Intrarater reliability of the Humac NORM isokinetic dynamometer for strength measurements of the knee and shoulder muscles

Lower-Extremity Muscle Strength Symmetry Assessment Through Isokinetic Dynamometry

OBJECTIVE

This study aimed to establish a dominant and non-dominant limb muscle strength evaluation model to evaluate the asymmetry of lower extremity muscle strength.

METHODS

The hip, knee, ankle flexors and extensors of 86 runners were evaluated separately in different contraction modes and at different movement speeds. A principal component analysis was used to establish a model for evaluating dominant and non-dominant lower extremity muscle strength and to comprehensively evaluate the asymmetry of lower extremity muscle strength.

RESULTS

Six main factors were present in both dominant and non-dominant indicators of lower extremity muscle strength, with dominant indicators of lower extremity muscle strength explaining 80.413% of the total variance and non-dominant indicators explaining 78.607% of the total variance.

CONCLUSIONS

In a population of healthy male runners, there were differences in the symmetry of lower limbs in the comprehensive assessment model. The main contribution of the non-dominant side was the knee muscles, and the dominant side was the hip and knee muscles, so this difference should be considered in constructing future muscle strength evaluation models. It is critical to understanding the design and function of the human muscle system, and can reduce the number of meaningful tests we perform on diverse populations and help us reduce asymmetry.

Effect of mixed protein supplementation on golf performance and muscle function: a randomized, double-blind, placebo-controlled study

BACKGROUND

As a relatively novel approach to enhancing skeletal muscle health, mixed protein supplementation has shown similar responses to whey protein. However, no previous studies have examined its impact on golf swing performance. This study aimed to examine the effect of mixed protein supplementation on the swing performance and muscle strength of casual golfers.

METHODS

Sixty participants with a handicap of less than 20 were recruited and randomly assigned to a double-blind, placebo-controlled study design. The participants were divided into two groups: a mixed protein group (MG, n = 30), and a placebo control group (CG, n = 30). They were instructed to ingest either a supplement containing casein calcium, whey protein, and isolated pea protein, or a placebo, once daily for 8 weeks. Pre- and posttests consisted of anthropometric measurements, muscle strength (isokinetic knee and trunk strength, and handgrip strength), 2-minute push-ups, balance, and golf swing performance using a driver and 7-iron.

RESULTS

After the 8-week supplementation period, ANCOVA, using baseline values as covariates, revealed significant differences for driver distance (p = .004) and driver ball speed (p < .001). MG significantly increased driver distance by 5.17 ± 12.8 m (p = .046), driver ball speed by 1.36 ± 2.87 m/s (p = .021). Additionally, significantly improvements were observed in hand grip strength (+2.12 ± 3.47 kg, p = .004), two-minute push-ups (+4.89 ± 8.14 reps, p = .004), and balance score (-0.37 ± 0.69 min, p = .009). No significant differences were observed in body composition parameters (p > .05).

CONCLUSION

The intake of a mixed protein containing both animal and plant proteins had positive effects on golf performance and muscle function. Therefore, mixed proteins may represent a safe and effective approach to enhancing skeletal muscle health in golf players.

Effects of arthroscopic rotator cuff repair on isokinetic muscle function 6 months following surgery: influence of tear type, tear size, and tendon retraction

BACKGROUND

Rotator cuff tears are a common musculoskeletal condition which can lead to functional limitations and impairments in quality of life. The purpose of the present study was to investigate the effects of arthroscopic repair surgery on isokinetic muscle function before and 6-months after surgery. Additionally, the mediating effects of tear type, tear size and tendon retraction were examined.

METHODS

Data from n = 67 patients (56 ± 9 years) with full-thickness rotator cuff tears were analyzed. Before and 6-months after surgery, isokinetic muscle function in external/internal rotation and abduction/adduction movements was assessed. Further, tear size, tear type (Collin classification) and tendon retraction (Patte classification) were analyzed using magnetic resonance imaging.

RESULTS

After statistical analysis, a significant increase in limb symmetry index of external (P < .001), internal rotation (P < .01), abduction (P < .001), and adduction (P < .001) were observed from preto postsurgery. The results revealed that tear size and tendon tear type significantly mediated the functional outcome, with no significant effect of tendon retraction.

CONCLUSION

The present findings point toward the notion that the functional outcome following rotator cuff repair was significantly dependent on tear type and tear size but not tendon retraction. Patients with larger sized tears presented pronounced deficits following 6-months indicating that rehabilitation times need to be adjusted accordingly.

Age-related changes in gait, balance, and strength parameters: A cross-sectional study

BACKGROUND

Longevity is increasing worldwide due to improvements in healthcare and living standards. Aging is often associated with disability and multiple health concerns. To address these challenges, effective interventions are essential. This study investigated potential age-related declines in gait, balance, and strength. We also sought to assess any relationships between these three parameters and explore potential differences between women and men.

METHODS

Healthy individuals over 50 years of age were recruited for this cross-sectional study. Upper extremity (grip) strength and lower extremity (knee) strength of the dominant side were measured. Static balance was performed on the force plate in different situations each for 30 seconds: bilateral stance with eyes open, bilateral stance with eyes closed, as well as dominant leg and non-dominant leg unilateral stance with eyes open. Gait was measured during level walking using an optical motion capture system. Additionally, the dynamic stability margin (DSM) was calculated for the level walking trials.

RESULTS

The study results indicated that gait parameters were not significantly affected by age (p≥0.12), while knee and grip strength, along with several balance parameters, showed a significant decline with age. All individuals were able to maintain their bipedal balance, but their center of pressure movement increased significantly by age (p≤0.028). Z-scores were calculated to compare significant age parameters. Unipedal stance time was found to be the most affected by age compared to other contributing factors (p≤0.001). The duration of unipedal balance showed the most significant change per decade (non-dominant: -0.62 SDs; dominant: -0.53 SDs), while strength measures exhibited the lowest amount of change per decade (grip strength: -0.34 SDs; knee strength: -0.26 SDs). Sex differences were observed exclusively in strength parameters, with no discernible impact on the decline in balance parameters.

CONCLUSIONS

These findings suggest that the duration of unipedal stance can serve as a reliable and gender-independent measure of neuromuscular aging for both elderly male and female subjects.

Analysis of intrarater and interrater reliability of the interactive line protocol for evaluating neuromuscular function in patients with knee injury and observation of psychological state changes

The isokinetic interactive line protocol (ILP) appears to enhance neuromuscular function and may reduce posttraumatic stress and anxiety. However, the reliability of the protocol has not been investigated, nor has it been analyzed in relation to psychological states. A total of 165 participants took part in this study, with ages ranging from 21 to 24 years. The gender distribution was 68.4% male and 31.6% female. There was no significant difference in injury duration between males and females (z=-0.922, P=0.357). The intrarater reliability of the ILP, as indicated by the intraclass correlation coefficient, was high for both concentric and eccentric contractions of the quadriceps (ranging from 0.891 to 0.980). Likewise, the interrater reliability for these contractions was also high (range, 0.873-0.943). Additionally, during the ILP, there was a significant reduction in posttraumatic stress (t=9.795, P<0.001) and anxiety (t=5.965, P<0.001) related to knee reinjury after 2 weeks. Ultimately, the isokinetic game ILP demonstrates high intra- and interrater reliabilities and can be concluded to effectively reduce posttraumatic stress and anxiety when incorporated into retesting.

Effects of 60 versus 30 Minutes of Pilates Exercise on Cervicothoracic Alignment, Muscle Strength, and Endurance in University Students with Upper Crossed Syndrome

Background/Objectives: This study determined the effects of 60 min or 30 min Pilates program on cervicothoracic alignment, muscular strength, and endurance in university students with upper-crossed syndrome (UCS). Methods: Twenty-six university students with UCS were randomly allocated into 60 min Pilates (60 PG, n = 9), 30 min Pilates (30 PG, n = 9), and control (CG, n = 8) groups. The 60 and 30 PG students participated in the Pilates program, focusing on relaxation, stability, mobility, and strengthening of the cervical, thoracic, and scapular muscles for 60 or 30 min per session, twice a week, for 12 weeks. Cervicothoracic alignment was measured using BodyStyle to determine craniovertebral angle (CVA), forward shoulder angle (FSA), head position angle (HPA), head tilt angle (HTA), and kyphosis angle (KA). We measured the muscular strength and endurance of the shoulder on the dominant side. Results: After the intervention, CVA, HPA, HTA, and KA significantly improved in the 60 and 30 PG (all p < 0.01) but not in the CG (p > 0.05). There were no significant differences between the 60 and 30 PG at 4, 8, and 12 weeks. Shoulder strength differed between shoulder flexion and horizontal abduction (p < 0.01). Shoulder endurance differed between extension, flexion, and horizontal abduction (p < 0.05, p < 0.01, and p < 0.001, respectively). Conclusions: This study confirmed the effectiveness of the Pilates program in improving cervicothoracic sagittal alignment and shoulder muscular function in university students with UCS. Additionally, the effects of participating in 60 and 30 min Pilates programs were found to be equivalent. Therefore, encouraging busy university students to participate in at least 30 min of the Pilates program is important.

Changes in isometric mid-thigh pull peak force and symmetry across anterior cruciate ligament reconstruction rehabilitation phases

Background

Whether functionally relevant strength assessments, such as the isometric mid-thigh pull (IMTP), can be used either bilaterally or unilaterally to evaluate and guide rehabilitation progress in those with anterior cruciate ligament reconstruction (ACLR) is under-researched. This study assessed changes in peak force (PF) and asymmetry across 3 phases for bilateral and unilateral IMTP assessments in patients with ACLR. Peak isometric force from the IMTP was compared to peak torque from isokinetic dynamometry as well as against a cohort of healthy, uninjured individuals.

Method

Participants (ACLR, n = 15) completed bilateral and unilateral IMTP assessments at weeks 12 (baseline), 16 (phase 3), and 20 (phase 4) of rehabilitation to evaluate changes in PF and asymmetry. Asymmetry was evaluated using the asymmetry angle. Isometric data from the IMTP were compared to that from an isokinetic dynamometer as well as against a cohort of healthy, uninjured participants (n = 63) allowing for a detailed analysis of limb-specific force production.

Results

The PF during the bilateral IMTP increased for both the injured (0.94 N/kg) and uninjured (0.26 N/kg) limbs from baseline to phase 4, whereas the PF of the injured limb increased by 1.5 N/kg during the unilateral IMTP in the same time frame. Asymmetry values systematically reduced by ∼1% and ∼0.5% for the bilateral and unilateral IMTP tests from baseline to phase 4. Significant differences in PF of the injured limb were evident between those with ACLR and healthy controls across all phases (p = 0.022-0.001). The rate of progression in PF capacity was dependent on test type, amounting to 0.1 and 0.2 body weights per week for the bilateral and unilateral IMTP respectively. Small-to-large correlations (r = 0.12-0.88) were evident between IMTP PF and peak torque from the isokinetic dynamometer as well as between asymmetry metrics from both tests.

Conclusion

The findings suggest that IMTP PF has potential for monitoring changes in PF and asymmetry during the ACLR rehabilitation progress. Both injured limb and uninjured limb show improvement in force-generating capacity, implying a positive adaptation to rehabilitation protocols. The findings highlight that ACLR is a unilateral injury that requires bilateral rehabilitation.

Torque and power of knee extensor muscles at individualized isokinetic angular velocities

OBJECTIVE

Existing isokinetic contractions are characterized using standardized angular velocities, which can induce differing adaptations. Here, we characterized the variation in the isokinetic parameters of knee extensors according to individualized angular velocity (IAV).

METHODS

We performed a cross-sectional study of 19 young, healthy men. We measured the maximum angular velocity (MAV) of concentric knee extension using the isotonic mode of an isokinetic dynamometer. Isometric and isokinetic (at angular velocities corresponding to 100%, 70%, 40%, and 10% of each individual's MAV) knee extensor contractions were performed, and the peak torque and mean power were recorded.

RESULTS

Peak torque significantly decreased with increasing IAV (129.42 ± 25.04, 84.37 ± 20.97, and 56.42 ± 16.18 Nm at 40%, 70%, and 100%, respectively), except for isometric contraction (233.36 ± 47.85) and at 10% of MAV (208 ± 48.55). At the mean power, 10% of MAV (74.52 ± 20.84 W) was significantly lower than the faster IAV (176.32 ± 49.64, 161.53 ± 56.55, and 145.95 ± 50.64 W at 40%, 70%, and 100%, respectively), and 100% was significantly lower than 40%.

CONCLUSION

The optimized IAV for isokinetic contraction to improve power output while maintaining torque is 10% to 40% of MAV. IAV may reflect both the velocity and force components of power because individuals do not have the same angular velocity.

Association between muscle strength and depression in a cohort of young adults

BACKGROUND

The study investigated the association between knee joint muscle strength and the prevalence of depression in a cohort of young adults.

METHODS

The observational, population-based study was performed with 909 participants (29.02 ± 2.03 years; 48.73% male) from the Central European Longitudinal Studies of Parents and Children: Young Adults (CELSPAC: YA), who were retained to analysis. Quadriceps and hamstring knee muscle strength were assessed by isokinetic dynamometry, and depression by Beck's Depression Inventory (BDI-II). Statistical comparisons (Mann-Whitney and Chi-squared test) and effect size analyses (Eta-Squared, and Odds Ratio) were conducted.

RESULTS

The main findings revealed an inverse association between knee joint muscle strength and depression, with individuals who had low muscle strength having 3.15 (95% CI = 2.74-3.62) times higher odds of experiencing depression. Specifically, participants with low extensor strength had 4.63 (95% CI = 2.20-9.74) times higher odds, and those with low flexor strength had 2.68 (95% CI = 1.47-4.89) times higher odds of experiencing depression compared to those individuals with high muscle strength. Furthermore, gender-specific analyses revealed that males with low muscle strength had 2.51 (95% CI = 1.53-4.14) times higher odds, while females had 3.46 (95% CI = 2.93-4.08) times higher odds of experiencing depression compared to individuals with high muscle strength.

CONCLUSIONS

Strong knee muscles seems to be a key factor in preventing depression, specially in female young adults. The results support the importance of promoting an increase in muscle strength through physical activity as a preventive strategy against depression in this population.

Changes in muscular strength following nine weeks of high- or low-load resistance training

BACKGROUND

Traditional resistance training schemes often utilize higher loads for strength gains and lower loads for muscular endurance or hypertrophy. This study aimed to investigate muscular strength adaptations after nine weeks of high- or low-load resistance training.

METHODS

Seventeen recreationally-trained male lifters were recruited for this study (age 20.4±2.7 years) and split into high-load (85% 1-RM; N.=8) or low-load (30% 1-RM; N.=9), completing three whole-body training sessions per week for nine weeks. Each session included three working sets of repetitions to failure. At baseline and every three weeks after, knee extension/flexion were tested using an isokinetic dynamometer. Participants completed three 5-s MVIC and isokinetic muscle actions at 60°/s and 120°/s, with the highest torque value used in analysis. Predicted 1-RM testing was at baseline and end of training program. ANCOVAs were conducted to analyze changes in strength, with significance set at P<0.05.

RESULTS

This study demonstrated similar MVIC and peak torque values for both isokinetic speeds, although there were nonsignificant decreases largely driven by the 30% group. The high-load group showed greater increases in 1-RM following the training program.

CONCLUSIONS

This study suggests training with lighter loads may be detrimental for long term isokinetic strength, whereas heavier loads could result in maintenance and greater increases in 1-RM despite performing repetitions to failure.

Normative Standards for Isokinetic and Anthropometric Classifications of University-Level Netball Players

CONTEXT

The purpose of the study was to develop normative ranges and standards for knee and shoulder isokinetic and anthropometric values. These standards can be qualitatively interpreted and allow practitioners to classify isokinetic and anthropometric values more objectively for university-level netball players.

DESIGN

Posttest only observational study design. All players were only evaluated once during the in-season to generate normative ranges.

METHODS

A total of 51 female players volunteered. Participants were evaluated on an isokinetic dynamometer at 60° per second to obtain knee-extensor and knee-flexor values as well as shoulder-flexor and shoulder-extensor values. A total of 16 anthropometric variables were collected including stature, body mass, 8 skinfolds, and 6 circumferences. Between-group differences were calculated to determine whether playing level was a differentiating factor in data.

RESULTS

Normative standards were developed for isokinetic parameters associated with the knee and shoulder joints as well as skinfolds and circumference measures. No statistically significant between-group differences were evident (χ2Kruskal-Wallis[2] = 3.96, P = .140).

CONCLUSION

These standards can be used by coaches and practitioners to set attainable goals for individual players or those from secondary leagues, classify individual and team-based performances, and facilitate decision-making processes.

Testing the Posterior Chain: Diagnostic Accuracy of the Bunkie Test versus the Isokinetic Hamstrings/Quadriceps Measurement in Patients with Self-Reported Knee Pain and Healthy Controls

(1) Background: The isokinetic measurement (IM) of the leg muscles is well established but costly, whereas the Bunkie Test (BT) is a rarely investigated but easy-to-conduct functional test to evaluate the total posterior chain. Although the tests differ in aim and test structures, both have their justification in the assessment process. Therefore, this study evaluated the diagnostic accuracy of the BT and the IM. (2) Methods: 21 participants (9 female, 12 male; age, 26.2 ± 5.26 years; weight 73.8 ± 14.6 kg; height 176.0 ± 9.91 cm) and 21 patients (9 female, 12 male; age, 26.5 ± 5.56 years; weight, 72.6 ± 16.9 kg; height 177.0 ± 10.1 cm) with self-reported pain in the knee performed the IM and the BT. For IM, we calculated the ratio of the knee mean flexor/extensor peak torque (H/Q ratio) for 60°/s and 120°/s, and BT performance was measured in seconds. We classified the IM (<0.6 H/Q ratio) and the BT (leg difference ≥4 s) as binary results according to the literature. We calculated the sensitivity and specificity, which we compared with the Chi-Square test, and the 95% confidence intervals (CI). A p-value of ≤0.05 is considered significant. (3) Results: The sensitivity for the BT was 0.89, 95% CI [0.67, 0.99], and the specificity was 0.52 [0.30, 0.74]. For the IM, the sensitivity was 0.14 [0.03, 0.36] for 60°/s and 0.05 [0.00, 0.24] for 120°/s, and the specificity was 0.70 [0.46, 0.88] for 60°/s and 0.90 [0.68, 0.99] for 120°/s. The results of the Chi-Square tests were significant for the BT (χ2 (1) = 6.17, p = 0.01) but not for the IM (60°/s: χ2 (1) = 0.70, p = 0.40; 120°/s: χ2 (1) = 0.00, p = 0.97). (4) Conclusions: Patients were more likely to obtain a positive test result for the BT but not for the IM.

Reliability of isokinetic decay slope is superior to using fatigue indices for shoulder horizontal abduction

INTRODUCTION

Reliable and valid measurements for shoulder muscular endurance should be available for clinical use. The posterior shoulder endurance test offers a potential clinical assessment, but its construct validity isn't available. Since a criterion measure of muscular endurance is not available, this study's purpose was to determine a reliable method for testing shoulder muscular endurance using an isokinetic dynamometer.

METHODS

The test-retest reliability, standard error measurement, and minimal detectable change were calculated on four different paradigms to quantify muscular fatigue using two isokinetic speeds (60°sec-1,180°sec-1). Calculation paradigms included peak torque fatigue index (FI), average torque FI, area-under-the-curve FI, and peak torque decay slope. Testing occurred on two days. Repeated measures analysis of variance compared the two peak torque decay slopes across both testing days.

RESULTS

Superior reliability was found within the decay slope measurements at both 60°sec-1 (ICC = 0.941) and 180°sec-1 (ICC = 0.764) speeds, with the 60°sec-1 decay slope being the highest reliability between the two angular velocities. There was a greater amount of fatigue in the 60°sec-1 decay slope compared to the 180°sec-1 decay slope.

CONCLUSION

Using the decay slope of isokinetic shoulder horizontal abduction at 60°sec-1 is a reliable method to validate other muscular endurance clinical measures. Rehabilitation specialists should utilize the decay slope of the isokinetic dynamometry to monitor responsiveness.

Exploring How Older Adult's Gender Role is Associated with Studied Outcomes Following an Outdoor Exercise Structure Program

This study aimed to describe the gender roles of people interested in an exercise program done on outdoor exercise structures and test if gender roles were associated with studied outcomes. Older adults aged 65+ who were not currently performing resistance training were invited to participate. Gender roles were quantified using the Bem Sex Role Inventory 30-item questionnaire (-60 [feminine] to +60 [masculine]). Outcomes included completing the 6-week intervention (Y/N) and changes in physical function (one leg stance, 30-s chair stand), strength (predicted maximal chest press and leg press, grip strength), power (knee extensor power), and overall health via the SF-36 questionnaire. Twenty-nine adults (65.5% female; median 72 years old) participated in the study, and 17 completed the intervention (58.6%). The median (interquartile) gender role score was -13.0 (-19.5 to -8.5), with no gender role difference (p = .62) between completers and non-completers. These results suggest that older adults interested in such a program portray themselves as more feminine. No association was found between gender role scores and changes in any study outcomes. In this setting, gender roles did not seem to impact the study outcomes and therefore may not need to be considered when designing an outdoor exercise structure program.

Resistance Training on an Outdoor Exercise Structure Improves Lower-Body Relative Strength in Older Adults

Improving relative strength is important for maintaining functionality with age, and outdoor exercise structures could be useful to facilitate this. A total of 29 adults aged 65+ participated in a non-randomized crossover study with a 6-week control followed by a 6-week resistance training intervention on an outdoor exercise structure (3x/week). Relative strength (predicted maximal leg press/lower body lean mass [Dual-energy X-ray Absorptiometry]) and physical function variables were measured at baseline, post-control, and post-intervention. Represented as median (25th-75th), lower body relative strength improved from 7.91 (7.01-9.35) post-control to 8.50 (7.99-9.72) post-intervention (p = .002) in study completers (n = 17). Maximum leg press (p = .002), 30-second chair stand (p < .001), one-leg stance (p = .011), and maximum chest press (p = .009) also improved significantly during the intervention. There were no significant changes in aerobic activity, grip strength, lean mass, or muscle power. This study demonstrates that there could be potential relative strength benefits associated with the use of outdoor exercise structures in older adults.

Equations for estimating the static supportive torque provided by upper-limb exoskeletons

Upper-limb exoskeletons are gaining traction in industrial work environments. However, other than advertised general specifications (e.g., peak support angle), the support torque provided throughout the reach envelope is largely unknown to end users. As such, this paper describes a methodology for measuring the specific supportive torque provided by upper-limb exoskeletons. The support of four commercially available passive upper-limb exoskeletons was quantified using an isokinetic dynamometer for all support ranges and levels (n = 68). Tests were repeated four times to determine between-session reliability. Intraclass correlation coefficients demonstrated 'Good' to 'Excellent' reliability, except for one condition. Polynomial regression equations were developed for each condition to predict exoskeleton support for any upper-limb elevation angle between 10° and 180°. These equations can be used to approximate upper-limb exoskeleton support in digital human modeling assessments, or to aid selection of exoskeleton settings specific to a worker's anthropometry and work task location.

Investigating The Association Between Supraspinatus Tendon Abnormality, Shoulder Pain and Isokinetic Strength in Elite Swimmers: A Cross-Sectional Study

Shoulder pain is common among elite swimmers due to the tremendous stress over shoulders during swimming. Supraspinatus muscle is one of the major prime movers and stabilizers of shoulder and is highly susceptible to overloading and tendinopathy. An understanding of the relationship between supraspinatus tendon and pain; and between supraspinatus tendon and strength would assist health care practitioners for developing training regime. The objectives of this study are to evaluate 1) the association between structural abnormality of supraspinatus tendon and shoulder pain and 2) the association between structural abnormality of supraspinatus tendon and shoulder strength. We hypothesized that structural abnormality of supraspinatus tendons positively associated with shoulder pain and negatively associated with shoulder muscle strength among elite swimmers. 44 elite swimmers were recruited from the Hong Kong China Swimming Association. Supraspinatus tendon condition was evaluated using diagnostic ultrasound imaging and shoulder internal and external rotation strength was evaluated by the isokinetic dynamometer. Pearson's R was used to study the correlation between shoulder pain and supraspinatus tendon condition and to evaluate the association between isokinetic strength of shoulders and supraspinatus tendon condition. 82 shoulders had supraspinatus tendinopathy or tendon tear (93.18%). However, there was no statistically significant association between structural abnormality of supraspinatus tendon and shoulder pain. The results showed that there was no association between supraspinatus tendon abnormality and shoulder pain and there was a significant correlation between left maximal supraspinatus tendon thickness (LMSTT) and left external rotation/ concentric (LER/Con) and left external rotation/ eccentric (LER/Ecc) shoulder strength (p < 0.05) while internal rotation/ external rotation (IR/ER) ratio can also be a significant predicator on LMSTT >6mm (R² = 0.462, F = 7.016, df = 1, p = 0.038). Structural change of supraspinatus tendon was not associated with shoulder pain, but could be a predictor on MSTT >6mm in elite swimmers.

The day-to-day reliability of residual force enhancement during voluntary and electrically stimulated contractions

Residual force enhancement (rFE) is characterized by increased steady-state isometric force following active muscle lengthening compared with a fixed-end isometric contraction at the same muscle length and level of neuromuscular activation. Many studies have characterized rFE in humans; however, the day-to-day reliability of rFE is unclear. We aimed to examine day-to-day reliability of rFE across various contraction types in the dorsiflexors in males and females. Twenty-five recreationally active young adults completed two visits, 1 week apart. Following determination of maximum voluntary contraction (MVC) strength, rFE was assessed during maximal voluntary effort, 20% MVC electrically stimulated, and 20% MVC torque-matching conditions. Each rFE condition was completed at two joint excursions: 0°-20° plantar flexion (PF) and 0°-40° PF. Intraclass correlation coefficients (ICC) assessed relative reliability and typical error of measurement (TEM), and the correlation variability of TEM (CV_TEM) assessed absolute reliability. Electrically stimulated contractions demonstrated the highest reliability at 40° PF (ICC: 0.9; CV_TEM: 22.8%) and 20° PF (ICC: 0.8; CV_TEM: 34.3%), followed by maximal voluntary contractions at 40° PF (ICC: 0.7; CV_TEM: 55.1%) and 20° PF (ICC: 0.1; CV_TEM: 81.1%). The torque-matching trials showed poor reliability for 20° and 40° PF (ICC: -0.1 to 0.3; CV_TEM: 118.1%-155.2%). Our results demonstrate higher reliability of rFE when stretching to the descending limb of the torque-angle relationship compared with the plateau region, and in electrically stimulated compared with voluntary contractions in the dorsiflexors for both males and females.

Assessment of muscle strength in para-athletes: A systematic review of observational studies

Accurate and reliable evaluation of muscle strength in para-athletes is essential for monitoring the effectiveness of strength training and/or rehabilitation programmes, and sport classification. Our aim is to synthesise evidence related to assessing muscle strength in para-athletes. Four databases were searched from January 1990 to July 2021 for observational studies focusing on strength assessment. Independent screening, data extraction, and quality assessment were performed in duplicate. A total of 1764 potential studies were identified. Thirty met the inclusion criteria and were included in the review. The mean age of participants was 30.7 years (standard deviation [SD]: 2.4). The majority were men (88%) participating in wheelchair sports, including basketball, rugby, and tennis (23/30: 76%). Overall quality varied, with more than half of the studies failing to identify strategies for dealing with confounding variables. Despite manual muscle testing being a standard component of para-sport classification systems, evidence examining strength characteristics in para-athletes is derived primarily from isometric and isokinetic testing. In studies that included comparative strength data, findings were mixed. Some studies found strength values were similar to or lower than able-bodied athletic controls. However, an important observation was that others reported higher shoulder strength in para-athletes taking part in wheelchair sports than both able-bodied and disabled non-athletes. Studies need to develop accessible, standardised strength testing methods that account for training influence and establish normative strength values in para-athletes. There is also a need for additional studies that include female para-athletes and para-athletes with greater functional impairments.

The Effect of Spinal Asymmetries on Physical Fitness Parameters in Young Elite Soccer Players

The purpose of the study was to examine the effect of spinal asymmetries on specific physical fitness parameters in young elite soccer players. Fifty male soccer players, all members of the under 17 (U17) and 15 (U15) National teams of Cyprus, were initially evaluated for thoracic kyphosis, lumbar lordosis and scoliosis asymmetries. Based on the spinal asymmetries’ initial evaluation, soccer players were categorized into the asymmetry group (AG) and normal group (NG) per spinal asymmetry. Hamstring and lower-back flexibility, countermovement jump (CMJ) and lower body isokinetic maximum force were evaluated between AG and NG. CMJ with arm swing was lower in kyphotic posture AG compared with the NG (AG: 41.70 ± 3.59 cm, NG: 44.40 ± 4.34 cm; p = 0.028). Single leg CMJ was lower in both legs in scoliotic posture AG compared with the NG (right: AG: 17.42 ± 1.86 cm, NG: 19.16 ± 2.42 cm, p = 0.008, left: AG: 17.54 ± 1.33 cm, NG: 19.97 ± 2.91 cm; p = 0.002). Sit-and-reach flexibility was lower in scoliotic posture AG (AG: 20.44 ± 5.76 cm, NG: 24.82 ± 6.83 cm; p = 0.024) and higher in lordotic posture AG (AG: 25.95 ± 6.59 cm, NG: 21.73 ± 6.45 cm; p = 0.04) both compared with the NG. No significant difference was found for quadriceps and hamstrings concentric peak torque between the AG and NG (p > 0.05). The current study revealed that kyphotic and scoliotic posture asymmetries deteriorate neuromuscular explosiveness performance and diminish lower limbs’ flexibility in young International-level soccer players.

Treatment of Knee Dislocation With Primary Repair and Suture Augmentation: A Viable Solution

Background:

Different surgical techniques have been described for the treatment of knee dislocation (KD). Nonoperative approaches are frequently combined with surgical reconstruction using auto- or allograft.

Purpose:

To evaluate the midterm results of primary surgical repair and suture augmentation to treat KD.

Study Design:

Case series; Level of evidence, 4.

Methods:

A total of 22 patients (5 women, 17 men; mean age, 45 ± 15 years) with KD were evaluated at a mean of 49 ± 16 months after surgical treatment that included primary repair and suture augmentation. Magnetic resonance imaging, stress radiographs, and outcome scores were obtained at the follow-up. Clinical examination including hop tests and force measurements for flexion and extension was performed.

Results:

The mean difference in pre- to postinjury Tegner scores was –2 ± 1. The outcome scores showed mean values of 84 ± 15 (Lysholm), 73 ± 15 (International Knee Documentation Committee) and 65 ± 25 (Anterior Cruciate Ligament–Return to Sport after Injury scale). Compared with the uninjured knee, the range of motion of the injured knee was reduced by 21° ± 12°. Twelve patients felt fit enough to perform hop tests and showed a mean deficit of 7% ± 17%° compared with the uninjured leg. The mean force deficit was 19% ± 18% for extension and 8% ± 16% for flexion. Stress radiographs revealed an 11 ± 7–mm higher anteroposterior translation on the injured side. Four patients had secondary ligament reconstructions due to persistent instability and 7 underwent arthroscopic arthrolysis due to stiffness. A significant increase of osteoarthritis was found for the medial, lateral, and patellofemoral compartments (P = .007, .004, and .006, respectively).

Conclusion:

Primary repair and suture augmentation of KD led to satisfactory clinical midterm results despite persistent radiological instability and a significant increase in osteoarthritis. This technique allows the return to activities of daily living without subjective instability in most nonathletic patients. Secondary ligament reconstructions should be performed if relevant instability persists to decrease the risk of secondary meniscal and cartilage damage.

The Effects of Step Aerobic Training on Muscle Power and Agility in Female Badminton Players

The purpose of the study was to compare the effects of step aerobic training (SAT) on muscle power and agility in female badminton players. Twenty female badminton players were assigned to experimental groups (EG = 10) were for 30 minutes 3 days a week to perform SAT (age: 16.70 ± 1.15 yrs), and control groups (CG = 10) were regular badminton training. (age: 16.60 ± 1.17 yrs). Measures of muscle power was tested with a knee extensors (KE) and knee flexors (KF) isokinetic peak toque 180°/sec (NM) and agility was tested in badminton specific movement. Results indicate that mean KE was after 4 weeks (left leg; 42.70 ± 5.65; p < 0.037, right leg; 45.90 ± 6.60; p < 0.002), KF (left leg; 40.60 ± 8.05, right leg; 41.90 ± 6.75; p < 0.001), and KE after 8 weeks (left leg; 45.00 ± 7.30, right leg; 47.30 ± 7.30; p < 0.001), KF (left leg; 45.00 ± 7.30, right leg; 47.30 ± 7.30; p < 0.001) increase than before, KE after 8 weeks (left leg; p < 0.023, right leg; p < 0.009), and KF in EG (left leg; p < 0.047, right leg; p < 0.014) increased than CG was statistically significant. Agility in EG after 4 weeks (52.42 ± 1.81 sec) and 8 weeks (49.12 ± 1.96 sec) decrease than before (55.91 ± 2.74 sec; p < 0.001). The agility time after 4 weeks (p < 0.004) and 8 weeks (p < 0.001) decreased than in the EG compared to CG. These findings indicate the 6-8 inches height of SAT and the rhythm movement control of 130-140 beats per minute (BPM) can increase muscle power and agility in 4 weeks, which is beneficial for those badminton players and coaches who want to use a short period of training.

Improvements of Physical Activity Performance and Motivation in Adult Men through Augmented Reality Approach: A Randomized Controlled Trial

The COVID-19 pandemic had a global impact, increasing the prevalence of physical inactivity, which is mostly due to the lockdown and social distancing measures adopted during the pandemic. Hence, this study aimed to compare the efficacy of augmented reality-based training on physical activity performance and motivation in healthy adults to mirror visual feedback training and conventional physical therapy. This study used the randomized control trial pretest-posttest research design. Forty-eight healthy men aged 18–35 years who were engaged in recreational physical activities were enrolled and randomly divided into four groups: augmented reality-based training reality (ART), mirror visual feedback training (MVFT), therapist-based training (TBT), and control group. The total training program was held for four weeks. The isokinetic dynamometer, sit-and-reach test, Y balance test, and the intrinsic motivation inventory-22 were used to measure the outcomes before and after the intervention. Paired sample t-test was used to compare the changes before and after the intervention within groups, while the one-way ANOVA was used for the comparison between the groups. Results of the study showed that, after four weeks of intervention, balance, muscle strength, and muscle endurance in all groups significantly improved except for the control group. The ART group showed the highest increase in muscle strength, muscle endurance, and balance compared to the other groups. The motivation level increased in all three feedback groups and was observed in the following order: ART group > MVFT group > TBT group > control group. This study highlighted the most effective method that may be applied for home training during and after this period of the pandemic. The findings revealed that training while receiving real-time feedback via AR devices improves both physical performance and motivation. Augmented reality-based training can be used as an effective training option for improving physical activity and motivation and can be suggested for home training programs.

The effects of complex decongestive therapy on pain and functionality in individuals with breast cancer who developed adhesive capsulitis due to lymphedema: an evaluation by an isokinetic computerized system

Background

This study aimed to determine the impact of complex decongestive therapy applications on upper extremity function in breast cancer patients who developed adhesive capsulitis after lymphedema.

Methods

Thirty patients who developed adhesive capsulitis due to lymphedema were divided into two groups as study (n = 15) and control (n = 15) groups. Both groups received 20 minutes of exercise five days a week for three weeks using a Biodex isokinetic dynamometer, as well as a hot pack and TENS (Transcutaneous Electrical Nerve Stimulation) treatment to the shoulder joint. The study group received 45 minutes of intensive decongestive therapy along with the adhesive capsulitis treatment. The visual analogue scale was used to assess pain, circumference, and volumetric measurements were used to assess edema, and the Arm, Shoulder, and Hand Problems Questionnaire (DASH: Disabilities of the Arm, Shoulder, and Hand) was used to assess upper extremity functionality. The shoulder range of motion was evaluated.

Results

Both groups had improvements in pain (P < 0.001), shoulder joint range of motion (P < 0.001), and upper extremity functionality (P < 0.001) after the treatment. There was a significant decrease in circumference and volumetric measurements in the study group (P < 0.001). However, no differences were seen in measurements in the control group.

Conclusions

The results showed that complex decongestive therapy was beneficial in reducing lymphedema in breast cancer patients who acquired adhesive capsulitis due to lymphedema. Consequently, the authors believe that supplementing conventional physiotherapy with complex decongestive therapy will benefit patients.

Inter-limb asymmetry in youth elite soccer players: Effect of loading conditions

The presence of inter-limb asymmetries can influence strength performance and represent an injury risk factor for team sport athletes. The present study aimed to investigate the effects of changes in resistance loads using different assessment modalities on the magnitude and the direction of inter-limb asymmetry within the same leg. Fifteen young elite soccer players from the same professional academy performed rear-foot-elevated-split-squat-test at different loading conditions (body mass with no overload, 25% of body mass, 50% of body mass 50%), isokinetic knee flexor (concentric 30°·s^-1, concentric 60°·s^-1, eccentric 90°·s^-1) and extensor (concentric 60°·s^-1, eccentric 60°·s^-1). The outcomes from the agreement analyses suggested moderate level agreement between body mass vs body mass 25% (Kappa = 0.46), with no agreement or fair agreement for the other between-assessment comparison. Our results demonstrated that the magnitude and direction of within-limb strength imbalances were inconsistent when compared within the same assessment under different resistance load conditions.

Effects of Aquatic Training and Bicycling Training on Leg Function and Range of Motion in Amateur Athletes with Meniscal Allograft Transplantation during Intermediate-Stage Rehabilitation

Meniscal allograft transplantation (MAT) is a treatment modality for restoring knee function in patients with irreversible meniscal injury. Strengthening programs to promote functional recovery are treated with caution during the intermediate rehabilitation phase following MAT. This study analyzed the effects of aquatic training (AQT) and bicycling training (BCT) during the intermediate stage of rehabilitation in amateur athletes that underwent MAT. Participants (n = 60) were divided into AQT (n = 30) and BCT (n = 30) groups. Both groups performed training three times per week from 6 to 24 weeks following surgery. International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC) score, knee joint range of motion (ROM), isokinetic knee strength, and Y-balance test (YBT) performance were evaluated. All measured variables for the AQT and BCT groups improved significantly after training compared with pre-training values. The IKDC score and YBT were significantly higher for AQT than for BCT. The knee flexion ROM and isokinetic muscle strength were significantly improved in the BCT group compared to those in the AQT group. The AQT group exhibited greater improvement in dynamic balance, whereas BCT provided greater improvement in isokinetic muscle strength. AQT and BCT were effective in reducing discomfort and improving knee symptoms and functions during intermediate-stage rehabilitation following MAT in amateur athletes.

Is There an Association in Young Patients Between Quadriceps or Hamstring Strength After ACL Reconstruction and Graft Rupture?

Background:

Younger patients who sustain anterior cruciate ligament (ACL) ruptures are at high risk for reinjury after ACL reconstruction. Restoring muscle strength before return to sports (RTS) is regarded as an important factor in reducing the reinjury risk, and quadriceps and hamstring strength assessment is commonly included in RTS testing. However, it is not clear whether reduced strength is a risk factor for subsequent graft rupture in this patient population.

Purpose:

To investigate the association between quadriceps and hamstring strength at 12 months after primary ACL reconstruction and ACL graft rupture in young patients.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

The cohort consisted of 210 patients (100 men and 110 women) who were younger than 20 years at the time of primary ACL reconstruction with a hamstring tendon autograft and who had no previous contralateral ACL injury. Isokinetic strength testing (60 and 180 deg/s) of knee flexors and extensors was performed at 12 months postoperatively, and the limb symmetry index (LSI) for each strength outcome was calculated. RTS rates and the incidence of further ACL graft ruptures were recorded.

Results:

Measures of central tendency (mean and median) of LSI values ranged from 88 to 98. The percentage of patients with LSI ≥90 was 57% to 69% for quadriceps strength and 45% to 47% for hamstring strength. Overall, 19 patients (9%) sustained an ACL graft rupture. No significant differences were found between the patients who sustained an ACL graft rupture and those who did not in terms of quadriceps and hamstring strength at 12 months. No significant associations were found between achieving LSI ≥90 for quadriceps peak torque and subsequent ACL graft rupture.

Conclusion:

In young patients who underwent an ACL reconstruction, no association was noted between quadriceps and hamstring strength at 12 months postoperatively and subsequent graft ruptures. The role of strength testing as part of the RTS criteria after ACL reconstruction, and specifically the use of limb symmetry thresholds, warrants further investigation and clarification.

Effects of High-Intensity Aquatic or Bicycling Training in Athletes with Unilateral Patellofemoral Pain Syndrome

Patellofemoral pain syndrome (PFPS) is one of the most common overuse injuries experienced by athletes. It is characterized by pain and functional deficits that lead to decreased performance, thereby limiting sports activity. Therefore, optimal training interventions are required to improve physical fitness and function while minimizing pain due to PFPS. This study aimed to compare and analyze the effects of high-intensity aquatic training (AT) and bicycling training (BT) in male athletes with PFPS. Fifty-four athletes with PFPS were divided into AT and BT intervention groups. Intervention training was conducted three times per week for 8 weeks. Cardiorespiratory fitness was evaluated using the graded exercise test (GXT) based on peak oxygen uptake (VO₂ peak), and anaerobic threshold. For the knee strength test, extension and flexion were performed and measured using isokinetic equipment. One-leg hop tests and the Y-balance test (YBT) were performed to evaluate dynamic balance, and the International Knee Documentation Committee (IKDC) scoring system was used for subjective knee evaluation. The GXT, YBT, and IKDC scores were reported according to the group and duration of the intervention. After training, VO₂ peak, YBT, knee extension strength, and IKDC score improved significantly in both the AT and BT groups compared with the pre-training values. Furthermore, the AT group exhibited significant improvement compared with the BT group. We demonstrated that AT and BT effectively improved the symptoms and muscle strength of athletes with PFPS who were only able to engage in limited high-intensity field training. AT produced a modestly better effect than BT.

Knee strength deficits following anterior cruciate ligament reconstruction differ between quadriceps and hamstring tendon autografts

PURPOSE

To compare patient reported outcomes and functional knee recovery following anterior cruciate ligament (ACL) reconstruction using either a quadriceps tendon (QT) or hamstring tendon (HT) autograft.

METHODS

Thirty-five QT patients (age 20; range 15-34 years) participated in this study and were matched for gender, age and pre-injury activity level to 70 HT (age 20; range 15-32 years) patients. The following assessments were performed at 6 and 12 months post-operatively; standardized patient-reported outcome measures (IKDC, KOOS-QOL, ACL-RSI, Marx activity, anterior knee pain), knee range of motion (passive and active), anterior knee laxity, hop tests (single and triple crossover hop for distance), and isokinetic strength of the knee extensors and flexors. All dependent variables were analysed using a two-way mixed ANOVA model, with within (Time; 6 and 12 months) and between-subject (Graft; QT and HT) factors.

RESULTS

Patient reported outcome measures and hop performance improved between 6 and 12 months (p < 0.001), however no significant differences in either patient-reported outcomes or hop performance were found between the two grafts. Isokinetic strength testing showed both groups improved their peak knee extensor strength in the operated limb between 6 and 12 months (p < 0.001), but the QT group had significantly lower knee extensor strength symmetry at both time points compared to HT at 60 deg/s (p < 0.001) and 180 deg/s (p < 0.01). In contrast, the QT group had significantly greater knee flexor strength symmetry at both time points compared to HT at 60 deg/s (p < 0.01) and 180 deg/s (p = 0.01), but knee flexor strength limb symmetry did not significantly improve over time in either group.

CONCLUSION

Recovery of knee function following either QT or HT ACL reconstruction continues between 6 and 12 months after surgery. However, knee extensor strength deficits in the QT group and knee flexor strength deficits in the HT persisted at 12 months. This may have implications for decisions regarding return to sport.

LEVEL OF EVIDENCE

III.

Validating the Cambridge Protocol: Reliability of Hip Muscle Strength Measurements Using a Motorized Dynamometer and Electromyography

BACKGROUND

Muscle weakness is common after injury in athletes and in the presence of hip pathology. It will cause abnormal hip biomechanics and can predict future injury. However, objective measurement of hip muscle strength is difficult to perform accurately and reliably. Therefore, it is challenging to determine when an athlete has returned to preinjury levels of strength. In addition, there is currently no standardized method of obtaining measurements, which prevents the data being compared or shared between research centers.

PURPOSE

The purpose of this study is to comprehensively assess the inter- and intraobserver reliability of our standardized muscle strength measurement protocol.

STUDY DESIGN

Descriptive laboratory study.

LEVEL OF EVIDENCE

Level 3, inception cohort study.

METHODS

A total of 16 healthy male volunteers (age = 28.3 ± 7.9 years) were recruited. Those with a previous history of hip injuries or disorders were excluded. These volunteers underwent strength testing according to the Cambridge Protocol on 4 separate occasions, performed by 2 independent assessors. Maximal voluntary contractions, fatigue torque fluctuations, and electromyography measurements were recorded. Intra- and interobserver reliability was assessed using intraclass correlation coefficient (ICC).

RESULTS

Good-to-excellent correlation was seen for both intra- and interobserver reliability across almost all hip movements for maximal contractions: ICC ranged 0.78 to 0.93 and 0.78 to 0.96, respectively. The standard error of the mean for all hip movements was also extremely low at 2% to 3%.

CONCLUSION

The Cambridge Protocol is a highly reliable method for objective measurement of hip muscle strength. We recommend future studies use this protocol, or the principles underpinning it, to enable data sharing and comparison across different studies.

CLINICAL RELEVANCE

This is a description and analysis of hip muscle strength measurement. If widely used, it will allow for accurate and objective strength assessment and closer monitoring of hip injuries and pathology.

Differential Effects of One Meal per Day in the Evening on Metabolic Health and Physical Performance in Lean Individuals

Background: Generally, food intake occurs in a three-meal per 24 h fashion with in-between meal snacking. As such, most humans spend more than ∼ 12-16 h per day in the postprandial state. It may be reasoned from an evolutionary point of view, that the human body is physiologically habituated to less frequent meals. Metabolic flexibility (i.e., reciprocal changes in carbohydrate and fatty acid oxidation) is a characteristic of metabolic health and is reduced by semi-continuous feeding. The effects of time-restricted feeding (TRF) on metabolic parameters and physical performance in humans are equivocal. Methods: To investigate the effect of TRF on metabolism and physical performance in free-living healthy lean individuals, we compared the effects of eucaloric feeding provided by a single meal (22/2) vs. three meals per day in a randomized crossover study. We included 13 participants of which 11 (5 males/6 females) completed the study: age 31.0 ± 1.7 years, BMI 24.0 ± 0.6 kg/m² and fat mass (%) 24.0 ± 0.6 (mean ± SEM). Participants consumed all the calories needed for a stable weight in either three meals (breakfast, lunch and dinner) or one meal per day between 17:00 and 19:00 for 11 days per study period. Results: Eucaloric meal reduction to a single meal per day lowered total body mass (3 meals/day -0.5 ± 0.3 vs. 1 meal/day -1.4 ± 0.3 kg, p = 0.03), fat mass (3 meals/day -0.1 ± 0.2 vs. 1 meal/day -0.7 ± 0.2, p = 0.049) and increased exercise fatty acid oxidation (p < 0.001) without impairment of aerobic capacity or strength (p > 0.05). Furthermore, we found lower plasma glucose concentrations during the second half of the day during the one meal per day intervention (p < 0.05). Conclusion: A single meal per day in the evening lowers body weight and adapts metabolic flexibility during exercise via increased fat oxidation whereas physical performance was not affected.

The effect of muscular strength and strength asymmetry on jumping height in soccer players

BACKGROUND: Lower limb muscular asymmetry is not well studied and may have a negative impact on performance. OBJECTIVE: To estimate how muscular strength and strength asymmetry affect jumping performance in soccer players. METHODS: Twenty-eight male professional soccer players took part in the study. The countermovement jump (CMJ) without arm swing was used to determine jumping height. Muscle strength was measured concentrically at 60 and 300∘/s. RESULTS: The peak moment of the knee extensors was positively and significantly correlated with the CMJ; r= 0.608 at 300∘/s and r= 0.489 at 60∘/s. The asymmetry of the knee flexors between the stronger and weaker leg was negatively and moderately correlated with the CMJ at 300∘/s (r=-0.396). The regression model (R2= 0.474) showed that an increase of 0.18-Nm/kg in the relative strength of the knee extensors at 300∘/s (by one SD) was related to an increase of 3-cm in the CMJ. Reducing the asymmetry of the knee flexors by 6.8 percentage points (by one SD) was related to a rise of 1.7-cm in the CMJ. CONCLUSIONS: Greater strength in the knee extensors, preferably tested at higher velocity, and reduced asymmetry in the strength of the lower hamstring muscles have a statistically significant effect on the CMJ.

Resistance Training Improves Muscle Strength and Function, Regardless of Protein Supplementation, in the Mid- to Long-Term Period after Gastric Bypass

Inadequate protein intake and low levels of physical activity are common long-term sequelae after bariatric surgery and can negatively affect muscle strength (MS) and physical function (PF). The study investigated the effects of resistance training with or without protein supplementation on MS and PF. The study, which involved a 12-week controlled trial (n = 61) of individuals 2-7 years post-Roux-en-Y gastric bypass (RYGB), comprised four groups: whey protein supplementation (PRO; n = 18), maltodextrin placebo (control [CON]; n = 17), resistance training combined with placebo (RTP; n = 11), and resistance training combined with whey protein supplementation (RTP+PRO; n = 15). An isokinetic dynamometer was used to measure MS (peak torque at 60°/s and 180°/s). PF was measured with the 30-s sit-to-stand (30-STS), 6-min walk (6-MWT), and timed up-and-go (TUG) tests. There were improvements in the absolute and relative-to-bodyweight peak torque at 60°/s and 180°/s, TUG, 6-MWT and 30-STS in the RTP and RTP+PRO groups, but not in the CON and PRO groups. Changes in MS were significantly correlated with changes in PF between the pre- and post-intervention periods. A supervised resistance training program, regardless of protein supplementation, improved MS and PF in the mid-to-long-term period after RYGB and can lead to clinical benefits and improved quality of life.

The Muscle Strength of the Knee Joint after ACL Reconstruction Depends on the Number and Frequency of Supervised Physiotherapy Visits

The aim of this study in anterior cruciate ligament reconstruction (ACLR) patients was to assess the effect of six months of supervised physiotherapy with a higher number of visits (SPHNV) compared to supervised physiotherapy with a lower number of visits (SPLNV) on the maximal peak torque (PT) and isometric torque (IT) of values obtained for hamstring (H) and quadriceps (Q) muscles of the knee joints under isokinetic and isometric conditions. Hypothesis: SPHNV improves IT and PT more than SPLNV. Group I had ACLR with a higher number of visits (n = 20), Group II had ACLR with a lower number of visits (n = 20), and Group III served as the control (n = 20). In Groups I and II, IT values were measured for quadriceps and hamstring muscles of the knee joints in the 13th and 24th weeks and for PT in the 18th and 24th weeks after ACLR (60 and 180 °/s). In group III, the measurements were taken once. The isometric torque and isokinetic peak torque values were measured in N*m and they were normalized to body mass as relative IT (RIT) and relative PT (RPT) were expressed in N*m/kg. Results: In both ACLR groups, the RIT and RPT values obtained from the operated knee joints significantly increased in the 24 weeks following ACLR compared to the uninvolved side. Group II had significantly lower RIT and RPT values for quadriceps and hamstring muscles of the operated limbs compared with the uninvolved limbs (p = 0.008, p = 0.001). In group I, the larger number of visits positively correlated with the higher PT for quadriceps and hamstring muscles of the operated and uninvolved knees (from r = 0.506; p = 0.023 too r = 0.566; p = 0.009), respectively. Six months of SPHNV positively correlated with and improved the IT and PT values in patients after ACLR much more significantly than six months of SPLNV.

Effects of Sex and Age on Quadriceps and Hamstring Strength and Flexibility in High School Basketball Athletes

BACKGROUND

Eccentric hamstring strength and hamstring/quadriceps strength ratios have been identified as modifiable risk factors of hamstring strains. Additionally, those strength and flexibility characteristics are commonly used as clinical tests to monitor progress of athletes with acute or chronic hamstring strains. Although hamstring strains are common among basketball athletes, normative values of knee strength and flexibility characteristics are scarce. Normative values for these athletes would be important in prevention and management of hamstring strains.

PURPOSE

To establish quadriceps and hamstring isokinetic strength and flexibility values among high school basketball athletes and examine the effects of sex and age.

STUDY DESIGN

Cross-sectional research.

METHODS

Isokinetic knee muscular strength (concentric quadriceps [QuadC], concentric hamstring [HamC], eccentric hamstring [HamE], and strength ratios ([HamC/QuadC and HamE/Quad]), flexibility of hip flexors and quadriceps during a Modified Thomas test, and flexibility of hip extensors and hamstring during passive straight leg raise (SLR) and passive knee extension (PKE) tests were measured. Effects of sex and age were analyzed using t-tests and analysis of variance, respectively with Bonferroni corrected post hoc tests (p≤0.01).

RESULTS

A total of 172 high school basketball athletes (64 males/108 females; mean age (range): 15.7 (14-18) years old) participated in the study. Male athletes were significantly stronger than female athletes (QuadC: p<0.001; HamC: p<0.001) while no differences were observed in strength ratio (HamC/QuadC: p=0.759-0.816; HamE/QuadC: p=0.022-0.061). Among male athletes, a significant effect of age on quadriceps and hamstring strength was observed: older male athletes were stronger than younger male athletes. Contrarily, there were no effects of age on strength among female athletes. There were significant sex differences in quadriceps flexibility, SLR, and PKE (female athletes were more flexible; p=0.001-0.005) while no sex differences were found in hip flexor flexibility (p=0.105-0.164). There were no effects of age for any flexibility variables within male and female athletes (p=0.151-0.984).

CONCLUSION

The current results provide normative values for hamstring strength and flexibility in high school basketball athletes. These normative values may further assist sports medicine specialists to develop screening tests, interventions, and return-to-sport criteria in this population.

LEVEL OF EVIDENCE

3B.

Can 3 mg·kg-1 of Caffeine Be Used as An Effective Nutritional Supplement to Enhance the Effects of Resistance Training in Rugby Union Players?

The present study uniquely examined the effect of 3 mg·kg⁻¹ chronic caffeine consumption on training adaptations induced by 7-weeks resistance training and assessed the potential for habituation to caffeine’s ergogenicity. Thirty non-specifically resistance-trained university standard male rugby union players (age (years): 20 ± 2; height (cm): 181 ± 7; body mass (kg): 92 ± 17) completed the study), who were moderate habitual caffeine consumers (118 ± 110 mg), completed the study. Using a within-subject double-blind, placebo-controlled experimental design, the acute effects of caffeine intake on upper and lower limb maximal voluntary concentric and eccentric torque were measured using isokinetic dynamometry (IKD) prior to and immediately following a resistance training intervention. Participants were split into strength-matched groups and completed a resistance-training program for seven weeks, consuming either caffeine or a placebo before each session. Irrespective of group, acute caffeine consumption improved peak eccentric torque of the elbow extensors (p < 0.013), peak concentric torque of the elbow flexors (p < 0.005), total eccentric work of the elbow flexors (p < 0.003), total concentric work of the knee extensors (p < 0.001), and total concentric and eccentric work of the knee flexors (p < 0.046) following repeated maximal voluntary contractions. Many of these acute caffeine effects were still prevalent following chronic exposure to caffeine throughout the intervention. The training intervention resulted in significant improvements in upper and lower body one-repetition maximum strength (p < 0.001). For the most part, the effect of the training intervention was equivalent in both the caffeine and placebo groups, despite a small but significant increase (p < 0.037) in the total work performed in the participants that consumed caffeine across the course of the intervention. These results infer that caffeine may be beneficial to evoke acute improvements in muscular strength, with acute effects prevalent following chronic exposure to the experimental dose. However, individuals that consumed caffeine during the intervention did not elicit superior post-intervention training- induced adaptations in muscular strength.

Could the Evaluation of Muscle Strength Imbalances Be Used as a Predictor of Total Hip Arthroplasty?

Loss of muscle strength characterizes the period before total hip arthroplasty (THA). Little is known about whether muscle strength imbalances caused by muscle strength decline could be considered another clinical predictor for THA. This study aimed to determine whether muscle imbalances may be used as a clinical predictor for THA surgery. Thirty-six participants were enrolled in the study. Eighteen patients had THA (THA group), while 18 were healthy elders (CON group). Ipsilateral (H/Q) and bilateral (% Def) muscle imbalances of the knee were assessed. THA patients showed impairment of the extensors on the affected extremity compared to those unaffected. A comparison between the groups proved there were weakened flexors in the THA group on both extremities. A comparison of the imbalances revealed a significant bilateral imbalance of the extensors and ipsilateral imbalance of both extremities in the THA group. We computed two logistic regressions using bilateral and ipsilateral imbalance as the predictors of THA surgery. We found that bilateral extensor imbalance may be used as a predictor for THA (Nagelkerke R² = 0.22). A decrease of the bilateral extensors imbalance by 8% decreases the probability of THA by 8%. The most interesting finding is that the evaluation of the bilateral extensor imbalance may be used as another clinical predictor for THA.

No Added Benefit of 8 Weeks of Shoulder External Rotation Strength Training for Youth Handball Players Over Usual Handball Training Alone: A Randomized Controlled Trial

OBJECTIVE

To assess the effectiveness of a short (5-10 minutes) shoulder external rotation (ER) strength program, using elastic bands, in adolescent handball players.

DESIGN

Randomized controlled trial.

METHODS

The sample included 6 adolescent handball teams (3 female, 3 male) with a total of 92 players and a mean age of 16.6 years. Players were randomized within teams to an intervention group, which completed a shoulder ER strengthening program of 2 exercises performed 3 times per week after handball training for 8 weeks, or a control group of no treatment. The primary outcome was the between-group difference in shoulder ER strength change, measured as isometric strength using a handheld dynamometer from preintervention to postintervention (8 weeks). Secondary outcomes were between-group differences in internal rotation (IR) strength and the ER/IR strength ratio from preintervention to postintervention.

RESULTS

The estimated between-group difference in dominant-shoulder ER strength was 0.06 N/kg (95% confidence interval [CI]: -0.01, 0.14) in favor of the intervention group. The estimated between-group differences in the ER/IR ratio and IR strength were 0.03 (95% CI: -0.02, 0.08) and 0.02 (95% CI: -0.08, 0.13), respectively.

CONCLUSION

The ER strength program improved neither the ER strength nor the ER:IR ratio. J Orthop Sports Phys Ther 2021;51(4):174-187. doi:10.2519/jospt.2021.9957.

The effectiveness of different ankle strengthening training programs on performance

BACKGROUND

The purpose of this study was to investigate the effectiveness of different ankle strengthening training programs: eccentric, concentric, and resistance bands, on performance of university level sedentary males.

METHODS

Sixty-three males between the ages of 18 and 26 years were randomized to either eccentric isokinetic (n=21), concentric isokinetic (n=21), and resistance bands ankle strengthening groups (n=21). Training was performed three days a week, for eight weeks for both sides of ankle. Each program was made progressively harder by increasing the number of repetitions or sets. Measurements evaluating strength, balance and jumping performance were repeated pre, post and at one month (follow-up) after training.

RESULTS

Statistical significance was observed for concentric evertor strength for both sides of the ankle for all groups after training (p<0.05). In addition, statistically significant increases were seen in jumping performance for all groups and dynamic balance for eccentric and concentric groups (p<0.05), with the concentric being statistically higher compared to the resistance bands group for all parameters (p<0.05).

CONCLUSIONS

Ankle isokinetic strength (eccentric, concentric) training is more effective than resistance bands regarding improvement on strength, explosive strength, and dynamic balance. Ankle isokinetic strength training, which includes evertor and invertor muscles, improves performance, especially when applied concentrically. Therefore, the proper strengthening of ankle muscles will prevent the re-injury of ankles with individuals returning to activities.

Attenuating Treatment-Related Cardiotoxicity in Women Recently Diagnosed With Breast Cancer via a Tailored Therapeutic Exercise Program: Protocol of the ATOPE Trial

OBJECTIVE

Therapeutic exercise is already used to ameliorate some of the side effects of cancer treatment. Recent studies examined its preventive potential regarding treatment-related toxicity, which can increase the risk of functional decline and lead to disease recurrence and death. This trial will examine whether the Tailored Therapeutic Exercise and Recovery Strategies (ATOPE) program, performed before treatment, can mitigate the onset and extent of cardiotoxicity beyond that achieved when the program is followed during treatment in recently diagnosed breast cancer patients.

METHODS

The intervention has a preparatory phase plus 12 to 18 sessions of tailored, high-intensity exercise, and post-exercise recovery strategies. A total of 120 women recently diagnosed with breast cancer, at risk of cardiotoxicity due to anticancer treatment awaiting surgery followed by chemotherapy and/or radiotherapy, will be randomized to either group. In a feasibility study, measurements related to recruitment rate, satisfaction with the program, adherence to them, the retention of participants, safety, and adverse effects will be explored. In the main trial, the efficacy of these interventions will be examined. The major outcome will be cardiotoxicity, assessed echocardiographically via the left ventricular ejection fraction. Other clinical, physical, and anthropometric outcomes and biological and hormonal variables will also be assessed after diagnosis, after treatment, 1 year after treatment ends, and 3 years after treatment ends.

CONCLUSION

Given its potential effect on patient survival, the mitigation of cardiotoxicity is a priority, and physical therapists have an important role in this mitigation. If the ATOPE intervention performed before treatment returns better cardioprotection results, it may be recommendable that patients recently diagnosed follow this program.

IMPACT

The ATOPE program will highlight the need for a physical therapist intervention from the moment of diagnosis, in the prevention or mitigation of cardiotoxicity, in women with breast cancer. It could help physical therapists to establish an adequate therapeutic exercise dose adapted to breast cancer patients and to propose correct therapeutic exercise prescription according to the assimilation of the sessions.

Improvements in Isokinetic Quadriceps and Hamstring Strength Testing After Focused Therapy in Patients With Flexion Instability

BACKGROUND

There is a paucity of literature to guide non-operative treatment for patients with problems after total knee arthroplasty (TKA). We sought to quantify how quadriceps and hamstring strength could improve with focused physical therapy (PT) and whether improving leg strength may prevent revision surgery for patients with flexion instability (FI) after TKA.

METHODS

This retrospective study included patients diagnosed with FI by one of the 4 fellowship-trained arthroplasty surgeons at a single academic institution. Patients with FI were referred for strength measurements and a focused PT program. In total, 166 patients completed isokinetic testing to quantify their relative quadriceps and hamstring power, torque, and work measures compared to their contralateral leg. Fifty-five (33.5%) patients subsequently completed post-PT isokinetic testing. Statistical analysis was conducted to evaluate strength deficits in the knee with FI.

RESULTS

Patients with FI were found to be 20.5%-38.4% weaker in all strength domains compared to the contralateral leg (P < .001). Patients who completed PT and pre-isokinetic and post-isokinetic testing demonstrated statistically significant gains in all extension metrics by a net range of 24.7%-34.2% (P = .011-.029) and their flexion strength metrics improved by 32.5%-40.2% (P = .002-.005). About 81.9% of patients in this subgroup did not undergo revision TKA. Those subjects who went on to revision did not statistically improve in any strength domain (P = .063-.121).

CONCLUSION

Patients with FI after TKA have significantly weaker quadriceps and hamstrings in the operative compared to contralateral leg. Patients who did not undergo revision knee arthroplasty and completed a formal PT program improved quadriceps and hamstring strength by 30%.

LEVEL OF EVIDENCE

IV (Case series).

Evaluation isometric and isokinetic of trunk flexor and extensor muscles with isokinetic dynamometer: A systematic review

OBJECTIVE

To systematically review the literature analyzing the reliability and characteristics of the protocols of isokinetic and isometric evaluation of the trunk flexor and extensor muscles with isokinetic dynamometer.

METHODS

This is a systematic review using PubMed, CENTRAL, LILACS, PEDro and SCOPUS databases, searching the oldest records up to December 2019. The risk of bias, the methodological quality and the level of evidence were evaluated using the COSMIN checklist.

RESULTS

Fourteen articles have met the criteria and have been included in this study. All the articles performed an isometric or isokinetic evaluation of the trunk muscles with the isokinetic dynamometer and presented an analysis of the protocol's reliability using the intraclass correlation coefficient. Five articles had excellent reliability (0.93-0.98). Most of the studies presented doubtful and inconsistent psychometric values for reliability, because they used a short period between tests. The level of evidence to the fourteen selected articles for reliability was moderate.

CONCLUSIONS

Although the studies present limitations in methodological quality, it was possible to identify highly reliable patterns in the parameters employed and to present recommendations for the assessment of trunk flexor and extensor muscles in the isokinetic dynamometer, both for assessment in the sitting position and orthostatic.

Measurement Properties of Isokinetic Dynamometry for Assessment of Shoulder Muscle Strength: A Systematic Review

OBJECTIVE

To investigate the evidence of measurement properties of isokinetic dynamometry (ID) for assessment of shoulder muscle strength in healthy individuals and patients with nonneurologic shoulder pathology.

DATA SOURCES

Cochrane Central Register of Controlled Trials, PubMed, EMBASE, and Physiotherapy Evidence Database were searched up to February 2020 without restrictions. Reference lists and citations were hand-searched.

STUDY SELECTION

Two review authors independently included studies that met the following criteria: (1) evaluated measurement properties of ID when used on the glenohumeral joint and (2) included individuals 18 years and older. Studies including patients with neurologic, neuromuscular, or systemic diseases or critical illness were excluded.

DATA EXTRACTION

The quality assessment and data synthesis were performed according to the COnsensus-based Standards for the selection of health Measurement INstruments methodology.

DATA SYNTHESIS

Twenty-one studies with a total of 597 participants were included. The results were combined separately for isometric, concentric, and eccentric test mode; for the velocities 30°/s-60°/s, 90°/s, 120°/s, and 240°/s; for the seated, supine, and standing position; and for internal rotation (IR), external rotation (ER), and the ER/IR ratio. The reliability of ID was overall sufficient with the majority of intraclass correlation coefficients ≥0.70. The quality of evidence was moderate or low for 20 of 30 strata examined. The measurement error results were rated as insufficient for all strata. The SEM ranged from 4%-28%. The quality of evidence varied depending of strata examined.

CONCLUSIONS

The reliability of ID for measurement of shoulder strength was overall sufficient for all positions, velocities, and modes of strength. The measurement error was not sufficient. Because most studies used the seated position, the velocities 30°/s-60°/s or 120°/s, and the concentric test mode, the quality of evidence was highest for these conditions.

Absolute and relative reliability of pain sensitivity and functional outcomes of the affected shoulder among women with pain after breast cancer treatment

OBJECTIVE

Breast cancer survivors (BCS) are often characterized by decreased pressure pain thresholds (PPT), range of motion (ROM) and strength in and around the shoulder affected by the treatment. This intra-rater reliability study was to establish the relative and absolute reliability of PPT's, active ROM and maximal isokinetic muscle strength (MIMS) of the affected shoulder in BCS with persistent pain after treatment.

METHODS

Twenty-one BCS participated in the study. The PPTs of 17 locations and pain intensity were assessed using a pressure algometer and a numeric rating scale. The ROM was measured using a universal goniometer and MIMS was measured using an isokinetic dynamometer. Relative reliability was estimated using intra class correlation coefficient (ICC), and absolute reliability using standard error of measurement (SEM). Minimum detectable change (MDC) was calculated from SEM.

RESULTS

The ICCs for PPTs ranged from 0.88-0.97, with SEM values ranging from 12.0 to 28.2 kPa and MDC ranging from 33.2 to 78.2 kPa. The ICCs for ROM ranged from 0.66-0.97, with SEM values ranging from 3.0 to 7.5° and MDC ranging from 8.4 to 20.8°. Finally, ICCs for MIMS ranged from 0.62-0.92, with SEM values ranging from 0.03 to 0.07 Nm/Kg FFM and MDC ranging from 0.09 to 0.19 Nm/kg FFM.

CONCLUSION

The results of this study indicate that PPTs, ROM and MIMS can be measured reliably on the affected shoulder in BCS with pain after treatment. This offer the possibility of using these measures to assess the effectiveness of interventions in this population.

Hop tests can result in higher limb symmetry index values than isokinetic strength and leg press tests in patients following ACL reconstruction

PURPOSE

Quadriceps weakness is a common clinical sign following anterior cruciate ligament injury and reconstruction surgery (ACLR). The aim of this study was to compare strength deficits and the limb symmetry index (LSI) from three different types of functional tests: isokinetic dynamometry, hop test, and leg press.

METHODS

A total of 26 subjects with ACLR (average 8.3 months post-operation) participated in the study. The peak knee extension torque was tested with isokinetic dynamometry at 60/180/300 °/s (ISO60/180/300). Hop distance was tested during single hop (SH) and triple hop (TH). Unilateral peak leg power (POWER) was tested during a bilateral leg press test. LSI was calculated as the ratio of the involved limb over the uninvolved limb values. Pearson correlation coefficients and paired t-tests were used to establish relationships among ISO60/180/300, SH/TH, and POWER values and compare these values between the limbs, respectively. Within-subject one-way analysis of variance (ANOVA) with post hoc analyses was used to compare LSI values among different tests.

RESULTS

ISO60/180/300 values were significantly positively correlated with SH/TH and POWER (P < 0.05), while SH/TH and POWER values were not significantly correlated. Significant limb differences were found in all tests (P = 0.001-0.008). ANOVA revealed significant LSI differences among different tests. Specifically, post hoc analyses revealed that LSI during SH was significantly higher than LSI during ISO60. Similarly, LSI during TH was significantly higher than LSIs from ISO60, ISO180, and POWER tests.

CONCLUSIONS

Peak knee extension torque values were positively associated with hop distance and leg power during the leg press test. However, LSI values should be interpreted with caution as hop tests provided significantly higher LSI values than isokinetic testing. Both isokinetic dynamometry and unilateral leg press machine could be used to isolate and strengthen the quadriceps in the involved limb. The current "gold standard" isokinetic testing at slow speed (ISO60) provided the lowest LSI value among all functional tests; therefore, the current study supported a continued use of isokinetic testing when examining individual's readiness and return-to-sport.

LEVEL OF EVIDENCE

III.

Triple Hop for Distance as a Predictor of Lower Extremity Performance in Firefighter Equipment

The objective of this study was to examine the predictive value of the Triple Hop for Distance (THD) physical performance test to assess lower extremity (LE) strength and power in individuals donning firefighter personal protective equipment (PPE). Thirty-one healthy participants completed the THD in firefighter PPE on both the dominant and non-dominant limb. Dependent variables included LE power (vertical jump height [cm]) on a jump mat, and LE strength of the quadriceps and hamstrings (peak torque [Nm]) on an isokinetic dynamometer. THD was a strong predictor of LE power on the dominant (p<0.01) and non-dominant (p<0.01) limbs. THD was also a moderate predictor of LE strength on both the dominant limb (Ham60 [p<0.01]), Quad60 [p<0.01]), and the non-dominant limb (Ham60 [p<0.01]), (Quad60 [p<0.01]). The THD was found to be a strong and valid predictor for clinical measures of LE power and strength in firefighter PPE.

Knee extensor strength and hop test performance following anterior cruciate ligament reconstruction

BACKGROUND

Knee extensor strength and single limb hop for distance have been suggested as useful measures to evaluate readiness to return to sport after anterior cruciate ligament (ACL) reconstruction. The aim of the study was to examine the association between knee extensor strength and single leg hop for distance following ACL reconstruction and to determine the proportion of patients with knee extensor strength symmetry deficits at six and 12 months.

METHODS

From December 2013 to December 2015 69 patients aged 14 to 45 undergoing primary ACL reconstruction were recruited. Isokinetic concentric knee extensor strength testing and single limb hop for distance were performed six and 12 months postoperatively. Satisfactory knee extensor strength was defined as a leg symmetry index (LSI) ≥85%.

RESULTS

At six months 27.5% (19/69) of patients had recovered satisfactory knee extensor strength in the injured leg, improving to 46.4% (32/69) at 12 months. Recovery of satisfactory strength was associated with hopping distance. Hop symmetry was achieved considerably faster than knee extensor symmetry, with 66.7% (46/69) of patients demonstrating satisfactory hopping symmetry at six months, 89.9% (62/69) at 12 months. Recovery of hopping distance was not associated with knee extensor strength.

CONCLUSIONS

Single leg hop test cannot be used as a surrogate measure for knee extensor strength as no association was found between hop tests and knee extensor strength. Less than one in three patients at six months and one in two at 12 months had recovered satisfactory knee extensor strength.

Testing a novel isokinetic dynamometer constructed using a 1080 Quantum

This study sought to assess the reliability and comparability of two custom-built isokinetic dynamometers (Model A and Model B) with the gold-standard (Humac Norm). The two custom-built dynamometers consisted of commercially available leg extension machines attached to a robotically controlled resistance device (1080 Quantum), able to measure power, force and velocity outputs. Twenty subjects (14m/6f, 26±4.8yr, 176±7cm, 74.4±12.4kg) performed concentric leg extensions on the custom-built dynamometers and the Humac Norm. Fifteen maximal leg extensions were performed with each leg at 180° s^-1, or the linear equivalent (~0.5m s^-1). Peak power (W), mean power (W), and fatigue indexes (%) achieved on all three devices were compared. Both custom-built dynamometers revealed high reliability for peak and mean power on repeated tests (ICC>0.88). Coefficient of variation (CV) and standard error of measurement (SEM) were small when comparing power outputs obtained using Model A and the Humac Norm (x¯ CV = 9.0%, x¯ SEM = 49W; peak CV = 8.4%, peak SEM = 49W). Whereas, Model B had greater variance (x¯ CV = 13.3% x¯ SEM = 120W; peak CV = 14.7%, peak SEM = 146W). The custom-built dynamometers are capable of highly reliable measures, but absolute power outputs varied depending on the leg extension model. Consistent use of a single model offers reliable results for tracking muscular performance over time or testing an intervention.