Measures of functional performance and their association with hip and thigh strength

A practitioner's guide to isometric hip adduction and abduction test selection: Maximal force, asymmetry, and muscle activity comparisons between assessment positions

The purpose of this study was to compare maximal adduction (ADD) and abduction (ABD) force, ADD to ABD ratio (ADD:ABD), inter-limb asymmetries and muscle activity between five isometric hip strength assessment positions. Twenty male athletes performed the following positions: seated (SE), supine at knees with 0° hip flexion (SK0°) and 45° hip flexion (SK45°), and supine at ankles bilaterally (SABI) and unilaterally (SAUNI). Normalised muscle activity (%EMGmax) of adductor longus (ADDLONG), gracilis (GRAC), gluteus medius (GMED), sartorius (SAR), and lower rectus abdominis (RECABD) were also assessed. Significant main effects of assessment position were identified for relative peak force (rPF) and torque (rT), ADD:ABD, ADD asymmetry, and %EMGmax. Significantly greater ADD and ABD rPF and rT were observed in SE and SK45° compared to SABI and SAUNI. SK45° elicited the highest ADDLONG and GRAC %EMGmax during ADD, with SE and SK45° evoking the highest GMED %EMGmax during ABD. SK0° exhibited significantly higher ADD:ABD compared to all positions except SAUNI. ADD asymmetry was significantly largest in SAUNI, and RECABD %EMGmax was highest in SABI during ADD. This data can inform selection of assessment positions based on whether the primary measures of interest are maximal force and muscle activity, or identifying asymmetries.

Characterization of neuromuscular performances in adults with late-onset Pompe disease: A control case cross-sectional study

Adults with late-onset Pompe disease (aLOPD) are characterized by muscular contractile tissue deterioration. However, their neuromuscular performances are poorly known. We aimed to compare maximal muscle strength, activation, explosive strength and neuromuscular fatigue between aLOPD and controls. We studied 20 aLOPD and 20 matched controls. Isometric maximum voluntary contraction (MVC) torque was obtained for the hip, knee and ankle muscles. The voluntary activation level (VAL) during knee extensor MVC was assessed using interpolated twitch technique. Explosive strength was evaluated for knee and ankle muscles through the rate of torque development (RTD) during fast contractions. Neuromuscular fatigue was measured during a 30-second contraction of knee flexors and extensors. All muscle MVC torques were significantly lower in aLOPD than controls (p <0.05). The weakest muscles were the hip extensors followed by hip abductors and abductors. Raw value of RTD was lower in aLOPD for the majority of muscles (p <0.05). No intergroup differences were reported for normalized RTD, VAL and neuromuscular fatigue (p-values> 0.05). Our study shows that maximal strength was the only neuromuscular characteristic affected in aLOPD with a proximal-distal intensity gradient. This suggests that the surviving muscle tissue of aLOPD is as functionally efficient as that of control individuals.

Clinical Commentary: A Criteria-Based Testing Protocol for Return to Sport Post Hip Arthroscopy for Impingement

Overall, 84%-87% of athletes will return to sport following hip arthroscopy; however, some literature suggests that only 57% of athletes return to their preinjury level, and only 16.9% report optimal performance. This discrepancy may be due to a lack of consistency within the definition of return to sport as well as a lack of consistency within rehabilitation programs when determining return to sport readiness. Athletes who are returning to sport must demonstrate adequate range of motion, strength, and the ability to perform multi-directional movements without the risk of reinjury. There has yet to be a comprehensive, criteria-based, return to sport testing protocol that utilizes objective measures to ensure athletes are ready for return to sport. The goal of the authors was to create a criteria-based testing protocol for return to sport following hip arthroscopy utilizing components best supported in the literature. The following parameters were identified as key areas to assess for within a return to sport testing protocol: range of motion, strength, functional testing, self-reported outcomes including psychological readiness and time. The purpose of this clinical commentary is to propose a criteria-based testing protocol to be used following hip arthroscopy for impingement from early rehabilitation through return to previous level of sport. Criteria are presented clearly to promote objective progression through rehabilitation while still being mindful of the biological healing time required for safe and efficient progression. It is the authors' hope that in identifying and establishing a criteria-based testing protocol a higher percentage of athletes will be able to return to sport.

Level of Evidence

5.

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.

A Compound Hop Index for Assessing Soccer Players' Performance

Athletes regularly have to pass a series of tests, among which one of the most frequently used functional performance measures are single-leg hop tests. As the collected individual results of tests constitute a large amount of data, strategies to decrease the amount of data without reducing the number of performed tests are being searched for. Therefore, the study aimed to present an effective method to reduce the hop-test battery data to a single score, namely, the Compound Hop Index (CHI) in the example of a soccer team. A male, first-league soccer team performed a battery of commonly used single-leg hop tests, including single hop and triple hop for distance tests and the six-meter timed hop test. Gathered data, including Limb Symmetry Indexes of the three tests, normalized to body height for the single- and triple-hop-tests distance separately for right and left legs, and the time of the six-meter timed hop test separately for right and left legs were standardized to z-scores. Consecutively, the z-scores were averaged and formed CHI. The developed CHI represents a novel score derived from the average of z-scores that significantly reduces, clarifies, and organizes the hop performance-measures data.

Obese Youth Demonstrate Altered Landing Knee Mechanics Unrelated to Lower-Extremity Peak Torque When Compared With Healthy Weight Youth

Obese (OB) youth demonstrate altered knee mechanics and worse lower-extremity performance compared with healthy weight (HW) youth. Our objectives were to compare sagittal plane knee landing mechanics between OB and HW youth and to examine the associations of knee and hip extension peak torque with landing mechanics in OB youth. Twenty-four OB and 24 age- and sex-matched HW youth participated. Peak torque was measured and normalized to leg lean mass. Peak knee flexion angle and peak internal knee extension moment were measured during a single-leg hop landing. Paired t tests, Pearson correlation coefficients, and Bonferroni corrections were used. OB youth demonstrated worse performance and lower knee extension (OB: 12.76 [1.38], HW: 14.03 [2.08], P = .03) and hip extension (OB: 8.59 [3.13], HW: 11.10 [2.89], P = .005) peak torque. Furthermore, OB youth demonstrated lower peak knee flexion angles (OB: 48.89 [45.41 to 52.37], HW: 56.07 [52.59 to 59.55], P = .02) and knee extension moments (OB: -1.73 [-1.89 to -1.57], HW: -2.21 [-2.37 to -2.05], P = .0001) during landing compared with HW youth. Peak torque measures were not correlated with peak knee flexion angle nor internal knee extension moment during landing in either group (P > .01). OB youth demonstrated altered landing mechanics compared with HW youth. However, no associations among peak torque measurements and knee landing mechanics were present.

Clinimetric properties of the one-leg sit-to-stand test in examining unilateral lower limb muscle strength among young adults

BACKGROUND

One-leg sit-to-stand (one-leg STS) test is a new clinical test developed to measure the unilateral lower limb (LE) muscle strength among young adults. This study examined the test-retest reliability and the criterion-concurrent validity of the one-leg STS.

METHODS

Forty young adults (mean age ± SD, 28.07 ± 5.39 years) participated in the study. The one-leg STS test was administered in two separate assessment sessions to examine test-retest reliability. Two-leg STS test was administered and the performance time was measured. The concentric peak strength of hip flexors/extensors, knee flexors/extensors and ankle dorsi-flexors/plantar-flexors were determined using an isokinetic dynamometer. An intraclass correlation coefficient (ICC) was used to examine the test-retest reliability of one-leg STS test. The criterion validity of the one-leg STS test was evaluated against the performance of the two-leg STS test using an independent sample t test. The concurrent validity of the one-leg STS test was evaluated by investigating the relationships between STS performance time and LE muscle strength using Pearson correlation coefficients.

RESULTS

 The reliability analysis showed that one-leg STS performance time had excellent test-retest reliability (ICC_3,1  = 0.960, P < .001). Also, the one-leg STS performance time was not different between the first and second sessions, t (39) = 0.672, P = .506. The performance time of the one-leg STS test was significantly greater than the two-leg STS test (t (39) = 20.63, P < .001). The performance time of the one-leg STS test significantly correlated with the concentric peak strength of all LE muscles (P < .05).

CONCLUSIONS

The one-leg STS test demonstrated excellent reliability and criterion-concurrent validity against the two-leg STS and the LE muscle strength. The one-leg STS test was simple to administer and could be beneficial for the assessment of unilateral LE muscle strength of young adults in clinical settings.

Different Effects of 2 mA and 4 mA Transcranial Direct Current Stimulation on Muscle Activity and Torque in a Maximal Isokinetic Fatigue Task

Studies investigating the effects of transcranial direct current stimulation (tDCS) on fatigue and muscle activity have elicited measurable improvements using stimulation intensities ≤2 mA and submaximal effort tasks. The purpose of this study was to determine the effects of 2 mA and 4 mA anodal tDCS over the primary motor cortex (M1) on performance fatigability and electromyographic (EMG) activity of the leg muscles during a maximal isokinetic task in healthy young adults. A double-blind, randomized, sham-controlled crossover study design was applied. Twenty-seven active young adults completed four sessions, each spaced by 5-8 days. During session 1, dominance was verified with isokinetic strength testing, and subjects were familiarized with the fatigue task (FT). The FT protocol included 40 continuous maximum isokinetic contractions of the knee extensors and flexors (120°/s, concentric/concentric). During Sessions 2-4, tDCS was applied for 20 min with one of three randomly assigned intensities (sham, 2 mA or 4 mA) and the FT was repeated. The anode and cathode of the tDCS device were placed over C3 and the contralateral supraorbital area, respectively. A wireless EMG system collected muscle activity during the FT. The 2 mA tDCS condition had significantly less torque (65.9 ± 32.7 Nm) during the FT than both the sham (68.4 ± 33.9 Nm, p < 0.001) and 4 mA conditions (68.4 ± 33.9 Nm, p = 0.001). Furthermore, the 2 mA condition (33.8 ± 11.7%) had significantly less EMG activity during the FT than both the sham (39.7 ± 10.6%, p < 0.001) and 4 mA conditions (40.5 ± 13.4%, p = 0.001). Contrary to previous submaximal isometric fatigue investigations, the 2 mA tDCS condition significantly reduced torque production and EMG activity of the leg extensors during a maximal isokinetic FT compared with the sham and 4 mA conditions. Also, torque production and EMG activity in the 4 mA condition were not significantly different from sham. Thus, the effects of tDCS, and the underlying mechanisms, might not be the same for different tasks and warrants more investigation.

Increased leg muscle fatigability during 2 mA and 4 mA transcranial direct current stimulation over the left motor cortex

Transcranial direct current stimulation (tDCS) using intensities ≤ 2 mA on physical and cognitive outcomes has been extensively investigated. Studies comparing the effects of different intensities of tDCS have yielded mixed results and little is known about how higher intensities (> 2 mA) affect outcomes. This study examined the effects of tDCS at 2 mA and 4 mA on leg muscle fatigability. This was a double-blind, randomized, sham-controlled study. Sixteen healthy young adults underwent tDCS at three randomly ordered intensities (sham, 2 mA, 4 mA). Leg muscle fatigability of both legs was assessed via isokinetic fatigue testing (40 maximal reps, 120°/s). Torque- and work-derived fatigue indices (FI-T and FI-W, respectively), as well as total work performed (TW), were calculated. FI-T of the right knee extensors indicated increased fatigability in 2 mA and 4 mA compared with sham (p = 0.01, d = 0.73 and p < 0.001, d = 1.61, respectively). FI-W of the right knee extensors also indicated increased fatigability in 2 mA and 4 mA compared to sham (p = 0.01, d = 0.57 and p < 0.001, d = 1.12, respectively) and 4 mA compared with 2 mA (p = 0.034, d = 0.37). tDCS intensity did not affect TW performed. The 2 mA and 4 mA tDCS intensities increased the fatigability of the right knee extensors in young, healthy participants, potentially from altered motor unit recruitment/discharge rate or cortical hyperexcitability. Despite this increase in fatigability, the TW performed in both these conditions was not different from sham.

The Tolerability and Efficacy of 4 mA Transcranial Direct Current Stimulation on Leg Muscle Fatigability

Transcranial direct current stimulation (tDCS) modulates cortical excitability and affects a variety of outcomes. tDCS at intensities ≤2 mA is well-tolerated, but the tolerability and efficacy of tDCS at intensities >2 mA merits systematic investigation. The study objective was to determine the tolerability and effects of 4 mA tDCS on leg muscle fatigability. Thirty-one young, healthy adults underwent two randomly ordered tDCS conditions (sham, 4 mA) applied before and during an isokinetic fatigue test of the knee extensors and flexors. Subjects reported the severity of the sensations felt from tDCS. Primary outcomes were sensation tolerability and the fatigue index of the knee extensors and flexors. A repeated-measures ANOVA determined statistical significance (p < 0.05). Sensation severity at 4 mA tDCS was not substantially different than sham. However, two subjects reported a moderate–severe headache, which dissipated soon after the stimulation ended. The left knee flexors had significantly greater fatigability with 4 mA tDCS compared with sham (p = 0.018). tDCS at 4 mA was well-tolerated by young, healthy subjects and increased left knee flexor fatigability. Exploration of higher intensity tDCS (>2 mA) to determine the potential benefits of increasing intensity, especially in clinical populations with decreased brain activity/excitability, is warranted.

Prevention of Lateral Ankle Sprains

CONTEXT

Given the frequency of ankle sprains, especially in the athletic population, prevention is a primary task of athletic trainers and other sports health care professionals.

OBJECTIVE

To discuss the current evidence as it relates to prophylactic programs for the prevention of ankle sprains and to provide critical interpretation of the evidence supporting and refuting the implementation of preventive programs.

CONCLUSIONS

External prophylactic supports and preventive exercise programs are effective for reducing the risk of ankle sprains in both uninjured and previously injured populations. Ankle bracing appears to offer the best outcomes in terms of cost and risk reduction. However, there remains a paucity of well-designed, prospective randomized controlled trials relevant to the primary prevention of lateral ankle sprains, especially across a range of sport settings.

The effect of structural firefighter protective clothing systems on single-legged functional hop test scores

BACKGROUND

Firefighters must complete a physical ability test to assess work readiness. There is a lack of understanding of how personal protective clothing (PPC) affects functional performance tests for work readiness, e.g. Triple Hop for Distance (THD) and Triple Hop for Work (THW).

OBJECTIVE

To examine firefighter PPC's effect on the THD and THW measures.

METHODS

Thirty-one healthy, untrained participants (male = 20, female = 11; age = 23±3 years; height = 175.30± 11.12 cm; mass = 77.94±14.24 kg; mass in PPC = 89.14±14.68 kg) completed three successful trials of the THD on their dominant and non-dominant leg, with and without PPC. The main outcome measures included maximum and mean distances on the THD with and without PPC and THW.

RESULTS

We identified a significant decrease in THD measures (mean difference = 97.83 cm; p <  0.001) and THW measures (mean difference = -326.61J; p <  0.001) when donning PPC in the dominant leg. We identified a significant decrease in THD (mean difference = 121.48 cm; p <  0.001) and THW (mean difference = 493.15J; p <  0.001) for females, and a significant difference for THD (mean difference = 84.83 cm; p <  0.001) for males when donning PPC.

CONCLUSIONS

The addition of PPC decreased the THD and THW measures. The additional mass of the PPC required the more energy to move the same distance without the PPC.

The relationship between lower extremity swelling, quadriceps strength, and functional performance following total knee arthroplasty

BACKGROUND

The relationships between swelling after total knee arthroplasty (TKA) and quadriceps strength and functional performance are poorly understood. Therefore, the aim of this study was to examine the relationships between lower extremity swelling, measured using bioelectrical impedance assessment (SF-BIA), and quadriceps strength and timed up and go (TUG) times following TKA.

METHODS

53 participants (64 ± 9.5 y/o, 43% male) undergoing primary unilateral TKA were recruited for the longitudinal observational study with repeated measures. Quantities of swelling were examined for contribution to two and six-week outcomes of strength and TUG time using hierarchical regression controlling for age, sex, and the baseline value of the dependent variable. Swelling was assessed using bioelectrical impedance assessment and quantified as the peak level of swelling and cumulative swelling (integral) over the post-TKA time window. Maximum isometric quadriceps strength (MVIC) was measured using a electromechanical dynamometer and participant functional performance measured using the TUG.

RESULTS

Neither peak swelling nor cumulative swelling significantly contributed to the variance of two-week quadriceps strength. At six weeks, peak swelling significantly improved the variance in maximal quadriceps strength by an additional four percent (p = 0.05), while cumulative swelling did not significantly contribute. Peak swelling significantly contributed to the variance in two-week (16%) and six-week (five percent) TUG times (p < 0.05), but the cumulative swelling did not.

CONCLUSIONS

Peak swelling represents a value of post-TKA swelling that is associated with strength and function. Reducing the peak level of swelling, occurring early after surgery, may improve patient functional recovery.

LEVEL OF EVIDENCE

Level II - Prospective observational study.

CORRELATION BETWEEN ECCENTRIC TRAINING AND FUNCTIONAL TESTS IN SUBJECTS WITH RECONSTRUCTED ACL

ABSTRACT Introduction: Eccentric training and jump tests are widely used to recover and measure deficits in knee strength and functionality after anterior cruciate ligament (ACL) reconstruction. Objective: To correlate knee extension and flexion torque generated by eccentric isokinetic training, with functional jump tests in subjects with reconstructed ACL. Method: Sixteen men with unilateral ACL reconstruction were assessed before and after 12 weeks of eccentric isokinetic training of knee flexors and extensors (3×10 MVC, 2x/week) at 30°/s for extension and flexion torque (isometric; concentric and eccentric at 30 and 120°/s) and functional jump tests (single, triple, cross and figure of 8). Inter- and intra-limb pre- and post-training mean peak torque (MPT), distance and jump test times were compared along with the correlations between these variables, considering P<0.05. Results: The affected limb (AL) showed significant gain of extension and flexion torque (P<0.01) in the different test categories and velocities evaluated. In the non-affected limb (NAL), this only occurred in the eccentric category (30 and 120°/s), in the extension (P<0.01) and flexion (P<0.05 and P<0.01) torques, respectively. In the jumps, there was an increase in distance (single and triple; P<0.05) and a decrease in time (crossed and figure of 8; P<0.01), however, MPT x Jump correlations were weak (r<0.3) in the pre and post-training period in both limbs. Conclusion: Despite the gain in knee extension and flexion torque and jumping performance, the expected correlation was not satisfactory, suggesting that knee functionality involves other variables inherent to motor control. Level of Evidence IV; Type of study: Case series.

Structural and physical-functional deficits in lower limbs with fractures and treated surgically

Abstract Introduction: A fracture is a traumatic bone injury that can occur from a variety of causes. Although the repercussions of fractures on the musculoskeletal system are documented, studies with more comprehensive outcomes and later stages of injury are still scarce. Objective: To evaluate the structural and physical-functional adaptations in individuals who suffered unilateral lower limb fractures treated surgically. Methods: Thirty-two patients of both genders, aged between 18 and 59 years, with a diagnosis of unilateral fracture of the lower limb and hospital discharge of at least one year, participated in the study. The affected lower limb was compared to the healthy lower limb of all participants using the outcome measures: vastus lateral muscle thickness (ultrasonography), knee extension and flexion strength (isokinetic dynamometer), ankle dorsiflexion range of motion of the distance from the foot to the wall) and functional fitness of the lower limb (single and triple horizontal jump test). Results: Statistically significant differences were found between the limbs affected and not affected in the measurements of muscle thickness (p = 0.0001), knee extension force (p = 0.0094), dorsiflexion amplitude (p = 0.0004) and functional performance (p = 0.0094, single jump and = 0.0114, triple jump). In all significant outcomes, the values of the affected limb were smaller than that of the non-affected limb. The peak torque of the knee flexor muscles did not show a statistically significant difference between limbs (p = 0.0624). Conclusion: Individuals who have undergone a surgically treated unilateral fracture of the lower limb present important structural and physical-functional late changes in relation to the non-affected limb.

Effects of Mat Pilates on hip and knee isokinetic torque parameters in elderly women

This study aimed to analyze the effects of Mat Pilates on isokinetic torque of the lower limbs in elderly women. Fourteen elderly women (Age 62 ± 3 yr) participated in 12 weeks of Mat Pilates training (60-min sessions, 3 times per week). Repetitions increased every 4 weeks and the difficulty of exercises progressed from beginner to intermediate and advanced. Peak torque was assessed before (week -4 and week 0, considered as a control period) and after 6 and 12 weeks of a periodized Mat Pilates intervention. The results showed significant improvements (p < 0.05) in concentric and eccentric peak torque of knee flexors muscles, hip flexor and extensor muscles after 12 weeks. Mechanical work showed significant improvement (p < 0.05) for knee extensor muscles during eccentric contractions after week 12, for hip extensor muscles during concentric contractions week 12, and for flexor muscles during concentric and eccentric contractions after week 12. We conclude that the periodization of Mat Pilates induced significant improvements in multiple isokinetic torque parameters.

Knee strength ratios in competitive female athletes

Knee strength ratios are related to the movement patterns, sport-specific training and knee injuries in athletes. The purpose of this study was to determine the ratios in the concentric isokinetic strength of the hamstrings and quadriceps and the isometric strength of the knee extensors. In female basketball players (n = 14) and female volleyball players (n = 12) were evaluated: the hamstrings to quadriceps peak torque ratio (H/Q) and side-to-side peak torque ratio (TR) for hamstrings and quadriceps; the ratio of the maximal bilateral strength to the summed maximal unilateral strength (B/U) and side-to-side maximal strength ratio (SR) for knee extensors. For the H/Q values, a 2 × 2 × 3 mixed-factorial analysis of variance and Bonferroni post hoc test were computed. The H/Q values increased from 48.0 (3.9)% at 60°/s to 70.4 (7.9)% at 300°/s. Furthermore, there were significant differences in the H/Q values between 300°/s and 180°/s, 300°/s and 60°/s in basketball and volleyball athletes, and between 180°/s and 60°/s only in basketball athletes (p < .05). Significantly higher H/Q results at 60°/s demonstrated basketball players than volleyball players (p < .05). Differences in the TR and SR mean values ranged from 4.4% to 8.6% and indicated no significant side-to-side strength deficits (p > .05). In both groups, greater isometric strength developed bilaterally was found (B/U > 100%). The findings revealed the magnitude of knee strength ratios in female athletes determined by sport-specific movements in basketball and volleyball. This study highlighted the importance of the bilateral strength deficit and muscular balance between the hamstrings and quadriceps in basketball and volleyball athletes in activities related to their movement patterns and specific training.

Single-Leg Hop Test Performance and Isokinetic Knee Strength After Anterior Cruciate Ligament Reconstruction in Athletes

Background:

Isokinetic strength and hop tests are commonly used to assess athletes’ readiness to return to sport after knee surgery.

Purpose/Hypothesis:

The purpose of this study was to investigate the results of single-leg hop and isokinetic knee strength testing in athletes who underwent anterior cruciate ligament reconstruction (ACLR) upon returning to sport participation as well as to study the correlation between these 2 test batteries. The secondary purpose was to compare the test results by graft type (patellar tendon or hamstring). It was hypothesized that there would be no statistically significant limb difference in either isokinetic knee strength or single-leg hop tests, that there would be a moderate to strong correlation between the 2 test batteries, and that there would be no significant difference between graft types.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Twenty-nine high school and collegiate athletes who underwent ACLR participated in this study. At the time of return to full sport participation, a series of hop tests and knee extension/flexion isokinetic strength measurements were conducted. The results were analyzed using analysis of variance and Pearson correlation (r).

Results:

The timed 6-m hop test was the only hop test that showed a significant difference between the involved and uninvolved limbs (2.3 and 2.2 seconds, respectively; P = .02). A significant difference between limbs in knee strength was found for flexion peak torque/body weight at 180 deg/s (P = .03), flexion total work/body weight at 180 deg/s (P = .04), and flexion peak torque/body weight at 300 deg/s (P = .03). The strongest correlation between the hop tests and knee strength was found between the total distance of the hop tests and flexion total work/body weight at 300 deg/s (r = 0.69) and between the timed 6-m hop test and flexion peak torque/body weight at 300 deg/s (r = –0.54). There was no statistically significant difference in hop test performance or isokinetic knee strength between graft types.

Conclusion:

The single-leg hop tests and isokinetic strength measurements were both useful for a bilateral comparison of knee functional performance and strength. Knee flexion strength deficits and flexion-to-extension ratios seemed to be correlated with single-leg hop test performance. There was no difference in postoperative hop test performance or knee strength according to graft type.

COMPARISON OF DRY NEEDLING VS. SHAM ON THE PERFORMANCE OF VERTICAL JUMP

INTRODUCTION

Dry needling has been reported to decrease pain in subjects having myofascial trigger points, as well as pain in muscle and connective tissue.

OBJECTIVE

The purpose of the study was to compare the effects on the ability to perform a two-legged vertical jump between a group who received one bout of dry needling and a group who received one bout of a sham treatment.

METHODS

Thirty-five healthy students (19 males, 16 females) were recruited to participate in this study (mean age 22.7+/- 2.4 years). The subjects were randomly divided into two groups- dry needling (n=18) vs sham (n=17). The dry needling group received needling to four sites on bilateral gastrocnemius muscles; two at the medial head and two at the lateral head. The sham group had the four areas of the gastrocnemius muscle pressed with the tube housing the needle, but the needle was never inserted into the skin. Two-legged vertical jump was measured with chalk marks on the wall before and after the dry needling and sham treatments.

RESULTS

Analysis with a t-test indicated that the dry needling group significantly increased vertical jump height 1.2 inches over the sham group.

CONCLUSION

One bout of dry needling showed an immediate effect at significantly increasing vertical jump height in healthy, young adults. Future research is needed to determine if dry needling has any long-term effects.

LEVEL OF EVIDENCE

2b.