REF-201 · Kordi et al., 2019 · European Journal of Sport Science, · Paper

Influence of Upright Versus Time Trial Cycling Position on Determination of Critical Power and W' in Trained Cyclists

Blimited evidenceMeasured on trained to highly trained athletesWritten before October 2026, being re-checked

Kordi et al. compared mechanical power output in two riding positions and the resulting estimates of critical power (CP) and W'. Seven trained cyclists (n=7) completed three peak-power efforts and three fixed-duration trials (3, 5 and 12 min) with hands on the brake-lever hoods (BLH, upright) and in a time-trial position (TTP).

Mean power in the 5-min trial differed significantly between positions, producing a significantly lower CP estimate — but no different W' — in the TT position. TTP lowered performance in every trial, and the percentage gap between BLH and TTP grew with trial duration.

Cadence and heart rate did not differ in the 3-min trial; in the 12-min trial TTP showed a significant fall in cadence and a significant rise in heart rate. Conclusion: position affects power output and the consequent CP value, so cyclists and coaches should consider the position used when calculating CP.

Participants

n=7 trained cyclists

Key Results (from the abstract)

CP: significantly lower when estimated from TT-position trials than from upright (hoods) trials
W': not significantly different between positions
5-min trial: mean power significantly lower in TTP
Every trial: lower performance in TTP, with the BLH-TTP percentage difference increasing with trial duration (3 → 5 → 12 min)
3-min trial: no difference in cadence or heart rate; 12-min trial: significantly lower cadence and significantly higher heart rate in TTP
The abstract reports no watt or percentage values for the CP difference.

Practical Application

In 7 trained cyclists, riding the 3-, 5- and 12-min efforts in a time-trial position instead of on the hoods lowered power in every trial — more so the longer the effort — and gave a significantly lower critical power estimate with no change in W'; in the 12-min TT-position trial cadence fell and heart rate rose (within-subject study, Kordi 2019).
Run the CP test in the position the event is ridden in: a CP number without a position attached is not comparable to one measured differently, and the penalty of the aero position grows with duration, so a short test understates it.
For events ridden predominantly upright (climbing, hoods and drops), test upright; for a time trial, test on the TT bars. Do not carry one set of numbers to the other position.
The higher heart rate at a lower power in the long TT-position trial means HR-based zones also shift with position — a TT-position HR ceiling set from an upright test will be reached at lower watts.
Inference, not tested here: the usual explanations — restricted breathing mechanics, hip angle and muscle recruitment in the closed aero position — were not measured in this study. Individual differences are likely, so measure the athlete's own position effect rather than applying a fixed correction. For the separate indoor-vs-outdoor gap see REF-182.

Limitations

From the design as the abstract reports it: a within-subject comparison in seven trained cyclists — a small sample; sex and performance level are not given in the abstract.
CP and W' were estimated from three fixed-duration trials (3, 5 and 12 min) in each position; the abstract reports no watt or percentage values for the differences.
The outcomes are test estimates (CP, W') and trial power, not race performance.
How this entry was checked and changed
Why this level

regraded 2026-09-27 from B+: within-subject design with n=7

Content correction 2026-09-27
"W' may be higher in TT (compensatory effect)" -> abstract: W' not significantly different between positions.
"Difference clinically significant (>5 W)" and "indoor CP ≈ outdoor upright CP − 5-10 W" deleted: the abstract gives no watt figures.
Mechanisms (compressed diaphragm, vena cava compression, hip angle) relabelled as inference, not measured. Added the abstract's protocol (n=7; 3-, 5-, 12-min trials), the duration-dependent penalty and the 12-min cadence/HR findings.
Level B+ -> B (within-subject, n=7); Sport "cycling, swimming" -> cycling.
Cross-references to duplicate stubs repointed to their canonical entries (REF-200->REF-024); the stubs were emptied on 2026-09-27.
2026-09-28: added Limitations from the abstract (Europe PMC PMID 30009673).