Effect of abdominal bracing training on strength and power of trunk and lower limb muscles

Effects of abdominal hollowing and bracing on each intervertebral angle during quadruped upper and lower extremity lift: Three-dimensional motion analysis of the spine

To investigate the effects of intentionally minimizing spinal motion and abdominal muscle contractions on intervertebral angles during quadruped upper and lower extremity lift (QULEL). Fifteen healthy men performed the QULEL under four conditions: without any special instructions (basic), with the intention to minimize spinal motion (intentional), with abdominal bracing (bracing), and with abdominal hollowing (hollowing). Each intervertebral angle was calculated from the local coordinate system using the marker data obtained from a motion capture system. Shear moduli, as indicators of the activities of the right transversus abdominis (TrA), internal and external oblique, and rectus abdominis muscles, were assessed using shear wave elastography during QULEL. One-way repeated-measures analysis of variance and multiple comparisons among conditions were used to compare each shear modulus of the abdominal muscle and the changes in thoracic kyphosis (Th1-12), lumbar lordosis (L1-5), and lumbar intervertebral angles from the quadruped position to QULEL. The significance level was set at P < 0.05. Changes in lumbar lordosis and L2/L3 and L3/L4 extension angles were significantly lower under hollowing than under other conditions (effect size ηG2: lumbar lordosis, 0.068; L2/L3, 0.072; L3/L4, 0.043). The change in the L1/L2 extension angle significantly decreased in bracing and hollowing compared with the basic (ηG2 = 0.070). Only the TrA shear modulus significantly increased in bracing and hollowing compared with the basic (ηG2 = 0.146). Abdominal hollowing during the QULEL increased TrA activity and suppressed lumbar extension, except at L4/L5, and may be more effective as a rehabilitation exercise for controlling spinal motion.

Effect of adding abdominal bracing to spinal stabilization exercise on lumbar lordosis angle, extensor strength, pain, and function in patients with non-specific chronic low back pain: A prospective randomized pilot study

TRIAL DESIGN

This study investigated the effect of adding abdominal bracing to spinal stability exercise in patients with chronic low back pain (CLBP). This prospective, randomized pilot study included 67 patients and was conducted at the sports medicine center of a single hospital.

METHODS

The abdominal bracing group (ABBG) underwent spinal stability exercise with abdominal bracing (N = 33), comprising 50 minutes training twice a week for 24 weeks. The control group performed only spinal stability exercise (N = 34) for 50 minutes twice a week for 24 weeks. The ABBG received abdominal bracing training at each session and applied abdominal bracing during the spinal stability exercise. The lumbar lordosis angle (LLA) and spine extensor muscle strength were measured. Spinal flexion angles were measured every 12° from 0° to 72°. The visual analog scale score and Oswestry disability index were measured before treatment and at 12 and 24 weeks after treatment.

RESULTS

The LLA increased over time in both the groups but was not significantly different between the groups. Spine extensor strength was improved over time in both the groups, and an interactive effect was observed at a spinal flexion angle of 60° and 72°. Pain and function were also improved over time in both the groups, but the effect was stronger in the ABBG than in the control group. In patients with CLBP, spinal stability exercise changed the LLA.

CONCLUSIONS

Although adding abdominal bracing to spinal stability exercise did not affect the changes in the LLA, abdominal bracing improved the spinal extensor strength, pain, and function in patients with CLBP. Therefore, it is recommended to add abdominal bracing to spinal stability exercise to maintain the lordosis angle and to improve CLBP symptoms.

The Effect of Volitional Preemptive Abdominal Contraction on Biomechanical Measures During A Front Versus Back Loaded Barbell Squat

Background

Weightlifting is growing in popularity among recreational and competitive athletes. The barbell back squat (BackS) is commonly included in these training programs, while the barbell front squat (FrontS) is commonly performed as a component of other lifts such as the power clean or clean and jerk, it is less commonly practiced in isolation.

Hypothesis/Purpose

The purpose of this study was to examine the effects of VPAC performance on trunk muscle and LE biomechanical responses during loaded BackS versus FrontS in healthy subjects.

Study Design

Controlled Laboratory Study.

Methods

Healthy male subjects with the ability to perform a sub-maximal loaded barbell squat lift were recruited. Subjects completed informed consent, demographic/medical history questionnaires and an instructional video. Subjects practiced VPAC and received feedback. Surface electromyography (sEMG) electrodes and kinematic markers were applied. Muscles included were the internal oblique (IO), external oblique (EO), rectus abdominis, iliocostalis lumborum (ICL), superficial multifidi, rectus femoris, vastus lateralis, biceps femoris, and gluteus maximus. Maximal voluntary isometric contractions established reference sEMG values. A squat one-rep-max (1RM) was predicted by researchers using a three to five repetition maximum (3RM, 5RM) load protocol. Subjects performed BackS trials at 75% 1RM while FrontS trials were performed at 75% BackS weight, both with and without VPAC. Subjects performed three repetitions of each condition with feet positioned on two adjacent force plates. Significant interactions and main effects were tested using a 2(VPAC strategy) x 2(squat variation) and 2(VPAC strategy) x 2(direction) within-subject repeated measures ANOVAs. Tukey's Post-Hoc tests identified the location of significant differences.

Results

Trunk muscle activity was significantly higher during FrontS versus BackS regardless of VPAC condition. (IO: p=0.018, EO: p<0.001, ICL: p<0.001) VPAC increased performance time for both squat variations (p=.0011), which may be associated with decreased detrimental force potential on the lumbar spine and knees. VPAC led to improved ability to maintain a neutral lumbar spine during both squat variations. This finding is associated with decreased detrimental force potential on the lumbar spine.

Conclusions

Findings could help guide practitioners and coaches to choose squat variations and incorporate VPAC strategies during their treatments and/or training programs.

Level of Evidence

Level 3©The Author(s).

Interaction of breathing pattern and posture on abdominal muscle activation and intra-abdominal pressure in healthy individuals: a comparative cross-sectional study

We aimed to assess the effects of interaction between several breathing patterns and postures on abdominal muscle activation and intra-abdominal pressure (IAP). This comparative cross-sectional study enrolled fourteen healthy university students majoring in sports science and/or physical education. They performed four active breathing tasks: quiet nasal breathing (Q-Bre), nasal deep breathing (Deep-Bre), completely forced expiration (Forced-Expi), and exertional nasal inhalation with abdominal muscles with isometric contraction (Exertion-Inspi) in the elbow-toe plank and supine postures. Breathing volume; IAP; and transverse abdominis-internal oblique muscle (TrA-IO) and external oblique muscle (EO) activities were recorded. Abdominal muscle activity and IAP significantly interacted with breathing pattern and postures during the expiratory phase (p < 0.05). In the inspiratory phase, TrA-IO activity was significantly affected by breathing pattern and EO activity with posture (p < 0.05). TrA-IO activity significantly increased during Forced-Expi in the supine posture (47.6% of the maximum voluntary contraction) and Exertion-Inspi in the elbow-toe posture (35.7%), whereas no differences were found during Deep-Bre or Q-Bre (< 20%). EO activity increased in the elbow-toe posture (22.5-30.6%) compared with that in the supine posture (< 5%) during all breathing tasks. IAP values were low during all tasks (< 15%) except for Forced-Expi (24.9%). Abdominal muscle activation and IAP interacted with the breathing pattern and posture.

Urinary Incontinence in Competitive Women Weightlifters

ABSTRACT

Wikander, L, Kirshbaum, MN, Waheed, N, and Gahreman, DE. Urinary incontinence in competitive women weightlifters. J Strength Cond Res 36(11): 3130-3135, 2022-Urinary incontinence has the potential to diminish athletic performance and discourage women from participating in sport and exercise. This study determined the prevalence and possible risk factors for urinary incontinence in competitive women weightlifters. This research was a cross-sectional, survey-based study completed by 191 competitive women weightlifters. The frequency and severity of urinary incontinence was determined using the Incontinence Severity Index. Urinary incontinence was defined as an Incontinence Severity Index score >0. The survey questions focused on risk factors, the context and triggers for urinary incontinence, and self-care strategies. Approximately, 31.9% of subjects experienced urinary incontinence within 3 months of completing the survey. Incontinence Severity Index scores were significantly correlated with parity ( r = 0.283, p = 0.01) and age ( r = 0.216, p = 0.01). There was no significant correlation between the Incontinence Severity Index score and the number of years participating in any form of resistance training ( r = -0.010, p = 0.886) or weightlifting ( r = -0.045, p = 0.534), body mass index ( r = 0.058, p = 0.422), or competition total ( r = -0.114, p = 0.115). The squat was the most likely exercise to provoke urinary incontinence. Although the number of repetitions, weight lifted, body position, and ground impact may increase the likelihood of urinary incontinence occurring during a lift, it is difficult to determine which factor has the greatest influence. Some self-care strategies used by competitive women weightlifters who experience urinary incontinence, such as training while dehydrated, have the potential to diminish athletic performance.

Validation and comparison of trunk muscle activities in male participants during exercise using an innovative device and abdominal bracing maneuvers

BACKGROUND

Abdominal bracing is effective in strengthening the trunk muscles; however, assessing performance can be challenging. We created a device for performing abdominal trunk muscle exercises. The effectiveness of this device has not yet been evaluated or comparedOBJECTIVE: We aimed to quantify muscle activity levels during exercise using our innovative device and to compare them with muscle activation during abdominal bracing maneuvers.

METHODS

This study included 10 men who performed abdominal bracing exercises and exercises using our device. We measured surface electromyogram (EMG) activities of the rectus abdominis (RA), external oblique, internal oblique (IO), and erector spinae (ES) muscles in each of the exercises. The EMG data were normalized to those recorded during maximal voluntary contraction (%EMGmax).

RESULTS

During the bracing exercise, the %EMGmax of IO was significantly higher than that of RA and ES (p< 0.05), whereas during the exercises using the device, the %EMGmax of IO was significantly higher than that of ES (p< 0.05). No significant difference was observed in the %EMGmax of any muscle between bracing exercises and the exercises using the device (p= 0.13-0.95).

CONCLUSIONS

The use of our innovative device results in comparable activation to that observed during abdominal bracing.

The influence of speed and strength abilities on the overall endurance of children aged 13-14 years with different typologies

AIM: The aim of this study was to determine the effect of a set of speed-strength exercises on the development of general endurance in schoolchildren aged 13–14, taking into account the differentiated load. METHODS: The pedagogical experiment was conducted on the basis of secondary school 60 in Kirov, Russia. The study involved 40 schoolchildren from the 7th grade, who were differentiated into the control and experimental groups of 20 people in each class. Children from the control group (CG) were engaged in physical education according to the standard program, and children from the experimental group additionally performed exercises for the development of speed and strength abilities with different loads. The strength of the nervous system was determined by tapping test, speed-strength abilities were determined by tests – flexion and extension of the arms at the stop while lying on the floor, long jump from a place with a push with two legs, and lifting the torso from the supine position. Overall endurance was determined by the “3 km ski run” test. RESULTS: In the CG, there was an improvement of only 2–4%. In the experimental group, there were significant improvements of 11–16%. CONCLUSION: I f schoolchildren perform exercises for the development of speed and strength abilities at physical education classes at school every time, then not only the indicators of these abilities will improve, but also the indicators of the overall endurance of children aged 13–14 will improve. Our results allow us to supplement the standard physical education program at school and effectively develop the physical qualities of schoolchildren aged 13–14.

Comparison of Abdominal Muscle Thickness between the Abdominal Draw-in Maneuver and Maximum Abdominal Contraction Maneuver

All abdominal muscles, including the transverse abdominis (TrA), should be modulated to improve core stability. This study aimed to investigate easier and more effective core exercise methods by comparing thickness changes in the TrA, internal oblique (IO), external oblique (EO), and rectus abdominis (RA) muscles during the abdominal draw-in maneuver (ADIM) and maximum abdominal contraction maneuver (MACM). Thirty healthy subjects who participated in this study underwent ADIM and MACM three times in random order. We measured the abdominal muscle thickness during ADIM and MACM using ultrasonography and compared the changes in the thickness of TrA, IO, EO, and RA muscles using a paired t-test. Significant differences were observed in the thicknesses of all the abdominal muscles between the ADIM and MACM groups (p < 0.05). The MACM immediately increased the thickness of the TrA (p < 0.001, effect size (ES) = 0.931), IO (p = 0.001, ES = 0.761), EO (p = 0.008, ES = 0.415), and RA (p < 0.001, ES = 0.767) muscles. These results suggest that MACM is useful for immediately increasing the thickness of TrA, IO, EO, and RA muscles and may contribute to the clinical effect of simultaneous contractions on the changes in abdominal muscle thickness.

Effect of Interventions for Improving Lumbar Motor Control on Low Back Pain in Sedentary Office Workers: A Randomized Controlled Trials

OBJECTIVE

To clarify the effect of intervention with dynamic motor control exercise (DMCE) for the lumbar region on low back pain in sedentary office workers (SOWs).

METHODS

The participants comprised 32 SOWs with low back pain who were randomly categorized into two groups: the DMCE group and the normal trunk exercise (NTE) group. Both groups performed each exercise for three days per week for 8 weeks. The primary endpoints were evaluated for the lumbar and hip flexion angles during trunk forward bending, effect of low back pain on activities of daily living (using the Oswestry Disability Index), and intensity of low back pain (using the Visual Analog Scale) pre- and post-intervention. The extent of changes was calculated by subtracting the pre-intervention value from the post-intervention value and was compared between the two groups using an unpaired t-test.

RESULTS

The extent of changes in the lumbar flexion and hip flexion angles at 10° of trunk forward bending were significantly greater in the DMCE group than in the NTE group, and no significant differences were noted between the two groups at other angles of trunk forward bending. The extent of changes in the Oswestry Disability Index and the Visual Analog Scale scores were significantly greater in the DMCE group than in the NTE group.

CONCLUSION

DMCE is effective in improving motor control in the lumbar region and hip joints, thereby ameliorating low back pain in SOWs.

NEUROMUSCULAR MECHANISMS AND EFFECTS OF CORE STABILIZATIONS ON TRUNK AND HIP MUSCLE ACTIVITY DURING LIFTING MOVEMENT

While the presence of lumbopelvic-hip stabilization has been provided as an importance component of the intra-abdominal pressure and dynamic spinal stabilization prior to movement, no previous study has investigated the effects in nonsymptomatic adults. This study investigated neuromuscular mechanisms and effects by comparing the natural core stabilization (NCS), abdominal bracing stabilization (ABS), and coordinated core stabilization (CCS) techniques in nonsymptomatic adults during lifting movement. A convenience sample of 40 nonsymptomatic adults (mean [Formula: see text] standard deviation, [Formula: see text]; 27 males, 13 females) were randomized into the NCS, ABS, and CCS techniques during lifting movement. The clinical outcomes included the deep and local (transverse abdominis (TrA), internal oblique (IO), and gluteus maximus (Gmax)) and superficial and global muscle (thoracic erector spinae (TES), lumbar erector spinae (LES), and external oblique (EO)) activation and balance ratios (IO/LES and Gmax/LES) and onset time co-activation ratios (IO/LES and Gmax/LES). One-way repeated-measures analysis of variance (ANOVA) and Bonferroni correction revealed that the IO/LES and Gmax/LES balance and activation ratios were greater in CCS than in NCS and ABS. The onset time co-activation ratio was improved in CCS as compared with NCS and ABS, and ABS dropped equally inversely to NCS. Our results provide novel therapeutic evidence that CCS-based lifting movement is more balanced or coordinated in terms of neuromuscular control than the other techniques and may be used as an alternative exercise for core stabilization.

Does Intra-abdominal Pressure Have a Causal Effect on Muscle Strength of Hip and Knee Joints?

ABSTRACT

Tayashiki, K, Kanehisa, H, and Miyamoto, N. Does intra-abdominal pressure have a causal effect on muscle strength of hip and knee joints? J Strength Cond Res 35(1): 41-46, 2021-It remains unclear whether intra-abdominal pressure (IAP) has a causal effect on lower-limb muscle strength. This study aimed to clarify whether or not changes in IAP, induced by changing breathing state, influence muscle strength of hip and knee extensor and flexor. Eighteen healthy males (age: 22.0 ± 2.2 years, height: 1.71 ± 0.03 m, and body mass: 68.1 ± 6.1 kg) performed maximal voluntary isometric contractions (MVICs) of hip and knee extensor and flexor during breath-hold at full inspiration (inspiratory condition) or expiration (expiratory condition), or during normal breath-hold (normal condition). Intra-abdominal pressure was obtained by a pressure transducer placed in the rectum and determined at the time at which the developed torque reached to the maximum. The IAP during each MVIC was significantly greater in inspiratory condition than in expiratory condition (p < 0.05). The maximal torque of hip extensor was significantly greater in inspiratory condition than in expiratory condition (p < 0.05). By contrast, the maximal torque of each of hip flexor, knee extensor, and knee flexor was not different among the 3 breath-hold conditions. The IAP was significantly correlated with the maximal torque of hip extensor in each breath-hold condition. The current results suggest that a sufficient increase in IAP has a causal effect to specifically improve muscle strength of hip extensor.

Effect of the Abdominal Draw-In Maneuver and Bracing on Abdominal Muscle Thickness and the Associated Subjective Difficulty in Healthy Individuals

We evaluated the trunk abdominal muscle thickness while performing different exercises to identify the most effective training and to investigate the subjective difficulty associated with exercising. Twenty-eight men (mean age: 21.6 ± 0.9 years) without orthopedic diseases were enrolled. Ultrasonic imaging was used to measure the thickness of the transversus abdominis (TA), internal oblique, and external oblique muscles while at rest and while performing the abdominal draw-in maneuver and abdominal bracing. Measurements were made in the supine and sitting positions, and the subjective difficulty in performing each exercise was examined using a 5-level evaluation scale. The TA and internal oblique muscle thicknesses were significantly greater during the abdominal draw-in maneuver (ADIM) than during bracing or resting, in the supine and sitting positions. The subjective difficulty of abdominal bracing (AB) was graded significantly higher than that of ADIM. Additionally, a correlation between subjective difficulty and muscle thickness was found for the TA and IO. Our results may contribute to the choice of more effective exercises for spinal stability.

Experimentally induced low back pain influences brain networks activity

Purpose of this study was to answer the question whether the recognized patterns of brain activity are likely to change under the influence of experimentally induced low back pain (LBP), and also to determine the functional networks of the brain engaged in this process. Twenty healthy subjects (8 women) participated. An experimental design was applied with repeated measurements of the blood oxygen level-dependent (BOLD) signal from the brain during two different voluntary contractions of the abdominal muscles without and with experimentally induced LBP. Brain areas showing significant differences in activity were identified and ascribed to the three functional neuronal brain networks: default mode network (DMN), pain matrix (PM), and sensorimotor (SM) areas. After implementation of the experimental painful stimulus the overall level of brain activity appears to be higher. No higher brain deactivations are seen in painful conditions and no higher activations in pain-free conditions. During isolated-type of muscular contraction a slight tendency to DMN deactivation may be observed.

Differences in Activity of the Brain Networks During Voluntary Motor Tasks Engaging the Local and Global Muscular Systems of the Lower Trunk

Low back pain constitutes a multidimensional problem of largely unknown origin. One of the recent theories explaining its frequent occurrence includes speculative statements on patterns of central nervous system activity associated with the control of so-called local and global muscles of the lower trunk. The objective of the study was to verify whether there is a difference in the activity of the brain during selective, voluntary contraction of the local and global abdominal muscles as assessed by functional MRI. Twenty healthy subjects participated. An experimental design was applied with repeated measurements of the blood-oxygen-level-dependent signal from the brain during voluntary contraction of the local and global abdominal muscles, performed in random order. Prior to registration, a 2-week training period was introduced, aiming to master the experimental motor tasks. The magnetic resonance imaging (MRI) data were processed using the FMRIB Software Library (Oxford, UK). Brain areas showing significant activations/deactivations were identified and averaged across all participants, and intercondition differential maps were computed. Areas of significant intercondition differences were linked to the corresponding anatomical structures and ascribed to the default mode functional brain network and to the sensorimotor network. Contraction of the local abdominal muscles elicited more pronounced activity of the brain cortex, basal ganglia, and cerebellum. This suggests that motor control of the abdominal musculature consists of two modes of brain activity and that control of the local muscles may be a more challenging task for the brain. Moreover, contraction of the local muscles elicited more distinct deactivation of the default mode network, which may have implications for diagnostics and therapy of low back pain.

Reduction of Knee Pain in a 45-Year-Old Woman After Pelvic Manipulation and Kinesiology Taping: A Case Report

Objective

The purpose of this case report is to describe the chiropractic management of a patient with knee pain stemming from pelvic imbalance.

Clinical Features

A female patient presented to a chiropractic clinic with ongoing anteromedial knee pain whenever she walks. The patient reported being unable to walk a half mile without her knee feeling like it would "give out."

Intervention and Outcome

The patient received 5 treatments focusing on the pelvic imbalance and reduced muscle strength discovered in the patient's initial evaluation. Chiropractic manipulation of the sacroiliac joint, kinesiology taping, and gluteus medius exercises were administered. The Verbal Rating Scale, muscle strength assessment, and orthopedic evaluation measured the patient's progress. After 5 treatments the Verbal Rating Scale went from 8 to 1 and gluteus medius strength scored 5 of 5.

Conclusion

The patient in this case reported resolution of her knee pain after 5 treatments over the course of 10 days. The patient reported no pain while walking nor while performing other activities of daily living. Although this is one case, correcting pelvic balance via conservative measures resolved the knee pain. Implementing therapy proximal to the complaint may be a viable option for patients with knee pain.

Protocol for Minute Calisthenics: a randomized controlled study of a daily, habit-based, bodyweight resistance training program

BACKGROUND

Resistance-training (RT) provides significant health benefits. However, roughly 3/4 of adults in the United States do not meet current Physical Activity Guidelines in this regard. There has been a call for research examining the effectiveness of interventions to increase participation in physical activity and to better understand the dose response relationship upon health outcomes. Studies are needed that assess the effectiveness of RT programs that are time-efficient and simple to perform. This fully-powered, randomized controlled study will assess a habit-based RT program consisting of one set of push-ups, angled-rows, and bodyweight-squats performed every weekday for 12-24 weeks in untrained individuals.

METHODS

Forty-60 untrained osteopathic medical students and college/university employees who work in an office setting will be recruited and randomized (1:1) to an intervention or waitlist control group. After 12-week follow-up assessment, the intervention group will continue the program and the control group will initiate the program for 12 weeks. In addition to the equipment and training needed to safely perform the exercises, all participants will receive training in the Tiny Habits® Method (THM) and digital coaching for the duration of the study. Participants will complete weekly assessments regarding the program during their initial 12-week intervention phase. The primary outcome is the change from baseline to 12 weeks in the intervention group versus the control group, in the combined number of repetitions performed in one set of each of the three exercises (composite repetitions) under a standardized protocol. Secondary outcomes include adherence to and satisfaction with the program, and change from baseline to 12- and 24-week follow-up in blood pressure, fasting lipid panel, hemoglobin A1c, body mass index, anthropometry, body composition, mid-thigh muscle thickness, and habit strength.

DISCUSSION

This study will evaluate a simple, habit-based RT intervention in untrained individuals. The approach is unique in that it utilizes brief but frequent bodyweight exercises and, via the THM, focuses on consistency and habit formation first, with effort being increased as participants are motivated and able. If effective, the program can be easily scaled for wider adoption.

TRIAL REGISTRATION

This study was prospectively registered at ClinicalTrials.gov, identifier NCT04207567 , on December 23rd, 2019.

Comparisons of Resistance Training and "Cardio" Exercise Modalities as Countermeasures to Microgravity-Induced Physical Deconditioning: New Perspectives and Lessons Learned From Terrestrial Studies

Prolonged periods in microgravity (μG) environments result in deconditioning of numerous physiological systems, particularly muscle at molecular, single fiber, and whole muscle levels. This deconditioning leads to loss of strength and cardiorespiratory fitness. Loading muscle produces mechanical tension with resultant mechanotransduction initiating molecular signaling that stimulates adaptations in muscle. Exercise can reverse deconditioning resultant from phases of detraining, de-loading, or immobilization. On Earth, applications of loading using exercise models are common, as well as in μG settings as countermeasures to deconditioning. The primary modalities include, but are not limited to, aerobic training (or "cardio") and resistance training, and have historically been dichotomized; the former primarily thought to improve cardiorespiratory fitness, and the latter primarily improving strength and muscle size. However, recent work questions this dichotomy, suggesting adaptations to loading through exercise are affected by intensity of effort independent of modality. Furthermore, similar adaptations may occur where sufficient intensity of effort is used. Traditional countermeasures for μG-induced deconditioning have focused upon engineering-based solutions to enable application of traditional models of exercise. Yet, contemporary developments in understanding of the applications, and subsequent adaptations, to exercise induced muscular loading in terrestrial settings have advanced such in recent years that it may be appropriate to revisit the evidence to inform how exercise can used in μG. With the planned decommissioning of the International Space Station as early as 2024 and future goals of manned moon and Mars missions, efficiency of resources must be prioritized. Engineering-based solutions to apply exercise modalities inevitably present issues relating to devices mass, size, energy use, heat production, and ultimately cost. It is necessary to identify exercise countermeasures to combat deconditioning while limiting these issues. As such, this brief narrative review considers recent developments in our understanding of skeletal muscle adaptation to loading through exercise from studies conducted in terrestrial settings, and their applications in μG environments. We consider the role of intensity of effort, comparisons of exercise modalities, the need for concurrent exercise approaches, and other issues often not considered in terrestrial exercise studies but are of concern in μG environments (i.e., O2 consumption, CO2 production, and energy costs of exercise).

Variables Affecting Intra-abdominal Pressure During Lifting in the Early Postpartum Period

OBJECTIVES

Intra-abdominal pressure (IAP) may contribute to pelvic floor health, although the direction and magnitude of such an effect, if any, are not yet known. Identifying individual characteristics, and in particular modifiable factors, associated with higher IAP during recovery from vaginal childbirth might serve to mitigate early pelvic floor dysfunction. The aim of this study was to identify characteristics associated with maximal IAP during lifting in postpartum primiparous women who delivered vaginally.

METHODS

At 6 to 10 weeks postpartum, we measured maximal IAP, assessed via an upper vaginal sensor, as participants (enrolled in an ongoing cohort study) lifted a weighted car seat (12.5 kg). We evaluated whether the following independent variables were associated with maximal IAP: age, ethnicity, body mass index, height, abdominal circumference, weight gain during pregnancy, lifting time, breath holding during lifting, lifting technique, measures of muscular fitness, and days since delivery.

RESULTS

In the 206 participants, weight, waist circumference, body mass index, and days since delivery were positively associated with mean maximal IAP during lifting, whereas IAP decreased as height increased. As the duration of the lifting task increased, mean maximal IAP during lifting also increased, but there were no associations between lifting technique or breath holding during lifting and IAP. Neither pelvic floor muscle strength nor abdominal muscle endurance was associated with IAP during lifting.

CONCLUSIONS

Other than measures of body habitus and lifting duration, we did not identify modifiable factors that could mitigate maximal pressures experienced by the pelvic floor during the early postpartum period.

Progressive Respiratory Muscle Training for Improving Trunk Stability in Chronic Stroke Survivors: A Pilot Randomized Controlled Trial

BACKGROUND

Stroke weakens the respiratory muscles, which in turn may influence the trunk stability; it is unclear whether the progressive respiratory muscle training (RMT) is effective in improving the trunk stability. The aim of this study was to investigate the effects of progressive RMT with trunk stabilization exercise (TSE) on respiratory muscles thickness, respiratory muscle functions, and trunk stability in chronic stroke survivors.

METHODS

This is a pilot randomized controlled trial. Chronic stroke survivors (n = 33) who were able to sit independently participated in the tstudy. The participants were allocated into the RMP with TSE group or the TSE group. The respiratory muscle thickness during resting and contraction were measured. Maximal expiratory pressure (MEP), peak expiratory flow (PEF), and forceful expiratory volume at 1 sec (FEV1) for forced expiratory muscle function and maximal inspiratory pressure (MIP), peak inspiratory flow (PIF), and vital capacity (VC) for inspiratory muscle function were examined. Trunk stability was estimated by maximal velocity and path length of the center of pressure (COP) by using a balance board with sitting posture.

RESULTS

The respiratory muscle thickness was significantly increased on the affected side in the RMT group than in the TSE group. The MEP, PEF, MIP, and PIF were significantly increased in the RMT group than in the TSE group; however, FEV1 and VC showed no significant differences between the 2 groups. Trunk stability for the maximal velocity of COP of extension and affected side bending was significantly increased in the RMT group than in the TSE group. In addition, the maximal path length of COP of flexion, extension, affected/less affected side bending was significantly increased in the RMT group than in the TSE group.

CONCLUSIONS

RMT combined with TSE can be suggested as an effective method to improve the respiratory muscle thickness, respiratory muscle functions, and trunk stability in chronic stroke survivors as opposed to TSE only.

Volitional Preemptive Abdominal Contraction and Upper Extremity Muscle Latencies During D1 Flexion and Scaption Shoulder Exercises

CONTEXT

The abdominal-bracing maneuver, a volitional preemptive abdominal contraction (VPAC) strategy, is commonly used during resisted shoulder exercises. How VPAC affects shoulder-muscle function during resisted shoulder exercise is unknown.

OBJECTIVE

To identify the effects of VPAC on selected parascapular and glenohumeral muscles during specific shoulder exercises with or without resistance.

DESIGN

Cross-sectional study.

SETTING

Clinical biomechanics research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty-two asymptomatic volunteers between 18 and 40 years of age.

INTERVENTION(S)

Participants performed arm elevation in scaption and D1 shoulder-flexion (D1F) patterns with and without resistance and VPAC.

MAIN OUTCOME MEASURE(S)

Electromyography was used to test the muscle-contraction amplitudes and onset timing of the anterior deltoid, posterior deltoid, upper trapezius, lower trapezius, and serratus anterior. Muscle-response amplitudes were quantified using root mean square electromyography. Shoulder-muscle relative-onset timing was quantified in reference to kinematic elbow-movement initiation.

RESULTS

The VPAC increased serratus anterior amplitude during D1F ( P < .001) and scaption ( P < .001) and upper trapezius amplitude ( P < .001) in scaption. All muscle amplitudes increased with resistance. The VPAC decreased muscle-onset latencies for the anterior deltoid ( P < .001), posterior deltoid ( P = .008), upper trapezius ( P = .001), lower trapezius ( P = .006), and serratus anterior ( P = .001) during D1F. In addition, the VPAC decreased muscle-onset latencies for the anterior deltoid ( P < .001), posterior deltoid ( P = .007), upper trapezius ( P < .001), lower trapezius ( P < .001), and serratus anterior ( P < .001) during scaption.

CONCLUSIONS

The VPAC affected only the parascapular muscles that had the greatest scapular-stabilizing roles during the specific open chain movement we tested. It decreased latencies in all muscles. These neuromuscular changes may enhance the stability of the shoulder during D1F and scaption exercises.

Decreased Respiratory Muscle Function Is Associated with Impaired Trunk Balance among Chronic Stroke Patients: A Cross-sectional Study

The abdominal muscles play a role in trunk balance. Abdominal muscle thickness is asymmetrical in stroke survivors, who also have decreased respiratory muscle function. We compared the thickness of the abdominal muscles between the affected and less affected sides in stroke survivors. In addition, the relationship between respiratory muscle function and trunk balance was evaluated. Chronic stroke patients (18 men, 15 women; mean age, 58.94 ± 12.30 years; Mini-Mental Status Examination score ≥ 24) who could sit without assist were enrolled. Abdominal muscle thickness during rest and contraction was measured with ultrasonography, and the thickening ratio was calculated. Respiratory muscle function assessment included maximum respiratory pressure, peak flow, and air volume. Trunk function was evaluated using the Trunk Impairment Scale, and trunk balance was estimated based on the center of pressure velocity and path length within the limit of stability in sitting posture. Abdominal muscles were significantly thinner on the affected side, and the thickening ratio was lower in the affected side (P < 0.05). In addition, the higher thickening ratio of the affected side showed significant relationship with higher trunk function. Moreover, higher respiratory muscle function was significantly correlated with higher level of trunk function and balance in stroke patients (P < 0.05). Thus, chronic stroke survivors have decreased abdominal muscle thickness on the affected side, and respiratory muscle function has positive correlation with trunk function and balance. We propose that respiratory muscle training should be included as part of trunk balance training in chronic stroke patients.

Causal effect of intra-abdominal pressure on maximal voluntary isometric hip extension torque

PURPOSE

Intra-abdominal pressure (IAP) has been recently shown to be associated specifically with maximal voluntary isometric contraction (MVC) torque of hip extension, although the causal relationship remains unclear. The present study aimed to elucidate whether IAP has a causal effect on hip extension MVC torque.

METHODS

IAP during hip extension MVC was changed by controlling the lung volume (i.e., depth of inspiration). Twelve healthy males conducted MVCs of hip extension during breath-hold at full inspiration (inspiratory condition) or expiration (expiratory condition), or during normal breath-hold (normal condition). IAP during MVCs was measured a pressure transducer placed in the rectum.

RESULTS

The IAP during hip extension MVC was significantly higher in inspiratory condition (132.0 ± 46.1 mmHg) than in the other two conditions and also higher in normal condition (104.6 ± 35.9 mmHg) than in expiratory condition (77.0 ± 39.1 mmHg). The hip extension MVC torque was significantly higher in inspiratory condition (297.7 ± 82.7 N m) than in expiratory condition (266.4 ± 84.5 N m). In each condition, the hip extension MVC torque correlated with IAP during the MVC task.

CONCLUSION

The current results suggest that IAP has a positive causal effect on hip extension MVC torque and that a sufficient increase in IAP directly leads to an enhancement of hip extension MVC torque.

Effect of Core Training on Trunk Flexor Musculature in Male Soccer Players

The present study aimed to elucidate the effect of core training on trunk flexor musculature in athletes. Twenty-eight collegiate male soccer players were randomly assigned to three groups: a training group that performed core exercises with wheeled platforms (WP), a training group that performed body mass-based core exercise (BME), and a control group that did not perform core exercise training (CON). WP and BME trained twice a week for 10 weeks. The WP performed 8–14 exercises with wheeled platforms. BME conducted four core exercises to failure. Before and after the intervention, trunk segment lean body mass (LBM) was measured using a whole-body dual-energy X-ray absorptiometry scanner. Muscle thicknesses (MTs) of the rectus abdominis (RA), external oblique, internal oblique (IO), and transverse abdominis were determined with an ultrasound apparatus. No significant changes for any measured variables were found in CON. In both training groups, the trunk segment LBM was significantly increased through the intervention. While MT for IO significantly increased in the two training groups, significant increases in MT for RA were found in only WP. For collegiate soccer players, the core training programs adopted here can be effective in increasing trunk segment LBM, but the effectiveness on the trunk flexor muscularity differs between the two training modalities.

Comparison of abdominal muscle activity during abdominal drawing-in maneuver combined with irradiation variations

Many experts have used an indirect method for enhancing strength and performance of muscles in clinical practice. The indirect method, which called an irradiation is a basic procedure of proprioceptive neuromuscular facilitation, there is little research related the effects of irradiation. This study investigated abdominal muscle activity during abdominal drawing-in maneuver (ADIM) combined with irradiation variations. The study recruited 42 healthy, young adults who were divided randomly into three groups according to which intervention they received. The first group performed the ADIM combined with coactivation of the pelvic floor muscle. The second group performed the ADIM combined with the irradiation resulting from dorsiflexion of the ankle. The third group performed the ADIM combined with the irradiation resulting from bilateral arm extension. Electromyography data were collected from the rectus abdominis, external oblique abdominis, and transversus abdominis/internal oblique abdominis (TrA/IO) muscles during ADIM combined with irradiation variations. There were significant differences in the abdominal muscle activity and the preferential contraction ratio of the TrA/IO among the three groups (P<0.05). ADIM combined with irradiation resulting from bilateral arm extension may be effective for enhancing the deep and superficial abdominal muscles of healthy people and athletes. The ADIM without the irradiation is advantageous for recovering motor control of the TrA/IO.

Associations of maximal voluntary isometric hip extension torque with muscle size of hamstring and gluteus maximus and intra-abdominal pressure

PURPOSE

Muscle size of the hamstring and gluteus maximus (GM) as well as intra-abdominal pressure (IAP) are considered as factors affecting the torque development during hip extension. This study examined the associations of torque development during maximal voluntary isometric hip extension with IAP and muscle size of the hamstring and GM.

METHODS

Anatomical cross-sectional area (ACSA) of the hamstring and thickness of GM were determined in 20 healthy young males using an ultrasonography apparatus (Experiment 1). Torque and IAP were simultaneously measured while subjects performed maximal voluntary isometric hip extension. The IAP was measured using a pressure transducer placed in the rectum and determined at the time at which the developed torque reached to the maximal. In Experiment 2, torque and IAP were measured during maximal voluntary isometric hip flexion in 18 healthy young males.

RESULTS

The maximal hip extension torque was significantly correlated with the IAP (r = 0.504, P = 0.024), not with the ACSA of the hamstring (r = 0.307, P = 0.188) or the thickness of GM (r = 0.405, P = 0.076). The relationship was still significant even when the ACSA of the hamstring and the thickness of GM were adjusted statistically (r = 0.486, P = 0.041). The maximal hip flexion torque was not significantly correlated with the IAP (r = -0.118, P = 0.642).

CONCLUSION

The current results suggest that IAP can contribute independently of the muscle size of the agonists to maximal voluntary hip extension torque.