Adding Upper Thoracic Resistance During Stationary Cycling: Physiological Effects
Adding upper thoracic (inspiratory muscle) resistance simultaneously during stationary cycling acutely reduces exercise tolerance and increases metabolic demand without providing additional cardiovascular or performance benefits compared to cycling alone. 1
Key Physiological Effects
Negative Impact on Exercise Performance
The most recent high-quality research demonstrates that combining inspiratory muscle resistance (IMR) with aerobic cycling at 30% of maximal inspiratory pressure significantly reduces time to exhaustion compared to sham conditions 1. This occurs despite no exacerbation of cardiovascular stress, suggesting the limitation is metabolic rather than cardiac.
Increased Metabolic Demand
Near-infrared spectroscopy reveals significantly greater deoxyhemoglobin concentration at peak exercise when IMR is added to cycling 1. This indicates:
- Enhanced muscle oxygen extraction
- Increased metabolic demand on working muscles
- Competing demands between respiratory and locomotor muscles
Respiratory Muscle Activation
When inspiratory muscle training devices are used during cycling, diaphragm EMG activity increases significantly beyond either activity performed alone 2. Specifically:
- Upright cycling with IMT produces greater diaphragm activation than IMT at rest
- Sternocleidomastoid activity increases with both cycling and IMT
- The combination may provide additive training stimulus to respiratory muscles
Clinical Context from Guidelines
While the ATS/ERS guidelines 3 strongly support combining upper limb resistance training with lower limb endurance exercise in pulmonary rehabilitation, this refers to training upper extremity muscles (biceps, triceps, deltoids, pectorals) - not respiratory muscles. The guidelines emphasize:
- Resistance exercise elicits reduced cardiorespiratory response compared to endurance exercise - lower oxygen consumption, minute ventilation, and dyspnea 3
- Upper limb resistance training improves upper limb strength and functional tasks (6-minute peg board test) 3
- Combination training improves outcomes without unduly increasing training time 3
Important Distinctions
The question about "upper thoracic resistance" likely refers to inspiratory muscle resistance, which differs fundamentally from upper limb resistance training:
Upper Limb Resistance (Supported by Guidelines)
- Targets skeletal muscles (arms, shoulders, chest)
- Improves functional capacity for daily activities
- Well-tolerated, especially in patients with respiratory disease
- Complements lower limb training effectively
Inspiratory Muscle Resistance (Research Evidence)
- Targets respiratory muscles (diaphragm, accessory muscles)
- Reduces exercise tolerance when combined with cycling 1
- Increases metabolic stress without performance benefit
- May activate inspiratory muscle metaboreflex, limiting blood flow to working limbs
Practical Implications
For healthy individuals seeking to maximize cycling performance: avoid adding inspiratory muscle resistance during cycling sessions. The acute effects include:
- Decreased endurance capacity
- Increased perceived effort
- Greater muscle oxygen extraction demands
- No improvement in cardiovascular parameters
If the goal is respiratory muscle training: perform it separately from cycling to avoid the competing metabolic demands that compromise both activities 1.
If the goal is comprehensive exercise training: follow guideline recommendations to combine upper limb resistance exercises (free weights, elastic bands) with cycling, which improves overall muscle strength and exercise capacity without the detrimental effects seen with inspiratory resistance 3.