REF-1546 · Christensen & Bangsbo, 2016 · Frontiers in Physiology · Paper · PubMed · Free full text

Does a first 4-min maximal effort cost the second the same day?

World-class pursuit finals were about 1% slower than qualifying. In the lab peak oxygen uptake and economy showed no clear change 3 h later; power loss was not tested.

Main caveat: The two parts have different riders, gaps and tasks. World-class men, ~6.5 h, real races; trained road cyclists, 3 h, an ergometer.
limited evidenceMeasured on trained to highly trained athletes

Part A extracted qualifying and final times for the four finalists at the men's 4000-m individual pursuit, World Championships 2008-2015, on the same day, on average 6:28 ± 1:50 h:min apart. Times were 4:18.7 ± 2.6 min:s in qualifying and 4:21.1 ± 3.2 in the final, about 1% slower, in all four qualifying positions.

In Part B, twelve trained road cyclists rode an identical warm-up and a ~4-min effort, then a second warm-up and an open 4-min performance test 3 h later, on two days: control and with 15 min of cold water (about 15°C).

Peak oxygen uptake (5.04 ± 0.50 and 5.00 ± 0.49 L/min) and peak lactate (13 ± 3 and 14 ± 3 mmol/L) showed no main effect between the first and second effort; economy was not impaired; potassium rose less in the second warm-up. Cold water made no clear difference to power (406 ± 43 against 405 ± 38 W, P = 0.66), though the first 30 s was harder after it.

Our reading: real championship data show a small slowing, and in the lab peak oxygen uptake, lactate and economy held; the lab does not show that output held, because it could not. What this isolates is a repeated effort with food between, with no comparison to a day without the first effort.

Protocol

Design, Part A: official timekeeper data for the four finalists; 2007 dropped because the final was stopped early, no data before that. Two-way repeated-measures ANOVA for position and race.
Design, Part B: crossover with half starting on each condition; randomisation is not stated; trials 6 ± 3 days apart; no training the day before.
First effort: a 15-min warm-up (9 min at 213 ± 23 W, 3 min at 255 ± 28 W, 3 min at 304 ± 32 W), then a partly paced effort: 95% of the familiarisation mean power for the first 3.5 min, then finishing a fixed target of work as fast as possible. Time 4:06 ± 0:06 and 4:07 ± 0:05 min:s; mean power 398 ± 36 and 398 ± 39 W.
Recovery: 3 min at 30 W; on the cold-water day 15 min immersed to the navel at 14.9°C within 5 min; within 20 min of the effort 1 g/kg carbohydrate and 0.2 g/kg protein as chocolate milk and soda; second warm-up from 2 h 35 min.
Second effort: an open 4-min test on a mechanically braked ergometer at a fixed gear, 3 h after the end of the first, with no verbal support.
Measures: oxygen uptake at 30-s highest value, gross efficiency in the last minute of the 9-min warm-up block, venous lactate and potassium, a 1-10 readiness score.
Funding and interests: supported by Team Danmark; the authors declare no commercial or financial conflict.

Key Results

MeasureFirstSecondP
World Championship 4000-m time, finalists (min:s)4:18.7 ± 2.64:21.1 ± 3.2< 0.001
Lab peak oxygen uptake (L/min)5.04 ± 0.505.00 ± 0.49no main effect
Lab peak blood lactate (mmol/L)13 ± 314 ± 30.16 (race type)
Gross efficiency, control (%)19.4 ± 1.119.6 ± 1.30.31 (warm-up)
Gross efficiency, cold water (%)19.3 ± 1.119.5 ± 1.50.31 (warm-up)
Second-effort measureControlCold waterP
Mean power, 4-min test (W)405 ± 38406 ± 430.66
Mean power, first 30 s (W)425 ± 63435 ± 64< 0.05; pacing × recovery 0.005
Readiness (1-10)7 ± 17 ± 1no difference
Lactate before the test (mmol/L)2.6 ± 0.82.7 ± 0.9no difference
Our arithmetic: 2.4 s slower from the printed means; the authors' own discussion says about 2.5 s, and the abstract prints 259 ± 3 and 261 ± 3 s.
Do not compare 398 W with 405 W as a recovery. The first effort was paced to a set work and the second was open, so the higher mean of the second is a design choice, not a sign of improvement. The authors themselves ask for two identical tests 3-6 h apart.
Slipstream was checked. Riders with 5 s or less benefit against their qualifying rival (n = 13) rode 4:17.8 and 4:20.1; the rest 4:19.3 and 4:21.2, both P < 0.001.
Potassium: the rise over the warm-up was smaller the second time (main effect P = 0.001), in both conditions.
No clear difference, not "the same." The authors' discussion uses "the same"; no equivalence test was run.

Mechanisms

Measured: peak oxygen uptake, lactate, gross efficiency and potassium showed no impairment 3 h after one ~4-min effort.
Authors' interpretation: cardiovascular delivery seems intact, so the race slowing lies elsewhere. One candidate they name is low glycogen acting on calcium handling, from a calculation of about 450 mmol of net use, not a measurement; they also name inflammation, pressure and tactics.
Authors' interpretation: faster opening after cold water with no change in readiness is compatible with placebo, or with a readiness score too coarse to see a real change.
Not measured: muscle glycogen, reactive oxygen species, track power, food between the championship races, muscle biopsies. No training response.

Practical Application

Does a first 4-min maximal effort cost the second the same day? World-class pursuit finals were about 1% slower than qualifying. In the lab peak oxygen uptake and economy showed no clear change 3 h later; power loss was not tested.
Good for: expecting a small slowing in a same-day race double at the top end of a ~4-min event, about 1% with a gap of about 6.5 h, in men. Tactics in a final could explain part of it, and so could selection: finalists are the fastest qualifiers, so some slowing is expected anyway (our inference).
Good for: saying that oxygen uptake alone does not tell you a second maximal effort is fully back. Peak oxygen uptake held in one group while race times fell in another, though in different riders and at different gaps, so this is our inference.
Good for: not counting on 15 min of cold water between two ~4-min efforts for more power. No clear benefit in 12 riders, with a harder opening 30 s.
Not good for: claiming that training quality holds on a double day. These are single maximal efforts, not interval sets, with no fatigue across a block.
Not good for: the size of second-effort power loss. The lab cannot give it; the race data have no power.
Not good for: recovery food advice. A single dose was given to all (1 g/kg carbohydrate, 0.2 g/kg protein); food was not compared.

Limitations

The two parts have different riders, gaps and tasks. World-class men, ~6.5 h, real races; trained road cyclists, 3 h, an ergometer. Reading them together is the authors' argument, and they say more study is needed.
Part A: no power, wind or temperature data; a final may be raced tactically; finalists are selected on a fast qualifying time, so some regression to the mean is expected (our inference); the analysis uses qualifying position, not the individual rider, as its factor.
Part B: no arm without the first effort; time of day shifts between efforts; the first effort was partly paced, so it may have been less than maximal for most of its length.
n = 12, men only, randomisation not stated, cold water cannot be blinded.
A single double, with nothing on repeating it over days or on adaptation.
How this entry was checked and changed
Why this level

a crossover under 15 (rubric), with an observational elite comparison beside it. Read from the full text (CC BY). The controlled contrast is cold water; the before-and-after comparison of first and second effort has no control