The effect of motor control training on abdominal muscle contraction during simulated weight bearing in elite cricketers

Altered lower extremity muscle activity patterns due to Iliopsoas tightness during single-leg landing

This study aims to investigate the impact of iliopsoas (IL) tightness on lower extremity muscle activity during single-leg landing, focusing on how IL tightness influences joint protection through feed-forward and feed-back pathways that address known impaired neuromuscular mechanisms and provide a set of variables with which to assess and design the ongoing change from both prevention and management. A cross-sectional study of 28 male soccer players (ages 11-14 yrs) divided into IL tightness (n = 14) and normal hip flexor length (n = 14) groups assessed hip extension range using the modified Thomas test. Electromyography recorded muscle activity (gluteus maximus [GM], adductor magnus [AM], biceps femoris [BF], rectus femoris [RF], soleus [SOL], and multifidus [MF]) during single-leg landing, with RMS values computed over 50 ms epochs, collected 300 ms before and after ground contact, and normalized to maximal voluntary isometric contractions (MVIC). Statistical analysis using Kolmogorov-Smirnov and homoscedasticity tests confirmed normal distribution and homogeneity. Independent-sample t-tests compared muscle activity between groups and Cohen's d effect size was calculated. All analyses were done using SPSS with significance set at p ≤ 0.05. Specifically, participants with IL tightness had reduced activation of the RF (p = 0.01) and SOL (p = 0.003) during feed-forward action and increased activation of the MF compared to the normal group (p = 0.008). During feed-back action, those with IL tightness demonstrated increased activation of the GM (p = 0.01), BF (p = 0.03), AM (p = 0.01) and MF (p = 0.017), whereas showing reduced activation of the RF (p = 0.02) and SOL (p = 0.01). Subtle differences were observed in how adolescent soccer players with iliopsoas tightness utilize their lower extremity muscles through kinetic chains during single-leg landing compared to healthy controls. These findings enhance our understanding of the complex functional consequences of iliopsoas tightness on motor control changes and underscore the importance of monitoring the effectiveness of interventions aimed at joint protection in this specific demographic.

Exploring the relationship between trunk muscles and lower limb injuries in Australian badminton players

Due to its dynamic nature, lower limb injuries are common in badminton. Overuse injuries of the knee, including tendon related conditions, are the most common. During jumping and landing, force transference and dissipation through the trunk is required, with the trunk muscles playing a vital role. However, the relationship between knee pain and the ability to voluntarily contract the trunk muscles has not yet been explored in badminton players. A cross-sectional study of Australian badminton players was therefore conducted. Players performed a single leg decline squat to identify those with knee pain. Ultrasound imaging was used to image and measure the size of the multifidus and quadratus lumborum, and the ability to contract the abdominal and multifidus muscles. Voluntary contraction of the trunk muscles was conducted with the subjects lying down. Independent samples T-Tests were performed to test for between group differences. Badminton players with knee pain had larger quadratus lumborum muscles and demonstrated a greater change in muscle thickness from the rested to contracted state. While we cannot comment on causation or direction, over co-contraction of trunk muscles has been shown in other studies to be associated with increased ground reaction forces on landing. Motor control training has been successfully used in other conditions to modify trunk muscle recruitment patterns and may therefore potentially represent a useful approach for badminton players.

The effects of exposure to microgravity and reconditioning of the lumbar multifidus and anterolateral abdominal muscles: implications for people with LBP

BACKGROUND CONTEXT

One of the primary changes in the neuromuscular system in response to microgravity is skeletal muscle atrophy, which occurs especially in muscles that maintain posture while being upright on Earth. Reduced size of paraspinal and abdominal muscles has been documented after spaceflight. Exercises are undertaken on the International Space Station (ISS) during and following space flight to remediate these effects. Understanding the adaptations which occur in trunk muscles in response to microgravity could inform the development of specific countermeasures, which may have applications for people with conditions on Earth such as low back pain (LBP).

PURPOSE

The aim of this study was to examine the changes in muscle size and function of the lumbar multifidus (MF) and anterolateral abdominal muscles (1) in response to exposure to 6 months of microgravity on the ISS and (2) in response to a 15-day reconditioning program on Earth.

DESIGN

Prospective longitudinal series.

PATIENT SAMPLE

Data were collected from five astronauts who undertook seven long-duration missions on the ISS.

OUTCOME MEASURES

For the MF muscle, measures included cross-sectional area (CSA) and linear measures to assess voluntary isometric contractions at vertebral levels L2 to L5. For the abdominal muscles, the thickness of the transversus abdominis (TrA), obliquus internus abdominis (IO) and obliquus externus abdominis (EO) muscles at rest and on contraction were measured.

METHODS

Ultrasound imaging of trunk muscles was conducted at four timepoints (preflight, postflight, mid-reconditioning, and post reconditioning). Data were analyzed using multilevel linear models to estimate the change in muscle parameters of interest across three time periods.

RESULTS

Beta-coefficients (estimates of the expected change in the measure across the specified time period, adjusted for the baseline measurement) indicated that the CSA of the MF muscles decreased significantly at all lumbar vertebral levels (except L2) in response to exposure to microgravity (L3=12.6%; L4=6.1%, L5=10.3%; p<.001), and CSAs at L3-L5 vertebral levels increased in the reconditioning period (p<.001). The thickness of the TrA decreased by 34.1% (p<.017), IO decreased by 15.4% (p=.04), and the combination of anterolateral abdominal muscles decreased by 16.2% (p<.001) between pre- and postflight assessment and increased (TrA<0.008; combined p=.035) during the postreconditioning period. Results showed decreased contraction of the MF muscles at the L2 (from 12.8% to 3.4%; p=.007) and L3 (from 12.2% to 5%; p=.032) vertebral levels following exposure to microgravity which increased (L2, p=.046) after the postreconditioning period. Comparison with preflight measures indicated that there were no residual changes in muscle size and function after the postreconditioning period, apart from CSA of MF at L2, which remained 15.3% larger than preflight values (p<.001).

CONCLUSIONS

In-flight exercise countermeasures mitigated, but did not completely prevent, changes in the size and function of the lumbar MF and anterolateral abdominal muscles. Many of the observed changes in size and control of the MF and abdominal muscles that occurred in response to prolonged exposure to microgravity paralleled those seen in people with LBP or exposed to prolonged bed rest on Earth. Daily individualized postflight reconditioning, which included both motor control training and weight-bearing exercises with an emphasis on retraining strength and endurance to re-establish normal postural alignment with respect to gravity, restored the decreased size and control of the MF (at the L3-L5 vertebral levels) and anterolateral abdominal muscles. Drawing parallels between changes which occur to the neuromuscular system in microgravity and which exercises best recover muscle size and function could help health professionals tailor improved interventions for terrestrial populations. Results suggested that the principles underpinning the exercises developed for astronauts following prolonged exposure to microgravity (emphasizing strength and endurance training to re-establish normal postural alignment and distribution of load with respect to gravity) can also be applied for people with chronic LBP, as the MF and anterolateral abdominal muscles were affected in similar ways in both populations. The results may also inform the development of new astronaut countermeasures targeting the MF and abdominal muscles.

Convergence and Divergence of Exercise-Based Approaches That Incorporate Motor Control for the Management of Low Back Pain

Many approaches for low back pain (LBP) management focus on modifying motor control, which refers to motor, sensory, and central processes for control of posture and movement. A common assumption across approaches is that the way an individual loads the spine by typical postures, movements, and muscle activation strategies contributes to LBP symptom onset, persistence, and recovery. However, there are also divergent features from one approach to another. This commentary presents key principles of 4 clinical physical therapy approaches, including how each incorporates motor control in LBP management, the convergence and divergence of these approaches, and how they interface with medical LBP management. The approaches considered are movement system impairment syndromes of the lumbar spine, Mechanical Diagnosis and Therapy, motor control training, and the integrated systems model. These were selected to represent the diversity of applications, including approaches using motor control as a central or an adjunct feature, and approaches that are evidence based or evidence informed. This identification of areas of convergence and divergence of approaches is designed to clarify the key aspects of each approach and thereby serve as a guide for the clinician and to provide a platform for considering a hybrid approach tailored to the individual patient. J Orthop Sports Phys Ther 2019;49(6):437-452. Epub 15 May 2019. doi:10.2519/jospt.2019.8451.

Ultrasonography features of abdominal perimuscular connective tissue in elite and amateur basketball players: an observational study

SUMMARY The purpose of this study was to assess and compare with rehabilitative ultrasound imaging (RUSI) the perimuscular connective tissue (PMCT) and interrecti distance (IRD) between elite and amateur basketball players. A sample of 22 healthy basketball players was included and divided into two groups: elite basketball players from Spanish 1st division (n = 11) and amateur basketball players from an entertainment Spanish division (n = 11). Ultrasound images of the external oblique (EO), internal oblique (IO), transversus abdominis (TrAb), rectus anterior (RA) and IRD PMCT were measured and analysed by the ImageJ software. Measurements of abdominal wall muscles PMCT present statistically differences (P < .05) for an increase of perimuscular connective tissue of external oblique (PMCTEO), perimuscular connective tissue of transversus abdominis (PMCTTA) of the left side and an increase of PMCTEO on the right side in favor of the elite group. Rather, the study showed statistically differences (P < .05) for a decrease of perimuscular connective tissue between the internal oblique and transversus abdominis (PMCTIO-TA), and a decrease in PMCT total summation of the left side with elite group in respect to amateur group. This study reported an increase of left PMCTEO, left PMCTTAA, right PMCTEO as well as a decrease of left PMCTIO-TA and in PMCT total summation on the left side.

Asymmetrical abdominal muscle morphometry is present in injury free adolescent cricket pace bowlers: A prospective observational study

OBJECTIVES

This study aimed to determine if abdominal muscle thickness, activation and symmetry are associated with prospective in-season injury among adolescent cricket pace bowlers.

DESIGN

A quantitative, prospective, observational study design was used.

SETTING

Data was collected at an indoor venue at a secondary school.

PARTICIPANTS

28 injury-free, male, adolescent pace bowlers between the ages of 13 and 18 participated.

MAIN OUTCOME MEASURES

Muscle thickness of the transversus abdominis (TA), internal oblique (IO) and external oblique (EO) muscles were measured at rest and during an abdominal drawing-in maneuver (ADIM) i.e. activation, using ultrasound imaging. Incidence of injury was monitored monthly during the cricket season.

RESULTS

Thickness of the non-dominant IO at rest was greater than the dominant side for pace bowlers who remained injury free during the cricket season (p = 0.01, effect size (ES) = 0.65). This was, however not the case for bowlers who sustained injuries (p = 0.47; ES = 0.24). TA percentage change during ADIM (activation) on the dominant side was less in bowlers who sustained non-contact injuries compared to those who remained injury free (p = 0.03; ES = 1.17).

CONCLUSIONS

Asymmetry in IO thickness may play a protective role against injury, whilst poor TA activation on the dominant side may pose a risk to injury.