Lee Herrington

Position statement on youth resistance training: the 2014 International Consensus

The current manuscript has been adapted from the official position statement of the UK Strength and Conditioning Association on youth resistance training. It has subsequently been reviewed and endorsed by leading professional organisations within the fields of sports medicine, exercise science and paediatrics. The authorship team for this article was selected from the fields of paediatric exercise science, paediatric medicine, physical education, strength and conditioning and sports medicine.

A comparison of Star Excursion Balance Test reach distances between ACL deficient patients and asymptomatic controls

ACL injury has been associated with a decrease in proprioceptive performance and specifically postural control. Tests of postural control have been criticised for not being sufficiently challenging. The Star Excursion Balance Test (SEBT) has been proposed to offer sufficient challenge to be a sensitive test for detecting performance deficits related to pathology. The purpose of this study was to determine if decrements SEBT reach distance is associated with ACL deficiency (ACLD). Twenty five ACLD patients ACLD (17 male and 8 female, mean age 30 (SD 4.5) years) and twenty five matched controls were examined carrying out the SEBT. Factorial ANOVA showed the main effects of limb (p=0.006) and direction (p<0.001) and interaction of limb and direction (p=0.015) all had significant differences between the groups. Further analysis revealed significant differences between the control group and the ACLD limb for the limb movement directions of anterior (p=0.0032), lateral (p=0.005), posterior-medial (p=0.0024) and medial (p=0.001). There were also significant differences between the control limbs and uninjured limb of the patients for the directions of medial (p=0.001) and lateral (p=0.001). ACLD patients appear to have deficiencies in their dynamic postural control when compared to normal asymptomatic subjects. Interestingly, in the ACLD patients, their uninjured leg show deficits compared to the control in two of the four directions the ACLD leg was deficient, this may be indicative of a postural control deficit in these patients, which may have predisposed to the ACL injury and would warrant further study.

A comparison of eccentric isokinetic torque production and velocity of knee flexion angle during step down in patellofemoral pain syndrome patients and unaffected subjects

OBJECTIVE To determine knee angular velocity changes during stair descent and slow velocity eccentric isokinetic quadriceps contraction, in normal controls and patellofemoral pain syndrome patients. DESIGN Isokinetic and kinematic analysis of the performance of patellofemoral pain syndrome patients and matched normal controls. BACKGROUND In the presence of increased patellofemoral joint stresses, patellofemoral pain syndrome patients have been shown to adopt compensatory strategies to minimise joint loading and therefore pain. One of the compensatory strategies reported, is that of the break phenomena, which results in a change quadriceps torque production. METHODS Twenty female patients with patellofemoral pain syndrome and 20 asymptomatic matched controls participated in the study. All subjects had their isokinetic eccentric and concentric quadriceps torque assessed at 30 degrees/second and 2-dimensional video data taken when descending from a step. Variations in knee angular velocity and torque curves were then identified. RESULTS None of the subjects demonstrated a break on isokinetic concentric quadriceps contraction. Of the patellofemoral pain syndrome patients, 50% (10 out of 20) had a break in eccentric torque curve on testing, compared with 15% (3 out of 20) of the controls. Abnormal curve perturbation was demonstrated to occur in none of the controls isokinetically, but 20% (4 out 20) of the patellofemoral pain syndrome patients had perturbations in their torque curves. On stair decent a break was seen in 60% (12 out of 20) of the patellofemoral pain syndrome patients and 15% (3 out of 20) of the control subjects on analysis of the knee angular velocity. Twenty percent (4 out of 20) of the patellofemoral pain syndrome patients and 10% (2 out of 20) of the controls had abnormal curve perturbation on analysis of their stair descent. CONCLUSIONS The implications are that there appears to be a relationship between patellofemoral pain syndrome and control of eccentric quadriceps contraction. This relationship is possibly related to joint and soft tissue loading not just the degree of pain, with the break being a saving reflex to prevent further stress. RELEVANCE Exercise to rehabilitate the quadriceps in patellofemoral pain syndrome should be chosen with regard to joint loading and range of movement as well as velocity of contraction, in order to facilitate quadriceps activation as opposed to inhibiting it.

Changes in muscle strength and pain in response to surgical repair of posterior abdominal wall disruption followed by rehabilitation

Background: Posterior abdominal wall deficiency (PAWD) is a tear in the external oblique aponeurosis or the conjoint tendon causing a posterior wall defect at the medial end of the inguinal canal. It is often known as sportsman’s hernia and is believed to be caused by repetitive stress. Objective: To assess lower limb and abdominal muscle strength of patients with PAWD before intervention compared with matched controls; to evaluate any changes following surgical repair and rehabilitation. Methods: Sixteen subjects were assessed using a questionnaire, isokinetic testing of the lower limb strength, and pressure biofeedback testing of the abdominals. After surgery and a six week rehabilitation programme, the subjects were re-evaluated. A control group were assessed using the same procedure. Results: Quadriceps and hamstrings strength was not affected by this condition. A deficit hip muscle strength was found on the affected limb before surgery, which was significant for the hip flexors (p = 0.05). Before surgery, 87% of the patients compared with 20% of the controls failed the abdominal obliques test. Both the injured and non-injured sides had improved significantly in strength after surgery and rehabilitation. The strength of the abdominal obliques showed the most significant improvement over the course of the rehabilitation programme. Conclusions: Lower limb muscle strength may have been reduced as the result of disuse atrophy or pain inhibition. Abdominal oblique strength was deficient in the injured patients and this compromises rotational control of the pelvis. More sensitive investigations (such as electromyography) are needed to assess the link between abdominal oblique function and groin injury.

The Effect of a Neoprene Sleeve on Knee Joint Position Sense

The aims of the study were, first, to assess the effect of a neoprene knee brace on proprioceptive acuity of normal subjects and, second, to assess the relationships between a variety of tests of proprioceptive acuity. Twenty healthy, physically active subjects had absolute error scores measured while carrying out three different established tests of proprioceptive ability (active tracking, active reproduction, and perceived angle tests) under two conditions, either with or without the presence of a neoprene sleeve. The neoprene sleeve significantly improved the degree of error scores in all tests. For the active tracking, test accuracy was improved by 28% (p = 0.004), the angle reproduction test showed a 23% increase in accuracy (p = 0.029), and the accuracy of the perceived angle test improved by 27% (p = 0.035). The relationship between magnitude of error scores between the test all showed nonsignificant low correlation. The findings of this study support the previous literature, which indicates that the application of a knee sleeve improves proprioceptive acuity. The study also indicates that when testing proprioceptive acuity, a test battery should be used because of the limited correlation between any of the tests used.

Variation in Pelvic Morphology May Prevent the Identification of Anterior Pelvic Tilt

Abstract Pelvic tilt is often quantified using the angle between the horizontal and a line connecting the anterior superior iliac spine (ASIS) and the posterior superior iliac spine (PSIS). Although this angle is determined by the balance of muscular and ligamentous forces acting between the pelvis and adjacent segments, it could also be influenced by variations in pelvic morphology. The primary objective of this anatomical study was to establish how such variation may affect the ASIS-PSIS measure of pelvic tilt. In addition, we also investigated how variability in pelvic landmarks may influence measures of innominate rotational asymmetry and measures of pelvic height. Thirty cadaver pelves were used for the study. Each specimen was positioned in a fixed anatomical reference position and the angle between the ASIS and PSIS measured bilaterally. In addition, side-to-side differences in the height of the innominate bone were recorded. The study found a range of values for the ASIS-PSIS of 0–23 degrees, with a mean of 13 and standard deviation of 5 degrees. Asymmetry of pelvic landmarks resulted in side-to-side differences of up to 11 degrees in ASIS-PSIS tilt and 16 millimeters in innominate height. These results suggest that variations in pelvic morphology may significantly influence measures of pelvic tilt and innominate rotational asymmetry.

Knee valgus angle during single leg squat and landing in patellofemoral pain patients and controls

BACKGROUND Patellofemoral pain (PFP) is a commonly presenting disorder of the lower limb, frequently effecting young physically active individuals particularly females. The condition has been associated with poor control of limb alignment while undertaking unilateral limb loading tasks. This poor alignment of the limb is believed to alter loading stress within the patellofemoral joint. This study aims to investigate the degree of knee valgus, assessed as 2D frontal plane projection angle (FPPA) during single leg squatting (SLS) and hop landing (SLL) tasks in patients with PFP and compare their performance to controls and the uninjured limb. METHOD Twelve female subjects with unilateral PFP formed the patient group and thirty asymptomatic females formed the control group. They had their 2D frontal plane projection angle (FPPA) assessed during single leg squatting (SLS) and hop landing (SLL) tasks. RESULTS In the asymptomatic control group the mean FPPA for SLS was 8.4±5.1° and SLL had a mean FPPA of 13.5±5.7°. In the PFP group the mean FPPA for SLS was 16.8±5.4° and SLL had a mean FPPA of 21.7+/-3.6°, these differences were significant (p<0.01) for both tasks. CONCLUSION Patients with PFP have a greater degree of knee valgus on unilateral limb loading task than either their contralateral asymptomatic limb or an asymptomatic control group. If not corrected this may lead to further PFJ stress and ongoing morbidity.

Task based rehabilitation protocol for elite athletes following Anterior Cruciate ligament reconstruction: a clinical commentary

Anterior Cruciate ligament (ACL) injuries are one of the most common and devastating knee injuries sustained whilst participating in sport. ACL reconstruction (ACLR) remains the standard approach for athletes who aim to return to high level sporting activities but the outcome from surgery is not assured. Secondary morbidities and an inability to return to the same competitive level are common following ACLR. One factor which might be linked to these sub-optimal outcomes may be a failure to have clearly defined performance criteria for return to activity and sport. This paper presents a commentary describing a structured return to sport rehabilitation protocol for athletes following ACLR. The protocol was developed from synthesis of the available literature and consensus of physiotherapists and strength and conditioning coaches based in the home country Institute of Sports within the United Kingdom.

An evidence-based review of current perceptions with regard to the subacromial space in shoulder impingement syndromes: Is it important and what influences it?

BACKGROUND Reduction of the subacromial space as a mechanism in the etiology of shoulder impingement syndromes is debated. Although a reduction in this space is associated with shoulder impingement syndromes, it is unclear if this observation is cause or consequence. METHOD The purposes of this descriptive review are to provide a broad perspective on the current perceptions with regard to the pathology and pathomechanics of subacromial and internal impingement syndromes, consider the role of the subacromial space in impingement syndromes, describe the intrinsic and extrinsic mechanisms considered to influence the subacromial space, and critique the level of evidence supporting these concepts. FINDING Based on the current evidence, the hypothesis that a reduction in subacromial space is an extrinsic cause of impingement syndromes is not conclusively established and the evidence permits no conclusion. INTERPRETATION If maintenance of the subacromial space is important in impingement syndromes regardless of whether it is a cause or consequence, research exploring the correlation between biomechanical factors and the subacromial space, using the later as the outcome measure, would be beneficial.

Knee Valgus Angle During Landing Tasks in Female Volleyball and Basketball Players

Herrington, L. Knee valgus angle during landing tasks in female volleyball and basketball players. J Strength Cond Res 25(1): 262-266, 2011-Increased knee valgus angles have been associated with an increased risk of a variety of knee injuries. It has yet to be established if knee valgus angles during jump landing tasks differ between jumping sports with relatively higher and lower knee injury rates-namely, basketball and volleyball. Any difference in knee angles on landing may be related to sport-specific differences, which may in turn relate to the different injury risk rates. Fifteen elite female basketball and volleyball players had their knee valgus angles assessed during 2 landing tasks: 1 bilateral (drop jump landing) and 1 unilateral (step landing task). During the drop jump task knee valgus angle was significantly greater in the basketball group (p = 0.017) in the right knee, but there was no significant difference in performance between sports in the left knee (p = 0.67). During the step landing task volleyball players had significantly greater knee valgus angles than basketball players for both the left (p = 0.018) and right (p = 0.025) knees. The basketball group showed superior control of knee valgus during the unilateral task, which may be related to sport-specific skills. The basketball players showed significant asymmetry in knee valgus angle during bilateral drop jump landings; this finding reflects those of previous studies and may be related to the relative increased knee injury risk reported for this population group.