Table 2.
Workload, lactate infusion rate, cardiorespiratory parameters and metabolic concentrations
| Variable | Rest | Rest-LC | 65% | 55% | 55%-LC |
|---|---|---|---|---|---|
| Workload (W) | — | — | 181 ± 7 | 151 ± 6† | 151 ± 6† |
| Lactate infusion rate (mg kg−1 min−1) | — | −2.98 ± 0.13 | — | — | 2.76 ± 0.22 |
| V̇O2(l min−1) | 0.27 ± 0.01 | 0.30 ± 0.01‡ | 2.72 ± 0.09* | 2.32 ± 0.07*† | 2.34 ± 0.06*† |
| V̇CO2 (l min−1) | 0.24 ± 0.01 | 0.23 ± 0.01 | 2.47 ± 0.08* | 2.07 ± 0.06*† | 2.01 ± 0.05*† |
| RER | 0.85 ± 0.01 | 0.75 ± 0.01‡ | 0.91 ± 0.01* | 0.89 ± 0.01* | 0.86 ± 0.01*†‡ |
| VE (l min−1) | 7.40 ± 0.40 | 7.40 ± 0.40 | 60.30 ± 1.70* | 48.80 ± 1.40*† | 45.30 ± 1.50*† |
| H13CO3− recovery (%) | 069.8 ± 1.8 | 66.7 ± 2.50 | — | −77.2 ± 1.2 | −82.4 ± 0.9 |
| HR (beats min−1) | 59.0 ± 3.0 | 67.0 ± 3.0‡ | 159.0 ± 4.0* | 143.0 ± 3.0*† | 142.0 ± 2.0*† |
| MAP (mmHg) | 89.6 ± 1.2 | 88.0 ± 1.3 | 99.2 ± 1.1* | 94.0 ± 1.6 | 90.1 ± 1.5 |
| Hct (%) | 45.5 ± 1.0 | 42.5 ± 0.5‡ | 48.0 ± 0.5* | 48.0 ± 0.5* | 43.0 ± 0.5†‡ |
| RPE | — | — | 14.0 ± 1.0 | 12.0 ± 1.0† | 12.0 ± 1.0† |
| Insulin (pg ml−1) | 216.0 ± 47.0 | 168.0 ± 21.0 | 89.5 ± 6.0 | 122.0 ± 12.0 | 141.0 ± 14.0 |
| Glucagon (pg ml−1) | 60.4 ± 4.7 | 46.6 ± 2.2 | 78.9 ± 12.1 | 70.3 ± 7.7 | 57.9 ± 4.2 |
| I/G ratio | 3.8 ± 0.8 | 3.8 ± 0.6 | 1.33 ± 0.2 | 1.99 ± 0.3 | 2.75 ± 0.4 |
Values are means ± s.e.m., n = 6. LC, lactate clamp; W, watts; V̇O2, volume of oxygen consumed per minute; V̇CO2, volume of expired carbon dioxide per minute; RER, respiratory exchange ratio; VE, minute ventilation; HR, heart rate; MAP, mean arterial pressure; Hct, haematocrit; RPE, rating of perceived exertion; I/G ratio, insulin/glucagon ratio.
*
Significantly different from rest (P < 0.05)
†
significantly different from 65 % (P < 0.05)
‡
significally different from corresponding control (non-LC) (P < 0.05).