Lactate step test, Demo athlete

A cycling step test of 7 stages, up to 191 W.

LT1, Bsln + 0.5

83 W

1.2 W/kg · 43% of peak

1.4 mmol/L · 140 bpm · RPE 9

5 first-rise methods: 77 to 111 W

LT2, Log-Poly-ModD_max

149 W

2.1 W/kg · 78% of peak

4.2 mmol/L · 182 bpm · RPE 14

8 second-rise methods: 118 to 160 W

Peak

191 W

2.7 W/kg

8.6 mmol/L · HR_max 198 bpm

The lactate curve with the zones in the colors of their domain: green moderate, yellow heavy, red severe. Below, the heart rate of the stages, read at LT1 and LT2.

Five training zones from these two thresholds

Domain			Intensity (W)	Heart rate (bpm)	RPE	Lactate (mmol/L)
Moderate	Zone 1	below LT1	< 62	< 124	< 8	< 1.1
	Zone 2		62–83	124–140	8–9	1.1–1.4
Heavy	Zone 3	LT1 to LT2	83–149	140–182	9–14	1.4–4.2
Severe	Zone 4	above LT2	149–170	182–191	14–16	4.2–6.1
	Zone 5		> 170	> 191	> 16	> 6.1

Predicted performance

What the threshold predicts for a race, from the equations of Heuberger et al. 2018 (refitted).

Race	From the threshold	Expected average power	95 of 100 athletes
45-min time trial	LT2, Log-Poly-ModD_max at 149 W	172 W †	138 to 206 W
† The threshold lies outside the range of the athletes the equation was built on: an extrapolation, to read with care.

How to read it: athletes with an LT2 like this one averaged 172 W in a 45-min time trial; 95 of 100 of them averaged between 138 and 206 W.

What to double-check

9 of 10 checks of the data passed.

Stages

7 stages: the LTP fit has 6 parameters, so 1 degree of freedom is left and LTP can move a lot with one stage (at least 8 stages are better); the fitted curves rest on few points too.

The test

Cycle ergometer, 3-min stages of +25 W from 50 W, earlobe capillary blood (demo_data; RPE simulated)

Stage	Intensity (W)	Lactate (mmol/L)	Heart rate (bpm)	RPE (6‑20)
Rest	0	0.93	96	6
1	50	0.98	114	7
2	75	1.23	134	8
3	100	1.88	154	11
4	125	2.80	170	12
5	150	4.21	182	14
6	175	6.66	193	17
7	191	8.64	198	19

Every method, for the record

	Method	Intensity (W)	Lactate (mmol/L)	Heart rate (bpm)	RPE (6‑20)
Log-log		101	1.8	154	11.0
OBLA	OBLA 2.0	106	2.0	158	11.2
	OBLA 2.5	119	2.5	166	11.8
	OBLA 3.0	130	3.0	172	12.4
	OBLA 3.5	139	3.5	177	13.1
	OBLA 4.0	146	4.0	180	13.7
Bsln+	Bsln + 0.5	83	1.4	140	8.9
	Bsln + 1.0	103	1.9	156	11.1
	Bsln + 1.5	118	2.4	165	11.7
D_max		132	3.1	173	12.5
	ModD_max	140	3.6	177	13.2
	Exp-D_max	135	3.3	175	12.8
	Log-Poly-ModD_max	149	4.2	182	13.9
	Log-Exp-ModD_max	152	4.4	183	14.2
LTP	LTP1	111	2.0	161	11.4
	LTP2	160	4.7	186	15.1
LT_ratio		77	1.3	136	8.3
IAT		125	2.8	170	12.0