Table 1.

Metabolic rate and glycogen use during local contractile activity with SPU contractions

Experiment I	Sedentary control	SPU contractions	p-value
Energy expenditure during SPU contractions
METs	0.92 ± 0.04	2.03 ± 0.08	8 × 10−8
AEE (Δ kcal/min during contractions)	—	1.51 ± 0.15	4 × 10−6
% increase whole-body energy expenditure during muscle contractions	—	124 ± 9	3 × 10−7
Muscle glycogen concentration (mmol/kg)
Vastus lateralis at the final biopsy	96 ± 6	92 ± 6	0.601
Soleus at the first biopsy (130 min contractions)	91 ± 5	76 ± 5	0.183
Soleus at the final biopsy (270 min contractions)	90 ± 5	68 ± 5	0.007
% of AEE contributed by soleus glycogen	—	4.1 ± 1.0	0.003

Mean ± SEM. Glycogen contribution to activity energy expenditure (AEE) was based on 3.75 kcal per gram of monomeric glucose units derived from glycogen if completely oxidized. The soleus mass averaged 1.07 ± 0.25 kg (combined mass in both legs) in these 10 participants. The calculation of the % of the total AEE contributed by soleus glycogen during 270 min of contractions was calculated as described in the STAR Methods. The full aerobic combustion of 22 mmol/kg (90–68 mmol/kg) of glycogen would provide about 16 kcal for the combined 1.07 kg soleus muscles. To determine if the energetics of SPU contractions were different than when sitting inactive (control), the results were analyzed with paired t tests. To determine the effect of SPU contractions on soleus glycogen, a mixed effects model with Tukey’s multiple comparison tests was used, because comparisons of control versus contractions were performed at two time points (130 and 270 min). See also Experiment I results in Figures S1 and S8 and Table S2.