Favorable outcomes of posterior cruciate-stabilized inserts over ultracongruent inserts in total knee arthroplasty.

OBJECTIVE: Posterior cruciate-stabilized (PS) and ultracongruent (UC) inserts are used during total knee arthroplasty (TKA), but superiority in gaining postoperative knee flexion and functionality remains contested. Therefore, this study compared postoperative outcomes between PS and UC inserts. METHODS: A retrospective review evaluated unilateral or bilateral TKAs with PS or UC inserts from August 2011 to March 2020. Nonparametric statistics were performed to evaluate differences in patient demographics, pre- and postknee flexion and Knee Society Knee (KSS-K) and Function Score (KSS-F). Univariate and multivariable regressions were performed to evaluate the influence on postoperative knee flexion ≥ 120°, presented as odds ratios (OR) and 95% confidence intervals (CI). RESULTS: Patient demographics were not significantly different between the 577 PS and 399 UC knees evaluated. Postoperatively, a larger proportion of UC knees demonstrated knee flexion < 120° (36.0% vs. 18.6%, p < 0.001) and lower KSS-K (91.0 ± 8.7 vs. 91.6 ± 10.3, p < 0.001) and KSS-F (76.8 ± 21.6 vs. 79.9 ± 21.6, p = 0.007) than the PS group. The PS group had greater improvement in flexion angle (4.9° ± 14.9° vs. 1.0° ± 15.6°, p < 0.001) and KSS-F (27.3 ± 23.3 vs. 23.1 ± 25.3, p = 0.007) as compared to that of UC patients. Patients with preoperative flexion < 120° (OR 2.787, CI 2.066-3.761; p < 0.001), higher body mass index (OR 1.033, CI 1.006-1.061; p = 0.017) and UC insert (OR 2.461, CI 1.832-3.307; p < 0.001) were less likely to achieve flexion ≥ 120°. CONCLUSION: Favorable clinical and functional outcomes were noted in the PS group as compared to UC inserts in TKA. The greater improvement in overall knee flexion may suggest the PS insert may be especially appropriate for patients with lower preoperative range of motion. LEVEL OF EVIDENCE: III, retrospective comparative study.

Musculoskeletal Injury in Reserve Officers' Training Corps: A Report From the Athletic Training Practice-Based Research Network.

BACKGROUND: Reserve Officers' Training Corps (ROTC) cadets must meet the same physical standards as active duty military servicemembers and undergo organized physical training (PT). ROTC participation, like all physical activity, can result in training-related musculoskeletal injury (MSKI), and of course, cadets could sustain MSKI outside of ROTC. However, MSKI incidence in ROTC programs is largely unknown. PURPOSE: To describe patient and injury demographics of MSKI in 5 universities' Army ROTC programs. STUDY DESIGN: Descriptive epidemiology study. METHODS: A retrospective chart review of electronic medical records was performed using the Athletic Training Practice-Based Research Network (AT-PBRN). Athletic trainers at 5 clinical practice sites within the AT-PBRN documented injury assessments via a web-based electronic medical record system. Medical records during the 2017-2018 and 2018-2019 academic years were used for analysis. Summary statistics were calculated for age, sex, height, body mass, military science year, training ability group, mechanism of injury, activity type associated with injury, anatomic location of injury, participation status, injury severity, and diagnosis. RESULTS: A total of 364 unique injuries were documented. Cadets in the most advanced fitness group (Alpha; n = 148/364) and in their third year of training (n = 97/364) presented with the most injuries. Injuries most commonly occurred during PT (n = 165/364). Insidious onset (n = 146/364) and noncontact (n = 115/364) mechanisms of injury were prevalent. The most frequent anatomic location of injury was the knee (n = 71/364) followed by the ankle (n = 57/364). General sprain/strain was the most frequent International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code reported (n = 34/364). CONCLUSION: The knee was the most frequent location of MSKI in ROTC participants, and most MSKIs had insidious onset. Cadets with higher injury frequency were high achieving (Alpha) and in a critical time point in ROTC (military science year 3). The majority of MSKIs can be attributed to ROTC training, with PT being the most frequent activity associated with injury. Civilian health care providers, from whom ROTC cadets will most likely seek medical attention, need to be aware of ROTC physical demands as well as the characteristics of training-related injuries.

Fatigue-Induced Hip-Abductor Weakness and Changes in Biomechanical Risk Factors for Running-Related Injuries.

CONTEXT: Despite overlap between hip-abductor (HABD) weakness and fatigue-induced changes in running, the interaction of these theorized contributors to running injuries has been underevaluated. OBJECTIVE: To assess the effects of a fatiguing run on HABD torque and evaluate the correlation between HABD torque and previously identified running-related injury pathomechanics while participants were rested or fatigued. DESIGN: Crossover study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 38 healthy, physically active males (age = 21.61 ± 4.02 years, height = 1.78 ± 0.08 m, body mass = 76.00 ± 12.39 kg). INTERVENTION(S): Data collection consisted of rested-state collection, a fatiguing treadmill-run protocol, and fatigued-state collection. For the HABD measures, side-lying handheld-dynamometer isometric tests were performed and converted to torque using femur length. For the gait analysis, kinematic (240 Hz) and kinetic (960 Hz) running (4.0 m/s) data were collected for 3 trials. The fatigue protocol involved a graded exercise test and 80% o2max run to exhaustion. Immediately after the run, fatigued-state measures were obtained. MAIN OUTCOME MEASURE(S): Variables of interest were HABD torque and peak angles, velocities, and moments for hip and knee adduction and internal rotation. Differences between conditions were compared using paired t tests. Pearson correlation coefficients were calculated to evaluate relationships between HABD torque and biomechanical variables. RESULTS: Fatigue decreased HABD torque and increased hip-adduction angle, knee-adduction velocity, and hip and knee internal-rotation velocities and moments (all P values < .05). In the rested state, HABD torque was correlated with hip-adduction velocity (r = -0.322, P = .049). In the fatigued state, HABD torque was correlated with hip-adduction velocity (r = -0.393, P = .015), hip internal-rotation velocity (r = -0.410, P = .01), and knee-adduction angle (r = 0.385, P = .017) and velocity (r = -0.378, P = .019). CONCLUSIONS: Changes in joint velocities due to fatigue and correlations between HABD torque and hip- and knee-joint velocities highlight the need to consider not only the quantity of HABD strength but also the rate of eccentric control of HABDs.

The effect of Kinesio-tape® on pain and vertical jump performance in active individuals with patellar tendinopathy.

BACKGROUND: Patellar tendinopathy is a common inflammatory condition in athletes who undergo large volumes of running and jumping. Kinesio-tape® (KT) is proposed to provide pain relief; however, its effect has not been examined on patellar tendinopathy. OBJECTIVE: To examine the effects of KT on pain modulation for active individuals with patellar tendinopathy during functional activities. METHODS: Thirteen symptomatic knees from seven college-aged females (6 bilateral; 1 unilateral) were included. Participants underwent three data collection sessions with KT, sham, and no tape (NT) in a randomized order. During the session, participants performed a maximum vertical jump, single-leg squats and isometric knee extension. The KT intervention was applied according to the KT manual and the sham utilized the same pattern without tension. Pain level was evaluated using the numeric pain scale before, during and after each activity. Function was assessed as maximum vertical jump height and maximum isometric strength. A separate repeated measures ANOVA was used to compare each dependent variable (pain level, vertical jump height, and isometric strength) among the conditions. RESULTS: Reported pain scores were significantly lower (p = 0.05) during the maximal vertical jump test for KT (3.38 ± 1.26) compared to NT (4.54 ± 2.22). Significantly lower jump heights were found under KT (17.73 ± 3.06in) during the maximum vertical jump test compared to sham (18.65 ± 2.17in, p = 0.000) and NT (18.18 ± 2.93in, p = 0.008). CONCLUSIONS: The use of the KT tape with a tendon corrective strip and muscle facilitative strip was effective for decreasing pain associated with patellar tendinopathy during jump landing but led to decreased maximum jump height. CLINICAL TRIAL IDENTIFIER: NCT04153877.

The effect of patellar thickness on gait biomechanics following total knee arthroplasty.

BACKGROUND: Patella resurfacing is commonly performed during total knee arthroplasty; however, determining the appropriate patellar thickness remains a challenge. The purpose of this study was to evaluate the role of post-TKA patellar thickness on knee extensor strength and biomechanical joint loading forces during walking and stair negotiation. METHODS: Fifteen patients (21 knees) underwent gait analysis prior to TKA and post-TKA at six weeks, three months, six months, and one year. Knee extensor strength and biomechanics were collected during level walking and stair negotiation and analyzed using Pearson correlation coefficients. RESULTS: Knee extensor strength was positively correlated to patellar thickness at three months and one year post-TKA (p ≤ .05). During walking, no significant correlations were present. During stair ascent, there was a positive correlation between patellar thickness and peak knee flexion angle one year post-TKA (p ≤ .05). During stair descent, there was a positive correlation between patellar thickness and maximum vertical ground reaction forces at one year post-TKA (p ≤ .01). CONCLUSIONS: The loss of patellar thickness when compared to measured pre-resurfacing thickness was correlated with a decrease in knee extensor strength; however, changes in patellar thickness were not significantly correlated to biomechanical loading forces during walking. Increases in demand of activity increase the torque to the knee joint, which elicit increases in compensatory motions, likely reducing the extent to which differences in joint loading during stair negotiation may be attributable to changes in patellar thickness. Therefore, the effect of post-patellar thickness on patient function in primary TKA is limited.

Fixed Distal Femoral Cut of 6° Valgus in Total Knee Arthroplasty: A Radiographic Review of 788 Consecutive Cases.

BACKGROUND: In place of the mechanical axis (MA), the use of the variable tibiofemoral angle is frequently used to plan measured resection bony cuts during total knee arthroplasty (TKA). This angle, coupled with operator-dependent variability of intramedullary distal femoral cutting guides, has the potential for catastrophic outcomes. Therefore, a simpler, fixed femoral cut of 6° valgus may be more appropriate when direct measurement of the MA is not possible. METHODS: This was a retrospective study of 788 consecutive TKAs, in which the distal femoral cut was set to 6° valgus. The preoperative and 6-week postoperative MA were measured on hip-to-ankle radiographs. Data were evaluated as a group as well as grouped by preoperative deformity (MA < -3°, -3° < MA < 3°, 3° < MA). RESULTS: Following TKA, MA alignment for all patients was 0.0° ± 2.3° (range, -7.0° to 8.0°). When grouped by pre-TKA alignment, 548 patients were considered varus (MA < -3°), 137 were neutral (-3° < MA < 3°), and 103 patients were valgus (3° < MA). When evaluating the post-TKA alignment achieved in the 3 groups, neutral alignment (-3° < MA < 3°) was established in 86.5% of varus patients, 86.1% of neutral patients, and 82.5% of valgus patients. CONCLUSION: A standard distal femoral cut of 6° resulted in a neutral MA in 86% of patients. While no single technique will be correct for all deformities, in the absence of sophisticated preoperative planning aids, this simple technique could provide a more reliable surgical technique than the measured tibiofemoral angle.

Allometric Grip Strength Norms for American Children.

Kocher, MH, Oba, Y, Kimura, IF, Stickley, CD, Morgan, CF, and Hetzler, RK. Allometric grip strength norms for American children. J Strength Cond Res 33(8): 2251-2261, 2019-To develop normative data from a large cohort of American school children (ages 6-18) for unscaled and allometrically scaled handgrip strength data that are uninfluenced by body size (body mass [BM] and stature [Ht]). Data (age, handgrip strength, BM, and Ht) were collected from the 2011-2012 and 2013-2014 National Health and Nutrition Examination Survey databases, resulting in 4,665 cases (2,384 boys and 2,281 girls). Multiple log-linear regressions were used to determine allometric exponents for BM and Ht separately for each age and sex to satisfy the common exponent and group difference principles described by Vanderburgh. Appropriateness of the allometric model was assessed through regression diagnostics, including normality and homoscedasticity of residuals. Allometrically scaled, ratio-scaled, and unscaled grip strength were then correlated with BM and Ht to examine the effectiveness of the procedure in controlling for body size. The data did not allow for development of a common exponent across age and sex that did not violate the common exponent and group difference principles. Correlations between allometrically scaled handgrip strength with BM and Ht were not significant (p ≤ 0.479) and approached zero, unlike correlations of unscaled handgrip strength with BM and Ht (p < 0.001 for all), indicating that allometric scaling was successful in removing the influence of body size. Allometric scaling handgrip strength by age and sex effectively controls for body size (Ht and BM) and perhaps maturation (Ht). The allometric exponents and normative values developed can be used to compare handgrip strength within age and sex while controlling for body size.

The effectiveness of scaling procedures for comparing ground reaction forces.

Various scaling methods are used when attempting to remove the influence of anthropometric differences on ground reaction forces (GRF) when comparing groups. Though commonly used, ratio scaling often results in an over-correction. Allometric scaling has previously been suggested for kinetic variables but its effectiveness in partialing out the effect of anthropometrics is unknown due to a lack of consistent application. This study examined the effectiveness of allometric scaling vertical, braking and propulsive GRF and loading rate for 84 males and 47 females while running at 4.0 m/s. Raw, unfiltered data were ratio scaled by body mass (BM), height (HT), and BM multiplied by HT (BM∗HT). Gender specific exponents for allometric scaling were determined by performing a log-linear (for BM and HT individually) or log-multilinear regression (BMHT). Pearson productmoment correlations were used to assess the effectiveness of each scaling method. Ratio scaling by BM, HT, or BM∗HT resulted in an over-correction of the data for most variables and left a considerable portion of the variance still attributable to anthropometrics. Allometric scaling by BM successfully removed the effect of BM and HT for all variables except for braking GRF in males and vertical GRF in females. However, allometric scaling for BMHT successfully removed the effect of BM and HT for all reactionary forces in both genders. Based on these results, allometric scaling for BMHT was the most appropriate scaling method for partialing out the effect of BM and HT on kinetic variables to allow for effective comparisons between groups or individuals.

Dynamic Varus and the Development of Iliotibial Band Syndrome.

CONTEXT: Although the risk of osteoarthritis development after acute knee injury has been widely studied, the long-term consequences of knee overuse injury are not well understood. OBJECTIVE: To identify the relationship between gait-related risk factors associated with osteoarthritis and the development of iliotibial band syndrome (ITBS) in members of a single University Army Reserve Officers' Training Corps unit. DESIGN: Prospective cohort study. SETTING: Biomechanics laboratory. PATIENTS OR OTHER PARTICIPANTS: Sixty-eight cadets undergoing standardized physical fitness training. INTERVENTION(S): Three-dimensional lower extremity kinematics (240 Hz) and kinetics (960 Hz) were collected for 3 bilateral trials during shod running at 4.0 m/s ± 10%. Injury tracking was conducted for 7 months of training. MAIN OUTCOME MEASURE(S): Biomechanical variables, including varus thrust and knee-adduction moment, were compared between the injured and control groups. RESULTS: Twenty-six cadets with no history of overuse injury served as the control group, whereas 6 cadets (7 limbs) who developed ITBS that required them to modify their training program or seek medical care (or both) served as the injured group. Maximum varus velocity was higher ( P = .006) and occurred sooner during stance ( P = .04) in the injured group than in the control group, indicating greater varus thrust. Maximum knee-varus angle and maximum knee-adduction moment were higher ( P = .02 and P = .002, respectively) and vertical stiffness was lower ( P = .03) in the injured group. CONCLUSIONS: Measures of dynamic varus stability appeared to be altered in individuals who developed ITBS. Biomechanical knee variables previously identified as increasing the risk for knee osteoarthritis were also associated with the development of ITBS in healthy adults.

The effects of ankle braces and taping on lower extremity running kinematics and energy expenditure in healthy, non-injured adults.

Ankle braces and taping are commonly used to prevent ankle sprains and allow return to play following injury, however, it is unclear how passive restriction of joint motion may effect running gait kinematics and energy expenditure during exercise. The purpose of this study was to determine the effect of different types of ankle supports on lower extremity kinematics and energy expenditure during continuous running. Thirteen healthy physically active adults ran at self-selected speed on the treadmill for 30min in four different ankle support conditions: semi-rigid hinged brace, lace-up brace, tape and control. Three-dimensional lower extremity kinematics and energy expenditure were recorded every five minutes. The semi-rigid hinged brace was most effective in restricting frontal plane ankle motion. The lace-up brace and tape restricted sagittal plane ankle motion, while semi-rigid hinged bracing allowed for normal sagittal plane ankle kinematics. Kinematic changes from all three ankle supports were generally persistent through 25-30min of exercise. Only tape influenced knee kinematics, limiting flexion velocity and flexion-extension excursion. Small but significant increased in energy expenditure was found in tape and semi-rigid hinged brace conditions; however, the increases were not to any practically significant level (<0.5kcal/min).

Allometric Grip Strength Norms for Children of Hawaiian Lineage.

The purpose of the study was to determine allometric exponents for scaling grip strength in children that effectively control for body mass (BM) and stature (Ht) and to develop normative grip strength data for Hawaiian children. One thousand, four hundred thirty-seven students (754 boys) from a rural community in Hawaii participated in this 5-year study, resulting in 2,567 data points. Handgrip strength, BM, and Ht were collected every year. Multiple log-linear regression was used to determine allometric exponents for BM and Ht. Appropriateness of the allometric model was assessed through regression diagnostics, including normality of residuals and homoscedasticity. Allometrically scaled, ratio-scaled, and unscaled grip strength were then correlated with BM and Ht to examine the effectiveness of the procedure in controlling for body size. Allometric exponents for BM and Ht were calculated separately for each age group of boys and girls to satisfy the common exponent and group difference principles described by Vanderburgh. Unscaled grip strength had moderate to strong positive correlations with BM and Ht (p ≤ 0.05 for all) for all age groups. Ratio-scaled handgrip strength had significant moderate to strong negative correlations with BM (p ≤ 0.05 for all) and, to a lesser extent, Ht (p ≤ 0.05 for 8- to 12-year-old boys; p ≤ 0.05 for 8- to 12- and 14-year-old girls). Correlations between allometrically scaled handgrip strength and BM and Ht were not significant and approached zero. This study was the first to allometrically scale handgrip strength for BM and Ht in Hawaiian children. Allometric scaling applied to grip strength provides a useful expression of grip strength free of the confounding influence of body size.

Asymmetry between lower limbs during rested and fatigued state running gait in healthy individuals.

Although normal gait is often considered symmetrical in healthy populations, differences between limbs during walking suggest that limbs may be used preferentially for braking or propulsion. The purpose of this study was to evaluate kinematic and kinetic variables, at both rested state and following a two-stage treadmill fatiguing run, for asymmetry between limbs. Kinematic (240Hz) and kinetic (960Hz) running data were collected bilaterally for 20 physically active individuals at both rested and fatigued states. Symmetry angles were calculated to quantify asymmetry magnitude at rested and fatigued states. Paired t-tests were used to evaluate differences between right and left limbs at rested and fatigued states, as well as rested and fatigued states symmetry angles. Variables that have been previously associated with the development of overuse injuries, such as knee internal rotation, knee stiffness, loading rate, and adduction free moment, were found to be significantly different between limbs at both rested and fatigued states. Significant differences in vertical stiffness were found, potentially indicating functional asymmetry during running. Symmetry angle was used to investigate changes in percentage of asymmetry at rested and fatigued states. Small (1-6%), but significant decreases in vertical stiffness, loading rate, and free moment symmetry angles indicate that these variables may become more symmetrical with fatigue. Knee internal rotation and knee stiffness became more asymmetrical with fatigue, increasing by 14% and 5.3%, respectively. The findings of the current study indicate that fatigue induced changes in gait may progress knee movement pattern asymmetry.

Standard Radiographs Are Not Sufficient for Assessing Knee Mechanical Axis in Patients With Advanced Osteoarthritis.

BACKGROUND: The use of standard radiographs, and measured tibiofemoral angle (TFA), to assess lower extremity alignment is commonly practiced despite limited knowledge of its relationship to the mechanical axis (MA), as measured on hip-to-ankle (HTA) radiographs. This study assessed the predictive accuracy of previously developed equations, developed gender-specific regression equations using predictors from standard radiographs, and the clinical effectiveness of these equations in a large sample of cases using HTA radiographs as a gold standard. METHODS: The MA was measured on HTA radiographs, whereas TFA and femoral angle were measured on standard radiographs in 788 cases diagnosed with knee osteoarthritis. RESULTS: Multiple regression analyses indicated that TFA, femoral angle, and height were the strongest factors associated with the predicting MA, accounting for 83% of the variance for men and 86% for women, but were able to predict only the actual MA within ±3° in 66% of men and 69% of women. When applied to previously reported regression equations with similar results, the best predicative accuracy obtained within ±3° was 61% and 63% of men and women, respectively. CONCLUSION: Standard radiographs are not sufficient for determining MA, and HTA radiographs should be used while making surgical decisions aimed at correcting alignment to within ±3° or for assessing alignment post-total knee arthroplasty. In addition, surgical alignment outcomes reported in previous research using standard radiographs should be viewed with caution.

Step-rate recommendations for moderate-intensity walking in overweight/obese and healthy weight children.

BACKGROUND: Physical activity guidelines for youth and adults include recommendations for moderate intensity activity to attain health benefits. Indirect calorimetry studies have consistently reported a 100 step·min(-1) threshold for moderate intensity walking in adults. No indirect calorimetry studies have investigated step-rate thresholds in children and therefore the primary purpose of the study was to determine preliminary step-rate thresholds for moderate physical activity walking in children. METHODS: Oxygen consumption was measured at rest and used to determine 3 and 4 age-adjusted metabolic equivalents (A-AMETs) for 4 treadmill trials (self-selected, 2.5, 3.0, and 3.5 MPH). Two trained observers simultaneously counted children's steps during each walking trial. Step-rate thresholds associated with moderate-intensity activity, defined as 3 and 4 A-AMETs, were determined using hierarchical linear modeling. RESULTS: Regression analysis determined an overall step rate of 112 and 134 steps·min(-1) for 3 and 4 A-AMETs respectively. Body mass index (BMI) weight status and age were positively related to A-AMETs. CONCLUSIONS: We suggest age and BMI weight status specific recommendations that range from a low of 100 step·min(-1) threshold (3 A-AMETs) for overweight/obese 11- to 12-year-olds to a high of 140 step·min(-1) threshold (4 A-AMETs) for healthy weight 9- to 10-year-old children.

Allometric scaling of strength scores in NCAA division I-A football athletes.

This study examined population-specific allometric exponents to control for the effect of body mass (BM) on bench press, clean, and squat strength measures among Division I-A collegiate football athletes. One repetition maximum data were obtained from a university pre-season football strength assessment (bench press, n = 207; clean, n = 88; and squat n = 86) and categorized into 3 groups by positions (line, linebacker, and skill). Regression diagnostics and correlations of scaled strength data to BM were used to assess the efficacy of the allometric scaling model and contrasted with that of ratio scaling and theoretically based allometric exponents of 0.67 and 0.33. The log-linear regression models yielded the following exponents (b): b = 0.559, 0.287, and 0.496 for bench press, clean, and squat, respectively. Correlations between bench press, clean, and squat to BM were r = -0.024, -0.047, and -0.018, respectively, suggesting that the derived allometric exponents were effective in partialling out the effect of BM on these lifts and removing between-group differences. Conversely, unscaled, ratio-scaled, and allometrically scaled (b = 0.67 or 0.33) data resulted in significant differences between groups. It is suggested that the exponents derived in the present study be used for allometrically scaling strength measures in National Collegiate Athletic Association Division I-A football athletes. Use of the normative percentile rank scores provide coaches and trainers with a valid means of judging the effectiveness of their training programs by allowing comparisons between individuals without the confounding influence of BM.

Aerobic fitness levels and validation of a non exercise VO2max prediction equation for HIV-infected patients on HAART.

BACKGROUND: Non-exercise (N-EX) questionnaires have been developed to determine maximal oxygen consumption (VO2max) in healthy populations. There are limited reliable and validated N-EX questionnaires for the HIV+ population that provide estimates of habitual physical activity and not VO2max. OBJECTIVES: To determine how well regression equations developed previously on healthy populations, including N-EX prediction equations for VO2max and age-predicted maximal heart rates (APMHR), worked on an HIV+ population; and to develop a specific N-EX prediction equation for VO2max and APMHR for HIV+ individuals. METHODS: Sixty-six HIV+ participants on stable HAART completed 4 N-EX questionnaires and performed a maximal graded exercise test. RESULTS: Sixty males and 6 females were included; mean (SD) age was 49.2 (8.2) years; CD4 count was 516.0 ± 253.0 cells·mm-3; and 92% had undetectable HIV PCR. Mean VO2max was 29.2 ± 7.6 (range, 14.4-49.4) mL·kg-1·min-1 Despite positive correlations with VO2max, previously published N-EX VO2max equations produced results significantly different than actual VO2 scores (P < .0001). An HIV+ specific N-EX equation was developed and produced similar mean VO2max values, R = 0.71, when compared to achieved VO2max (P = .53). CONCLUSION: HIV+ individuals tend to be sedentary and unfit, putting them at increased risk for the development of chronic diseases associated with a sedentary lifestyle. Based on the level of error associated with utilizing APMHR and N-EX VO2max equations with HIV+ individuals, neither should be used in this population for exercise prescription.

Validity and reliability of the Hawaii anaerobic run test.

This study examined the reliability and validity of the Hawaii anaerobic run test (HART) by comparing anaerobic capacity measures obtained to those during the Wingate Anaerobic Test (WAnT). Ninety-six healthy physically active volunteers (age, 22.0 ± 2.8 years; height, 163.9 ± 9.5 cm; body mass, 70.6 ± 14.7 kg; body fat %, 19.29 ± 5.39%) participated in this study. Each participant performed 2 anaerobic capacity tests: the WAnT and the HART by random assignment on separate days. The reliability of the HART was calculated from 2 separate trials of the test and then determined through intraclass correlation coefficients (ICCs). Blood samples were collected, and lactate was analyzed both pretest and posttest for each of the 2 exercise modes. Heart rate and rate of perceived exertion were also measured pre- and post-exercise. Hawaii anaerobic run test peak and mean momentum were calculated as body mass times highest or average split velocity, respectively. Intraclass correlation coefficients between trials of the HART for peak and mean momentum were 0.98 and 0.99, respectively (SEM = 18.8 and 25.7, respectively). Validity of the HART was established through comparison of momentum on the HART with power on the WAnT. High correlations were found between peak power and peak momentum (r = 0.88), as well as mean power and mean momentum (r = 0.94). The HART was considered to be a reliable test of anaerobic power. The HART was also determined to be a valid test of anaerobic power when compared with the WAnT. When testing healthy college-aged individuals, the HART offers an easy and inexpensive alternative maximal effort anaerobic power test to other established tests.

Long-term outcomes of a dynamic ankle-foot orthosis on gait characteristics of a service member with incomplete nerve injury to the lower extremity: a case report.

This case study reports a 5-year follow-up of a 32-year-old male service member who suffered polytrauma in 2007 following a Humvee rollover in Afghanistan. The service member's injured left lower extremity was salvaged, but severe damage to the lumbosacral plexus and significant injuries to the pelvis, hip, and femur resulted in near total paralysis and foot drop of the left lower limb. Two years of multiple substandard ankle-foot orthotic devices pushed him to investigate a dynamic ankle-foot orthotic (DAFO) with energy storing capability, which allowed him to remain on active duty and deploy for a second tour while wearing the device. The anecdotal improvements described by this service member prompted a biomechanical analysis of walking and running gait, comparing a shoes only condition to the DAFO. Results of gait analysis demonstrated an improvement in spatial-temporal parameters in both walking and running, improved sagittal angles and moments at the ankle, knee, and hip, greater ankle stability through decreased dorsiflexion excursion, and a marked increase in ankle power while running. Most notably, the service member credits this device for substantial improvement in quality of life including total cessation of pain medication and return to regular vigorous activity.

Allometric scaling of Wingate anaerobic power test scores in men.

This study examined the appropriate magnitude of allometric scaling of the Wingate anaerobic test (WAnT) power data for body mass (BM) and established normative data for the WAnT for adult men. Eighty-three men completed a standard WAnT using 0.1 kg·kg(-1) BM resistance. Allometric exponents and percentile ranks for 1-second peak power (PP), 5-second PP, and mean power (MP) were established. The Predicted Residual Sum of Squares (PRESS) procedure was used to assess external validity while avoiding data splitting. The mean 1-second PP, 5-second PP, and MP were 1,049.1 ± 168.8 W, 1,013.4 ± 158.6 W, and 777.9 ± 105.0 W, respectively. Allometric exponents for 1-second PP, 5-second PP, and MP scaled for BM were b = 0.89, 0.88, and 0.86, respectively. Correlations between allometrically scaled 1-second PP, 5-second PP, and MP, and BM were r = -0.03, -0.03, and -0.02, respectively, suggesting that the allometric exponents derived were effective in partialling out the effect of BM on WAnT values. The PRESS procedure values resulted in small decreases in R² (0.03, 0.04, and 0.02 for 1-second PP, 5-second PP, and MP, respectively) suggesting acceptable levels of external validity when applied to independent samples. The allometric exponents and normative values provide a useful tool for comparing WAnT scores in college-aged females without the confounding effect of BM. It is suggested that exponents of b = 0.89 (1-second PP), b = 0.88 (5-second PP), and b = 0.86 (MP) be used for allometrically scaling WAnT power values in healthy adult men and that the confidence limits for these allometric exponents be considered as 0.66-1.0 for PP and 0.69-1.0 for MP. The use of these exponents in allometric scaling of male WAnT power values provide coaches and practitioners with valid means for comparing power production between individuals without the confounding influence of BM.

Validation of a nonexercise prediction equation of anaerobic power.

This study examined the validity of estimating anaerobic power in college-aged students using anthropometric data and a paper and pencil test. Peak power (PP) and mean power (MP) were determined for 157 subjects (92 men and 65 women) using a standard Wingate anaerobic test (WAnT) at a resistance of 0.075 and 0.10 kg·body mass for women and men, respectively. Subjects completed previously established paper and pencil tests for assessing aerobic capacity and rated their ability to perform tasks related to anaerobic power, such as their vertical jump height relative to peers. Descriptive statistics were generated, and multiple regression was performed using SAS v9.1 to assess the ability of paper and pencil tests to predict PP and MP from the WAnT. Mean (±SD) age, height, body mass, body mass index, PP, and MP for subjects were 22.1 ± 2.5 years, 175.6 ± 7.5 cm, 78.5 ± 11.4 kg, 25.4 ± 3.0 kg·m, 1015.2 ± 169.7 W, and 784.5 ± 122.1 W and 22.0 ± 3.0 years, 163.6 ± 7.4 cm, 61.1 ± 10.4 kg, 22.8 ± 3.4 kg·m, 593.0 ± 102.4 W, and 478.8 ± 72.8 W, respectively. Mean estimated jump height (EJHt) rating values were 5.8 ± 1.5 and 4.7 ± 1.5 (on a 1-9 Likert-type scale) for men and women, respectively. The following multiple regression models were developed:PP = -34.5 + 249.6 (gender; female = 0, male = 1) + 8.1 (BMkg) + 27.8 (EJHt) (R = 0.82, SEE = 106.6 W);MP = -37.7 + 163.7 (gender) + 6.7 (BMkg) + 22.8 (EJHt) (R = 0.87, SEE = 65.5 W).It was concluded that valid estimates for PP and MP could be obtained from anthropometric data and a single question paper and pencil test asking subjects to estimate relative jumping ability, without the need for performing the Wingate anaerobic cycle test.