. 2016 Mar 4;594(8):2339–2358. doi: 10.1113/JP271712

Table 2.

Whole‐body and single‐leg data after immobilization for 2 weeks and during 45 min acute isolated knee‐extensor exercise at moderate intensity in young and older men

Whole body	Young men	Older men
Workload (W)	20 ± 1	20 ± 1
Heart rate during exercise (beats min⁻¹)	113 ± 4*	95 ± 5
Percentage of maximal heart rate (%)	59 ± 2	61 ± 4
ss ${\dot{V}}_{O_{2}}$ (ml min⁻¹) (20–30 min)	1066 ± 38(*)	874 ± 35
ss ${\dot{V}}_{{CO}_{2}}$ (ml min⁻¹) (20–30 min)	931 ± 35(*)	738 ± 35
Respiratory exchange ratio	0.87 ± 0.01	0.86 ± 0.01

Isolated leg	Control leg	Immobilized leg	Control leg	Immobilized leg
Leg lean mass§ (kg)	10.7 ± 0.3†	10.1 ± 0.3*	9.3 ± 0.3	9.2 ± 0.3
Watt_max § (W)	42 ± 3†	37 ± 3	45 ± 3†	40 ± 3
Relative workload (% of Watt_max)	50 ± 2†	57 ± 3	47 ± 4†	52 ± 3
ss ${\dot{V}}_{O_{2}}$ (ml min⁻¹) (30–45 min)	212 ± 9	220 ± 12*	148 ± 10	154 ± 14
IMTG at rest§ [μmol (g dry wt)⁻¹]	68 ± 9†	92 ± 11*	114 ± 13†	174 ± 39
ΔIMTG [μmol (g dry wt)⁻¹ (45 min)⁻¹]	−20 ± 17	−20 ± 13	−18 ± 18	−18 ± 21
Glycogen at rest§ [μmol (g dry wt)⁻¹]	221 ± 24	214 ± 23*	257 ± 27	265 ± 37
ΔGlycogen [μmol (g dry wt)⁻¹ (45 min)⁻¹]	36 ± 11	12 ± 23*, ‡	41 ± 13	0 ± 16
HAD activity§ [μmol min⁻¹ (g dry wt)⁻¹]	102 ± 4†	87 ± 5	101 ± 7†	88 ± 5
Reported perceived exertion (1–10)	4.3 ± 0.4†	4.9 ± 0.4	4.2 ± 0.4†	4.3 ± 0.4

Data are mean values ± SEM. *P < 0.05 and (*)0.1 > P < 0.05 young vs. older men (main effect); ^† P < 0.05 control leg vs. immobilized leg of same age group (main effect). Abbreviations: IMTG, intramuscular triglyceride; ss, steady‐state oxygen uptake ( ${\dot{V}}_{O_{2}}$ ) or carbon dioxide output ( ${\dot{V}}_{{CO}_{2}}$ ) during exercise, i.e. the average of 30–45 min; Watt_max, maximal work capacity. The values for ΔIMTG and Δglycogen are the changes over 45 min (pre to post); thus, the positive value of glycogen is utilization (^‡ P < 0.05, pre vs. post, main effect) and the negative value of IMTG is accumulation (n.s.). ^§Previously published data (Reihmane et al. 2013; Gram et al. 2014; Nørregaard et al. 2015; Vigelsø et al. 2015 b).