Table 1.
Subject characteristics.
Fig 1.
Swimming protocols differ in blood lactate production and perceived exertion but not in heart rate.
Swimming performance, in terms of percentage of maximal speed, decreased in response to SIT (squares) after the sixth bout, while it remained stable during the HIHVT protocol (triangles) (A). Rate of perceived exertion was higher for SIT compared to HIHVT after every bout (B). No significant differences were found in heart rate (C). Blood lactate was higher after SIT at each of the time points examined (D). Results are shown as mean ± SEM. † p < 0.05 significantly different from the first swimming bout. ‡ p < 0.05, ‡‡‡ p < 0.001 significantly different from HIHVT.
Fig 2.
Lipid peroxidation and muscle damage.
Circulating hydroperoxides were unchanged in response to both HIHVT and SIT (A). Lactate dehydrogenase was higher after SIT both at post and at 3 h (B). Creatine kinase was higher after SIT at post (C). Results are shown as mean ± SEM. ‡‡ p < 0.01, ‡‡‡ p < 0.001 vs. HIHVT.
Fig 3.
Molecular signaling in response to swimming.
The ratio of AMPK phosphorylation at Thr172/total AMPK increased at post in response to SIT and at 3h in response to HIHVT (A). The PGC-1α mRNA levels increased at post in response to SIT and at 3 h in response to both SIT and HIHVT (B). Content of PGC-1α protein increased in response to HIHVT at 3 h (C). SIRT1 remains unchanged throughout all the time points examined (D). Results are shown as mean ± SEM. The graph shows a representative crop blot. * p < 0.05 ** p < 0.01 *** p < 0.001 vs. pre. ‡ p < 0.05 vs. SIT.
Fig 4.
The SIRT3 mRNA levels were unchanged at all the time points and swimming intensities examined (A). SOD2 mRNA levels decreased at post in response to HIHVT (B). Results are shown as mean ± SEM. * p < 0.05 vs. pre.
Fig 5.
PGC-1α downstream transcripts.
HIHVT induced a greater transcription of VEGF than SIT after 3 h (A). HIHVT tended to increase COX-I after 3 h (B). NRF1 (C) and TFAM (D) decreased post HIHVT. Results are shown as mean ± SEM. * p < 0.05 vs. pre. ‡ p < 0.05 vs. SIT.