Photo Credit: Spectral-Design
The following is a summary of “Effect of exercise interventions on oxygen uptake in people with chronic obstructive pulmonary disease: A network meta-analysis of randomized controlled trials,” published in Annals of Physical and Rehabilitation Medicine.
Researchers conducted a network meta-analysis (NMA) to find the most effective exercise intervention for improving maximal oxygen uptake of people with COPD.
To facilitate the study, two reviewers manually searched through six online research databases for relevant studies published any time between the inception of those databases and February 2024. Their criteria included randomized control trials related to the effect of exercise on oxygen uptake in people with COPD. The reviewers excluded studies that compared exercise with other interventions, included people with other health conditions, failed to compare different types of exercise, or lacked data to measure any improvements in maximal oxygen uptake.
The researchers grouped included studies into four categories:
- Active mind-body movement therapies: Exercise interventions that use deep and controlled breathing, flexibility, and strength in combination with daily walks.
- Endurance: Focused on increasing participants’ heart rates and energy expended. Three subcategories existed: interval training, continuous high-intensity, and continuous low-intensity.
- Strength: Training including both upper and lower body strengthening interventions.
- Combined: Interventions that used strength and endurance exercises within a single session.
The researchers performed the NMA using frequentist random effects methods. The authors presented the data using a network diagram, league table, rankogram, and the surface under the cumulative ranking (SUCRA). Then, they calculated the standard mean differences between the different types of interventions using the DerSimonian-Laird random effects methods.
The researchers identified 22 randomized control trials for inclusion in the meta-analysis, totaling 1,051 study participants. Among these studies, comparisons of maximal oxygen uptake scores were highest between continuous moderate-intensity endurance exercise and a control (ES 1.17; 95% CI, 0.59-1.74), continuous high-intensity endurance exercise and a control (ES 0.47; 95% CI, 0.08-0.85), and combined exercise and a control (ES 0.41; 95% CI, 0.18-0.64).
An analysis using a cumulative rankogram showed that continuous moderate-intensity endurance exercise had the highest probability for being the first line of treatment. The SUCRA identified it as the most likely best treatment (98%).
Researchers found that people with COPD showed the greatest improvement in oxygen uptake from engaging in continuous moderate-intensity endurance exercise. Continuous high-intensity endurance exercise and combined exercise are also effective. Exercise increases mitochondrial biogenesis, which can be evaluated by measuring the expression level of gene PGC-1α. Studies show that PGC-1α levels are highest during moderate and high-intensity endurance exercise, but higher intensity doesn’t increase PGC-1α levels more than moderate intensity.
Furthermore, the researchers found that continuous moderate-intensity endurance exercise is most effective because people with COPD have a decrease in exercise tolerance and rapid onset of muscle fatigue, which means it takes longer for them to reach the plateau of maximum oxygen consumption. As a result, they have a greater ventilatory demand.
One of the biggest limitations for this meta-analysis is that testing for VO2 peak is cost-prohibitive and inaccessible. Nine of the studies evaluated VO2 and didn’t find any significance between the type of exercise and improved oxygen uptake, but they found moderate improvements in studies that measured VO2 peak.
