Table 2.

Cardiorespiratory exercise test: characteristics of MZ twin pairs discordant and concordant for obesity

	Discordant Pairs		Concordant Pairs
	Heavier	Leaner	Heavier	Leaner
No. of subjects	14	14	10	10
Wmax, W	197±41	215±63	226±65	234±56
Wmax/LBM, W/kg LBM	3.9±0.5	4.4±0.6†	4.2±0.8	4.4±0.7
V̇o2max, l/min	2.60±0.59	2.67±0.70	2.81±0.81	2.88±0.62
V̇o2max/BW, ml·kg BW–1·min–1	29.2±4.7	36.0±7.4‡	35.9±12.5	38.2±10.8
V̇o2max/LBM, ml·kg LBM–1·min–1	50.8±6.2	54.2±6.1*	52.1±9.0	53.8±6.9
Mechanical efficiency, %	22.0±1.4	23.1±1.3*	23.2±1.1	23.3±1.4
RQ	1.1±0.04	1.1±0.1	1.2±0.1	1.1±0.03
AT, l/min	1.3±0.5	1.5±0.5	1.3±0.3	1.3±0.3
AT/LBM, ml·kg LBM–1·min–1	25.3±7.2	30.2±6.0*	25.0±5.1	25.8±6.7
Resting heart rate, min−1	78±9	75±11	75±12	71±13
Maximal heart rate, min−1	187±7	187±10	187±9	185±7
Resting systolic BP, mmHg	133±15	126±15*	120±7	123±11
Resting diastolic BP, mmHg	71±12	68±8	64±4	65±10
Maximal systolic BP, mmHg	193±30	190±24	191±21	187±18

Data shown as mean ± SD. V̇o_2max, maximal O₂ uptake, W_max, maximal working capacity; BW, total body weight; RQ, respiratory quotient (V̇co_2max/V̇o_2max); AT, anaerobic threshold; BP, blood pressure.

^*P < 0.05,

^†P < 0.01,

^‡P < 0.001 (Student's paired t-test).