Spinal mobility and trunk muscle strength in elite hockey players

Elbow varus torque and ball velocity associations in high school and professional pitchers with increased sagittal-plane trunk tilt

BACKGROUND

Increased sagittal-plane trunk tilt is thought to increase drive in the anterior direction toward home plate, transferring energy from the trunk to the distal upper extremity, ultimately generating greater ball velocity. Increased sagittal trunk tilt has also been implicated in the risk of upper-extremity joint loading in baseball pitchers by way of elbow varus torque (EVT), a metric previously associated with elbow injury in professional pitchers. The purposes of this study were (1) to compare sagittal trunk tilt positioning between high school and professional pitchers throughout the pitch and (2) to identify the potential associations between sagittal-plane trunk tilt, ball velocity, and EVT for both cohorts.

METHODS

Professional and high school pitchers were instructed to throw fastballs while being evaluated with 3-dimensional motion capture (480 Hz). Sagittal trunk tilt motion throughout the pitching motion was compared between cohorts from maximum knee height to maximum shoulder internal rotation. To assess the effects of sagittal-plane trunk tilt on ball velocity and EVT, linear mixed-effect models were created.

RESULTS

Professional pitchers (n = 100, 882 pitches) achieved greater sagittal trunk tilt than high school pitchers (n = 57, 519 pitches) during early portions of the pitching motion, including maximum positive sagittal trunk tilt (46.6° ± 8.3° vs. 43.6° ± 10.2°, P = .042). Professional pitchers also had greater sagittal trunk tilt excursion throughout the pitch motion (68.0° ± 11.4° vs. 62.5° ± 11.0°, P = .004). For every 10° increase in sagittal trunk tilt at ball release for professional pitchers, ball velocity increased by 0.36 m/s (B = 0.036 and β = 0.194, P < .001) or 0.9% average ball velocity whereas EVT increased by 0.14% body weight × body height (B = 0.014 and β = 0.159, P < .001) or 2.9% average normalized EVT. For every 10° increase in sagittal trunk tilt at ball release for high school pitchers, ball velocity increased by 0.34 m/s (B = 0.097 and β = 0.025, P = .025) or 1.1% average ball velocity whereas EVT increased by 0.07% body weight × body height (B = 0.007 and β = 0.086, P = .016) or 1.7% average normalized EVT.

CONCLUSION

Increased positive sagittal-plane trunk tilt was significantly associated with greater ball velocity and increased EVT for both professional and high school pitchers. Peak EVT estimates were consistently more pronounced than ball velocity benefits for both populations, suggesting that no specific time point may provide a ball velocity benefit while concomitantly minimizing EVT. Both professional and high school pitchers should consider this trade-off, which may influence injury risk, when engaging in higher degrees of positive sagittal-plane trunk tilt.

Measurable Thoracic Motion Remains at 1 Year Following Anterior Vertebral Body Tethering, with Sagittal Motion Greater Than Coronal Motion

BACKGROUND

Anterior vertebral body tethering is an alternative to fusion surgery for the treatment of adolescent idiopathic scoliosis (AIS) that is purported to preserve spinal motion. There is limited information regarding the measurable motion that is maintained over the instrumented levels following thoracic anterior vertebral body tethering surgery in humans. The purpose of the present study was to assess radiographic spinal motion 1 year after anterior vertebral body tethering.

METHODS

As part of a prospective U.S. Food and Drug Administration investigational device exemption study, 32 patients were treated with thoracic anterior vertebral body tethering. At 1 year postoperatively, patients were evaluated with standing flexion-extension and side-bending radiographs in a microdose biplanar slot scanning imaging system. The angle subtended by the screws at the upper instrumented vertebra (UIV) and lower instrumented vertebra (LIV) was measured on left and right-bending radiographs to evaluate the coronal arc of motion and was compared with preoperative values over the same levels. At 1 year postoperatively, the sagittal Cobb angle was measured over the instrumented levels on flexion and extension radiographs.

RESULTS

Side-bending radiographs revealed that the mean angle subtended by the screws changed from 15° ± 8° on left-bending radiographs to 8° ± 6° on right-bending radiographs. The mean coronal arc of motion on bending was 7° ± 6°, with 20 (62.5%) of 32 patients having a coronal arc of motion of >5°. The mean preoperative coronal arc of motion over the instrumented segments was 30° ± 9°. On flexion-extension lateral radiographs made at 1 year postoperatively, the mean kyphotic angle over the instrumented segments was 33° ± 13° in flexion and 11° ± 14° in extension, for a mean postoperative arc of motion of 21° ± 12° between flexion and extension radiographs.

CONCLUSIONS

At 1 year following thoracic anterior vertebral body tethering for the treatment of AIS, the thoracic spine showed a measurable range of coronal and sagittal plane motion over the instrumented levels without evidence of complete autofusion. Motion in the coronal plane decreased by 77% following anterior vertebral body tethering. These findings provide proof of concept that sagittal spinal motion is preserved after thoracic anterior vertebral body tethering, although the functional importance remains to be determined.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Between-side differences in trunk rotational power in athletes trained in asymmetric sports

BACKGROUND

The asymmetric loading of trunk muscles in sports like golf or tennis may cause side-to-side imbalances in rotational muscle strength and endurance. Such imbalances may be compounded by the presence of low back pain (LBP) and related injuries. However, trunk rotational power is a better predictor of athlete performance, and therefore its ability to reveal these asymmetries/dysbalances should be investigated.

OBJECTIVE

This study compares peak and mean values of power during trunk rotations on the dominant and non-dominant side in golfers, ice-hockey players, tennis players, and an age-matched control group of fit individuals.

METHODS

Groups of 17 golfers, 17 ice-hockey players, 21 tennis players, and 39 fit individuals performed standing trunk rotations to each side with a bar weight of 5.5, 10.5, 15.5, and 20 kg placed on the shoulders. Peak power and mean power in the acceleration phase of trunk rotations were measured using the FiTRO Torso Premium system.

RESULTS

Peak power and mean power in the acceleration phase of trunk rotations were significantly higher on the dominant (D) than non-dominant (ND) side at weights of 5.5 kg (14 and 14%), 10.5 kg (17 and 14%), 15.5 kg (16 and 15%), and 20 kg (16 and 16%) in ice-hockey players, at 5.5 kg (14 and 13%), 10.5 kg (17 and 14%), and 15.5 kg (15% - only peak power) in tennis players, and at 5.5 kg (17 and 18%) and 10.5 kg (19 and 17%) in golfers. However, their values did not differ significantly at these weights (< 10%) in the age-matched control group. The D/ND ratio was the highest in ice-hockey players (1.18, 1.19), followed by golfers (1.16, 1.17) and finally tennis players (1.12, 1.16).

CONCLUSION

Taking into account significantly higher trunk rotational power on the dominant than the non-dominant side in golfers, tennis players and ice-hockey players at lower and/or higher weights and no significant side-to-side differences in a control group of fit individuals, this parameter may be considered specific to their asymmetric loading during trunk rotations. However, whether these asymmetries/dysbalances expressed by the D/ND ratio could also identify the likelihood of LBP, needs to be proven.

Prevalence of Back Pain in Sports: A Systematic Review of the Literature

Background

Back pain is a frequent health problem in the general population. The epidemiology of back pain in the general population is well researched, but detailed data on the prevalence and risk factors of back pain in athletes are rare.

Objective

The primary objective was to review articles about back pain in athletes to provide an overview of its prevalence in different sports and compare its prevalence among various types of sports and the general population.

Data Sources

A comprehensive search of articles published through May 2015 was conducted. Two independent reviewers searched six databases from inception (PubMed^®, Embase, MEDLINE^®, Cochrane Library, PsycINFO and PSYNDEX), using specifically developed search strategies, for relevant epidemiological research on back pain in 14- to 40-year-old athletes of Olympic disciplines. The reviewers independently evaluated the methodological quality of reviewed articles meeting the inclusion criteria to identify potential sources of bias. Relevant data were extracted from each study.

Results

Forty-three articles were judged to meet the inclusion criteria and were included in the assessment of methodological quality. Of these, 25 were assessed to be of high quality. Lifetime prevalence and point prevalence were the most commonly researched episodes and the lower back was the most common localization of pain. In the high-quality studies, lifetime prevalence of low back pain in athletes was 1–94%, (highest prevalence in rowing and cross-country skiing), and point prevalence of low back pain was 18–65% (lowest prevalence in basketball and highest prevalence in rowing).

Conclusion

The methodological heterogeneity of the included studies showed a wide range of prevalence rates and did not enable a detailed comparison of data among different sports, within one discipline, or versus the general population. Based on the results of this review, however, it seems obvious that back pain requires further study in some sports.

Electronic supplementary material

The online version of this article (doi:10.1007/s40279-016-0645-3) contains supplementary material, which is available to authorized users.

Does field hockey increase morphofunctional asymmetry? A pilot study

Common practice in field hockey requires athletes to adopt a semi-crouched posture, so players have a greater risk of musculoskeletal disorders than non-athletes. The aim of the present study was to assess how field hockey determines asymmetry in morphological and functional characteristics of the body by comparing athletes to control participants. The sample consisted of 15 male field hockey players from the Polish Youth National Team and 14 male university students. Antimeric differences in the chosen variables between body sub-regions were assessed. All morphological characteristics (bone mineral density, fat mass, and lean mass) were estimated using a dual energy X-ray absorptiometry. Additionally, the range of motion in transverse and frontal planes of the cervical, thoracic and lumbar spine was measured by using an electrogoniometric system. The results showed that the values of all morphological characteristics were higher in the left body segments, both in athletes and controls. However, the differences between sides were much more pronounced in the field hockey players. With regard to functional traits, higher values were obtained for the right body side in athletes but for the left side of the body among the controls. The difference between right and left side bending increased from the cervical spine (2.7%) through thoracic spine (7.8%) to lumbar spine (16.5%) in athletes. Rotational asymmetry in the thoracic spine was the largest in both groups. These findings indicate that it is important to monitor all athletes to prevent injury and health problems connected with strong morphological asymmetry.

Back pain in elite sports: A cross-sectional study on 1114 athletes

OBJECTIVES

To establish the prevalence of back pain in German elite athletes; examine the influence of age, sex, sports discipline and training volume; and compare elite athletes with a physically active control group.

METHODS

A standardized and validated online back pain questionnaire was sent by the German Olympic Sports Confederation to approximately 4,000 German national and international elite athletes, and a control group of 253 physically active but non-elite sports students.

RESULTS

We received responses from 1,114 elite athletes (46.5% male and 53.1% female, mean age 20.9 years ± 4.8 years, mean height 176.5 ± 11.5 cm, mean weight 71.0 ± 10.3 kg) and 166 physically active sports students (74.7% male and 24.1 female, mean age 21.2 ± 2.0 years, mean height 180.0 ± 8.0 cm, mean weight 74.0 ± 14.5 kg). In elite athletes, the lifetime prevalence of back pain was 88.5%, the 12-month prevalence was 81.1%, the 3-month prevalence was 68.3% and the point prevalence was 49.0%, compared with 80.7%, 69.9%, 59.0% and 42.8%, respectively in the control group. The lifetime, 12-month and 3-month prevalences in elite athletes were significantly higher than in the control group. Regarding the individual sports disciplines, the prevalence of back pain was significantly higher in elite rowers, dancers, fencers, gymnasts, track and field athletes, figure skaters and marksmen, and those who play underwater rugby, water polo, basketball, hockey and ice hockey compared with the control group. The prevalence of back pain was significantly lower in elite triathletes.

CONCLUSIONS

Back pain is a common complaint in German elite athletes. Low back pain seems to be a problem in both elite athletes and physically active controls. A high training volume in elite athletes and a low training volume in physically active individuals might increase prevalence rates. Our findings indicate the necessity for specific prevention programs, especially in high-risk sports. Further research should investigate the optimal dose-effect relationship of sporting activity for the general population to prevent back pain.

Isokinetic trunk strength and lumbosacral range of motion in elite female field hockey players reporting low back pain

This study was funded, in part, by a Small Faculties Grant from the University of Alberta. Physical therapists have reported an increased incidence of low back pain (LBP) in female field hockey (FH) players, commonly accompanied by decreased trunk range of motion (ROM) and strength. The purpose of this study was to compare lumbosacral sagittal ROM and isokinetic trunk strength in three groups of women: 1) FH athletes with a history of chronic LBP, 2) pain-free FH athletes, and 3) an age-matched, healthy nonathletic control group. Photographs (35 mm) of subjects wearing spinal motion markers were used to determine the limits of lumbosacral saggital ROM in standing. Eccentric and concentric isokinetic trunk flexion and extension torques were measured in sitting through 60 degrees of trunk movement using a Kin-Com dynamometer set at 60 degrees /sec. The ANOVA showed that the pain group had 12 degrees and 18 degrees less extension (p < .01), as well as 18 degrees and 24 degrees less total ROM (p < .001) than the pain-free and control groups, respectively. Only peak (p < .001) and average (p < .03) eccentric extension torques were weaker in the pain group than in the nonathletic control group. These results suggest that physical therapists should perform preseason screening of trunk strength and lumbosacral ROM. In-season trunk extension stretching and strengthening is needed in the training regimes of these athletes. J Orthop Sports Phys Ther 1992;16(3):129-135.

An isokinetic evaluation of trunk strength in elite female field hockey players

A Kin-Corn dynamometer was used to evaluate trunk extensor and flexor strength in 11 elite female field hockey players. Average torques during maximal concentric and eccentric muscle actions through a range of movement from 25° of extension to 30° of flexion were measured at angular velocities of 30°.s(-1) and 60°.s(-1). Strength curve shape, average torque values and derived eccentric/concentric and trunk extensor/flexor ratios were analysed. The strength curves displayed greatest torques in the lengthened position for both muscle groups. Statistical analysis revealed no significant difference in strength between first and second test occasions (p=0.9920). Muscle action (eccentric versus concentric) and group (extensors versus flexors) were significant main effects (p <0.0001). There was no significant difference between torques at 30°.s(-1) and 60°.s(-1). The trunk extensor/flexor ratio approximated 1.75 for eccentric muscle action and 1.82 for concentric muscle actions. Gravity correction did not affect strength data but did affect strength curve shape. The results can be utilised to design individual prophylactic exercise programs for back pain.