Search Results

You are looking at 1 - 6 of 6 items for :

  • Author: Christopher Kuenze x
  • Athletic Training, Therapy, and Rehabilitation x
Clear All Modify Search
Restricted access

Christopher Kuenze, Jay Hertel and Joseph M. Hart

Purpose:

Persistent quadriceps weakness due to arthrogenic muscle inhibition (AMI) has been reported after anterior cruciate ligament (ACL) reconstruction. Fatiguing exercise has been shown to alter lower extremity muscle function and gait mechanics, which may be related to injury risk. The effects of exercise on lower extremity function in the presence of AMI are not currently understood. The purpose of this study was to compare the effect of 30 min of exercise on quadriceps muscle function and soleus motoneuron-pool excitability in ACL-reconstructed participants and healthy controls.

Methods:

Twenty-six (13 women, 13 men) healthy and 26 (13 women, 13 men) ACL-reconstructed recreationally active volunteers were recruited for a case-control laboratory study. All participants completed 30 min of continuous exercise including alternating cycles of inclined-treadmill walking and bouts of squats and step-ups. Knee-extension torque, quadriceps central activation ratio (CAR), soleus H:M ratio, and soleus V:M ratio were measured before and after 30 min of exercise.

Results:

There was a significant group × time interaction for knee-extension torque (P = .002), quadriceps CAR (P = .03), and soleus V:M ratio (P = .03). The effect of exercise was smaller for the ACL-R group than for matched controls for knee-extension torque (ACL-R: %Δ = −4.2 [−8.7, 0.3]; healthy: %Δ = −14.2 [−18.2, −10.2]), quadriceps CAR (ACL-R: %Δ = −5.1 [−8.0, −2.1]; healthy: %Δ = −10.0 [−13.3, −6.7]), and soleus V:M ratio (ACL-R: %Δ = 37.6 [2.1, 73.0]; healthy: %Δ = −24.9 [−38.6, −11.3]).

Conclusion:

Declines in quadriceps and soleus volitional muscle function were of lower magnitude in ACL-R subjects than in healthy matched controls. This response suggests an adaptation experienced by patients with quadriceps AMI that may act to maintain lower extremity function during prolonged exercise.

Restricted access

Christopher Kuenze, Moataz Eltouhky, Abbey Thomas, Mark Sutherlin and Joseph Hart

Context:

Collecting torque data using a multimode dynamometer is common in sports-medicine research. The error in torque measurements across multiple sites and dynamometers has not been established.

Objective:

To assess the validity of 2 calibration protocols across 3 dynamometers and the error associated with torque measurement for each system.

Design:

Observational study.

Setting:

3 university laboratories at separate institutions.

Equipment:

2 Biodex System 3 dynamometers and 1 Biodex System 4 dynamometer.

Interventions:

System calibration was completed using the manufacturer-recommended single-weight method and an experimental calibration method using a series of progressive weights. Both calibration methods were compared with a manually calculated theoretical torque across a range of applied weights.

Main Outcome Measures:

Relative error, absolute error, and percent error were calculated at each weight. Each outcome variable was compared between systems using 95% confidence intervals across low (0–65 Nm), moderate (66–110 Nm), and high (111–165 Nm) torque categorizations.

Results:

Calibration coefficients were established for each system using both calibration protocols. However, within each system the calibration coefficients generated using the single-weight (System 4 = 2.42 [0.90], System 3a = 1.37 [1.11], System 3b = –0.96 [1.45]) and experimental calibration protocols (System 4 = 3.95 [1.08], System 3a = –0.79 [1.23], System 3b = 2.31 [1.66]) were similar and displayed acceptable mean relative error compared with calculated theoretical torque values. Overall, percent error was greatest for all 3 systems in low-torque conditions (System 4 = 11.66% [6.39], System 3a = 6.82% [11.98], System 3b = 4.35% [9.49]). The System 4 significantly overestimated torque across all 3 weight increments, and the System 3b overestimated torque over the moderate-torque increment.

Conclusions:

Conversion of raw voltage to torque values using the single-calibration-weight method is valid and comparable to a more complex multiweight calibration process; however, it is clear that calibration must be done for each individual system to ensure accurate data collection.

Restricted access

Caroline Lisee, Tom Birchmeier, Arthur Yan, Brent Geers, Kaitlin O’Hagan, Callum Davis and Christopher Kuenze

Context: Landing kinetic outcomes are associated with injury risk and may be persistently altered after anterior cruciate ligament injury or reconstruction. However, it is challenging to assess kinetics clinically. The relationship between sound characteristics and kinetics during a limited number of functional tasks has been supported as a potential clinical alternative. Objective: To assess the relationship between kinetics and sound characteristics during a single-leg landing task. Design: Observational Setting: Laboratory. Participants: There was total of 26 healthy participants (15 males/11 females, age = 24.8 [3.6] y, height = 176.0 [9.1] cm, mass = 74.9 [14.4] kg, Tegner Activity Scale = 6.1 [1.1]). Intervention: Participants completed single-leg landings onto a force plate while audio characteristics were recorded. Main Outcome Measures: Peak vertical ground reaction force, linear loading rate, instantaneous loading rate, peak sound magnitude, sound frequency were measured. Means and SDs were calculated for each participant’s individual limbs. Spearman rho correlations were used to assess the relationships between audio characteristics and kinetic outcomes. Results: Peak sound magnitude was positively correlated with normalized peak vertical ground reaction force (ρ = .486, P = .001); linear loading rate (ρ = .491, P = .001); and instantaneous loading rate (ρ = .298, P = .03). Sound frequency was negatively correlated with instantaneous loading rate (ρ = −.444, P = .001). Conclusions: Peak sound magnitude may be more helpful in providing feedback about an individual’s normalized vertical ground reaction force and linear loading rate, and sound frequency may be more helpful in providing feedback about instantaneous loading rate. Further refinement in sound measurement techniques may be required before these findings can be applied in a clinical population.

Restricted access

Christopher Kuenze, Lisa Cadmus-Bertram, Karin Pfieffer, Stephanie Trigsted, Dane Cook, Caroline Lisee and David Bell

Context: Reductions in objectively measured moderate to vigorous physical activity (MVPA) have been reported among individuals with anterior cruciate ligament reconstruction (ACLR). Self-reported measures of physical activity are commonly used to assess participation in physical activity after ACLR despite the lack of evidence to support the validity of such measures within this population. Objective: The objective of this research was to determine the relationships between objectively measured MVPA, self-reported physical activity, and knee function among individuals with ACLR. Setting: University laboratory. Patients (or Other Participants): Thirty-one participants with a history of ACLR (sex: 23 females and 8 males; age = 19.8 [1.4] y) and 31 matched controls (sex: 23 females and 8 males; age = 20.6 [1.7] y) enrolled in this study. Intervention(s): None. Main Outcome Measures: Participants completed self-reported physical activity using the Tegner Activity Scale and the Marx Activity Rating Scale. Participant MVPA was objectively measured using an ActiGraph wGT3X-BT accelerometer for a 7-day period during which the monitor was worn for not less than 10 hours per day. Primary outcome measures were the amount of time spent in MVPA (minutes per week) and time spent in MVPA performed in bouts of ≥10 minutes (minutes per week). Relationships between the Tegner Activity Score, Marx Activity Rating Scale, and objectively measured MVPA variables were assessed using partial Spearman’s rank correlation coefficients after controlling for activity monitor wear time. Results: There were no significant relationships between objectively measured MVPA and self-reported physical activity (ρ ≤ 0.31, P ≥ .05) or self-reported knee-related function (ρ ≤ .41, P ≥ .05) among ACLR participants. Conclusions: Objectively measured physical activity is not significantly related to self-reported physical activity or self-reported knee function among individuals with a history of ACLR. Consideration of objective and self-reported physical activity within this population may provide key insights into disconnects between perception and the reality of physical activity engagement following ACLR.

Restricted access

Christopher Kuenze, Jay Hertel, Susan Saliba, David R. Diduch, Arthur Weltman and Joseph M. Hart

Context:

Normal, symmetrical quadriceps strength is a common clinical goal after anterior cruciate ligament reconstruction (ACLR). Currently, the clinical thresholds for acceptable unilateral quadriceps function and symmetry associated with positive outcomes after return to activity are unclear.

Objective:

To establish quadriceps-activation and knee-extension-torque cutoffs for clinical assessment after return to activity after ACLR.

Design:

Descriptive laboratory study.

Setting:

Laboratory.

Patients:

22 (10 female, 12 male; age = 22.5 ± 5.0 y, height = 172.9 ± 7.1 cm, mass = 74.1 ± 15.5 kg, months since surgery = 31.5 ± 23.5) recreationally active persons with a history of unilateral, primary ACLR at least 6 months prior and 24 (12 female/12 male, age = 21.7 ± 3.6 y, height = 168.0 ± 8.8 cm, mass = 69.3 ± 13.6 kg) recreationally active healthy participants.

Main Outcome Measures:

Patient-reported measures of pain, knee-related function, and physical activity level were recorded for all participants. Normalized knee-extension maximum-voluntary-isometric-contraction (MVIC) torque (Nm/kg) and quadriceps central-activation ratio (CAR, %) were measured bilaterally in all participants. Receiver-operator-characteristic (ROC) curves were used to establish thresholds for unilateral measures of normalized knee-extension MVIC torque and quadriceps CAR, as well as limb-symmetry indices (LSI). ROC curves then established clinical thresholds for normalized knee-extension MVIC torque and quadriceps CAR LSIs associated with healthy knee-related function.

Results:

Involved-quadriceps CAR above 89.3% was the strongest unilateral indicator of healthy-group membership, while quadriceps CAR LSI above 0.996 and knee-extension MVIC torque above 0.940 were the strongest overall indicators. Unilateral normalized knee-extension MVIC torque above 3.00 Nm/kg and quadriceps CAR LSI above 0.992 were the best indicators of good patient-reported knee-related outcomes.

Conclusions:

Threshold values established in this study may provide a guide for clinicians when making return-to-activity decisions after ACLR. Normalized knee-extension MVIC torque (>3.00 Nm/kg) and quadriceps CAR symmetry (>99.6%) are both strong indicators of good patient-reported outcomes after ACLR.

Restricted access

Moataz Eltoukhy, Christopher Kuenze, Jeonghoon Oh, Eryn Apanovitch, Lauren Butler and Joseph F. Signorile

Anterior cruciate ligament (ACL) injury is one of the most common knee injuries among adolescent athletes. Majority of the ACL injuries occur due to pivoting, sudden deceleration, and direction change without contact with any player. Preventive interventions can reduce risks of the ACL injury, thus developing a clinician friendly biomechanical assessment tool to identify athletes with such risk factors is crucial. In this study, the authors investigated the concurrent validity of a commercially available depth sensor, Microsoft Kinect, as a cost-effective alternative to the gold-standard 3-dimensional motion analysis systems in noncontact ACL screening for adolescent athletes during side-cut maneuvers. Study participants performed 45° side-cut maneuvers while collecting data from both systems concurrently. The sagittal and frontal plane kinematics were analyzed during the full stance phase and the first 20% of the stance (early deceleration). Absolute agreement (range: ICC = .767–.989) and consistency (range: ICC = .799–.992) were excellent for all measures except early deceleration frontal plane hip angle, which displayed good absolute agreement (ICC = .643) and consistency (ICC = .625). Findings showed that the Kinect has the potential to be an effective clinical assessment tool for sagittal and frontal plane trunk, hip, and knee kinematics during the side-cut maneuvers.