Physiological Differences Between Cycling and Running
Lessons from Triathletes
Key Findings (abstract)
VO2max is specific to the exercise modality: most studies find runners reach a higher VO2max on the treadmill, whereas cyclists reach a VO2max on the cycle ergometer similar to their treadmill value; in triathletes there is generally no difference between the two
Muscles adapt specifically to the trained task: submaximal variables such as the ventilatory threshold improve, in some cases without a change in VO2max — an effect probably larger in cycling than in running. Skill (motor-unit recruitment patterns) influences the anaerobic threshold in cycling
Training transfer is asymmetric: it is likely that more physiological transfer occurs from running to cycling than vice versa
In triathletes, data on the anaerobic threshold in cycling vs running are conflicting — probably a mix of actual training load and prior training history in each discipline
Other differences: heart rate differs between the two activities at both maximal and submaximal intensities; delta efficiency is higher in running; ventilation is more impaired in cycling; pedalling cadence affects the metabolic response during cycling AND during a subsequent running bout (the optimal cadence is still debated); central fatigue and the loss of maximal strength after prolonged exercise are greater in running than in cycling
Mechanisms behind the VO2max and threshold differences are "not largely understood" — probably the relative adaptation of cardiac output (VO2max) and the recruited muscle mass with its oxidative capacity (threshold)
Practical Application
Review of cycling-vs-running physiology in triathletes, runners and cyclists: VO2max is modality-specific (runners test higher running; cyclists similar in both modes; triathletes no difference), threshold adaptations are specific to the trained mode, and transfer is likely greater from running to cycling than the reverse — a masters athlete combining the two should not expect cycling fitness to equal running fitness; running-specific work is needed
Heart rate differs between modalities at maximal and submaximal intensities — set HR zones per sport, do not copy cycling zones to running. Inference, not tested: the abstract states the difference, not the zone rule
Cycling cadence before a run changes the metabolic response of that run — a lever for the bike-to-run transition; the optimal cadence is still debated (see REF-539 for elite transition data)
Cross-training cycling↔running supports the aerobic base; the review's asymmetry (running → cycling transfers more) means a runner adding cycling keeps more than a cyclist adding running. Inference, not tested: if you must choose one "specific" mode, make it running
Limitations
2009 narrative review; many findings come from non-elite subjects, and the authors call the underlying mechanisms "not largely understood"
No numbers in the abstract; the size of the VO2max gap between modes is not reported here
Principles are stable; newer durability data add nuance
How this entry was checked and changed
Why this level
regraded 2026-09-27 from A: narrative review without systematic method (leading triathlon-physiology group)
Content correction 2026-09-27
"VO2max in running is usually ~5-7% higher than in cycling" -> number not in the abstract; removed. Abstract: runners higher on treadmill, cyclists similar in both modes, triathletes no difference
"Brick: prior cycling disrupts running economy for the first 5-10 min" -> not in this abstract; removed (abstract: pedalling cadence affects the metabolic response of a subsequent run)
"Cycling and running economy correlate weakly" -> not in the abstract; replaced with the abstract's statements (delta efficiency higher in running; asymmetric transfer running → cycling; HR differs between modes)
Level A -> B+ (narrative review); Sport line "cycling, running, swimming" -> "cycling, running, triathlon"
Full text (checked 2026-10-12)
Bouckaert et al. reported VO2max 14% higher in treadmill running than bicycle ergometry in runners, and 11% higher on the bicycle ergometer than the treadmill in cyclists (full text).
O'Toole et al. found no significant differences in cycling and running VO2max in male (68.8 ± 10.4 vs 66.7 ± 10.1 mL/kg/min) or female (65.9 ± 8.1 vs 61.6 ± 7.0 mL/kg/min) triathletes (full text).
In triathletes, HRmax in cycling is often lower by 6–10 beats/min than in running, although other studies find HRmax similar between modes (full text).
In highly trained triathletes, HR at the VT was 145.0 ± 9.0 in cycling vs 156.0 ± 8.0 in running (80.9 ± 3.4 vs 85.4 ± 4.1% HRmax), and in elite female triathletes 164.7 ± 4.0 in running vs 148.2 ± 3.4 in cycling (full text).
Roecker et al. found a 20 beats/min difference in HR at the LT between cycle ergometer (149.9 ± 18.0 beats/min) and treadmill (169.6 ± 15.7 beats/min) (full text).
Bijker et al. found delta efficiency lower in cycling (25.7 ± 1.3%) than in running (45.5%) (full text).
Oxygen consumption in a 15-minute run after cycling rose versus an isolated run only after 90 rpm (+4.1%) and 81 rpm (+3.6%) cadences, not after 75 rpm; in another study FCC +20% in a 30-minute time trial made the subsequent 3 km run 1 minute faster than FCC -20% (full text).
After 2 hours of cycling, strength fell 13% without a central fatigue contribution, whereas an activation deficit (central fatigue) was shown after prolonged running (full text).