The Science of Breathing During Exercise and Strength Training

In the gym, on a run, or during a demanding conditioning session, breathing can either support performance or quietly undermine it. Good breathing mechanics improve stability, efficiency and endurance. Poor breathing, on the other hand, can reduce force production, elevate blood pressure unnecessarily, compromise technique and increase injury risk.

Like most aspects of training, effective breathing is context dependent.

Breathing During Cardiovascular Exercise

During aerobic exercise such as running, rowing, cycling or swimming, the primary goal of breathing is oxygen delivery and carbon dioxide removal.

Efficient breathing helps maintain rhythm, delay fatigue and regulate exercise intensity. Research consistently shows that controlled diaphragmatic breathing improves ventilatory efficiency and exercise economy during endurance activities. (pubmed.ncbi.nlm.nih.gov)

Many recreational exercisers fall into shallow chest breathing when intensity rises. This often leads to:

• elevated heart rate,

• earlier fatigue,

• increased tension through the neck and shoulders,

• inefficient oxygen exchange.

Good endurance breathing should primarily come from the diaphragm, the large muscle beneath the lungs, rather than excessive upper chest movement.

For lower-intensity cardiovascular exercise, nasal breathing may also help regulate breathing rate and improve tolerance to carbon dioxide build-up. However, as intensity increases, most people naturally transition to combined nasal and mouth breathing to meet oxygen demand. (pubmed.ncbi.nlm.nih.gov)

Simple rhythm-based breathing patterns can also improve efficiency. Runners, for example, often benefit from syncing breathing with stride patterns to reduce unnecessary muscular tension.

Breathing During Strength Training

Strength training breathing serves a different purpose entirely.

In resistance exercise, breathing is not just about oxygen delivery, it is also about spinal stability and force transfer.

When lifting weights, controlled intra-abdominal pressure helps stabilise the spine and improve force production. This is why most coaches teach:

• inhale during the lowering phase,

• exhale during the lifting phase.

For example:

• inhale as you lower into a squat,

• exhale as you stand up.

Research shows that appropriate bracing and breathing mechanics improve trunk stiffness and spinal stability during loaded movements. (pubmed.ncbi.nlm.nih.gov)

Poor breathing during strength work commonly leads to:

• loss of spinal positioning,

• reduced lifting efficiency,

• increased lumbar stress,

• dizziness or light-headedness,

• elevated blood pressure spikes.

Many people unknowingly hold their breath during difficult repetitions without proper bracing strategy. In some cases this simply reduces exercise quality. In others, particularly in people with cardiovascular conditions or uncontrolled hypertension, it may increase risk.

When Holding Your Breath Can Actually Help

This is where nuance matters.

Advanced strength athletes often intentionally use a modified breath hold technique known as the Valsalva manoeuvre during heavy lifts such as squats, deadlifts and presses.

The Valsalva manoeuvre involves taking a deep breath and briefly holding it while bracing the abdominal wall. This significantly increases trunk stability and may improve force production during maximal or near-maximal lifts. (pubmed.ncbi.nlm.nih.gov)

Used correctly, this can enhance lifting performance and reduce spinal shear forces.

However, risks increase when:

• loads exceed technical competence,

• individuals have uncontrolled blood pressure issues,

• breathing is held excessively long,

• lifters fail to re-establish breathing between repetitions.

For most general population clients, prolonged breath holding is unnecessary. Controlled bracing combined with steady breathing is usually both safer and more effective.

In experienced lifters performing maximal efforts, the goal should not be avoiding breath holding entirely; it should be using it deliberately, briefly and with proper technique.

The Bigger Picture

Breathing is often treated as an afterthought in training, yet it underpins nearly every movement we perform.

Good breathing mechanics improve:

• endurance,

• lifting efficiency,

• trunk stability,

• recovery,

• movement quality.

Poor breathing mechanics increase unnecessary tension, reduce exercise efficiency and may elevate injury risk over time.

As with most things in fitness, the fundamentals matter.

Before chasing advanced programmes, heavier weights or harder conditioning sessions, it is worth asking a simple question:

Are you actually breathing properly while you train?

Peer-Reviewed References

• McConnell AK & Romer LM. Respiratory Muscle Training in Healthy Humans: Resolving the Controversy. International Journal of Sports Medicine, 2004. (pubmed.ncbi.nlm.nih.gov)

• Hagins M et al. Effects of Diaphragmatic Breathing on Exercise Performance. Journal of Alternative and Complementary Medicine, 2014. (pubmed.ncbi.nlm.nih.gov)

• Morton AR et al. Comparison of Maximal Oxygen Consumption with Oral and Nasal Breathing. Australian Journal of Science and Medicine in Sport, 1995. (pubmed.ncbi.nlm.nih.gov)

• Hodges PW et al. Role of the Postural Muscles of the Trunk in Breathing. Exercise and Sport Sciences Reviews, 2001. (pubmed.ncbi.nlm.nih.gov)

• Hackett DA & Chow CM. The Valsalva Maneuver: Its Effect on Intra-Abdominal Pressure and Safety Issues During Resistance Exercise. Journal of Strength and Conditioning Research, 2013. (pubmed.ncbi.nlm.nih.gov)

• MacDougall JD et al. Blood Pressure Response to Heavy Resistance Exercise. Journal of Applied Physiology, 1985. (pubmed.ncbi.nlm.nih.gov)

• Lamberg EM & Hagins M. Breathing Patterns and Trunk Stabilization. Journal of Bodywork and Movement Therapies, 2010. (pubmed.ncbi.nlm.nih.gov)