Muscle fiber cross sectional area.

<p>Individual values (dotted lines) and mean values (solid lines) before (Pre) and after (Post) the intervention period for athletes adding strength training to their normal endurance training (<i>E+S</i>, left panel) and athletes performing normal endurance training only (<i>E</i>, right panel). Muscle fiber cross sectional area (CSA) for both type I muscle fibers and type II muscle fibers * Different from pre (p ˂ 0.05)</p

Stiffness, Young’s modulus and mean cross section area (CSA) of the patellar tendon.

<p>Stiffness, Young’s modulus and mean cross section area (CSA) of the patellar tendon.</p

Determinants of running performance and running performance.

<p>Individual values (dotted lines) and mean values (solid lines) before (Pre) and after (Post) the intervention period for athletes adding strength training to their normal endurance training (<i>E+S</i>) and athletes performing normal endurance training only (<i>E</i>). a: Body mass adjusted oxygen consumption at 10 km·h^-1. b: Running velocity at 3.5 mmol∙L^-1 [la^-] calculated during the blood lactate profile test. c: The fractional utilization of VO_2max during the 40 min all-out test. d: Running distance during the 40 min all-out test. * Different from pre (p ˂ 0.05).</p

Capillarization.

<p>Individual values (open symbols) and mean values (solid squares) for athletes adding strength training to their normal endurance training (<i>E+S</i>) and athletes performing normal endurance training only (<i>E</i>). a: Percent change in capillaries around each muscle fiber (CAF) for both muscle fiber type I and muscle fiber type II for <i>E+S</i> and <i>E</i>. b: Percent change in capillaries related to fiber area (CAFA) for both muscle fiber type I and muscle fiber type II for <i>E+S</i> and <i>E</i>.</p

Training loads used during the strength training intervention

<p>Training loads used during the strength training intervention</p

Data from the maximal oxygen consumption test.

<p>Data from the maximal oxygen consumption test.</p

Subject characteristics.

<p>Mean ± SD.</p><p>Subject characteristics.</p

Changes in gene expression.

<p>Relative changes in gene expression of irisin-related genes following singular sessions of intense endurance exercise (END) or heavy strength training (STR). Muscle biopsies were sampled 4h post exercise. Data are mean values ± SEM. * = p≤0.05.</p

Plasma concentration of irisin.

<p>Plasma concentration of irisin measured following singular sessions of intense endurance (END) or heavy strength training (STR), or on a control day (CON) without training. Data are mean values ± SEM. The type of intervention had a significant effect on plasma irisin levels (p = 0.022; based on analyses of values from pre, 2h and 6h). There was also an effect of time after exercise (p = 0.007).</p

Lean body mass and exercise induced changes in irisin.

<p>Correlations between proportions of lean body mass and relative changes in plasma irisin following singular sessions of intense endurance exercise (END) or heavy strength training (STR), or on a control day (CON) without training. The X axis represent individual % lean body mass. The Y axis represent individual changes in irisin concentration from baseline to each of the different time points with blood samples. Correlation analyses were performed using Pearson’s method, except of the ones marked ^sp, which were performed using Spearman’s method due to a lack of normal distribution. # = p≤0.05.</p