Balloon-based exercise enhances abdominal activation: a comparison between one expert and one novice with chronic low back pain

Abstract

[Purpose] While forced exhalation with balloon-blowing has been reported to facilitate abdominal muscle activity, few studies have examined its effects using imaging. We aimed to compare abdominal muscle morphology across three conditions, end-inspiration, end-forced expiration, and end-forced expiration with balloon-blowing, between a balloon-blowing exercise expert and a novice with chronic low back pain, assessed using ultrasound imaging. [Participants and Methods] A 61-year-old male expert and a 51-year-old male novice participated. The thicknesses of the transversus abdominis, internal oblique, and external oblique were measured using ultrasound imaging during end-inspiration, end-forced expiration, and end-forced expiration with balloon-blowing. The thickness and contraction ratios, calculated by dividing the thickness at end-forced expiration by that at end-inspiration, were compared within and between participants. [Results] The expert demonstrated a 1.33 mm thicker transversus abdominis and a 4.95 mm thicker internal oblique than those of the novice at end-inspiration. Balloon-blowing increased all muscle thicknesses in both participants compared with end-inspiration. The contraction ratios of the muscles during forced expiration with balloon blowing were 1.14- to 1.80-fold higher than the ratios at end-forced expiration in both participants. [Conclusion] These findings suggest the potential usefulness of balloon-blowing for activating abdominal muscles, especially in individuals with chronic low back pain.

INTRODUCTION

Abdominal breathing, commonly referred to as diaphragmatic breathing, is a technique that emphasizes the coordinated movement of the diaphragm and abdominal muscles to facilitate deeper, more efficient respiration¹⁾. This technique, often defined by equal ratios of inhalation, breath-holding, and exhalation, has been widely adopted by military personnel for stress regulation and performance enhancement¹⁾. It is associated with a range of physiological and psychological benefits, including reduced heart rate and blood pressure, decreased muscle tension, improved oxygenation, and enhanced relaxation¹⁾. As a result, this method serves as a valuable intervention not only for stress management but also for supporting individuals with various medical conditions, such as chronic obstructive pulmonary disease, gastroesophageal reflux disease, and anxiety-related disorders^{1, 2)}. In addition, this breathing strategy is closely linked to spinal stability, as the diaphragm acts as the superior component of the core’s muscular cylinder. When functioning synergistically with the transverse abdominis (TrA), multifidus, and pelvic floor muscles, the diaphragm helps regulate intra-abdominal pressure, supports lumbopelvic stability, and enhances respiratory efficiency^{3, 4)}. A well-coordinated abdominal breathing technique is widely recognized as a fundamental element in maintaining core stability and spinal support^{3, 5)}. Specifically, by promoting proper engagement of the diaphragm and deep abdominal musculature, this breathing strategy regulates intra-abdominal pressure, provides lumbopelvic stability, and contributes to efficient postural control during both static and dynamic activities^{3, 5)}.

Despite its benefits, engaging the abdominal muscles during breathing can be particularly difficult for individuals with underlying conditions. For instance, those with breathing pattern disorders or chronic pain often develop maladaptive or paradoxical breathing patterns—such as inward abdominal movement during inhalation—that interfere with proper diaphragmatic activation⁶⁾. Research also suggests that individuals with anxiety or musculoskeletal disorders frequently struggle to voluntarily control or engage their abdominal muscles during deep breathing⁷⁾. These challenges often necessitate prolonged training and therapeutic guidance. As such, individualized rehabilitation strategies and neuromuscular re-education are essential to restoring effective abdominal muscle function and optimizing breathing mechanics in affected populations.

An increasingly popular and innovative approach involves incorporating balloon blowing into breathing exercises to enhance respiratory control, core stability, and lung expansion during physical activity⁸⁾. During forceful exhalation, such as that required in balloon-blowing tasks, the primary expiratory muscles engaged include the abdominal wall muscles—TrA, internal oblique (IO), and external oblique (EO). This technique may be especially beneficial for individuals who struggle to activate their abdominal muscles, as exhaling through the balloon provides resistance that encourages engagement of the abdominal muscles^{8, 9)}.

While it is commonly believed that balloon-blowing facilitates activation of the abdominal muscles, especially TrA, current evidence supporting this claim remains limited. Ultrasound imaging is a reliable and sensitive method for assessing the morphology and function of abdominal muscles during breathing, offering high reproducibility, minimal inter- and intra-rater variability, and the ability to detect clinically meaningful changes¹⁰⁾. Therefore, the purpose of this case study was to examine differences in abdominal muscle thickness during three phases of breathing—end-inspiration, end-forced expiration, and end-forced expiration with balloon-blowing—between two distinct individuals: a trained instructor experienced in the balloon breathing exercise program, and a novice with chronic low back pain (LBP) who has limited experience in performing abdominal breathing.

PARTICIPANTS AND METHODS

The study employed a comparative case study design with repeated measures to examine abdominal muscle activation under different breathing conditions. Two male participants were recruited using purposeful sampling to represent distinct levels of expertise in abdominal breathing¹¹⁾. This case study did not undergo formal institutional review board approval due to its exploratory, observational nature and very small sample size. Both participants provided informed consent and were made aware that participation was voluntary, with the option to withdraw at any time. Furthermore, all procedures were non-invasive and posed minimal risk.

The expert participant was a 61-year-old male instructor (height: 1.83 m, weight: 79 kg) with two years of consistent experience in a structured balloon breathing exercise program, practicing for 20–30 minutes daily. He also serves as a professional instructor for an “Ab Lab” class at a local gym, where he incorporates balloon-based breathing techniques into exercises. The novice participant was a 51-year-old male (height: 1.89 m, weight: 72 kg) with a history of chronic LBP lasting over 10 years. He works as an independent contractor specializing in information technology services and home improvement projects. The participant reported no prior experience or knowledge of abdominal or diaphragmatic breathing techniques.

As part of the expert participant’s daily exercise routine, he regularly engaged in a progressive series of breathing and core stabilization exercises designed to enhance respiratory control and abdominal muscle activation. The session began with diaphragmatic breathing in standing, first without and then with balloon exhalation. The routine progressed to supine exercises with legs supported on a chair, incorporating a yoga block between the knees to engage the adductors and pelvic floor. Advanced variations were performed in a hooklying position without external support, further challenging core control. Dynamic tasks were then introduced, including dead bugs and side-lying leg lifts (both lying flat and on the forearm), targeting coordination and lateral stability. More advanced movements included scissors, criss-cross, and bicycle leg motions, all synchronized with balloon exhalation. The routine concluded with upright exercises such as single-leg lunges and Bulgarian split squats, integrating breath control with functional strength and oblique activation. The novice participant’s regular physical activity consisted of moderate aerobic exercise, primarily brisk walking, for 45–60 minutes per day.

A trained physical therapist performed the ultrasound imaging acquisition using a portable ultrasound imaging scanner (GE LOGIQ-e, GE Healthcare, Milwaukee, WI, USA), in brightness mode. The imaging parameters were set to a gain of 55, a depth of 60 mm, and a frequency of 10.0 MHz. To standardize image acquisition, the transducer was placed 1 inch superior and medial to the left iliac crest, with efforts made to maintain the same transducer position throughout the measurements¹²⁾. Ultrasound images were acquired under three breathing conditions: end-inspiration, end-forced expiration, and end-forced expiration with balloon-blowing in a supine position with the hip and knee flexed 90° (Fig. 1). During inspiration, participants were instructed to take a deep breath in. For end-forced expiration, they were asked to exhale as much air as possible, while in the balloon-blowing condition, they exhaled forcefully into a balloon. At the end of inspiration and both expiration phases, participants were asked to hold their breath to allow for data collection. The end-inspiration was used to capture the thinnest thickness of the abdominal muscles, which is often defined as the resting muscle thickness¹³⁾. The two end-forced expiration conditions were used to capture the muscle thickness during contractions of the abdominal muscles. Specifically, the end-expiration phase represents submaximal contraction, while the forced-expiration phase reflects maximal contraction¹⁴⁾. For each condition, three images were acquired.

Fig. 1.

Ultrasound imaging acquisition of abdominal muscles during forced expiration with balloon-blowing in the expert participant.

All ultrasound images were analyzed using ImageJ software (available from https://imagej.nih.gov/ij/). The thickness of the TrA was measured as the distance between the inner edges of the fascia layers at 25 mm lateral to the muscle–fascia junction of the TrA¹²⁾. The thicknesses of the IO and EO were also measured as the distance between the inner edges of the fascia layers along the same reference line used for the TrA (Fig. 2). For each condition, muscle thickness was calculated as the mean of three images and used for comparison. Contraction ratios for end-forced expiration and end-forced expiration with balloon-blowing were calculated by dividing the thickness in each condition by the resting thickness measured at end-inspiration.

Fig. 2.

Abdominal muscle ultrasound measurements during end-inspiration, end-forced expiration, and end-forced expiration with balloon-blowing for both participants. TrA: transversus abdominis; IO: internal oblique; EO: external oblique.

RESULTS

At end-inspiration, although the expert’s EO was 0.68 mm thinner than that of the novice, the TrA and IO were 1.33 mm and 4.95 mm thicker, respectively. During forced-expiration with balloon-blowing compared with end-inspiration, while the novice showed increases of 1.09 mm, 3.85 mm, and 4.50 mm in the TrA, IO, and EO, respectively, the expert demonstrated larger increases of 5.65 mm, 9.52 mm, and 2.16 mm in the TrA, IO, and EO. At end–forced expiration relative to end-inspiration, the novice demonstrated small decreases in muscle thickness (approximately 0.2–0.5 mm) across the TrA, IO, and EO. In contrast, the expert exhibited increases in muscle thickness, with the TrA, IO, and EO increasing by 6.61 mm, 3.30 mm, and 1.34 mm, respectively (Table 1).

Table 1. Comparisons of muscle thicknesses and contraction ratios between the two participants.

Muscles	Conditions	Muscle thickness (mm)		Contraction ratio
		Expert	Novice	Expert	Novice
Transversus abdominis	End-inspiration	4.30	2.97
	End-forced expiration	10.91	2.79	2.68	0.94
	End-forced expiration with balloon-blowing	9.95	4.06	2.42	1.40
Internal oblique	End-inspiration	14.46	9.51
	End-forced expiration	17.76	8.97	1.23	0.94
	End-forced expiration with balloon-blowing	23.98	13.36	1.67	1.40
External oblique	End-inspiration	6.06	6.74
	End-forced expiration	7.40	6.28	1.32	0.93
	End-forced expiration with balloon-blowing	8.22	11.24	1.50	1.67

Both individuals demonstrated a 14% to 80% increase in contraction ratios during forced expiration with balloon-blowing compared to end-forced expiration, except for the TrA in the expert, which showed a reduction. Specifically, the novice exhibited a 49% increase in the contraction ratios of the TrA and IO, and an 80% increase in that of the EO, during end-forced expiration with balloon-blowing compared with end-forced expiration. These values exceeded those of the expert, who demonstrated a 10% decrease in the TrA and increases of 36% in the IO and 14% in the EO contraction ratios when comparing balloon-blowing during forced expiration to end-forced expiration alone (Table 1).

DISCUSSION

Spinal stability provided by the abdominal wall muscles is essential for managing LBP. Although balloon-blowing exercises are used to facilitate abdominal wall activation, imaging-based outcome measures have remained limited. To the best of our knowledge, this is the first study to quantify abdominal wall activation across respiratory conditions—including end-forced expiration with balloon-blowing—using ultrasound imaging. Muscle thickness and contraction ratios for the TrA, IO, and EO were compared between the expert and novice, and within the participants. The study findings suggested that balloon-blowing exercises may enhance abdominal muscle activation, especially in individuals with LBP. The novice showed minimal activation during normal forced expiration but improved significantly with balloon-blowing. This indicates enhanced recruitment of the abdominal musculature when exhalation resistance is introduced.

Another key finding of our study was that the expert demonstrated 1.5 to 4.0 times thicker TrA and IO muscle thickness than the novice with chronic LBP across all conditions. The novice demonstrated TrA, IO, and EO thicknesses at end-inspiration that were comparable to those previously reported in individuals with LBP, with values ranging from 3.1–4.1 mm, 7.2–9.0 mm, and 5.9–6.2 mm for the TrA, IO, and EO, respectively^{3, 15, 16)}. In contrast, the expert’s TrA and EO thicknesses at end-inspiration were comparable to, or greater than, previously reported values in individuals without LBP (TrA: 3.3–3.8 mm; EO: 5.0–6.5 mm). However, his IO thickness was nearly double the values reported in prior studies^{3, 15, 16)}. This may suggest that the expert possesses greater generalized abdominal muscle thickness compared to individuals both with and without LBP. Notably, the expert reported a two-year history of regular balloon-blowing exercises. The resistance generated by the balloon has been shown to require increased activation of the muscles involved in forced expiration¹⁷⁾. Collectively, these findings point to the potential long-term effects of balloon-blowing practice on abdominal muscle thickness.

The expert demonstrated higher contraction ratios for all muscles than the novice at end-forced expiration. The expert’s ratios were also similar to or greater than those previously reported in individuals without LBP, with reported ranges of 1.09–1.91 for the TrA, 1.06–1.56 for the IO, and 0.95–1.10 for the EO, respectively^{3, 15, 16)}. Additionally, in the novice, balloon-blowing produced higher contraction ratios than at end-forced expiration. End-forced expiration contraction ratios have been reported to range from 1.07 to 2.23 for the TrA, 1.06 to 1.17 for IO, and 0.95 to 1.05 for EO in individuals with chronic LBP^{3, 15, 16)}. Importantly, while the novice demonstrated lower ratios at end-forced expiration (0.94 for the TrA and IO, and 0.95 for the EO), his balloon-blowing ratios ranged from 1.40 to 1.67, exceeding previously reported end-forced expiration values in individuals with chronic LBP. This is significant given that individuals with chronic LBP often experience difficulty activating the abdominal wall muscles¹⁸⁾. These findings suggest that balloon-blowing may help facilitate activation of abdominal muscles that are otherwise difficult to recruit.

The primary limitation of this study is the small sample size, as our goal was to purposefully explore potential differences in abdominal muscle thickness between two distinct individuals: a trained instructor experienced in the balloon breathing exercise program and a novice with chronic LBP who had limited experience with abdominal breathing. While participants’ differing backgrounds may have amplified the observed effects of balloon-blowing, they also introduce potential selection bias. Additionally, the highest contraction ratio of the EO observed in the novice may reflect a relatively challenging balloon resistance. For spinal stability under low force demands, activation of the TrA and IO is sufficient, whereas EO activity increases as abdominal task demands increase¹⁹⁾. Therefore, future studies with larger samples, more rigorous recruitment strategies, and tailored balloon resistance are needed to reduce this bias and allow for appropriate statistical analyses of the effects of balloon-blowing exercises on abdominal muscles.

In summary, this study suggests that balloon-blowing exercises may be effective in activating the abdominal muscles, including the TrA, IO, and EO. Both participants demonstrated increased abdominal muscle thickness during balloon-blowing. However, all muscles of the individual with chronic LBP showed greater contraction ratios during the balloon-blowing condition—defined as the change in muscle thickness during expiration relative to inspiration—than during the condition without balloon-blowing. These findings indicate that balloon-blowing may be beneficial for enhancing abdominal muscle activation, especially in persons with chronic LBP. Future larger scale studies are needed to examine the long-term effects of balloon-based training programs on the morphology of the abdominal muscles.

Funding and Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as potential competing interests.