Brick effect: neuromuscular control & running economy after cycling
Tier-dependent
Protocol & Participants
n=7 elite international triathletes
Muscle recruitment (EMG) and sagittal-plane joint angles of the left lower limb, plus running economy, compared between a control run (no preceding cycle) and a transition run preceded by cycling
Two cycle protocols: 20-min low-intensity and 50-min high-intensity
Key Results
Muscle recruitment and joint angles: no difference between control and transition runs for either cycle protocol
Running economy: no difference — low-intensity protocol 62.4 ± 4.5 vs 62.1 ± 4.0 ml/min/kg; high-intensity protocol 63.4 ± 3.5 vs 63.3 ± 4.3 ml/min/kg (both p > 0.05)
Authors' conclusion: neither low- nor high-intensity cycling adversely influenced neuromuscular control or running economy in elite international triathletes
Background stated in the abstract: cycling impairs running muscle recruitment and performance in SOME highly trained triathletes. The companion paper (Bonacci 2010, lesser-trained triathletes; DOI in the Journal line) is the source of the entry's "disruption in less-trained athletes" claim — its abstract was not retrieved in this pass, so that direction is not verified here
Practical Application
In 7 elite international triathletes, neither a 20-min easy nor a 50-min hard ride changed running muscle recruitment, joint kinematics or running economy (62.4 vs 62.1 and 63.4 vs 63.3 ml/min/kg, p > 0.05): at the top level the bike-to-run transition is "absorbed." The abstract itself notes that cycling does impair running recruitment in some highly trained triathletes — so a masters athlete should expect the effect and train the transition
Brick sessions (running straight off the bike) are the specific stimulus; the elite result suggests resistance to the brick effect is an adaptation, not a given. Inference, not tested: the resistance is trainable
Do not judge your running form by the first minutes after cycling until you have tested yourself — the effect is individual ("some" athletes)
Consistent with the McKay logic (REF-529): effect/adaptation depend on tier
Limitations
n=7, one elite squad; within-subject comparison, not longitudinal
The tier contrast (elite vs lesser-trained) rests on two separate studies, not one design; the lesser-trained paper's abstract was not retrieved for this check
Cycling → running only; does not cover the swim → cycling transition
How this entry was checked and changed
Why this level
regraded 2026-09-27 from B+: within-subject comparison, n=7
Content correction 2026-09-27
Added n=7, the two cycle protocols (20 min low / 50 min high intensity) and the running-economy values from the abstract
"In LESS-trained triathletes cycling DISRUPTS neuromuscular control" flagged as coming from the companion paper, whose abstract was not retrieved (the 2011 abstract says "some highly trained triathletes")
Level B+ -> B (within-subject, n=7); Tier line restated (this paper = elite only); Sport line "cycling, running, swimming" -> "cycling, running, triathlon"