George J Davies

• DPT,MEd,PT,SCS,ATC,CSCS,FAPTA
• Professor (Full) at Georgia Southern University

Balancing of strength programming intensity with sport demands is necessary to avoid excessive workloads that could inhibit performance. To expand previous jump height focused literature, this study evaluated whether countermovement jump (CMJ) movement strategies, including eccentric characteristics, might reveal CMJ execution strategy shifts to ac...

Isokinetics is a proven method to train and objectively assess the capability of muscle groups, particularly at the knee. The current re-injury rates and less than optimal return to sport percentages seen following anterior cruciate ligament surgery highlights the need for greater focus on what tests and methods are used to make these critical deci...

The incidence of upper extremity (UE) injuries in sport, particularly with the shoulder and elbow in baseball/softball players, appears to be increasing yearly, especially in younger age athletes. Improving the objective criteria and testing methods used to determine return to play (RTP) readiness following non-operative or post-operative managemen...

Background While there have been reliability studies conducted on several upper extremity functional performance tests (UEFPT), there are several complicating factors that inhibit the ability to draw definitive consensus about the reliability of the tests in both females and males. Having reliability estimates for UEFPT in the same cohort facilitat...

Background There is lack of consensus on which tests, particularly upper extremity functional performance tests (FPT) that should be used for clinical decision making to progress a patient through a rehabilitation program or criteria for return to sport (RTS). Consequently, there is a need for tests with good psychometric properties that can be adm...

Objective: To identify which subjective and objective tests do content experts utilize to help guide return to sport (RTS) decision making for an athlete after an upper extremity (UE) injury? Methods: A modified Delphi survey was utilized, including content experts in UE rehabilitation. Survey items were identified based on a literature review i...

The incidence of knee injuries in sport, particularly involving the ACL, appears to be increasing yearly, especially in younger age athletes. Even more concerning is the frequency of ACL reinjury also appears to be increasing year after year. Improving the objective criteria and testing methods used to determine return to play (RTP) readiness follo...

Context: Typically, most clinical return to activity guidelines recommend that an injured shoulder achieve a 90% to 100% functional performance test limb symmetry index (LSI); however, as previous research demonstrated a 103% to 111% dominant limb bias in seated single-arm shot-put test (SSASPT) performance, the typical criteria might not be appro...

Background Research examining the relationship between patient reported outcomes (PRO) and upper extremity functional performance tests (UEFPT) in patients with shoulder pathology are limited. Objective To assess the relationship between the seated single arm shot put test (SSASPT) and the PRO Quick-Disabilities of Arm, Shoulder, and Hand (DASH) i...

Context: Measurements of the concentric hamstrings-quadriceps strength ratio (Hc:Qc) are almost exclusively recorded in the upright, seated position (hip flexion 80–100°) on an isokinetic dynamometer at angular velocities ranging from 30°/s to 360°/s. Further, there is a scarcity of data examining Hc:Qc ratio in females. Objective: To compare the e...

Background: Functional training and testing are an important part of a comprehensive rehabilitation program stressing the neuromuscular system in ways that simulate athletic performance to help determine criteria for return to sport. There are numerous single leg hop tests that have been used for these purposes, however, the validity and clinical...

Reliability study for the lower extremity T-Drill Hop Test.

Purpose: The aim of this work was to determine the intersession reliability and validity of a recently developed prototype Isokinetic Knee Dynamometer to assess isokinetic knee extension and flexion peak moments compared to a Biodex System 4 dynamometer. Methods: Thirty- -five healthy participants performed two sessions (48-h separation) of bila...

Context: A recent report demonstrated moderate to strong relationships between seated single-arm shot-put (SSASP) test performance and isokinetic pushing forces at varying velocities, directly supporting the SSASP test as a reflection of multijoint upper-extremity strength. Yet, no previous work appears to have assessed whether the SSASP test is m...

Objectives To compare kinematic and ground reaction force (GRF) patterns between the dominant and non-dominant limbs in males and females conducting the closed kinetic chain upper extremity stability test (CKCUEST). Design Descriptive. Setting Biomechanics laboratory. Participants Sixteen male and sixteen female healthy and physically active you...

How active muscle tendon stiffness influences markers of performance and injury risk during isotonic dynamometry and submaximal running.

Context: The shoulder complex is frequently injured during sports. The tremendous mobility of the shoulder makes returning to sport participation following shoulder injury a challenging task for both the clinician and athlete. The purpose of this clinical commentary is to review the current literature on return to sport criteria and provide eviden...

Many sport activities require explosive movements of the lower extremities. Athletes are returning back to competition following knee injuries and surgeries faster than anyone could have predicted 10 years ago. However, that has not always been in the best interest of the patient because of reinjury rates and not being able to return to the same pr...

Context: Previous investigations have examined the reliability, normalization, and underlying projection mechanics of the seated single-arm shot-put (SSASP) test. Although the test is believed to reflect test limb strength, there have been no assessments determining whether test performance is directly associated with upper-extremity strength. Ob...

Objectives: To quantify the effects of medicine ball mass (1kg, 1.5kg, 2kg) on the intensity of 90°/90° plyometric throwing exercise. Study Design: Controlled laboratory study. Setting: Biomechanics laboratory Participants: Fifteen physically active collegiate aged men Main Outcome Measures: Kinematics of the upper extremity were collected du...

Subcortical cyst formation of the proximal humerus has been suggested as a potential sign of an underlying full thickness rotator cuff tear. We present a case of a 51-year-old patient with 8 weeks of shoulder pain after a fall while playing rugby. Examination was significant for markedly reduced active range of motion, weakness of external rotation...

Determining novel isokinetic testing strategies that will ideally translate to detecting injury susceptibility and guide rehabilitation.

Background: Several researchers have investigated functional testing with regard to return to sport decision making. Change of direction activities play a role in the advancement of rehabilitation as an athlete progresses towards return to sport. Few studies have assessed tests that measure change of direction tasks. Purpose: The primary purpose o...

Subcortical cyst formation of the proximal humerus has been suggested as a potential sign of an underlying full thickness rotator cuff tear. We present a case of a 51-year-old patient with 8 weeks of shoulder pain after a fall while playing rugby. Examination was significant for markedly reduced active range of motion, weakness of external rotation...

Functional performance tests (FPTs) are tools used to assess dynamic muscle strength and power. In contrast to the lower extremity, fewer FPTs are available for the upper extremity. The seated single-arm shot put test has the potential to fill the void in upper extremity FPTs; however, the underlying mechanics have not been examined and, therefore,...

This chapter focuses on the role of isokinetics with regard to testing and training after ACL injury and reconstruction. This includes the use of isokinetics for screening, evaluation, treatment, rehabilitation, and criteria for discharge to return to sports. Specific considerations for testing after ACL reconstruction are detailed. Testing and tra...

Purpose of review: Because of the epidemiological incidence of anterior cruciate ligament (ACL) injuries, the high reinjury rates that occur when returning back to sports, the actual number of patients that return to the same premorbid level of competition, the high incidence of osteoarthritis at 5-10-year follow-ups, and the effects on the long-t...

Context: Single leg balance testing is a commonly used tool in sports medicine; however, there has been no consensus on trial duration needed to obtain reliable measures. Objective: This investigation sought to determine the minimum trial duration required to obtain the highest intrasession single and average trial reliability for single leg bal...

Because of the epidemiological incidence of anterior cruciate ligament (ACL) injuries, the high reinjury rates that occur when returning back to sports, the actual number of patients who return to the same premorbid level of competition, the high incidence of osteoarthritis at 5-10 year follow-ups and the effects on the long-term health of the knee...

Patellofemoral pain is one of the leading causes of knee pain in athletes. The many causes of patellofemoral pain make diagnosis unpredictable and examination and treatment difficult. This clinical commentary discusses a detailed physical examination routine for the patient with patellofemoral pain. Critically listening and obtaining a detailed med...

Background: Clinical examination of caspuloligamentous structures of the glenohumeral joint has historically been subjective in nature, as demonstrated by limited intra-rater and inter-rater reproducibility. Musculoskeletal diagnostic ultrasound was utilized to develop a clinically objective measurement technique for glenohumeral inferior and post...

Background: Clinical examination of caspuloligamentous structures of the glenohumeral joint has historically been subjective in nature, as demonstrated by limited intra-rater and inter-rater reproducibility. Musculoskeletal diagnostic ultrasound was utilized to develop a clinically objective measurement technique for glenohumeral inferior and poste...

Study design: Experimental randomized crossover. Objective: To determine whether sitting on a ball for 90 minutes/day instead of a chair has an effect on low back pain (LBP), low back disability, and/or core muscle endurance. Summary of background data: LBP may result from prolonged sitting. It has been proposed that replacing chairs with stab...

Background: Based on the frequency pushing and pulling patterns are used in functional activities, there is a need to establish an objective method of quantifying the muscle performance characteristics associated with these motions, particularly during the later stages of rehabilitation as criteria for discharge. While isokinetic assessment offers...

Rehabilitation of the patient with rotator cuff pathology requires a comprehensive physical examination and evidence-based rehabilitation focusing on restoring normal joint motion, scapular stabilization, and rotator cuff strength. Many patients with rotator cuff tendinitis, impingement, and partial- and full-thickness tears can return to full acti...

As knowledge regarding rehabilitation science continues to increase, exercise programs following muscu-loskeletal athletic injury continue to evolve. Rehabilitation programs have drastically changed, especially in the terminal phases of rehabilitation, which include performance enhancement, development of power, and a safe return to activity. Plyom...

In most shoulder conditions a loss of glenohumeral motion results in shoulder performance impairments. However, in the overhead athlete loss of glenohumeral internal rotation, termed glenohumeral internal rotation deficiency (GIRD), is a normal phenomenon that should be expected. Without a loss of glenohumeral internal rotation the overhead athlete...

In most shoulder conditions a loss of glenohumeral motion results in shoulder performance impairments. However, in the overhead athlete loss of glenohumeral internal rotation, termed glenohumeral internal rotation deficiency (GIRD), is a normal phenomenon that should be expected. Without a loss of gleno-humeral internal rotation the overhead athlet...

Aim: Lunges are commonly included in rehabilitation and strength training programs; however limited information regarding differences between lateral and forward lunges with varying step lengths in young adults exists. The current study compared sagittal plane joint kinematics and kinetics between forward and lateral lunges using self-selected and...

Comprehensive analysis of ankle, knee, and hip kinematics and kinetics during anterior lunge performance in young adults has not been studied. In addition, the effects of adding external resistance on the kinematics and kinetics are unknown. To determine the effects of external load on ankle, knee, and hip joint kinematics and kinetics during the a...

Clinically evaluating the scapulothoracic joint is challenging. To identify scapular dyskinesis, clinicians typically observe scapular motion and congruence during self-directed upper extremity movements. However, it is unclear whether this method is reliable. We therefore determined the interrater reliability of a scapular classification system in...

Compared with lower extremity plyometrics, data concerning the loads and intensity associated with upper extremity plyometrics are limited. The purpose of this study was to compare vertical ground reaction force (vGRF) characteristics between the clap push-up and box drop push-ups from 3.8 cm (BD1), 7.6 cm (BD2), and 11.4 cm (BD3) heights and limbs...

Much research has examined shoulder range of motion adaptations in overhead-unilateral athletes. Based on the void examining overhead-bilateral athletes, especially competitive swimmers, we examined shoulder external rotation, isolated internal rotation, composite internal rotation, and total arc of motion range of motion of competitive swimmers. T...

Understanding the relationships between performance tests and sport activity is important to the rehabilitation specialist. The purpose of this study was two- fold: 1) To identify if relationships exist between tests of upper body strength and power (Single Arm Seated Shot Put, Timed Push-Up, Timed Modified Pull-Up, and The Davies Closed Kinetic Ch...

Plyometric research in the upper extremity is limited, with the effects of open-chain plyometric exercises being studied most. Kinematic and ground reaction force data concerning closed-chain upper extremity plyometrics has yet to be examined. Twenty-one recreationally active male subjects performed four variations of plyometric push-ups in a count...

Objective documentation is needed of shoulder internal and external rotator strength using hand-held dynamometry in selected positions commonly used in a clinic. We compared strength measures and unilateral ratios between gender, limbs (dominant, nondominant), and 3 testing positions. We hypothesized that men would be stronger than women, the domin...

The purpose of this study was to examine the test-retest reliability, minimal detectable change (MDC), and determine normative values of 3 upper extremity (UE) tests of function and power. One hundred eighty participants, men (n = 69) and women (n = 111), were tested on 3 UE strength and power maneuvers in a multicenter study to determine baseline...

The primary purpose of this investigation was to compare single leg vertical jump performance and several performance characteristics derived from vertical ground reaction forces (vGRF) between the dominant (DOM) and nondominant (NDOM) legs. Secondary purposes included determining the relationship between the kinetic and temporal characteristics an...

Evaluation of the athlete with an elbow injury involves a complete upper extremity approach and a corresponding treatment approach that addresses the identified deficiencies to restore normal function. A significant focus should be placed on the proximal aspect of the upper extremity in addition to the obvious distal injury. A detailed review of th...

Scapular strength deficits have been linked to shoulder dysfunction. To establish normative data on the scapulothoracic musculature in normal subjects using a handheld dynamometer. Descriptive normative data study. Field research. 172 subjects with varying levels of overhead activity. A handheld dynamometer was used to test the upper, middle, and l...

The importance of the scapular stabilizing muscles has led to an increased interest in quantitative measurements of their strength. Few studies have measured isometric or concentric isokinetic forces. Additionally, limited reports exist on the reliability of objective measures for testing scapular protraction and retraction muscle strength or scapu...