blood pressure and heart rate variability of each subject were measured at rest and at 60 min after the end of the sessions.

RESULTS:

Post-exercise hypotension was not observed in any experimental sessions (P > 0.05). The index of parasympathetic neural activity, the RMSSD, only remained lower than that during the pre-exercise session after the high-intensity session (Δ  = -19 ± 3.7 for 15-20 min post-exercise). In addition, this value varied significantly (P < 0.05) between the high- and low-intensity sessions (Δ  =  -30.7 ± 4.0 for the high intensity session, and Δ  =  -9.9 ± 2.5 for the low intensity session).

CONCLUSION:

The present study did not find a reduction in blood pressure after exercise in normotensive, physically active young adults. However, the measurements of the indicators of autonomic neural activity revealed that in exercise of greater intensity the parasympathetic recovery tends to be slower and that sympathetic withdrawal can apparently compensate for this delay in recovery.     

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.     

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.     

Endothelial and Non-Endothelial Coronary Blood Flow Reserve and Left Ventricular Dysfunction in Systemic Hypertension

OBJECTIVES:

We evaluated the impairment of endothelium-dependent and endothelium-independent coronary blood flow reserve after administration of intracoronary acetylcholine and adenosine, and its association with hypertensive cardiac disease.

INTRODUCTION:

Coronary blood flow reserve reduction has been proposed as a mechanism for the progression of compensated left ventricular hypertrophy to ventricular dysfunction.

METHODS:

Eighteen hypertensive patients with normal epicardial coronary arteries on angiography were divided into two groups according to left ventricular fractional shortening (FS). Group 1 (FS ≥0.25): n=8, FS=0.29 ± 0.03; Group 2 (FS <0.25): n=10, FS= 0.17 ± 0.03.

RESULTS:

Baseline coronary blood flow was similar in both groups (Group 1: 80.15 ± 26.41 mL/min, Group 2: 100.09 ± 21.51 mL/min, p=NS). In response to adenosine, coronary blood flow increased to 265.1 ± 100.2 mL/min in Group 1 and to 300.8 ± 113.6 mL/min (p <0.05) in Group 2. Endothelium-independent coronary blood flow reserve was similar in both groups (Group 1: 3.31 ± 0.68 and Group 2: 2.97 ± 0.80, p=NS). In response to acetylcholine, coronary blood flow increased to 156.08 ± 36.79 mL/min in Group 1 and to 177.8 ± 83.6 mL/min in Group 2 (p <0.05). Endothelium-dependent coronary blood flow reserve was similar in the two groups (Group 1: 2.08 ± 0.74 and group Group 2: 1.76 ± 0.61, p=NS). Peak acetylcholine/peak adenosine coronary blood flow response (Group 1: 0.65 ± 0.27 and Group 2: 0.60 ± 0.17) and minimal coronary vascular resistance (Group 1: 0.48 ± 0.21 mmHg/mL/min and Group 2: 0.34 ± 0.12 mmHg/mL/min) were similar in both groups (p= NS). Casual diastolic blood pressure and end-systolic left ventricular stress were independently associated with FS.

CONCLUSIONS:

In our hypertensive patients, endothelium-dependent and endothelium-independent coronary blood flow reserve vasodilator administrations had similar effects in patients with either normal or decreased left ventricular systolic function.     

Interday reliability of peak muscular power outputs on an isotonic dynamometer and assessment of active trunk control using the chop and lift tests

Context:

Assessment techniques used to measure functional tasks involving active trunk control are restricted to linear movements that lack the explosive movements and dynamic tasks associated with activities of daily living and sport. Reliable clinical methods used to assess the diagonal and ballistic movements about the trunk are lacking.

Objective:

To assess the interday reliability of peak muscular power outputs while participants performed diagonal chop and lift tests and maintained a stable trunk.

Design:

Controlled laboratory study.

Setting:

University research laboratory.

Patients or Other Participants:

Eighteen healthy individuals (10 men and 8 women; age  =  32 ± 11 years, height  =  168 ± 12 cm, mass  =  80 ± 19 kg) from the general population participated.

Intervention(s):

Participants performed 2 power tests (chop, lift) using an isotonic dynamometer and 3 endurance tests (Biering-Sørensen, side-plank left, side-plank right) to assess active trunk control. Testing was performed on 3 different days separated by at least 1 week. Reliability was compared between days 1 and 2 and between days 2 and 3. Correlations between the power and endurance tests were evaluated to determine the degree of similarity.

Main Outcome Measure(s):

Peak muscular power outputs (watts) derived from a 1-repetition maximum protocol for the chop and lift tests were collected for both the right and left sides.

Results:

Intraclass correlation coefficients for peak muscular power were highly reliable for the chop (range, 0.87–0.98), lift (range, 0.83–0.96), and endurance (range, 0.80–0.98) tests between test sessions. The correlations between the power assessments and the Biering-Sørensen test (r range, −0.008 to 0.017) were low. The side-plank tests were moderately correlated with the chop (r range, 0.528–0.590) and the lift (r range, 0.359–0.467) tests.

Conclusions:

The diagonal chop and lift power protocol generated reliable data and appears to be a dynamic test that simulates functional tasks, which require dynamic trunk control.     

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.     

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.     

Ankle Bracing and the Neuromuscular Factors Influencing Joint Stiffness

Context:

Health care professionals commonly prescribe external stabilization to decrease the incidence and severity of ankle sprains. The mechanism for this decrease is not clearly understood. Examining the effects of ankle bracing on biomechanical stability and influencing factors may provide important information regarding the neuromuscular effects of bracing.

Objective:

To study the effects of 2 different ankle braces on the neuromuscular factors influencing ankle stiffness.

Design:

Mixed-model repeated-measures design.

Setting:

Research laboratory.

Patients or Other Participants:

Twenty-eight physically active participants composing 2 groups: 14 with unilateral functional ankle instability (age  =  26.19 ± 6.46 years, height  =  166.07 ± 12.90 cm, mass  =  69.90 ± 13.46 kg) and 14 with bilaterally stable ankles (age  =  23.76 ± 5.82 years, height  =  174.00 ± 11.67 cm, mass  =  68.60 ± 13.12 kg).

Intervention(s):

Participants were fitted with surface electromyography electrodes over the peroneus longus, peroneus brevis, tibialis anterior, and soleus muscles. Each participant received transient motion oscillations to his or her ankle on a custom-built medial-lateral swaying cradle in each of 3 conditions: no ankle brace (NB), lace-up brace (LU), and semirigid brace (SR).

Main Outcome Measure(s):

Ankle stiffness as measured by the cradle and preactivation levels (percentage of maximal voluntary isometric contraction) of the 4 test muscles.

Results:

Stiffness levels increased across brace conditions (NB  =  24.79 ± 6.59 Nm/rad, LU  =  28.29 ± 7.05 Nm/rad, SR  =  33.22 ± 8.78 Nm/rad; F_2,52  =  66.185, P < .001). No differences were found between groups for rotational stiffness (stable  =  27.36 ± 6.17 Nm/rad, unstable  =  30.18 ± 8.21 Nm/rad; F_1,26  =  1.084, P  =  .307). Preactivation levels did not change for any of the tested muscles with the application of an ankle brace (F_2,52  =  1.326, P  =  .275).

Conclusions:

The increase in ankle rotational stiffness with the addition of an ankle brace and the lack of any demonstrable neuromuscular changes suggested ankle braces passively contributed to the stability of the system.     

A close association of body cell mass loss with disease activity and disability in Chinese patients with rheumatoid arthritis

OBJECTIVES:

To investigate the association of body cell mass loss with disease activity and disability in rheumatoid arthritis patients.

INTRODUCTION:

Rheumatoid cachexia, defined as the loss of body cell mass, is important but under-recognized and contributes to morbidity and mortality in patients with rheumatoid arthritis.

METHODS:

One hundred forty-nine rheumatoid arthritis patients and 53 healthy, non-rheumatoid arthritis control subjects underwent anthropometric measurements of body mass index and waist and hip circumferences. Bioelectrical impedance analysis was used to determine the subjects'' body compositions, including fat mass, skeletal lean mass, and body cell mass. The disease activity of rheumatoid arthritis was assessed using C-reactive protein serum, the erythrocyte sedimentation rate and the 28-joint disease activity score, while disability was evaluated using a health assessment questionnaire.

RESULTS:

Rheumatoid arthritis patients had lower waist-to-hip ratio (0.86±0.07 vs. 0.95±0.06; p<0.001) and lower skeletal lean mass indexes (14.44±1.52 vs. 15.18±1.35; p = 0.002) than those in the healthy control group. Compared with rheumatoid arthritis patients with higher body cell masses, those with body cell masses lower than median had higher erythrocyte sedimentation rates (40.10±27.33 vs. 25.09±14.85; p<0.001), higher disease activity scores (5.36±3.79 vs. 4.23±1.21; p = 0.022) and greater disability as measured by health assessment questionnaire scores (1.26±0.79 vs. 0.87±0.79; p = 0.004).

CONCLUSIONS:

The loss of body cell mass is associated with higher disease activity and greater disability in rheumatoid arthritis patients. Body composition determined by bioelectrical impedance analysis can provide valuable information for a rheumatologist to more rapidly recognize rheumatoid cachexia in rheumatoid arthritis patients.