The association between student body mass index and tests of flexibility assessed by the FITNESSGRAM®: New York City public school students, 2017–18

FITNESSGRAM® is the most widely used criterion-referenced tool to assess/report on student health-related fitness across the US. Potential weight-related biases with the two most common tests of musculoskeletal fitness–the trunk extension and Back-Saver Sit-and-Reach (sit-and-reach)—have been hypothesized, though have not been studied. To determine the association between musculoskeletal fitness test performance and weight status, we use data from 571,133 New York City public school 4th-12th grade students (85% non-White; 75% qualified for free or reduced-price meals) with valid/complete 2017–18 FITNESSGRAM® data. Adjusted logistic mixed effects models with a random effect for school examined the association between weight status and whether a student was in the Healthy Fitness Zone (HFZ; met sex- and age-specific criterion-referenced standards) for the trunk extension and sit-and-reach. Compared to students with normal weight, the odds of being in the HFZ for trunk extension were lower for students with underweight (OR = 0.77; 95% CI: 0.741, 0.795) and higher for students with overweight (OR = 1.10; 95% CI: 1.081, 1.122) and obesity (OR = 1.11; 95% CI: 1.090, 1.13). The odds of being in the HFZ for sit-and-reach were lower for students with underweight OR = 0.85; 95% CI: 0.826, 0.878), overweight (OR = 0.83; 95% CI: 0.819, 0.844) and obesity (OR = 0.65; 95% CI: 0.641, 0.661). Students with overweight and obesity perform better on the trunk extension, yet worse on the sit-and-reach, compared to students with normal weight. Teachers, administrators, and researchers should be aware of the relationship of BMI with student performance in these assessments.

Is Dynamic Spino-Pelvic Alignment During Gait Associated with Quality of Life in Patients with Degenerative Lumbar Spinal Canal Stenosis?

This study aims to investigate the relationship between dynamic alignment of the spine and pelvis during gait and quality of life (QOL) in lumbar spinal canal stenosis (LSS) patients. We evaluated QOL using the Oswestry Disability Index (ODI), trunk and hip muscle strength as physical function, static spinal alignment, and dynamic spinal/pelvic alignment during gait. The relationship between the ODI score and physical function or static and dynamic alignment were examined. A total of 30 preoperative patients with LSS were participated in this study. ODI score significantly correlated with trunk extension strength (r = -0.559, p = 0.002), hip extension strength (r = -0.473, p = 0.011), maximum flexion angle of spine during gait (r = -0.551, p = 0.002) and maximum anterior tilt angle of pelvis (r = 0.528, p = 0.004). Multiple regression analysis showed that trunk extension strength (standardized β; - 0.35), maximum spinal flexion angle (standardized β; - 0.51) and hip extension strength (standardized β; - 0.40) significantly affected the ODI score, with adjusted coefficient of determination of 0.62. The results of this study showed that the LSS patients with weak hip or trunk extensor muscles, a greater angle of pelvic tilt or a less spinal flexion during gait had a lower QOL.

Kinematic analysis of movement impaired by generalization of fear of movement-related pain in workers with low back pain

Purpose To identify impaired trunk movement during work-related activity in individuals with low back pain (LBP) and investigate whether abnormalities were caused by generalized fear of movement-related pain. Methods This cross-sectional study was conducted at a hospital in Japan. We recruited 35 participants with LBP (LBP group; 26 males, 9 females) and 20 healthy controls (HC group) via posters at our hospital. The task required lifting an object. We used a 3D motion capture system to calculate the peak angular velocity of trunk flexion and extension during a lifting task. Pain-related factors for the LBP group were assessed using the visual analogue scale (VAS) for pain intensity over the past 4 weeks and during the task, the Tampa Scale for Kinesiophobia (TSK), the Pain Catastrophizing Scale (PCS), and the Pain Anxiety Symptoms Scale-20 (PASS-20). We compared kinematic variables between groups with a generalized linear mixed model and investigated the relationship between kinematic variables, VAS scores, and psychological factors by performing a mediation analysis. Results The peak angular velocity of trunk extension showed significant main effects on the group factors (LBP group vs. HC group) and their interactions; the value of the kinematic variable was lower at Trial 1 in the LBP group. No LBP participant reported pain during the experiment. The mediation analysis revealed that the relationship between the VAS score for pain intensity over the past 4 weeks and the peak angular velocity of trunk extension in the first trial was completely mediated by the TSK (complete mediation model, 95% bootstrapped CI: 0.07–0.56). Conclusion Individuals with LBP had reduced trunk extension during a lifting task. Generalized fear of movement-related pain may contribute to such impaired trunk movement. Our findings suggest that intervention to ameliorate fear of movement may be needed to improve LBP-associated disability.

Differences in myoelectric activity of the lumbar muscles between recurrent and chronic low back pain: a cross-sectional study

Background Altered lower back muscle activity is proposed as a contributing factor to the reoccurrence and chronicity of low back pain (LBP). This study compared lumbar muscle activity during trunk extension in patients with continuous chronic LBP (CLBP), non-continuous CLBP, recurrent LBP (RLBP) and healthy subjects. Methods In 75 subjects (16 continuous CLBP, 15 non-continuous CLBP, 23 RLBP, 21 healthy controls), surface electromyographic (EMG) activity of the lumbar erector spinae (ES), multifidus (MF), latissimus dorsi (LD) and gluteus maximus (GM) was recorded during the concentric, holding and eccentric phase of a modified Biering Sorenson exercise. Results Continuous CLBP patients showed higher EMG activity in the ES and MF muscles compared to healthy controls in the concentric (p = 0.011; p = 0.009 respectively) and the holding phase (p = 0.015; p = 0.013). Higher EMG activity was observed in continuous CLBP compared to RLBP in the ES and MF muscles in the holding phase (p = 0.035; p = 0.037), and in the MF in the concentric phase (p = 0.046), but not in the ES (p = 0.062). No differences in muscle activity were established in either the concentric, holding, and eccentric phase for the LD and GM muscles. No differences were found between non-continuous CLBP and the other groups. Conclusions An enhanced muscle activity of the lumbar muscles during the concentric and holding phase was observed during trunk extension in patients with continuous CLBP compared to patients with RLBP and healthy subjects. No differences between groups are present in the GM and LD muscles during concentric and holding phases and for any muscle in the eccentric phase.

Effects of Intended Scapular Posterior Tilt Motion on Trapezius Muscle Electromyography Activity

The intended scapular motion is a strategy to strengthen the lower trapezius (LT). However, few studies have explored the effects of the intended scapular posterior tilt motion on selective LT activation. Thus, the present study investigated the effect of the intended scapular posterior tilt on the electromyography (EMG) activity of trapezius muscles during prone shoulder horizontal abduction (PSHA). Eighteen asymptomatic men performed three types of PSHA: (1) preferred PSHA, (2) PSHA with the intended scapular posterior tilt, and (3) PSHA with the intended scapular posterior tilt and trunk extension. EMG activity of the upper trapezius (UT), middle trapezius (MT), and LT were measured during PSHAs. Scapular posterior tilt angle, with and without the intended scapular posterior tilt, were measured using inclinometer. The results indicated that LT muscle activity increased when scapular posterior tilt was applied with and without trunk extension (14–16%), compared to the preferred condition, during PSHA (p < 0.05). However, the addition of trunk extension to PSHA with the intended scapular posterior tilt increased the UT muscle activity (28%) and the UT/LT (29%) and UT/MT (31%) ratios (p < 0.05). The scapular posterior tilt angle was higher (15%) when applying the intended scapular posterior tilt (p = 0.020). These findings suggest that the intended scapular posterior tilt may be a useful strategy for selective LT muscle activation.

Efficacy of Whole-Body Electromyostimulation (WB-EMS) on Body Composition and Muscle Strength in Non-athletic Adults. A Systematic Review and Meta-Analysis

This systematic review and meta-analysis set out to determine the efficacy on whole-body electromyostimulation (WB-EMS) on body composition and strength parameters in non-athletic cohorts. A systematic review of the literature according to the PRISMA statement included (a) controlled trials, (b) WB-EMS trials with at least one exercise and one control group, (c) WB-EMS as primary physical intervention, (d) WB-EMS with at least six electrodes covering most muscle groups, (e) non-athletic cohorts. We searched eight electronic databases up to June 30, 2020, without language restrictions. Standardized mean differences (SMD) for muscle mass parameters, total body fat mass, maximum leg extension, and trunk extension strength were defined as outcome measures. In summary, 16 studies with 19 individual WB-EMS groups representing 897 participants were included. Studies vary considerably with respect to age, BMI, and physical conditions. Impulse protocols of the studies were roughly comparable, but training frequency (1–5 sessions/week) and intervention length (6–54 weeks) differed between the studies. SMD average was 1.23 (95%-CI: 0.71–1.76) for muscle mass, 0.98 (0.74–1.22) for maximum leg, and 1.08 (0.78–1.39) for maximum trunk extension strength changes (all p &lt; 0.001). SMD for body fat changes (−0.40, [−0.98 to 0.17]), however, did not reach significance. I2 and Q-statistics revealed substantial heterogeneity of muscle and fat mass changes between the trials. However, rank and regression tests did not indicate positive evidence for small-study bias and funnel plot asymmetries. This work provided further evidence for significant, large-sized effects of WB-EMS on muscle mass and strength parameters, but not on body fat mass.Clinical Trial Registration:ClinicalTrials.gov, PROSPERO; ID: CRD42020183059.

Kinematic Differences Exist Between the Fastball, Changeup, Curveball, and Dropball Pitch Types in Collegiate Softball Pitchers

Background: A majority of softball literature focuses on the mechanics associated with pain and injury within a single pitch type per study; however, the generalizability of these findings is unknown since a kinematic comparison has yet to be performed between pitch types. Understanding kinematic differences between pitch types can be used to identify risk factors for injury, improve safety guidelines, and improve performance by linking specific mechanics with desired pitch outcomes. Hypothesis/Purpose: The purpose of this study was to compare kinematics between the fastball, changeup, curveball, and dropball pitch types in collegiate softball pitchers. It was hypothesized that there would be significant kinematic differences between pitch types. Study Design: Descriptive laboratory study. Methods: A total of 28 female collegiate softball pitchers pitched 3 trials of each pitch type to a catcher at regulation distance. Pitch speed, stride length, trunk extension, trunk rotation, trunk lateral flexion, elbow flexion, and center of mass for each trial were calculated using an electromagnetic motion capture system and were averaged for analysis. A 1-way analysis of variance (ANOVA) was used to investigate pitch speed differences between the 4 pitch types. A 4 (pitch type) × 5 (event) within-athlete multivariate ANOVA was also used to determine kinematic differences. Results: The results revealed a significant difference in pitch speed between pitch types; a pitch type main effect for trunk extension, trunk rotation, trunk lateral flexion, and center of mass; and an event main effect for all variables except stride length. The results also revealed a pitch type by event interaction for trunk flexion, trunk lateral flexion, and center of mass. Specifically, the dropball type had less trunk extension than the fastball at all pitching events. Similarly, the curveball type had a more posteriorly shifted center of mass than the dropball at the last 3 pitching events of foot contact, ball release and follow-through. Conclusion: Significant kinematic differences exist between pitch types, but these differences may be necessary to execute desired pitch outcomes. Clinical Relevance: This is the first study to analyze kinematic differences between pitch types in softball pitchers. Understanding the effects of different pitch types on kinematic parameters may enhance injury prevention and performance strategies for softball pitchers.

Muscular Fitness Improves during the First Year of Academy Studies among Fighter Pilot Cadets

Background: An adequate level of muscular fitness is related to occupational performance in military personnel, including pilots flying high performance aircraft. The aim of this study was to describe the baseline level and the change in muscular fitness between the first and the second years of the Air Force Academy among fighter pilot cadets. Methods: The muscular strength and endurance test results of 182 male fighter pilot cadets were analyzed during their first year in the Air Force Academy and one year after. Maximal isometric strength tests included trunk flexion, trunk extension and bilateral leg extension tests, whereas muscle endurance was measured with modified a sit-up test and seated alternative dumbbell press. Results: The maximal isometric bilateral strength of the leg extensor muscles increased from 220 ± 42 to 232 ± 42 kg. The maximal isometric trunk extension strength increased from 117 ± 21 to 120 ± 19 kg and trunk flexion from 82 ± 16 to 86 ± 17 kg. Muscle endurance increased from 68 ± 13 to 75 ± 15 repetitions/min in seated dumbbell press and from 47 ± 12 to 51 ± 13 repetitions/min in sit-up test. Conclusions: Both maximal strength and muscular endurance improved among fighter pilot cadets, which indicates that occupational performance is well maintained or improved from the perspective of physical fitness during the early phase of academy studies. Education in the Air Force Academy, including physical education, seems beneficial in improving muscular fitness among military pilots.

A Random Forest Machine Learning Framework to Reduce Running Injuries in Young Triathletes

Background: The running segment of a triathlon produces 70% of the lower limb injuries. Previous research has shown a clear association between kinematic patterns and specific injuries during running. Methods: After completing a seven-month gait retraining program, a questionnaire was used to assess 19 triathletes for the incidence of injuries. They were also biomechanically analyzed at the beginning and end of the program while running at a speed of 90% of their maximum aerobic speed (MAS) using surface sensor dynamic electromyography and kinematic analysis. We used classification tree (random forest) techniques from the field of artificial intelligence to identify linear and non-linear relationships between different biomechanical patterns and injuries to identify which styles best prevent injuries. Results: Fewer injuries occurred after completing the program, with athletes showing less pelvic fall and greater activation in gluteus medius during the first phase of the float phase, with increased trunk extension, knee flexion, and decreased ankle dorsiflexion during the initial contact with the ground. Conclusions: The triathletes who had suffered the most injuries ran with increased pelvic drop and less activation in gluteus medius during the first phase of the float phase. Contralateral pelvic drop seems to be an important variable in the incidence of injuries in young triathletes.