Low-Volume Speed Endurance Training with Reduced Volume Improves Short-Term Exercise Performance in Highly Trained...

We investigated the effects of low- and high-volume speed endurance training (SET), with a reduced training volume, on sprint ability, short- and long-term exercise capacity, muscle mitochondrial properties, ion transport proteins, and maximal enzyme activity in highly trained athletes.

Highly trained male cyclists (maximal oxygen consumption (V̇O 2max ): 68.3 ± 5.0 mL·min -1 ·kg -1 , n = 24) completed 6 wk of either low (SET-L; 6 × 30-s intervals, n = 8) or high (SET-H; 12 × 30-s intervals, n = 8) volume SET twice per week with a 30% reduction in training volume. A control group (CON; n = 8) maintained their training. Exercise performance was evaluated by i) 6-s sprinting, ii) a 4-min time trial, and iii) a 60-min preload at 60% V̇O 2max followed by a 20-min time trial. A biopsy of m. vastus lateralis was collected before and after the training intervention.

In SET-L, 4-min time trial performance was improved ( P < 0.05) by 3.8%, with no change in SET-H and CON. Sprint ability, prolonged endurance exercise capacity, V̇O 2max , muscle mitochondrial respiratory capacity, maximal citrate synthase activity, fiber type-specific mitochondrial proteins (complexes I-V), and phosphofructokinase (PFK) content did not change in any of the groups. In SET-H, maximal activity of muscle PFK and abundance of Na + -K + pump-subunit α 1 , α 2 , β 1 , and phospholemman (FXYD1) were 20%, 50%, 19%, 24%, and 42% higher ( P < 0.05), respectively after compared with before the intervention, with no changes in SET-L or CON.

Low SET volume combined with a reduced aerobic low- and moderate-intensity training volume does improve short-duration intense exercise performance and maintain sprinting ability, V̇O 2max , endurance exercise performance, and muscle oxidative capacity, whereas, high volume of SET seems necessary to upregulate muscle ion transporter content and maximal PFK activity in highly trained cyclists.