The results of the present study suggest the potential of resting HRV to prescribe endurance training by individualizing the timing of vigorous training sessions.

The primary aim of the present study was to investigate the acute gene expression responses of PGC-1 isoforms and PGC-1α target genes related to mitochondrial biogenesis (cytochrome C), angiogenesis (VEGF-A), and muscle hypertrophy (myostatin), after a resistance or endurance exercise bout. In addition, the study aimed to elucidate whether the expression changes of studied transcripts were linked to phosphorylation of AMPK and MAPK p38. Nineteen physically active men were divided into resistance exercise (RE, n = 11) and endurance exercise (EE, n = 8) groups. RE group performed leg press exercise (10 × 10 RM, 50 min) and EE walked on a treadmill (∼80% HRmax, 50 min). Muscle biopsies were obtained from the vastus lateralis muscle before, 30 min, and 180 min after exercise. EE and RE significantly increased the gene expression of alternative promoter originated PGC-1α exon 1b- and 1bxs’-derived isoforms, whereas the proximal promoter originated exon 1a-derived transcripts were less inducible and were upregulated only after EE. Truncated PGC-1α transcripts were upregulated both after EE and RE. Neither RE nor EE affected the expression of PGC-1β. EE upregulated the expression of cytochrome C and VEGF-A, whereas RE upregulated VEGF-A and downregulated myostatin. Both EE and RE increased the levels of p-AMPK and p-MAPK p38, but these changes were not linked to the gene expression responses of PGC-1 isoforms. The present study comprehensively assayed PGC-1 transcripts in human skeletal muscle and showed exercise mode-specific responses thus improving the understanding of early signaling events in exercise-induced muscle adaptations.

The current SRT showed great potential as a practical tool for regular monitoring of individual adaptation to endurance training without time-consuming and expensive laboratory tests.

The aim of this study was to investigate factors that can predict individual adaptation to high-volume or high-intensity endurance training. After the first 8-week preparation period, 37 recreational endurance runners were matched into the high-volume training group (HVT) and high-intensity training group (HIT). During the next 8-week training period, HVT increased their running training volume and HIT increased training intensity. Endurance performance characteristics, heart rate variability (HRV), and serum hormone concentrations were measured before and after the training periods. While HIT improved peak treadmill running speed (RSpeak ) 3.1 ± 2.8% (P < 0.001), no significant changes occurred in HVT (RSpeak : 0.5 ± 1.9%). However, large individual variation was found in the changes of RSpeak in both groups (HVT: -2.8 to 4.1%; HIT: 0-10.2%). A negative relationship was observed between baseline high-frequency power of HRV (HFPnight ) and the individual changes of RSpeak (r = -0.74, P = 0.006) in HVT and a positive relationship (r = 0.63, P = 0.039) in HIT. Individuals with lower HFP showed greater change of RSpeak in HVT, while individuals with higher HFP responded well in HIT. It is concluded that nocturnal HRV can be used to individualize endurance training in recreational runners.

The aim of this study was to investigate whether a submaximal running test (SRT) with post-3 exercise heart rate recovery, heart rate variability and countermovement jump measurements 4 could be used to monitor endurance training adaptation. Thirty-five endurance trained men 5 and women completed an 18-week endurance training program. Maximal endurance 6 performance and maximal oxygen uptake were measured every eight weeks. In addition, SRT 7 with post-exercise heart rate recovery, heart rate variability and countermovement jump 8 measurements were performed every four weeks. SRT consisted of two 6-minute stages at 9 70% and 80% of HR max and a 3-minute stage at 90% HR max , followed by a 2-minute recovery 10 stage for measuring post-exercise heart rate recovery, heart rate variability and 11 countermovement jump test. The highest responders according to the change of maximal 12 endurance performance showed significant improvement in running speeds during stages 2 13 and 3 in SRT, while no changes were observed in the lowest responders. The strongest 14 correlation was found between the change of maximal endurance performance and running 15 speed during stage 3, while no significant relationships were found between the change of 16 maximal endurance performance and the changes of post exercise heart rate recovery, heart 17 rate variability and countermovement jump. Running speed at 90% HR max intensity was the 18 most sensitive variable to monitor adaptation to endurance training. The present submaximal 19 test showed potential to monitor endurance training adaptation. Furthermore, it may serve a 20 practical tool for athletes and coaches to evaluate weekly the effectiveness of training 21 program without interfering normal training habits. 22 23

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