Natural breath control during lifting tasks: effect of load

The effect of abdominal bracing on respiration during a lifting task: a cross-sectional study

BACKGROUND

Abdominal bracing is a maneuver widely used by rehabilitation specialists and sports trainers to improve spinal stability. This study aimed to investigate how lifting tasks with and without abdominal bracing affect the respiratory function of the diaphragm.

METHODS

M-mode ultrasonographic assessment of diaphragmatic motion combined with spirometry was performed on 31 healthy adults. Participants were asked to breathe continuously whilst lifting a load with spontaneous abdominal muscle contraction (natural loaded breathing) and abdominal bracing (AB loaded breathing).

RESULTS

Pearson's correlations revealed strong correlations between ultrasonography and spirometry measures (p < 0.001) for all types of breathing: tidal breathing (r = 0.709, r2 = 0.503), natural loaded breathing (r = 0.731, r2 = 0.534) and AB loaded breathing (r = 0.795, r2 = 0.632). Using paired-samples t-tests, the natural loaded breathing ultrasonography revealed more caudal diaphragm positions during inspiration (p < 0.001) but not during expiration (p = .101). Spirometry demonstrated lower lung volumes (L) at the end of inspiration and expiration (p < 0.001), with no changes in total lung volume (p = 0.06). The AB loaded breathing ultrasonography revealed more caudal diaphragm positions during inspiration (p = 0.002) but not during expiration (p = 0.05). Spirometry demonstrated lower lung volumes at the end of inspiration (p < 0.001), expiration (p = 0.002), and total lung volumes (p = 0.019).

CONCLUSION

This study demonstrated that abdominal bracing performed during a lifting task reduces lung volume despite an increase in diaphragmatic motion. Diaphragm excursions strongly correlate with lung volumes even under postural loading.

TRIAL REGISTRATION

The study was prospectively registered on 8 April 2021 at ClinicalTrials.gov with identification number NCT04841109.

Face Masks at the Gymnasium: Physiological Responses and Mechanical Performance Are Not Compromised by Wearing Surgical or Filtering Facepiece 2 Masks in Healthy Subjects

ABSTRACT

Rial-Vázquez, J, Nine, I, Guerrero-Moreno, JM, Rúa-Alonso, M, Fariñas, J, Márquez, G, Giráldez-García, MA, Méndez-Bouza, KY, López-Pillado, H, Coutado-Sánchez, E, Losada-Rodríguez, A, and Iglesias-Soler, E. Face masks at the gym: physiological responses and mechanical performance are not compromised by wearing surgical or filtering facepiece 2 masks in healthy subjects. J Strength Cond Res 37(7): 1404-1410, 2023-This study explored the effects of wearing 2 types of face masks on mechanical performance and physiological responses during high-intensity resistance exercise. Twelve healthy men performed 3 workout protocols in a randomized order: wearing a surgical or filtering facepiece 2 (FFP2) mask or without a mask. Each workout consisted of 3 sets of 10 repetitions of bench press (BP) and parallel squat (SQ) with a 12 repetition maximum load, including 2 minutes of recovery between sets and exercises. Mechanical performance was evaluated through the mean propulsive velocity and the number of repetitions completed during each session. Physiological responses were the oxygen saturation (SpO2), blood lactate concentration, heart rate (HR), and HR variability. Perceived exertion was recorded after each set, and The Beck Anxiety Inventory scale was completed at the end of each workout. The number of repetitions completed and the session mean propulsive velocity {(BP [m·s-1]: surgical: 0.35 ± 0.05; FFP2: 0.36 ± 0.04; nonmask: 0.38 ± 0.06) and (SQ: surgical: 0.43 ± 0.05; FFP2: 0.40 ± 0.07; nonmask: 0.41 ± 0.05)} were similar between conditions (p > 0.05). Heart rate recorded during sessions was similar across conditions: surgical: 119 ± 14, FFP2: 117 ± 13, and nonmask: 118 ± 10 bpm (p = 0.919). Face masks had no effect on SpO2, blood lactate concentration, HR variability, perceived exertion, and anxiety values (p > 0.05). Face masks do not compromise strength performance, physiological parameters, and perceived comfort of young and healthy individuals during a high-intensity resistance training session.

Postural-respiratory function of the diaphragm assessed by M-mode ultrasonography

OBJECTIVES

The diaphragm changes position and respiratory excursions during postural loading. However, it is unclear how it reacts to lifting a load while breath-holding or breathing with simultaneous voluntary contraction of the abdominal muscles (VCAM). This study analyzed diaphragm motion in healthy individuals during various postural-respiratory situations.

METHODS

31 healthy participants underwent examination of the diaphragm using M-mode ultrasonography, spirometry, and abdominal wall tension (AWT) measurements. All recordings were performed simultaneously during three consecutive scenarios, i.e., 1. Lifting a load without breathing; 2. Lifting a load and breathing naturally; 3. Lifting a load and breathing with simultaneous VCAM.

RESULTS

Using paired-samples t-tests, lifting a load without breathing displaced the diaphragm's expiratory position more caudally (P < .001), with no change noted in the inspiratory position (P = .373). During lifting a load breathing naturally, caudal displacement of the diaphragm's inspiratory position was presented (P < .001), with no change noted in the expiratory position (P = 0.20) compared to tidal breathing. Total diaphragm excursion was greater when loaded (P = .002). Lifting a load and breathing with VCAM demonstrated no significant changes in diaphragm position for inspiration, expiration, or total excursion compared to natural loaded breathing. For all scenarios, AWT measures were greater when lifting a load (P < .001).

CONCLUSION

In healthy individuals, caudal displacement and greater excursions of the diaphragm occurred when lifting a load. The postural function of the diaphragm is independent of its respiratory activity and is not reduced by the increase in AWT.

Breathing, (S)Training and the Pelvic Floor—A Basic Concept

Background: The current scientific literature is inconsistent regarding the potential beneficial or deleterious effects of high-intensity physical activities on the pelvic floor (PF) in women. So far, it has not been established with certainty whether disparate breathing mechanisms may exert short- or long-term influence on the PF function in this context, although based on the established physiological interrelationship of breathing with PF activation, this seems plausible. Objective: To propose a basic concept of the influence of different breathing patterns on the PF during strenuous physical efforts. Methodical approaches: Review of the recent literature, basic knowledge of classical western medicine regarding the principles of muscle physiology and the biomechanics of breathing, additional schematic illustrations, and magnetic resonance imaging (MRI) data corroborate the proposed concept and exemplify the consequences of strenuous efforts on the PF in relation to respective breathing phases. Conclusion: The pelvic floor muscles (PFMs) physiologically act as expiratory muscles in synergy with the anterolateral abdominal muscles, contracting during expiration and relaxing during inspiration. Obviously, a strenuous physical effort requires an expiratory motor synergy with the PFM and abdominal muscles in a co-contracted status to train the PFM and protect the PF against high intra-abdominal pressure (IAP). Holding breath in an inspiratory pattern during exertion stresses the PF because the high IAP impinges on the relaxed, hence insufficiently protected, PFMs. It seems conceivable that such disadvantageous breathing, if performed regularly and repeatedly, may ultimately cause PF dysfunction. At any rate, future research needs to take into account the respective breathing cycles during measurements and interventions addressing PFM function.

The influence of different modes of ventilation on standing balance of athletes

Background:

The respiratory movements are one of the factors influencing standing balance. Although well-trained athletes have better postural performance compared to untrained men, it's not quite clear, if the formers' upright posture would be more stable during different ventilation modes, maximal voluntary hyperventilation and inspiratory breath-holding. There are no studies on this subject in the available literature.

Objectives:

The aim of this study was to investigate an influence of maximal inspiratory breath-holding and maximal voluntary hyperventilation on the standing balance of athletes.

Patients and Methods:

We assessed the amplitude and the velocity of postural sway in the athletes (n = 38) and untrained subjects (n = 28) by the force platform. The frequency characteristics of the center of pressure (CP) oscillations' were also analyzed. The amplitude and the frequency of respiratory movements were estimated by the strain gauge.

Results:

It was found that during quiet breath velocity and frequency of CP oscillations were lower in the athletes. Breath holding led to an increase of velocity and frequency of CP displacement in both groups, increase of these indices was more pronounced in the athletes. Maximal voluntary hyperventilation caused a significant increase of all stabilographic indices in both groups. Increase of frequency and amplitude of respiratory movements were mainly observed during hyperventilation in athletes and it caused an increase of the velocity of CP displacement. Changes of sway amplitude were the same in both groups.

Conclusions:

Breath holding led to activation of the postural control, which was more pronounced in the athletes. Hyperventilation caused an impairment of the postural stability. The athletes' postural system compensated the impact of hyperventilation more efficiently versus controls, but it was achieved at the expense of greater effort.

Breath control during a tiptoe task

Examination of naturally occurring respiration during postural challenges may increase our understanding of the factors linking respiration to lumbar segmental control. This study determined if the timing and magnitude of inhaled volume changes were related to mechanical events that challenge spinal stability during a tiptoe task. Thirty healthy individuals (15 male) had airflow recorded while they completed a tiptoe task which involved: moving onto tiptoe while reaching toward a hanging target (ascent); grasping and holding the target while maintaining the tiptoe position for 3 s (hold); and then returning to the start position (descent). The rate of airflow and amount of inhaled volume (normalized to vital capacity (%VC)) were identified at 13 different intervals spanning the ascent, hold and descent phase. Using repeated measures analysis of variance, significant main effects were identified for both rate of airflow (p < 0.001) and %VC (p < 0.001). Exploration of these main effects revealed that individuals tended to inspire and increase %VC during the ascent phase, hold their breath and maintain %VC during the hold phase when whole body balance is challenged, and exhale during the descent phase. These findings are congruent with theories suggesting that breath control is linked in predictable ways to potentially improve lumbar spine stiffness when presented with mechanical challenges during functional tasks.

Effect of airway control by glottal structures on postural stability

Maintenance of upright posture involves complex neuromotor processes that include control of thoracic and abdominal pressures. Control of airflow by glottal structures is a primary determinant of thoracic pressure and may have a role in control of postural stability. This study aimed to investigate the effect of modulation of airway control on upright postural stability during postural perturbations. Standing balance was gently perturbed in the sagittal plane during 7 breathing/voicing tasks that ranged from completely closed (breath-hold), to partially opened (voicing) or completely open (sigh) glottal conditions in 11 healthy adults. Dependent measures were peak amplitude of displacement of the thorax and center of pressure (CoP). When the glottis was completely open during sigh, thoracic displacement in response to the perturbation was greater than in all other conditions, regardless of direction of perturbation (post hoc, all P < 0.002). The absolute amplitude of CoP displacement was greater with backward perturbation (main effect, Direction P = 0.001) and was greater at both extremes of glottal modulation (glottis closed and completely open) than when the glottis was partially opened during counting out loud (post hoc, all P < 0.04). These results show that airway modulation affects postural control during upright perturbations. The thorax was more stable when the glottis was engaged than when it was required to remain open, whereas control of CoP displacement appeared more optimal during the natural dynamic mid-range airway modulation of voicing. These data suggest that glottal control influences balance, and that glottal control strategies may be an important consideration for patients with breathing and/or balance disorders.

Individuals with low back pain breathe differently than healthy individuals during a lifting task

STUDY DESIGN

Case control, repeated-measures, experimental laboratory study.

OBJECTIVE

To determine if, during a whole-body lifting task, individuals with low back pain (LBP) breathe differently than age-matched controls.

BACKGROUND

Breath control may be optimized to provide increased intersegmental control of the lumbar spine through the generation of intra-abdominal pressure. Consequently, impairments in respiratory and trunk muscle coordination during lifting tasks may contribute to the occurrence or maintenance of LBP.

METHODS

Participants without LBP (n = 30) were matched by gender and age with those presenting with chronic mechanical LBP (n = 32) of at least 1 year in duration. Participants completed a total of 8 self-paced lifts of a crate from the floor to a table, with the crate empty during 4 of the lifts and loaded to 25% of the participant's body weight during 4 of the lifts. The amount of volume in the lungs, measured as a percentage of the individual's vital capacity (%VC), was identified at 9 points during the lifting task. A 2 × 2 × 2 × 9 (group by gender by load by time) mixed-model analysis of covariance (ANCOVA), with age as the covariate, was used to identify differences among conditions and groups of %VC used during the lift.

RESULTS

Individuals with LBP performed the lifting task with more volume in their lungs (48.2 %VC) than healthy peers (40.9 %VC). Age significantly affected %VC used during the lift: with increasing age, participants with LBP increased inspired volume and participants without LBP decreased inspired volume.

CONCLUSIONS

Individuals with LBP performed a lifting task with more inhaled lung volume than individuals without LBP. These findings are consistent with the theoretical link between breath control, intra-abdominal pressure, and lumbar segmental control.

Breath control during manual free-style lifting of a maximally tolerated load

Clear evidence links voluntary breath control, intra-abdominal pressure and lumbar stability. However, little is known regarding optimal breath control during manual materials handling. No studies have examined natural breath control while lifting a maximal load. Fourteen healthy subjects lifted a loaded crate from the floor to a table while respiratory flow data were collected. The loads lifted began at 10% of body weight and increased up to 50% (if tolerated) by 5% increments. Data from the minimum, moderate and maximum loads were analysed. Uniform and consistent breath holding during lifting of a maximally tolerated load did not occur. Across all three loads, frequency of inspiration was highest immediately prior to lift-off and significantly higher inspired volume occurred at lift-off of the load compared with preparation for lifting. Holding the breath does not appear to be related to lifting of a maximally tolerated load from floor to table. STATEMENT OF RELEVANCE: The findings demonstrate that consistent patterns of naturally occurring breath control during lifting of a maximal load can be identified and do not include uniform breath holding. The findings may assist in creating models for optimal breath control, which will minimise risk of injury during manual material handling tasks.

Striatal projections of the vagal-responsive region of the thalamic parafascicular nucleus in macaque monkeys

We recently reported that the thalamic parafascicular nucleus (Pf) in monkeys is strongly activated by vagus nerve afferents. The main forebrain target of Pf is the striatum, but the specific striatal regions receiving visceral input via this pathway are unknown. We examined the projections of this region by injecting anterograde tracers into the vagus evoked potential (VEP) focus in Pf of macaque monkeys. The VEP was strongest lateral and anterior to the habenulointerpeduncular tract, but it was distributed across the entire horizontal extent of the ventral half of Pf. All injections produced labeled terminals in the caudate (Cd), especially the Cd tail and the adjacent ventral posterior Pu. Terminations occurred throughout the Cd head and body but spared the most anterior and dorsolateral parts. Injections in more anterior and lateral portions of Pf produced progressively more terminations in Pu, mainly in the precommissural region and the medial aspect of posterior Pu. Dual injections of different tracers revealed overlapping projections with interdigitated strands of striatal terminations from separate regions of Pf as well as the posteromedial to anterolateral topographic gradient of increasing Pf projections to Pu. An injection in the most anteromedial portion of Pf produced strong labeling in the ventral striatum. Thus, Pf transmits viscerosensory information to the "associative" and "limbic" territories of the striatum. These findings suggest the broad involvement of homeostatic afferent activity in striatal function and perhaps a role for the striatum in autonomic function.

Arterial stiffness following repeated Valsalva maneuvers and resistance exercise in young men

The purpose of this study was to compare arterial stiffness after a bout of resistance exercise (RE) and an experimental condition consisting of repeated Valsalva maneuvers (VMs). Fourteen male participants randomly completed a lower-body, unilateral RE bout and a VM bout designed to alter blood pressure (BP) in a similar pulsatile fashion. Pulse-wave velocity (PWV, measured in metres per second (m.s-1)) was used to measure central and peripheral arterial stiffness and was assessed before and 20 min after each perturbation. Beat-to-beat blood pressure (BP) was assessed during bouts using finger plethysmography. Change in systolic BP, diastolic BP, mean arterial pressure, and pulse pressure were similar during both bouts. Central PWV increased after repeated VMs (7.1 +/- 0.3 m/s to 7.8 +/- 0.3 m/s), but not after RE (7.2 +/- 0.3 m/s to 7.2 +/- 0.3 m/s) (interaction, p = 0.032). There was no change in peripheral PWV after VM (8.9 +/- 0.3 m/s to 9.3 +/- 0.3 m/s) or RE (8.5 +/- 0.2 m/s to 8.4 +/- 0.2 m/s). Arterial stiffness increased after repeated VM. Even though presented with a similar BP load, arterial stiffness did not increase after acute RE. These findings suggest a role for VM in acutely altering arterial properties.