Table 2.

Energy balance calculation

	CON-LI	OCC	CON-HI
Energy turnover - observed enthalpy output
Heat accumulation in quadriceps muscle (kj)	3.1 ± 0.3	2.7 ± 0.4	4.6 ± 0.7
Heat accumulation in hamstrings (kj)	1.9 ± 0.3	1.4 ± 0.3	2.6 ± 1.0
Heat release to the blood (kj)	1.5 ± 0.3	—	5.2 ± 0.6
Additional heat transfer (kj)	0.3	0.2	0.7
Total observed heat production (kj)	6.8 ± 0.7	4.3 ± 0.5	13.1 ± 2.6
External power output (kj)	2.6 ± 0.1	2.7 ± 0.1	5.8 ± 0.5
Internal power output (kj)	1.5	1.5	1.5
Total (kj)	10.9 ± 0.7	8.5 ± 0.5	20.3 ± 2.9
Energy turnover - observed chemical processes
Aerobic energy production in the thigh (kj)	8.7 ± 0.7	0.7 ± 0.1	15.8 ± 0.8
CP breakdown in quadriceps muscle (kj)	0.4 ± 0.1	1.3 ± 0.2	1.5 ± 0.2
Lactate accumulation in quadriceps muscle (kj)	0.4 ± 0.2	2.6 ± 0.4	3.5 ± 1.1
Lactate release in quadriceps muscle (kj)	0.3 ± 0.1	—	1.3 ± 0.2
Net ATP breakdown and others in quadriceps muscle (kj)	0.2	0.7	0.7
Anaerobic energy output in hamstrings (kj)*	—	2.4 ± 0.4	—
Total (kj)	10.1 ± 0.8	7.8 ± 0.9	22.8 ± 2.3
Ratio between chemical and thermal energy turnover	0.93	0.92	1.12

Observed energy turnover (calculated as the sum of heat accumulation in active muscles and inactive muscles, heat release to the blood, heat transfer to other inactive tissue, external power output and internal power output; see Methods) and energy turnover in observed chemical processes (calculated as the sum of aerobic energy production and CP breakdown, lactate production as well as net ATP utilization and others, see Methods) during 90 s of low intensity knee-extensor exercise with (OCC) and without thigh occlusion (CON-LI) as well as 90 s of high intensity exercise preceded by low intensity exercise (CON-HI). Enthalpy values of 55 and 67 kj (mol ATP synthesized)⁻¹ were used for CP breakdown and lactate production, respectively. An anaerobic energy component from active hamstring involvement has been added in OCC

^*estimated from the ratio between heat accumulation in quadriceps and hamstrings. In CON-LI and CON-HI no such value was added, since the majority of heat accumulation in hamstrings was caused by heat transfer from the blood. In addition, an energy component from active hamstrings involvement, if any, is accounted for by determination of oxygen uptake from the whole thigh. A value of 20.7 and 21.2 kj (1 O₂)⁻¹ was used to convert oxygen utilization to aerobic energy turnover in CON-LI and CON-HI, respectively, assuming a V̇co₂/V̇o₂ ratio of 0.9 and 1.0, respectively. Means ±s.e.m. are given.