Effects of Concurrent Endurance and Strength Training on Running Economy and VO2 Kinetics in Triathletes
Participants
n=15 triathletes, assigned to endurance + strength (ES) or endurance-only (E) training for 14 weeks
Protocol
Training programmes were similar in both groups except that ES performed two heavy weight training (HWT) sessions per week in addition — a concurrent design, not a sequenced one
Tests before and after: incremental field running test (VO2max, velocity at VO2max, second ventilatory threshold VT2); a 3000-m run at constant velocity set at 25% of the difference between VO2max and VT2 to measure running economy and VO2 kinetics; maximal hopping tests (maximal mechanical power, lower-limb stiffness); maximal concentric lower-limb strength
Key Findings
Maximal strength increased in ES (p<0.01) and was unchanged in E
Hopping power decreased in E (p<0.05); after training, hopping power was greater in ES than in E (p<0.001)
Running economy after training was better in ES than in E (p<0.05)
VO2max, leg hopping stiffness and VO2 kinetics (primary phase, slow component) were not significantly changed by training in either group
Authors' conclusion: additional heavy weight training improved maximal strength and running economy with no significant effect on the VO2 kinetics pattern in heavy exercise
Practical Application
In 15 triathletes over 14 weeks (Millet 2002), adding two heavy weight training sessions a week to the same endurance programme improved maximal strength and running economy versus endurance-only training, and preserved hopping power (which fell in the endurance-only group) — with no change in VO2max or in VO2 kinetics. Strength work ran concurrently with endurance training for the whole 14 weeks.
The benefit was an economy and neuromuscular one, not an aerobic-ceiling one: expect cheaper running at a given speed, not a higher VO2max.
The endurance-only group lost hopping (explosive) power over the block — endurance training alone can erode neuromuscular qualities, and two heavy sessions a week prevented that.
Nothing here supports sequencing strength "early" and cycling "late": the trial tested concurrent training and found it worked; running economy, not cycling power, was the outcome.
Not from this paper; the base's own practice: two heavy lower-body sessions a week alongside normal endurance training, kept through the block rather than front-loaded.
Limitations
Small parallel trial (n=15 in two groups); the abstract does not state randomisation or the size of the economy change.
Running outcomes in triathletes; no cycling or swimming outcome was measured.
14 weeks, single research group; VO2 kinetics unchanged may reflect low power to detect it.
Effect sizes (percent economy change) are not in the abstract, so no number can be cited from this entry.
How this entry was checked and changed
Why this level
regraded 2026-09-27 from A: parallel controlled trial, n=15 (two groups)
Content correction 2026-09-27
"+6.9% running economy", "+4-5% cycling power" -> the abstract reports economy better in ES than E (p<0.05) without a percentage, and no cycling outcome at all; both numbers removed.
"Periodic emphasis (strength weeks 1-3, cycling weeks 4-10, integration 11-14) superior to simultaneous; sequencing eliminates antagonism", the 14-week block plan (70/50/80/40/60 % splits) -> invented and contrary to the design: ES did two HWT sessions a week concurrently for all 14 weeks. Removed.
Title "Combining Cycling and Strength Training: Optimal Periodization Approach" -> the paper's title; Type "integration methodology study" -> controlled parallel trial; Level A -> B (n=15); Sport "cycling, running, triathlon" -> running, triathlon, strength. Added hopping power and VO2 kinetics results.
Full text (checked 2026-10-12)
Fifteen well-trained triathletes were randomly assigned to ES (N = 7) or E (N = 8); seven were international-level (elite national team) athletes, matched three in ES and four in E (full text).
The 14-wk winter block followed a 10-wk preconditioning phase, endurance training was mostly aerobic under 70% of VO2, and total training was 20.5 ± 3.8 h/wk in ES and 20.3 ± 3.0 h/wk in E (full text, Table 1).
ES did a lower-limb HWT session twice a week (hamstring curl, leg press, seated press, parallel squat, leg extension, heel raise): two warm-up sets, then three to five sets to failure of 3–5 reps at > 90% 1RM (full text).
The strength programme ran in 3-wk periods with three sets in the first week, four in the second and five in the third, and 1RM was reassessed every 3 wk (full text).
After training, running energy cost was lower in ES than E at 75% VVO2max (180.2 ± 20.0 vs 203.2 ± 20.2 mL·kg-1·km-1; effect size 1.14) and at Δ25% (185.4 ± 16.3 vs 205.2 ± 18.1 mL·kg-1·km-1; effect size 1.15); before training the groups did not differ (full text).
In ES, 1RM half-squat rose from 214 ± 27 to 268 ± 16 kg and 1RM heel raise from 224 ± 17 to 261 ± 21 kg, while E was unchanged (200 ± 28 to 208 ± 27 kg; 197 ± 24 to 198 ± 25 kg) (full text, Table 4).
Hopping power fell in E from 2963 ± 535 W to 2625 ± 631 W (effect size 0.58) but not in ES (3232 ± 412 W and 3410 ± 720 W), and hop height fell in E from 0.273 to 0.240 m (full text, Table 4).
Velocity at VO2max rose in ES from 19.5 ± 1.0 to 20.0 ± 0.8 km·h-1 (P < 0.01) but not in E (19.3 ± 1.0 to 19.8 ± 1.2 km·h-1); the group × time interaction was not significant (full text).