A comparison between laddermill and treadmill maximal oxygen consumption

Maximal O2 consumption (V˙O2max) is an index of the capacity for work over an 8 h workshift. Running on a treadmill is the most common method of eliciting it, because it is an easy, natural exercise, and also, by engaging large muscle masses, larger values are obtained than by other exercises. It has been claimed, however, that climbing a laddermill elicits a still higher V˙O2max, probably because more muscle mass is apparently engaged (legs + arms) than on the treadmill (legs only). However, no data in support of this claim have been presented. To see if differences exist, we conducted progressive tests to exhaustion on 44 active coal miners, on a laddermill (slant angle 75°, vertical separation of rungs 25 cm) and on a treadmill set at a 5% gradient. The subjects' mean (range) age was 37.4 (31–47) years, height 174.3 (164–187) cm, body mass 82.2 (64–103) kg. Mean (range) V˙O2max on the laddermill was 2.83 (2.31–3.64) l · min−1 and 2.98 (2.03–4.22) l · min−1 on the treadmill (P < 0.01, Student's paired t-test). Mean (range) of maximal heart rate fcmax (beats · min−1) on the laddermill and on the treadmill were 181.0 (161–194) and 181.3 (162–195), respectively (NS). Laddermill:treadmill V˙O2max was negatively related to both treadmill V˙O2max · kg body mass−1 (r = −0.410, P < 0.01) and body mass (r = −0.409, P< 0.01). Laddermill:treadmill fcmax was negatively related to treadmill V˙O2max · kg body mass−1 (r = −0.367, P < 0.02) but not to body mass (r = −0.166, P = 0.28). Our data would suggest that for fitter subjects (V˙O2max > 2.6 l · min or V˙O2max · kg body mass−1 > 30 ml · min−1 · kg−1) and/or higher body masses (>70 kg), exercise on the laddermill is not dynamic enough to elicit a V˙O2max as high as on the treadmill. For such subjects, treadmill V˙O2max would overestimate exercise capacity for jobs requiring a fair amount of climbing ladders or ladder-like structures.