Single-leg Vertical Jumps Research Articles

Impact of Quadriceps Muscle Fatigue on Ankle Joint Compensation Strategies During Single-Leg Vertical Jump Landing.

This study investigates the impact of quadriceps fatigue on lower limb biomechanics during the landing phase of a single-leg vertical jump (SLJ) in 25 amateur male basketball players from Ningbo University. Fatigue was induced through single-leg knee flexion and extension exercises until task failure. Kinematic and dynamic data were collected pre-fatigue (PRF) and post-fatigue (POF) using the Vicon motion capture system and the AMTI force platform and analyzed using an OpenSim musculoskeletal model. Paired sample t-tests revealed significant changes in knee and hip biomechanics under different fatigue conditions, with knee joint angle (p < 0.001), velocity (p = 0.006), moment (p = 0.006), and power (p = 0.036) showing significant alterations. Hip joint angle (p = 0.002), moment (p = 0.033), and power (p < 0.001) also exhibited significant changes. Muscle activation and joint power were significantly higher in the POF condition, while joint stiffness was lower. These findings suggest that quadriceps fatigue leads to biomechanical adjustments in the knee and hip joints, which may increase the risk of injury despite aiding in landing stability.

Relationship Between Single-Leg Vertical Jump and Drop Jump Performance, and Return to Sports After Primary Anterior Cruciate Ligament Reconstruction Using Hamstring Graft.

After anterior cruciate ligament reconstruction (ACLR), asymmetry is likely to persist in single-leg (SL) vertical jump and drop jump performance than in SL hop distance. However, its relationship with the return to sport (RTS) remains unclear. This study aimed to determine the association between vertical jump performance after primary ACLR using hamstring tendon autograft and RTS at a pre-injury competitive level. Cross-sectional study. Patients who underwent primary ACLR using hamstring tendon autograft were recruited for this study. Participants who returned to pre-injury competition after ACLR were recruited at least eight months postoperatively. Knee condition was assessed, including joint laxity, range of motion, muscle strength, and knee pain intensity during sports activities. Performance variables were also assessed, including SL hop distance, jump height in SL vertical jump, and reactive strength index (RSI; jump height/contact time) in SL drop jump. Participants were asked to subjectively report whether they had returned to the same level of competition as pre-injury and their perceived sport performance intensity. Those who answered "Yes" to the dichotomous question and had a postoperative subjective athletic performance of > 80% were categorized into the Yes-RTS group. The primary outcome was the ability to achieve RTS at the preinjury level. Sixty-five patients (female, 35; male, 30) at 13.0 (13.0) [median (interquartile)] months after ACLR participated in this study. Thirty-nine (60%) were assigned to the Yes-RTS group. Regarding knee conditions, the No-RTS group had a significantly higher knee pain intensity, as assessed using a numerical rating scale (p<0.001, effect size -0.45). In the performance tests, the No-RTS group exhibited a significantly lower limb symmetry index of RSI during the SL drop jump compared to the Yes-RTS group (p=0.002, effect size 0.81). Patients unable to achieve RTS after primary ACLR using hamstring grafts are more likely to exhibit asymmetric performance during the SL drop jump test, suggesting the significance of assessing jump symmetry when evaluating post-ACLR rehabilitation success. 3c.

Assessing the Relationship of Psychological Sport Readiness, Single-leg Vertical Jump, and Non-Sagittal Single-Leg Hops to Quadriceps Strength After Anterior Cruciate Ligament Reconstruction.

Limitations exist with current ACLR functional testing assessments that may be mitigated by including single-leg multi-directional testing. To compare Anterior Cruciate Ligament-Return to Sport after Injury Scale (ACL-RSI) scores, limb symmetry index (LSI) of the single-leg vertical jump (SLVJ), single-leg medial rotation hop (SLMRH), single-leg lateral hop (SLLH), and isokinetic quadriceps strength between participants with an ACLR and healthy controls and assess predictors of quadriceps strength asymmetry. It was hypothesized that ACL-RSI scores and LSIs for all tests would differ between ACLR and healthy control groups and within the ACLR group a strong correlation would exist between all outcome measures and quadriceps strength. Cross-Sectional Study. Twenty-six participants with an ACLR (median 13 months after surgery) and twenty-six matched healthy controls were recruited to participate in this study. Performance was assessed via SLVJ, SLMRH, SLLH, and isokinetic quadriceps strength. Between-group comparisons were made with independent t-tests and Mann-Whitney U test. Within the ACLR group, bivariate correlation and multivariate regression analysis were performed to assess the relationship between the outcome measures and quadriceps strength asymmetry. Significant between-limb differences were only identified in the ACLR group (p< 0.05): SLVJ LSI: 88.5%, SLMRH LSI: 93.6%, SLLH LSI: 92.7%, quadriceps strength LSI 80.9% - 83.9%, which were significantly lower (p <0.05) than the healthy control group. Within the ACLR group, a moderate-strong significant (p < 0.05) correlations existed with quadriceps strength and SLVJ (r=0.44-0.65), SLMRH (r =0.43-0.83), and SLLH (r=0.54-0.63); while ACL-RSI had a weak non-significant (p > 0.05) correlation with quadriceps strength (r= 0.12-0.30). Single-leg multidirectional test LSIs were less in ACLR participants than matched healthy controls and all were directly related to quadriceps strength. Psychological readiness to return to sport was not related to quadriceps strength.

Validity and Reliability of the Orthelligent Pro Sensor for Measuring Single-Leg Vertical Jump Height in Healthy Athletic Adults.

The Orthelligent Pro sensor is a practicable, portable measuring instrument. This study assessed the validity and reliability of this sensor in measuring single-leg countermovement jumps. Fifty healthy athletic adults participated in two measurement sessions a week apart in time. They performed single-leg countermovement jumps on the force plate while wearing the Orthelligent Pro sensor on their lower leg. During the first measurement session, Tester 1 invited the participants to make three single-leg countermovement jumps; subsequently, Tester 2 did the same. For assessing the sensor's intratester reliability, Tester 1 again invited the participants to make three single-leg countermovement jumps during the second measurement session. The sensor's validity was assessed by using the force plate results as the gold standard. To determinate the agreement between two measurements, Bland-Altman plots were created. The intertester reliability (ICC = 0.99; 0.97) and intratester reliability (ICC = 0.96; 0.82) were both excellent. The validity calculated (i) on the basis of the mean value of three jumps and (ii) on the basis of the maximum value of three jumps was very high, but it showed a systematic error. Taking this error into account, physiotherapists can use the Orthelligent Pro sensor as a valid and reliable instrument for measuring the jump height of countermovement jumps.

The Relationship of Open- and Closed-Kinetic-Chain Rate of Force Development With Jump Performance Following Anterior Cruciate Ligament Reconstruction.

To determine between-limbs differences in isometric rate of force development (RFD) measured during open- (OKC) and closed-kinetic-chain (CKC) strength testing and establish which method had the strongest relationship to single-leg vertical-jump performance and knee mechanics after anterior cruciate ligament (ACL)reconstruction. Subjects (n = 19) 1 to 5years from ACL reconstruction performed isometric knee extensions (OKC), unilateral isometric midthigh pulls (CKC), and single-leg vertical jumps on the ACL-involved and -noninvolved limbs. Between-limbs differences were assessed using paired t tests, and the relationship between RFD, jump performance, and knee mechanics was assessed using correlation coefficients (r; P ≤ .05). There were significant between-limbs differences in OKC RFD (P = .008, d = -0.69) but not CKC RFD. OKC RFD in the ACL-involved limb had a strong association with jump height (r = .64, P = .003), knee-joint power (r = .72, P < .001), and peak knee-flexion angle (r = .72, P = .001). CKC RFD in the ACL-involved limb had a strong association with jump height (r = .65, P = .004) and knee-joint power (r = .67, P = .002) but not peak knee-flexion angle (r = .40, P = .09). While both OKC and CKC RFD were strongly related to jump performance and knee-joint power, OKC RFD was able to detect between-limbs RFD asymmetries and was strongly related to knee-joint kinematics. These findings indicate that isometric knee extension may be optimal for assessing RFD after ACL reconstruction.

How the multiplanar trunk resistance affects the dynamic postural control during single-leg vertical jumps in college athletes with poor movement quality

BACKGROUND: Poor movement quality of the trunk and the lower limbs as well as dynamic postural control have a strong relation with non-contact injuries in sport. Aiming to reduce the risk of injuries, training approaches using loaded jumps with trunk resistance have been proposed. AIM: To describe how a multiplanar trunk load affects the dynamic postural control and the peak vertical ground reaction force of college athletes with poor movement quality of the trunk and the lower limbs. METHOD: Center of Pressure (COP) variables and peak vertical ground reaction force of 24 female college athletes during single-leg jumps with and without a trunk resistance were compared. RESULTS: There was a significant decrease of the COP displacement (p=0.006), RMS (p=0.009) and velocity (p=0.007) in the anteroposterior direction, and an increase of the COP displacement (p=0.016), RMS (p=0.043) and velocity (p=0.043) in the mediolateral direction, with a moderate effect size. No significant difference was found in the peak vertical ground reaction force. CONCLUSION: Exercises involving multiplanar trunk resistance may negatively impact dynamic postural control in women with poor movement quality.

Limb Symmetry Index of Single-Leg Vertical Jump vs. Single-Leg Hop for Distance After ACL Reconstruction: A Systematic Review and Meta-analysis.

The limb symmetry index (LSI) is recommended as a milestone of return to play (RTP), and relying on the LSI value of a single-leg hop for distance (SLHD) test may overestimate rehabilitation status. Identifying a more reliable functional test can help to carefully make decisions for RTP. The aim was to compare the LSI value of the SLHD test with that of a single-leg vertical jump (SLVJ) test after anterior cruciate ligament reconstruction (ACLR) and determine which test provides lower LSI values. The PubMed, Web of Science, Embase, and Cochrane Library databases were searched from inception to July 2022. Observational studies with participants who had both SLHD and SLVJ tests after ACLR and LSI values of an SLHD and SLVJ were included. Disagreements were resolved after discussion between the 2 researchers. Systematic review and meta-analysis. Level 4. Data on the primary outcomes (LSI values of the SLVJ and SLHD tests) were collected. Means and standard deviations (SDs) for each variable of interest were used to calculate standardized mean differences (SMDs). A total of 12 studies met the inclusion criteria for the meta-analysis. A total of 587 patients underwent SLHD and SLVJ tests at different time points after ACLR. Compared with the SLHD test, the SLVJ test provided lower LSI values (SMD -0.42; 95% confidence interval (CI) -0.67 to -0.17). Subgroup analysis found that the SLVJ test provided a lower LSI value than the SLHD test in a specific period (approximately 7-18 months after ACLR, SMD -0.53; 95% CI -0.91 to -0.14) and a similar LSI value at other times. The SLVJ test provided lower LSI values in a specific period (7-18 months after ACLR).

Dynamic postural control in women athletes with and without nonspecific low back pain with high and low pain-related anxiety- A case-control study

BackgroundLow back pain is common among athletes and it has been shown that postural control is altered in the general population with nonspecific low back pain (NSLBP). Psychological factors may also predispose individuals to risk of altered postural control. Dynamic postural control is essential to the performance of athletes. This study aimed to compare the dynamic postural control between women athletes with and without NSLBP with high and low pain-related anxiety.MethodsForty-five female athletes (15 NSLBP with high pain-related anxiety, 15 NSLBP with low pain-related anxiety, and 15 healthy (control)) were included. Pain-related anxiety was assessed using the Pain Anxiety Symptom Scale-20 (PASS-20). Based on the cut-off score of 30 for the total score of PASS-20, NSLBP patients were classified into two groups of low and high pain-related anxiety. Participants performed double-leg vertical drop jump (DVJ) and single-leg vertical jump (SVJ) tests on a Kistler force plate (type 9260AA6, Kistler Instruments Inc, Switzerland). The total root mean square (RMS) of the center of pressure (COP), COP displacement in the anteroposterior (AP), and mediolateral (ML) directions, COP mean velocity, and time to stabilization (TTS) in vertical, AP, and total directions were extracted from COP and ground reaction force data using MATLAB software. One-way Analysis of variance (ANOVA) and Welch’s ANOVA were employed to compare the groups. In case of significant findings, post hoc tests were performed.ResultsThe results showed that during DJV, athletes with high pain-related anxiety had significantly greater TTS in all total, AP, and ML directions than other groups (P < 0.05). Also, the control group showed greater total RMS distance during DJV than either NSLBP group. However, no significant differences in TTS and COP parameters were found between the groups during SVJ (P > 0.05).ConclusionsThe findings suggest that pain-related anxiety may contribute to athletes’ postural control strategies. Therefore, it is important to consider the level of pain-related anxiety during planning postural control exercises for women athletes with NSLBP.

Can Symmetry of Single-Leg Vertical Jump Height Represent Normal Lower Limb Biomechanics of Athletes After Anterior Cruciate Ligament Reconstruction?

After anterior cruciate ligament reconstruction (ACLR), single-leg horizontal hop distance limb symmetry index (LSI) >90% is recommended as a cutoff point for safe return to sport (RTS). However, athletes after ACLR have abnormal lower limb biomechanics despite an adequate single-leg hop distance LSI, implying that athletes are at high risk of reinjury. Symmetry of single-leg vertical jump height appears to be more difficult to achieve and can be a better representation of knee function than single-leg horizontal hop distance. Athletes after ACLR with single-leg jump height LSI >90% had similar biomechanical characteristics to healthy athletes. Controlled laboratory study. Level 3. A total of 46 athletes after ACLR were divided into low jump height (LJH, jump height LSI <90%, n = 23) and high jump height (HJH, jump height LSI >90%, n = 23) groups according to symmetry of single-leg vertical jump height, while 24 healthy athletes acted as a control (CONT) group. One-way analysis of variance was used to compare the kinematic and kinetic characteristics of the LJH, HJH, and CONT groups during single-leg vertical jump. Both the LJH and HJH groups demonstrated greater limb asymmetry (lower LSI) during landing compared with the CONT group in knee extension moment (P < 0.05), peak knee flexion angle (P < 0.05), and knee power (P < 0.05). Symmetry in single-leg vertical jump height does not represent normal lower limb biomechanics in athletes after ACLR. Symmetrical jump height may not signify ideal biomechanical or RTS readiness, but single-leg vertical jump test can be used as a supplement to horizontal hop test or other functional tests to reduce the likelihood of false-negative results in the absence of detailed biomechanical evaluation.

Single-leg vertical jumping in young adults with spastic cerebral palsy

BackgroundMaximum-strength tests are commonly used to detect muscle weakness in persons with cerebral palsy (CP). Tests of explosive strength (power) in the lower extremities, such as vertical jump tests, are more uncommon but might supplement maximum-strength testing by providing additional information about motor function. Research questionIs it feasible and useful to measure single-leg vertical jumping in young adults with CP? MethodsEleven persons with spastic CP (18–30 years), able to walk without support, were compared with a reference group. Jump height and power generation in jumping were measured using a 3D motion-analysis system and force plates. Maximum strength in plantarflexors was measured on the same occasion. Data were analysed using non-parametric statistics. ResultsJump height was significantly greater in the reference group than in the group with CP, both relative to the less-involved leg of the participants with CP (p = .007) and relative to their more-involved leg (p < .001). In the group with CP, jump height was twice as great for the less-involved leg than for the more-involved leg (p = .008). Power generation at the hip joint was similar between the groups but differed for the knee and ankle joints (p = .001–.033). In the reference group, most of the power was generated at the ankle joint, while the hip was the dominant power generator for the more-involved leg in the group with CP.Muscle strength in the group with CP showed a high correlation with jump height (rho = .745, p < .001) and power generation at the ankle (rho = .780, p = .001). SignificanceThe single-leg vertical jump test proved capable of measuring jump height and power generation in participants with CP. It also identified explosive muscle weakness both relative to a reference group and between legs. Hence the jump test may provide information additional to common tests of maximal muscle strength in persons with CP.

Single leg vertical jump performance identifies knee function deficits at return to sport after ACL reconstruction in male athletes

ObjectivesVertical jump performance (height) is a more representative metric for knee function than horizontal hop performance (distance) in healthy individuals. It is not known what the biomechanical status of athletes...

Comparison of Different Functional Tests for Leg Power and Normative Bilateral Asymmetry Index in Healthy Collegiate Athletes.

BackgroundBilateral leg power is being increasingly investigated as a proxy for the recovery of muscle performance after injury. Functional tests like the single leg hop for distance (SLHD) and single leg vertical jump (SLVJ) are often used to determine symmetry and return to play (RTP) readiness. As an injury predictor, leg power is accurately measured with the Keiser Air420 seated leg press.PurposeTo measure and analyze lower leg asymmetry in healthy collegiate athletes across each test battery.MethodsEighty-eight healthy student-athletes (44 males, 44 females) across 14 varsity teams at Wake Forest University performed the SLHD, SLVJ, and the Keiser. Horizontal and vertical displacement were measured via the SLHD and SLVJ, respectively. Peak power was recorded via the Keiser Air420 leg press. Pearson correlations and repeated measures ANOVA were used to calculate associations and compare bilateral asymmetry indices (BAI) and raw scores.ResultsThere was a significant effect on each test’s raw BAI (P < 0.01). The mean absolute BAI were 5.42 ± 4.9%, 6.64 ± 4.9% and 5.36 ± 4.7% for the SLHD, SLVJ and Keiser, respectively. The SLVJ and Keiser (dominant leg r = 0.832, nondominant leg r = 0.826) were more highly correlated than the SLHD and Keiser (dominant leg r = 0.645, nondominant leg r = 0.687), all of which were statistically significant (P < 0.01).ConclusionAt the 90th percentile, healthy collegiate athletes attained <15% BAI. We recommend the implementation of a battery of tests to determine normative lower limb asymmetry. A battery of functional tests may present different asymmetry indices as opposed the 10% reference asymmetry.

Functional dimorphism and relationship between different lower extremity strength tests in young elite judokas

The present study investigated the limb symmetry index (LSI) and the relationship between different functional strength tests in young elite judokas. Seventeen males (age= 16.88±1.40 years, height= 179.00±7.00 cm, weight= 78.76±15.22 kg and BMI 24.40±3.36 kg/m2) participated in the study voluntarily. Participants were tested with single leg (SL), and triple leg (THD) hop for distance, crossover hop for distance (CHD), 6 m Timed Hop Test (6mTHT), and single-leg vertical jump (SLVJ) tests, and countermovement jump (CMJ). All SL hop tests (SLHT) were applied to both right (Rs) and left sides (Ls), while CMJ was applied as without (CMJWAS) and with arm swing (CMJAS). Paired sample t-test and Pearson correlation tests were used in statistical analyses. In all SLHTs, no statistical significance was found between Rs and Ls. However, significance was found between CMJWAS and CMJAS. There was also no significance in LSIs between all SLHTs. Correlations were found between SL, THD, CHD, VJ tests, while negative and significant correlations were found between SL, THD, CHD, VJ tests, and 6 m THT. No significance was found between SLHTs and CMJWAS and CMJAS. As a result, it was found that Rs and Ls of young judokas produced similar strength in SLHTs, while they caused differences in CMJWAS and CMJAS values; when evaluated in terms of LSI, judokas showed similar rates in all SLHTs, and these rates were within reliable ranges; SLHTs had correlations with each other, but they did not show any correlation with CMJ.

Single-leg vertical jump test as a functional test after anterior cruciate ligament reconstruction

BackgroundThe aim of this study was to identify the correlations between the single-leg vertical jump (SLVJ) test and subjective and objective tests which were used widely for determining return-to-sports (RTS) after anterior cruciate ligament reconstruction (ACLR). MethodsSeventy-five patients (29.5 ± 9.2 years) who underwent ACLR between May 2012 and Jan 2014 were included. Subjective knee scoring systems including subjective International Knee Documentation Committee (IKDC) score, Lysholm score, Tegner activity scale, and ACL-Return to Sports after Injury (ACL-RSI) scale were assessed. Objective tests were also performed. ResultsThe limb symmetry index (LSI) for SLVJ test and single-leg hop for distance (SLHD) test was 89.4 ± 14.9% and 90.7 ± 11.7%. LSI for SLVJ test was correlated to subjective IKDC scores (r = 0.26, P = 0.024), Tegner activity scale (r = 0.64, P < 0.001), ACL-RSI scale (r = 0.61, P < 0.001), LSI for SLHD (r = 0.45, P < 0.001), Co-contraction (r = −0.57, P < 0.001), Shuttle run (r = −0.52, P < 0.001), and Carioca (r = −0.54, P < 0.001) tests. In isokinetic strength tests, extensor peak torque (r = 0.30, P = 0.009) and extensor strength deficit (r = −0.41, P < 0.001) were correlated with LSI for SLVJ test. ConclusionThere were considerable correlations between SLVJ test and subjective IKDC scores, Tegner activity scale, ACL-RSI scale, isokinetic extensor muscle strength, and all other functional tests. SLVJ test could be used conveniently to determine RTS after ACLR in outpatient clinics. Level of evidenceLevel IV, case series.

Effect Of Cryotherapy To A Muscle Versus A Joint On Functional Performance

Cryotherapy is a common intervention used to treat acute and chronic injuries, and it can be used to facilitate rehabilitation exercises. A common practice in athletic training is allowing a patient to return to activity after the application of some type of cryotherapy. However, the effect of applying cryotherapy to a muscle or a joint on functional performance is unclear. PURPOSE: To investigate if cooling a muscle compared to cooling a joint affects functional performance in healthy, active individuals. METHODS: Forty-five healthy, college student volunteers (21 males; 24 females) with ages ranging from 18 to 23 years (M = 20.67; SD = 1.09) were randomly assigned to muscle (low leg) cryotherapy, joint (ankle) cryotherapy, or control (no cryotherapy) intervention for 20 minutes. After a 10 minute warm-up, subjects performed practice trials of a shuttle run and single leg vertical jump (SLVJ). Subjects performed three trials of a shuttle run (4 – 6.1 m sprints) for time, and performed three trials of a SLVJ for height measured prior to and immediately following the intervention. A mixed model ANOVA with a Bonferroni Correction was used to determine significant interactions between intervention groups and times with an alpha level of .05 for statistical significance. RESULTS: For the SLVJ, there was a significant interaction between the intervention groups and time; F(2,42)=3.349, p=0.045; however, group differences were unable to be determined. The muscle intervention group had a significant decrease in jump height between pre- (M=12.24, SD=3.61) and post-test (M=10.89, SD=3.21); p=0.01. For the shuttle run test, there were no significant interactions between group and time; F(2,42)=0.747, p=0.480. The joint (pre-M=7.43, SD=0.77; post-M=7.56, SD=0.70); p=0.036, and muscle (pre-M=7.63, SD=0.71; post-M=7.79, SD=0.78); p=0.013 intervention groups had a significant increase in run times between pre- and post-test. CONCLUSIONS: Cryotherapy application for 20 minutes to a muscle significantly decreased SLVJ height and increased shuttle run time, while, cryotherapy application for 20 minutes to a joint significantly increased shuttle run time pre-to post-test. If cryotherapy application is utilized prior to performance, a warm-up should be initiated to prevent a decrease in functional performance.

Influence of Age and Pathology on Achilles Tendon Properties During a Single-leg Jump.

Prevalence of Achilles tendinopathy increases with age leading to a weaker tendon with predisposition to rupture. Conclusive evidence of the influence of age and pathology on Achilles tendon (AT) properties remains limited, as previous studies are based on standardized isometric conditions. The study investigates the influence of age and pathology on AT properties during single-leg vertical jump (SLVJ). 10 children (C), 10 asymptomatic adults (A), and 10 tendinopathic patients (T) were included. AT elongation [mm] from rest to maximal displacement during a SLVJ on a force-plate was sonographically assessed. AT compliance [mm/N]) and strain [%] was calculated by dividing elongation by peak ground reaction force [N] and length, respectively. One-way ANOVA followed by Bonferroni post-hoc correction (α=0.05) were used to compare C with A and A with T. AT elongation (p=0.004), compliance (p=0.001), and strain were found to be statistically significant higher in C (27±3 mm, 0.026±0.006 [mm/N], 13±2%) compared to A (21±4 mm, 0.017±0.005 [mm/N], 10±2%). No statistically significant differences (p≥0.05) was found between A and T (25±5 mm, 0.019±0.004 [mm/N], 12±3%). During SLVJ, tendon responded differently in regards to age and pathology with children having the most compliant AT. Higher compliance found in healthy tendons might be considered as a protective factor against load-related injuries.

Vertical Force measures to Predict Unilateral and Bilateral Jump Height

Vertical jumps are regularly implemented in assessments of leg strength and power given the clear relationship between power and jump height. While many investigations have had various successes predicting jump height using complex methodologies, a simplistic method for identifying variables that predict jump height would prove useful to develop training programs. PURPOSE: To analyze the vertical ground reaction force during single leg vertical jumps (SLVJ) and bilateral vertical jumps (BVJ) with the aim of predicting jump height. METHODS: 17 physically active adults (9M, 8F; age = 24 ± 5yrs; mass = 71.0 ± 12.5kg; height = 1.74 ± 0.10m) performed 5 unilateral and 7 bilateral jumps with each foot on an independent force plate. Two sacral markers were tracked with an 8-camera motion capture system to determine jump height. Peak vertical ground reaction forces (vGRFs), minimum vGRFs, rate of force development, rate of force reduction, loading rate, and impulse were calculated and extracted from the propulsion and landing phases of each jump trial. All variables were entered into a stepwise regression to identify which variables predicted vertical jump height. Variables were retained if the model was statistically significant at the p<.05 and variables were extracted if the model increased to p=.10. RESULTS: A model consisting of rate of force reduction during landing, minimum vGRF during landing, peak vGRF during propulsion and the rate of force development during propulsion explained single leg jump height on the right leg (r-squared = .94+/- .02). Rate of force reduction was the only significant predictor of single leg jump height on the left leg (r-squared = .76+/- .03). Finally, bilateral jump height was explained using a combined model of peak vGRF during propulsion, minimum force during landing and the propulsive impulse (r-squared = .89+/- .03). CONCLUSIONS: This study provides evidence that jump height of SLVJ and BVJ can be accurately predicted by calculating loading rates, impulse, and extracting peak and minimum values from vertical ground reaction forces. Differences between right SLVJ and left SLVJ may result from different neural control strategies used to complete each jump. Lastly, these variables may identify aspects of jump height that could be implemented during training to improve jump performance.

The Reliability and Consistency of Instrumented Shoes During Vertical Jumping

Vertical jump height is an important measure of lower extremity power. Collection of this information during athletic practices can be difficult. As a result high technology solutions have been developed to allow for real-time data collection and feedback. However, the reliability and validity of these testing solutions need to be established. PURPOSE: To compare the between day reliability of single leg vertical jump (SLVJ) and bilateral vertical jump (BVJ) heights when measured using motion capture and instrumented shoes, and to determine the correlation between these two measures. METHODS: 20 physically active adults performed both unilateral and bilateral jumps. During the jumps each subject wore a pair of instrumented shoes that synced with a Training application to determine jump height. Two sacral markers were tracked with an 8 camera motion capture system to determine jump height. This assessment was repeated within 2-4 days. An average of 7 BVJ trials and 5 SLVJ trials were analyzed. Intraclass correlation coefficients (ICC) were calculated to examine consistency of the BVJ and SLVJ values across days for the different systems (instrumented shoes, motion capture). Correlation coefficients were calculated to compare the values between systems during the BVJ and SLVJ trials. Finally, the consistency of data collection was examined for the instrumented shoe system. RESULTS: The instrumented shoes had high between day reliability for all jump types (BVJ = 0.97, Right SLVJ = 0.93, Left SLVJ = 0.97) as did the motion capture assessment (BVJ = 0.91, Right SLVJ = 0.91, and Left SLVJ = 0.93). Correlation coefficients between the instrumented shoe and motion capture were also high, with the bilateral jump (r = 0.89-0.95) being more highly correlated when compared with the unilateral jumps (r = 0.74-0.89). The instrumented shoe consistently collected the BVJ trials (99%), however the consistency was noticeably lower during the SLVJ trials (46-51%). CONCLUSIONS: The findings from this study provide evidence that SLVJ and BVJ measures as collected with instrumented shoes are reliable across days and are correlated with motion capture jump height. Therefore, the shoes can provide a reliable and valid measure of field based vertical jump testing however data was only consistently captured during the bilateral jumping tasks.

Normative Data and the Influence of Age and Gender on Power, Balance, Flexibility, and Functional Movement in Healthy Service Members

Determine the influence of age and sex and describe normative data on field expedient tests associated with power, balance, trunk stability, mobility, and functional movement in a military population. Participants (n = 247) completed a series of clinical and functional tests, including closed-chain ankle dorsiflexion (DF), Functional Movement Screen (FMS), Y-Balance Test Lower Quarter (YBT-LQ), Y-Balance Test Upper Quarter (YBT-UQ), single leg vertical jump (SLVJ), 6-m timed hop (6-m timed), and triple hop. Descriptive statistics were calculated. Analysis of variance tests were performed to compare the results based on sex and age (<30 years, >30 years). Service members demonstrated DF of 34.2 ± 6.1°, FMS composite score of 16.2 ± 2.2, YBT-LQ normalized composite score of 96.9 ± 8.6%, YBT-UQ normalized composite score of 87.6 ± 9.6%, SLVJ of 26.9 ± 8.6 cm, 6-m hop of 2.4 ± 0.5 seconds, and a triple hop of 390.9 ± 110.8 cm. Men performed greater than women (p < 0.05) on the YBT-LQ, YBT-UQ, SLVJ, 6-m timed, and triple hop. Those <30 years of age performed better than older participants (p < 0.05) on the DF, FMS, YBT-LQ, SLVJ, 6-m hop, and triple hop. Findings provide normative data on military members. Men performed better on power, balance, and trunk stability tests, whereas younger individuals performed better on power, balance, mobility, and functional movement.

Correlation of single leg vertical jump, single leg hop for distance, and single leg hop for time

Objectives To determine the correlation among three functional tests: single leg vertical jump (SLVJ), single leg hop for distance (SLHD), and single leg hop for time (SLHT). Design Prospective correlational investigation. Setting University research laboratory. Participants Forty healthy men ( n = 19) and women ( n = 21) between the ages of 18 and 30 (23.9 ± 2.0 years). Main outcome measures SLVJ was measured using the Vertec. SLHD was measured using a standard tape measure. SLHT was measured over a 10-m course using a standard stopwatch. Results The strongest correlation was between SLHT and SLHD, −0.89 and −0.89 for dominant and non-dominant lower extremities (LE), respectively. The weakest pairwise correlation was between SLVJ and SLHT, −0.71 and −0.63 for dominant and non-dominant LE, respectively. The correlation between SLVJ and SLHD was 0.74 and 0.71 for dominant and non-dominant LE, respectively. Conclusion There is a strong correlation between SLHT and SLHD, suggesting that each test measures similar constructs of function, while the modest correlation between SLVJ and SLHT suggest these two tests do not measure the same functional components, and could be paired as outcome measures for the clinical assessment of lower extremity function.