Both eccentric and concentric cycling training improved walking functional capacity after severe COVID-19, with no significant difference between groups.
Key Findings
Results
Intergroup analysis showed no significant differences between eccentric and concentric training for any outcome variable.
The median difference in 6MWT distance between ECC and CON groups was -10 m (95% CI: -42 to 22)
60 participants were enrolled; 56 were included in the modified intention-to-treat (mITT) population
44 participants completed the full 8-week program
No significant between-group differences were found for any primary or secondary outcome
The study was a multicenter, randomized, controlled, open-label trial conducted across 3 centers
Results
Both eccentric and concentric training groups showed significant within-group improvements in 6-minute walk test (6MWT) distance from baseline to 2 months.
Within-group analysis was significant for both groups: P = 0.002 for ECC and P = 0.001 for CON on mITT analysis
Per-protocol analysis also showed significance: P = 0.001 for both ECC and CON groups
6MWT improved by 18 m (IQR: 0; 72) in the ECC group and 28 m (IQR: 0; 53) in the CON group
Participants were adults under 80 years, enrolled at least 1 month after hospital discharge for severe COVID-19
Median age of the mITT population was 54.5 years (IQR: 48; 62); 59% were men
Background
Eccentric cycling was proposed as a potentially relevant rehabilitation strategy because it offers high mechanical load with low metabolic cost.
Severe COVID-19 infection leads to profound pulmonary, cardiovascular, and neuromuscular impairments
These impairments result in marked exercise deconditioning and reduced functional walking capacity after hospital discharge
Eccentric cycling was hypothesized to be advantageous due to its high mechanical load with low metabolic cost
The rationale was that this profile may benefit deconditioned post-COVID patients who may not tolerate high metabolic demands
Methods
The rehabilitation intervention consisted of 8 weeks of either eccentric or concentric ergometer training at a frequency of 3 sessions of 30 minutes per week.
Participants were randomized 1:1 to ECC or CON ergometer training
Each session lasted 30 minutes, with 3 sessions per week over 8 weeks
The primary outcome was change in 6MWT distance between baseline and post-intervention (M2)
Secondary outcomes included physical performance, muscle strength (handgrip), fatigue, and quality of life
Analyses were conducted in the mITT population using mixed models
Conclusions
The authors concluded that further randomized controlled trials are needed to confirm the effectiveness of these rehabilitation approaches for COVID-19 survivors.
Both training modalities improved walking distance, but neither was superior
The trial did not establish a definitive advantage of eccentric over concentric training
Authors called for additional RCTs to confirm findings in post-COVID populations
The trial was registered under NCT04649086
What This Means
This research suggests that structured cycling exercise—whether using a standard (concentric) or a specialized downhill-style (eccentric) bike—can help people recovering from severe COVID-19 walk farther after just 8 weeks of training. Both groups in this study, which included 56 adults who had been hospitalized for severe COVID-19, improved their scores on a standard walking test used to measure physical fitness and endurance. The improvements were statistically meaningful within each group, though modest in absolute terms (about 18–28 meters on average in the 6-minute walk test).
However, the study found no meaningful difference between the two types of cycling training. Eccentric cycling had been proposed as potentially more suitable for people who are very deconditioned after illness, because it places high mechanical stress on muscles while requiring less cardiovascular effort—potentially allowing weaker patients to build strength without overtaxing their heart and lungs. Despite this theoretical advantage, the outcomes for eccentric and concentric training were statistically equivalent across all measures, including muscle strength, fatigue, and quality of life.
This research matters because many COVID-19 survivors—particularly those who were hospitalized—continue to experience reduced physical capacity and exercise tolerance long after their acute illness. It suggests that a structured, supervised cycling program of either type may be a practical rehabilitation tool to help restore walking ability, but it remains uncertain which approach is best. The authors note that larger and longer studies are needed before firm recommendations can be made.
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Cormier C, Lanhers C, Rannou F, Grolier M, Pelletier Visa M, Féasson L, et al.. (2026). Impact of eccentric exercise on walking functional capacity after severe COVID-19: randomized, controlled open-label trial.. Annals of physical and rehabilitation medicine. https://doi.org/10.1016/j.rehab.2026.102125