Table 1.
Experiment 1 participant characteristics (N = 6), mean (SD) unless otherwise indicated.
Table 2.
Quantitative RT-PCR primer sequences.
Figure 1.
Effects of acute exercise on fibre-type specific glycogen depletion and phosphorylation of AMPKα.
A: Representative slides of immunofluorescent fibre-type analysis (blue fibres are type I, green are type IIA, red/green are type IIAX/IIX) with serial sections of glycogen (periodic acid-Schiff staining) and p-AMPKα Thr172 content before (Rest) and immediately after (Ex) an acute bout of END or LV-HIT. B–C: Fold change in glycogen content from Rest and Ex in type I and IIA fibres. D–E: Fold change in p-AMPKα content from Rest and Ex in type I and IIA fibres. Bars represent 100 µm. AU, arbitrary units; µm, micrometre. *Significant (p<0.05) main effect of exercise.
Figure 2.
Effects of an acute bout of endurance (END) and low-volume high-intensity interval training (LV-HIT) on whole-muscle signaling.
A–D: Fold change in p-AMPKα Thr172 (A), p-ACC Ser79 (B) and p38 MAPK Thr180/Tyr182 (C) content from Rest and Ex. D: Representative western blots, including loading control are also shown. AU, arbitrary units. *Significant (p<0.05) main effect of exercise.
Figure 3.
Effects of training (LV-HIT) on aerobic exercise performance, fibre-type distribution and fibre specific oxidative capacity.
Relative VO2peak (A) and time to 500 kcal (B) at Pre, Mid, and Post for both END and LV-HIT groups are shown. C: Representative slides of immunofluorescent fibre-type analysis (blue fibres are type I, green are type IIA, red/green are type IIAX/IIX) with serial sections of succinate dehydrogenase (SDH) activity Pre and Post END or LV-HIT. D: Percentage of total fibre distribution of type I, IIA and IIAX/IIX fibres Pre and Post END or LV-HIT. E: Fibre-type specific fold change in SDH activity post-training compared to pre-training in type I, IIA and IIAX/IIX fibres. F: Absolute change in estimated oxidative capacity. Bars represent 100 µm. AU, arbitrary units; µm, micrometre. *Significant (p<0.05) main effect of exercise.
Table 3.
Experiment 2 participant characteristics (N = 19) for low volume high-intensity interval (LV-HIT) training (n = 10) and endurance (END) training (n = 9) at baseline (pre), mid-training (mid) and following 6 weeks of training (post); mean (SD) unless otherwise indicated.
Figure 4.
Effects of 6 weeks of endurance (END) and low-volume high-intensity interval training (LV-HIT) on cardiovascular capacity and capillary density.
A: Representative slides of capillarisation Pre and Post training. B: Absolute change in capillary density (capillaries/mm2). C: Change in O2 pulse (mL O2/beat). Bars represent 100 µm. mL, milliliter; mm, millimeter; O2, oxygen; µm, micrometre. *Significant (p<0.05) main effect of exercise.
Figure 5.
Effects of endurance (END) and low-volume high-intensity interval training (LV-HIT) on anaerobic exercise performance and glycolytic capacity.
A: Representative slides of α-glycerophosphate dehydrogenase (GPD) activity Pre and Post training (see Fig. 3C for corresponding fibre-type slides). B: Total work performed during all 4 Wingate bouts. C: Fibre-type specific fold change in GPD activity post-training compared to pre-training in type I, IIA and IIAX/IIX fibres. D: Absolute change in estimated glycolytic capacity. Bars represent 100 µm. AU, arbitrary units; µm, micrometre. †Significant (p<0.05) group by time interaction, *Significant (p<0.05) main effect of exercise, Significant (p<0.05) within group difference (derived from paired t-test).
Figure 6.
Effects of endurance (END) and low-volume high-intensity interval training (LV-HIT) on intramuscular glycogen and triglyceride storage.
A: Representative slides of glycogen (periodic acid-Schiff reaction) and intramuscular triglyceride (IMTG) content (Oil red O staining) Pre and Post training (see Fig. 3C for corresponding fibre-type slides for IMTG stain only). B. Fibre-type specific fold changes in glycogen content in type I, IIA and IIAX/IIX fibres. C. Fibre-type specific fold changes in IMTG content in type I, IIA and IIAX/IIX fibres. Bars represent 100 µm. AU, arbitrary units; µm, micrometre. *Significant (p<0.05) main effect of exercise.